Adding upstream version 2.10.0+dfsg.upstream/2.10.0+dfsgupstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

18 files changed, 2552 insertions, 0 deletions

diff --git a/drivers/arm/css/mhu/css_mhu.c b/drivers/arm/css/mhu/css_mhu.c
new file mode 100644
index 0000000..b7faf7e
--- /dev/null
+++ b/drivers/arm/css/mhu/css_mhu.c
@@ -0,0 +1,100 @@
+/*
+ * Copyright (c) 2014-2018, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <assert.h>
+
+#include <platform_def.h>
+
+#include <arch_helpers.h>
+#include <drivers/arm/css/css_mhu.h>
+#include <lib/bakery_lock.h>
+#include <lib/mmio.h>
+#include <plat/arm/common/plat_arm.h>
+
+/* SCP MHU secure channel registers */
+#define SCP_INTR_S_STAT		0x200
+#define SCP_INTR_S_SET		0x208
+#define SCP_INTR_S_CLEAR	0x210
+
+/* CPU MHU secure channel registers */
+#define CPU_INTR_S_STAT		0x300
+#define CPU_INTR_S_SET		0x308
+#define CPU_INTR_S_CLEAR	0x310
+
+ARM_INSTANTIATE_LOCK;
+
+/* Weak definition may be overridden in specific CSS based platform */
+#pragma weak plat_arm_pwrc_setup
+
+
+/*
+ * Slot 31 is reserved because the MHU hardware uses this register bit to
+ * indicate a non-secure access attempt. The total number of available slots is
+ * therefore 31 [30:0].
+ */
+#define MHU_MAX_SLOT_ID		30
+
+void mhu_secure_message_start(unsigned int slot_id)
+{
+	assert(slot_id <= MHU_MAX_SLOT_ID);
+
+	arm_lock_get();
+
+	/* Make sure any previous command has finished */
+	while (mmio_read_32(PLAT_CSS_MHU_BASE + CPU_INTR_S_STAT) &
+							(1 << slot_id))
+		;
+}
+
+void mhu_secure_message_send(unsigned int slot_id)
+{
+	assert(slot_id <= MHU_MAX_SLOT_ID);
+	assert(!(mmio_read_32(PLAT_CSS_MHU_BASE + CPU_INTR_S_STAT) &
+							(1 << slot_id)));
+
+	/* Send command to SCP */
+	mmio_write_32(PLAT_CSS_MHU_BASE + CPU_INTR_S_SET, 1 << slot_id);
+}
+
+uint32_t mhu_secure_message_wait(void)
+{
+	/* Wait for response from SCP */
+	uint32_t response;
+	while (!(response = mmio_read_32(PLAT_CSS_MHU_BASE + SCP_INTR_S_STAT)))
+		;
+
+	return response;
+}
+
+void mhu_secure_message_end(unsigned int slot_id)
+{
+	assert(slot_id <= MHU_MAX_SLOT_ID);
+
+	/*
+	 * Clear any response we got by writing one in the relevant slot bit to
+	 * the CLEAR register
+	 */
+	mmio_write_32(PLAT_CSS_MHU_BASE + SCP_INTR_S_CLEAR, 1 << slot_id);
+
+	arm_lock_release();
+}
+
+void __init mhu_secure_init(void)
+{
+	arm_lock_init();
+
+	/*
+	 * The STAT register resets to zero. Ensure it is in the expected state,
+	 * as a stale or garbage value would make us think it's a message we've
+	 * already sent.
