Merge tag 'mt76-for-kvalo-2021-01-29' of https://github.com/nbd168/wireless

[linux-2.6-microblaze.git] / drivers / usb / dwc3 / gadget.c

// SPDX-License-Identifier: GPL-2.0
/*
 * gadget.c - DesignWare USB3 DRD Controller Gadget Framework Link
 *
 * Copyright (C) 2010-2011 Texas Instruments Incorporated - https://www.ti.com
 *
 * Authors: Felipe Balbi <balbi@ti.com>,
 *          Sebastian Andrzej Siewior <bigeasy@linutronix.de>
 */

#include <linux/kernel.h>
#include <linux/delay.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/platform_device.h>
#include <linux/pm_runtime.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/list.h>
#include <linux/dma-mapping.h>

#include <linux/usb/ch9.h>
#include <linux/usb/gadget.h>

#include "debug.h"
#include "core.h"
#include "gadget.h"
#include "io.h"

#define DWC3_ALIGN_FRAME(d, n)  (((d)->frame_number + ((d)->interval * (n))) \
                                        & ~((d)->interval - 1))

/**
 * dwc3_gadget_set_test_mode - enables usb2 test modes
 * @dwc: pointer to our context structure
 * @mode: the mode to set (J, K SE0 NAK, Force Enable)
 *
 * Caller should take care of locking. This function will return 0 on
 * success or -EINVAL if wrong Test Selector is passed.
 */
int dwc3_gadget_set_test_mode(struct dwc3 *dwc, int mode)
{
        u32             reg;

        reg = dwc3_readl(dwc->regs, DWC3_DCTL);
        reg &= ~DWC3_DCTL_TSTCTRL_MASK;

        switch (mode) {
        case USB_TEST_J:
        case USB_TEST_K:
        case USB_TEST_SE0_NAK:
        case USB_TEST_PACKET:
        case USB_TEST_FORCE_ENABLE:
                reg |= mode << 1;
                break;
        default:
                return -EINVAL;
        }

        dwc3_gadget_dctl_write_safe(dwc, reg);

        return 0;
}

/**
 * dwc3_gadget_get_link_state - gets current state of usb link
 * @dwc: pointer to our context structure
 *
 * Caller should take care of locking. This function will
 * return the link state on success (>= 0) or -ETIMEDOUT.
 */
int dwc3_gadget_get_link_state(struct dwc3 *dwc)
{
        u32             reg;

        reg = dwc3_readl(dwc->regs, DWC3_DSTS);

        return DWC3_DSTS_USBLNKST(reg);
}

/**
 * dwc3_gadget_set_link_state - sets usb link to a particular state
 * @dwc: pointer to our context structure
 * @state: the state to put link into
 *
 * Caller should take care of locking. This function will
 * return 0 on success or -ETIMEDOUT.
 */
int dwc3_gadget_set_link_state(struct dwc3 *dwc, enum dwc3_link_state state)
{
        int             retries = 10000;
        u32             reg;

        /*
         * Wait until device controller is ready. Only applies to 1.94a and
         * later RTL.
         */
        if (!DWC3_VER_IS_PRIOR(DWC3, 194A)) {
                while (--retries) {
                        reg = dwc3_readl(dwc->regs, DWC3_DSTS);
                        if (reg & DWC3_DSTS_DCNRD)
                                udelay(5);
                        else
                                break;
                }

                if (retries <= 0)
                        return -ETIMEDOUT;
        }

        reg = dwc3_readl(dwc->regs, DWC3_DCTL);
        reg &= ~DWC3_DCTL_ULSTCHNGREQ_MASK;

        /* set no action before sending new link state change */
        dwc3_writel(dwc->regs, DWC3_DCTL, reg);

        /* set requested state */
        reg |= DWC3_DCTL_ULSTCHNGREQ(state);
        dwc3_writel(dwc->regs, DWC3_DCTL, reg);

        /*
         * The following code is racy when called from dwc3_gadget_wakeup,
         * and is not needed, at least on newer versions
         */
        if (!DWC3_VER_IS_PRIOR(DWC3, 194A))
                return 0;

        /* wait for a change in DSTS */
        retries = 10000;
        while (--retries) {
                reg = dwc3_readl(dwc->regs, DWC3_DSTS);

                if (DWC3_DSTS_USBLNKST(reg) == state)
                        return 0;

                udelay(5);
        }

        return -ETIMEDOUT;
}

/**
 * dwc3_ep_inc_trb - increment a trb index.
 * @index: Pointer to the TRB index to increment.
 *
 * The index should never point to the link TRB. After incrementing,
 * if it is point to the link TRB, wrap around to the beginning. The
 * link TRB is always at the last TRB entry.
 */
static void dwc3_ep_inc_trb(u8 *index)
{
        (*index)++;
        if (*index == (DWC3_TRB_NUM - 1))
                *index = 0;
}

/**
 * dwc3_ep_inc_enq - increment endpoint's enqueue pointer
 * @dep: The endpoint whose enqueue pointer we're incrementing
 */
static void dwc3_ep_inc_enq(struct dwc3_ep *dep)
{
        dwc3_ep_inc_trb(&dep->trb_enqueue);
}

/**
 * dwc3_ep_inc_deq - increment endpoint's dequeue pointer
 * @dep: The endpoint whose enqueue pointer we're incrementing
 */
static void dwc3_ep_inc_deq(struct dwc3_ep *dep)
{
        dwc3_ep_inc_trb(&dep->trb_dequeue);
}

static void dwc3_gadget_del_and_unmap_request(struct dwc3_ep *dep,
                struct dwc3_request *req, int status)
{
        struct dwc3                     *dwc = dep->dwc;

        list_del(&req->list);
        req->remaining = 0;
        req->needs_extra_trb = false;

        if (req->request.status == -EINPROGRESS)
                req->request.status = status;

        if (req->trb)
                usb_gadget_unmap_request_by_dev(dwc->sysdev,
                                &req->request, req->direction);

        req->trb = NULL;
        trace_dwc3_gadget_giveback(req);

        if (dep->number > 1)
                pm_runtime_put(dwc->dev);
}

/**
 * dwc3_gadget_giveback - call struct usb_request's ->complete callback
 * @dep: The endpoint to whom the request belongs to
 * @req: The request we're giving back
 * @status: completion code for the request
 *
 * Must be called with controller's lock held and interrupts disabled. This
 * function will unmap @req and call its ->complete() callback to notify upper
 * layers that it has completed.
 */
void dwc3_gadget_giveback(struct dwc3_ep *dep, struct dwc3_request *req,
                int status)
{
        struct dwc3                     *dwc = dep->dwc;

        dwc3_gadget_del_and_unmap_request(dep, req, status);
        req->status = DWC3_REQUEST_STATUS_COMPLETED;

        spin_unlock(&dwc->lock);
        usb_gadget_giveback_request(&dep->endpoint, &req->request);
        spin_lock(&dwc->lock);
}

/**
 * dwc3_send_gadget_generic_command - issue a generic command for the controller
 * @dwc: pointer to the controller context
 * @cmd: the command to be issued
 * @param: command parameter
 *
 * Caller should take care of locking. Issue @cmd with a given @param to @dwc
 * and wait for its completion.
 */
int dwc3_send_gadget_generic_command(struct dwc3 *dwc, unsigned int cmd,
                u32 param)
{
        u32             timeout = 500;
        int             status = 0;
        int             ret = 0;
        u32             reg;

        dwc3_writel(dwc->regs, DWC3_DGCMDPAR, param);
        dwc3_writel(dwc->regs, DWC3_DGCMD, cmd | DWC3_DGCMD_CMDACT);

        do {
                reg = dwc3_readl(dwc->regs, DWC3_DGCMD);
                if (!(reg & DWC3_DGCMD_CMDACT)) {
                        status = DWC3_DGCMD_STATUS(reg);
                        if (status)
                                ret = -EINVAL;
                        break;
                }
        } while (--timeout);

        if (!timeout) {
                ret = -ETIMEDOUT;
                status = -ETIMEDOUT;
        }

        trace_dwc3_gadget_generic_cmd(cmd, param, status);

        return ret;
}

static int __dwc3_gadget_wakeup(struct dwc3 *dwc);

/**
 * dwc3_send_gadget_ep_cmd - issue an endpoint command
 * @dep: the endpoint to which the command is going to be issued
 * @cmd: the command to be issued
 * @params: parameters to the command
 *
 * Caller should handle locking. This function will issue @cmd with given
 * @params to @dep and wait for its completion.
 */
int dwc3_send_gadget_ep_cmd(struct dwc3_ep *dep, unsigned int cmd,
                struct dwc3_gadget_ep_cmd_params *params)
{
        const struct usb_endpoint_descriptor *desc = dep->endpoint.desc;
        struct dwc3             *dwc = dep->dwc;
        u32                     timeout = 5000;
        u32                     saved_config = 0;
        u32                     reg;

        int                     cmd_status = 0;
        int                     ret = -EINVAL;

        /*
         * When operating in USB 2.0 speeds (HS/FS), if GUSB2PHYCFG.ENBLSLPM or
         * GUSB2PHYCFG.SUSPHY is set, it must be cleared before issuing an
         * endpoint command.
         *
         * Save and clear both GUSB2PHYCFG.ENBLSLPM and GUSB2PHYCFG.SUSPHY
         * settings. Restore them after the command is completed.
         *
         * DWC_usb3 3.30a and DWC_usb31 1.90a programming guide section 3.2.2
         */
        if (dwc->gadget->speed <= USB_SPEED_HIGH) {
                reg = dwc3_readl(dwc->regs, DWC3_GUSB2PHYCFG(0));
                if (unlikely(reg & DWC3_GUSB2PHYCFG_SUSPHY)) {
                        saved_config |= DWC3_GUSB2PHYCFG_SUSPHY;
                        reg &= ~DWC3_GUSB2PHYCFG_SUSPHY;
                }

                if (reg & DWC3_GUSB2PHYCFG_ENBLSLPM) {
                        saved_config |= DWC3_GUSB2PHYCFG_ENBLSLPM;
                        reg &= ~DWC3_GUSB2PHYCFG_ENBLSLPM;
                }

                if (saved_config)
                        dwc3_writel(dwc->regs, DWC3_GUSB2PHYCFG(0), reg);
        }

        if (DWC3_DEPCMD_CMD(cmd) == DWC3_DEPCMD_STARTTRANSFER) {
                int             needs_wakeup;

                needs_wakeup = (dwc->link_state == DWC3_LINK_STATE_U1 ||
                                dwc->link_state == DWC3_LINK_STATE_U2 ||
                                dwc->link_state == DWC3_LINK_STATE_U3);

                if (unlikely(needs_wakeup)) {
                        ret = __dwc3_gadget_wakeup(dwc);
                        dev_WARN_ONCE(dwc->dev, ret, "wakeup failed --> %d\n",
                                        ret);
                }
        }

        dwc3_writel(dep->regs, DWC3_DEPCMDPAR0, params->param0);
        dwc3_writel(dep->regs, DWC3_DEPCMDPAR1, params->param1);
        dwc3_writel(dep->regs, DWC3_DEPCMDPAR2, params->param2);

        /*
         * Synopsys Databook 2.60a states in section 6.3.2.5.6 of that if we're
         * not relying on XferNotReady, we can make use of a special "No
         * Response Update Transfer" command where we should clear both CmdAct
         * and CmdIOC bits.
         *
         * With this, we don't need to wait for command completion and can
         * straight away issue further commands to the endpoint.
         *
         * NOTICE: We're making an assumption that control endpoints will never
         * make use of Update Transfer command. This is a safe assumption
         * because we can never have more than one request at a time with
         * Control Endpoints. If anybody changes that assumption, this chunk
         * needs to be updated accordingly.
         */
        if (DWC3_DEPCMD_CMD(cmd) == DWC3_DEPCMD_UPDATETRANSFER &&
                        !usb_endpoint_xfer_isoc(desc))
                cmd &= ~(DWC3_DEPCMD_CMDIOC | DWC3_DEPCMD_CMDACT);
        else
                cmd |= DWC3_DEPCMD_CMDACT;

        dwc3_writel(dep->regs, DWC3_DEPCMD, cmd);
        do {
                reg = dwc3_readl(dep->regs, DWC3_DEPCMD);
                if (!(reg & DWC3_DEPCMD_CMDACT)) {
                        cmd_status = DWC3_DEPCMD_STATUS(reg);

                        switch (cmd_status) {
                        case 0:
                                ret = 0;
                                break;
                        case DEPEVT_TRANSFER_NO_RESOURCE:
                                dev_WARN(dwc->dev, "No resource for %s\n",
                                         dep->name);
                                ret = -EINVAL;
                                break;
                        case DEPEVT_TRANSFER_BUS_EXPIRY:
                                /*
                                 * SW issues START TRANSFER command to
                                 * isochronous ep with future frame interval. If
                                 * future interval time has already passed when
                                 * core receives the command, it will respond
                                 * with an error status of 'Bus Expiry'.
                                 *
                                 * Instead of always returning -EINVAL, let's
                                 * give a hint to the gadget driver that this is
                                 * the case by returning -EAGAIN.
                                 */
                                ret = -EAGAIN;
                                break;
                        default:
                                dev_WARN(dwc->dev, "UNKNOWN cmd status\n");
                        }

                        break;
                }
        } while (--timeout);

        if (timeout == 0) {
                ret = -ETIMEDOUT;
                cmd_status = -ETIMEDOUT;
        }

        trace_dwc3_gadget_ep_cmd(dep, cmd, params, cmd_status);

        if (DWC3_DEPCMD_CMD(cmd) == DWC3_DEPCMD_STARTTRANSFER) {
                if (ret == 0)
                        dep->flags |= DWC3_EP_TRANSFER_STARTED;

                if (ret != -ETIMEDOUT)
                        dwc3_gadget_ep_get_transfer_index(dep);
        }

        if (saved_config) {
                reg = dwc3_readl(dwc->regs, DWC3_GUSB2PHYCFG(0));
                reg |= saved_config;
                dwc3_writel(dwc->regs, DWC3_GUSB2PHYCFG(0), reg);
        }

        return ret;
}

static int dwc3_send_clear_stall_ep_cmd(struct dwc3_ep *dep)
{
        struct dwc3 *dwc = dep->dwc;
        struct dwc3_gadget_ep_cmd_params params;
        u32 cmd = DWC3_DEPCMD_CLEARSTALL;

        /*
         * As of core revision 2.60a the recommended programming model
         * is to set the ClearPendIN bit when issuing a Clear Stall EP
         * command for IN endpoints. This is to prevent an issue where
         * some (non-compliant) hosts may not send ACK TPs for pending
         * IN transfers due to a mishandled error condition. Synopsys
         * STAR 9000614252.
         */
        if (dep->direction &&
            !DWC3_VER_IS_PRIOR(DWC3, 260A) &&
            (dwc->gadget->speed >= USB_SPEED_SUPER))
                cmd |= DWC3_DEPCMD_CLEARPENDIN;

        memset(&params, 0, sizeof(params));

        return dwc3_send_gadget_ep_cmd(dep, cmd, &params);
}

static dma_addr_t dwc3_trb_dma_offset(struct dwc3_ep *dep,
                struct dwc3_trb *trb)
{
        u32             offset = (char *) trb - (char *) dep->trb_pool;

        return dep->trb_pool_dma + offset;
}

static int dwc3_alloc_trb_pool(struct dwc3_ep *dep)
{
        struct dwc3             *dwc = dep->dwc;

        if (dep->trb_pool)
                return 0;

        dep->trb_pool = dma_alloc_coherent(dwc->sysdev,
                        sizeof(struct dwc3_trb) * DWC3_TRB_NUM,
                        &dep->trb_pool_dma, GFP_KERNEL);
        if (!dep->trb_pool) {
                dev_err(dep->dwc->dev, "failed to allocate trb pool for %s\n",
                                dep->name);
                return -ENOMEM;
        }

        return 0;
}

static void dwc3_free_trb_pool(struct dwc3_ep *dep)
{
        struct dwc3             *dwc = dep->dwc;

        dma_free_coherent(dwc->sysdev, sizeof(struct dwc3_trb) * DWC3_TRB_NUM,
                        dep->trb_pool, dep->trb_pool_dma);

        dep->trb_pool = NULL;
        dep->trb_pool_dma = 0;
}

static int dwc3_gadget_set_xfer_resource(struct dwc3_ep *dep)
{
        struct dwc3_gadget_ep_cmd_params params;

        memset(&params, 0x00, sizeof(params));

        params.param0 = DWC3_DEPXFERCFG_NUM_XFER_RES(1);

        return dwc3_send_gadget_ep_cmd(dep, DWC3_DEPCMD_SETTRANSFRESOURCE,
                        &params);
}

