arch/arm/mach-msm/scm.c

   1 /* Copyright (c) 2010, Code Aurora Forum. All rights reserved.
   2  *
   3  * This program is free software; you can redistribute it and/or modify
   4  * it under the terms of the GNU General Public License version 2 and
   5  * only version 2 as published by the Free Software Foundation.
   6  *
   7  * This program is distributed in the hope that it will be useful,
   8  * but WITHOUT ANY WARRANTY; without even the implied warranty of
   9  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  10  * GNU General Public License for more details.
  11  *
  12  * You should have received a copy of the GNU General Public License
  13  * along with this program; if not, write to the Free Software
  14  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  15  * 02110-1301, USA.
  16  */
  17
  18 #include <linux/slab.h>
  19 #include <linux/io.h>
  20 #include <linux/module.h>
  21 #include <linux/mutex.h>
  22 #include <linux/errno.h>
  23 #include <linux/err.h>
  24
  25 #include <asm/cacheflush.h>
  26
  27 #include "scm.h"
  28
  29 /* Cache line size for msm8x60 */
  30 #define CACHELINESIZE 32
  31
  32 #define SCM_ENOMEM              -5
  33 #define SCM_EOPNOTSUPP          -4
  34 #define SCM_EINVAL_ADDR         -3
  35 #define SCM_EINVAL_ARG          -2
  36 #define SCM_ERROR               -1
  37 #define SCM_INTERRUPTED         1
  38
  39 static DEFINE_MUTEX(scm_lock);
  40
  41 /**
  42  * struct scm_command - one SCM command buffer
  43  * @len: total available memory for command and response
  44  * @buf_offset: start of command buffer
  45  * @resp_hdr_offset: start of response buffer
  46  * @id: command to be executed
  47  * @buf: buffer returned from scm_get_command_buffer()
  48  *
  49  * An SCM command is laid out in memory as follows:
  50  *
  51  *      ------------------- <--- struct scm_command
  52  *      | command header  |
  53  *      ------------------- <--- scm_get_command_buffer()
  54  *      | command buffer  |
  55  *      ------------------- <--- struct scm_response and
  56  *      | response header |      scm_command_to_response()
  57  *      ------------------- <--- scm_get_response_buffer()
  58  *      | response buffer |
  59  *      -------------------
  60  *
  61  * There can be arbitrary padding between the headers and buffers so
  62  * you should always use the appropriate scm_get_*_buffer() routines
  63  * to access the buffers in a safe manner.
  64  */
  65 struct scm_command {
  66         u32     len;
  67         u32     buf_offset;
  68         u32     resp_hdr_offset;
  69         u32     id;
  70         u32     buf[0];
  71 };
  72
  73 /**
  74  * struct scm_response - one SCM response buffer
  75  * @len: total available memory for response
  76  * @buf_offset: start of response data relative to start of scm_response
  77  * @is_complete: indicates if the command has finished processing
  78  */
  79 struct scm_response {
  80         u32     len;
  81         u32     buf_offset;
  82         u32     is_complete;
  83 };
  84
  85 /**
  86  * alloc_scm_command() - Allocate an SCM command
  87  * @cmd_size: size of the command buffer
  88  * @resp_size: size of the response buffer
  89  *
  90  * Allocate an SCM command, including enough room for the command
  91  * and response headers as well as the command and response buffers.
  92  *
  93  * Returns a valid &scm_command on success or %NULL if the allocation fails.
  94  */
  95 static struct scm_command *alloc_scm_command(size_t cmd_size, size_t resp_size)
  96 {
  97         struct scm_command *cmd;
  98         size_t len = sizeof(*cmd) + sizeof(struct scm_response) + cmd_size +
  99                 resp_size;
 100
 101         cmd = kzalloc(PAGE_ALIGN(len), GFP_KERNEL);
 102         if (cmd) {
 103                 cmd->len = len;
 104                 cmd->buf_offset = offsetof(struct scm_command, buf);
 105                 cmd->resp_hdr_offset = cmd->buf_offset + cmd_size;
 106         }
 107         return cmd;
 108 }
 109
 110 /**
 111  * free_scm_command() - Free an SCM command
 112  * @cmd: command to free
 113  *
 114  * Free an SCM command.
 115  */
 116 static inline void free_scm_command(struct scm_command *cmd)
 117 {
 118         kfree(cmd);
 119 }
 120
 121 /**
 122  * scm_command_to_response() - Get a pointer to a scm_response
 123  * @cmd: command
 124  *
 125  * Returns a pointer to a response for a command.
 126  */
 127 static inline struct scm_response *scm_command_to_response(
 128                 const struct scm_command *cmd)
 129 {
 130         return (void *)cmd + cmd->resp_hdr_offset;
 131 }
 132
 133 /**
 134  * scm_get_command_buffer() - Get a pointer to a command buffer
 135  * @cmd: command
 136  *
 137  * Returns a pointer to the command buffer of a command.
 138  */
 139 static inline void *scm_get_command_buffer(const struct scm_command *cmd)
 140 {
 141         return (void *)cmd->buf;
 142 }
 143
 144 /**
 145  * scm_get_response_buffer() - Get a pointer to a response buffer
 146  * @rsp: response
 147  *
 148  * Returns a pointer to a response buffer of a response.