+	 */
+	assert(mmio_read_32(PLAT_CSS_MHU_BASE + CPU_INTR_S_STAT) == 0);
+}
+
+void __init plat_arm_pwrc_setup(void)
+{
+	mhu_secure_init();
+}
diff --git a/drivers/arm/css/mhu/css_mhu_doorbell.c b/drivers/arm/css/mhu/css_mhu_doorbell.c
new file mode 100644
index 0000000..479bb21
--- /dev/null
+++ b/drivers/arm/css/mhu/css_mhu_doorbell.c
@@ -0,0 +1,37 @@
+/*
+ * Copyright (c) 2014-2020, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <platform_def.h>
+
+#include <arch_helpers.h>
+#include <drivers/arm/css/css_mhu_doorbell.h>
+#include <drivers/arm/css/scmi.h>
+
+void mhu_ring_doorbell(struct scmi_channel_plat_info *plat_info)
+{
+	MHU_RING_DOORBELL(plat_info->db_reg_addr,
+			plat_info->db_modify_mask,
+			plat_info->db_preserve_mask);
+}
+
+void mhuv2_ring_doorbell(struct scmi_channel_plat_info *plat_info)
+{
+	uintptr_t mhuv2_base = plat_info->db_reg_addr & MHU_V2_FRAME_BASE_MASK;
+
+	/* wake receiver */
+	MHU_V2_ACCESS_REQUEST(mhuv2_base);
+
+	/* wait for receiver to acknowledge its ready */
+	while (MHU_V2_IS_ACCESS_READY(mhuv2_base) == 0)
+		;
+
+	MHU_RING_DOORBELL(plat_info->db_reg_addr,
+			plat_info->db_modify_mask,
+			plat_info->db_preserve_mask);
+
+	/* clear the access request for the receiver */
+	MHU_V2_CLEAR_REQUEST(mhuv2_base);
+}
diff --git a/drivers/arm/css/scmi/scmi_ap_core_proto.c b/drivers/arm/css/scmi/scmi_ap_core_proto.c
new file mode 100644
index 0000000..5941b87
--- /dev/null
+++ b/drivers/arm/css/scmi/scmi_ap_core_proto.c
@@ -0,0 +1,81 @@
+/*
+ * Copyright (c) 2018-2019, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <assert.h>
+
+#include <arch_helpers.h>
+#include <common/debug.h>
+#include <drivers/arm/css/scmi.h>
+
+#include "scmi_private.h"
+
+/*
+ * API to set the SCMI AP core reset address and attributes
+ */
+int scmi_ap_core_set_reset_addr(void *p, uint64_t reset_addr, uint32_t attr)
+{
+	mailbox_mem_t *mbx_mem;
+	unsigned int token = 0;
+	int 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_AP_CORE_PROTO_ID,
+			SCMI_AP_CORE_RESET_ADDR_SET_MSG, token);
+	mbx_mem->len = SCMI_AP_CORE_RESET_ADDR_SET_MSG_LEN;
+	mbx_mem->flags = SCMI_FLAG_RESP_POLL;
+	SCMI_PAYLOAD_ARG3(mbx_mem->payload, reset_addr & 0xffffffff,
+		reset_addr >> 32, attr);
+
+	scmi_send_sync_command(ch);
+
+	/* Get the return values */
+	SCMI_PAYLOAD_RET_VAL1(mbx_mem->payload, ret);
+	assert(mbx_mem->len == SCMI_AP_CORE_RESET_ADDR_SET_RESP_LEN);
+	assert(token == SCMI_MSG_GET_TOKEN(mbx_mem->msg_header));
+
+	scmi_put_channel(ch);
+
+	return ret;
+}
+
+/*
+ * API to get the SCMI AP core reset address and attributes
+ */
+int scmi_ap_core_get_reset_addr(void *p, uint64_t *reset_addr, uint32_t *attr)
+{
+	mailbox_mem_t *mbx_mem;
+	unsigned int token = 0;
+	int ret;
+	scmi_channel_t *ch = (scmi_channel_t *)p;
+	uint32_t lo_addr, hi_addr;
+
+	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_AP_CORE_PROTO_ID,
+			SCMI_AP_CORE_RESET_ADDR_GET_MSG, token);
+	mbx_mem->len = SCMI_AP_CORE_RESET_ADDR_GET_MSG_LEN;
+	mbx_mem->flags = SCMI_FLAG_RESP_POLL;
+
+	scmi_send_sync_command(ch);
+
+	/* Get the return values */
+	SCMI_PAYLOAD_RET_VAL4(mbx_mem->payload, ret, lo_addr, hi_addr, *attr);
+	*reset_addr = lo_addr | (uint64_t)hi_addr << 32;
+	assert(mbx_mem->len == SCMI_AP_CORE_RESET_ADDR_GET_RESP_LEN);
+	assert(token == SCMI_MSG_GET_TOKEN(mbx_mem->msg_header));
+
+	scmi_put_channel(ch);
+
+	return ret;
+}
diff --git a/drivers/arm/css/scmi/scmi_common.c b/drivers/arm/css/scmi/scmi_common.c
new file mode 100644
index 0000000..ec749fb
--- /dev/null
+++ b/drivers/arm/css/scmi/scmi_common.c
@@ -0,0 +1,210 @@
+/*
+ * Copyright (c) 2017-2019, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <assert.h>
+
+#include <arch_helpers.h>
+#include <common/debug.h>
+#include <drivers/arm/css/scmi.h>
+
+#include "scmi_private.h"
+
+#if HW_ASSISTED_COHERENCY
+#define scmi_lock_init(lock)
+#define scmi_lock_get(lock)		spin_lock(lock)
+#define scmi_lock_release(lock)		spin_unlock(lock)
+#else
+#define scmi_lock_init(lock)		bakery_lock_init(lock)
+#define scmi_lock_get(lock)		bakery_lock_get(lock)
+#define scmi_lock_release(lock)		bakery_lock_release(lock)
+#endif
+
+
+/*
+ * Private helper function to get exclusive access to SCMI channel.
