Merge pull request #963 from soby-mathew/sm/scmi_dev

Add SCMI power domain and system power protocol support

docs/user-guide.md

@@ -622,6 +622,10 @@ map is explained in the [Firmware Design].
     SCP_BL2U to the FIP and FWU_FIP respectively, and enables them to be loaded
     during boot. Default is 1.
 
+*   `CSS_USE_SCMI_DRIVER`: Boolean flag which selects SCMI driver instead of
+    SCPI driver for communicating with the SCP during power management operations.
+    If this option is set to 1, then SCMI driver will be used. Default is 0.
+
 #### ARM FVP platform specific build options
 
 *   `FVP_CLUSTER_COUNT`    : Configures the cluster count to be used to

include/plat/arm/common/plat_arm.h

@@ -46,7 +46,7 @@ void arm_setup_page_tables(uintptr_t total_base,
  * arm_lock_xxx() macros
  */
 #define ARM_INSTANTIATE_LOCK	DEFINE_BAKERY_LOCK(arm_lock);
-
+#define ARM_LOCK_GET_INSTANCE	(&arm_lock)
 /*
  * These are wrapper macros to the Coherent Memory Bakery Lock API.
  */
@@ -60,6 +60,7 @@ void arm_setup_page_tables(uintptr_t total_base,
  * Empty macros for all other BL stages other than BL31 and BL32
  */
 #define ARM_INSTANTIATE_LOCK
+#define ARM_LOCK_GET_INSTANCE	0
 #define arm_lock_init()
 #define arm_lock_get()
 #define arm_lock_release()

include/plat/arm/css/common/css_def.h

 /*
- * Copyright (c) 2015-2016, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2015-2017, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -47,6 +47,17 @@
 					CSS_IRQ_TZ_WDOG,	\
 					CSS_IRQ_SEC_SYS_TIMER
 
+/*
+ * The lower Non-secure MHU channel is being used for SCMI for ARM Trusted
+ * Firmware.
+ * TODO: Move SCMI to Secure channel once the migration to SCMI in SCP is
+ * complete.
+ */
+#define MHU_CPU_INTR_L_SET_OFFSET	0x108
+#define MHU_CPU_INTR_H_SET_OFFSET	0x128
+#define CSS_SCMI_PAYLOAD_BASE		(NSRAM_BASE + 0x500)
+#define CSS_SCMI_MHU_DB_REG_OFF		MHU_CPU_INTR_L_SET_OFFSET
+
 /*
  * SCP <=> AP boot configuration
  *
@@ -63,6 +74,11 @@
 						CSS_DEVICE_SIZE,	\
 						MT_DEVICE | MT_RW | MT_SECURE)
 
+#define CSS_MAP_NSRAM			MAP_REGION_FLAT(		\
+						NSRAM_BASE,	\
+						NSRAM_SIZE,	\
+						MT_DEVICE | MT_RW | MT_SECURE)
+
 /* Platform ID address */
 #define SSC_VERSION_OFFSET			0x040
 

plat/arm/board/common/board_css_common.c

@@ -49,6 +49,15 @@ const mmap_region_t plat_arm_mmap[] = {
 	ARM_MAP_SHARED_RAM,
 	V2M_MAP_IOFPGA,
 	CSS_MAP_DEVICE,
+#if CSS_USE_SCMI_DRIVER
+	/*
+	 * The SCMI payload area is currently in the Non Secure SRAM. This is
+	 * a potential security risk but this will be resolved once SCP
+	 * completely replaces SCPI with SCMI as the only communication
+	 * protocol.
+	 */
+	CSS_MAP_NSRAM,
+#endif
 	SOC_CSS_MAP_DEVICE,
 	{0}
 };

plat/arm/board/juno/include/platform_def.h

@@ -74,8 +74,13 @@
 #endif
 
 #ifdef IMAGE_BL31
+# if CSS_USE_SCMI_DRIVER
+#  define PLAT_ARM_MMAP_ENTRIES		6
+#  define MAX_XLAT_TABLES		3
+# else
 #  define PLAT_ARM_MMAP_ENTRIES		5
 #  define MAX_XLAT_TABLES		2
+# endif
 #endif
 
 #ifdef IMAGE_BL32

plat/arm/board/juno/juno_topology.c

@@ -51,3 +51,10 @@ unsigned int plat_arm_get_cluster_core_count(u_register_t mpidr)
 	return (((mpidr) & 0x100) ? JUNO_CLUSTER1_CORE_COUNT :\
 				JUNO_CLUSTER0_CORE_COUNT);
 }
+
+/*
+ * The array mapping platform core position (implemented by plat_my_core_pos())
+ * to the SCMI power domain ID implemented by SCP.
+ */
+const uint32_t plat_css_core_pos_to_scmi_dmn_id_map[PLATFORM_CORE_COUNT] = {
+			2, 3, 4, 5, 0, 1 };

plat/arm/css/common/css_common.mk

 #
-# Copyright (c) 2015-2016, ARM Limited and Contributors. All rights reserved.
+# Copyright (c) 2015-2017, ARM Limited and Contributors. All rights reserved.
 #
 # SPDX-License-Identifier: BSD-3-Clause
 #
@@ -8,6 +8,9 @@
 # By default, SCP images are needed by CSS platforms.
 CSS_LOAD_SCP_IMAGES	?=	1
 
+# By default, SCMI driver is disabled for CSS platforms
+CSS_USE_SCMI_DRIVER	?=	0
+
 PLAT_INCLUDES		+=	-Iinclude/plat/arm/css/common			\
 				-Iinclude/plat/arm/css/common/aarch64
 
@@ -25,10 +28,18 @@ BL2U_SOURCES		+=	plat/arm/css/common/css_bl2u_setup.c		\
 				plat/arm/css/drivers/scpi/css_scpi.c
 
