drivers/firmware/qcom_scm-legacy.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /* Copyright (c) 2010,2015,2019 The Linux Foundation. All rights reserved.
   3  * Copyright (C) 2015 Linaro Ltd.
   4  */
   5
   6 #include <linux/slab.h>
   7 #include <linux/io.h>
   8 #include <linux/module.h>
   9 #include <linux/mutex.h>
  10 #include <linux/errno.h>
  11 #include <linux/err.h>
  12 #include <linux/qcom_scm.h>
  13 #include <linux/arm-smccc.h>
  14 #include <linux/dma-mapping.h>
  15
  16 #include "qcom_scm.h"
  17
  18 static DEFINE_MUTEX(qcom_scm_lock);
  19
  20
  21 /**
  22  * struct arm_smccc_args
  23  * @args:       The array of values used in registers in smc instruction
  24  */
  25 struct arm_smccc_args {
  26         unsigned long args[8];
  27 };
  28
  29
  30 /**
  31  * struct scm_legacy_command - one SCM command buffer
  32  * @len: total available memory for command and response
  33  * @buf_offset: start of command buffer
  34  * @resp_hdr_offset: start of response buffer
  35  * @id: command to be executed
  36  * @buf: buffer returned from scm_legacy_get_command_buffer()
  37  *
  38  * An SCM command is laid out in memory as follows:
  39  *
  40  *      ------------------- <--- struct scm_legacy_command
  41  *      | command header  |
  42  *      ------------------- <--- scm_legacy_get_command_buffer()
  43  *      | command buffer  |
  44  *      ------------------- <--- struct scm_legacy_response and
  45  *      | response header |      scm_legacy_command_to_response()
  46  *      ------------------- <--- scm_legacy_get_response_buffer()
  47  *      | response buffer |
  48  *      -------------------
  49  *
  50  * There can be arbitrary padding between the headers and buffers so
  51  * you should always use the appropriate scm_legacy_get_*_buffer() routines
  52  * to access the buffers in a safe manner.
  53  */
  54 struct scm_legacy_command {
  55         __le32 len;
  56         __le32 buf_offset;
  57         __le32 resp_hdr_offset;
  58         __le32 id;
  59         __le32 buf[0];
  60 };
  61
  62 /**
  63  * struct scm_legacy_response - one SCM response buffer
  64  * @len: total available memory for response
  65  * @buf_offset: start of response data relative to start of scm_legacy_response
  66  * @is_complete: indicates if the command has finished processing
  67  */
  68 struct scm_legacy_response {
  69         __le32 len;
  70         __le32 buf_offset;
  71         __le32 is_complete;
  72 };
  73
  74 /**
  75  * scm_legacy_command_to_response() - Get a pointer to a scm_legacy_response
  76  * @cmd: command
  77  *
  78  * Returns a pointer to a response for a command.
  79  */
  80 static inline struct scm_legacy_response *scm_legacy_command_to_response(
  81                 const struct scm_legacy_command *cmd)
  82 {
  83         return (void *)cmd + le32_to_cpu(cmd->resp_hdr_offset);
  84 }
  85
  86 /**
  87  * scm_legacy_get_command_buffer() - Get a pointer to a command buffer
  88  * @cmd: command
  89  *
  90  * Returns a pointer to the command buffer of a command.
  91  */
  92 static inline void *scm_legacy_get_command_buffer(
  93                 const struct scm_legacy_command *cmd)
  94 {
  95         return (void *)cmd->buf;
  96 }
  97
  98 /**
  99  * scm_legacy_get_response_buffer() - Get a pointer to a response buffer
 100  * @rsp: response
 101  *
 102  * Returns a pointer to a response buffer of a response.
 103  */
 104 static inline void *scm_legacy_get_response_buffer(
 105                 const struct scm_legacy_response *rsp)
 106 {
 107         return (void *)rsp + le32_to_cpu(rsp->buf_offset);
 108 }
 109
 110 static void __scm_legacy_do(const struct arm_smccc_args *smc,
 111                             struct arm_smccc_res *res)
 112 {
 113         do {
 114                 arm_smccc_smc(smc->args[0], smc->args[1], smc->args[2],
 115                               smc->args[3], smc->args[4], smc->args[5],
 116                               smc->args[6], smc->args[7], res);
 117         } while (res->a0 == QCOM_SCM_INTERRUPTED);
 118 }
 119
 120 /**
 121  * qcom_scm_call() - Sends a command to the SCM and waits for the command to
 122  * finish processing.
 123  *
 124  * A note on cache maintenance:
 125  * Note that any buffers that are expected to be accessed by the secure world
 126  * must be flushed before invoking qcom_scm_call and invalidated in the cache
 127  * immediately after qcom_scm_call returns. Cache maintenance on the command
 128  * and response buffers is taken care of by qcom_scm_call; however, callers are
 129  * responsible for any other cached buffers passed over to the secure world.
