[PATCH v2 2/6] msm: Secure Channel Manager (SCM) support

Jeff Ohlstein
2010-12-08T04:29:28Z

From: Stephen Boyd <sboyd@codeaurora.org>

SCM is the protocol used to communicate between the secure and
non-secure code executing on the applications processor. The
non-secure side uses a physically contiguous buffer to pass
information to the secure side; where the buffer conforms to a
format that is agreed upon by both sides. The use of a buffer
allows multiple pending requests to be in flight on the secure
side. It also benefits use cases where the command or response
buffer contains large chunks of data.

Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
---
arch/arm/mach-msm/Kconfig | 4 +
arch/arm/mach-msm/Makefile | 1 +
arch/arm/mach-msm/scm.c | 280 ++++++++++++++++++++++++++++++++++++++++++++
arch/arm/mach-msm/scm.h | 41 +++++++
4 files changed, 326 insertions(+), 0 deletions(-)
create mode 100644 arch/arm/mach-msm/scm.c
create mode 100644 arch/arm/mach-msm/scm.h

diff --git a/arch/arm/mach-msm/Kconfig b/arch/arm/mach-msm/Kconfig
index 31e5fd6..ab5338f 100644
--- a/arch/arm/mach-msm/Kconfig
+++ b/arch/arm/mach-msm/Kconfig
@@ -44,6 +44,7 @@ config ARCH_MSM8X60
select CPU_V7
select MSM_V2_TLMM
select MSM_GPIOMUX
+ select MSM_SCM if SMP

endchoice

@@ -164,4 +165,7 @@ config MSM_GPIOMUX

config MSM_V2_TLMM
bool
+
+config MSM_SCM
+ bool
endif
diff --git a/arch/arm/mach-msm/Makefile b/arch/arm/mach-msm/Makefile
index b5a7b07..eed503b 100644
--- a/arch/arm/mach-msm/Makefile
+++ b/arch/arm/mach-msm/Makefile
@@ -18,6 +18,7 @@ obj-$(CONFIG_MSM_PROC_COMM) += clock.o
obj-$(CONFIG_ARCH_QSD8X50) += sirc.o
obj-$(CONFIG_MSM_SMD) += smd.o smd_debug.o
obj-$(CONFIG_MSM_SMD) += last_radio_log.o
+obj-$(CONFIG_MSM_SCM) += scm.o

obj-$(CONFIG_MACH_TROUT) += board-trout.o board-trout-gpio.o board-trout-mmc.o devices-msm7x00.o
obj-$(CONFIG_MACH_HALIBUT) += board-halibut.o devices-msm7x00.o
diff --git a/arch/arm/mach-msm/scm.c b/arch/arm/mach-msm/scm.c
new file mode 100644
index 0000000..85ed2cc
--- /dev/null
+++ b/arch/arm/mach-msm/scm.c
@@ -0,0 +1,280 @@
+/* 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 <linux/dma-mapping.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
+ *
+ * An SCM command is layed 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;
+};
+
+/**
+ * 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
+ * @handle: dma handle
+ *
+ * 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,
+ dma_addr_t *handle)
+{
+ struct scm_command *cmd;
+ size_t len = sizeof(*cmd) + sizeof(struct scm_response) + cmd_size +
+ resp_size;
+
+ cmd = dma_alloc_coherent(NULL, len, handle, GFP_KERNEL);
+ if (cmd) {
+ cmd->len = len;
+ cmd->buf_offset = sizeof(*cmd);
+ cmd->resp_hdr_offset = cmd->buf_offset + cmd_size;
+ }
+ return cmd;
+}
+
+/**
+ * free_scm_command() - Free an SCM command
+ * @cmd: command to free
+ * @handle: dma handle
+ *
+ * Free an SCM command.
+ */
+static inline void free_scm_command(struct scm_command *cmd, dma_addr_t handle)
+{
+ dma_free_coherent(NULL, cmd->len, cmd, handle);
+}
+
+/**
+ * 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 + cmd->buf_offset;
+}
+
+/**
+ * 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(dma_addr_t cmd_addr)
+{
+ int context_id;
+ register u32 r0 asm("r0") = 1;
+ register u32 r1 asm("r1") = (u32)&context_id;
+ register u32 r2 asm("r2") = (u32)cmd_addr;
+ asm(
+ __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");
+ return r0;
+}
+
+static int __scm_call(const dma_addr_t cmd)
+{
+ int ret;
+
+ /*
+ * 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();
+ do {
+ ret = smc(cmd);
+ if (ret < 0) {
+ ret = scm_remap_error(ret);
+ break;
+ }
+ } while (ret == SCM_INTERRUPTED);
+
+ 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;
+ dma_addr_t handle;
+
+ cmd = alloc_scm_command(cmd_len, resp_len, &handle);
+ if (!cmd)
+ return -ENOMEM;
+
+ cmd->id = (svc_id << 10) | cmd_id;
+ if (cmd_buf)
+ memcpy(scm_get_command_buffer(cmd), cmd_buf, cmd_len);
+ wmb();
+
+ mutex_lock(&scm_lock);
+ ret = __scm_call(handle);
+ mutex_unlock(&scm_lock);
+ if (ret)
+ goto out;
+
+ rsp = scm_command_to_response(cmd);
+ do {
+ rmb();
+ } while (!rsp->is_complete);
+
+ if (resp_buf)
+ memcpy(resp_buf, scm_get_response_buffer(rsp), resp_len);
+out:
+ free_scm_command(cmd, handle);
+ return ret;
+}
+EXPORT_SYMBOL(scm_call);
+
+u32 scm_get_version(void)
+{
+ int context_id;
+ static u32 version = -1;
+ register u32 r0 asm("r0") = 0x1 << 8;
+ register u32 r1 asm("r1") = (u32)&context_id;
+
+ if (version != -1)
+ return version;
+
+ mutex_lock(&scm_lock);
+ asm(
+ __asmeq("%0", "r1")
+ __asmeq("%1", "r0")
+ __asmeq("%2", "r1")
+ "smc #0 @ switch to secure world\n"
+ : "=r" (r1)
+ : "r" (r0), "r" (r1)
+ : "r2", "r3");
+ version = r1;
+ mutex_unlock(&scm_lock);
+
+ return version;
+}
+EXPORT_SYMBOL(scm_get_version);
diff --git a/arch/arm/mach-msm/scm.h b/arch/arm/mach-msm/scm.h
new file mode 100644
index 0000000..261786b
--- /dev/null
+++ b/arch/arm/mach-msm/scm.h
@@ -0,0 +1,41 @@
+/* Copyright (c) 2010, Code Aurora Forum. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ * * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following
+ * disclaimer in the documentation and/or other materials provided
+ * with the distribution.
+ * * Neither the name of Code Aurora Forum, Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived
+ * from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED "AS IS" AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS
+ * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
+ * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+ * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
+ * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN
+ * IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+#ifndef __MACH_SCM_H
+#define __MACH_SCM_H
+
+#define SCM_SVC_BOOT 0x1
+#define SCM_SVC_PIL 0x2
+
+extern int scm_call(u32 svc_id, u32 cmd_id, const void *cmd_buf, size_t cmd_len,
+ void *resp_buf, size_t resp_len);
+
+#define SCM_VERSION(major, minor) (((major) << 16) | ((minor) & 0xFF))
+
+extern u32 scm_get_version(void);
+
+#endif