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
39static 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 */
65struct 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 */
79struct 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 */
95static 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 */
116static 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 */
127static 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 */
139static 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 */
150static inline void *scm_get_response_buffer(const struct scm_response *rsp)
151{
152	return (void *)rsp + rsp->buf_offset;
153}
154
155static 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
171static 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
195static 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 */
224int 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);
259out:
260	free_scm_command(cmd);
261	return ret;
262}
263EXPORT_SYMBOL(scm_call);
264
265u32 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			"smc	#0	@ switch to secure world\n"
286			: "=r" (r0), "=r" (r1)
287			: "r" (r0), "r" (r1)
288			: "r2", "r3");
289	} while (r0 == SCM_INTERRUPTED);
290
291	version = r1;
292	mutex_unlock(&scm_lock);
293
294	return version;
295}
296EXPORT_SYMBOL(scm_get_version);
297