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Linux/arch/arm/mach-msm/scm.c

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  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 #ifdef REQUIRES_SEC
184                         ".arch_extension sec\n"
185 #endif
186                         "smc    #0      @ switch to secure world\n"
187                         : "=r" (r0)
188                         : "r" (r0), "r" (r1), "r" (r2)
189                         : "r3");
190         } while (r0 == SCM_INTERRUPTED);
191 
192         return r0;
193 }
194 
195 static int __scm_call(const struct scm_command *cmd)
196 {
197         int ret;
198         u32 cmd_addr = virt_to_phys(cmd);
199 
200         /*
201          * Flush the entire cache here so callers don't have to remember
202          * to flush the cache when passing physical addresses to the secure
203          * side in the buffer.
204          */
205         flush_cache_all();
206         ret = smc(cmd_addr);
207         if (ret < 0)
208                 ret = scm_remap_error(ret);
209 
210         return ret;
211 }
212 
213 /**
214  * scm_call() - Send an SCM command
215  * @svc_id: service identifier
216  * @cmd_id: command identifier
217  * @cmd_buf: command buffer
218  * @cmd_len: length of the command buffer
219  * @resp_buf: response buffer
220  * @resp_len: length of the response buffer
221  *
222  * Sends a command to the SCM and waits for the command to finish processing.
223  */
224 int scm_call(u32 svc_id, u32 cmd_id, const void *cmd_buf, size_t cmd_len,
225                 void *resp_buf, size_t resp_len)
226 {
227         int ret;
228         struct scm_command *cmd;
229         struct scm_response *rsp;
230 
231         cmd = alloc_scm_command(cmd_len, resp_len);
232         if (!cmd)
233                 return -ENOMEM;
234 
235         cmd->id = (svc_id << 10) | cmd_id;
236         if (cmd_buf)
237                 memcpy(scm_get_command_buffer(cmd), cmd_buf, cmd_len);
238 
239         mutex_lock(&scm_lock);
240         ret = __scm_call(cmd);
241         mutex_unlock(&scm_lock);
242         if (ret)
243                 goto out;
244 
245         rsp = scm_command_to_response(cmd);
246         do {
247                 u32 start = (u32)rsp;
248                 u32 end = (u32)scm_get_response_buffer(rsp) + resp_len;
249                 start &= ~(CACHELINESIZE - 1);
250                 while (start < end) {
251                         asm ("mcr p15, 0, %0, c7, c6, 1" : : "r" (start)
252                              : "memory");
253                         start += CACHELINESIZE;
254                 }
255         } while (!rsp->is_complete);
256 
257         if (resp_buf)
258                 memcpy(resp_buf, scm_get_response_buffer(rsp), resp_len);
259 out:
260         free_scm_command(cmd);
261         return ret;
262 }
263 EXPORT_SYMBOL(scm_call);
264 
265 u32 scm_get_version(void)
266 {
267         int context_id;
268         static u32 version = -1;
269         register u32 r0 asm("r0");
270         register u32 r1 asm("r1");
271 
272         if (version != -1)
273                 return version;
274 
275         mutex_lock(&scm_lock);
276 
277         r0 = 0x1 << 8;
278         r1 = (u32)&context_id;
279         do {
280                 asm volatile(
281                         __asmeq("%0", "r0")
282                         __asmeq("%1", "r1")
283                         __asmeq("%2", "r0")
284                         __asmeq("%3", "r1")
285 #ifdef REQUIRES_SEC
286                         ".arch_extension sec\n"
287 #endif
288                         "smc    #0      @ switch to secure world\n"
289                         : "=r" (r0), "=r" (r1)
290                         : "r" (r0), "r" (r1)
291                         : "r2", "r3");
292         } while (r0 == SCM_INTERRUPTED);
293 
294         version = r1;
295         mutex_unlock(&scm_lock);
296 
297         return version;
298 }
299 EXPORT_SYMBOL(scm_get_version);
300 

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