/**
 * dwc3_gadget_start_config - configure ep resources
 * @dep: endpoint that is being enabled
 *
 * Issue a %DWC3_DEPCMD_DEPSTARTCFG command to @dep. After the command's
 * completion, it will set Transfer Resource for all available endpoints.
 *
 * The assignment of transfer resources cannot perfectly follow the data book
 * due to the fact that the controller driver does not have all knowledge of the
 * configuration in advance. It is given this information piecemeal by the
 * composite gadget framework after every SET_CONFIGURATION and
 * SET_INTERFACE. Trying to follow the databook programming model in this
 * scenario can cause errors. For two reasons:
 *
 * 1) The databook says to do %DWC3_DEPCMD_DEPSTARTCFG for every
 * %USB_REQ_SET_CONFIGURATION and %USB_REQ_SET_INTERFACE (8.1.5). This is
 * incorrect in the scenario of multiple interfaces.
 *
 * 2) The databook does not mention doing more %DWC3_DEPCMD_DEPXFERCFG for new
 * endpoint on alt setting (8.1.6).
 *
 * The following simplified method is used instead:
 *
 * All hardware endpoints can be assigned a transfer resource and this setting
 * will stay persistent until either a core reset or hibernation. So whenever we
 * do a %DWC3_DEPCMD_DEPSTARTCFG(0) we can go ahead and do
 * %DWC3_DEPCMD_DEPXFERCFG for every hardware endpoint as well. We are
 * guaranteed that there are as many transfer resources as endpoints.
 *
 * This function is called for each endpoint when it is being enabled but is
 * triggered only when called for EP0-out, which always happens first, and which
 * should only happen in one of the above conditions.
 */
static int dwc3_gadget_start_config(struct dwc3_ep *dep)
{
        struct dwc3_gadget_ep_cmd_params params;
        struct dwc3             *dwc;
        u32                     cmd;
        int                     i;
        int                     ret;

        if (dep->number)
                return 0;

        memset(&params, 0x00, sizeof(params));
        cmd = DWC3_DEPCMD_DEPSTARTCFG;
        dwc = dep->dwc;

        ret = dwc3_send_gadget_ep_cmd(dep, cmd, &params);
        if (ret)
                return ret;

        for (i = 0; i < DWC3_ENDPOINTS_NUM; i++) {
                struct dwc3_ep *dep = dwc->eps[i];

                if (!dep)
                        continue;

                ret = dwc3_gadget_set_xfer_resource(dep);
                if (ret)
                        return ret;
        }

        return 0;
}

static int dwc3_gadget_set_ep_config(struct dwc3_ep *dep, unsigned int action)
{
        const struct usb_ss_ep_comp_descriptor *comp_desc;
        const struct usb_endpoint_descriptor *desc;
        struct dwc3_gadget_ep_cmd_params params;
        struct dwc3 *dwc = dep->dwc;

        comp_desc = dep->endpoint.comp_desc;
        desc = dep->endpoint.desc;

        memset(&params, 0x00, sizeof(params));

        params.param0 = DWC3_DEPCFG_EP_TYPE(usb_endpoint_type(desc))
                | DWC3_DEPCFG_MAX_PACKET_SIZE(usb_endpoint_maxp(desc));

        /* Burst size is only needed in SuperSpeed mode */
        if (dwc->gadget->speed >= USB_SPEED_SUPER) {
                u32 burst = dep->endpoint.maxburst;

                params.param0 |= DWC3_DEPCFG_BURST_SIZE(burst - 1);
        }

        params.param0 |= action;
        if (action == DWC3_DEPCFG_ACTION_RESTORE)
                params.param2 |= dep->saved_state;

        if (usb_endpoint_xfer_control(desc))
                params.param1 = DWC3_DEPCFG_XFER_COMPLETE_EN;

        if (dep->number <= 1 || usb_endpoint_xfer_isoc(desc))
                params.param1 |= DWC3_DEPCFG_XFER_NOT_READY_EN;

        if (usb_ss_max_streams(comp_desc) && usb_endpoint_xfer_bulk(desc)) {
                params.param1 |= DWC3_DEPCFG_STREAM_CAPABLE
                        | DWC3_DEPCFG_XFER_COMPLETE_EN
                        | DWC3_DEPCFG_STREAM_EVENT_EN;
                dep->stream_capable = true;
        }

        if (!usb_endpoint_xfer_control(desc))
                params.param1 |= DWC3_DEPCFG_XFER_IN_PROGRESS_EN;

        /*
         * We are doing 1:1 mapping for endpoints, meaning
         * Physical Endpoints 2 maps to Logical Endpoint 2 and
         * so on. We consider the direction bit as part of the physical
         * endpoint number. So USB endpoint 0x81 is 0x03.
         */
        params.param1 |= DWC3_DEPCFG_EP_NUMBER(dep->number);

        /*
         * We must use the lower 16 TX FIFOs even though
         * HW might have more
         */
        if (dep->direction)
                params.param0 |= DWC3_DEPCFG_FIFO_NUMBER(dep->number >> 1);

        if (desc->bInterval) {
                params.param1 |= DWC3_DEPCFG_BINTERVAL_M1(desc->bInterval - 1);
                dep->interval = 1 << (desc->bInterval - 1);
        }

        return dwc3_send_gadget_ep_cmd(dep, DWC3_DEPCMD_SETEPCONFIG, &params);
}

static void dwc3_stop_active_transfer(struct dwc3_ep *dep, bool force,
                bool interrupt);

/**
 * __dwc3_gadget_ep_enable - initializes a hw endpoint
 * @dep: endpoint to be initialized
 * @action: one of INIT, MODIFY or RESTORE
 *
 * Caller should take care of locking. Execute all necessary commands to
 * initialize a HW endpoint so it can be used by a gadget driver.
 */
static int __dwc3_gadget_ep_enable(struct dwc3_ep *dep, unsigned int action)
{
        const struct usb_endpoint_descriptor *desc = dep->endpoint.desc;
        struct dwc3             *dwc = dep->dwc;

        u32                     reg;
        int                     ret;

        if (!(dep->flags & DWC3_EP_ENABLED)) {
                ret = dwc3_gadget_start_config(dep);
                if (ret)
                        return ret;
        }

        ret = dwc3_gadget_set_ep_config(dep, action);
        if (ret)
                return ret;

        if (!(dep->flags & DWC3_EP_ENABLED)) {
                struct dwc3_trb *trb_st_hw;
                struct dwc3_trb *trb_link;

                dep->type = usb_endpoint_type(desc);
                dep->flags |= DWC3_EP_ENABLED;

                reg = dwc3_readl(dwc->regs, DWC3_DALEPENA);
                reg |= DWC3_DALEPENA_EP(dep->number);
                dwc3_writel(dwc->regs, DWC3_DALEPENA, reg);

                if (usb_endpoint_xfer_control(desc))
                        goto out;

                /* Initialize the TRB ring */
                dep->trb_dequeue = 0;
                dep->trb_enqueue = 0;
                memset(dep->trb_pool, 0,
                       sizeof(struct dwc3_trb) * DWC3_TRB_NUM);

                /* Link TRB. The HWO bit is never reset */
                trb_st_hw = &dep->trb_pool[0];

                trb_link = &dep->trb_pool[DWC3_TRB_NUM - 1];
                trb_link->bpl = lower_32_bits(dwc3_trb_dma_offset(dep, trb_st_hw));
                trb_link->bph = upper_32_bits(dwc3_trb_dma_offset(dep, trb_st_hw));
                trb_link->ctrl |= DWC3_TRBCTL_LINK_TRB;
                trb_link->ctrl |= DWC3_TRB_CTRL_HWO;
        }

        /*
         * Issue StartTransfer here with no-op TRB so we can always rely on No
         * Response Update Transfer command.
         */
        if (usb_endpoint_xfer_bulk(desc) ||
                        usb_endpoint_xfer_int(desc)) {
                struct dwc3_gadget_ep_cmd_params params;
                struct dwc3_trb *trb;
                dma_addr_t trb_dma;
                u32 cmd;

                memset(&params, 0, sizeof(params));
                trb = &dep->trb_pool[0];
                trb_dma = dwc3_trb_dma_offset(dep, trb);

                params.param0 = upper_32_bits(trb_dma);
                params.param1 = lower_32_bits(trb_dma);

                cmd = DWC3_DEPCMD_STARTTRANSFER;

                ret = dwc3_send_gadget_ep_cmd(dep, cmd, &params);
                if (ret < 0)
                        return ret;

                if (dep->stream_capable) {
                        /*
                         * For streams, at start, there maybe a race where the
                         * host primes the endpoint before the function driver
                         * queues a request to initiate a stream. In that case,
                         * the controller will not see the prime to generate the
                         * ERDY and start stream. To workaround this, issue a
                         * no-op TRB as normal, but end it immediately. As a
                         * result, when the function driver queues the request,
                         * the next START_TRANSFER command will cause the
                         * controller to generate an ERDY to initiate the
                         * stream.
                         */
                        dwc3_stop_active_transfer(dep, true, true);

                        /*
                         * All stream eps will reinitiate stream on NoStream
                         * rejection until we can determine that the host can
                         * prime after the first transfer.
                         */
                        dep->flags |= DWC3_EP_FORCE_RESTART_STREAM;
                }
        }

out:
        trace_dwc3_gadget_ep_enable(dep);

        return 0;
}

static void dwc3_remove_requests(struct dwc3 *dwc, struct dwc3_ep *dep)
{
        struct dwc3_request             *req;

        dwc3_stop_active_transfer(dep, true, false);

        /* - giveback all requests to gadget driver */
        while (!list_empty(&dep->started_list)) {
                req = next_request(&dep->started_list);

                dwc3_gadget_giveback(dep, req, -ESHUTDOWN);
        }

        while (!list_empty(&dep->pending_list)) {
                req = next_request(&dep->pending_list);

                dwc3_gadget_giveback(dep, req, -ESHUTDOWN);
        }

        while (!list_empty(&dep->cancelled_list)) {
                req = next_request(&dep->cancelled_list);

                dwc3_gadget_giveback(dep, req, -ESHUTDOWN);
        }
}

/**
 * __dwc3_gadget_ep_disable - disables a hw endpoint
 * @dep: the endpoint to disable
 *
 * This function undoes what __dwc3_gadget_ep_enable did and also removes
 * requests which are currently being processed by the hardware and those which
 * are not yet scheduled.
 *
 * Caller should take care of locking.
 */
static int __dwc3_gadget_ep_disable(struct dwc3_ep *dep)
{
        struct dwc3             *dwc = dep->dwc;
        u32                     reg;

        trace_dwc3_gadget_ep_disable(dep);

        dwc3_remove_requests(dwc, dep);

        /* make sure HW endpoint isn't stalled */
        if (dep->flags & DWC3_EP_STALL)
                __dwc3_gadget_ep_set_halt(dep, 0, false);

        reg = dwc3_readl(dwc->regs, DWC3_DALEPENA);
        reg &= ~DWC3_DALEPENA_EP(dep->number);
        dwc3_writel(dwc->regs, DWC3_DALEPENA, reg);

        dep->stream_capable = false;
        dep->type = 0;
        dep->flags = 0;

        /* Clear out the ep descriptors for non-ep0 */
        if (dep->number > 1) {
                dep->endpoint.comp_desc = NULL;
                dep->endpoint.desc = NULL;
        }

        return 0;
}

/* -------------------------------------------------------------------------- */

static int dwc3_gadget_ep0_enable(struct usb_ep *ep,
                const struct usb_endpoint_descriptor *desc)
{
        return -EINVAL;
}

static int dwc3_gadget_ep0_disable(struct usb_ep *ep)
{
        return -EINVAL;
}

/* -------------------------------------------------------------------------- */

static int dwc3_gadget_ep_enable(struct usb_ep *ep,
                const struct usb_endpoint_descriptor *desc)
{
        struct dwc3_ep                  *dep;
        struct dwc3                     *dwc;
        unsigned long                   flags;
        int                             ret;

        if (!ep || !desc || desc->bDescriptorType != USB_DT_ENDPOINT) {
                pr_debug("dwc3: invalid parameters\n");
                return -EINVAL;
        }

        if (!desc->wMaxPacketSize) {
                pr_debug("dwc3: missing wMaxPacketSize\n");
                return -EINVAL;
        }

        dep = to_dwc3_ep(ep);
        dwc = dep->dwc;

        if (dev_WARN_ONCE(dwc->dev, dep->flags & DWC3_EP_ENABLED,
                                        "%s is already enabled\n",
                                        dep->name))
                return 0;

        spin_lock_irqsave(&dwc->lock, flags);
        ret = __dwc3_gadget_ep_enable(dep, DWC3_DEPCFG_ACTION_INIT);
        spin_unlock_irqrestore(&dwc->lock, flags);

        return ret;
}

static int dwc3_gadget_ep_disable(struct usb_ep *ep)
{
        struct dwc3_ep                  *dep;
        struct dwc3                     *dwc;
        unsigned long                   flags;
        int                             ret;

        if (!ep) {
                pr_debug("dwc3: invalid parameters\n");
                return -EINVAL;
        }

        dep = to_dwc3_ep(ep);
        dwc = dep->dwc;

        if (dev_WARN_ONCE(dwc->dev, !(dep->flags & DWC3_EP_ENABLED),
                                        "%s is already disabled\n",
                                        dep->name))
                return 0;

        spin_lock_irqsave(&dwc->lock, flags);
        ret = __dwc3_gadget_ep_disable(dep);
        spin_unlock_irqrestore(&dwc->lock, flags);

        return ret;
}

static struct usb_request *dwc3_gadget_ep_alloc_request(struct usb_ep *ep,
                gfp_t gfp_flags)
{
        struct dwc3_request             *req;
        struct dwc3_ep                  *dep = to_dwc3_ep(ep);

        req = kzalloc(sizeof(*req), gfp_flags);
        if (!req)
                return NULL;

        req->direction  = dep->direction;
        req->epnum      = dep->number;
        req->dep        = dep;
        req->status     = DWC3_REQUEST_STATUS_UNKNOWN;

        trace_dwc3_alloc_request(req);

        return &req->request;
}

static void dwc3_gadget_ep_free_request(struct usb_ep *ep,
                struct usb_request *request)
{
        struct dwc3_request             *req = to_dwc3_request(request);

        trace_dwc3_free_request(req);
        kfree(req);
}

/**
 * dwc3_ep_prev_trb - returns the previous TRB in the ring
 * @dep: The endpoint with the TRB ring
 * @index: The index of the current TRB in the ring
 *
 * Returns the TRB prior to the one pointed to by the index. If the
 * index is 0, we will wrap backwards, skip the link TRB, and return
 * the one just before that.
 */
static struct dwc3_trb *dwc3_ep_prev_trb(struct dwc3_ep *dep, u8 index)
{
        u8 tmp = index;

        if (!tmp)
                tmp = DWC3_TRB_NUM - 1;

        return &dep->trb_pool[tmp - 1];
}

static u32 dwc3_calc_trbs_left(struct dwc3_ep *dep)
{
        struct dwc3_trb         *tmp;
        u8                      trbs_left;

        /*
         * If enqueue & dequeue are equal than it is either full or empty.
         *
         * One way to know for sure is if the TRB right before us has HWO bit
         * set or not. If it has, then we're definitely full and can't fit any
         * more transfers in our ring.
         */
        if (dep->trb_enqueue == dep->trb_dequeue) {
                tmp = dwc3_ep_prev_trb(dep, dep->trb_enqueue);
                if (tmp->ctrl & DWC3_TRB_CTRL_HWO)
                        return 0;

                return DWC3_TRB_NUM - 1;
        }

        trbs_left = dep->trb_dequeue - dep->trb_enqueue;
        trbs_left &= (DWC3_TRB_NUM - 1);

        if (dep->trb_dequeue < dep->trb_enqueue)
                trbs_left--;

        return trbs_left;
}

static void __dwc3_prepare_one_trb(struct dwc3_ep *dep, struct dwc3_trb *trb,
                dma_addr_t dma, unsigned int length, unsigned int chain,
                unsigned int node, unsigned int stream_id,
                unsigned int short_not_ok, unsigned int no_interrupt,
                unsigned int is_last, bool must_interrupt)
{
        struct dwc3             *dwc = dep->dwc;
        struct usb_gadget       *gadget = dwc->gadget;
        enum usb_device_speed   speed = gadget->speed;

        trb->size = DWC3_TRB_SIZE_LENGTH(length);
        trb->bpl = lower_32_bits(dma);
        trb->bph = upper_32_bits(dma);

        switch (usb_endpoint_type(dep->endpoint.desc)) {
        case USB_ENDPOINT_XFER_CONTROL:
                trb->ctrl = DWC3_TRBCTL_CONTROL_SETUP;
                break;

        case USB_ENDPOINT_XFER_ISOC:
                if (!node) {
                        trb->ctrl = DWC3_TRBCTL_ISOCHRONOUS_FIRST;

                        /*
                         * USB Specification 2.0 Section 5.9.2 states that: "If
                         * there is only a single transaction in the microframe,
                         * only a DATA0 data packet PID is used.  If there are
                         * two transactions per microframe, DATA1 is used for
                         * the first transaction data packet and DATA0 is used
                         * for the second transaction data packet.  If there are
                         * three transactions per microframe, DATA2 is used for
                         * the first transaction data packet, DATA1 is used for
                         * the second, and DATA0 is used for the third."
                         *
                         * IOW, we should satisfy the following cases:
                         *
                         * 1) length <= maxpacket
                         *      - DATA0
                         *
                         * 2) maxpacket < length <= (2 * maxpacket)
                         *      - DATA1, DATA0
                         *
                         * 3) (2 * maxpacket) < length <= (3 * maxpacket)
                         *      - DATA2, DATA1, DATA0
                         */
                        if (speed == USB_SPEED_HIGH) {
                                struct usb_ep *ep = &dep->endpoint;
                                unsigned int mult = 2;
                                unsigned int maxp = usb_endpoint_maxp(ep->desc);

