[linux-2.6-microblaze.git] / drivers / hwtracing / coresight / coresight-tmc-etr.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright(C) 2016 Linaro Limited. All rights reserved.
 * Author: Mathieu Poirier <mathieu.poirier@linaro.org>
 */

#include <linux/atomic.h>
#include <linux/coresight.h>
#include <linux/dma-mapping.h>
#include <linux/iommu.h>
#include <linux/idr.h>
#include <linux/mutex.h>
#include <linux/refcount.h>
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/vmalloc.h>
#include "coresight-catu.h"
#include "coresight-etm-perf.h"
#include "coresight-priv.h"
#include "coresight-tmc.h"

struct etr_flat_buf {
        struct device   *dev;
        dma_addr_t      daddr;
        void            *vaddr;
        size_t          size;
};

/*
 * etr_perf_buffer - Perf buffer used for ETR
 * @drvdata             - The ETR drvdaga this buffer has been allocated for.
 * @etr_buf             - Actual buffer used by the ETR
 * @pid                 - The PID this etr_perf_buffer belongs to.
 * @snaphost            - Perf session mode
 * @head                - handle->head at the beginning of the session.
 * @nr_pages            - Number of pages in the ring buffer.
 * @pages               - Array of Pages in the ring buffer.
 */
struct etr_perf_buffer {
        struct tmc_drvdata      *drvdata;
        struct etr_buf          *etr_buf;
        pid_t                   pid;
        bool                    snapshot;
        unsigned long           head;
        int                     nr_pages;
        void                    **pages;
};

/* Convert the perf index to an offset within the ETR buffer */
#define PERF_IDX2OFF(idx, buf)  ((idx) % ((buf)->nr_pages << PAGE_SHIFT))

/* Lower limit for ETR hardware buffer */
#define TMC_ETR_PERF_MIN_BUF_SIZE       SZ_1M

/*
 * The TMC ETR SG has a page size of 4K. The SG table contains pointers
 * to 4KB buffers. However, the OS may use a PAGE_SIZE different from
 * 4K (i.e, 16KB or 64KB). This implies that a single OS page could
 * contain more than one SG buffer and tables.
 *
 * A table entry has the following format:
 *
 * ---Bit31------------Bit4-------Bit1-----Bit0--
 * |     Address[39:12]    | SBZ |  Entry Type  |
 * ----------------------------------------------
 *
 * Address: Bits [39:12] of a physical page address. Bits [11:0] are
 *          always zero.
 *
 * Entry type:
 *      b00 - Reserved.
 *      b01 - Last entry in the tables, points to 4K page buffer.
 *      b10 - Normal entry, points to 4K page buffer.
 *      b11 - Link. The address points to the base of next table.
 */

typedef u32 sgte_t;

#define ETR_SG_PAGE_SHIFT               12
#define ETR_SG_PAGE_SIZE                (1UL << ETR_SG_PAGE_SHIFT)
#define ETR_SG_PAGES_PER_SYSPAGE        (PAGE_SIZE / ETR_SG_PAGE_SIZE)
#define ETR_SG_PTRS_PER_PAGE            (ETR_SG_PAGE_SIZE / sizeof(sgte_t))
#define ETR_SG_PTRS_PER_SYSPAGE         (PAGE_SIZE / sizeof(sgte_t))

#define ETR_SG_ET_MASK                  0x3
#define ETR_SG_ET_LAST                  0x1
#define ETR_SG_ET_NORMAL                0x2
#define ETR_SG_ET_LINK                  0x3

#define ETR_SG_ADDR_SHIFT               4

#define ETR_SG_ENTRY(addr, type) \
        (sgte_t)((((addr) >> ETR_SG_PAGE_SHIFT) << ETR_SG_ADDR_SHIFT) | \
                 (type & ETR_SG_ET_MASK))

#define ETR_SG_ADDR(entry) \
        (((dma_addr_t)(entry) >> ETR_SG_ADDR_SHIFT) << ETR_SG_PAGE_SHIFT)
#define ETR_SG_ET(entry)                ((entry) & ETR_SG_ET_MASK)

/*
 * struct etr_sg_table : ETR SG Table
 * @sg_table:           Generic SG Table holding the data/table pages.
 * @hwaddr:             hwaddress used by the TMC, which is the base
 *                      address of the table.
 */
struct etr_sg_table {
        struct tmc_sg_table     *sg_table;
        dma_addr_t              hwaddr;
};

/*
 * tmc_etr_sg_table_entries: Total number of table entries required to map
 * @nr_pages system pages.
 *
 * We need to map @nr_pages * ETR_SG_PAGES_PER_SYSPAGE data pages.
 * Each TMC page can map (ETR_SG_PTRS_PER_PAGE - 1) buffer pointers,
 * with the last entry pointing to another page of table entries.
 * If we spill over to a new page for mapping 1 entry, we could as
 * well replace the link entry of the previous page with the last entry.
 */
static inline unsigned long __attribute_const__
tmc_etr_sg_table_entries(int nr_pages)
{
        unsigned long nr_sgpages = nr_pages * ETR_SG_PAGES_PER_SYSPAGE;
        unsigned long nr_sglinks = nr_sgpages / (ETR_SG_PTRS_PER_PAGE - 1);
        /*
         * If we spill over to a new page for 1 entry, we could as well
         * make it the LAST entry in the previous page, skipping the Link
         * address.
         */
        if (nr_sglinks && (nr_sgpages % (ETR_SG_PTRS_PER_PAGE - 1) < 2))
                nr_sglinks--;
        return nr_sgpages + nr_sglinks;
}

/*
 * tmc_pages_get_offset:  Go through all the pages in the tmc_pages
 * and map the device address @addr to an offset within the virtual
 * contiguous buffer.
 */
static long
tmc_pages_get_offset(struct tmc_pages *tmc_pages, dma_addr_t addr)
{
        int i;
        dma_addr_t page_start;

        for (i = 0; i < tmc_pages->nr_pages; i++) {
                page_start = tmc_pages->daddrs[i];
                if (addr >= page_start && addr < (page_start + PAGE_SIZE))
                        return i * PAGE_SIZE + (addr - page_start);
        }

        return -EINVAL;
}

/*
 * tmc_pages_free : Unmap and free the pages used by tmc_pages.
 * If the pages were not allocated in tmc_pages_alloc(), we would
 * simply drop the refcount.
 */
static void tmc_pages_free(struct tmc_pages *tmc_pages,
                           struct device *dev, enum dma_data_direction dir)
{
        int i;
        struct device *real_dev = dev->parent;

        for (i = 0; i < tmc_pages->nr_pages; i++) {
                if (tmc_pages->daddrs && tmc_pages->daddrs[i])
                        dma_unmap_page(real_dev, tmc_pages->daddrs[i],
                                         PAGE_SIZE, dir);
                if (tmc_pages->pages && tmc_pages->pages[i])
                        __free_page(tmc_pages->pages[i]);
        }

        kfree(tmc_pages->pages);
        kfree(tmc_pages->daddrs);
        tmc_pages->pages = NULL;
        tmc_pages->daddrs = NULL;
        tmc_pages->nr_pages = 0;
}

