drivers/firmware/arm_scmi/smc.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * System Control and Management Interface (SCMI) Message SMC/HVC
   4  * Transport driver
   5  *
   6  * Copyright 2020 NXP
   7  */
   8
   9 #include <linux/arm-smccc.h>
  10 #include <linux/device.h>
  11 #include <linux/err.h>
  12 #include <linux/interrupt.h>
  13 #include <linux/mutex.h>
  14 #include <linux/of.h>
  15 #include <linux/of_address.h>
  16 #include <linux/of_irq.h>
  17 #include <linux/slab.h>
  18
  19 #include "common.h"
  20
  21 /**
  22  * struct scmi_smc - Structure representing a SCMI smc transport
  23  *
  24  * @cinfo: SCMI channel info
  25  * @shmem: Transmit/Receive shared memory area
  26  * @shmem_lock: Lock to protect access to Tx/Rx shared memory area
  27  * @func_id: smc/hvc call function id
  28  * @irq: Optional; employed when platforms indicates msg completion by intr.
  29  * @tx_complete: Optional, employed only when irq is valid.
  30  */
  31
  32 struct scmi_smc {
  33         struct scmi_chan_info *cinfo;
  34         struct scmi_shared_mem __iomem *shmem;
  35         struct mutex shmem_lock;
  36         u32 func_id;
  37         int irq;
  38         struct completion tx_complete;
  39 };
  40
  41 static irqreturn_t smc_msg_done_isr(int irq, void *data)
  42 {
  43         struct scmi_smc *scmi_info = data;
  44
  45         complete(&scmi_info->tx_complete);
  46
  47         return IRQ_HANDLED;
  48 }
  49
  50 static bool smc_chan_available(struct device *dev, int idx)
  51 {
  52         struct device_node *np = of_parse_phandle(dev->of_node, "shmem", 0);
  53         if (!np)
  54                 return false;
  55
  56         of_node_put(np);
  57         return true;
  58 }
  59
  60 static int smc_chan_setup(struct scmi_chan_info *cinfo, struct device *dev,
  61                           bool tx)
  62 {
  63         struct device *cdev = cinfo->dev;
  64         struct scmi_smc *scmi_info;
  65         resource_size_t size;
  66         struct resource res;
  67         struct device_node *np;
  68         u32 func_id;
  69         int ret, irq;
  70
  71         if (!tx)
  72                 return -ENODEV;
  73
  74         scmi_info = devm_kzalloc(dev, sizeof(*scmi_info), GFP_KERNEL);
  75         if (!scmi_info)
  76                 return -ENOMEM;
  77
  78         np = of_parse_phandle(cdev->of_node, "shmem", 0);
  79         if (!of_device_is_compatible(np, "arm,scmi-shmem"))
  80                 return -ENXIO;
  81
  82         ret = of_address_to_resource(np, 0, &res);
  83         of_node_put(np);
  84         if (ret) {
  85                 dev_err(cdev, "failed to get SCMI Tx shared memory\n");
  86                 return ret;
  87         }
  88
  89         size = resource_size(&res);
  90         scmi_info->shmem = devm_ioremap(dev, res.start, size);
  91         if (!scmi_info->shmem) {
  92                 dev_err(dev, "failed to ioremap SCMI Tx shared memory\n");
  93                 return -EADDRNOTAVAIL;
  94         }
  95
  96         ret = of_property_read_u32(dev->of_node, "arm,smc-id", &func_id);
  97         if (ret < 0)
  98                 return ret;
  99
 100         /*
 101          * If there is an interrupt named "a2p", then the service and
 102          * completion of a message is signaled by an interrupt rather than by
 103          * the return of the SMC call.
 104          */
 105         irq = of_irq_get_byname(cdev->of_node, "a2p");
 106         if (irq > 0) {
 107                 ret = devm_request_irq(dev, irq, smc_msg_done_isr,
 108                                        IRQF_NO_SUSPEND,
 109                                        dev_name(dev), scmi_info);
 110                 if (ret) {
 111                         dev_err(dev, "failed to setup SCMI smc irq\n");
 112                         return ret;
 113                 }
 114                 init_completion(&scmi_info->tx_complete);
 115                 scmi_info->irq = irq;
 116         }
 117
 118         scmi_info->func_id = func_id;
 119         scmi_info->cinfo = cinfo;
 120         mutex_init(&scmi_info->shmem_lock);
 121         cinfo->transport_info = scmi_info;
 122
 123         return 0;
 124 }
 125
 126 static int smc_chan_free(int id, void *p, void *data)
 127 {
 128         struct scmi_chan_info *cinfo = p;
 129         struct scmi_smc *scmi_info = cinfo->transport_info;
 130
 131         cinfo->transport_info = NULL;
 132         scmi_info->cinfo = NULL;
 133
 134         scmi_free_channel(cinfo, data, id);
 135
 136         return 0;
 137 }
 138
 139 static int smc_send_message(struct scmi_chan_info *cinfo,
 140                             struct scmi_xfer *xfer)
 141 {
 142         struct scmi_smc *scmi_info = cinfo->transport_info;
 143         struct arm_smccc_res res;
 144
 145         mutex_lock(&scmi_info->shmem_lock);
 146
 147         shmem_tx_prepare(scmi_info->shmem, xfer);
 148
 149         if (scmi_info->irq)
 150                 reinit_completion(&scmi_info->tx_complete);
 151
 152         arm_smccc_1_1_invoke(scmi_info->func_id, 0, 0, 0, 0, 0, 0, 0, &res);
 153
 154         if (scmi_info->irq)
 155                 wait_for_completion(&scmi_info->tx_complete);
 156
 157         scmi_rx_callback(scmi_info->cinfo,
 158                          shmem_read_header(scmi_info->shmem), NULL);
 159
 160         mutex_unlock(&scmi_info->shmem_lock);
 161
 162         /* Only SMCCC_RET_NOT_SUPPORTED is valid error code */
 163         if (res.a0)
 164                 return -EOPNOTSUPP;
 165         return 0;
 166 }
 167
 168 static void smc_fetch_response(struct scmi_chan_info *cinfo,
 169                                struct scmi_xfer *xfer)
 170 {
 171         struct scmi_smc *scmi_info = cinfo->transport_info;
 172
 173         shmem_fetch_response(scmi_info->shmem, xfer);
 174 }
 175
 176 static bool
 177 smc_poll_done(struct scmi_chan_info *cinfo, struct scmi_xfer *xfer)
 178 {
 179         struct scmi_smc *scmi_info = cinfo->transport_info;
 180
 181         return shmem_poll_done(scmi_info->shmem, xfer);
 182 }
 183
 184 static const struct scmi_transport_ops scmi_smc_ops = {
 185         .chan_available = smc_chan_available,
 186         .chan_setup = smc_chan_setup,
 187         .chan_free = smc_chan_free,
 188         .send_message = smc_send_message,
 189         .fetch_response = smc_fetch_response,
 190         .poll_done = smc_poll_done,
 191 };
 192
 193 const struct scmi_desc scmi_smc_desc = {
 194         .ops = &scmi_smc_ops,
 195         .max_rx_timeout_ms = 30,
 196         .max_msg = 20,
 197         .max_msg_size = 128,
 198 };