 BL31_SOURCES		+=	plat/arm/css/common/css_pm.c			\
-				plat/arm/css/common/css_topology.c		\
-				plat/arm/css/drivers/scp/css_pm_scpi.c		\
+				plat/arm/css/common/css_topology.c
+
+ifeq (${CSS_USE_SCMI_DRIVER},0)
+BL31_SOURCES		+=	plat/arm/css/drivers/scp/css_pm_scpi.c		\
 				plat/arm/css/drivers/scpi/css_mhu.c		\
 				plat/arm/css/drivers/scpi/css_scpi.c
+else
+BL31_SOURCES		+=	plat/arm/css/drivers/scp/css_pm_scmi.c		\
+				plat/arm/css/drivers/scmi/scmi_common.c		\
+				plat/arm/css/drivers/scmi/scmi_pwr_dmn_proto.c	\
+				plat/arm/css/drivers/scmi/scmi_sys_pwr_proto.c
+endif
 
 ifneq (${RESET_TO_BL31},0)
   $(error "Using BL31 as the reset vector is not supported on CSS platforms. \
@@ -56,3 +67,8 @@ CSS_DETECT_PRE_1_7_0_SCP	:=	1
 # Process CSS_DETECT_PRE_1_7_0_SCP flag
 $(eval $(call assert_boolean,CSS_DETECT_PRE_1_7_0_SCP))
 $(eval $(call add_define,CSS_DETECT_PRE_1_7_0_SCP))
+
+# Process CSS_USE_SCMI_DRIVER flag
+$(eval $(call assert_boolean,CSS_USE_SCMI_DRIVER))
+$(eval $(call add_define,CSS_USE_SCMI_DRIVER))
+

plat/arm/css/drivers/scmi/scmi.h

+/*
+ * Copyright (c) 2017, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#ifndef __CSS_SCMI_H__
+#define __CSS_SCMI_H__
+
+#include <bakery_lock.h>
+#include <stddef.h>
+#include <stdint.h>
+
+/* Supported SCMI Protocol Versions */
+#define SCMI_PWR_DMN_PROTO_VER			MAKE_SCMI_VERSION(1, 0)
+#define SCMI_SYS_PWR_PROTO_VER			MAKE_SCMI_VERSION(1, 0)
+
+#define GET_SCMI_MAJOR_VER(ver)			(((ver) >> 16) & 0xffff)
+#define GET_SCMI_MINOR_VER(ver)			((ver) & 0xffff)
+
+#define MAKE_SCMI_VERSION(maj, min)	\
+			((((maj) & 0xffff) << 16) | ((min) & 0xffff))
+
+/* Macro to check if the driver is compatible with the SCMI version reported */
+#define is_scmi_version_compatible(drv, scmi)				\
+	((GET_SCMI_MAJOR_VER(drv) == GET_SCMI_MAJOR_VER(scmi)) &&	\
+	(GET_SCMI_MINOR_VER(drv) <= GET_SCMI_MINOR_VER(scmi)))
+
+/* SCMI Protocol identifiers */
+#define SCMI_PWR_DMN_PROTO_ID			0x11
+#define SCMI_SYS_PWR_PROTO_ID			0x12
+
+/* Mandatory messages IDs for all SCMI protocols */
+#define SCMI_PROTO_VERSION_MSG			0x0
+#define SCMI_PROTO_ATTR_MSG			0x1
+#define SCMI_PROTO_MSG_ATTR_MSG			0x2
+
+/* SCMI power domain management protocol message IDs */
+#define SCMI_PWR_STATE_SET_MSG			0x4
+#define SCMI_PWR_STATE_GET_MSG			0x5
+
+/* SCMI system power management protocol message IDs */
+#define SCMI_SYS_PWR_STATE_SET_MSG		0x3
+#define SCMI_SYS_PWR_STATE_GET_MSG		0x4
+
+/* Helper macros for system power management protocol commands */
+
+/*
+ * Macros to describe the bit-fields of the `attribute` of system power domain
+ * protocol PROTOCOL_MSG_ATTRIBUTE message.
+ */
+#define SYS_PWR_ATTR_WARM_RESET_SHIFT		31
+#define SCMI_SYS_PWR_WARM_RESET_SUPPORTED	(1U << SYS_PWR_ATTR_WARM_RESET_SHIFT)
+
+#define SYS_PWR_ATTR_SUSPEND_SHIFT		30
+#define SCMI_SYS_PWR_SUSPEND_SUPPORTED		(1 << SYS_PWR_ATTR_SUSPEND_SHIFT)
+
+/*
+ * Macros to describe the bit-fields of the `flags` parameter of system power
+ * domain protocol SYSTEM_POWER_STATE_SET message.
+ */
+#define SYS_PWR_SET_GRACEFUL_REQ_SHIFT		0
+#define SCMI_SYS_PWR_GRACEFUL_REQ		(1 << SYS_PWR_SET_GRACEFUL_REQ_SHIFT)
+#define SCMI_SYS_PWR_FORCEFUL_REQ		(0 << SYS_PWR_SET_GRACEFUL_REQ_SHIFT)
+
+/*
+ * Macros to describe the `system_state` parameter of system power
+ * domain protocol SYSTEM_POWER_STATE_SET message.
+ */
+#define SCMI_SYS_PWR_SHUTDOWN			0x0
+#define SCMI_SYS_PWR_COLD_RESET			0x1
+#define SCMI_SYS_PWR_WARM_RESET			0x2
+#define SCMI_SYS_PWR_POWER_UP			0x3
+#define SCMI_SYS_PWR_SUSPEND			0x4
+
+/* SCMI Error code definitions */
+#define SCMI_E_QUEUED			1
+#define SCMI_E_SUCCESS			0
+#define SCMI_E_NOT_SUPPORTED		-1
+#define SCMI_E_INVALID_PARAM		-2
+#define SCMI_E_DENIED			-3
+#define SCMI_E_NOT_FOUND		-4
+#define SCMI_E_OUT_OF_RANGE		-5
+#define SCMI_E_BUSY			-6
+
+/*
+ * SCMI driver platform information. The details of the doorbell mechanism
+ * can be found in the SCMI specification.
+ */
+typedef struct scmi_channel_plat_info {
+	/* SCMI mailbox memory */
+	uintptr_t scmi_mbx_mem;
+	/* The door bell register address */
+	uintptr_t db_reg_addr;
+	/* The bit mask that need to be preserved when ringing doorbell */
+	uint32_t db_preserve_mask;
+	/* The bit mask that need to be set to ring doorbell */
+	uint32_t db_modify_mask;
+} scmi_channel_plat_info_t;
+
+/*
+ * Structure to represent an SCMI channel.
+ */
+typedef struct scmi_channel {
+	scmi_channel_plat_info_t *info;
+	 /* The lock for channel access */
+	bakery_lock_t *lock;
+	/* Indicate whether the channel is initialized */
+	int is_initialized;
+} scmi_channel_t;
+
+/* External Common API */
+void *scmi_init(scmi_channel_t *ch);
+int scmi_proto_msg_attr(void *p, uint32_t proto_id, uint32_t command_id,
+						uint32_t *attr);
+int scmi_proto_version(void *p, uint32_t proto_id, uint32_t *version);
+
+/*
+ * Power domain protocol commands. Refer to the SCMI specification for more
+ * details on these commands.
+ */
+int scmi_pwr_state_set(void *p, uint32_t domain_id, uint32_t scmi_pwr_state);
+int scmi_pwr_state_get(void *p, uint32_t domain_id, uint32_t *scmi_pwr_state);
+
+/*
+ * System power management protocol commands. Refer SCMI specification for more
+ * details on these commands.
+ */
+int scmi_sys_pwr_state_set(void *p, uint32_t flags, uint32_t system_state);
+int scmi_sys_pwr_state_get(void *p, uint32_t *system_state);
+
+#endif	/* __CSS_SCMI_H__ */