/*
 * tmc_pages_alloc : Allocate and map pages for a given @tmc_pages.
 * If @pages is not NULL, the list of page virtual addresses are
 * used as the data pages. The pages are then dma_map'ed for @dev
 * with dma_direction @dir.
 *
 * Returns 0 upon success, else the error number.
 */
static int tmc_pages_alloc(struct tmc_pages *tmc_pages,
                           struct device *dev, int node,
                           enum dma_data_direction dir, void **pages)
{
        int i, nr_pages;
        dma_addr_t paddr;
        struct page *page;
        struct device *real_dev = dev->parent;

        nr_pages = tmc_pages->nr_pages;
        tmc_pages->daddrs = kcalloc(nr_pages, sizeof(*tmc_pages->daddrs),
                                         GFP_KERNEL);
        if (!tmc_pages->daddrs)
                return -ENOMEM;
        tmc_pages->pages = kcalloc(nr_pages, sizeof(*tmc_pages->pages),
                                         GFP_KERNEL);
        if (!tmc_pages->pages) {
                kfree(tmc_pages->daddrs);
                tmc_pages->daddrs = NULL;
                return -ENOMEM;
        }

        for (i = 0; i < nr_pages; i++) {
                if (pages && pages[i]) {
                        page = virt_to_page(pages[i]);
                        /* Hold a refcount on the page */
                        get_page(page);
                } else {
                        page = alloc_pages_node(node,
                                                GFP_KERNEL | __GFP_ZERO, 0);
                }
                paddr = dma_map_page(real_dev, page, 0, PAGE_SIZE, dir);
                if (dma_mapping_error(real_dev, paddr))
                        goto err;
                tmc_pages->daddrs[i] = paddr;
                tmc_pages->pages[i] = page;
        }
        return 0;
err:
        tmc_pages_free(tmc_pages, dev, dir);
        return -ENOMEM;
}

static inline long
tmc_sg_get_data_page_offset(struct tmc_sg_table *sg_table, dma_addr_t addr)
{
        return tmc_pages_get_offset(&sg_table->data_pages, addr);
}

static inline void tmc_free_table_pages(struct tmc_sg_table *sg_table)
{
        if (sg_table->table_vaddr)
                vunmap(sg_table->table_vaddr);
        tmc_pages_free(&sg_table->table_pages, sg_table->dev, DMA_TO_DEVICE);
}

static void tmc_free_data_pages(struct tmc_sg_table *sg_table)
{
        if (sg_table->data_vaddr)
                vunmap(sg_table->data_vaddr);
        tmc_pages_free(&sg_table->data_pages, sg_table->dev, DMA_FROM_DEVICE);
}

void tmc_free_sg_table(struct tmc_sg_table *sg_table)
{
        tmc_free_table_pages(sg_table);
        tmc_free_data_pages(sg_table);
}

/*
 * Alloc pages for the table. Since this will be used by the device,
 * allocate the pages closer to the device (i.e, dev_to_node(dev)
 * rather than the CPU node).
 */
static int tmc_alloc_table_pages(struct tmc_sg_table *sg_table)
{
        int rc;
        struct tmc_pages *table_pages = &sg_table->table_pages;

        rc = tmc_pages_alloc(table_pages, sg_table->dev,
                             dev_to_node(sg_table->dev),
                             DMA_TO_DEVICE, NULL);
        if (rc)
                return rc;
        sg_table->table_vaddr = vmap(table_pages->pages,
                                     table_pages->nr_pages,
                                     VM_MAP,
                                     PAGE_KERNEL);
        if (!sg_table->table_vaddr)
                rc = -ENOMEM;
        else
                sg_table->table_daddr = table_pages->daddrs[0];
        return rc;
}

static int tmc_alloc_data_pages(struct tmc_sg_table *sg_table, void **pages)
{
        int rc;

        /* Allocate data pages on the node requested by the caller */
        rc = tmc_pages_alloc(&sg_table->data_pages,
                             sg_table->dev, sg_table->node,
                             DMA_FROM_DEVICE, pages);
        if (!rc) {
                sg_table->data_vaddr = vmap(sg_table->data_pages.pages,
                                            sg_table->data_pages.nr_pages,
                                            VM_MAP,
                                            PAGE_KERNEL);
                if (!sg_table->data_vaddr)
                        rc = -ENOMEM;
        }
        return rc;
}

/*
 * tmc_alloc_sg_table: Allocate and setup dma pages for the TMC SG table
 * and data buffers. TMC writes to the data buffers and reads from the SG
 * Table pages.
 *
 * @dev         - Coresight device to which page should be DMA mapped.
 * @node        - Numa node for mem allocations
 * @nr_tpages   - Number of pages for the table entries.
 * @nr_dpages   - Number of pages for Data buffer.
 * @pages       - Optional list of virtual address of pages.
 */
struct tmc_sg_table *tmc_alloc_sg_table(struct device *dev,
                                        int node,
                                        int nr_tpages,
                                        int nr_dpages,
                                        void **pages)
{
        long rc;
        struct tmc_sg_table *sg_table;

        sg_table = kzalloc(sizeof(*sg_table), GFP_KERNEL);
        if (!sg_table)
                return ERR_PTR(-ENOMEM);
        sg_table->data_pages.nr_pages = nr_dpages;
        sg_table->table_pages.nr_pages = nr_tpages;
        sg_table->node = node;
        sg_table->dev = dev;

        rc  = tmc_alloc_data_pages(sg_table, pages);
        if (!rc)
                rc = tmc_alloc_table_pages(sg_table);
        if (rc) {
                tmc_free_sg_table(sg_table);
                kfree(sg_table);
                return ERR_PTR(rc);
        }

        return sg_table;
}

/*
 * tmc_sg_table_sync_data_range: Sync the data buffer written
 * by the device from @offset upto a @size bytes.
 */
void tmc_sg_table_sync_data_range(struct tmc_sg_table *table,
                                  u64 offset, u64 size)
{
        int i, index, start;
        int npages = DIV_ROUND_UP(size, PAGE_SIZE);
        struct device *real_dev = table->dev->parent;
        struct tmc_pages *data = &table->data_pages;

        start = offset >> PAGE_SHIFT;
        for (i = start; i < (start + npages); i++) {
                index = i % data->nr_pages;
                dma_sync_single_for_cpu(real_dev, data->daddrs[index],
                                        PAGE_SIZE, DMA_FROM_DEVICE);
        }
}

/* tmc_sg_sync_table: Sync the page table */
void tmc_sg_table_sync_table(struct tmc_sg_table *sg_table)
{
        int i;
        struct device *real_dev = sg_table->dev->parent;
        struct tmc_pages *table_pages = &sg_table->table_pages;

        for (i = 0; i < table_pages->nr_pages; i++)
                dma_sync_single_for_device(real_dev, table_pages->daddrs[i],
                                           PAGE_SIZE, DMA_TO_DEVICE);
}

/*
 * tmc_sg_table_get_data: Get the buffer pointer for data @offset
 * in the SG buffer. The @bufpp is updated to point to the buffer.
 * Returns :
 *      the length of linear data available at @offset.
 *      or
 *      <= 0 if no data is available.
 */
ssize_t tmc_sg_table_get_data(struct tmc_sg_table *sg_table,
                              u64 offset, size_t len, char **bufpp)
{
        size_t size;
        int pg_idx = offset >> PAGE_SHIFT;
        int pg_offset = offset & (PAGE_SIZE - 1);
        struct tmc_pages *data_pages = &sg_table->data_pages;

        size = tmc_sg_table_buf_size(sg_table);
        if (offset >= size)
                return -EINVAL;

        /* Make sure we don't go beyond the end */
        len = (len < (size - offset)) ? len : size - offset;
        /* Respect the page boundaries */
        len = (len < (PAGE_SIZE - pg_offset)) ? len : (PAGE_SIZE - pg_offset);
        if (len > 0)
                *bufpp = page_address(data_pages->pages[pg_idx]) + pg_offset;
        return len;
}

#ifdef ETR_SG_DEBUG
/* Map a dma address to virtual address */
static unsigned long
tmc_sg_daddr_to_vaddr(struct tmc_sg_table *sg_table,
                      dma_addr_t addr, bool table)
{
        long offset;
        unsigned long base;
        struct tmc_pages *tmc_pages;

        if (table) {
                tmc_pages = &sg_table->table_pages;
                base = (unsigned long)sg_table->table_vaddr;
        } else {
                tmc_pages = &sg_table->data_pages;
                base = (unsigned long)sg_table->data_vaddr;
        }

        offset = tmc_pages_get_offset(tmc_pages, addr);
        if (offset < 0)
                return 0;
        return base + offset;
}