+ */
+void scmi_get_channel(scmi_channel_t *ch)
+{
+	assert(ch->lock);
+	scmi_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();
+
+	ch->info->ring_doorbell(ch->info);
+	/*
+	 * 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);
+	scmi_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;
+	unsigned int token = 0;
+	int 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;
+	unsigned int token = 0;
+	int 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->info->ring_doorbell != NULL);
+
+	assert(ch->lock);
+
+	scmi_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\n");
+		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\n",
+			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\n");
+		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\n",
+			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;
+}
diff --git a/drivers/arm/css/scmi/scmi_private.h b/drivers/arm/css/scmi/scmi_private.h
new file mode 100644
index 0000000..a684ca5
--- /dev/null
+++ b/drivers/arm/css/scmi/scmi_private.h
@@ -0,0 +1,160 @@
+/*
+ * Copyright (c) 2017-2018, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#ifndef SCMI_PRIVATE_H
+#define SCMI_PRIVATE_H
+
+#include <lib/mmio.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_AP_CORE_RESET_ADDR_SET_MSG_LEN	16
+#define SCMI_AP_CORE_RESET_ADDR_SET_RESP_LEN	8
+
+#define SCMI_AP_CORE_RESET_ADDR_GET_MSG_LEN	4
+#define SCMI_AP_CORE_RESET_ADDR_GET_RESP_LEN	20
+
+#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)
+
+#define SCMI_PAYLOAD_RET_VAL4(payld_arr, val1, val2, val3, val4)	do {	\
+		SCMI_PAYLOAD_RET_VAL3(payld_arr, val1, val2, val3);		\
+		(val4) = mmio_read_32((uintptr_t)&payld_arr[3]);		\
+	} 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;
+	volatile 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);
+}
+
+/*
+ * SCMI vendor specific protocol
+ */
+#define SCMI_SYS_VENDOR_EXT_PROTO_ID		0x80
+
+#endif /* SCMI_PRIVATE_H */
diff --git a/drivers/arm/css/scmi/scmi_pwr_dmn_proto.c b/drivers/arm/css/scmi/scmi_pwr_dmn_proto.c
new file mode 100644
index 0000000..a342aa8
--- /dev/null
+++ b/drivers/arm/css/scmi/scmi_pwr_dmn_proto.c
@@ -0,0 +1,88 @@
+/*
+ * Copyright (c) 2017-2019, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <assert.h>
+
+#include <arch_helpers.h>
+#include <common/debug.h>
+#include <drivers/arm/css/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;
+	unsigned int token = 0;
+	int 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;
+	unsigned int token = 0;
+	int 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;
+}
diff --git a/drivers/arm/css/scmi/scmi_sys_pwr_proto.c b/drivers/arm/css/scmi/scmi_sys_pwr_proto.c
new file mode 100644
index 0000000..c8e62d1
--- /dev/null
+++ b/drivers/arm/css/scmi/scmi_sys_pwr_proto.c
@@ -0,0 +1,78 @@
+/*
+ * Copyright (c) 2017-2019, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <assert.h>
+
+#include <arch_helpers.h>
+#include <common/debug.h>
+#include <drivers/arm/css/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;
+	unsigned int token = 0;
+	int 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;
+	unsigned int token = 0;
+	int 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;
+}
diff --git a/drivers/arm/css/scmi/vendor/scmi_sq.c b/drivers/arm/css/scmi/vendor/scmi_sq.c
new file mode 100644
index 0000000..1037633
--- /dev/null
+++ b/drivers/arm/css/scmi/vendor/scmi_sq.c
@@ -0,0 +1,62 @@
+/*
+ * Copyright (c) 2019, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <assert.h>
+
+#include <arch_helpers.h>
