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/mutex.h>
  13 #include <linux/of.h>
  14 #include <linux/of_address.h>
  15 #include <linux/slab.h>
  16
  17 #include "common.h"
  18
  19 /**
  20  * struct scmi_smc - Structure representing a SCMI smc transport
  21  *
  22  * @cinfo: SCMI channel info
  23  * @shmem: Transmit/Receive shared memory area
  24  * @shmem_lock: Lock to protect access to Tx/Rx shared memory area
  25  * @func_id: smc/hvc call function id
  26  */
  27
  28 struct scmi_smc {
  29         struct scmi_chan_info *cinfo;
  30         struct scmi_shared_mem __iomem *shmem;
  31         struct mutex shmem_lock;
  32         u32 func_id;
  33 };
  34
  35 static bool smc_chan_available(struct device *dev, int idx)
  36 {
  37         struct device_node *np = of_parse_phandle(dev->of_node, "shmem", 0);
  38         if (!np)
  39                 return false;
  40
  41         of_node_put(np);
  42         return true;
  43 }
  44
  45 static int smc_chan_setup(struct scmi_chan_info *cinfo, struct device *dev,
  46                           bool tx)
  47 {
  48         struct device *cdev = cinfo->dev;
  49         struct scmi_smc *scmi_info;
  50         resource_size_t size;
  51         struct resource res;
  52         struct device_node *np;
  53         u32 func_id;
  54         int ret;
  55
  56         if (!tx)
  57                 return -ENODEV;
  58
  59         scmi_info = devm_kzalloc(dev, sizeof(*scmi_info), GFP_KERNEL);
  60         if (!scmi_info)
  61                 return -ENOMEM;
  62
  63         np = of_parse_phandle(cdev->of_node, "shmem", 0);
  64         ret = of_address_to_resource(np, 0, &res);
  65         of_node_put(np);
  66         if (ret) {
  67                 dev_err(cdev, "failed to get SCMI Tx shared memory\n");
  68                 return ret;
  69         }
  70
  71         size = resource_size(&res);
  72         scmi_info->shmem = devm_ioremap(dev, res.start, size);
  73         if (!scmi_info->shmem) {
  74                 dev_err(dev, "failed to ioremap SCMI Tx shared memory\n");
  75                 return -EADDRNOTAVAIL;
  76         }
  77
  78         ret = of_property_read_u32(dev->of_node, "arm,smc-id", &func_id);
  79         if (ret < 0)
  80                 return ret;
  81
  82         scmi_info->func_id = func_id;
  83         scmi_info->cinfo = cinfo;
  84         mutex_init(&scmi_info->shmem_lock);
  85         cinfo->transport_info = scmi_info;
  86
  87         return 0;
  88 }
  89
  90 static int smc_chan_free(int id, void *p, void *data)
  91 {
  92         struct scmi_chan_info *cinfo = p;
  93         struct scmi_smc *scmi_info = cinfo->transport_info;
  94
  95         cinfo->transport_info = NULL;
  96         scmi_info->cinfo = NULL;
  97
  98         scmi_free_channel(cinfo, data, id);
  99
 100         return 0;
 101 }
 102
 103 static int smc_send_message(struct scmi_chan_info *cinfo,
 104                             struct scmi_xfer *xfer)
 105 {
 106         struct scmi_smc *scmi_info = cinfo->transport_info;
 107         struct arm_smccc_res res;
 108
 109         mutex_lock(&scmi_info->shmem_lock);
 110
 111         shmem_tx_prepare(scmi_info->shmem, xfer);
 112
 113         arm_smccc_1_1_invoke(scmi_info->func_id, 0, 0, 0, 0, 0, 0, 0, &res);
 114         scmi_rx_callback(scmi_info->cinfo, shmem_read_header(scmi_info->shmem));
 115
 116         mutex_unlock(&scmi_info->shmem_lock);
 117
 118         /* Only SMCCC_RET_NOT_SUPPORTED is valid error code */
 119         if (res.a0)
 120                 return -EOPNOTSUPP;
 121         return 0;
 122 }
 123
 124 static void smc_fetch_response(struct scmi_chan_info *cinfo,
 125                                struct scmi_xfer *xfer)
 126 {
 127         struct scmi_smc *scmi_info = cinfo->transport_info;
 128
 129         shmem_fetch_response(scmi_info->shmem, xfer);
 130 }
 131
 132 static bool
 133 smc_poll_done(struct scmi_chan_info *cinfo, struct scmi_xfer *xfer)
 134 {
 135         struct scmi_smc *scmi_info = cinfo->transport_info;
 136
 137         return shmem_poll_done(scmi_info->shmem, xfer);
 138 }
 139
 140 static const struct scmi_transport_ops scmi_smc_ops = {
 141         .chan_available = smc_chan_available,
 142         .chan_setup = smc_chan_setup,
 143         .chan_free = smc_chan_free,
 144         .send_message = smc_send_message,
 145         .fetch_response = smc_fetch_response,
 146         .poll_done = smc_poll_done,
 147 };
 148
 149 const struct scmi_desc scmi_smc_desc = {
 150         .ops = &scmi_smc_ops,
 151         .max_rx_timeout_ms = 30,
 152         .max_msg = 20,
 153         .max_msg_size = 128,
 154 };