/* Dump the given sg_table */
static void tmc_etr_sg_table_dump(struct etr_sg_table *etr_table)
{
        sgte_t *ptr;
        int i = 0;
        dma_addr_t addr;
        struct tmc_sg_table *sg_table = etr_table->sg_table;

        ptr = (sgte_t *)tmc_sg_daddr_to_vaddr(sg_table,
                                              etr_table->hwaddr, true);
        while (ptr) {
                addr = ETR_SG_ADDR(*ptr);
                switch (ETR_SG_ET(*ptr)) {
                case ETR_SG_ET_NORMAL:
                        dev_dbg(sg_table->dev,
                                "%05d: %p\t:[N] 0x%llx\n", i, ptr, addr);
                        ptr++;
                        break;
                case ETR_SG_ET_LINK:
                        dev_dbg(sg_table->dev,
                                "%05d: *** %p\t:{L} 0x%llx ***\n",
                                 i, ptr, addr);
                        ptr = (sgte_t *)tmc_sg_daddr_to_vaddr(sg_table,
                                                              addr, true);
                        break;
                case ETR_SG_ET_LAST:
                        dev_dbg(sg_table->dev,
                                "%05d: ### %p\t:[L] 0x%llx ###\n",
                                 i, ptr, addr);
                        return;
                default:
                        dev_dbg(sg_table->dev,
                                "%05d: xxx %p\t:[INVALID] 0x%llx xxx\n",
                                 i, ptr, addr);
                        return;
                }
                i++;
        }
        dev_dbg(sg_table->dev, "******* End of Table *****\n");
}
#else
static inline void tmc_etr_sg_table_dump(struct etr_sg_table *etr_table) {}
#endif

/*
 * Populate the SG Table page table entries from table/data
 * pages allocated. Each Data page has ETR_SG_PAGES_PER_SYSPAGE SG pages.
 * So does a Table page. So we keep track of indices of the tables
 * in each system page and move the pointers accordingly.
 */
#define INC_IDX_ROUND(idx, size) ((idx) = ((idx) + 1) % (size))
static void tmc_etr_sg_table_populate(struct etr_sg_table *etr_table)
{
        dma_addr_t paddr;
        int i, type, nr_entries;
        int tpidx = 0; /* index to the current system table_page */
        int sgtidx = 0; /* index to the sg_table within the current syspage */
        int sgtentry = 0; /* the entry within the sg_table */
        int dpidx = 0; /* index to the current system data_page */
        int spidx = 0; /* index to the SG page within the current data page */
        sgte_t *ptr; /* pointer to the table entry to fill */
        struct tmc_sg_table *sg_table = etr_table->sg_table;
        dma_addr_t *table_daddrs = sg_table->table_pages.daddrs;
        dma_addr_t *data_daddrs = sg_table->data_pages.daddrs;

        nr_entries = tmc_etr_sg_table_entries(sg_table->data_pages.nr_pages);
        /*
         * Use the contiguous virtual address of the table to update entries.
         */
        ptr = sg_table->table_vaddr;
        /*
         * Fill all the entries, except the last entry to avoid special
         * checks within the loop.
         */
        for (i = 0; i < nr_entries - 1; i++) {
                if (sgtentry == ETR_SG_PTRS_PER_PAGE - 1) {
                        /*
                         * Last entry in a sg_table page is a link address to
                         * the next table page. If this sg_table is the last
                         * one in the system page, it links to the first
                         * sg_table in the next system page. Otherwise, it
                         * links to the next sg_table page within the system
                         * page.
                         */
                        if (sgtidx == ETR_SG_PAGES_PER_SYSPAGE - 1) {
                                paddr = table_daddrs[tpidx + 1];
                        } else {
                                paddr = table_daddrs[tpidx] +
                                        (ETR_SG_PAGE_SIZE * (sgtidx + 1));
                        }
                        type = ETR_SG_ET_LINK;
                } else {
                        /*
                         * Update the indices to the data_pages to point to the
                         * next sg_page in the data buffer.
                         */
                        type = ETR_SG_ET_NORMAL;
                        paddr = data_daddrs[dpidx] + spidx * ETR_SG_PAGE_SIZE;
                        if (!INC_IDX_ROUND(spidx, ETR_SG_PAGES_PER_SYSPAGE))
                                dpidx++;
                }
                *ptr++ = ETR_SG_ENTRY(paddr, type);
                /*
                 * Move to the next table pointer, moving the table page index
                 * if necessary
                 */
                if (!INC_IDX_ROUND(sgtentry, ETR_SG_PTRS_PER_PAGE)) {
                        if (!INC_IDX_ROUND(sgtidx, ETR_SG_PAGES_PER_SYSPAGE))
                                tpidx++;
                }
        }

        /* Set up the last entry, which is always a data pointer */
        paddr = data_daddrs[dpidx] + spidx * ETR_SG_PAGE_SIZE;
        *ptr++ = ETR_SG_ENTRY(paddr, ETR_SG_ET_LAST);
}

/*
 * tmc_init_etr_sg_table: Allocate a TMC ETR SG table, data buffer of @size and
 * populate the table.
 *
 * @dev         - Device pointer for the TMC
 * @node        - NUMA node where the memory should be allocated
 * @size        - Total size of the data buffer
 * @pages       - Optional list of page virtual address
 */
static struct etr_sg_table *
tmc_init_etr_sg_table(struct device *dev, int node,
                      unsigned long size, void **pages)
{
        int nr_entries, nr_tpages;
        int nr_dpages = size >> PAGE_SHIFT;
        struct tmc_sg_table *sg_table;
        struct etr_sg_table *etr_table;

        etr_table = kzalloc(sizeof(*etr_table), GFP_KERNEL);
        if (!etr_table)
                return ERR_PTR(-ENOMEM);
        nr_entries = tmc_etr_sg_table_entries(nr_dpages);
        nr_tpages = DIV_ROUND_UP(nr_entries, ETR_SG_PTRS_PER_SYSPAGE);

        sg_table = tmc_alloc_sg_table(dev, node, nr_tpages, nr_dpages, pages);
        if (IS_ERR(sg_table)) {
                kfree(etr_table);
                return ERR_CAST(sg_table);
        }

        etr_table->sg_table = sg_table;
        /* TMC should use table base address for DBA */
        etr_table->hwaddr = sg_table->table_daddr;
        tmc_etr_sg_table_populate(etr_table);
        /* Sync the table pages for the HW */
        tmc_sg_table_sync_table(sg_table);
        tmc_etr_sg_table_dump(etr_table);

        return etr_table;
}

/*
 * tmc_etr_alloc_flat_buf: Allocate a contiguous DMA buffer.
 */
static int tmc_etr_alloc_flat_buf(struct tmc_drvdata *drvdata,
                                  struct etr_buf *etr_buf, int node,
                                  void **pages)
{
        struct etr_flat_buf *flat_buf;
        struct device *real_dev = drvdata->csdev->dev.parent;

        /* We cannot reuse existing pages for flat buf */
        if (pages)
                return -EINVAL;

