firmware: scmi: optee: use TEE shared memory for SCMI messages
Changes implementation when using TEE dynamically allocated shared
memory to synchronize with the Linux implementation where the legacy
SMT protocol cannot be used with such memory since it is expected from
device mapped memory whereas OP-TEE shared memory is cached and
hence should not be accessed using memcpy_toio()/memcpy_fromio().
This change implements the MSG shared memory protocol introduced
in Linux [1]. The protocol uses a simplified SMT header of 32bit
named MSG_SMT to carry SCMI protocol information and uses side channel
means to carry exchanged buffer size information, as TEE invocation API
parameters when used in the SCMI OP-TEE transport.
Link: [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=f301bba0ca7392d16a6ea4f1d264a91f1fadea1a
Signed-off-by: Etienne Carriere <etienne.carriere@linaro.org>
diff --git a/drivers/firmware/scmi/smt.h b/drivers/firmware/scmi/smt.h
index a8c0987..9d669a6 100644
--- a/drivers/firmware/scmi/smt.h
+++ b/drivers/firmware/scmi/smt.h
@@ -1,7 +1,7 @@
/* SPDX-License-Identifier: GPL-2.0 */
/*
* Copyright (c) 2015-2019, Arm Limited and Contributors. All rights reserved.
- * Copyright (C) 2019-2020 Linaro Limited.
+ * Copyright (C) 2019-2022 Linaro Limited.
*/
#ifndef SCMI_SMT_H
#define SCMI_SMT_H
@@ -29,6 +29,17 @@
u8 msg_payload[0];
};
+/**
+ * struct scmi_msg_header - Description of a MSG shared memory message buffer
+ *
+ * MSG communication protocol uses a 32bit header memory cell to store SCMI
+ * protocol data followed by the exchange SCMI message payload.
+ */
+struct scmi_smt_msg_header {
+ __le32 msg_header;
+ u8 msg_payload[0];
+};
+
#define SMT_HEADER_TOKEN(token) (((token) << 18) & GENMASK(31, 18))
#define SMT_HEADER_PROTOCOL_ID(proto) (((proto) << 10) & GENMASK(17, 10))
#define SMT_HEADER_MESSAGE_TYPE(type) (((type) << 18) & GENMASK(9, 8))
@@ -75,12 +86,44 @@
int scmi_dt_get_smt_buffer(struct udevice *dev, struct scmi_smt *smt);
+/*
+ * Write SCMI message to a SMT shared memory
+ * @dev: SCMI device
+ * @smt: Reference to shared memory using SMT header
+ * @msg: Input SCMI message transmitted
+ */
int scmi_write_msg_to_smt(struct udevice *dev, struct scmi_smt *smt,
struct scmi_msg *msg);
+/*
+ * Read SCMI message from a SMT shared memory
+ * @dev: SCMI device
+ * @smt: Reference to shared memory using SMT header
+ * @msg: Output SCMI message received
+ */
int scmi_read_resp_from_smt(struct udevice *dev, struct scmi_smt *smt,
struct scmi_msg *msg);
void scmi_clear_smt_channel(struct scmi_smt *smt);
+/*
+ * Write SCMI message to SMT_MSG shared memory
+ * @dev: SCMI device
+ * @smt: Reference to shared memory using SMT_MSG header
+ * @msg: Input SCMI message transmitted
+ * @buf_size: Size of the full SMT_MSG buffer transmitted
+ */
+int scmi_msg_to_smt_msg(struct udevice *dev, struct scmi_smt *smt,
+ struct scmi_msg *msg, size_t *buf_size);
+
+/*
+ * Read SCMI message from SMT_MSG shared memory
+ * @dev: SCMI device
+ * @smt: Reference to shared memory using SMT_MSG header
+ * @msg: Output SCMI message received
+ * @buf_size: Size of the full SMT_MSG buffer received
+ */
+int scmi_msg_from_smt_msg(struct udevice *dev, struct scmi_smt *smt,
+ struct scmi_msg *msg, size_t buf_size);
+
#endif /* SCMI_SMT_H */