+#include <common/debug.h>
+#include <drivers/arm/css/scmi.h>
+
+#include "scmi_private.h"
+#include "scmi_sq.h"
+
+#include <sq_common.h>
+
+/* SCMI message ID to get the available DRAM region */
+#define SCMI_VENDOR_EXT_MEMINFO_GET_MSG		0x3
+
+#define SCMI_VENDOR_EXT_MEMINFO_GET_MSG_LEN	4
+
+/*
+ * API to get the available DRAM region
+ */
+int scmi_get_draminfo(void *p, struct draminfo *info)
+{
+	mailbox_mem_t *mbx_mem;
+	int token = 0, ret;
+	scmi_channel_t *ch = (scmi_channel_t *)p;
+	struct dram_info_resp response;
+
+	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_VENDOR_EXT_PROTO_ID,
+			SCMI_VENDOR_EXT_MEMINFO_GET_MSG, token);
+	mbx_mem->len = SCMI_VENDOR_EXT_MEMINFO_GET_MSG_LEN;
+	mbx_mem->flags = SCMI_FLAG_RESP_POLL;
+
+	scmi_send_sync_command(ch);
+
+	/*
+	 * Ensure that any read to the SCPI payload area is done after reading
+	 * the MHU register. If these 2 reads were reordered then the CPU would
+	 * read invalid payload data
+	 */
+	dmbld();
+
+	/* Get the return values */
+	SCMI_PAYLOAD_RET_VAL1(mbx_mem->payload, ret);
+
+	memcpy(&response, (void *)mbx_mem->payload, sizeof(response));
+
+	scmi_put_channel(ch);
+
+	*info = response.info;
+
+	return ret;
+}
diff --git a/drivers/arm/css/scmi/vendor/scmi_sq.h b/drivers/arm/css/scmi/vendor/scmi_sq.h
new file mode 100644
index 0000000..aee1a3a
--- /dev/null
+++ b/drivers/arm/css/scmi/vendor/scmi_sq.h
@@ -0,0 +1,25 @@
+/*
+ * Copyright (c) 2019, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#ifndef SCMI_SQ_H
+#define SCMI_SQ_H
+
+#include <stddef.h>
+#include <stdint.h>
+
+#include <sq_common.h>
+
+/* Structure to represent available DRAM region */
+struct dram_info_resp {
+	int status;
+	int reserved;
+	struct draminfo info;
+};
+
+/* API to get the available DRAM region */
+int scmi_get_draminfo(void *p, struct draminfo *info);
+
+#endif /* SCMI_SQ_H */
diff --git a/drivers/arm/css/scp/css_bom_bootloader.c b/drivers/arm/css/scp/css_bom_bootloader.c
new file mode 100644
index 0000000..74121b4
--- /dev/null
+++ b/drivers/arm/css/scp/css_bom_bootloader.c
@@ -0,0 +1,195 @@
+/*
+ * Copyright (c) 2014-2020, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <assert.h>
+#include <stdint.h>
+
+#include <arch_helpers.h>
+#include <common/debug.h>
+#include <drivers/arm/css/css_mhu.h>
+#include <drivers/arm/css/css_scp.h>
+#include <drivers/arm/css/css_scpi.h>
+#include <plat/common/platform.h>
+#include <platform_def.h>
+
+/* ID of the MHU slot used for the BOM protocol */
+#define BOM_MHU_SLOT_ID		0
+
+/* Boot commands sent from AP -> SCP */
+#define BOOT_CMD_INFO	0x00
+#define BOOT_CMD_DATA	0x01
+
+/* BOM command header */
+typedef struct {
+	uint32_t id : 8;
+	uint32_t reserved : 24;
+} bom_cmd_t;
+
+typedef struct {
+	uint32_t image_size;
+	uint32_t checksum;
+} cmd_info_payload_t;
+
+/*
+ * Unlike the SCPI protocol, the boot protocol uses the same memory region
+ * for both AP -> SCP and SCP -> AP transfers; define the address of this...
+ */
+#define BOM_SHARED_MEM		PLAT_CSS_SCP_COM_SHARED_MEM_BASE
+#define BOM_CMD_HEADER		((bom_cmd_t *) BOM_SHARED_MEM)
+#define BOM_CMD_PAYLOAD		((void *) (BOM_SHARED_MEM + sizeof(bom_cmd_t)))
+
+typedef struct {
+	/* Offset from the base address of the Trusted RAM */
+	uint32_t offset;
+	uint32_t block_size;
+} cmd_data_payload_t;
+
+/*
+ * All CSS platforms load SCP_BL2/SCP_BL2U just below BL2 (this is where BL31
+ * usually resides except when ARM_BL31_IN_DRAM is
+ * set). Ensure that SCP_BL2/SCP_BL2U do not overflow into shared RAM and
+ * the fw_config.
