linux/drivers/firmware/arm_scmi/smc.c
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   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
  32struct 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
  41static 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
  50static 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
  60static 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
 123static 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
 136static 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
 164static 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
 172static bool
 173smc_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
 180static 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
 189const 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};
 195