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         ret = of_address_to_resource(np, 0, &res);
  80         of_node_put(np);
  81         if (ret) {
  82                 dev_err(cdev, "failed to get SCMI Tx shared memory\n");
  83                 return ret;
  84         }
  85
  86         size = resource_size(&res);
  87         scmi_info->shmem = devm_ioremap(dev, res.start, size);
  88         if (!scmi_info->shmem) {
  89                 dev_err(dev, "failed to ioremap SCMI Tx shared memory\n");
  90                 return -EADDRNOTAVAIL;
  91         }
  92
  93         ret = of_property_read_u32(dev->of_node, "arm,smc-id", &func_id);
  94         if (ret < 0)
  95                 return ret;
  96
  97         /*
  98          * If there is an interrupt named "a2p", then the service and
  99          * completion of a message is signaled by an interrupt rather than by
 100          * the return of the SMC call.
 101          */
 102         irq = of_irq_get_byname(cdev->of_node, "a2p");
 103         if (irq > 0) {
 104                 ret = devm_request_irq(dev, irq, smc_msg_done_isr,
 105                                        IRQF_NO_SUSPEND,
 106                                        dev_name(dev), scmi_info);
 107                 if (ret) {
 108                         dev_err(dev, "failed to setup SCMI smc irq\n");
 109                         return ret;
 110                 }
 111                 init_completion(&scmi_info->tx_complete);
 112                 scmi_info->irq = irq;
 113         }
 114
 115         scmi_info->func_id = func_id;
 116         scmi_info->cinfo = cinfo;
 117         mutex_init(&scmi_info->shmem_lock);
 118         cinfo->transport_info = scmi_info;
 119
 120         return 0;
 121 }
 122
 123 static int smc_chan_free(int id, void *p, void *data)
 124 {
 125         struct scmi_chan_info *cinfo = p;
 126         struct scmi_smc *scmi_info = cinfo->transport_info;
 127
 128         cinfo->transport_info = NULL;
 129         scmi_info->cinfo = NULL;
 130
 131         scmi_free_channel(cinfo, data, id);
 132
 133         return 0;
 134 }
 135
 136 static int smc_send_message(struct scmi_chan_info *cinfo,
 137                             struct scmi_xfer *xfer)
 138 {
 139         struct scmi_smc *scmi_info = cinfo->transport_info;
 140         struct arm_smccc_res res;
 141
 142         mutex_lock(&scmi_info->shmem_lock);
 143
 144         shmem_tx_prepare(scmi_info->shmem, xfer);
 145
 146         if (scmi_info->irq)
 147                 reinit_completion(&scmi_info->tx_complete);
 148
 149         arm_smccc_1_1_invoke(scmi_info->func_id, 0, 0, 0, 0, 0, 0, 0, &res);
 150
 151         if (scmi_info->irq)
 152                 wait_for_completion(&scmi_info->tx_complete);
 153
 154         scmi_rx_callback(scmi_info->cinfo, shmem_read_header(scmi_info->shmem));
 155
 156         mutex_unlock(&scmi_info->shmem_lock);
 157
 158         /* Only SMCCC_RET_NOT_SUPPORTED is valid error code */
 159         if (res.a0)
 160                 return -EOPNOTSUPP;
 161         return 0;
 162 }
 163
 164 static void smc_fetch_response(struct scmi_chan_info *cinfo,
 165                                struct scmi_xfer *xfer)
 166 {
 167         struct scmi_smc *scmi_info = cinfo->transport_info;
 168
 169         shmem_fetch_response(scmi_info->shmem, xfer);
 170 }
 171
 172 static bool
 173 smc_poll_done(struct scmi_chan_info *cinfo, struct scmi_xfer *xfer)
 174 {
 175         struct scmi_smc *scmi_info = cinfo->transport_info;
 176
 177         return shmem_poll_done(scmi_info->shmem, xfer);
 178 }
 179
 180 static const struct scmi_transport_ops scmi_smc_ops = {
 181         .chan_available = smc_chan_available,
 182         .chan_setup = smc_chan_setup,
 183         .chan_free = smc_chan_free,
 184         .send_message = smc_send_message,
 185         .fetch_response = smc_fetch_response,
 186         .poll_done = smc_poll_done,
 187 };
 188
 189 const struct scmi_desc scmi_smc_desc = {
 190         .ops = &scmi_smc_ops,
 191         .max_rx_timeout_ms = 30,
 192         .max_msg = 20,
 193         .max_msg_size = 128,
 194 };