 149  */
 150 static inline void *scm_get_response_buffer(const struct scm_response *rsp)
 151 {
 152         return (void *)rsp + rsp->buf_offset;
 153 }
 154
 155 static int scm_remap_error(int err)
 156 {
 157         switch (err) {
 158         case SCM_ERROR:
 159                 return -EIO;
 160         case SCM_EINVAL_ADDR:
 161         case SCM_EINVAL_ARG:
 162                 return -EINVAL;
 163         case SCM_EOPNOTSUPP:
 164                 return -EOPNOTSUPP;
 165         case SCM_ENOMEM:
 166                 return -ENOMEM;
 167         }
 168         return -EINVAL;
 169 }
 170
 171 static u32 smc(u32 cmd_addr)
 172 {
 173         int context_id;
 174         register u32 r0 asm("r0") = 1;
 175         register u32 r1 asm("r1") = (u32)&context_id;
 176         register u32 r2 asm("r2") = cmd_addr;
 177         do {
 178                 asm volatile(
 179                         __asmeq("%0", "r0")
 180                         __asmeq("%1", "r0")
 181                         __asmeq("%2", "r1")
 182                         __asmeq("%3", "r2")
 183                         "smc    #0      @ switch to secure world\n"
 184                         : "=r" (r0)
 185                         : "r" (r0), "r" (r1), "r" (r2)
 186                         : "r3");
 187         } while (r0 == SCM_INTERRUPTED);
 188
 189         return r0;
 190 }
 191
 192 static int __scm_call(const struct scm_command *cmd)
 193 {
 194         int ret;
 195         u32 cmd_addr = virt_to_phys(cmd);
 196
 197         /*
 198          * Flush the entire cache here so callers don't have to remember
 199          * to flush the cache when passing physical addresses to the secure
 200          * side in the buffer.
 201          */
 202         flush_cache_all();
 203         ret = smc(cmd_addr);
 204         if (ret < 0)
 205                 ret = scm_remap_error(ret);
 206
 207         return ret;
 208 }
 209
 210 /**
 211  * scm_call() - Send an SCM command
 212  * @svc_id: service identifier
 213  * @cmd_id: command identifier
 214  * @cmd_buf: command buffer
 215  * @cmd_len: length of the command buffer
 216  * @resp_buf: response buffer
 217  * @resp_len: length of the response buffer
 218  *
 219  * Sends a command to the SCM and waits for the command to finish processing.
 220  */
 221 int scm_call(u32 svc_id, u32 cmd_id, const void *cmd_buf, size_t cmd_len,
 222                 void *resp_buf, size_t resp_len)
 223 {
 224         int ret;
 225         struct scm_command *cmd;
 226         struct scm_response *rsp;
 227
 228         cmd = alloc_scm_command(cmd_len, resp_len);
 229         if (!cmd)
 230                 return -ENOMEM;
 231
 232         cmd->id = (svc_id << 10) | cmd_id;
 233         if (cmd_buf)
 234                 memcpy(scm_get_command_buffer(cmd), cmd_buf, cmd_len);
 235
 236         mutex_lock(&scm_lock);
 237         ret = __scm_call(cmd);
 238         mutex_unlock(&scm_lock);
 239         if (ret)
 240                 goto out;
 241
 242         rsp = scm_command_to_response(cmd);
 243         do {
 244                 u32 start = (u32)rsp;
 245                 u32 end = (u32)scm_get_response_buffer(rsp) + resp_len;
 246                 start &= ~(CACHELINESIZE - 1);
 247                 while (start < end) {
 248                         asm ("mcr p15, 0, %0, c7, c6, 1" : : "r" (start)
 249                              : "memory");
 250                         start += CACHELINESIZE;
 251                 }
 252         } while (!rsp->is_complete);
 253
 254         if (resp_buf)
 255                 memcpy(resp_buf, scm_get_response_buffer(rsp), resp_len);
 256 out:
 257         free_scm_command(cmd);
 258         return ret;
 259 }
 260 EXPORT_SYMBOL(scm_call);
 261
 262 u32 scm_get_version(void)
 263 {
 264         int context_id;
 265         static u32 version = -1;
 266         register u32 r0 asm("r0");
 267         register u32 r1 asm("r1");
 268
 269         if (version != -1)
 270                 return version;
 271
 272         mutex_lock(&scm_lock);
 273
 274         r0 = 0x1 << 8;
 275         r1 = (u32)&context_id;
 276         do {
 277                 asm volatile(
 278                         __asmeq("%0", "r0")
 279                         __asmeq("%1", "r1")
 280                         __asmeq("%2", "r0")
 281                         __asmeq("%3", "r1")
 282                         "smc    #0      @ switch to secure world\n"
 283                         : "=r" (r0), "=r" (r1)
 284                         : "r" (r0), "r" (r1)
 285                         : "r2", "r3");
 286         } while (r0 == SCM_INTERRUPTED);
 287
 288         version = r1;
 289         mutex_unlock(&scm_lock);
 290
 291         return version;
 292 }
 293 EXPORT_SYMBOL(scm_get_version);