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

        flat_buf->vaddr = dma_alloc_coherent(real_dev, etr_buf->size,
                                             &flat_buf->daddr, GFP_KERNEL);
        if (!flat_buf->vaddr) {
                kfree(flat_buf);
                return -ENOMEM;
        }

        flat_buf->size = etr_buf->size;
        flat_buf->dev = &drvdata->csdev->dev;
        etr_buf->hwaddr = flat_buf->daddr;
        etr_buf->mode = ETR_MODE_FLAT;
        etr_buf->private = flat_buf;
        return 0;
}

static void tmc_etr_free_flat_buf(struct etr_buf *etr_buf)
{
        struct etr_flat_buf *flat_buf = etr_buf->private;

        if (flat_buf && flat_buf->daddr) {
                struct device *real_dev = flat_buf->dev->parent;

                dma_free_coherent(real_dev, flat_buf->size,
                                  flat_buf->vaddr, flat_buf->daddr);
        }
        kfree(flat_buf);
}

static void tmc_etr_sync_flat_buf(struct etr_buf *etr_buf, u64 rrp, u64 rwp)
{
        /*
         * Adjust the buffer to point to the beginning of the trace data
         * and update the available trace data.
         */
        etr_buf->offset = rrp - etr_buf->hwaddr;
        if (etr_buf->full)
                etr_buf->len = etr_buf->size;
        else
                etr_buf->len = rwp - rrp;
}

static ssize_t tmc_etr_get_data_flat_buf(struct etr_buf *etr_buf,
                                         u64 offset, size_t len, char **bufpp)
{
        struct etr_flat_buf *flat_buf = etr_buf->private;

        *bufpp = (char *)flat_buf->vaddr + offset;
        /*
         * tmc_etr_buf_get_data already adjusts the length to handle
         * buffer wrapping around.
         */
        return len;
}

static const struct etr_buf_operations etr_flat_buf_ops = {
        .alloc = tmc_etr_alloc_flat_buf,
        .free = tmc_etr_free_flat_buf,
        .sync = tmc_etr_sync_flat_buf,
        .get_data = tmc_etr_get_data_flat_buf,
};

/*
 * tmc_etr_alloc_sg_buf: Allocate an SG buf @etr_buf. Setup the parameters
 * appropriately.
 */
static int tmc_etr_alloc_sg_buf(struct tmc_drvdata *drvdata,
                                struct etr_buf *etr_buf, int node,
                                void **pages)
{
        struct etr_sg_table *etr_table;
        struct device *dev = &drvdata->csdev->dev;

        etr_table = tmc_init_etr_sg_table(dev, node,
                                          etr_buf->size, pages);
        if (IS_ERR(etr_table))
                return -ENOMEM;
        etr_buf->hwaddr = etr_table->hwaddr;
        etr_buf->mode = ETR_MODE_ETR_SG;
        etr_buf->private = etr_table;
        return 0;
}

static void tmc_etr_free_sg_buf(struct etr_buf *etr_buf)
{
        struct etr_sg_table *etr_table = etr_buf->private;

        if (etr_table) {
                tmc_free_sg_table(etr_table->sg_table);
                kfree(etr_table);
        }
}

static ssize_t tmc_etr_get_data_sg_buf(struct etr_buf *etr_buf, u64 offset,
                                       size_t len, char **bufpp)
{
        struct etr_sg_table *etr_table = etr_buf->private;

        return tmc_sg_table_get_data(etr_table->sg_table, offset, len, bufpp);
}

static void tmc_etr_sync_sg_buf(struct etr_buf *etr_buf, u64 rrp, u64 rwp)
{
        long r_offset, w_offset;
        struct etr_sg_table *etr_table = etr_buf->private;
        struct tmc_sg_table *table = etr_table->sg_table;

        /* Convert hw address to offset in the buffer */
        r_offset = tmc_sg_get_data_page_offset(table, rrp);
        if (r_offset < 0) {
                dev_warn(table->dev,
                         "Unable to map RRP %llx to offset\n", rrp);
                etr_buf->len = 0;
                return;
        }

        w_offset = tmc_sg_get_data_page_offset(table, rwp);
        if (w_offset < 0) {
                dev_warn(table->dev,
                         "Unable to map RWP %llx to offset\n", rwp);
                etr_buf->len = 0;
                return;
        }

        etr_buf->offset = r_offset;
        if (etr_buf->full)
                etr_buf->len = etr_buf->size;
        else
                etr_buf->len = ((w_offset < r_offset) ? etr_buf->size : 0) +
                                w_offset - r_offset;
        tmc_sg_table_sync_data_range(table, r_offset, etr_buf->len);
}

static const struct etr_buf_operations etr_sg_buf_ops = {
        .alloc = tmc_etr_alloc_sg_buf,
        .free = tmc_etr_free_sg_buf,
        .sync = tmc_etr_sync_sg_buf,
        .get_data = tmc_etr_get_data_sg_buf,
};

/*
 * TMC ETR could be connected to a CATU device, which can provide address
 * translation service. This is represented by the Output port of the TMC
 * (ETR) connected to the input port of the CATU.
 *
 * Returns      : coresight_device ptr for the CATU device if a CATU is found.
 *              : NULL otherwise.
 */
struct coresight_device *
tmc_etr_get_catu_device(struct tmc_drvdata *drvdata)
{
        int i;
        struct coresight_device *tmp, *etr = drvdata->csdev;

        if (!IS_ENABLED(CONFIG_CORESIGHT_CATU))
                return NULL;

        for (i = 0; i < etr->pdata->nr_outport; i++) {
                tmp = etr->pdata->conns[i].child_dev;
                if (tmp && coresight_is_catu_device(tmp))
                        return tmp;
        }

        return NULL;
}

static inline int tmc_etr_enable_catu(struct tmc_drvdata *drvdata,
                                      struct etr_buf *etr_buf)
{
        struct coresight_device *catu = tmc_etr_get_catu_device(drvdata);

        if (catu && helper_ops(catu)->enable)
                return helper_ops(catu)->enable(catu, etr_buf);
        return 0;
}

static inline void tmc_etr_disable_catu(struct tmc_drvdata *drvdata)
{
        struct coresight_device *catu = tmc_etr_get_catu_device(drvdata);

        if (catu && helper_ops(catu)->disable)
                helper_ops(catu)->disable(catu, drvdata->etr_buf);
}

static const struct etr_buf_operations *etr_buf_ops[] = {
        [ETR_MODE_FLAT] = &etr_flat_buf_ops,
        [ETR_MODE_ETR_SG] = &etr_sg_buf_ops,
        [ETR_MODE_CATU] = IS_ENABLED(CONFIG_CORESIGHT_CATU)
                                                ? &etr_catu_buf_ops : NULL,
};

static inline int tmc_etr_mode_alloc_buf(int mode,
                                         struct tmc_drvdata *drvdata,
                                         struct etr_buf *etr_buf, int node,
                                         void **pages)
{
        int rc = -EINVAL;

        switch (mode) {
        case ETR_MODE_FLAT:
        case ETR_MODE_ETR_SG:
        case ETR_MODE_CATU:
                if (etr_buf_ops[mode] && etr_buf_ops[mode]->alloc)
                        rc = etr_buf_ops[mode]->alloc(drvdata, etr_buf,
                                                      node, pages);
                if (!rc)
                        etr_buf->ops = etr_buf_ops[mode];
                return rc;
        default:
                return -EINVAL;
        }
}

/*
 * tmc_alloc_etr_buf: Allocate a buffer use by ETR.
 * @drvdata     : ETR device details.
 * @size        : size of the requested buffer.
 * @flags       : Required properties for the buffer.
 * @node        : Node for memory allocations.
 * @pages       : An optional list of pages.
 */
static struct etr_buf *tmc_alloc_etr_buf(struct tmc_drvdata *drvdata,
                                         ssize_t size, int flags,
                                         int node, void **pages)
{
        int rc = -ENOMEM;
        bool has_etr_sg, has_iommu;
        bool has_sg, has_catu;
        struct etr_buf *etr_buf;
        struct device *dev = &drvdata->csdev->dev;

        has_etr_sg = tmc_etr_has_cap(drvdata, TMC_ETR_SG);
        has_iommu = iommu_get_domain_for_dev(dev->parent);
        has_catu = !!tmc_etr_get_catu_device(drvdata);

        has_sg = has_catu || has_etr_sg;