plat/arm/css/drivers/scmi/scmi_common.c

+/*
+ * Copyright (c) 2017, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <arch_helpers.h>
+#include <assert.h>
+#include <debug.h>
+#include "scmi.h"
+#include "scmi_private.h"
+
+/*
+ * Private helper function to get exclusive access to SCMI channel.
+ */
+void scmi_get_channel(scmi_channel_t *ch)
+{
+	assert(ch->lock);
+	bakery_lock_get(ch->lock);
+
+	/* Make sure any previous command has finished */
+	assert(SCMI_IS_CHANNEL_FREE(
+			((mailbox_mem_t *)(ch->info->scmi_mbx_mem))->status));
+}
+
+/*
+ * Private helper function to transfer ownership of channel from AP to SCP.
+ */
+void scmi_send_sync_command(scmi_channel_t *ch)
+{
+	mailbox_mem_t *mbx_mem = (mailbox_mem_t *)(ch->info->scmi_mbx_mem);
+
+	SCMI_MARK_CHANNEL_BUSY(mbx_mem->status);
+
+	/*
+	 * Ensure that any write to the SCMI payload area is seen by SCP before
+	 * we write to the doorbell register. If these 2 writes were reordered
+	 * by the CPU then SCP would read stale payload data
+	 */
+	dmbst();
+
+	SCMI_RING_DOORBELL(ch->info->db_reg_addr, ch->info->db_modify_mask,
+					ch->info->db_preserve_mask);
+
+	/*
+	 * Ensure that the write to the doorbell register is ordered prior to
+	 * checking whether the channel is free.
+	 */
+	dmbsy();
+
+	/* Wait for channel to be free */
+	while (!SCMI_IS_CHANNEL_FREE(mbx_mem->status))
+		;
+
+	/*
+	 * Ensure that any read to the SCMI payload area is done after reading
+	 * mailbox status. If these 2 reads were reordered then the CPU would
+	 * read invalid payload data
+	 */
+	dmbld();
+}
+
+/*
+ * Private helper function to release exclusive access to SCMI channel.
+ */
+void scmi_put_channel(scmi_channel_t *ch)
+{
+	/* Make sure any previous command has finished */
+	assert(SCMI_IS_CHANNEL_FREE(
+			((mailbox_mem_t *)(ch->info->scmi_mbx_mem))->status));
+
+	assert(ch->lock);
+	bakery_lock_release(ch->lock);
+}
+
+/*
+ * API to query the SCMI protocol version.
+ */
+int scmi_proto_version(void *p, uint32_t proto_id, uint32_t *version)
+{
+	mailbox_mem_t *mbx_mem;
+	int token = 0, ret;
+	scmi_channel_t *ch = (scmi_channel_t *)p;
+
+	validate_scmi_channel(ch);
+
+	scmi_get_channel(ch);
+
+	mbx_mem = (mailbox_mem_t *)(ch->info->scmi_mbx_mem);
+	mbx_mem->msg_header = SCMI_MSG_CREATE(proto_id, SCMI_PROTO_VERSION_MSG,
+							token);
+	mbx_mem->len = SCMI_PROTO_VERSION_MSG_LEN;
+	mbx_mem->flags = SCMI_FLAG_RESP_POLL;
+
+	scmi_send_sync_command(ch);
+
+	/* Get the return values */
+	SCMI_PAYLOAD_RET_VAL2(mbx_mem->payload, ret, *version);
+	assert(mbx_mem->len == SCMI_PROTO_VERSION_RESP_LEN);
+	assert(token == SCMI_MSG_GET_TOKEN(mbx_mem->msg_header));
+
+	scmi_put_channel(ch);
+
+	return ret;
+}
+
+/*
+ * API to query the protocol message attributes for a SCMI protocol.
+ */
+int scmi_proto_msg_attr(void *p, uint32_t proto_id,
+		uint32_t command_id, uint32_t *attr)
+{
+	mailbox_mem_t *mbx_mem;
+	int token = 0, ret;
+	scmi_channel_t *ch = (scmi_channel_t *)p;
+
+	validate_scmi_channel(ch);
+
+	scmi_get_channel(ch);
+
+	mbx_mem = (mailbox_mem_t *)(ch->info->scmi_mbx_mem);
+	mbx_mem->msg_header = SCMI_MSG_CREATE(proto_id,
+				SCMI_PROTO_MSG_ATTR_MSG, token);
+	mbx_mem->len = SCMI_PROTO_MSG_ATTR_MSG_LEN;
+	mbx_mem->flags = SCMI_FLAG_RESP_POLL;
+	SCMI_PAYLOAD_ARG1(mbx_mem->payload, command_id);
+
+	scmi_send_sync_command(ch);
+
+	/* Get the return values */
+	SCMI_PAYLOAD_RET_VAL2(mbx_mem->payload, ret, *attr);
+	assert(mbx_mem->len == SCMI_PROTO_MSG_ATTR_RESP_LEN);
+	assert(token == SCMI_MSG_GET_TOKEN(mbx_mem->msg_header));
+
+	scmi_put_channel(ch);
+
+	return ret;
+}
+
+/*
+ * SCMI Driver initialization API. Returns initialized channel on success
+ * or NULL on error. The return type is an opaque void pointer.
+ */
+void *scmi_init(scmi_channel_t *ch)
+{
+	uint32_t version;
+	int ret;
+
+	assert(ch && ch->info);
+	assert(ch->info->db_reg_addr);
+	assert(ch->info->db_modify_mask);
+	assert(ch->info->db_preserve_mask);
+
+	assert(ch->lock);
+
+	bakery_lock_init(ch->lock);
+
+	ch->is_initialized = 1;
+
+	ret = scmi_proto_version(ch, SCMI_PWR_DMN_PROTO_ID, &version);
+	if (ret != SCMI_E_SUCCESS) {
+		WARN("SCMI power domain protocol version message failed");
+		goto error;
+	}
+
+	if (!is_scmi_version_compatible(SCMI_PWR_DMN_PROTO_VER, version)) {
+		WARN("SCMI power domain protocol version 0x%x incompatible with driver version 0x%x",
+			version, SCMI_PWR_DMN_PROTO_VER);
+		goto error;
+	}
+
+	VERBOSE("SCMI power domain protocol version 0x%x detected\n", version);
+
+	ret = scmi_proto_version(ch, SCMI_SYS_PWR_PROTO_ID, &version);
+	if ((ret != SCMI_E_SUCCESS)) {
+		WARN("SCMI system power protocol version message failed");
+		goto error;
+	}
+
+	if (!is_scmi_version_compatible(SCMI_SYS_PWR_PROTO_VER, version)) {
+		WARN("SCMI system power management protocol version 0x%x incompatible with driver version 0x%x",
+			version, SCMI_SYS_PWR_PROTO_VER);
+		goto error;
+	}
+
+	VERBOSE("SCMI system power management protocol version 0x%x detected\n",
+						version);
+
+	INFO("SCMI driver initialized\n");
+
+	return (void *)ch;
+
+error:
+	ch->is_initialized = 0;
+	return NULL;
+}

