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  * The shmem address is split into 4K page and offset.
  25  * This is to make sure the parameters fit in 32bit arguments of the
  26  * smc/hvc call to keep it uniform across smc32/smc64 conventions.
  27  * This however limits the shmem address to 44 bit.
  28  *
  29  * These optional parameters can be used to distinguish among multiple
  30  * scmi instances that are using the same smc-id.
  31  * The page parameter is passed in r1/x1/w1 register and the offset parameter
  32  * is passed in r2/x2/w2 register.
  33  */
  34
  35 #define SHMEM_SIZE (SZ_4K)
  36 #define SHMEM_SHIFT 12
  37 #define SHMEM_PAGE(x) (_UL((x) >> SHMEM_SHIFT))
  38 #define SHMEM_OFFSET(x) ((x) & (SHMEM_SIZE - 1))
  39
  40 /**
  41  * struct scmi_smc - Structure representing a SCMI smc transport
  42  *
  43  * @cinfo: SCMI channel info
  44  * @shmem: Transmit/Receive shared memory area
  45  * @shmem_lock: Lock to protect access to Tx/Rx shared memory area.
  46  *              Used when NOT operating in atomic mode.
  47  * @inflight: Atomic flag to protect access to Tx/Rx shared memory area.
  48  *            Used when operating in atomic mode.
  49  * @func_id: smc/hvc call function id
  50  * @param_page: 4K page number of the shmem channel
  51  * @param_offset: Offset within the 4K page of the shmem channel
  52  */
  53
  54 struct scmi_smc {
  55         struct scmi_chan_info *cinfo;
  56         struct scmi_shared_mem __iomem *shmem;
  57         /* Protect access to shmem area */
  58         struct mutex shmem_lock;
  59 #define INFLIGHT_NONE   MSG_TOKEN_MAX
  60         atomic_t inflight;
  61         u32 func_id;
  62         u32 param_page;
  63         u32 param_offset;
  64 };
  65
  66 static irqreturn_t smc_msg_done_isr(int irq, void *data)
  67 {
  68         struct scmi_smc *scmi_info = data;
  69
  70         scmi_rx_callback(scmi_info->cinfo,
  71                          shmem_read_header(scmi_info->shmem), NULL);
  72
  73         return IRQ_HANDLED;
  74 }
  75
  76 static bool smc_chan_available(struct device_node *of_node, int idx)
  77 {
  78         struct device_node *np = of_parse_phandle(of_node, "shmem", 0);
  79         if (!np)
  80                 return false;
  81
  82         of_node_put(np);
  83         return true;
  84 }
  85
  86 static inline void smc_channel_lock_init(struct scmi_smc *scmi_info)
  87 {
  88         if (IS_ENABLED(CONFIG_ARM_SCMI_TRANSPORT_SMC_ATOMIC_ENABLE))
  89                 atomic_set(&scmi_info->inflight, INFLIGHT_NONE);
  90         else
  91                 mutex_init(&scmi_info->shmem_lock);
  92 }
  93
  94 static bool smc_xfer_inflight(struct scmi_xfer *xfer, atomic_t *inflight)
  95 {
  96         int ret;
  97
  98         ret = atomic_cmpxchg(inflight, INFLIGHT_NONE, xfer->hdr.seq);
  99
 100         return ret == INFLIGHT_NONE;
 101 }
 102
 103 static inline void
 104 smc_channel_lock_acquire(struct scmi_smc *scmi_info,
 105                          struct scmi_xfer *xfer __maybe_unused)
 106 {
 107         if (IS_ENABLED(CONFIG_ARM_SCMI_TRANSPORT_SMC_ATOMIC_ENABLE))
 108                 spin_until_cond(smc_xfer_inflight(xfer, &scmi_info->inflight));
 109         else
 110                 mutex_lock(&scmi_info->shmem_lock);
 111 }
 112
 113 static inline void smc_channel_lock_release(struct scmi_smc *scmi_info)
 114 {
 115         if (IS_ENABLED(CONFIG_ARM_SCMI_TRANSPORT_SMC_ATOMIC_ENABLE))
 116                 atomic_set(&scmi_info->inflight, INFLIGHT_NONE);
 117         else
 118                 mutex_unlock(&scmi_info->shmem_lock);
 119 }
 120
 121 static int smc_chan_setup(struct scmi_chan_info *cinfo, struct device *dev,
 122                           bool tx)
 123 {
 124         struct device *cdev = cinfo->dev;
 125         struct scmi_smc *scmi_info;
 126         resource_size_t size;
 127         struct resource res;
 128         struct device_node *np;
 129         u32 func_id;
 130         int ret, irq;
 131
 132         if (!tx)
 133                 return -ENODEV;
 134
 135         scmi_info = devm_kzalloc(dev, sizeof(*scmi_info), GFP_KERNEL);
 136         if (!scmi_info)
 137                 return -ENOMEM;
 138
 139         np = of_parse_phandle(cdev->of_node, "shmem", 0);
 140         if (!of_device_is_compatible(np, "arm,scmi-shmem"))
 141                 return -ENXIO;
 142
 143         ret = of_address_to_resource(np, 0, &res);
 144         of_node_put(np);
 145         if (ret) {
 146                 dev_err(cdev, "failed to get SCMI Tx shared memory\n");
 147                 return ret;
 148         }
 149
 150         size = resource_size(&res);
 151         scmi_info->shmem = devm_ioremap(dev, res.start, size);
 152         if (!scmi_info->shmem) {
 153                 dev_err(dev, "failed to ioremap SCMI Tx shared memory\n");
 154                 return -EADDRNOTAVAIL;
 155         }
 156
 157         ret = of_property_read_u32(dev->of_node, "arm,smc-id", &func_id);
 158         if (ret < 0)
 159                 return ret;
 160
 161         if (of_device_is_compatible(dev->of_node, "arm,scmi-smc-param")) {
 162                 scmi_info->param_page = SHMEM_PAGE(res.start);
 163                 scmi_info->param_offset = SHMEM_OFFSET(res.start);
 164         }
 165         /*
 166          * If there is an interrupt named "a2p", then the service and
 167          * completion of a message is signaled by an interrupt rather than by
 168          * the return of the SMC call.