                                if (length <= (2 * maxp))
                                        mult--;

                                if (length <= maxp)
                                        mult--;

                                trb->size |= DWC3_TRB_SIZE_PCM1(mult);
                        }
                } else {
                        trb->ctrl = DWC3_TRBCTL_ISOCHRONOUS;
                }

                /* always enable Interrupt on Missed ISOC */
                trb->ctrl |= DWC3_TRB_CTRL_ISP_IMI;
                break;

        case USB_ENDPOINT_XFER_BULK:
        case USB_ENDPOINT_XFER_INT:
                trb->ctrl = DWC3_TRBCTL_NORMAL;
                break;
        default:
                /*
                 * This is only possible with faulty memory because we
                 * checked it already :)
                 */
                dev_WARN(dwc->dev, "Unknown endpoint type %d\n",
                                usb_endpoint_type(dep->endpoint.desc));
        }

        /*
         * Enable Continue on Short Packet
         * when endpoint is not a stream capable
         */
        if (usb_endpoint_dir_out(dep->endpoint.desc)) {
                if (!dep->stream_capable)
                        trb->ctrl |= DWC3_TRB_CTRL_CSP;

                if (short_not_ok)
                        trb->ctrl |= DWC3_TRB_CTRL_ISP_IMI;
        }

        if ((!no_interrupt && !chain) || must_interrupt)
                trb->ctrl |= DWC3_TRB_CTRL_IOC;

        if (chain)
                trb->ctrl |= DWC3_TRB_CTRL_CHN;
        else if (dep->stream_capable && is_last)
                trb->ctrl |= DWC3_TRB_CTRL_LST;

        if (usb_endpoint_xfer_bulk(dep->endpoint.desc) && dep->stream_capable)
                trb->ctrl |= DWC3_TRB_CTRL_SID_SOFN(stream_id);

        trb->ctrl |= DWC3_TRB_CTRL_HWO;

        dwc3_ep_inc_enq(dep);

        trace_dwc3_prepare_trb(dep, trb);
}

/**
 * dwc3_prepare_one_trb - setup one TRB from one request
 * @dep: endpoint for which this request is prepared
 * @req: dwc3_request pointer
 * @trb_length: buffer size of the TRB
 * @chain: should this TRB be chained to the next?
 * @node: only for isochronous endpoints. First TRB needs different type.
 * @use_bounce_buffer: set to use bounce buffer
 * @must_interrupt: set to interrupt on TRB completion
 */
static void dwc3_prepare_one_trb(struct dwc3_ep *dep,
                struct dwc3_request *req, unsigned int trb_length,
                unsigned int chain, unsigned int node, bool use_bounce_buffer,
                bool must_interrupt)
{
        struct dwc3_trb         *trb;
        dma_addr_t              dma;
        unsigned int            stream_id = req->request.stream_id;
        unsigned int            short_not_ok = req->request.short_not_ok;
        unsigned int            no_interrupt = req->request.no_interrupt;
        unsigned int            is_last = req->request.is_last;

        if (use_bounce_buffer)
                dma = dep->dwc->bounce_addr;
        else if (req->request.num_sgs > 0)
                dma = sg_dma_address(req->start_sg);
        else
                dma = req->request.dma;

        trb = &dep->trb_pool[dep->trb_enqueue];

        if (!req->trb) {
                dwc3_gadget_move_started_request(req);
                req->trb = trb;
                req->trb_dma = dwc3_trb_dma_offset(dep, trb);
        }

        req->num_trbs++;

        __dwc3_prepare_one_trb(dep, trb, dma, trb_length, chain, node,
                        stream_id, short_not_ok, no_interrupt, is_last,
                        must_interrupt);
}

static bool dwc3_needs_extra_trb(struct dwc3_ep *dep, struct dwc3_request *req)
{
        unsigned int maxp = usb_endpoint_maxp(dep->endpoint.desc);
        unsigned int rem = req->request.length % maxp;

        if ((req->request.length && req->request.zero && !rem &&
                        !usb_endpoint_xfer_isoc(dep->endpoint.desc)) ||
                        (!req->direction && rem))
                return true;

        return false;
}

/**
 * dwc3_prepare_last_sg - prepare TRBs for the last SG entry
 * @dep: The endpoint that the request belongs to
 * @req: The request to prepare
 * @entry_length: The last SG entry size
 * @node: Indicates whether this is not the first entry (for isoc only)
 *
 * Return the number of TRBs prepared.
 */
static int dwc3_prepare_last_sg(struct dwc3_ep *dep,
                struct dwc3_request *req, unsigned int entry_length,
                unsigned int node)
{
        unsigned int maxp = usb_endpoint_maxp(dep->endpoint.desc);
        unsigned int rem = req->request.length % maxp;
        unsigned int num_trbs = 1;

        if (dwc3_needs_extra_trb(dep, req))
                num_trbs++;

        if (dwc3_calc_trbs_left(dep) < num_trbs)
                return 0;

        req->needs_extra_trb = num_trbs > 1;

        /* Prepare a normal TRB */
        if (req->direction || req->request.length)
                dwc3_prepare_one_trb(dep, req, entry_length,
                                req->needs_extra_trb, node, false, false);

        /* Prepare extra TRBs for ZLP and MPS OUT transfer alignment */
        if ((!req->direction && !req->request.length) || req->needs_extra_trb)
                dwc3_prepare_one_trb(dep, req,
                                req->direction ? 0 : maxp - rem,
                                false, 1, true, false);

        return num_trbs;
}

static int dwc3_prepare_trbs_sg(struct dwc3_ep *dep,
                struct dwc3_request *req)
{
        struct scatterlist *sg = req->start_sg;
        struct scatterlist *s;
        int             i;
        unsigned int length = req->request.length;
        unsigned int remaining = req->request.num_mapped_sgs
                - req->num_queued_sgs;
        unsigned int num_trbs = req->num_trbs;
        bool needs_extra_trb = dwc3_needs_extra_trb(dep, req);

        /*
         * If we resume preparing the request, then get the remaining length of
         * the request and resume where we left off.
         */
        for_each_sg(req->request.sg, s, req->num_queued_sgs, i)
                length -= sg_dma_len(s);

        for_each_sg(sg, s, remaining, i) {
                unsigned int num_trbs_left = dwc3_calc_trbs_left(dep);
                unsigned int trb_length;
                bool must_interrupt = false;
                bool last_sg = false;

                trb_length = min_t(unsigned int, length, sg_dma_len(s));

                length -= trb_length;

                /*
                 * IOMMU driver is coalescing the list of sgs which shares a
                 * page boundary into one and giving it to USB driver. With
                 * this the number of sgs mapped is not equal to the number of
                 * sgs passed. So mark the chain bit to false if it isthe last
                 * mapped sg.
                 */
                if ((i == remaining - 1) || !length)
                        last_sg = true;

                if (!num_trbs_left)
                        break;

                if (last_sg) {
                        if (!dwc3_prepare_last_sg(dep, req, trb_length, i))
                                break;
                } else {
                        /*
                         * Look ahead to check if we have enough TRBs for the
                         * next SG entry. If not, set interrupt on this TRB to
                         * resume preparing the next SG entry when more TRBs are
                         * free.
                         */
                        if (num_trbs_left == 1 || (needs_extra_trb &&
                                        num_trbs_left <= 2 &&
                                        sg_dma_len(sg_next(s)) >= length))
                                must_interrupt = true;

                        dwc3_prepare_one_trb(dep, req, trb_length, 1, i, false,
                                        must_interrupt);
                }

                /*
                 * There can be a situation where all sgs in sglist are not
                 * queued because of insufficient trb number. To handle this
                 * case, update start_sg to next sg to be queued, so that
                 * we have free trbs we can continue queuing from where we
                 * previously stopped
                 */
                if (!last_sg)
                        req->start_sg = sg_next(s);

                req->num_queued_sgs++;

                /*
                 * The number of pending SG entries may not correspond to the
                 * number of mapped SG entries. If all the data are queued, then
                 * don't include unused SG entries.
                 */
                if (length == 0) {
                        req->num_pending_sgs -= req->request.num_mapped_sgs - req->num_queued_sgs;
                        break;
                }

                if (must_interrupt)
                        break;
        }

        return req->num_trbs - num_trbs;
}

static int dwc3_prepare_trbs_linear(struct dwc3_ep *dep,
                struct dwc3_request *req)
{
        return dwc3_prepare_last_sg(dep, req, req->request.length, 0);
}

/*
 * dwc3_prepare_trbs - setup TRBs from requests
 * @dep: endpoint for which requests are being prepared
 *
 * The function goes through the requests list and sets up TRBs for the
 * transfers. The function returns once there are no more TRBs available or
 * it runs out of requests.
 *
 * Returns the number of TRBs prepared or negative errno.
 */
static int dwc3_prepare_trbs(struct dwc3_ep *dep)
{
        struct dwc3_request     *req, *n;
        int                     ret = 0;

        BUILD_BUG_ON_NOT_POWER_OF_2(DWC3_TRB_NUM);

        /*
         * We can get in a situation where there's a request in the started list
         * but there weren't enough TRBs to fully kick it in the first time
         * around, so it has been waiting for more TRBs to be freed up.
         *
         * In that case, we should check if we have a request with pending_sgs
         * in the started list and prepare TRBs for that request first,
         * otherwise we will prepare TRBs completely out of order and that will
         * break things.
         */
        list_for_each_entry(req, &dep->started_list, list) {
                if (req->num_pending_sgs > 0) {
                        ret = dwc3_prepare_trbs_sg(dep, req);
                        if (!ret || req->num_pending_sgs)
                                return ret;
                }

                if (!dwc3_calc_trbs_left(dep))
                        return ret;

                /*
                 * Don't prepare beyond a transfer. In DWC_usb32, its transfer
                 * burst capability may try to read and use TRBs beyond the
                 * active transfer instead of stopping.
                 */
                if (dep->stream_capable && req->request.is_last)
                        return ret;
        }

        list_for_each_entry_safe(req, n, &dep->pending_list, list) {
                struct dwc3     *dwc = dep->dwc;

                ret = usb_gadget_map_request_by_dev(dwc->sysdev, &req->request,
                                                    dep->direction);
                if (ret)
                        return ret;

                req->sg                 = req->request.sg;
                req->start_sg           = req->sg;
                req->num_queued_sgs     = 0;
                req->num_pending_sgs    = req->request.num_mapped_sgs;

                if (req->num_pending_sgs > 0) {
                        ret = dwc3_prepare_trbs_sg(dep, req);
                        if (req->num_pending_sgs)
                                return ret;
                } else {
                        ret = dwc3_prepare_trbs_linear(dep, req);
                }

                if (!ret || !dwc3_calc_trbs_left(dep))
                        return ret;

                /*
                 * Don't prepare beyond a transfer. In DWC_usb32, its transfer
                 * burst capability may try to read and use TRBs beyond the
                 * active transfer instead of stopping.
                 */
                if (dep->stream_capable && req->request.is_last)
                        return ret;
        }

        return ret;
}

static void dwc3_gadget_ep_cleanup_cancelled_requests(struct dwc3_ep *dep);

static int __dwc3_gadget_kick_transfer(struct dwc3_ep *dep)
{
        struct dwc3_gadget_ep_cmd_params params;
        struct dwc3_request             *req;
        int                             starting;
        int                             ret;
        u32                             cmd;

        /*
         * Note that it's normal to have no new TRBs prepared (i.e. ret == 0).
         * This happens when we need to stop and restart a transfer such as in
         * the case of reinitiating a stream or retrying an isoc transfer.
         */
        ret = dwc3_prepare_trbs(dep);
        if (ret < 0)
                return ret;

        starting = !(dep->flags & DWC3_EP_TRANSFER_STARTED);

        /*
         * If there's no new TRB prepared and we don't need to restart a
         * transfer, there's no need to update the transfer.
         */
        if (!ret && !starting)
                return ret;

        req = next_request(&dep->started_list);
        if (!req) {
                dep->flags |= DWC3_EP_PENDING_REQUEST;
                return 0;
        }

        memset(&params, 0, sizeof(params));

        if (starting) {
                params.param0 = upper_32_bits(req->trb_dma);
                params.param1 = lower_32_bits(req->trb_dma);
                cmd = DWC3_DEPCMD_STARTTRANSFER;

                if (dep->stream_capable)
                        cmd |= DWC3_DEPCMD_PARAM(req->request.stream_id);

                if (usb_endpoint_xfer_isoc(dep->endpoint.desc))
                        cmd |= DWC3_DEPCMD_PARAM(dep->frame_number);
        } else {
                cmd = DWC3_DEPCMD_UPDATETRANSFER |
                        DWC3_DEPCMD_PARAM(dep->resource_index);
        }

        ret = dwc3_send_gadget_ep_cmd(dep, cmd, &params);
        if (ret < 0) {
                struct dwc3_request *tmp;

                if (ret == -EAGAIN)
                        return ret;

                dwc3_stop_active_transfer(dep, true, true);

                list_for_each_entry_safe(req, tmp, &dep->started_list, list)
                        dwc3_gadget_move_cancelled_request(req);

                /* If ep isn't started, then there's no end transfer pending */
                if (!(dep->flags & DWC3_EP_END_TRANSFER_PENDING))
                        dwc3_gadget_ep_cleanup_cancelled_requests(dep);

                return ret;
        }

        if (dep->stream_capable && req->request.is_last)
                dep->flags |= DWC3_EP_WAIT_TRANSFER_COMPLETE;

        return 0;
}

static int __dwc3_gadget_get_frame(struct dwc3 *dwc)
{
        u32                     reg;

        reg = dwc3_readl(dwc->regs, DWC3_DSTS);
        return DWC3_DSTS_SOFFN(reg);
}

/**
 * dwc3_gadget_start_isoc_quirk - workaround invalid frame number
 * @dep: isoc endpoint
 *
 * This function tests for the correct combination of BIT[15:14] from the 16-bit
 * microframe number reported by the XferNotReady event for the future frame
 * number to start the isoc transfer.
 *
 * In DWC_usb31 version 1.70a-ea06 and prior, for highspeed and fullspeed
 * isochronous IN, BIT[15:14] of the 16-bit microframe number reported by the
 * XferNotReady event are invalid. The driver uses this number to schedule the
 * isochronous transfer and passes it to the START TRANSFER command. Because
 * this number is invalid, the command may fail. If BIT[15:14] matches the
 * internal 16-bit microframe, the START TRANSFER command will pass and the
 * transfer will start at the scheduled time, if it is off by 1, the command
 * will still pass, but the transfer will start 2 seconds in the future. For all
 * other conditions, the START TRANSFER command will fail with bus-expiry.
 *
 * In order to workaround this issue, we can test for the correct combination of
 * BIT[15:14] by sending START TRANSFER commands with different values of
 * BIT[15:14]: 'b00, 'b01, 'b10, and 'b11. Each combination is 2^14 uframe apart
 * (or 2 seconds). 4 seconds into the future will result in a bus-expiry status.
 * As the result, within the 4 possible combinations for BIT[15:14], there will
 * be 2 successful and 2 failure START COMMAND status. One of the 2 successful
 * command status will result in a 2-second delay start. The smaller BIT[15:14]
 * value is the correct combination.
 *
 * Since there are only 4 outcomes and the results are ordered, we can simply
 * test 2 START TRANSFER commands with BIT[15:14] combinations 'b00 and 'b01 to
 * deduce the smaller successful combination.
 *
 * Let test0 = test status for combination 'b00 and test1 = test status for 'b01
 * of BIT[15:14]. The correct combination is as follow:
 *
 * if test0 fails and test1 passes, BIT[15:14] is 'b01
 * if test0 fails and test1 fails, BIT[15:14] is 'b10
 * if test0 passes and test1 fails, BIT[15:14] is 'b11
 * if test0 passes and test1 passes, BIT[15:14] is 'b00
 *
 * Synopsys STAR 9001202023: Wrong microframe number for isochronous IN
 * endpoints.
 */
static int dwc3_gadget_start_isoc_quirk(struct dwc3_ep *dep)
{
        int cmd_status = 0;
        bool test0;
        bool test1;

        while (dep->combo_num < 2) {
                struct dwc3_gadget_ep_cmd_params params;
                u32 test_frame_number;
                u32 cmd;

                /*
                 * Check if we can start isoc transfer on the next interval or
                 * 4 uframes in the future with BIT[15:14] as dep->combo_num
                 */
                test_frame_number = dep->frame_number & DWC3_FRNUMBER_MASK;
                test_frame_number |= dep->combo_num << 14;
                test_frame_number += max_t(u32, 4, dep->interval);

                params.param0 = upper_32_bits(dep->dwc->bounce_addr);
                params.param1 = lower_32_bits(dep->dwc->bounce_addr);

                cmd = DWC3_DEPCMD_STARTTRANSFER;
                cmd |= DWC3_DEPCMD_PARAM(test_frame_number);
                cmd_status = dwc3_send_gadget_ep_cmd(dep, cmd, &params);

                /* Redo if some other failure beside bus-expiry is received */
                if (cmd_status && cmd_status != -EAGAIN) {
                        dep->start_cmd_status = 0;
                        dep->combo_num = 0;
                        return 0;
                }