plat/arm/css/drivers/scmi/scmi_private.h

+/*
+ * Copyright (c) 2017, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#ifndef __CSS_SCMI_PRIVATE_H__
+#define __CSS_SCMI_PRIVATE_H__
+
+/*
+ * SCMI power domain management protocol message and response lengths. It is
+ * calculated as sum of length in bytes of the message header (4) and payload
+ * area (the number of bytes of parameters or return values in the payload).
+ */
+#define SCMI_PROTO_VERSION_MSG_LEN		4
+#define SCMI_PROTO_VERSION_RESP_LEN		12
+
+#define SCMI_PROTO_MSG_ATTR_MSG_LEN		8
+#define SCMI_PROTO_MSG_ATTR_RESP_LEN		12
+
+#define SCMI_PWR_STATE_SET_MSG_LEN		16
+#define SCMI_PWR_STATE_SET_RESP_LEN		8
+
+#define SCMI_PWR_STATE_GET_MSG_LEN		8
+#define SCMI_PWR_STATE_GET_RESP_LEN		12
+
+#define SCMI_SYS_PWR_STATE_SET_MSG_LEN		12
+#define SCMI_SYS_PWR_STATE_SET_RESP_LEN		8
+
+#define SCMI_SYS_PWR_STATE_GET_MSG_LEN		4
+#define SCMI_SYS_PWR_STATE_GET_RESP_LEN		12
+
+/* SCMI message header format bit field */
+#define SCMI_MSG_ID_SHIFT		0
+#define SCMI_MSG_ID_WIDTH		8
+#define SCMI_MSG_ID_MASK		((1 << SCMI_MSG_ID_WIDTH) - 1)
+
+#define SCMI_MSG_TYPE_SHIFT		8
+#define SCMI_MSG_TYPE_WIDTH		2
+#define SCMI_MSG_TYPE_MASK		((1 << SCMI_MSG_TYPE_WIDTH) - 1)
+
+#define SCMI_MSG_PROTO_ID_SHIFT		10
+#define SCMI_MSG_PROTO_ID_WIDTH		8
+#define SCMI_MSG_PROTO_ID_MASK		((1 << SCMI_MSG_PROTO_ID_WIDTH) - 1)
+
+#define SCMI_MSG_TOKEN_SHIFT		18
+#define SCMI_MSG_TOKEN_WIDTH		10
+#define SCMI_MSG_TOKEN_MASK		((1 << SCMI_MSG_TOKEN_WIDTH) - 1)
+
+
+/* SCMI mailbox flags */
+#define SCMI_FLAG_RESP_POLL	0
+#define SCMI_FLAG_RESP_INT	1
+
+/* SCMI power domain protocol `POWER_STATE_SET` message flags */
+#define SCMI_PWR_STATE_SET_FLAG_SYNC	0
+#define SCMI_PWR_STATE_SET_FLAG_ASYNC	1
+
+/*
+ * Helper macro to create an SCMI message header given protocol, message id
+ * and token.
+ */
+#define SCMI_MSG_CREATE(protocol, msg_id, token)				\
+	((((protocol) & SCMI_MSG_PROTO_ID_MASK) << SCMI_MSG_PROTO_ID_SHIFT) |	\
+	(((msg_id) & SCMI_MSG_ID_MASK) << SCMI_MSG_ID_SHIFT) |			\
+	(((token) & SCMI_MSG_TOKEN_MASK) << SCMI_MSG_TOKEN_SHIFT))
+
+/* Helper macro to get the token from a SCMI message header */
+#define SCMI_MSG_GET_TOKEN(msg)				\
+	(((msg) >> SCMI_MSG_TOKEN_SHIFT) & SCMI_MSG_TOKEN_MASK)
+
+/* SCMI Channel Status bit fields */
+#define SCMI_CH_STATUS_RES0_MASK	0xFFFFFFFE
+#define SCMI_CH_STATUS_FREE_SHIFT	0
+#define SCMI_CH_STATUS_FREE_WIDTH	1
+#define SCMI_CH_STATUS_FREE_MASK	((1 << SCMI_CH_STATUS_FREE_WIDTH) - 1)
+
+/* Helper macros to check and write the channel status */
+#define SCMI_IS_CHANNEL_FREE(status)					\
+	(!!(((status) >> SCMI_CH_STATUS_FREE_SHIFT) & SCMI_CH_STATUS_FREE_MASK))
+
+#define SCMI_MARK_CHANNEL_BUSY(status)	do {				\
+		assert(SCMI_IS_CHANNEL_FREE(status));			\
+		(status) &= ~(SCMI_CH_STATUS_FREE_MASK <<		\
+				SCMI_CH_STATUS_FREE_SHIFT);		\
+	} while (0)
+
+/* Helper macros to copy arguments to the mailbox payload */
+#define SCMI_PAYLOAD_ARG1(payld_arr, arg1)				\
+		mmio_write_32((uintptr_t)&payld_arr[0], arg1)
+
+#define SCMI_PAYLOAD_ARG2(payld_arr, arg1, arg2)	do {		\
+		SCMI_PAYLOAD_ARG1(payld_arr, arg1);			\
+		mmio_write_32((uintptr_t)&payld_arr[1], arg2);		\
+	} while (0)
+
+#define SCMI_PAYLOAD_ARG3(payld_arr, arg1, arg2, arg3)	do {		\
+		SCMI_PAYLOAD_ARG2(payld_arr, arg1, arg2);		\
+		mmio_write_32((uintptr_t)&payld_arr[2], arg3);		\
+	} while (0)
+
+/* Helper macros to read return values from the mailbox payload */
+#define SCMI_PAYLOAD_RET_VAL1(payld_arr, val1)				\
+		(val1) = mmio_read_32((uintptr_t)&payld_arr[0])
+
+#define SCMI_PAYLOAD_RET_VAL2(payld_arr, val1, val2)	do {		\
+		SCMI_PAYLOAD_RET_VAL1(payld_arr, val1);			\
+		(val2) = mmio_read_32((uintptr_t)&payld_arr[1]);	\
+	} while (0)
+
+#define SCMI_PAYLOAD_RET_VAL3(payld_arr, val1, val2, val3)	do {	\
+		SCMI_PAYLOAD_RET_VAL2(payld_arr, val1, val2);		\
+		(val3) = mmio_read_32((uintptr_t)&payld_arr[2]);	\
+	} while (0)
+
+/* Helper macro to ring doorbell */
+#define SCMI_RING_DOORBELL(addr, modify_mask, preserve_mask)	do {	\
+		uint32_t db = mmio_read_32(addr) & (preserve_mask);	\
+		mmio_write_32(addr, db | (modify_mask));		\
+	} while (0)
+
+/*
+ * Private data structure for representing the mailbox memory layout. Refer
+ * the SCMI specification for more details.
+ */
+typedef struct mailbox_mem {
+	uint32_t res_a; /* Reserved */
+	volatile uint32_t status;
+	uint64_t res_b; /* Reserved */
+	uint32_t flags;
+	volatile uint32_t len;
+	uint32_t msg_header;
+	uint32_t payload[];
+} mailbox_mem_t;
+
+
+/* Private APIs for use within SCMI driver */
+void scmi_get_channel(scmi_channel_t *ch);
+void scmi_send_sync_command(scmi_channel_t *ch);
+void scmi_put_channel(scmi_channel_t *ch);
+
+static inline void validate_scmi_channel(scmi_channel_t *ch)
+{
+	assert(ch && ch->is_initialized);
+	assert(ch->info && ch->info->scmi_mbx_mem);
+}
+
+#endif	/* __CSS_SCMI_PRIVATE_H__ */