 169          */
 170         irq = of_irq_get_byname(cdev->of_node, "a2p");
 171         if (irq > 0) {
 172                 ret = devm_request_irq(dev, irq, smc_msg_done_isr,
 173                                        IRQF_NO_SUSPEND,
 174                                        dev_name(dev), scmi_info);
 175                 if (ret) {
 176                         dev_err(dev, "failed to setup SCMI smc irq\n");
 177                         return ret;
 178                 }
 179         } else {
 180                 cinfo->no_completion_irq = true;
 181         }
 182
 183         scmi_info->func_id = func_id;
 184         scmi_info->cinfo = cinfo;
 185         smc_channel_lock_init(scmi_info);
 186         cinfo->transport_info = scmi_info;
 187
 188         return 0;
 189 }
 190
 191 static int smc_chan_free(int id, void *p, void *data)
 192 {
 193         struct scmi_chan_info *cinfo = p;
 194         struct scmi_smc *scmi_info = cinfo->transport_info;
 195
 196         cinfo->transport_info = NULL;
 197         scmi_info->cinfo = NULL;
 198
 199         return 0;
 200 }
 201
 202 static int smc_send_message(struct scmi_chan_info *cinfo,
 203                             struct scmi_xfer *xfer)
 204 {
 205         struct scmi_smc *scmi_info = cinfo->transport_info;
 206         struct arm_smccc_res res;
 207         unsigned long page = scmi_info->param_page;
 208         unsigned long offset = scmi_info->param_offset;
 209
 210         /*
 211          * Channel will be released only once response has been
 212          * surely fully retrieved, so after .mark_txdone()
 213          */
 214         smc_channel_lock_acquire(scmi_info, xfer);
 215
 216         shmem_tx_prepare(scmi_info->shmem, xfer, cinfo);
 217
 218         arm_smccc_1_1_invoke(scmi_info->func_id, page, offset, 0, 0, 0, 0, 0,
 219                              &res);
 220
 221         /* Only SMCCC_RET_NOT_SUPPORTED is valid error code */
 222         if (res.a0) {
 223                 smc_channel_lock_release(scmi_info);
 224                 return -EOPNOTSUPP;
 225         }
 226
 227         return 0;
 228 }
 229
 230 static void smc_fetch_response(struct scmi_chan_info *cinfo,
 231                                struct scmi_xfer *xfer)
 232 {
 233         struct scmi_smc *scmi_info = cinfo->transport_info;
 234
 235         shmem_fetch_response(scmi_info->shmem, xfer);
 236 }
 237
 238 static void smc_mark_txdone(struct scmi_chan_info *cinfo, int ret,
 239                             struct scmi_xfer *__unused)
 240 {
 241         struct scmi_smc *scmi_info = cinfo->transport_info;
 242
 243         smc_channel_lock_release(scmi_info);
 244 }
 245
 246 static const struct scmi_transport_ops scmi_smc_ops = {
 247         .chan_available = smc_chan_available,
 248         .chan_setup = smc_chan_setup,
 249         .chan_free = smc_chan_free,
 250         .send_message = smc_send_message,
 251         .mark_txdone = smc_mark_txdone,
 252         .fetch_response = smc_fetch_response,
 253 };
 254
 255 const struct scmi_desc scmi_smc_desc = {
 256         .ops = &scmi_smc_ops,
 257         .max_rx_timeout_ms = 30,
 258         .max_msg = 20,
 259         .max_msg_size = 128,
 260         /*
 261          * Setting .sync_cmds_atomic_replies to true for SMC assumes that,
 262          * once the SMC instruction has completed successfully, the issued
 263          * SCMI command would have been already fully processed by the SCMI
 264          * platform firmware and so any possible response value expected
 265          * for the issued command will be immmediately ready to be fetched
 266          * from the shared memory area.
 267          */
 268         .sync_cmds_completed_on_ret = true,
 269         .atomic_enabled = IS_ENABLED(CONFIG_ARM_SCMI_TRANSPORT_SMC_ATOMIC_ENABLE),
 270 };