/* Copyright (c) 2010, Code Aurora Forum. All rights reserved.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 and
* only version 2 as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA.
*/
#include <linux/slab.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/errno.h>
#include <linux/err.h>
#include <asm/cacheflush.h>
#include "scm.h"
/* Cache line size for msm8x60 */
#define CACHELINESIZE 32
#define SCM_ENOMEM -5
#define SCM_EOPNOTSUPP -4
#define SCM_EINVAL_ADDR -3
#define SCM_EINVAL_ARG -2
#define SCM_ERROR -1
#define SCM_INTERRUPTED 1
static DEFINE_MUTEX(scm_lock);
/**
* struct scm_command - one SCM command buffer
* @len: total available memory for command and response
* @buf_offset: start of command buffer
* @resp_hdr_offset: start of response buffer
* @id: command to be executed
* @buf: buffer returned from scm_get_command_buffer()
*
* An SCM command is laid out in memory as follows:
*
* ------------------- <--- struct scm_command
* | command header |
* ------------------- <--- scm_get_command_buffer()
* | command buffer |
* ------------------- <--- struct scm_response and
* | response header | scm_command_to_response()
* ------------------- <--- scm_get_response_buffer()
* | response buffer |
* -------------------
*
* There can be arbitrary padding between the headers and buffers so
* you should always use the appropriate scm_get_*_buffer() routines
* to access the buffers in a safe manner.
*/
struct scm_command {
u32 len;
u32 buf_offset;
u32 resp_hdr_offset;
u32 id;
u32 buf[0];
};
/**
* struct scm_response - one SCM response buffer
* @len: total available memory for response
* @buf_offset: start of response data relative to start of scm_response
* @is_complete: indicates if the command has finished processing
*/
struct scm_response {
u32 len;
u32 buf_offset;
u32 is_complete;
};
/**
* alloc_scm_command() - Allocate an SCM command
* @cmd_size: size of the command buffer
* @resp_size: size of the response buffer
*
* Allocate an SCM command, including enough room for the command
* and response headers as well as the command and response buffers.
*
* Returns a valid &scm_command on success or %NULL if the allocation fails.
*/
static struct scm_command *alloc_scm_command(size_t cmd_size, size_t resp_size)
{
struct scm_command *cmd;
size_t len = sizeof(*cmd) + sizeof(struct scm_response) + cmd_size +
resp_size;
cmd = kzalloc(PAGE_ALIGN(len), GFP_KERNEL);
if (cmd) {
cmd->len = len;
cmd->buf_offset = offsetof(struct scm_command, buf);
cmd->resp_hdr_offset = cmd->buf_offset + cmd_size;
}
return cmd;
}
/**
* free_scm_command() - Free an SCM command
* @cmd: command to free
*
* Free an SCM command.
*/
static inline void free_scm_command(struct scm_command *cmd)
{
kfree(cmd);
}
/**
* scm_command_to_response() - Get a pointer to a scm_response
* @cmd: command
*
* Returns a pointer to a response for a command.
*/
static inline struct scm_response *scm_command_to_response(
const struct scm_command *cmd)
{
return (void *)cmd + cmd->resp_hdr_offset;
}
/**
* scm_get_command_buffer() - Get a pointer to a command buffer
* @cmd: command
*
* Returns a pointer to the command buffer of a command.
*/
static inline void *scm_get_command_buffer(const struct scm_command *cmd)
{
return (void *)cmd->buf;
}
/**
* scm_get_response_buffer() - Get a pointer to a response buffer
* @rsp: response
*
* Returns a pointer to a response buffer of a response.
*/
static inline void *scm_get_response_buffer(const struct scm_response *rsp)
{
return (void *)rsp + rsp->buf_offset;
}
static int scm_remap_error(int err)
{
switch (err) {
case SCM_ERROR:
return -EIO;
case SCM_EINVAL_ADDR:
case SCM_EINVAL_ARG:
return -EINVAL;
case SCM_EOPNOTSUPP:
return -EOPNOTSUPP;
case SCM_ENOMEM:
return -ENOMEM;
}
return -EINVAL;
}
static u32 smc(u32 cmd_addr)
{
int context_id;
register u32 r0 asm("r0") = 1;
register u32 r1 asm("r1") = (u32)&context_id;
register u32 r2 asm("r2") = cmd_addr;
do {
asm volatile(
__asmeq("%0", "r0")
__asmeq("%1", "r0")
__asmeq("%2", "r1")
__asmeq("%3", "r2")
"smc #0 @ switch to secure world\n"
: "=r" (r0)
: "r" (r0), "r" (r1), "r" (r2)
: "r3");
} while (r0 == SCM_INTERRUPTED);
return r0;
}
static int __scm_call(const struct scm_command *cmd)
{
int ret;
u32 cmd_addr = virt_to_phys(cmd);
/*
* Flush the entire cache here so callers don't have to remember
* to flush the cache when passing physical addresses to the secure
* side in the buffer.
*/
flush_cache_all();
ret = smc(cmd_addr);
if (ret < 0)
ret = scm_remap_error(ret);
return ret;
}
/**
* scm_call() - Send an SCM command
* @svc_id: service identifier
* @cmd_id: command identifier
* @cmd_buf: command buffer
* @cmd_len: length of the command buffer
* @resp_buf: response buffer
* @resp_len: length of the response buffer
*
* Sends a command to the SCM and waits for the command to finish processing.
*/
int scm_call(u32 svc_id, u32 cmd_id, const void *cmd_buf, size_t cmd_len,
void *resp_buf, size_t resp_len)
{
int ret;
struct scm_command *cmd;
struct scm_response *rsp;
cmd = alloc_scm_command(cmd_len, resp_len);
if (!cmd)
return -ENOMEM;
cmd->id = (svc_id << 10) | cmd_id;
if (cmd_buf)
memcpy(scm_get_command_buffer(cmd), cmd_buf, cmd_len);
mutex_lock(&scm_lock);
ret = __scm_call(cmd);
mutex_unlock(&scm_lock);
if (ret)
goto out;
rsp = scm_command_to_response(cmd);
do {
u32 start = (u32)rsp;
u32 end = (u32)scm_get_response_buffer(rsp) + resp_len;
start &= ~(CACHELINESIZE - 1);
while (start < end) {
asm ("mcr p15, 0, %0, c7, c6, 1" : : "r" (start)
: "memory");
start += CACHELINESIZE;
}
} while (!rsp->is_complete);
if (resp_buf)
memcpy(resp_buf, scm_get_response_buffer(rsp), resp_len);
out:
free_scm_command(cmd);
return ret;
}
EXPORT_SYMBOL(scm_call);
u32 scm_get_version(void)
{
int context_id;
static u32 version = -1;
register u32 r0 asm("r0");
register u32 r1 asm("r1");
if (version != -1)
return version;
mutex_lock(&scm_lock);
r0 = 0x1 << 8;
r1 = (u32)&context_id;
do {
asm volatile(
__asmeq("%0", "r0")
__asmeq("%1", "r1")
__asmeq("%2", "r0")
__asmeq("%3", "r1")
"smc #0 @ switch to secure world\n"
: "=r" (r0), "=r" (r1)
: "r" (r0), "r" (r1)
: "r2", "r3");
} while (r0 == SCM_INTERRUPTED);
version = r1;
mutex_unlock(&scm_lock);
return version;
}
EXPORT_SYMBOL(scm_get_version);
