/* 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/outercache.h>
#include <asm/cacheflush.h>
#include "scm.h"
#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 {
__le32 len;
__le32 buf_offset;
__le32 resp_hdr_offset;
__le32 id;
__le32 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 {
__le32 len;
__le32 buf_offset;
__le32 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;
u32 offset;
cmd = kzalloc(PAGE_ALIGN(len), GFP_KERNEL);
if (cmd) {
cmd->len = cpu_to_le32(len);
offset = offsetof(struct scm_command, buf);
cmd->buf_offset = cpu_to_le32(offset);
cmd->resp_hdr_offset = cpu_to_le32(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 + le32_to_cpu(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 + le32_to_cpu(rsp->buf_offset);
}
static int scm_remap_error(int err)
{
pr_err("scm_call failed with error code %d\n", 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")
#ifdef REQUIRES_SEC
".arch_extension sec\n"
#endif
"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 command buffer so that the secure world sees
* the correct data.
*/
__cpuc_flush_dcache_area((void *)cmd, cmd->len);
outer_flush_range(cmd_addr, cmd_addr + cmd->len);
ret = smc(cmd_addr);
if (ret < 0)
ret = scm_remap_error(ret);
return ret;
}
static void scm_inv_range(unsigned long start, unsigned long end)
{
u32 cacheline_size, ctr;
asm volatile("mrc p15, 0, %0, c0, c0, 1" : "=r" (ctr));
cacheline_size = 4 << ((ctr >> 16) & 0xf);
start = round_down(start, cacheline_size);
end = round_up(end, cacheline_size);
outer_inv_range(start, end);
while (start < end) {
asm ("mcr p15, 0, %0, c7, c6, 1" : : "r" (start)
: "memory");
start += cacheline_size;
}
dsb();
isb();
}
/**
* 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.
*
* A note on cache maintenance:
* Note that any buffers that are expected to be accessed by the secure world
* must be flushed before invoking scm_call and invalidated in the cache
* immediately after scm_call returns. Cache maintenance on the command and
* response buffers is taken care of by scm_call; however, callers are
* responsible for any other cached buffers passed over to the secure world.
*/
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;
unsigned long start, end;
cmd = alloc_scm_command(cmd_len, resp_len);
if (!cmd)
return -ENOMEM;
cmd->id = cpu_to_le32((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);
start = (unsigned long)rsp;
do {
scm_inv_range(start, start + sizeof(*rsp));
} while (!rsp->is_complete);
end = (unsigned long)scm_get_response_buffer(rsp) + resp_len;
scm_inv_range(start, end);
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")
#ifdef REQUIRES_SEC
".arch_extension sec\n"
#endif
"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);
