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/atomic.h>
  11 #include <linux/device.h>
  12 #include <linux/err.h>
  13 #include <linux/interrupt.h>
  14 #include <linux/mutex.h>
  15 #include <linux/of.h>
  16 #include <linux/of_address.h>
  17 #include <linux/of_irq.h>
  18 #include <linux/processor.h>
  19 #include <linux/slab.h>
  20
  21 #include "common.h"
  22
  23 /**
  24  * struct scmi_smc - Structure representing a SCMI smc transport
  25  *
  26  * @cinfo: SCMI channel info
  27  * @shmem: Transmit/Receive shared memory area
  28  * @shmem_lock: Lock to protect access to Tx/Rx shared memory area.
  29  *              Used when NOT operating in atomic mode.
  30  * @inflight: Atomic flag to protect access to Tx/Rx shared memory area.
  31  *            Used when operating in atomic mode.
  32  * @func_id: smc/hvc call function id
  33  */
  34
  35 struct scmi_smc {
  36         struct scmi_chan_info *cinfo;
  37         struct scmi_shared_mem __iomem *shmem;
  38         /* Protect access to shmem area */
  39         struct mutex shmem_lock;
  40 #define INFLIGHT_NONE   MSG_TOKEN_MAX
  41         atomic_t inflight;
  42         u32 func_id;
  43 };
  44
  45 static irqreturn_t smc_msg_done_isr(int irq, void *data)
  46 {
  47         struct scmi_smc *scmi_info = data;
  48
  49         scmi_rx_callback(scmi_info->cinfo,
  50                          shmem_read_header(scmi_info->shmem), NULL);
  51
  52         return IRQ_HANDLED;
  53 }
  54
  55 static bool smc_chan_available(struct device *dev, int idx)
  56 {
  57         struct device_node *np = of_parse_phandle(dev->of_node, "shmem", 0);
  58         if (!np)
  59                 return false;
  60
  61         of_node_put(np);
  62         return true;
  63 }
  64
  65 static inline void smc_channel_lock_init(struct scmi_smc *scmi_info)
  66 {
  67         if (IS_ENABLED(CONFIG_ARM_SCMI_TRANSPORT_SMC_ATOMIC_ENABLE))
  68                 atomic_set(&scmi_info->inflight, INFLIGHT_NONE);
  69         else
  70                 mutex_init(&scmi_info->shmem_lock);
  71 }
  72
  73 static bool smc_xfer_inflight(struct scmi_xfer *xfer, atomic_t *inflight)
  74 {
  75         int ret;
  76
  77         ret = atomic_cmpxchg(inflight, INFLIGHT_NONE, xfer->hdr.seq);
  78
  79         return ret == INFLIGHT_NONE;
  80 }
  81
  82 static inline void
  83 smc_channel_lock_acquire(struct scmi_smc *scmi_info,
  84                          struct scmi_xfer *xfer __maybe_unused)
  85 {
  86         if (IS_ENABLED(CONFIG_ARM_SCMI_TRANSPORT_SMC_ATOMIC_ENABLE))
  87                 spin_until_cond(smc_xfer_inflight(xfer, &scmi_info->inflight));
  88         else
  89                 mutex_lock(&scmi_info->shmem_lock);
  90 }
  91
  92 static inline void smc_channel_lock_release(struct scmi_smc *scmi_info)
  93 {
  94         if (IS_ENABLED(CONFIG_ARM_SCMI_TRANSPORT_SMC_ATOMIC_ENABLE))
  95                 atomic_set(&scmi_info->inflight, INFLIGHT_NONE);
  96         else
  97                 mutex_unlock(&scmi_info->shmem_lock);
  98 }
  99
 100 static int smc_chan_setup(struct scmi_chan_info *cinfo, struct device *dev,
 101                           bool tx)
 102 {
 103         struct device *cdev = cinfo->dev;
 104         struct scmi_smc *scmi_info;
 105         resource_size_t size;
 106         struct resource res;
 107         struct device_node *np;
 108         u32 func_id;
 109         int ret, irq;
 110
 111         if (!tx)
 112                 return -ENODEV;
 113
 114         scmi_info = devm_kzalloc(dev, sizeof(*scmi_info), GFP_KERNEL);
 115         if (!scmi_info)
 116                 return -ENOMEM;
 117
 118         np = of_parse_phandle(cdev->of_node, "shmem", 0);
 119         if (!of_device_is_compatible(np, "arm,scmi-shmem"))
 120                 return -ENXIO;
 121
 122         ret = of_address_to_resource(np, 0, &res);
 123         of_node_put(np);
 124         if (ret) {
 125                 dev_err(cdev, "failed to get SCMI Tx shared memory\n");
 126                 return ret;
 127         }
 128
 129         size = resource_size(&res);
 130         scmi_info->shmem = devm_ioremap(dev, res.start, size);
 131         if (!scmi_info->shmem) {
 132                 dev_err(dev, "failed to ioremap SCMI Tx shared memory\n");
 133                 return -EADDRNOTAVAIL;
 134         }
 135
 136         ret = of_property_read_u32(dev->of_node, "arm,smc-id", &func_id);
 137         if (ret < 0)
 138                 return ret;
 139
 140         /*
 141          * If there is an interrupt named "a2p", then the service and
 142          * completion of a message is signaled by an interrupt rather than by
 143          * the return of the SMC call.