plat/arm/css/drivers/scmi/scmi_pwr_dmn_proto.c

+/*
+ * Copyright (c) 2017, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <arch_helpers.h>
+#include <assert.h>
+#include <debug.h>
+#include "scmi.h"
+#include "scmi_private.h"
+
+/*
+ * API to set the SCMI power domain power state.
+ */
+int scmi_pwr_state_set(void *p, uint32_t domain_id,
+					uint32_t scmi_pwr_state)
+{
+	mailbox_mem_t *mbx_mem;
+	int token = 0, ret;
+
+	/*
+	 * Only asynchronous mode of `set power state` command is allowed on
+	 * application processors.
+	 */
+	uint32_t pwr_state_set_msg_flag = SCMI_PWR_STATE_SET_FLAG_ASYNC;
+	scmi_channel_t *ch = (scmi_channel_t *)p;
+
+	validate_scmi_channel(ch);
+
+	scmi_get_channel(ch);
+
+	mbx_mem = (mailbox_mem_t *)(ch->info->scmi_mbx_mem);
+	mbx_mem->msg_header = SCMI_MSG_CREATE(SCMI_PWR_DMN_PROTO_ID,
+			SCMI_PWR_STATE_SET_MSG, token);
+	mbx_mem->len = SCMI_PWR_STATE_SET_MSG_LEN;
+	mbx_mem->flags = SCMI_FLAG_RESP_POLL;
+	SCMI_PAYLOAD_ARG3(mbx_mem->payload, pwr_state_set_msg_flag,
+						domain_id, scmi_pwr_state);
+
+	scmi_send_sync_command(ch);
+
+	/* Get the return values */
+	SCMI_PAYLOAD_RET_VAL1(mbx_mem->payload, ret);
+	assert(mbx_mem->len == SCMI_PWR_STATE_SET_RESP_LEN);
+	assert(token == SCMI_MSG_GET_TOKEN(mbx_mem->msg_header));
+
+	scmi_put_channel(ch);
+
+	return ret;
+}
+
+/*
+ * API to get the SCMI power domain power state.
+ */
+int scmi_pwr_state_get(void *p, uint32_t domain_id,
+					uint32_t *scmi_pwr_state)
+{
+	mailbox_mem_t *mbx_mem;
+	int token = 0, ret;
+	scmi_channel_t *ch = (scmi_channel_t *)p;
+
+	validate_scmi_channel(ch);
+
+	scmi_get_channel(ch);
+
+	mbx_mem = (mailbox_mem_t *)(ch->info->scmi_mbx_mem);
+	mbx_mem->msg_header = SCMI_MSG_CREATE(SCMI_PWR_DMN_PROTO_ID,
+			SCMI_PWR_STATE_GET_MSG, token);
+	mbx_mem->len = SCMI_PWR_STATE_GET_MSG_LEN;
+	mbx_mem->flags = SCMI_FLAG_RESP_POLL;
+	SCMI_PAYLOAD_ARG1(mbx_mem->payload, domain_id);
+
+	scmi_send_sync_command(ch);
+
+	/* Get the return values */
+	SCMI_PAYLOAD_RET_VAL2(mbx_mem->payload, ret, *scmi_pwr_state);
+	assert(mbx_mem->len == SCMI_PWR_STATE_GET_RESP_LEN);
+	assert(token == SCMI_MSG_GET_TOKEN(mbx_mem->msg_header));
+
+	scmi_put_channel(ch);
+
+	return ret;
+}