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

        etr_buf->size = size;

        /*
         * If we have to use an existing list of pages, we cannot reliably
         * use a contiguous DMA memory (even if we have an IOMMU). Otherwise,
         * we use the contiguous DMA memory if at least one of the following
         * conditions is true:
         *  a) The ETR cannot use Scatter-Gather.
         *  b) we have a backing IOMMU
         *  c) The requested memory size is smaller (< 1M).
         *
         * Fallback to available mechanisms.
         *
         */
        if (!pages &&
            (!has_sg || has_iommu || size < SZ_1M))
                rc = tmc_etr_mode_alloc_buf(ETR_MODE_FLAT, drvdata,
                                            etr_buf, node, pages);
        if (rc && has_etr_sg)
                rc = tmc_etr_mode_alloc_buf(ETR_MODE_ETR_SG, drvdata,
                                            etr_buf, node, pages);
        if (rc && has_catu)
                rc = tmc_etr_mode_alloc_buf(ETR_MODE_CATU, drvdata,
                                            etr_buf, node, pages);
        if (rc) {
                kfree(etr_buf);
                return ERR_PTR(rc);
        }

        refcount_set(&etr_buf->refcount, 1);
        dev_dbg(dev, "allocated buffer of size %ldKB in mode %d\n",
                (unsigned long)size >> 10, etr_buf->mode);
        return etr_buf;
}

static void tmc_free_etr_buf(struct etr_buf *etr_buf)
{
        WARN_ON(!etr_buf->ops || !etr_buf->ops->free);
        etr_buf->ops->free(etr_buf);
        kfree(etr_buf);
}

/*
 * tmc_etr_buf_get_data: Get the pointer the trace data at @offset
 * with a maximum of @len bytes.
 * Returns: The size of the linear data available @pos, with *bufpp
 * updated to point to the buffer.
 */
static ssize_t tmc_etr_buf_get_data(struct etr_buf *etr_buf,
                                    u64 offset, size_t len, char **bufpp)
{
        /* Adjust the length to limit this transaction to end of buffer */
        len = (len < (etr_buf->size - offset)) ? len : etr_buf->size - offset;

        return etr_buf->ops->get_data(etr_buf, (u64)offset, len, bufpp);
}

static inline s64
tmc_etr_buf_insert_barrier_packet(struct etr_buf *etr_buf, u64 offset)
{
        ssize_t len;
        char *bufp;

        len = tmc_etr_buf_get_data(etr_buf, offset,
                                   CORESIGHT_BARRIER_PKT_SIZE, &bufp);
        if (WARN_ON(len < CORESIGHT_BARRIER_PKT_SIZE))
                return -EINVAL;
        coresight_insert_barrier_packet(bufp);
        return offset + CORESIGHT_BARRIER_PKT_SIZE;
}

/*
 * tmc_sync_etr_buf: Sync the trace buffer availability with drvdata.
 * Makes sure the trace data is synced to the memory for consumption.
 * @etr_buf->offset will hold the offset to the beginning of the trace data
 * within the buffer, with @etr_buf->len bytes to consume.
 */
static void tmc_sync_etr_buf(struct tmc_drvdata *drvdata)
{
        struct etr_buf *etr_buf = drvdata->etr_buf;
        u64 rrp, rwp;
        u32 status;

        rrp = tmc_read_rrp(drvdata);
        rwp = tmc_read_rwp(drvdata);
        status = readl_relaxed(drvdata->base + TMC_STS);

        /*
         * If there were memory errors in the session, truncate the
         * buffer.
         */
        if (WARN_ON_ONCE(status & TMC_STS_MEMERR)) {
                dev_dbg(&drvdata->csdev->dev,
                        "tmc memory error detected, truncating buffer\n");
                etr_buf->len = 0;
                etr_buf->full = 0;
                return;
        }

        etr_buf->full = status & TMC_STS_FULL;

        WARN_ON(!etr_buf->ops || !etr_buf->ops->sync);

        etr_buf->ops->sync(etr_buf, rrp, rwp);

        /* Insert barrier packets at the beginning, if there was an overflow */
        if (etr_buf->full)
                tmc_etr_buf_insert_barrier_packet(etr_buf, etr_buf->offset);
}

static void __tmc_etr_enable_hw(struct tmc_drvdata *drvdata)
{
        u32 axictl, sts;
        struct etr_buf *etr_buf = drvdata->etr_buf;

        CS_UNLOCK(drvdata->base);

        /* Wait for TMCSReady bit to be set */
        tmc_wait_for_tmcready(drvdata);

        writel_relaxed(etr_buf->size / 4, drvdata->base + TMC_RSZ);
        writel_relaxed(TMC_MODE_CIRCULAR_BUFFER, drvdata->base + TMC_MODE);

        axictl = readl_relaxed(drvdata->base + TMC_AXICTL);
        axictl &= ~TMC_AXICTL_CLEAR_MASK;
        axictl |= (TMC_AXICTL_PROT_CTL_B1 | TMC_AXICTL_WR_BURST_16);
        axictl |= TMC_AXICTL_AXCACHE_OS;

        if (tmc_etr_has_cap(drvdata, TMC_ETR_AXI_ARCACHE)) {
                axictl &= ~TMC_AXICTL_ARCACHE_MASK;
                axictl |= TMC_AXICTL_ARCACHE_OS;
        }

        if (etr_buf->mode == ETR_MODE_ETR_SG)
                axictl |= TMC_AXICTL_SCT_GAT_MODE;

        writel_relaxed(axictl, drvdata->base + TMC_AXICTL);
        tmc_write_dba(drvdata, etr_buf->hwaddr);
        /*
         * If the TMC pointers must be programmed before the session,
         * we have to set it properly (i.e, RRP/RWP to base address and
         * STS to "not full").
         */
        if (tmc_etr_has_cap(drvdata, TMC_ETR_SAVE_RESTORE)) {
                tmc_write_rrp(drvdata, etr_buf->hwaddr);
                tmc_write_rwp(drvdata, etr_buf->hwaddr);
                sts = readl_relaxed(drvdata->base + TMC_STS) & ~TMC_STS_FULL;
                writel_relaxed(sts, drvdata->base + TMC_STS);
        }

        writel_relaxed(TMC_FFCR_EN_FMT | TMC_FFCR_EN_TI |
                       TMC_FFCR_FON_FLIN | TMC_FFCR_FON_TRIG_EVT |
                       TMC_FFCR_TRIGON_TRIGIN,
                       drvdata->base + TMC_FFCR);
        writel_relaxed(drvdata->trigger_cntr, drvdata->base + TMC_TRG);
        tmc_enable_hw(drvdata);

        CS_LOCK(drvdata->base);
}

static int tmc_etr_enable_hw(struct tmc_drvdata *drvdata,
                             struct etr_buf *etr_buf)
{
        int rc;

        /* Callers should provide an appropriate buffer for use */
        if (WARN_ON(!etr_buf))
                return -EINVAL;

        if ((etr_buf->mode == ETR_MODE_ETR_SG) &&
            WARN_ON(!tmc_etr_has_cap(drvdata, TMC_ETR_SG)))
                return -EINVAL;

        if (WARN_ON(drvdata->etr_buf))
                return -EBUSY;