 144          */
 145         irq = of_irq_get_byname(cdev->of_node, "a2p");
 146         if (irq > 0) {
 147                 ret = devm_request_irq(dev, irq, smc_msg_done_isr,
 148                                        IRQF_NO_SUSPEND,
 149                                        dev_name(dev), scmi_info);
 150                 if (ret) {
 151                         dev_err(dev, "failed to setup SCMI smc irq\n");
 152                         return ret;
 153                 }
 154         } else {
 155                 cinfo->no_completion_irq = true;
 156         }
 157
 158         scmi_info->func_id = func_id;
 159         scmi_info->cinfo = cinfo;
 160         smc_channel_lock_init(scmi_info);
 161         cinfo->transport_info = scmi_info;
 162
 163         return 0;
 164 }
 165
 166 static int smc_chan_free(int id, void *p, void *data)
 167 {
 168         struct scmi_chan_info *cinfo = p;
 169         struct scmi_smc *scmi_info = cinfo->transport_info;
 170
 171         cinfo->transport_info = NULL;
 172         scmi_info->cinfo = NULL;
 173
 174         scmi_free_channel(cinfo, data, id);
 175
 176         return 0;
 177 }
 178
 179 static int smc_send_message(struct scmi_chan_info *cinfo,
 180                             struct scmi_xfer *xfer)
 181 {
 182         struct scmi_smc *scmi_info = cinfo->transport_info;
 183         struct arm_smccc_res res;
 184
 185         /*
 186          * Channel will be released only once response has been
 187          * surely fully retrieved, so after .mark_txdone()
 188          */
 189         smc_channel_lock_acquire(scmi_info, xfer);
 190
 191         shmem_tx_prepare(scmi_info->shmem, xfer);
 192
 193         arm_smccc_1_1_invoke(scmi_info->func_id, 0, 0, 0, 0, 0, 0, 0, &res);
 194
 195         /* Only SMCCC_RET_NOT_SUPPORTED is valid error code */
 196         if (res.a0) {
 197                 smc_channel_lock_release(scmi_info);
 198                 return -EOPNOTSUPP;
 199         }
 200
 201         return 0;
 202 }
 203
 204 static void smc_fetch_response(struct scmi_chan_info *cinfo,
 205                                struct scmi_xfer *xfer)
 206 {
 207         struct scmi_smc *scmi_info = cinfo->transport_info;
 208
 209         shmem_fetch_response(scmi_info->shmem, xfer);
 210 }
 211
 212 static void smc_mark_txdone(struct scmi_chan_info *cinfo, int ret,
 213                             struct scmi_xfer *__unused)
 214 {
 215         struct scmi_smc *scmi_info = cinfo->transport_info;
 216
 217         smc_channel_lock_release(scmi_info);
 218 }
 219
 220 static const struct scmi_transport_ops scmi_smc_ops = {
 221         .chan_available = smc_chan_available,
 222         .chan_setup = smc_chan_setup,
 223         .chan_free = smc_chan_free,
 224         .send_message = smc_send_message,
 225         .mark_txdone = smc_mark_txdone,
 226         .fetch_response = smc_fetch_response,
 227 };
 228
 229 const struct scmi_desc scmi_smc_desc = {
 230         .ops = &scmi_smc_ops,
 231         .max_rx_timeout_ms = 30,
 232         .max_msg = 20,
 233         .max_msg_size = 128,
 234         /*
 235          * Setting .sync_cmds_atomic_replies to true for SMC assumes that,
 236          * once the SMC instruction has completed successfully, the issued
 237          * SCMI command would have been already fully processed by the SCMI
 238          * platform firmware and so any possible response value expected
 239          * for the issued command will be immmediately ready to be fetched
 240          * from the shared memory area.
 241          */
 242         .sync_cmds_completed_on_ret = true,
 243         .atomic_enabled = IS_ENABLED(CONFIG_ARM_SCMI_TRANSPORT_SMC_ATOMIC_ENABLE),
 244 };