                /* Store the first test status */
                if (dep->combo_num == 0)
                        dep->start_cmd_status = cmd_status;

                dep->combo_num++;

                /*
                 * End the transfer if the START_TRANSFER command is successful
                 * to wait for the next XferNotReady to test the command again
                 */
                if (cmd_status == 0) {
                        dwc3_stop_active_transfer(dep, true, true);
                        return 0;
                }
        }

        /* test0 and test1 are both completed at this point */
        test0 = (dep->start_cmd_status == 0);
        test1 = (cmd_status == 0);

        if (!test0 && test1)
                dep->combo_num = 1;
        else if (!test0 && !test1)
                dep->combo_num = 2;
        else if (test0 && !test1)
                dep->combo_num = 3;
        else if (test0 && test1)
                dep->combo_num = 0;

        dep->frame_number &= DWC3_FRNUMBER_MASK;
        dep->frame_number |= dep->combo_num << 14;
        dep->frame_number += max_t(u32, 4, dep->interval);

        /* Reinitialize test variables */
        dep->start_cmd_status = 0;
        dep->combo_num = 0;

        return __dwc3_gadget_kick_transfer(dep);
}

static int __dwc3_gadget_start_isoc(struct dwc3_ep *dep)
{
        const struct usb_endpoint_descriptor *desc = dep->endpoint.desc;
        struct dwc3 *dwc = dep->dwc;
        int ret;
        int i;

        if (list_empty(&dep->pending_list) &&
            list_empty(&dep->started_list)) {
                dep->flags |= DWC3_EP_PENDING_REQUEST;
                return -EAGAIN;
        }

        if (!dwc->dis_start_transfer_quirk &&
            (DWC3_VER_IS_PRIOR(DWC31, 170A) ||
             DWC3_VER_TYPE_IS_WITHIN(DWC31, 170A, EA01, EA06))) {
                if (dwc->gadget->speed <= USB_SPEED_HIGH && dep->direction)
                        return dwc3_gadget_start_isoc_quirk(dep);
        }

        if (desc->bInterval <= 14 &&
            dwc->gadget->speed >= USB_SPEED_HIGH) {
                u32 frame = __dwc3_gadget_get_frame(dwc);
                bool rollover = frame <
                                (dep->frame_number & DWC3_FRNUMBER_MASK);

                /*
                 * frame_number is set from XferNotReady and may be already
                 * out of date. DSTS only provides the lower 14 bit of the
                 * current frame number. So add the upper two bits of
                 * frame_number and handle a possible rollover.
                 * This will provide the correct frame_number unless more than
                 * rollover has happened since XferNotReady.
                 */

                dep->frame_number = (dep->frame_number & ~DWC3_FRNUMBER_MASK) |
                                     frame;
                if (rollover)
                        dep->frame_number += BIT(14);
        }

        for (i = 0; i < DWC3_ISOC_MAX_RETRIES; i++) {
                dep->frame_number = DWC3_ALIGN_FRAME(dep, i + 1);

                ret = __dwc3_gadget_kick_transfer(dep);
                if (ret != -EAGAIN)
                        break;
        }

        /*
         * After a number of unsuccessful start attempts due to bus-expiry
         * status, issue END_TRANSFER command and retry on the next XferNotReady
         * event.
         */
        if (ret == -EAGAIN) {
                struct dwc3_gadget_ep_cmd_params params;
                u32 cmd;

                cmd = DWC3_DEPCMD_ENDTRANSFER |
                        DWC3_DEPCMD_CMDIOC |
                        DWC3_DEPCMD_PARAM(dep->resource_index);

                dep->resource_index = 0;
                memset(&params, 0, sizeof(params));

                ret = dwc3_send_gadget_ep_cmd(dep, cmd, &params);
                if (!ret)
                        dep->flags |= DWC3_EP_END_TRANSFER_PENDING;
        }

        return ret;
}

static int __dwc3_gadget_ep_queue(struct dwc3_ep *dep, struct dwc3_request *req)
{
        struct dwc3             *dwc = dep->dwc;

        if (!dep->endpoint.desc || !dwc->pullups_connected) {
                dev_err(dwc->dev, "%s: can't queue to disabled endpoint\n",
                                dep->name);
                return -ESHUTDOWN;
        }

        if (WARN(req->dep != dep, "request %pK belongs to '%s'\n",
                                &req->request, req->dep->name))
                return -EINVAL;

        if (WARN(req->status < DWC3_REQUEST_STATUS_COMPLETED,
                                "%s: request %pK already in flight\n",
                                dep->name, &req->request))
                return -EINVAL;

        pm_runtime_get(dwc->dev);

        req->request.actual     = 0;
        req->request.status     = -EINPROGRESS;

        trace_dwc3_ep_queue(req);

        list_add_tail(&req->list, &dep->pending_list);
        req->status = DWC3_REQUEST_STATUS_QUEUED;

        if (dep->flags & DWC3_EP_WAIT_TRANSFER_COMPLETE)
                return 0;

        /*
         * Start the transfer only after the END_TRANSFER is completed
         * and endpoint STALL is cleared.
         */
        if ((dep->flags & DWC3_EP_END_TRANSFER_PENDING) ||
            (dep->flags & DWC3_EP_WEDGE) ||
            (dep->flags & DWC3_EP_STALL)) {
                dep->flags |= DWC3_EP_DELAY_START;
                return 0;
        }

        /*
         * NOTICE: Isochronous endpoints should NEVER be prestarted. We must
         * wait for a XferNotReady event so we will know what's the current
         * (micro-)frame number.
         *
         * Without this trick, we are very, very likely gonna get Bus Expiry
         * errors which will force us issue EndTransfer command.
         */
        if (usb_endpoint_xfer_isoc(dep->endpoint.desc)) {
                if (!(dep->flags & DWC3_EP_PENDING_REQUEST) &&
                                !(dep->flags & DWC3_EP_TRANSFER_STARTED))
                        return 0;

                if ((dep->flags & DWC3_EP_PENDING_REQUEST)) {
                        if (!(dep->flags & DWC3_EP_TRANSFER_STARTED))
                                return __dwc3_gadget_start_isoc(dep);
                }
        }

        return __dwc3_gadget_kick_transfer(dep);
}

static int dwc3_gadget_ep_queue(struct usb_ep *ep, struct usb_request *request,
        gfp_t gfp_flags)
{
        struct dwc3_request             *req = to_dwc3_request(request);
        struct dwc3_ep                  *dep = to_dwc3_ep(ep);
        struct dwc3                     *dwc = dep->dwc;

        unsigned long                   flags;

        int                             ret;

        spin_lock_irqsave(&dwc->lock, flags);
        ret = __dwc3_gadget_ep_queue(dep, req);
        spin_unlock_irqrestore(&dwc->lock, flags);

        return ret;
}

static void dwc3_gadget_ep_skip_trbs(struct dwc3_ep *dep, struct dwc3_request *req)
{
        int i;

        /* If req->trb is not set, then the request has not started */
        if (!req->trb)
                return;

        /*
         * If request was already started, this means we had to
         * stop the transfer. With that we also need to ignore
         * all TRBs used by the request, however TRBs can only
         * be modified after completion of END_TRANSFER
         * command. So what we do here is that we wait for
         * END_TRANSFER completion and only after that, we jump
         * over TRBs by clearing HWO and incrementing dequeue
         * pointer.
         */
        for (i = 0; i < req->num_trbs; i++) {
                struct dwc3_trb *trb;

                trb = &dep->trb_pool[dep->trb_dequeue];
                trb->ctrl &= ~DWC3_TRB_CTRL_HWO;
                dwc3_ep_inc_deq(dep);
        }

        req->num_trbs = 0;
}

static void dwc3_gadget_ep_cleanup_cancelled_requests(struct dwc3_ep *dep)
{
        struct dwc3_request             *req;
        struct dwc3_request             *tmp;

        list_for_each_entry_safe(req, tmp, &dep->cancelled_list, list) {
                dwc3_gadget_ep_skip_trbs(dep, req);
                dwc3_gadget_giveback(dep, req, -ECONNRESET);
        }
}

static int dwc3_gadget_ep_dequeue(struct usb_ep *ep,
                struct usb_request *request)
{
        struct dwc3_request             *req = to_dwc3_request(request);
        struct dwc3_request             *r = NULL;

        struct dwc3_ep                  *dep = to_dwc3_ep(ep);
        struct dwc3                     *dwc = dep->dwc;

        unsigned long                   flags;
        int                             ret = 0;

        trace_dwc3_ep_dequeue(req);

        spin_lock_irqsave(&dwc->lock, flags);

        list_for_each_entry(r, &dep->cancelled_list, list) {
                if (r == req)
                        goto out;
        }

        list_for_each_entry(r, &dep->pending_list, list) {
                if (r == req) {
                        dwc3_gadget_giveback(dep, req, -ECONNRESET);
                        goto out;
                }
        }

        list_for_each_entry(r, &dep->started_list, list) {
                if (r == req) {
                        struct dwc3_request *t;

                        /* wait until it is processed */
                        dwc3_stop_active_transfer(dep, true, true);

                        /*
                         * Remove any started request if the transfer is
                         * cancelled.
                         */
                        list_for_each_entry_safe(r, t, &dep->started_list, list)
                                dwc3_gadget_move_cancelled_request(r);

                        dep->flags &= ~DWC3_EP_WAIT_TRANSFER_COMPLETE;

                        goto out;
                }
        }

        dev_err(dwc->dev, "request %pK was not queued to %s\n",
                request, ep->name);
        ret = -EINVAL;
out:
        spin_unlock_irqrestore(&dwc->lock, flags);

        return ret;
}

int __dwc3_gadget_ep_set_halt(struct dwc3_ep *dep, int value, int protocol)
{
        struct dwc3_gadget_ep_cmd_params        params;
        struct dwc3                             *dwc = dep->dwc;
        struct dwc3_request                     *req;
        struct dwc3_request                     *tmp;
        int                                     ret;

        if (usb_endpoint_xfer_isoc(dep->endpoint.desc)) {
                dev_err(dwc->dev, "%s is of Isochronous type\n", dep->name);
                return -EINVAL;
        }

        memset(&params, 0x00, sizeof(params));

        if (value) {
                struct dwc3_trb *trb;

                unsigned int transfer_in_flight;
                unsigned int started;

                if (dep->number > 1)
                        trb = dwc3_ep_prev_trb(dep, dep->trb_enqueue);
                else
                        trb = &dwc->ep0_trb[dep->trb_enqueue];

                transfer_in_flight = trb->ctrl & DWC3_TRB_CTRL_HWO;
                started = !list_empty(&dep->started_list);

                if (!protocol && ((dep->direction && transfer_in_flight) ||
                                (!dep->direction && started))) {
                        return -EAGAIN;
                }

                ret = dwc3_send_gadget_ep_cmd(dep, DWC3_DEPCMD_SETSTALL,
                                &params);
                if (ret)
                        dev_err(dwc->dev, "failed to set STALL on %s\n",
                                        dep->name);
                else
                        dep->flags |= DWC3_EP_STALL;
        } else {
                /*
                 * Don't issue CLEAR_STALL command to control endpoints. The
                 * controller automatically clears the STALL when it receives
                 * the SETUP token.
                 */
                if (dep->number <= 1) {
                        dep->flags &= ~(DWC3_EP_STALL | DWC3_EP_WEDGE);
                        return 0;
                }

                dwc3_stop_active_transfer(dep, true, true);

                list_for_each_entry_safe(req, tmp, &dep->started_list, list)
                        dwc3_gadget_move_cancelled_request(req);

                if (dep->flags & DWC3_EP_END_TRANSFER_PENDING) {
                        dep->flags |= DWC3_EP_PENDING_CLEAR_STALL;
                        return 0;
                }

                dwc3_gadget_ep_cleanup_cancelled_requests(dep);

                ret = dwc3_send_clear_stall_ep_cmd(dep);
                if (ret) {
                        dev_err(dwc->dev, "failed to clear STALL on %s\n",
                                        dep->name);
                        return ret;
                }

                dep->flags &= ~(DWC3_EP_STALL | DWC3_EP_WEDGE);

                if ((dep->flags & DWC3_EP_DELAY_START) &&
                    !usb_endpoint_xfer_isoc(dep->endpoint.desc))
                        __dwc3_gadget_kick_transfer(dep);

                dep->flags &= ~DWC3_EP_DELAY_START;
        }

        return ret;
}

static int dwc3_gadget_ep_set_halt(struct usb_ep *ep, int value)
{
        struct dwc3_ep                  *dep = to_dwc3_ep(ep);
        struct dwc3                     *dwc = dep->dwc;

        unsigned long                   flags;

        int                             ret;

        spin_lock_irqsave(&dwc->lock, flags);
        ret = __dwc3_gadget_ep_set_halt(dep, value, false);
        spin_unlock_irqrestore(&dwc->lock, flags);

        return ret;
}

static int dwc3_gadget_ep_set_wedge(struct usb_ep *ep)
{
        struct dwc3_ep                  *dep = to_dwc3_ep(ep);
        struct dwc3                     *dwc = dep->dwc;
        unsigned long                   flags;
        int                             ret;

        spin_lock_irqsave(&dwc->lock, flags);
        dep->flags |= DWC3_EP_WEDGE;

        if (dep->number == 0 || dep->number == 1)
                ret = __dwc3_gadget_ep0_set_halt(ep, 1);
        else
                ret = __dwc3_gadget_ep_set_halt(dep, 1, false);
        spin_unlock_irqrestore(&dwc->lock, flags);

        return ret;
}

/* -------------------------------------------------------------------------- */

static struct usb_endpoint_descriptor dwc3_gadget_ep0_desc = {
        .bLength        = USB_DT_ENDPOINT_SIZE,
        .bDescriptorType = USB_DT_ENDPOINT,
        .bmAttributes   = USB_ENDPOINT_XFER_CONTROL,
};

static const struct usb_ep_ops dwc3_gadget_ep0_ops = {
        .enable         = dwc3_gadget_ep0_enable,
        .disable        = dwc3_gadget_ep0_disable,
        .alloc_request  = dwc3_gadget_ep_alloc_request,
        .free_request   = dwc3_gadget_ep_free_request,
        .queue          = dwc3_gadget_ep0_queue,
        .dequeue        = dwc3_gadget_ep_dequeue,
        .set_halt       = dwc3_gadget_ep0_set_halt,
        .set_wedge      = dwc3_gadget_ep_set_wedge,
};

static const struct usb_ep_ops dwc3_gadget_ep_ops = {
        .enable         = dwc3_gadget_ep_enable,
        .disable        = dwc3_gadget_ep_disable,
        .alloc_request  = dwc3_gadget_ep_alloc_request,
        .free_request   = dwc3_gadget_ep_free_request,
        .queue          = dwc3_gadget_ep_queue,
        .dequeue        = dwc3_gadget_ep_dequeue,
        .set_halt       = dwc3_gadget_ep_set_halt,
        .set_wedge      = dwc3_gadget_ep_set_wedge,
};

/* -------------------------------------------------------------------------- */

static int dwc3_gadget_get_frame(struct usb_gadget *g)
{
        struct dwc3             *dwc = gadget_to_dwc(g);

        return __dwc3_gadget_get_frame(dwc);
}

static int __dwc3_gadget_wakeup(struct dwc3 *dwc)
{
        int                     retries;

        int                     ret;
        u32                     reg;

        u8                      link_state;

        /*
         * According to the Databook Remote wakeup request should
         * be issued only when the device is in early suspend state.
         *
         * We can check that via USB Link State bits in DSTS register.
         */
        reg = dwc3_readl(dwc->regs, DWC3_DSTS);

        link_state = DWC3_DSTS_USBLNKST(reg);

        switch (link_state) {
        case DWC3_LINK_STATE_RESET:
        case DWC3_LINK_STATE_RX_DET:    /* in HS, means Early Suspend */
        case DWC3_LINK_STATE_U3:        /* in HS, means SUSPEND */
        case DWC3_LINK_STATE_RESUME:
                break;
        default:
                return -EINVAL;
        }

        ret = dwc3_gadget_set_link_state(dwc, DWC3_LINK_STATE_RECOV);
        if (ret < 0) {
                dev_err(dwc->dev, "failed to put link in Recovery\n");
                return ret;
        }

        /* Recent versions do this automatically */
        if (DWC3_VER_IS_PRIOR(DWC3, 194A)) {
                /* write zeroes to Link Change Request */
                reg = dwc3_readl(dwc->regs, DWC3_DCTL);
                reg &= ~DWC3_DCTL_ULSTCHNGREQ_MASK;
                dwc3_writel(dwc->regs, DWC3_DCTL, reg);
        }

        /* poll until Link State changes to ON */
        retries = 20000;

        while (retries--) {
                reg = dwc3_readl(dwc->regs, DWC3_DSTS);