        /*
         * If this ETR is connected to a CATU, enable it before we turn
         * this on.
         */
        rc = tmc_etr_enable_catu(drvdata, etr_buf);
        if (rc)
                return rc;
        rc = coresight_claim_device(drvdata->base);
        if (!rc) {
                drvdata->etr_buf = etr_buf;
                __tmc_etr_enable_hw(drvdata);
        }

        return rc;
}

/*
 * Return the available trace data in the buffer (starts at etr_buf->offset,
 * limited by etr_buf->len) from @pos, with a maximum limit of @len,
 * also updating the @bufpp on where to find it. Since the trace data
 * starts at anywhere in the buffer, depending on the RRP, we adjust the
 * @len returned to handle buffer wrapping around.
 *
 * We are protected here by drvdata->reading != 0, which ensures the
 * sysfs_buf stays alive.
 */
ssize_t tmc_etr_get_sysfs_trace(struct tmc_drvdata *drvdata,
                                loff_t pos, size_t len, char **bufpp)
{
        s64 offset;
        ssize_t actual = len;
        struct etr_buf *etr_buf = drvdata->sysfs_buf;

        if (pos + actual > etr_buf->len)
                actual = etr_buf->len - pos;
        if (actual <= 0)
                return actual;

        /* Compute the offset from which we read the data */
        offset = etr_buf->offset + pos;
        if (offset >= etr_buf->size)
                offset -= etr_buf->size;
        return tmc_etr_buf_get_data(etr_buf, offset, actual, bufpp);
}

static struct etr_buf *
tmc_etr_setup_sysfs_buf(struct tmc_drvdata *drvdata)
{
        return tmc_alloc_etr_buf(drvdata, drvdata->size,
                                 0, cpu_to_node(0), NULL);
}

static void
tmc_etr_free_sysfs_buf(struct etr_buf *buf)
{
        if (buf)
                tmc_free_etr_buf(buf);
}

static void tmc_etr_sync_sysfs_buf(struct tmc_drvdata *drvdata)
{
        struct etr_buf *etr_buf = drvdata->etr_buf;

        if (WARN_ON(drvdata->sysfs_buf != etr_buf)) {
                tmc_etr_free_sysfs_buf(drvdata->sysfs_buf);
                drvdata->sysfs_buf = NULL;
        } else {
                tmc_sync_etr_buf(drvdata);
        }
}

static void __tmc_etr_disable_hw(struct tmc_drvdata *drvdata)
{
        CS_UNLOCK(drvdata->base);

        tmc_flush_and_stop(drvdata);
        /*
         * When operating in sysFS mode the content of the buffer needs to be
         * read before the TMC is disabled.
         */
        if (drvdata->mode == CS_MODE_SYSFS)
                tmc_etr_sync_sysfs_buf(drvdata);

        tmc_disable_hw(drvdata);

        CS_LOCK(drvdata->base);

}

static void tmc_etr_disable_hw(struct tmc_drvdata *drvdata)
{
        __tmc_etr_disable_hw(drvdata);
        /* Disable CATU device if this ETR is connected to one */
        tmc_etr_disable_catu(drvdata);
        coresight_disclaim_device(drvdata->base);
        /* Reset the ETR buf used by hardware */
        drvdata->etr_buf = NULL;
}

static int tmc_enable_etr_sink_sysfs(struct coresight_device *csdev)
{
        int ret = 0;
        unsigned long flags;
        struct tmc_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
        struct etr_buf *sysfs_buf = NULL, *new_buf = NULL, *free_buf = NULL;

        /*
         * If we are enabling the ETR from disabled state, we need to make
         * sure we have a buffer with the right size. The etr_buf is not reset
         * immediately after we stop the tracing in SYSFS mode as we wait for
         * the user to collect the data. We may be able to reuse the existing
         * buffer, provided the size matches. Any allocation has to be done
         * with the lock released.
         */
        spin_lock_irqsave(&drvdata->spinlock, flags);
        sysfs_buf = READ_ONCE(drvdata->sysfs_buf);
        if (!sysfs_buf || (sysfs_buf->size != drvdata->size)) {
                spin_unlock_irqrestore(&drvdata->spinlock, flags);

                /* Allocate memory with the locks released */
                free_buf = new_buf = tmc_etr_setup_sysfs_buf(drvdata);
                if (IS_ERR(new_buf))
                        return PTR_ERR(new_buf);

                /* Let's try again */
                spin_lock_irqsave(&drvdata->spinlock, flags);
        }

        if (drvdata->reading || drvdata->mode == CS_MODE_PERF) {
                ret = -EBUSY;
                goto out;
        }

        /*
         * In sysFS mode we can have multiple writers per sink.  Since this
         * sink is already enabled no memory is needed and the HW need not be
         * touched, even if the buffer size has changed.
         */
        if (drvdata->mode == CS_MODE_SYSFS) {
                atomic_inc(csdev->refcnt);
                goto out;
        }

        /*
         * If we don't have a buffer or it doesn't match the requested size,
         * use the buffer allocated above. Otherwise reuse the existing buffer.
         */
        sysfs_buf = READ_ONCE(drvdata->sysfs_buf);
        if (!sysfs_buf || (new_buf && sysfs_buf->size != new_buf->size)) {
                free_buf = sysfs_buf;
                drvdata->sysfs_buf = new_buf;
        }

        ret = tmc_etr_enable_hw(drvdata, drvdata->sysfs_buf);
        if (!ret) {
                drvdata->mode = CS_MODE_SYSFS;
                atomic_inc(csdev->refcnt);
        }
out:
        spin_unlock_irqrestore(&drvdata->spinlock, flags);

        /* Free memory outside the spinlock if need be */
        if (free_buf)
                tmc_etr_free_sysfs_buf(free_buf);

        if (!ret)
                dev_dbg(&csdev->dev, "TMC-ETR enabled\n");

        return ret;
}

/*
 * alloc_etr_buf: Allocate ETR buffer for use by perf.
 * The size of the hardware buffer is dependent on the size configured
 * via sysfs and the perf ring buffer size. We prefer to allocate the
 * largest possible size, scaling down the size by half until it
 * reaches a minimum limit (1M), beyond which we give up.
 */
static struct etr_buf *
alloc_etr_buf(struct tmc_drvdata *drvdata, struct perf_event *event,
              int nr_pages, void **pages, bool snapshot)
{
        int node;
        struct etr_buf *etr_buf;
        unsigned long size;

        node = (event->cpu == -1) ? NUMA_NO_NODE : cpu_to_node(event->cpu);
        /*
         * Try to match the perf ring buffer size if it is larger
         * than the size requested via sysfs.
         */
        if ((nr_pages << PAGE_SHIFT) > drvdata->size) {
                etr_buf = tmc_alloc_etr_buf(drvdata, (nr_pages << PAGE_SHIFT),
                                            0, node, NULL);
                if (!IS_ERR(etr_buf))
                        goto done;
        }

        /*
         * Else switch to configured size for this ETR
         * and scale down until we hit the minimum limit.
         */
        size = drvdata->size;
        do {
                etr_buf = tmc_alloc_etr_buf(drvdata, size, 0, node, NULL);
                if (!IS_ERR(etr_buf))
                        goto done;
                size /= 2;
        } while (size >= TMC_ETR_PERF_MIN_BUF_SIZE);

        return ERR_PTR(-ENOMEM);

done:
        return etr_buf;
}

static struct etr_buf *
get_perf_etr_buf_cpu_wide(struct tmc_drvdata *drvdata,
                          struct perf_event *event, int nr_pages,
                          void **pages, bool snapshot)
{
        int ret;
        pid_t pid = task_pid_nr(event->owner);
        struct etr_buf *etr_buf;

retry:
        /*
         * An etr_perf_buffer is associated with an event and holds a reference
         * to the AUX ring buffer that was created for that event.  In CPU-wide
         * N:1 mode multiple events (one per CPU), each with its own AUX ring
         * buffer, share a sink.  As such an etr_perf_buffer is created for each
         * event but a single etr_buf associated with the ETR is shared between
         * them.  The last event in a trace session will copy the content of the
         * etr_buf to its AUX ring buffer.  Ring buffer associated to other
         * events are simply not used an freed as events are destoyed.  We still
         * need to allocate a ring buffer for each event since we don't know
         * which event will be last.
         */