 130  */
 131 int scm_legacy_call(struct device *dev, const struct qcom_scm_desc *desc,
 132                     struct qcom_scm_res *res)
 133 {
 134         u8 arglen = desc->arginfo & 0xf;
 135         int ret = 0, context_id;
 136         unsigned int i;
 137         struct scm_legacy_command *cmd;
 138         struct scm_legacy_response *rsp;
 139         struct arm_smccc_args smc = {0};
 140         struct arm_smccc_res smc_res;
 141         const size_t cmd_len = arglen * sizeof(__le32);
 142         const size_t resp_len = MAX_QCOM_SCM_RETS * sizeof(__le32);
 143         size_t alloc_len = sizeof(*cmd) + cmd_len + sizeof(*rsp) + resp_len;
 144         dma_addr_t cmd_phys;
 145         __le32 *arg_buf;
 146         const __le32 *res_buf;
 147
 148         cmd = kzalloc(PAGE_ALIGN(alloc_len), GFP_KERNEL);
 149         if (!cmd)
 150                 return -ENOMEM;
 151
 152         cmd->len = cpu_to_le32(alloc_len);
 153         cmd->buf_offset = cpu_to_le32(sizeof(*cmd));
 154         cmd->resp_hdr_offset = cpu_to_le32(sizeof(*cmd) + cmd_len);
 155         cmd->id = cpu_to_le32(SCM_LEGACY_FNID(desc->svc, desc->cmd));
 156
 157         arg_buf = scm_legacy_get_command_buffer(cmd);
 158         for (i = 0; i < arglen; i++)
 159                 arg_buf[i] = cpu_to_le32(desc->args[i]);
 160
 161         rsp = scm_legacy_command_to_response(cmd);
 162
 163         cmd_phys = dma_map_single(dev, cmd, alloc_len, DMA_TO_DEVICE);
 164         if (dma_mapping_error(dev, cmd_phys)) {
 165                 kfree(cmd);
 166                 return -ENOMEM;
 167         }
 168
 169         smc.args[0] = 1;
 170         smc.args[1] = (unsigned long)&context_id;
 171         smc.args[2] = cmd_phys;
 172
 173         mutex_lock(&qcom_scm_lock);
 174         __scm_legacy_do(&smc, &smc_res);
 175         if (smc_res.a0)
 176                 ret = qcom_scm_remap_error(smc_res.a0);
 177         mutex_unlock(&qcom_scm_lock);
 178         if (ret)
 179                 goto out;
 180
 181         do {
 182                 dma_sync_single_for_cpu(dev, cmd_phys + sizeof(*cmd) + cmd_len,
 183                                         sizeof(*rsp), DMA_FROM_DEVICE);
 184         } while (!rsp->is_complete);
 185
 186         dma_sync_single_for_cpu(dev, cmd_phys + sizeof(*cmd) + cmd_len +
 187                                 le32_to_cpu(rsp->buf_offset),
 188                                 resp_len, DMA_FROM_DEVICE);
 189
 190         if (res) {
 191                 res_buf = scm_legacy_get_response_buffer(rsp);
 192                 for (i = 0; i < MAX_QCOM_SCM_RETS; i++)
 193                         res->result[i] = le32_to_cpu(res_buf[i]);
 194         }
 195 out:
 196         dma_unmap_single(dev, cmd_phys, alloc_len, DMA_TO_DEVICE);
 197         kfree(cmd);
 198         return ret;
 199 }
 200
 201 #define SCM_LEGACY_ATOMIC_N_REG_ARGS    5
 202 #define SCM_LEGACY_ATOMIC_FIRST_REG_IDX 2
 203 #define SCM_LEGACY_CLASS_REGISTER               (0x2 << 8)
 204 #define SCM_LEGACY_MASK_IRQS            BIT(5)
 205 #define SCM_LEGACY_ATOMIC_ID(svc, cmd, n) \
 206                                 ((SCM_LEGACY_FNID(svc, cmd) << 12) | \
 207                                 SCM_LEGACY_CLASS_REGISTER | \
 208                                 SCM_LEGACY_MASK_IRQS | \
 209                                 (n & 0xf))
 210
 211 /**
 212  * qcom_scm_call_atomic() - Send an atomic SCM command with up to 5 arguments
 213  * and 3 return values
 214  * @desc: SCM call descriptor containing arguments
 215  * @res:  SCM call return values
 216  *
 217  * This shall only be used with commands that are guaranteed to be
 218  * uninterruptable, atomic and SMP safe.
 219  */
 220 int scm_legacy_call_atomic(struct device *unused,
 221                            const struct qcom_scm_desc *desc,
 222                            struct qcom_scm_res *res)
 223 {
 224         int context_id;
 225         struct arm_smccc_res smc_res;
 226         size_t arglen = desc->arginfo & 0xf;
 227
 228         BUG_ON(arglen > SCM_LEGACY_ATOMIC_N_REG_ARGS);
 229
 230         arm_smccc_smc(SCM_LEGACY_ATOMIC_ID(desc->svc, desc->cmd, arglen),
 231                       (unsigned long)&context_id,
 232                       desc->args[0], desc->args[1], desc->args[2],
 233                       desc->args[3], desc->args[4], 0, &smc_res);
 234
 235         if (res) {
 236                 res->result[0] = smc_res.a1;
 237                 res->result[1] = smc_res.a2;
 238                 res->result[2] = smc_res.a3;
 239         }
 240
 241         return smc_res.a0;
 242 }