                /* in HS, means ON */
                if (DWC3_DSTS_USBLNKST(reg) == DWC3_LINK_STATE_U0)
                        break;
        }

        if (DWC3_DSTS_USBLNKST(reg) != DWC3_LINK_STATE_U0) {
                dev_err(dwc->dev, "failed to send remote wakeup\n");
                return -EINVAL;
        }

        return 0;
}

static int dwc3_gadget_wakeup(struct usb_gadget *g)
{
        struct dwc3             *dwc = gadget_to_dwc(g);
        unsigned long           flags;
        int                     ret;

        spin_lock_irqsave(&dwc->lock, flags);
        ret = __dwc3_gadget_wakeup(dwc);
        spin_unlock_irqrestore(&dwc->lock, flags);

        return ret;
}

static int dwc3_gadget_set_selfpowered(struct usb_gadget *g,
                int is_selfpowered)
{
        struct dwc3             *dwc = gadget_to_dwc(g);
        unsigned long           flags;

        spin_lock_irqsave(&dwc->lock, flags);
        g->is_selfpowered = !!is_selfpowered;
        spin_unlock_irqrestore(&dwc->lock, flags);

        return 0;
}

static void dwc3_stop_active_transfers(struct dwc3 *dwc)
{
        u32 epnum;

        for (epnum = 2; epnum < dwc->num_eps; epnum++) {
                struct dwc3_ep *dep;

                dep = dwc->eps[epnum];
                if (!dep)
                        continue;

                dwc3_remove_requests(dwc, dep);
        }
}

static int dwc3_gadget_run_stop(struct dwc3 *dwc, int is_on, int suspend)
{
        u32                     reg;
        u32                     timeout = 500;

        if (pm_runtime_suspended(dwc->dev))
                return 0;

        reg = dwc3_readl(dwc->regs, DWC3_DCTL);
        if (is_on) {
                if (DWC3_VER_IS_WITHIN(DWC3, ANY, 187A)) {
                        reg &= ~DWC3_DCTL_TRGTULST_MASK;
                        reg |= DWC3_DCTL_TRGTULST_RX_DET;
                }

                if (!DWC3_VER_IS_PRIOR(DWC3, 194A))
                        reg &= ~DWC3_DCTL_KEEP_CONNECT;
                reg |= DWC3_DCTL_RUN_STOP;

                if (dwc->has_hibernation)
                        reg |= DWC3_DCTL_KEEP_CONNECT;

                dwc->pullups_connected = true;
        } else {
                reg &= ~DWC3_DCTL_RUN_STOP;

                if (dwc->has_hibernation && !suspend)
                        reg &= ~DWC3_DCTL_KEEP_CONNECT;

                dwc->pullups_connected = false;
        }

        dwc3_gadget_dctl_write_safe(dwc, reg);

        do {
                reg = dwc3_readl(dwc->regs, DWC3_DSTS);
                reg &= DWC3_DSTS_DEVCTRLHLT;
        } while (--timeout && !(!is_on ^ !reg));

        if (!timeout)
                return -ETIMEDOUT;

        return 0;
}

static void dwc3_gadget_disable_irq(struct dwc3 *dwc);
static void __dwc3_gadget_stop(struct dwc3 *dwc);
static int __dwc3_gadget_start(struct dwc3 *dwc);

static int dwc3_gadget_pullup(struct usb_gadget *g, int is_on)
{
        struct dwc3             *dwc = gadget_to_dwc(g);
        unsigned long           flags;
        int                     ret;

        is_on = !!is_on;

        /*
         * Per databook, when we want to stop the gadget, if a control transfer
         * is still in process, complete it and get the core into setup phase.
         */
        if (!is_on && dwc->ep0state != EP0_SETUP_PHASE) {
                reinit_completion(&dwc->ep0_in_setup);

                ret = wait_for_completion_timeout(&dwc->ep0_in_setup,
                                msecs_to_jiffies(DWC3_PULL_UP_TIMEOUT));
                if (ret == 0) {
                        dev_err(dwc->dev, "timed out waiting for SETUP phase\n");
                        return -ETIMEDOUT;
                }
        }

        /*
         * Synchronize any pending event handling before executing the controller
         * halt routine.
         */
        if (!is_on) {
                dwc3_gadget_disable_irq(dwc);
                synchronize_irq(dwc->irq_gadget);
        }

        spin_lock_irqsave(&dwc->lock, flags);

        if (!is_on) {
                u32 count;

                /*
                 * In the Synopsis DesignWare Cores USB3 Databook Rev. 3.30a
                 * Section 4.1.8 Table 4-7, it states that for a device-initiated
                 * disconnect, the SW needs to ensure that it sends "a DEPENDXFER
                 * command for any active transfers" before clearing the RunStop
                 * bit.
                 */
                dwc3_stop_active_transfers(dwc);
                __dwc3_gadget_stop(dwc);

                /*
                 * In the Synopsis DesignWare Cores USB3 Databook Rev. 3.30a
                 * Section 1.3.4, it mentions that for the DEVCTRLHLT bit, the
                 * "software needs to acknowledge the events that are generated
                 * (by writing to GEVNTCOUNTn) while it is waiting for this bit
                 * to be set to '1'."
                 */
                count = dwc3_readl(dwc->regs, DWC3_GEVNTCOUNT(0));
                count &= DWC3_GEVNTCOUNT_MASK;
                if (count > 0) {
                        dwc3_writel(dwc->regs, DWC3_GEVNTCOUNT(0), count);
                        dwc->ev_buf->lpos = (dwc->ev_buf->lpos + count) %
                                                dwc->ev_buf->length;
                }
        } else {
                __dwc3_gadget_start(dwc);
        }

        ret = dwc3_gadget_run_stop(dwc, is_on, false);
        spin_unlock_irqrestore(&dwc->lock, flags);

        return ret;
}

static void dwc3_gadget_enable_irq(struct dwc3 *dwc)
{
        u32                     reg;

        /* Enable all but Start and End of Frame IRQs */
        reg = (DWC3_DEVTEN_VNDRDEVTSTRCVEDEN |
                        DWC3_DEVTEN_EVNTOVERFLOWEN |
                        DWC3_DEVTEN_CMDCMPLTEN |
                        DWC3_DEVTEN_ERRTICERREN |
                        DWC3_DEVTEN_WKUPEVTEN |
                        DWC3_DEVTEN_CONNECTDONEEN |
                        DWC3_DEVTEN_USBRSTEN |
                        DWC3_DEVTEN_DISCONNEVTEN);

        if (DWC3_VER_IS_PRIOR(DWC3, 250A))
                reg |= DWC3_DEVTEN_ULSTCNGEN;

        dwc3_writel(dwc->regs, DWC3_DEVTEN, reg);
}

static void dwc3_gadget_disable_irq(struct dwc3 *dwc)
{
        /* mask all interrupts */
        dwc3_writel(dwc->regs, DWC3_DEVTEN, 0x00);
}

static irqreturn_t dwc3_interrupt(int irq, void *_dwc);
static irqreturn_t dwc3_thread_interrupt(int irq, void *_dwc);

/**
 * dwc3_gadget_setup_nump - calculate and initialize NUMP field of %DWC3_DCFG
 * @dwc: pointer to our context structure
 *
 * The following looks like complex but it's actually very simple. In order to
 * calculate the number of packets we can burst at once on OUT transfers, we're
 * gonna use RxFIFO size.
 *
 * To calculate RxFIFO size we need two numbers:
 * MDWIDTH = size, in bits, of the internal memory bus
 * RAM2_DEPTH = depth, in MDWIDTH, of internal RAM2 (where RxFIFO sits)
 *
 * Given these two numbers, the formula is simple:
 *
 * RxFIFO Size = (RAM2_DEPTH * MDWIDTH / 8) - 24 - 16;
 *
 * 24 bytes is for 3x SETUP packets
 * 16 bytes is a clock domain crossing tolerance
 *
 * Given RxFIFO Size, NUMP = RxFIFOSize / 1024;
 */
static void dwc3_gadget_setup_nump(struct dwc3 *dwc)
{
        u32 ram2_depth;
        u32 mdwidth;
        u32 nump;
        u32 reg;

        ram2_depth = DWC3_GHWPARAMS7_RAM2_DEPTH(dwc->hwparams.hwparams7);
        mdwidth = DWC3_GHWPARAMS0_MDWIDTH(dwc->hwparams.hwparams0);
        if (DWC3_IP_IS(DWC32))
                mdwidth += DWC3_GHWPARAMS6_MDWIDTH(dwc->hwparams.hwparams6);

        nump = ((ram2_depth * mdwidth / 8) - 24 - 16) / 1024;
        nump = min_t(u32, nump, 16);

        /* update NumP */
        reg = dwc3_readl(dwc->regs, DWC3_DCFG);
        reg &= ~DWC3_DCFG_NUMP_MASK;
        reg |= nump << DWC3_DCFG_NUMP_SHIFT;
        dwc3_writel(dwc->regs, DWC3_DCFG, reg);
}

static int __dwc3_gadget_start(struct dwc3 *dwc)
{
        struct dwc3_ep          *dep;
        int                     ret = 0;
        u32                     reg;

        /*
         * Use IMOD if enabled via dwc->imod_interval. Otherwise, if
         * the core supports IMOD, disable it.
         */
        if (dwc->imod_interval) {
                dwc3_writel(dwc->regs, DWC3_DEV_IMOD(0), dwc->imod_interval);
                dwc3_writel(dwc->regs, DWC3_GEVNTCOUNT(0), DWC3_GEVNTCOUNT_EHB);
        } else if (dwc3_has_imod(dwc)) {
                dwc3_writel(dwc->regs, DWC3_DEV_IMOD(0), 0);
        }

        /*
         * We are telling dwc3 that we want to use DCFG.NUMP as ACK TP's NUMP
         * field instead of letting dwc3 itself calculate that automatically.
         *
         * This way, we maximize the chances that we'll be able to get several
         * bursts of data without going through any sort of endpoint throttling.
         */
        reg = dwc3_readl(dwc->regs, DWC3_GRXTHRCFG);
        if (DWC3_IP_IS(DWC3))
                reg &= ~DWC3_GRXTHRCFG_PKTCNTSEL;
        else
                reg &= ~DWC31_GRXTHRCFG_PKTCNTSEL;

        dwc3_writel(dwc->regs, DWC3_GRXTHRCFG, reg);

        dwc3_gadget_setup_nump(dwc);

        /* Start with SuperSpeed Default */
        dwc3_gadget_ep0_desc.wMaxPacketSize = cpu_to_le16(512);

        dep = dwc->eps[0];
        ret = __dwc3_gadget_ep_enable(dep, DWC3_DEPCFG_ACTION_INIT);
        if (ret) {
                dev_err(dwc->dev, "failed to enable %s\n", dep->name);
                goto err0;
        }

        dep = dwc->eps[1];
        ret = __dwc3_gadget_ep_enable(dep, DWC3_DEPCFG_ACTION_INIT);
        if (ret) {
                dev_err(dwc->dev, "failed to enable %s\n", dep->name);
                goto err1;
        }

        /* begin to receive SETUP packets */
        dwc->ep0state = EP0_SETUP_PHASE;
        dwc->link_state = DWC3_LINK_STATE_SS_DIS;
        dwc3_ep0_out_start(dwc);

        dwc3_gadget_enable_irq(dwc);

        return 0;

err1:
        __dwc3_gadget_ep_disable(dwc->eps[0]);

err0:
        return ret;
}

static int dwc3_gadget_start(struct usb_gadget *g,
                struct usb_gadget_driver *driver)
{
        struct dwc3             *dwc = gadget_to_dwc(g);
        unsigned long           flags;
        int                     ret = 0;
        int                     irq;

        irq = dwc->irq_gadget;
        ret = request_threaded_irq(irq, dwc3_interrupt, dwc3_thread_interrupt,
                        IRQF_SHARED, "dwc3", dwc->ev_buf);
        if (ret) {
                dev_err(dwc->dev, "failed to request irq #%d --> %d\n",
                                irq, ret);
                goto err0;
        }

        spin_lock_irqsave(&dwc->lock, flags);
        if (dwc->gadget_driver) {
                dev_err(dwc->dev, "%s is already bound to %s\n",
                                dwc->gadget->name,
                                dwc->gadget_driver->driver.name);
                ret = -EBUSY;
                goto err1;
        }

        dwc->gadget_driver      = driver;
        spin_unlock_irqrestore(&dwc->lock, flags);

        return 0;

err1:
        spin_unlock_irqrestore(&dwc->lock, flags);
        free_irq(irq, dwc);

err0:
        return ret;
}

static void __dwc3_gadget_stop(struct dwc3 *dwc)
{
        dwc3_gadget_disable_irq(dwc);
        __dwc3_gadget_ep_disable(dwc->eps[0]);
        __dwc3_gadget_ep_disable(dwc->eps[1]);
}

static int dwc3_gadget_stop(struct usb_gadget *g)
{
        struct dwc3             *dwc = gadget_to_dwc(g);
        unsigned long           flags;

        spin_lock_irqsave(&dwc->lock, flags);
        dwc->gadget_driver      = NULL;
        spin_unlock_irqrestore(&dwc->lock, flags);

        free_irq(dwc->irq_gadget, dwc->ev_buf);

        return 0;
}

static void dwc3_gadget_config_params(struct usb_gadget *g,
                                      struct usb_dcd_config_params *params)
{
        struct dwc3             *dwc = gadget_to_dwc(g);

        params->besl_baseline = USB_DEFAULT_BESL_UNSPECIFIED;
        params->besl_deep = USB_DEFAULT_BESL_UNSPECIFIED;

        /* Recommended BESL */
        if (!dwc->dis_enblslpm_quirk) {
                /*
                 * If the recommended BESL baseline is 0 or if the BESL deep is
                 * less than 2, Microsoft's Windows 10 host usb stack will issue
                 * a usb reset immediately after it receives the extended BOS
                 * descriptor and the enumeration will fail. To maintain
                 * compatibility with the Windows' usb stack, let's set the
                 * recommended BESL baseline to 1 and clamp the BESL deep to be
                 * within 2 to 15.
                 */
                params->besl_baseline = 1;
                if (dwc->is_utmi_l1_suspend)
                        params->besl_deep =
                                clamp_t(u8, dwc->hird_threshold, 2, 15);
        }

        /* U1 Device exit Latency */
        if (dwc->dis_u1_entry_quirk)
                params->bU1devExitLat = 0;
        else
                params->bU1devExitLat = DWC3_DEFAULT_U1_DEV_EXIT_LAT;

        /* U2 Device exit Latency */
        if (dwc->dis_u2_entry_quirk)
                params->bU2DevExitLat = 0;
        else
                params->bU2DevExitLat =
                                cpu_to_le16(DWC3_DEFAULT_U2_DEV_EXIT_LAT);
}

static void dwc3_gadget_set_speed(struct usb_gadget *g,
                                  enum usb_device_speed speed)
{
        struct dwc3             *dwc = gadget_to_dwc(g);
        unsigned long           flags;
        u32                     reg;

        spin_lock_irqsave(&dwc->lock, flags);
        reg = dwc3_readl(dwc->regs, DWC3_DCFG);
        reg &= ~(DWC3_DCFG_SPEED_MASK);

        /*
         * WORKAROUND: DWC3 revision < 2.20a have an issue
         * which would cause metastability state on Run/Stop
         * bit if we try to force the IP to USB2-only mode.
         *
         * Because of that, we cannot configure the IP to any
         * speed other than the SuperSpeed
         *
         * Refers to:
         *
         * STAR#9000525659: Clock Domain Crossing on DCTL in
         * USB 2.0 Mode
         */
        if (DWC3_VER_IS_PRIOR(DWC3, 220A) &&
            !dwc->dis_metastability_quirk) {
                reg |= DWC3_DCFG_SUPERSPEED;
        } else {
                switch (speed) {
                case USB_SPEED_LOW:
                        reg |= DWC3_DCFG_LOWSPEED;
                        break;
                case USB_SPEED_FULL:
                        reg |= DWC3_DCFG_FULLSPEED;
                        break;
                case USB_SPEED_HIGH:
                        reg |= DWC3_DCFG_HIGHSPEED;
                        break;
                case USB_SPEED_SUPER:
                        reg |= DWC3_DCFG_SUPERSPEED;
                        break;
                case USB_SPEED_SUPER_PLUS:
                        if (DWC3_IP_IS(DWC3))
                                reg |= DWC3_DCFG_SUPERSPEED;
                        else
                                reg |= DWC3_DCFG_SUPERSPEED_PLUS;
                        break;
                default:
                        dev_err(dwc->dev, "invalid speed (%d)\n", speed);

                        if (DWC3_IP_IS(DWC3))
                                reg |= DWC3_DCFG_SUPERSPEED;
                        else
                                reg |= DWC3_DCFG_SUPERSPEED_PLUS;
                }
        }
        dwc3_writel(dwc->regs, DWC3_DCFG, reg);

        spin_unlock_irqrestore(&dwc->lock, flags);
}

static const struct usb_gadget_ops dwc3_gadget_ops = {
        .get_frame              = dwc3_gadget_get_frame,
        .wakeup                 = dwc3_gadget_wakeup,
        .set_selfpowered        = dwc3_gadget_set_selfpowered,
        .pullup                 = dwc3_gadget_pullup,
        .udc_start              = dwc3_gadget_start,
        .udc_stop               = dwc3_gadget_stop,
        .udc_set_speed          = dwc3_gadget_set_speed,
        .get_config_params      = dwc3_gadget_config_params,
};