        /*
         * The first thing to do here is check if an etr_buf has already been
         * allocated for this session.  If so it is shared with this event,
         * otherwise it is created.
         */
        mutex_lock(&drvdata->idr_mutex);
        etr_buf = idr_find(&drvdata->idr, pid);
        if (etr_buf) {
                refcount_inc(&etr_buf->refcount);
                mutex_unlock(&drvdata->idr_mutex);
                return etr_buf;
        }

        /* If we made it here no buffer has been allocated, do so now. */
        mutex_unlock(&drvdata->idr_mutex);

        etr_buf = alloc_etr_buf(drvdata, event, nr_pages, pages, snapshot);
        if (IS_ERR(etr_buf))
                return etr_buf;

        /* Now that we have a buffer, add it to the IDR. */
        mutex_lock(&drvdata->idr_mutex);
        ret = idr_alloc(&drvdata->idr, etr_buf, pid, pid + 1, GFP_KERNEL);
        mutex_unlock(&drvdata->idr_mutex);

        /* Another event with this session ID has allocated this buffer. */
        if (ret == -ENOSPC) {
                tmc_free_etr_buf(etr_buf);
                goto retry;
        }

        /* The IDR can't allocate room for a new session, abandon ship. */
        if (ret == -ENOMEM) {
                tmc_free_etr_buf(etr_buf);
                return ERR_PTR(ret);
        }


        return etr_buf;
}

static struct etr_buf *
get_perf_etr_buf_per_thread(struct tmc_drvdata *drvdata,
                            struct perf_event *event, int nr_pages,
                            void **pages, bool snapshot)
{
        /*
         * In per-thread mode the etr_buf isn't shared, so just go ahead
         * with memory allocation.
         */
        return alloc_etr_buf(drvdata, event, nr_pages, pages, snapshot);
}

static struct etr_buf *
get_perf_etr_buf(struct tmc_drvdata *drvdata, struct perf_event *event,
                 int nr_pages, void **pages, bool snapshot)
{
        if (event->cpu == -1)
                return get_perf_etr_buf_per_thread(drvdata, event, nr_pages,
                                                   pages, snapshot);

        return get_perf_etr_buf_cpu_wide(drvdata, event, nr_pages,
                                         pages, snapshot);
}

static struct etr_perf_buffer *
tmc_etr_setup_perf_buf(struct tmc_drvdata *drvdata, struct perf_event *event,
                       int nr_pages, void **pages, bool snapshot)
{
        int node;
        struct etr_buf *etr_buf;
        struct etr_perf_buffer *etr_perf;

        node = (event->cpu == -1) ? NUMA_NO_NODE : cpu_to_node(event->cpu);

        etr_perf = kzalloc_node(sizeof(*etr_perf), GFP_KERNEL, node);
        if (!etr_perf)
                return ERR_PTR(-ENOMEM);

        etr_buf = get_perf_etr_buf(drvdata, event, nr_pages, pages, snapshot);
        if (!IS_ERR(etr_buf))
                goto done;

        kfree(etr_perf);
        return ERR_PTR(-ENOMEM);

done:
        /*
         * Keep a reference to the ETR this buffer has been allocated for
         * in order to have access to the IDR in tmc_free_etr_buffer().
         */
        etr_perf->drvdata = drvdata;
        etr_perf->etr_buf = etr_buf;

        return etr_perf;
}


static void *tmc_alloc_etr_buffer(struct coresight_device *csdev,
                                  struct perf_event *event, void **pages,
                                  int nr_pages, bool snapshot)
{
        struct etr_perf_buffer *etr_perf;
        struct tmc_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);

        etr_perf = tmc_etr_setup_perf_buf(drvdata, event,
                                          nr_pages, pages, snapshot);
        if (IS_ERR(etr_perf)) {
                dev_dbg(&csdev->dev, "Unable to allocate ETR buffer\n");
                return NULL;
        }

        etr_perf->pid = task_pid_nr(event->owner);
        etr_perf->snapshot = snapshot;
        etr_perf->nr_pages = nr_pages;
        etr_perf->pages = pages;

        return etr_perf;
}

static void tmc_free_etr_buffer(void *config)
{
        struct etr_perf_buffer *etr_perf = config;
        struct tmc_drvdata *drvdata = etr_perf->drvdata;
        struct etr_buf *buf, *etr_buf = etr_perf->etr_buf;

        if (!etr_buf)
                goto free_etr_perf_buffer;

        mutex_lock(&drvdata->idr_mutex);
        /* If we are not the last one to use the buffer, don't touch it. */
        if (!refcount_dec_and_test(&etr_buf->refcount)) {
                mutex_unlock(&drvdata->idr_mutex);
                goto free_etr_perf_buffer;
        }

        /* We are the last one, remove from the IDR and free the buffer. */
        buf = idr_remove(&drvdata->idr, etr_perf->pid);
        mutex_unlock(&drvdata->idr_mutex);

        /*
         * Something went very wrong if the buffer associated with this ID
         * is not the same in the IDR.  Leak to avoid use after free.
         */
        if (buf && WARN_ON(buf != etr_buf))
                goto free_etr_perf_buffer;

        tmc_free_etr_buf(etr_perf->etr_buf);

free_etr_perf_buffer:
        kfree(etr_perf);
}

/*
 * tmc_etr_sync_perf_buffer: Copy the actual trace data from the hardware
 * buffer to the perf ring buffer.
 */
static void tmc_etr_sync_perf_buffer(struct etr_perf_buffer *etr_perf,
                                     unsigned long to_copy)
{
        long bytes;
        long pg_idx, pg_offset, src_offset;
        unsigned long head = etr_perf->head;
        char **dst_pages, *src_buf;
        struct etr_buf *etr_buf = etr_perf->etr_buf;

        head = etr_perf->head;
        pg_idx = head >> PAGE_SHIFT;
        pg_offset = head & (PAGE_SIZE - 1);
        dst_pages = (char **)etr_perf->pages;
        src_offset = etr_buf->offset + etr_buf->len - to_copy;

        while (to_copy > 0) {
                /*
                 * In one iteration, we can copy minimum of :
                 *  1) what is available in the source buffer,
                 *  2) what is available in the source buffer, before it
                 *     wraps around.
                 *  3) what is available in the destination page.
                 * in one iteration.
                 */
                if (src_offset >= etr_buf->size)
                        src_offset -= etr_buf->size;
                bytes = tmc_etr_buf_get_data(etr_buf, src_offset, to_copy,
                                             &src_buf);
                if (WARN_ON_ONCE(bytes <= 0))
                        break;
                bytes = min(bytes, (long)(PAGE_SIZE - pg_offset));

                memcpy(dst_pages[pg_idx] + pg_offset, src_buf, bytes);

                to_copy -= bytes;

                /* Move destination pointers */
                pg_offset += bytes;
                if (pg_offset == PAGE_SIZE) {
                        pg_offset = 0;
                        if (++pg_idx == etr_perf->nr_pages)
                                pg_idx = 0;
                }

                /* Move source pointers */
                src_offset += bytes;
        }
}

/*
 * tmc_update_etr_buffer : Update the perf ring buffer with the
 * available trace data. We use software double buffering at the moment.
 *
 * TODO: Add support for reusing the perf ring buffer.
 */
static unsigned long
tmc_update_etr_buffer(struct coresight_device *csdev,
                      struct perf_output_handle *handle,
                      void *config)
{
        bool lost = false;
        unsigned long flags, size = 0;
        struct tmc_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
        struct etr_perf_buffer *etr_perf = config;
        struct etr_buf *etr_buf = etr_perf->etr_buf;

        spin_lock_irqsave(&drvdata->spinlock, flags);

