linux/drivers/firmware/qcom_scm-legacy.c
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   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
  18static 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 */
  25struct 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 */
  54struct scm_legacy_command {
  55        __le32 len;
  56        __le32 buf_offset;
  57        __le32 resp_hdr_offset;
  58        __le32 id;
  59        __le32 buf[];
  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 */
  68struct 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 */
  80static 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 */
  92static 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 */
 104static 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
 110static 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 * scm_legacy_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 */
 131int 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        }
 195out:
 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 * scm_legacy_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 */
 220int 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}
 243