/* -------------------------------------------------------------------------- */

static int dwc3_gadget_init_control_endpoint(struct dwc3_ep *dep)
{
        struct dwc3 *dwc = dep->dwc;

        usb_ep_set_maxpacket_limit(&dep->endpoint, 512);
        dep->endpoint.maxburst = 1;
        dep->endpoint.ops = &dwc3_gadget_ep0_ops;
        if (!dep->direction)
                dwc->gadget->ep0 = &dep->endpoint;

        dep->endpoint.caps.type_control = true;

        return 0;
}

static int dwc3_gadget_init_in_endpoint(struct dwc3_ep *dep)
{
        struct dwc3 *dwc = dep->dwc;
        int mdwidth;
        int size;

        mdwidth = DWC3_MDWIDTH(dwc->hwparams.hwparams0);
        if (DWC3_IP_IS(DWC32))
                mdwidth += DWC3_GHWPARAMS6_MDWIDTH(dwc->hwparams.hwparams6);

        /* MDWIDTH is represented in bits, we need it in bytes */
        mdwidth /= 8;

        size = dwc3_readl(dwc->regs, DWC3_GTXFIFOSIZ(dep->number >> 1));
        if (DWC3_IP_IS(DWC3))
                size = DWC3_GTXFIFOSIZ_TXFDEP(size);
        else
                size = DWC31_GTXFIFOSIZ_TXFDEP(size);

        /* FIFO Depth is in MDWDITH bytes. Multiply */
        size *= mdwidth;

        /*
         * To meet performance requirement, a minimum TxFIFO size of 3x
         * MaxPacketSize is recommended for endpoints that support burst and a
         * minimum TxFIFO size of 2x MaxPacketSize for endpoints that don't
         * support burst. Use those numbers and we can calculate the max packet
         * limit as below.
         */
        if (dwc->maximum_speed >= USB_SPEED_SUPER)
                size /= 3;
        else
                size /= 2;

        usb_ep_set_maxpacket_limit(&dep->endpoint, size);

        dep->endpoint.max_streams = 16;
        dep->endpoint.ops = &dwc3_gadget_ep_ops;
        list_add_tail(&dep->endpoint.ep_list,
                        &dwc->gadget->ep_list);
        dep->endpoint.caps.type_iso = true;
        dep->endpoint.caps.type_bulk = true;
        dep->endpoint.caps.type_int = true;

        return dwc3_alloc_trb_pool(dep);
}

static int dwc3_gadget_init_out_endpoint(struct dwc3_ep *dep)
{
        struct dwc3 *dwc = dep->dwc;
        int mdwidth;
        int size;

        mdwidth = DWC3_MDWIDTH(dwc->hwparams.hwparams0);
        if (DWC3_IP_IS(DWC32))
                mdwidth += DWC3_GHWPARAMS6_MDWIDTH(dwc->hwparams.hwparams6);

        /* MDWIDTH is represented in bits, convert to bytes */
        mdwidth /= 8;

        /* All OUT endpoints share a single RxFIFO space */
        size = dwc3_readl(dwc->regs, DWC3_GRXFIFOSIZ(0));
        if (DWC3_IP_IS(DWC3))
                size = DWC3_GRXFIFOSIZ_RXFDEP(size);
        else
                size = DWC31_GRXFIFOSIZ_RXFDEP(size);

        /* FIFO depth is in MDWDITH bytes */
        size *= mdwidth;

        /*
         * To meet performance requirement, a minimum recommended RxFIFO size
         * is defined as follow:
         * RxFIFO size >= (3 x MaxPacketSize) +
         * (3 x 8 bytes setup packets size) + (16 bytes clock crossing margin)
         *
         * Then calculate the max packet limit as below.
         */
        size -= (3 * 8) + 16;
        if (size < 0)
                size = 0;
        else
                size /= 3;

        usb_ep_set_maxpacket_limit(&dep->endpoint, size);
        dep->endpoint.max_streams = 16;
        dep->endpoint.ops = &dwc3_gadget_ep_ops;
        list_add_tail(&dep->endpoint.ep_list,
                        &dwc->gadget->ep_list);
        dep->endpoint.caps.type_iso = true;
        dep->endpoint.caps.type_bulk = true;
        dep->endpoint.caps.type_int = true;

        return dwc3_alloc_trb_pool(dep);
}

static int dwc3_gadget_init_endpoint(struct dwc3 *dwc, u8 epnum)
{
        struct dwc3_ep                  *dep;
        bool                            direction = epnum & 1;
        int                             ret;
        u8                              num = epnum >> 1;

        dep = kzalloc(sizeof(*dep), GFP_KERNEL);
        if (!dep)
                return -ENOMEM;

        dep->dwc = dwc;
        dep->number = epnum;
        dep->direction = direction;
        dep->regs = dwc->regs + DWC3_DEP_BASE(epnum);
        dwc->eps[epnum] = dep;
        dep->combo_num = 0;
        dep->start_cmd_status = 0;

        snprintf(dep->name, sizeof(dep->name), "ep%u%s", num,
                        direction ? "in" : "out");

        dep->endpoint.name = dep->name;

        if (!(dep->number > 1)) {
                dep->endpoint.desc = &dwc3_gadget_ep0_desc;
                dep->endpoint.comp_desc = NULL;
        }

        if (num == 0)
                ret = dwc3_gadget_init_control_endpoint(dep);
        else if (direction)
                ret = dwc3_gadget_init_in_endpoint(dep);
        else
                ret = dwc3_gadget_init_out_endpoint(dep);

        if (ret)
                return ret;

        dep->endpoint.caps.dir_in = direction;
        dep->endpoint.caps.dir_out = !direction;

        INIT_LIST_HEAD(&dep->pending_list);
        INIT_LIST_HEAD(&dep->started_list);
        INIT_LIST_HEAD(&dep->cancelled_list);

        return 0;
}

static int dwc3_gadget_init_endpoints(struct dwc3 *dwc, u8 total)
{
        u8                              epnum;

        INIT_LIST_HEAD(&dwc->gadget->ep_list);

        for (epnum = 0; epnum < total; epnum++) {
                int                     ret;

                ret = dwc3_gadget_init_endpoint(dwc, epnum);
                if (ret)
                        return ret;
        }

        return 0;
}

static void dwc3_gadget_free_endpoints(struct dwc3 *dwc)
{
        struct dwc3_ep                  *dep;
        u8                              epnum;

        for (epnum = 0; epnum < DWC3_ENDPOINTS_NUM; epnum++) {
                dep = dwc->eps[epnum];
                if (!dep)
                        continue;
                /*
                 * Physical endpoints 0 and 1 are special; they form the
                 * bi-directional USB endpoint 0.
                 *
                 * For those two physical endpoints, we don't allocate a TRB
                 * pool nor do we add them the endpoints list. Due to that, we
                 * shouldn't do these two operations otherwise we would end up
                 * with all sorts of bugs when removing dwc3.ko.
                 */
                if (epnum != 0 && epnum != 1) {
                        dwc3_free_trb_pool(dep);
                        list_del(&dep->endpoint.ep_list);
                }

                kfree(dep);
        }
}

/* -------------------------------------------------------------------------- */

static int dwc3_gadget_ep_reclaim_completed_trb(struct dwc3_ep *dep,
                struct dwc3_request *req, struct dwc3_trb *trb,
                const struct dwc3_event_depevt *event, int status, int chain)
{
        unsigned int            count;

        dwc3_ep_inc_deq(dep);

        trace_dwc3_complete_trb(dep, trb);
        req->num_trbs--;

        /*
         * If we're in the middle of series of chained TRBs and we
         * receive a short transfer along the way, DWC3 will skip
         * through all TRBs including the last TRB in the chain (the
         * where CHN bit is zero. DWC3 will also avoid clearing HWO
         * bit and SW has to do it manually.
         *
         * We're going to do that here to avoid problems of HW trying
         * to use bogus TRBs for transfers.
         */
        if (chain && (trb->ctrl & DWC3_TRB_CTRL_HWO))
                trb->ctrl &= ~DWC3_TRB_CTRL_HWO;

        /*
         * For isochronous transfers, the first TRB in a service interval must
         * have the Isoc-First type. Track and report its interval frame number.
         */
        if (usb_endpoint_xfer_isoc(dep->endpoint.desc) &&
            (trb->ctrl & DWC3_TRBCTL_ISOCHRONOUS_FIRST)) {
                unsigned int frame_number;

                frame_number = DWC3_TRB_CTRL_GET_SID_SOFN(trb->ctrl);
                frame_number &= ~(dep->interval - 1);
                req->request.frame_number = frame_number;
        }

        /*
         * We use bounce buffer for requests that needs extra TRB or OUT ZLP. If
         * this TRB points to the bounce buffer address, it's a MPS alignment
         * TRB. Don't add it to req->remaining calculation.
         */
        if (trb->bpl == lower_32_bits(dep->dwc->bounce_addr) &&
            trb->bph == upper_32_bits(dep->dwc->bounce_addr)) {
                trb->ctrl &= ~DWC3_TRB_CTRL_HWO;
                return 1;
        }

        count = trb->size & DWC3_TRB_SIZE_MASK;
        req->remaining += count;

        if ((trb->ctrl & DWC3_TRB_CTRL_HWO) && status != -ESHUTDOWN)
                return 1;

        if (event->status & DEPEVT_STATUS_SHORT && !chain)
                return 1;

        if ((trb->ctrl & DWC3_TRB_CTRL_IOC) ||
            (trb->ctrl & DWC3_TRB_CTRL_LST))
                return 1;

        return 0;
}

static int dwc3_gadget_ep_reclaim_trb_sg(struct dwc3_ep *dep,
                struct dwc3_request *req, const struct dwc3_event_depevt *event,
                int status)
{
        struct dwc3_trb *trb = &dep->trb_pool[dep->trb_dequeue];
        struct scatterlist *sg = req->sg;
        struct scatterlist *s;
        unsigned int pending = req->num_pending_sgs;
        unsigned int i;
        int ret = 0;

        for_each_sg(sg, s, pending, i) {
                trb = &dep->trb_pool[dep->trb_dequeue];

                req->sg = sg_next(s);
                req->num_pending_sgs--;

                ret = dwc3_gadget_ep_reclaim_completed_trb(dep, req,
                                trb, event, status, true);
                if (ret)
                        break;
        }

        return ret;
}

static int dwc3_gadget_ep_reclaim_trb_linear(struct dwc3_ep *dep,
                struct dwc3_request *req, const struct dwc3_event_depevt *event,
                int status)
{
        struct dwc3_trb *trb = &dep->trb_pool[dep->trb_dequeue];

        return dwc3_gadget_ep_reclaim_completed_trb(dep, req, trb,
                        event, status, false);
}

static bool dwc3_gadget_ep_request_completed(struct dwc3_request *req)
{
        return req->num_pending_sgs == 0;
}

static int dwc3_gadget_ep_cleanup_completed_request(struct dwc3_ep *dep,
                const struct dwc3_event_depevt *event,
                struct dwc3_request *req, int status)
{
        int ret;

        if (req->num_pending_sgs)
                ret = dwc3_gadget_ep_reclaim_trb_sg(dep, req, event,
                                status);
        else
                ret = dwc3_gadget_ep_reclaim_trb_linear(dep, req, event,
                                status);

        req->request.actual = req->request.length - req->remaining;

        if (!dwc3_gadget_ep_request_completed(req))
                goto out;

        if (req->needs_extra_trb) {
                ret = dwc3_gadget_ep_reclaim_trb_linear(dep, req, event,
                                status);
                req->needs_extra_trb = false;
        }

        dwc3_gadget_giveback(dep, req, status);

out:
        return ret;
}

static void dwc3_gadget_ep_cleanup_completed_requests(struct dwc3_ep *dep,
                const struct dwc3_event_depevt *event, int status)
{
        struct dwc3_request     *req;
        struct dwc3_request     *tmp;

        list_for_each_entry_safe(req, tmp, &dep->started_list, list) {
                int ret;

                ret = dwc3_gadget_ep_cleanup_completed_request(dep, event,
                                req, status);
                if (ret)
                        break;
        }
}

static bool dwc3_gadget_ep_should_continue(struct dwc3_ep *dep)
{
        struct dwc3_request     *req;

        if (!list_empty(&dep->pending_list))
                return true;

        /*
         * We only need to check the first entry of the started list. We can
         * assume the completed requests are removed from the started list.
         */
        req = next_request(&dep->started_list);
        if (!req)
                return false;

        return !dwc3_gadget_ep_request_completed(req);
}

static void dwc3_gadget_endpoint_frame_from_event(struct dwc3_ep *dep,
                const struct dwc3_event_depevt *event)
{
        dep->frame_number = event->parameters;
}

static bool dwc3_gadget_endpoint_trbs_complete(struct dwc3_ep *dep,
                const struct dwc3_event_depevt *event, int status)
{
        struct dwc3             *dwc = dep->dwc;
        bool                    no_started_trb = true;

        dwc3_gadget_ep_cleanup_completed_requests(dep, event, status);

        if (dep->flags & DWC3_EP_END_TRANSFER_PENDING)
                goto out;

        if (usb_endpoint_xfer_isoc(dep->endpoint.desc) &&
                list_empty(&dep->started_list) &&
                (list_empty(&dep->pending_list) || status == -EXDEV))
                dwc3_stop_active_transfer(dep, true, true);
        else if (dwc3_gadget_ep_should_continue(dep))
                if (__dwc3_gadget_kick_transfer(dep) == 0)
                        no_started_trb = false;

out:
        /*
         * WORKAROUND: This is the 2nd half of U1/U2 -> U0 workaround.
         * See dwc3_gadget_linksts_change_interrupt() for 1st half.
         */
        if (DWC3_VER_IS_PRIOR(DWC3, 183A)) {
                u32             reg;
                int             i;

                for (i = 0; i < DWC3_ENDPOINTS_NUM; i++) {
                        dep = dwc->eps[i];

                        if (!(dep->flags & DWC3_EP_ENABLED))
                                continue;

                        if (!list_empty(&dep->started_list))
                                return no_started_trb;
                }

                reg = dwc3_readl(dwc->regs, DWC3_DCTL);
                reg |= dwc->u1u2;
                dwc3_writel(dwc->regs, DWC3_DCTL, reg);

                dwc->u1u2 = 0;
        }

        return no_started_trb;
}

static void dwc3_gadget_endpoint_transfer_in_progress(struct dwc3_ep *dep,
                const struct dwc3_event_depevt *event)
{
        int status = 0;

        if (usb_endpoint_xfer_isoc(dep->endpoint.desc))
                dwc3_gadget_endpoint_frame_from_event(dep, event);

        if (event->status & DEPEVT_STATUS_BUSERR)
                status = -ECONNRESET;

        if (event->status & DEPEVT_STATUS_MISSED_ISOC)
                status = -EXDEV;

        dwc3_gadget_endpoint_trbs_complete(dep, event, status);
}

static void dwc3_gadget_endpoint_transfer_complete(struct dwc3_ep *dep,
                const struct dwc3_event_depevt *event)
{
        int status = 0;

        dep->flags &= ~DWC3_EP_TRANSFER_STARTED;

        if (event->status & DEPEVT_STATUS_BUSERR)
                status = -ECONNRESET;

        if (dwc3_gadget_endpoint_trbs_complete(dep, event, status))
                dep->flags &= ~DWC3_EP_WAIT_TRANSFER_COMPLETE;
}

static void dwc3_gadget_endpoint_transfer_not_ready(struct dwc3_ep *dep,
                const struct dwc3_event_depevt *event)
{
        dwc3_gadget_endpoint_frame_from_event(dep, event);

        /*
         * The XferNotReady event is generated only once before the endpoint
         * starts. It will be generated again when END_TRANSFER command is
         * issued. For some controller versions, the XferNotReady event may be
         * generated while the END_TRANSFER command is still in process. Ignore
         * it and wait for the next XferNotReady event after the command is
         * completed.
         */
        if (dep->flags & DWC3_EP_END_TRANSFER_PENDING)
                return;

        (void) __dwc3_gadget_start_isoc(dep);
}

static void dwc3_gadget_endpoint_command_complete(struct dwc3_ep *dep,
                const struct dwc3_event_depevt *event)
{
        u8 cmd = DEPEVT_PARAMETER_CMD(event->parameters);

        if (cmd != DWC3_DEPCMD_ENDTRANSFER)
                return;

        dep->flags &= ~DWC3_EP_END_TRANSFER_PENDING;
        dep->flags &= ~DWC3_EP_TRANSFER_STARTED;
        dwc3_gadget_ep_cleanup_cancelled_requests(dep);

        if (dep->flags & DWC3_EP_PENDING_CLEAR_STALL) {
                struct dwc3 *dwc = dep->dwc;

                dep->flags &= ~DWC3_EP_PENDING_CLEAR_STALL;
                if (dwc3_send_clear_stall_ep_cmd(dep)) {
                        struct usb_ep *ep0 = &dwc->eps[0]->endpoint;

                        dev_err(dwc->dev, "failed to clear STALL on %s\n", dep->name);
                        if (dwc->delayed_status)
                                __dwc3_gadget_ep0_set_halt(ep0, 1);
                        return;
                }

                dep->flags &= ~(DWC3_EP_STALL | DWC3_EP_WEDGE);
                if (dwc->delayed_status)
                        dwc3_ep0_send_delayed_status(dwc);
        }

        if ((dep->flags & DWC3_EP_DELAY_START) &&
            !usb_endpoint_xfer_isoc(dep->endpoint.desc))
                __dwc3_gadget_kick_transfer(dep);

        dep->flags &= ~DWC3_EP_DELAY_START;
}

static void dwc3_gadget_endpoint_stream_event(struct dwc3_ep *dep,
                const struct dwc3_event_depevt *event)
{
        struct dwc3 *dwc = dep->dwc;

        if (event->status == DEPEVT_STREAMEVT_FOUND) {
                dep->flags |= DWC3_EP_FIRST_STREAM_PRIMED;
                goto out;
        }