plat/arm/css/drivers/scmi/scmi_sys_pwr_proto.c

+/*
+ * Copyright (c) 2017, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <arch_helpers.h>
+#include <assert.h>
+#include <debug.h>
+#include "scmi.h"
+#include "scmi_private.h"
+
+/*
+ * API to set the SCMI system power state
+ */
+int scmi_sys_pwr_state_set(void *p, uint32_t flags, uint32_t system_state)
+{
+	mailbox_mem_t *mbx_mem;
+	int token = 0, ret;
+	scmi_channel_t *ch = (scmi_channel_t *)p;
+
+	validate_scmi_channel(ch);
+
+	scmi_get_channel(ch);
+
+	mbx_mem = (mailbox_mem_t *)(ch->info->scmi_mbx_mem);
+	mbx_mem->msg_header = SCMI_MSG_CREATE(SCMI_SYS_PWR_PROTO_ID,
+			SCMI_SYS_PWR_STATE_SET_MSG, token);
+	mbx_mem->len = SCMI_SYS_PWR_STATE_SET_MSG_LEN;
+	mbx_mem->flags = SCMI_FLAG_RESP_POLL;
+	SCMI_PAYLOAD_ARG2(mbx_mem->payload, flags, system_state);
+
+	scmi_send_sync_command(ch);
+
+	/* Get the return values */
+	SCMI_PAYLOAD_RET_VAL1(mbx_mem->payload, ret);
+	assert(mbx_mem->len == SCMI_SYS_PWR_STATE_SET_RESP_LEN);
+	assert(token == SCMI_MSG_GET_TOKEN(mbx_mem->msg_header));
+
+	scmi_put_channel(ch);
+
+	return ret;
+}
+
+/*
+ * API to get the SCMI system power state
+ */
+int scmi_sys_pwr_state_get(void *p, uint32_t *system_state)
+{
+	mailbox_mem_t *mbx_mem;
+	int token = 0, ret;
+	scmi_channel_t *ch = (scmi_channel_t *)p;
+
+	validate_scmi_channel(ch);
+
+	scmi_get_channel(ch);
+
+	mbx_mem = (mailbox_mem_t *)(ch->info->scmi_mbx_mem);
+	mbx_mem->msg_header = SCMI_MSG_CREATE(SCMI_SYS_PWR_PROTO_ID,
+			SCMI_SYS_PWR_STATE_GET_MSG, token);
+	mbx_mem->len = SCMI_SYS_PWR_STATE_GET_MSG_LEN;
+	mbx_mem->flags = SCMI_FLAG_RESP_POLL;
+
+	scmi_send_sync_command(ch);
+
+	/* Get the return values */
+	SCMI_PAYLOAD_RET_VAL2(mbx_mem->payload, ret, *system_state);
+	assert(mbx_mem->len == SCMI_SYS_PWR_STATE_GET_RESP_LEN);
+	assert(token == SCMI_MSG_GET_TOKEN(mbx_mem->msg_header));
+
+	scmi_put_channel(ch);
+
+	return ret;
+}