        /* Don't do anything if another tracer is using this sink */
        if (atomic_read(csdev->refcnt) != 1) {
                spin_unlock_irqrestore(&drvdata->spinlock, flags);
                goto out;
        }

        if (WARN_ON(drvdata->perf_buf != etr_buf)) {
                lost = true;
                spin_unlock_irqrestore(&drvdata->spinlock, flags);
                goto out;
        }

        CS_UNLOCK(drvdata->base);

        tmc_flush_and_stop(drvdata);
        tmc_sync_etr_buf(drvdata);

        CS_LOCK(drvdata->base);
        spin_unlock_irqrestore(&drvdata->spinlock, flags);

        size = etr_buf->len;
        if (!etr_perf->snapshot && size > handle->size) {
                size = handle->size;
                lost = true;
        }
        tmc_etr_sync_perf_buffer(etr_perf, size);

        /*
         * In snapshot mode we simply increment the head by the number of byte
         * that were written.  User space function  cs_etm_find_snapshot() will
         * figure out how many bytes to get from the AUX buffer based on the
         * position of the head.
         */
        if (etr_perf->snapshot)
                handle->head += size;

        lost |= etr_buf->full;
out:
        /*
         * Don't set the TRUNCATED flag in snapshot mode because 1) the
         * captured buffer is expected to be truncated and 2) a full buffer
         * prevents the event from being re-enabled by the perf core,
         * resulting in stale data being send to user space.
         */
        if (!etr_perf->snapshot && lost)
                perf_aux_output_flag(handle, PERF_AUX_FLAG_TRUNCATED);
        return size;
}

static int tmc_enable_etr_sink_perf(struct coresight_device *csdev, void *data)
{
        int rc = 0;
        pid_t pid;
        unsigned long flags;
        struct tmc_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
        struct perf_output_handle *handle = data;
        struct etr_perf_buffer *etr_perf = etm_perf_sink_config(handle);

        spin_lock_irqsave(&drvdata->spinlock, flags);
         /* Don't use this sink if it is already claimed by sysFS */
        if (drvdata->mode == CS_MODE_SYSFS) {
                rc = -EBUSY;
                goto unlock_out;
        }

        if (WARN_ON(!etr_perf || !etr_perf->etr_buf)) {
                rc = -EINVAL;
                goto unlock_out;
        }

        /* Get a handle on the pid of the process to monitor */
        pid = etr_perf->pid;

        /* Do not proceed if this device is associated with another session */
        if (drvdata->pid != -1 && drvdata->pid != pid) {
                rc = -EBUSY;
                goto unlock_out;
        }

        etr_perf->head = PERF_IDX2OFF(handle->head, etr_perf);

        /*
         * No HW configuration is needed if the sink is already in
         * use for this session.
         */
        if (drvdata->pid == pid) {
                atomic_inc(csdev->refcnt);
                goto unlock_out;
        }

        rc = tmc_etr_enable_hw(drvdata, etr_perf->etr_buf);
        if (!rc) {
                /* Associate with monitored process. */
                drvdata->pid = pid;
                drvdata->mode = CS_MODE_PERF;
                drvdata->perf_buf = etr_perf->etr_buf;
                atomic_inc(csdev->refcnt);
        }

unlock_out:
        spin_unlock_irqrestore(&drvdata->spinlock, flags);
        return rc;
}

static int tmc_enable_etr_sink(struct coresight_device *csdev,
                               u32 mode, void *data)
{
        switch (mode) {
        case CS_MODE_SYSFS:
                return tmc_enable_etr_sink_sysfs(csdev);
        case CS_MODE_PERF:
                return tmc_enable_etr_sink_perf(csdev, data);
        }

        /* We shouldn't be here */
        return -EINVAL;
}

static int tmc_disable_etr_sink(struct coresight_device *csdev)
{
        unsigned long flags;
        struct tmc_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);

        spin_lock_irqsave(&drvdata->spinlock, flags);

        if (drvdata->reading) {
                spin_unlock_irqrestore(&drvdata->spinlock, flags);
                return -EBUSY;
        }

        if (atomic_dec_return(csdev->refcnt)) {
                spin_unlock_irqrestore(&drvdata->spinlock, flags);
                return -EBUSY;
        }

        /* Complain if we (somehow) got out of sync */
        WARN_ON_ONCE(drvdata->mode == CS_MODE_DISABLED);
        tmc_etr_disable_hw(drvdata);
        /* Dissociate from monitored process. */
        drvdata->pid = -1;
        drvdata->mode = CS_MODE_DISABLED;
        /* Reset perf specific data */
        drvdata->perf_buf = NULL;

        spin_unlock_irqrestore(&drvdata->spinlock, flags);

        dev_dbg(&csdev->dev, "TMC-ETR disabled\n");
        return 0;
}

static const struct coresight_ops_sink tmc_etr_sink_ops = {
        .enable         = tmc_enable_etr_sink,
        .disable        = tmc_disable_etr_sink,
        .alloc_buffer   = tmc_alloc_etr_buffer,
        .update_buffer  = tmc_update_etr_buffer,
        .free_buffer    = tmc_free_etr_buffer,
};

const struct coresight_ops tmc_etr_cs_ops = {
        .sink_ops       = &tmc_etr_sink_ops,
};

int tmc_read_prepare_etr(struct tmc_drvdata *drvdata)
{
        int ret = 0;
        unsigned long flags;

        /* config types are set a boot time and never change */
        if (WARN_ON_ONCE(drvdata->config_type != TMC_CONFIG_TYPE_ETR))
                return -EINVAL;

        spin_lock_irqsave(&drvdata->spinlock, flags);
        if (drvdata->reading) {
                ret = -EBUSY;
                goto out;
        }

        /*
         * We can safely allow reads even if the ETR is operating in PERF mode,
         * since the sysfs session is captured in mode specific data.
         * If drvdata::sysfs_data is NULL the trace data has been read already.
         */
        if (!drvdata->sysfs_buf) {
                ret = -EINVAL;
                goto out;
        }

        /* Disable the TMC if we are trying to read from a running session. */
        if (drvdata->mode == CS_MODE_SYSFS)
                __tmc_etr_disable_hw(drvdata);

        drvdata->reading = true;
out:
        spin_unlock_irqrestore(&drvdata->spinlock, flags);

        return ret;
}

int tmc_read_unprepare_etr(struct tmc_drvdata *drvdata)
{
        unsigned long flags;
        struct etr_buf *sysfs_buf = NULL;

        /* config types are set a boot time and never change */
        if (WARN_ON_ONCE(drvdata->config_type != TMC_CONFIG_TYPE_ETR))
                return -EINVAL;

        spin_lock_irqsave(&drvdata->spinlock, flags);

        /* RE-enable the TMC if need be */
        if (drvdata->mode == CS_MODE_SYSFS) {
                /*
                 * The trace run will continue with the same allocated trace
                 * buffer. Since the tracer is still enabled drvdata::buf can't
                 * be NULL.
                 */
                __tmc_etr_enable_hw(drvdata);
        } else {
                /*
                 * The ETR is not tracing and the buffer was just read.
                 * As such prepare to free the trace buffer.
                 */
                sysfs_buf = drvdata->sysfs_buf;
                drvdata->sysfs_buf = NULL;
        }

        drvdata->reading = false;
        spin_unlock_irqrestore(&drvdata->spinlock, flags);

        /* Free allocated memory out side of the spinlock */
        if (sysfs_buf)
                tmc_etr_free_sysfs_buf(sysfs_buf);

        return 0;
}