        /* Note: NoStream rejection event param value is 0 and not 0xFFFF */
        switch (event->parameters) {
        case DEPEVT_STREAM_PRIME:
                /*
                 * If the host can properly transition the endpoint state from
                 * idle to prime after a NoStream rejection, there's no need to
                 * force restarting the endpoint to reinitiate the stream. To
                 * simplify the check, assume the host follows the USB spec if
                 * it primed the endpoint more than once.
                 */
                if (dep->flags & DWC3_EP_FORCE_RESTART_STREAM) {
                        if (dep->flags & DWC3_EP_FIRST_STREAM_PRIMED)
                                dep->flags &= ~DWC3_EP_FORCE_RESTART_STREAM;
                        else
                                dep->flags |= DWC3_EP_FIRST_STREAM_PRIMED;
                }

                break;
        case DEPEVT_STREAM_NOSTREAM:
                if ((dep->flags & DWC3_EP_IGNORE_NEXT_NOSTREAM) ||
                    !(dep->flags & DWC3_EP_FORCE_RESTART_STREAM) ||
                    !(dep->flags & DWC3_EP_WAIT_TRANSFER_COMPLETE))
                        break;

                /*
                 * If the host rejects a stream due to no active stream, by the
                 * USB and xHCI spec, the endpoint will be put back to idle
                 * state. When the host is ready (buffer added/updated), it will
                 * prime the endpoint to inform the usb device controller. This
                 * triggers the device controller to issue ERDY to restart the
                 * stream. However, some hosts don't follow this and keep the
                 * endpoint in the idle state. No prime will come despite host
                 * streams are updated, and the device controller will not be
                 * triggered to generate ERDY to move the next stream data. To
                 * workaround this and maintain compatibility with various
                 * hosts, force to reinitate the stream until the host is ready
                 * instead of waiting for the host to prime the endpoint.
                 */
                if (DWC3_VER_IS_WITHIN(DWC32, 100A, ANY)) {
                        unsigned int cmd = DWC3_DGCMD_SET_ENDPOINT_PRIME;

                        dwc3_send_gadget_generic_command(dwc, cmd, dep->number);
                } else {
                        dep->flags |= DWC3_EP_DELAY_START;
                        dwc3_stop_active_transfer(dep, true, true);
                        return;
                }
                break;
        }

out:
        dep->flags &= ~DWC3_EP_IGNORE_NEXT_NOSTREAM;
}

static void dwc3_endpoint_interrupt(struct dwc3 *dwc,
                const struct dwc3_event_depevt *event)
{
        struct dwc3_ep          *dep;
        u8                      epnum = event->endpoint_number;

        dep = dwc->eps[epnum];

        if (!(dep->flags & DWC3_EP_ENABLED)) {
                if (!(dep->flags & DWC3_EP_TRANSFER_STARTED))
                        return;

                /* Handle only EPCMDCMPLT when EP disabled */
                if (event->endpoint_event != DWC3_DEPEVT_EPCMDCMPLT)
                        return;
        }

        if (epnum == 0 || epnum == 1) {
                dwc3_ep0_interrupt(dwc, event);
                return;
        }

        switch (event->endpoint_event) {
        case DWC3_DEPEVT_XFERINPROGRESS:
                dwc3_gadget_endpoint_transfer_in_progress(dep, event);
                break;
        case DWC3_DEPEVT_XFERNOTREADY:
                dwc3_gadget_endpoint_transfer_not_ready(dep, event);
                break;
        case DWC3_DEPEVT_EPCMDCMPLT:
                dwc3_gadget_endpoint_command_complete(dep, event);
                break;
        case DWC3_DEPEVT_XFERCOMPLETE:
                dwc3_gadget_endpoint_transfer_complete(dep, event);
                break;
        case DWC3_DEPEVT_STREAMEVT:
                dwc3_gadget_endpoint_stream_event(dep, event);
                break;
        case DWC3_DEPEVT_RXTXFIFOEVT:
                break;
        }
}

static void dwc3_disconnect_gadget(struct dwc3 *dwc)
{
        if (dwc->gadget_driver && dwc->gadget_driver->disconnect) {
                spin_unlock(&dwc->lock);
                dwc->gadget_driver->disconnect(dwc->gadget);
                spin_lock(&dwc->lock);
        }
}

static void dwc3_suspend_gadget(struct dwc3 *dwc)
{
        if (dwc->gadget_driver && dwc->gadget_driver->suspend) {
                spin_unlock(&dwc->lock);
                dwc->gadget_driver->suspend(dwc->gadget);
                spin_lock(&dwc->lock);
        }
}

static void dwc3_resume_gadget(struct dwc3 *dwc)
{
        if (dwc->gadget_driver && dwc->gadget_driver->resume) {
                spin_unlock(&dwc->lock);
                dwc->gadget_driver->resume(dwc->gadget);
                spin_lock(&dwc->lock);
        }
}

static void dwc3_reset_gadget(struct dwc3 *dwc)
{
        if (!dwc->gadget_driver)
                return;

        if (dwc->gadget->speed != USB_SPEED_UNKNOWN) {
                spin_unlock(&dwc->lock);
                usb_gadget_udc_reset(dwc->gadget, dwc->gadget_driver);
                spin_lock(&dwc->lock);
        }
}

static void dwc3_stop_active_transfer(struct dwc3_ep *dep, bool force,
        bool interrupt)
{
        struct dwc3_gadget_ep_cmd_params params;
        u32 cmd;
        int ret;

        if (!(dep->flags & DWC3_EP_TRANSFER_STARTED) ||
            (dep->flags & DWC3_EP_END_TRANSFER_PENDING))
                return;

        /*
         * NOTICE: We are violating what the Databook says about the
         * EndTransfer command. Ideally we would _always_ wait for the
         * EndTransfer Command Completion IRQ, but that's causing too
         * much trouble synchronizing between us and gadget driver.
         *
         * We have discussed this with the IP Provider and it was
         * suggested to giveback all requests here.
         *
         * Note also that a similar handling was tested by Synopsys
         * (thanks a lot Paul) and nothing bad has come out of it.
         * In short, what we're doing is issuing EndTransfer with
         * CMDIOC bit set and delay kicking transfer until the
         * EndTransfer command had completed.
         *
         * As of IP version 3.10a of the DWC_usb3 IP, the controller
         * supports a mode to work around the above limitation. The
         * software can poll the CMDACT bit in the DEPCMD register
         * after issuing a EndTransfer command. This mode is enabled
         * by writing GUCTL2[14]. This polling is already done in the
         * dwc3_send_gadget_ep_cmd() function so if the mode is
         * enabled, the EndTransfer command will have completed upon
         * returning from this function.
         *
         * This mode is NOT available on the DWC_usb31 IP.
         */

        cmd = DWC3_DEPCMD_ENDTRANSFER;
        cmd |= force ? DWC3_DEPCMD_HIPRI_FORCERM : 0;
        cmd |= interrupt ? DWC3_DEPCMD_CMDIOC : 0;
        cmd |= DWC3_DEPCMD_PARAM(dep->resource_index);
        memset(&params, 0, sizeof(params));
        ret = dwc3_send_gadget_ep_cmd(dep, cmd, &params);
        WARN_ON_ONCE(ret);
        dep->resource_index = 0;

        /*
         * The END_TRANSFER command will cause the controller to generate a
         * NoStream Event, and it's not due to the host DP NoStream rejection.
         * Ignore the next NoStream event.
         */
        if (dep->stream_capable)
                dep->flags |= DWC3_EP_IGNORE_NEXT_NOSTREAM;

        if (!interrupt)
                dep->flags &= ~DWC3_EP_TRANSFER_STARTED;
        else
                dep->flags |= DWC3_EP_END_TRANSFER_PENDING;
}

static void dwc3_clear_stall_all_ep(struct dwc3 *dwc)
{
        u32 epnum;

        for (epnum = 1; epnum < DWC3_ENDPOINTS_NUM; epnum++) {
                struct dwc3_ep *dep;
                int ret;

                dep = dwc->eps[epnum];
                if (!dep)
                        continue;

                if (!(dep->flags & DWC3_EP_STALL))
                        continue;

                dep->flags &= ~DWC3_EP_STALL;

                ret = dwc3_send_clear_stall_ep_cmd(dep);
                WARN_ON_ONCE(ret);
        }
}

static void dwc3_gadget_disconnect_interrupt(struct dwc3 *dwc)
{
        int                     reg;

        dwc3_gadget_set_link_state(dwc, DWC3_LINK_STATE_RX_DET);

        reg = dwc3_readl(dwc->regs, DWC3_DCTL);
        reg &= ~DWC3_DCTL_INITU1ENA;
        reg &= ~DWC3_DCTL_INITU2ENA;
        dwc3_gadget_dctl_write_safe(dwc, reg);

        dwc3_disconnect_gadget(dwc);

        dwc->gadget->speed = USB_SPEED_UNKNOWN;
        dwc->setup_packet_pending = false;
        usb_gadget_set_state(dwc->gadget, USB_STATE_NOTATTACHED);

        dwc->connected = false;
}

static void dwc3_gadget_reset_interrupt(struct dwc3 *dwc)
{
        u32                     reg;

        dwc->connected = true;

        /*
         * WORKAROUND: DWC3 revisions <1.88a have an issue which
         * would cause a missing Disconnect Event if there's a
         * pending Setup Packet in the FIFO.
         *
         * There's no suggested workaround on the official Bug
         * report, which states that "unless the driver/application
         * is doing any special handling of a disconnect event,
         * there is no functional issue".
         *
         * Unfortunately, it turns out that we _do_ some special
         * handling of a disconnect event, namely complete all
         * pending transfers, notify gadget driver of the
         * disconnection, and so on.
         *
         * Our suggested workaround is to follow the Disconnect
         * Event steps here, instead, based on a setup_packet_pending
         * flag. Such flag gets set whenever we have a SETUP_PENDING
         * status for EP0 TRBs and gets cleared on XferComplete for the
         * same endpoint.
         *
         * Refers to:
         *
         * STAR#9000466709: RTL: Device : Disconnect event not
         * generated if setup packet pending in FIFO
         */
        if (DWC3_VER_IS_PRIOR(DWC3, 188A)) {
                if (dwc->setup_packet_pending)
                        dwc3_gadget_disconnect_interrupt(dwc);
        }

        dwc3_reset_gadget(dwc);
        /*
         * In the Synopsis DesignWare Cores USB3 Databook Rev. 3.30a
         * Section 4.1.2 Table 4-2, it states that during a USB reset, the SW
         * needs to ensure that it sends "a DEPENDXFER command for any active
         * transfers."
         */
        dwc3_stop_active_transfers(dwc);

        reg = dwc3_readl(dwc->regs, DWC3_DCTL);
        reg &= ~DWC3_DCTL_TSTCTRL_MASK;
        dwc3_gadget_dctl_write_safe(dwc, reg);
        dwc->test_mode = false;
        dwc3_clear_stall_all_ep(dwc);

        /* Reset device address to zero */
        reg = dwc3_readl(dwc->regs, DWC3_DCFG);
        reg &= ~(DWC3_DCFG_DEVADDR_MASK);
        dwc3_writel(dwc->regs, DWC3_DCFG, reg);
}

static void dwc3_gadget_conndone_interrupt(struct dwc3 *dwc)
{
        struct dwc3_ep          *dep;
        int                     ret;
        u32                     reg;
        u8                      speed;

        reg = dwc3_readl(dwc->regs, DWC3_DSTS);
        speed = reg & DWC3_DSTS_CONNECTSPD;
        dwc->speed = speed;

        /*
         * RAMClkSel is reset to 0 after USB reset, so it must be reprogrammed
         * each time on Connect Done.
         *
         * Currently we always use the reset value. If any platform
         * wants to set this to a different value, we need to add a
         * setting and update GCTL.RAMCLKSEL here.
         */

        switch (speed) {
        case DWC3_DSTS_SUPERSPEED_PLUS:
                dwc3_gadget_ep0_desc.wMaxPacketSize = cpu_to_le16(512);
                dwc->gadget->ep0->maxpacket = 512;
                dwc->gadget->speed = USB_SPEED_SUPER_PLUS;
                break;
        case DWC3_DSTS_SUPERSPEED:
                /*
                 * WORKAROUND: DWC3 revisions <1.90a have an issue which
                 * would cause a missing USB3 Reset event.
                 *
                 * In such situations, we should force a USB3 Reset
                 * event by calling our dwc3_gadget_reset_interrupt()
                 * routine.
                 *
                 * Refers to:
                 *
                 * STAR#9000483510: RTL: SS : USB3 reset event may
                 * not be generated always when the link enters poll
                 */
                if (DWC3_VER_IS_PRIOR(DWC3, 190A))
                        dwc3_gadget_reset_interrupt(dwc);

                dwc3_gadget_ep0_desc.wMaxPacketSize = cpu_to_le16(512);
                dwc->gadget->ep0->maxpacket = 512;
                dwc->gadget->speed = USB_SPEED_SUPER;
                break;
        case DWC3_DSTS_HIGHSPEED:
                dwc3_gadget_ep0_desc.wMaxPacketSize = cpu_to_le16(64);
                dwc->gadget->ep0->maxpacket = 64;
                dwc->gadget->speed = USB_SPEED_HIGH;
                break;
        case DWC3_DSTS_FULLSPEED:
                dwc3_gadget_ep0_desc.wMaxPacketSize = cpu_to_le16(64);
                dwc->gadget->ep0->maxpacket = 64;
                dwc->gadget->speed = USB_SPEED_FULL;
                break;
        case DWC3_DSTS_LOWSPEED:
                dwc3_gadget_ep0_desc.wMaxPacketSize = cpu_to_le16(8);
                dwc->gadget->ep0->maxpacket = 8;
                dwc->gadget->speed = USB_SPEED_LOW;
                break;
        }

        dwc->eps[1]->endpoint.maxpacket = dwc->gadget->ep0->maxpacket;

        /* Enable USB2 LPM Capability */

        if (!DWC3_VER_IS_WITHIN(DWC3, ANY, 194A) &&
            (speed != DWC3_DSTS_SUPERSPEED) &&
            (speed != DWC3_DSTS_SUPERSPEED_PLUS)) {
                reg = dwc3_readl(dwc->regs, DWC3_DCFG);
                reg |= DWC3_DCFG_LPM_CAP;
                dwc3_writel(dwc->regs, DWC3_DCFG, reg);

                reg = dwc3_readl(dwc->regs, DWC3_DCTL);
                reg &= ~(DWC3_DCTL_HIRD_THRES_MASK | DWC3_DCTL_L1_HIBER_EN);

                reg |= DWC3_DCTL_HIRD_THRES(dwc->hird_threshold |
                                            (dwc->is_utmi_l1_suspend << 4));

                /*
                 * When dwc3 revisions >= 2.40a, LPM Erratum is enabled and
                 * DCFG.LPMCap is set, core responses with an ACK and the
                 * BESL value in the LPM token is less than or equal to LPM
                 * NYET threshold.
                 */
                WARN_ONCE(DWC3_VER_IS_PRIOR(DWC3, 240A) && dwc->has_lpm_erratum,
                                "LPM Erratum not available on dwc3 revisions < 2.40a\n");

                if (dwc->has_lpm_erratum && !DWC3_VER_IS_PRIOR(DWC3, 240A))
                        reg |= DWC3_DCTL_NYET_THRES(dwc->lpm_nyet_threshold);

                dwc3_gadget_dctl_write_safe(dwc, reg);
        } else {
                reg = dwc3_readl(dwc->regs, DWC3_DCTL);
                reg &= ~DWC3_DCTL_HIRD_THRES_MASK;
                dwc3_gadget_dctl_write_safe(dwc, reg);
        }

        dep = dwc->eps[0];
        ret = __dwc3_gadget_ep_enable(dep, DWC3_DEPCFG_ACTION_MODIFY);
        if (ret) {
                dev_err(dwc->dev, "failed to enable %s\n", dep->name);
                return;
        }

        dep = dwc->eps[1];
        ret = __dwc3_gadget_ep_enable(dep, DWC3_DEPCFG_ACTION_MODIFY);
        if (ret) {
                dev_err(dwc->dev, "failed to enable %s\n", dep->name);
                return;
        }

        /*
         * Configure PHY via GUSB3PIPECTLn if required.
         *
         * Update GTXFIFOSIZn
         *
         * In both cases reset values should be sufficient.
         */
}

static void dwc3_gadget_wakeup_interrupt(struct dwc3 *dwc)
{
        /*
         * TODO take core out of low power mode when that's
         * implemented.
         */

        if (dwc->gadget_driver && dwc->gadget_driver->resume) {
                spin_unlock(&dwc->lock);
                dwc->gadget_driver->resume(dwc->gadget);
                spin_lock(&dwc->lock);
        }
}

static void dwc3_gadget_linksts_change_interrupt(struct dwc3 *dwc,
                unsigned int evtinfo)
{
        enum dwc3_link_state    next = evtinfo & DWC3_LINK_STATE_MASK;
        unsigned int            pwropt;