plat/arm/css/drivers/scp/css_pm_scmi.c

+/*
+ * Copyright (c) 2017, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <arch_helpers.h>
+#include <assert.h>
+#include <css_def.h>
+#include <css_pm.h>
+#include <debug.h>
+#include <plat_arm.h>
+#include <platform.h>
+#include <string.h>
+#include "../scmi/scmi.h"
+#include "css_scp.h"
+
+/*
+ * This file implements the SCP helper functions using SCMI protocol.
+ */
+
+/*
+ * SCMI power state parameter bit field encoding for ARM CSS platforms.
+ *
+ * 31  20 19       16 15      12 11       8 7        4 3         0
+ * +-------------------------------------------------------------+
+ * | SBZ | Max level |  Level 3 |  Level 2 |  Level 1 |  Level 0 |
+ * |     |           |   state  |   state  |   state  |   state  |
+ * +-------------------------------------------------------------+
+ *
+ * `Max level` encodes the highest level that has a valid power state
+ * encoded in the power state.
+ */
+#define SCMI_PWR_STATE_MAX_PWR_LVL_SHIFT	16
+#define SCMI_PWR_STATE_MAX_PWR_LVL_WIDTH	4
+#define SCMI_PWR_STATE_MAX_PWR_LVL_MASK		\
+				((1 << SCMI_PWR_STATE_MAX_PWR_LVL_WIDTH) - 1)
+#define SCMI_SET_PWR_STATE_MAX_PWR_LVL(pwr_state, max_lvl)		\
+		(pwr_state) |= ((max_lvl) & SCMI_PWR_STATE_MAX_PWR_LVL_MASK)	\
+				<< SCMI_PWR_STATE_MAX_PWR_LVL_SHIFT
+#define SCMI_GET_PWR_STATE_MAX_PWR_LVL(pwr_state)		\
+		(((pwr_state) >> SCMI_PWR_STATE_MAX_PWR_LVL_SHIFT)	\
+				& SCMI_PWR_STATE_MAX_PWR_LVL_MASK)
+
+#define SCMI_PWR_STATE_LVL_WIDTH		4
+#define SCMI_PWR_STATE_LVL_MASK			\
+				((1 << SCMI_PWR_STATE_LVL_WIDTH) - 1)
+#define SCMI_SET_PWR_STATE_LVL(pwr_state, lvl, lvl_state)		\
+		(pwr_state) |= ((lvl_state) & SCMI_PWR_STATE_LVL_MASK)	\
+				<< (SCMI_PWR_STATE_LVL_WIDTH * (lvl))
+#define SCMI_GET_PWR_STATE_LVL(pwr_state, lvl)		\
+		(((pwr_state) >> (SCMI_PWR_STATE_LVL_WIDTH * (lvl))) &	\
+				SCMI_PWR_STATE_LVL_MASK)
+
+/*
+ * The SCMI power state enumeration for a power domain level
+ */
+typedef enum {
+	scmi_power_state_off = 0,
+	scmi_power_state_on = 1,
+	scmi_power_state_sleep = 2,
+} scmi_power_state_t;
+
+/*
+ * This mapping array has to be exported by the platform. Each element at
+ * a given index maps that core to an SCMI power domain.
+ */
+extern uint32_t plat_css_core_pos_to_scmi_dmn_id_map[];
+
+/*
+ * The global handle for invoking the SCMI driver APIs after the driver
+ * has been initialized.
+ */
+void *scmi_handle;
+
+/* The SCMI channel global object */
+static scmi_channel_t scmi_channel;
+
+ARM_INSTANTIATE_LOCK
+
+/*
+ * Helper function to suspend a CPU power domain and its parent power domains
+ * if applicable.
+ */
+void css_scp_suspend(const psci_power_state_t *target_state)
+{
+	int lvl, ret;
+	uint32_t scmi_pwr_state = 0;
+
+	/* At least power domain level 0 should be specified to be suspended */
+	assert(target_state->pwr_domain_state[ARM_PWR_LVL0] ==
+						ARM_LOCAL_STATE_OFF);
+
+	/* Check if power down at system power domain level is requested */
+	if (CSS_SYSTEM_PWR_STATE(target_state) == ARM_LOCAL_STATE_OFF) {
+		/* Issue SCMI command for SYSTEM_SUSPEND */
+		ret = scmi_sys_pwr_state_set(scmi_handle,
+				SCMI_SYS_PWR_FORCEFUL_REQ,
+				SCMI_SYS_PWR_SUSPEND);
+		if (ret != SCMI_E_SUCCESS) {
+			ERROR("SCMI system power domain suspend return 0x%x unexpected\n",
+					ret);
+			panic();
+		}
+		return;
+	}
+
+	/*
+	 * If we reach here, then assert that power down at system power domain
+	 * level is running.
+	 */
+	assert(target_state->pwr_domain_state[CSS_SYSTEM_PWR_DMN_LVL] ==
+							ARM_LOCAL_STATE_RUN);
+
+	/* For level 0, specify `scmi_power_state_sleep` as the power state */
+	SCMI_SET_PWR_STATE_LVL(scmi_pwr_state, ARM_PWR_LVL0,
+						scmi_power_state_sleep);
+
+	for (lvl = ARM_PWR_LVL1; lvl <= PLAT_MAX_PWR_LVL; lvl++) {
+		if (target_state->pwr_domain_state[lvl] == ARM_LOCAL_STATE_RUN)
+			break;
+
+		assert(target_state->pwr_domain_state[lvl] ==
+							ARM_LOCAL_STATE_OFF);
+		/*
+		 * Specify `scmi_power_state_off` as power state for higher
+		 * levels.
+		 */
+		SCMI_SET_PWR_STATE_LVL(scmi_pwr_state, lvl,
+						scmi_power_state_off);
+	}
+
+	SCMI_SET_PWR_STATE_MAX_PWR_LVL(scmi_pwr_state, lvl - 1);
+
+	ret = scmi_pwr_state_set(scmi_handle,
+		plat_css_core_pos_to_scmi_dmn_id_map[plat_my_core_pos()],
+		scmi_pwr_state);
+
+	if (ret != SCMI_E_SUCCESS) {
+		ERROR("SCMI set power state command return 0x%x unexpected\n",
+				ret);
+		panic();
+	}
+}
+
+/*
+ * Helper function to turn off a CPU power domain and its parent power domains
+ * if applicable.
+ */
+void css_scp_off(const psci_power_state_t *target_state)
+{
+	int lvl = 0, ret;
+	uint32_t scmi_pwr_state = 0;
+
+	/* At-least the CPU level should be specified to be OFF */
+	assert(target_state->pwr_domain_state[ARM_PWR_LVL0] ==
+							ARM_LOCAL_STATE_OFF);
+
+	/* PSCI CPU OFF cannot be used to turn OFF system power domain */
+	assert(target_state->pwr_domain_state[CSS_SYSTEM_PWR_DMN_LVL] ==
+							ARM_LOCAL_STATE_RUN);
+
+	for (; lvl <= PLAT_MAX_PWR_LVL; lvl++) {
+		if (target_state->pwr_domain_state[lvl] == ARM_LOCAL_STATE_RUN)
+			break;
+
+		assert(target_state->pwr_domain_state[lvl] ==
+							ARM_LOCAL_STATE_OFF);
+		SCMI_SET_PWR_STATE_LVL(scmi_pwr_state, lvl,
+				scmi_power_state_off);
+	}
+
+	SCMI_SET_PWR_STATE_MAX_PWR_LVL(scmi_pwr_state, lvl - 1);
+
+	ret = scmi_pwr_state_set(scmi_handle,
+		plat_css_core_pos_to_scmi_dmn_id_map[plat_my_core_pos()],
+		scmi_pwr_state);
+
+	if (ret != SCMI_E_QUEUED && ret != SCMI_E_SUCCESS) {
+		ERROR("SCMI set power state command return 0x%x unexpected\n",
+				ret);
+		panic();
+	}
+}
+
+/*