        /*
         * WORKAROUND: DWC3 < 2.50a have an issue when configured without
         * Hibernation mode enabled which would show up when device detects
         * host-initiated U3 exit.
         *
         * In that case, device will generate a Link State Change Interrupt
         * from U3 to RESUME which is only necessary if Hibernation is
         * configured in.
         *
         * There are no functional changes due to such spurious event and we
         * just need to ignore it.
         *
         * Refers to:
         *
         * STAR#9000570034 RTL: SS Resume event generated in non-Hibernation
         * operational mode
         */
        pwropt = DWC3_GHWPARAMS1_EN_PWROPT(dwc->hwparams.hwparams1);
        if (DWC3_VER_IS_PRIOR(DWC3, 250A) &&
                        (pwropt != DWC3_GHWPARAMS1_EN_PWROPT_HIB)) {
                if ((dwc->link_state == DWC3_LINK_STATE_U3) &&
                                (next == DWC3_LINK_STATE_RESUME)) {
                        return;
                }
        }

        /*
         * WORKAROUND: DWC3 Revisions <1.83a have an issue which, depending
         * on the link partner, the USB session might do multiple entry/exit
         * of low power states before a transfer takes place.
         *
         * Due to this problem, we might experience lower throughput. The
         * suggested workaround is to disable DCTL[12:9] bits if we're
         * transitioning from U1/U2 to U0 and enable those bits again
         * after a transfer completes and there are no pending transfers
         * on any of the enabled endpoints.
         *
         * This is the first half of that workaround.
         *
         * Refers to:
         *
         * STAR#9000446952: RTL: Device SS : if U1/U2 ->U0 takes >128us
         * core send LGO_Ux entering U0
         */
        if (DWC3_VER_IS_PRIOR(DWC3, 183A)) {
                if (next == DWC3_LINK_STATE_U0) {
                        u32     u1u2;
                        u32     reg;

                        switch (dwc->link_state) {
                        case DWC3_LINK_STATE_U1:
                        case DWC3_LINK_STATE_U2:
                                reg = dwc3_readl(dwc->regs, DWC3_DCTL);
                                u1u2 = reg & (DWC3_DCTL_INITU2ENA
                                                | DWC3_DCTL_ACCEPTU2ENA
                                                | DWC3_DCTL_INITU1ENA
                                                | DWC3_DCTL_ACCEPTU1ENA);

                                if (!dwc->u1u2)
                                        dwc->u1u2 = reg & u1u2;

                                reg &= ~u1u2;

                                dwc3_gadget_dctl_write_safe(dwc, reg);
                                break;
                        default:
                                /* do nothing */
                                break;
                        }
                }
        }

        switch (next) {
        case DWC3_LINK_STATE_U1:
                if (dwc->speed == USB_SPEED_SUPER)
                        dwc3_suspend_gadget(dwc);
                break;
        case DWC3_LINK_STATE_U2:
        case DWC3_LINK_STATE_U3:
                dwc3_suspend_gadget(dwc);
                break;
        case DWC3_LINK_STATE_RESUME:
                dwc3_resume_gadget(dwc);
                break;
        default:
                /* do nothing */
                break;
        }

        dwc->link_state = next;
}

static void dwc3_gadget_suspend_interrupt(struct dwc3 *dwc,
                                          unsigned int evtinfo)
{
        enum dwc3_link_state next = evtinfo & DWC3_LINK_STATE_MASK;

        if (dwc->link_state != next && next == DWC3_LINK_STATE_U3)
                dwc3_suspend_gadget(dwc);

        dwc->link_state = next;
}

static void dwc3_gadget_hibernation_interrupt(struct dwc3 *dwc,
                unsigned int evtinfo)
{
        unsigned int is_ss = evtinfo & BIT(4);

        /*
         * WORKAROUND: DWC3 revison 2.20a with hibernation support
         * have a known issue which can cause USB CV TD.9.23 to fail
         * randomly.
         *
         * Because of this issue, core could generate bogus hibernation
         * events which SW needs to ignore.
         *
         * Refers to:
         *
         * STAR#9000546576: Device Mode Hibernation: Issue in USB 2.0
         * Device Fallback from SuperSpeed
         */
        if (is_ss ^ (dwc->speed == USB_SPEED_SUPER))
                return;

        /* enter hibernation here */
}

static void dwc3_gadget_interrupt(struct dwc3 *dwc,
                const struct dwc3_event_devt *event)
{
        switch (event->type) {
        case DWC3_DEVICE_EVENT_DISCONNECT:
                dwc3_gadget_disconnect_interrupt(dwc);
                break;
        case DWC3_DEVICE_EVENT_RESET:
                dwc3_gadget_reset_interrupt(dwc);
                break;
        case DWC3_DEVICE_EVENT_CONNECT_DONE:
                dwc3_gadget_conndone_interrupt(dwc);
                break;
        case DWC3_DEVICE_EVENT_WAKEUP:
                dwc3_gadget_wakeup_interrupt(dwc);
                break;
        case DWC3_DEVICE_EVENT_HIBER_REQ:
                if (dev_WARN_ONCE(dwc->dev, !dwc->has_hibernation,
                                        "unexpected hibernation event\n"))
                        break;

                dwc3_gadget_hibernation_interrupt(dwc, event->event_info);
                break;
        case DWC3_DEVICE_EVENT_LINK_STATUS_CHANGE:
                dwc3_gadget_linksts_change_interrupt(dwc, event->event_info);
                break;
        case DWC3_DEVICE_EVENT_EOPF:
                /* It changed to be suspend event for version 2.30a and above */
                if (!DWC3_VER_IS_PRIOR(DWC3, 230A)) {
                        /*
                         * Ignore suspend event until the gadget enters into
                         * USB_STATE_CONFIGURED state.
                         */
                        if (dwc->gadget->state >= USB_STATE_CONFIGURED)
                                dwc3_gadget_suspend_interrupt(dwc,
                                                event->event_info);
                }
                break;
        case DWC3_DEVICE_EVENT_SOF:
        case DWC3_DEVICE_EVENT_ERRATIC_ERROR:
        case DWC3_DEVICE_EVENT_CMD_CMPL:
        case DWC3_DEVICE_EVENT_OVERFLOW:
                break;
        default:
                dev_WARN(dwc->dev, "UNKNOWN IRQ %d\n", event->type);
        }
}

static void dwc3_process_event_entry(struct dwc3 *dwc,
                const union dwc3_event *event)
{
        trace_dwc3_event(event->raw, dwc);

        if (!event->type.is_devspec)
                dwc3_endpoint_interrupt(dwc, &event->depevt);
        else if (event->type.type == DWC3_EVENT_TYPE_DEV)
                dwc3_gadget_interrupt(dwc, &event->devt);
        else
                dev_err(dwc->dev, "UNKNOWN IRQ type %d\n", event->raw);
}

static irqreturn_t dwc3_process_event_buf(struct dwc3_event_buffer *evt)
{
        struct dwc3 *dwc = evt->dwc;
        irqreturn_t ret = IRQ_NONE;
        int left;
        u32 reg;

        left = evt->count;

        if (!(evt->flags & DWC3_EVENT_PENDING))
                return IRQ_NONE;

        while (left > 0) {
                union dwc3_event event;

                event.raw = *(u32 *) (evt->cache + evt->lpos);

                dwc3_process_event_entry(dwc, &event);

                /*
                 * FIXME we wrap around correctly to the next entry as
                 * almost all entries are 4 bytes in size. There is one
                 * entry which has 12 bytes which is a regular entry
                 * followed by 8 bytes data. ATM I don't know how
                 * things are organized if we get next to the a
                 * boundary so I worry about that once we try to handle
                 * that.
                 */
                evt->lpos = (evt->lpos + 4) % evt->length;
                left -= 4;
        }

        evt->count = 0;
        evt->flags &= ~DWC3_EVENT_PENDING;
        ret = IRQ_HANDLED;

        /* Unmask interrupt */
        reg = dwc3_readl(dwc->regs, DWC3_GEVNTSIZ(0));
        reg &= ~DWC3_GEVNTSIZ_INTMASK;
        dwc3_writel(dwc->regs, DWC3_GEVNTSIZ(0), reg);

        if (dwc->imod_interval) {
                dwc3_writel(dwc->regs, DWC3_GEVNTCOUNT(0), DWC3_GEVNTCOUNT_EHB);
                dwc3_writel(dwc->regs, DWC3_DEV_IMOD(0), dwc->imod_interval);
        }

        return ret;
}

static irqreturn_t dwc3_thread_interrupt(int irq, void *_evt)
{
        struct dwc3_event_buffer *evt = _evt;
        struct dwc3 *dwc = evt->dwc;
        unsigned long flags;
        irqreturn_t ret = IRQ_NONE;

        spin_lock_irqsave(&dwc->lock, flags);
        ret = dwc3_process_event_buf(evt);
        spin_unlock_irqrestore(&dwc->lock, flags);

        return ret;
}

static irqreturn_t dwc3_check_event_buf(struct dwc3_event_buffer *evt)
{
        struct dwc3 *dwc = evt->dwc;
        u32 amount;
        u32 count;
        u32 reg;

        if (pm_runtime_suspended(dwc->dev)) {
                pm_runtime_get(dwc->dev);
                disable_irq_nosync(dwc->irq_gadget);
                dwc->pending_events = true;
                return IRQ_HANDLED;
        }

        /*
         * With PCIe legacy interrupt, test shows that top-half irq handler can
         * be called again after HW interrupt deassertion. Check if bottom-half
         * irq event handler completes before caching new event to prevent
         * losing events.
         */
        if (evt->flags & DWC3_EVENT_PENDING)
                return IRQ_HANDLED;

        count = dwc3_readl(dwc->regs, DWC3_GEVNTCOUNT(0));
        count &= DWC3_GEVNTCOUNT_MASK;
        if (!count)
                return IRQ_NONE;

        evt->count = count;
        evt->flags |= DWC3_EVENT_PENDING;

        /* Mask interrupt */
        reg = dwc3_readl(dwc->regs, DWC3_GEVNTSIZ(0));
        reg |= DWC3_GEVNTSIZ_INTMASK;
        dwc3_writel(dwc->regs, DWC3_GEVNTSIZ(0), reg);

        amount = min(count, evt->length - evt->lpos);
        memcpy(evt->cache + evt->lpos, evt->buf + evt->lpos, amount);

        if (amount < count)
                memcpy(evt->cache, evt->buf, count - amount);

        dwc3_writel(dwc->regs, DWC3_GEVNTCOUNT(0), count);

        return IRQ_WAKE_THREAD;
}

static irqreturn_t dwc3_interrupt(int irq, void *_evt)
{
        struct dwc3_event_buffer        *evt = _evt;

        return dwc3_check_event_buf(evt);
}

static int dwc3_gadget_get_irq(struct dwc3 *dwc)
{
        struct platform_device *dwc3_pdev = to_platform_device(dwc->dev);
        int irq;

        irq = platform_get_irq_byname_optional(dwc3_pdev, "peripheral");
        if (irq > 0)
                goto out;

        if (irq == -EPROBE_DEFER)
                goto out;

        irq = platform_get_irq_byname_optional(dwc3_pdev, "dwc_usb3");
        if (irq > 0)
                goto out;

        if (irq == -EPROBE_DEFER)
                goto out;

        irq = platform_get_irq(dwc3_pdev, 0);
        if (irq > 0)
                goto out;

        if (!irq)
                irq = -EINVAL;

out:
        return irq;
}

static void dwc_gadget_release(struct device *dev)
{
        struct usb_gadget *gadget = container_of(dev, struct usb_gadget, dev);

        kfree(gadget);
}

/**
 * dwc3_gadget_init - initializes gadget related registers
 * @dwc: pointer to our controller context structure
 *
 * Returns 0 on success otherwise negative errno.
 */
int dwc3_gadget_init(struct dwc3 *dwc)
{
        int ret;
        int irq;
        struct device *dev;

        irq = dwc3_gadget_get_irq(dwc);
        if (irq < 0) {
                ret = irq;
                goto err0;
        }

        dwc->irq_gadget = irq;

        dwc->ep0_trb = dma_alloc_coherent(dwc->sysdev,
                                          sizeof(*dwc->ep0_trb) * 2,
                                          &dwc->ep0_trb_addr, GFP_KERNEL);
        if (!dwc->ep0_trb) {
                dev_err(dwc->dev, "failed to allocate ep0 trb\n");
                ret = -ENOMEM;
                goto err0;
        }

        dwc->setup_buf = kzalloc(DWC3_EP0_SETUP_SIZE, GFP_KERNEL);
        if (!dwc->setup_buf) {
                ret = -ENOMEM;
                goto err1;
        }

        dwc->bounce = dma_alloc_coherent(dwc->sysdev, DWC3_BOUNCE_SIZE,
                        &dwc->bounce_addr, GFP_KERNEL);
        if (!dwc->bounce) {
                ret = -ENOMEM;
                goto err2;
        }

        init_completion(&dwc->ep0_in_setup);
        dwc->gadget = kzalloc(sizeof(struct usb_gadget), GFP_KERNEL);
        if (!dwc->gadget) {
                ret = -ENOMEM;
                goto err3;
        }


        usb_initialize_gadget(dwc->dev, dwc->gadget, dwc_gadget_release);
        dev                             = &dwc->gadget->dev;
        dev->platform_data              = dwc;
        dwc->gadget->ops                = &dwc3_gadget_ops;
        dwc->gadget->speed              = USB_SPEED_UNKNOWN;
        dwc->gadget->sg_supported       = true;
        dwc->gadget->name               = "dwc3-gadget";
        dwc->gadget->lpm_capable        = true;

        /*
         * FIXME We might be setting max_speed to <SUPER, however versions
         * <2.20a of dwc3 have an issue with metastability (documented
         * elsewhere in this driver) which tells us we can't set max speed to
         * anything lower than SUPER.
         *
         * Because gadget.max_speed is only used by composite.c and function
         * drivers (i.e. it won't go into dwc3's registers) we are allowing this
         * to happen so we avoid sending SuperSpeed Capability descriptor
         * together with our BOS descriptor as that could confuse host into
         * thinking we can handle super speed.
         *
         * Note that, in fact, we won't even support GetBOS requests when speed
         * is less than super speed because we don't have means, yet, to tell
         * composite.c that we are USB 2.0 + LPM ECN.
         */
        if (DWC3_VER_IS_PRIOR(DWC3, 220A) &&
            !dwc->dis_metastability_quirk)
                dev_info(dwc->dev, "changing max_speed on rev %08x\n",
                                dwc->revision);

        dwc->gadget->max_speed          = dwc->maximum_speed;

        /*
         * REVISIT: Here we should clear all pending IRQs to be
         * sure we're starting from a well known location.
         */

        ret = dwc3_gadget_init_endpoints(dwc, dwc->num_eps);
        if (ret)
                goto err4;

        ret = usb_add_gadget(dwc->gadget);
        if (ret) {
                dev_err(dwc->dev, "failed to add gadget\n");
                goto err5;
        }

        dwc3_gadget_set_speed(dwc->gadget, dwc->maximum_speed);

        return 0;

err5:
        dwc3_gadget_free_endpoints(dwc);
err4:
        usb_put_gadget(dwc->gadget);
err3:
        dma_free_coherent(dwc->sysdev, DWC3_BOUNCE_SIZE, dwc->bounce,
                        dwc->bounce_addr);

err2:
        kfree(dwc->setup_buf);

err1:
        dma_free_coherent(dwc->sysdev, sizeof(*dwc->ep0_trb) * 2,
                        dwc->ep0_trb, dwc->ep0_trb_addr);

err0:
        return ret;
}

/* -------------------------------------------------------------------------- */

void dwc3_gadget_exit(struct dwc3 *dwc)
{
        usb_del_gadget_udc(dwc->gadget);
        dwc3_gadget_free_endpoints(dwc);
        dma_free_coherent(dwc->sysdev, DWC3_BOUNCE_SIZE, dwc->bounce,
                          dwc->bounce_addr);
        kfree(dwc->setup_buf);
        dma_free_coherent(dwc->sysdev, sizeof(*dwc->ep0_trb) * 2,
                          dwc->ep0_trb, dwc->ep0_trb_addr);
}

int dwc3_gadget_suspend(struct dwc3 *dwc)
{
        if (!dwc->gadget_driver)
                return 0;

        dwc3_gadget_run_stop(dwc, false, false);
        dwc3_disconnect_gadget(dwc);
        __dwc3_gadget_stop(dwc);

        return 0;
}

int dwc3_gadget_resume(struct dwc3 *dwc)
{
        int                     ret;

        if (!dwc->gadget_driver)
                return 0;

        ret = __dwc3_gadget_start(dwc);
        if (ret < 0)
                goto err0;

        ret = dwc3_gadget_run_stop(dwc, true, false);
        if (ret < 0)
                goto err1;

        return 0;

err1:
        __dwc3_gadget_stop(dwc);

err0:
        return ret;
}

void dwc3_gadget_process_pending_events(struct dwc3 *dwc)
{
        if (dwc->pending_events) {
                dwc3_interrupt(dwc->irq_gadget, dwc->ev_buf);
                dwc->pending_events = false;
                enable_irq(dwc->irq_gadget);
        }
}