+ * Helper function to turn ON a CPU power domain and its parent power domains
+ * if applicable.
+ */
+void css_scp_on(u_register_t mpidr)
+{
+	int lvl = 0, ret;
+	uint32_t scmi_pwr_state = 0;
+
+	for (; lvl <= PLAT_MAX_PWR_LVL; lvl++)
+		SCMI_SET_PWR_STATE_LVL(scmi_pwr_state, lvl,
+				scmi_power_state_on);
+
+	SCMI_SET_PWR_STATE_MAX_PWR_LVL(scmi_pwr_state, lvl - 1);
+
+	ret = scmi_pwr_state_set(scmi_handle,
+		plat_css_core_pos_to_scmi_dmn_id_map[plat_core_pos_by_mpidr(mpidr)],
+		scmi_pwr_state);
+
+	if (ret != SCMI_E_QUEUED && ret != SCMI_E_SUCCESS) {
+		ERROR("SCMI set power state command return 0x%x unexpected\n",
+				ret);
+		panic();
+	}
+}
+
+/*
+ * Helper function to get the power state of a power domain node as reported
+ * by the SCP.
+ */
+int css_scp_get_power_state(u_register_t mpidr, unsigned int power_level)
+{
+	int ret, cpu_idx;
+	uint32_t scmi_pwr_state = 0, lvl_state;
+
+	/* We don't support get power state at the system power domain level */
+	if ((power_level > PLAT_MAX_PWR_LVL) ||
+			(power_level == CSS_SYSTEM_PWR_DMN_LVL)) {
+		WARN("Invalid power level %u specified for SCMI get power state\n",
+				power_level);
+		return PSCI_E_INVALID_PARAMS;
+	}
+
+	cpu_idx = plat_core_pos_by_mpidr(mpidr);
+	assert(cpu_idx > -1);
+
+	ret = scmi_pwr_state_get(scmi_handle,
+		plat_css_core_pos_to_scmi_dmn_id_map[cpu_idx],
+		&scmi_pwr_state);
+
+	if (ret != SCMI_E_SUCCESS) {
+		WARN("SCMI get power state command return 0x%x unexpected\n",
+				ret);
+		return PSCI_E_INVALID_PARAMS;
+	}
+
+	/*
+	 * Find the maximum power level described in the get power state
+	 * command. If it is less than the requested power level, then assume
+	 * the requested power level is ON.
+	 */
+	if (SCMI_GET_PWR_STATE_MAX_PWR_LVL(scmi_pwr_state) < power_level)
+		return HW_ON;
+
+	lvl_state = SCMI_GET_PWR_STATE_LVL(scmi_pwr_state, power_level);
+	if (lvl_state == scmi_power_state_on)
+		return HW_ON;
+
+	assert((lvl_state == scmi_power_state_off) ||
+				(lvl_state == scmi_power_state_sleep));
+	return HW_OFF;
+}
+
+/*
+ * Helper function to shutdown the system via SCMI.
+ */
+void __dead2 css_scp_sys_shutdown(void)
+{
+	int ret;
+
+	/*
+	 * Disable GIC CPU interface to prevent pending interrupt from waking
+	 * up the AP from WFI.
+	 */
+	plat_arm_gic_cpuif_disable();
+
+	/*
+	 * Issue SCMI command for SYSTEM_SHUTDOWN. First issue a graceful
+	 * request and if that fails force the request.
+	 */
+	ret = scmi_sys_pwr_state_set(scmi_handle,
+			SCMI_SYS_PWR_FORCEFUL_REQ,
+			SCMI_SYS_PWR_SHUTDOWN);
+	if (ret != SCMI_E_SUCCESS) {
+		ERROR("SCMI system power domain shutdown return 0x%x unexpected\n",
+				ret);
+		panic();
+	}
+
+	wfi();
+	ERROR("CSS System Shutdown: operation not handled.\n");
+	panic();
+}
+
+/*
+ * Helper function to reset the system via SCMI.
+ */
+void __dead2 css_scp_sys_reboot(void)
+{
+	int ret;
+
+	/*
+	 * Disable GIC CPU interface to prevent pending interrupt from waking
+	 * up the AP from WFI.
+	 */
+	plat_arm_gic_cpuif_disable();
+
+	/*
+	 * Issue SCMI command for SYSTEM_REBOOT. First issue a graceful
+	 * request and if that fails force the request.
+	 */
+	ret = scmi_sys_pwr_state_set(scmi_handle,
+			SCMI_SYS_PWR_FORCEFUL_REQ,
+			SCMI_SYS_PWR_COLD_RESET);
+	if (ret != SCMI_E_SUCCESS) {
+		ERROR("SCMI system power domain reset return 0x%x unexpected\n",
+				ret);
+		panic();
+	}
+
+	wfi();
+	ERROR("CSS System Reset: operation not handled.\n");
+	panic();
+}
+
+scmi_channel_plat_info_t plat_css_scmi_plat_info = {
+		.scmi_mbx_mem = CSS_SCMI_PAYLOAD_BASE,
+		.db_reg_addr = PLAT_CSS_MHU_BASE + CSS_SCMI_MHU_DB_REG_OFF,
+		.db_preserve_mask = 0xfffffffd,
+		.db_modify_mask = 0x2,
+};
+
+void plat_arm_pwrc_setup(void)
+{
+	scmi_channel.info = &plat_css_scmi_plat_info;
+	scmi_channel.lock = ARM_LOCK_GET_INSTANCE;
+	scmi_handle = scmi_init(&scmi_channel);
+	if (scmi_handle == NULL) {
+		ERROR("SCMI Initialization failed\n");
+		panic();
+	}
+}
+
+/******************************************************************************
+ * This function overrides the default definition for ARM platforms. Initialize
+ * the SCMI driver, query capability via SCMI and modify the PSCI capability
+ * based on that.
+ *****************************************************************************/
+const plat_psci_ops_t *plat_arm_psci_override_pm_ops(plat_psci_ops_t *ops)
+{
+	uint32_t msg_attr;
+	int ret;
+
+	assert(scmi_handle);
+
+	/* Check that power domain POWER_STATE_SET message is supported */
+	ret = scmi_proto_msg_attr(scmi_handle, SCMI_PWR_DMN_PROTO_ID,
+				SCMI_PWR_STATE_SET_MSG, &msg_attr);
+	if (ret != SCMI_E_SUCCESS) {
+		ERROR("Set power state command is not supported by SCMI\n");
+		panic();
+	}
+
+	/*
+	 * Don't support PSCI NODE_HW_STATE call if SCMI doesn't support
+	 * POWER_STATE_GET message.
+	 */
+	ret = scmi_proto_msg_attr(scmi_handle, SCMI_PWR_DMN_PROTO_ID,
+				SCMI_PWR_STATE_GET_MSG, &msg_attr);
+	if (ret != SCMI_E_SUCCESS)
+		ops->get_node_hw_state = NULL;
+
+	/* Check if the SCMI SYSTEM_POWER_STATE_SET message is supported */
+	ret = scmi_proto_msg_attr(scmi_handle, SCMI_SYS_PWR_PROTO_ID,
+				SCMI_SYS_PWR_STATE_SET_MSG, &msg_attr);
+	if (ret != SCMI_E_SUCCESS) {
+		/* System power management operations are not supported */
+		ops->system_off = NULL;
+		ops->system_reset = NULL;
+		ops->get_sys_suspend_power_state = NULL;
+	} else if (!(msg_attr & SCMI_SYS_PWR_SUSPEND_SUPPORTED)) {
+		/*
+		 * System power management protocol is available, but it does
+		 * not support SYSTEM SUSPEND.
+		 */
+		ops->get_sys_suspend_power_state = NULL;
+	}
+
+	return ops;
+}