+ */
+CASSERT(SCP_BL2_LIMIT <= BL2_BASE, assert_scp_bl2_overwrite_bl2);
+CASSERT(SCP_BL2U_LIMIT <= BL2_BASE, assert_scp_bl2u_overwrite_bl2);
+
+CASSERT(SCP_BL2_BASE >= ARM_FW_CONFIG_LIMIT, assert_scp_bl2_overflow);
+CASSERT(SCP_BL2U_BASE >= ARM_FW_CONFIG_LIMIT, assert_scp_bl2u_overflow);
+
+static void scp_boot_message_start(void)
+{
+	mhu_secure_message_start(BOM_MHU_SLOT_ID);
+}
+
+static void scp_boot_message_send(size_t payload_size)
+{
+	/* Ensure that any write to the BOM payload area is seen by SCP before
+	 * we write to the MHU register. If these 2 writes were reordered by
+	 * the CPU then SCP would read stale payload data */
+	dmbst();
+
+	/* Send command to SCP */
+	mhu_secure_message_send(BOM_MHU_SLOT_ID);
+}
+
+static uint32_t scp_boot_message_wait(size_t size)
+{
+	uint32_t mhu_status;
+
+	mhu_status = mhu_secure_message_wait();
+
+	/* Expect an SCP Boot Protocol message, reject any other protocol */
+	if (mhu_status != (1 << BOM_MHU_SLOT_ID)) {
+		ERROR("MHU: Unexpected protocol (MHU status: 0x%x)\n",
+			mhu_status);
+		panic();
+	}
+
+	/* Ensure that any read to the BOM payload area is done after reading
+	 * the MHU register. If these 2 reads were reordered then the CPU would
+	 * read invalid payload data */
+	dmbld();
+
+	return *(uint32_t *) BOM_SHARED_MEM;
+}
+
+static void scp_boot_message_end(void)
+{
+	mhu_secure_message_end(BOM_MHU_SLOT_ID);
+}
+
+int css_scp_boot_image_xfer(void *image, unsigned int image_size)
+{
+	uint32_t response;
+	uint32_t checksum;
+	cmd_info_payload_t *cmd_info_payload;
+	cmd_data_payload_t *cmd_data_payload;
+
+	assert((uintptr_t) image == SCP_BL2_BASE);
+
+	if ((image_size == 0) || (image_size % 4 != 0)) {
+		ERROR("Invalid size for the SCP_BL2 image. Must be a multiple of "
+			"4 bytes and not zero (current size = 0x%x)\n",
+			image_size);
+		return -1;
+	}
+
+	/* Extract the checksum from the image */
+	checksum = *(uint32_t *) image;
+	image = (char *) image + sizeof(checksum);
+	image_size -= sizeof(checksum);
+
+	mhu_secure_init();
+
+	VERBOSE("Send info about the SCP_BL2 image to be transferred to SCP\n");
+
+	/*
+	 * Send information about the SCP firmware image about to be transferred
+	 * to SCP
+	 */
+	scp_boot_message_start();
+
+	BOM_CMD_HEADER->id = BOOT_CMD_INFO;
+	cmd_info_payload = BOM_CMD_PAYLOAD;
+	cmd_info_payload->image_size = image_size;
+	cmd_info_payload->checksum = checksum;
+
+	scp_boot_message_send(sizeof(*cmd_info_payload));
+#if CSS_DETECT_PRE_1_7_0_SCP
+	{
+		const uint32_t deprecated_scp_nack_cmd = 0x404;
+		uint32_t mhu_status;
+
+		VERBOSE("Detecting SCP version incompatibility\n");
+
+		mhu_status = mhu_secure_message_wait();
+		if (mhu_status == deprecated_scp_nack_cmd) {
+			ERROR("Detected an incompatible version of the SCP firmware.\n");
+			ERROR("Only versions from v1.7.0 onwards are supported.\n");
+			ERROR("Please update the SCP firmware.\n");
+			return -1;
+		}
+
+		VERBOSE("SCP version looks OK\n");
+	}
+#endif /* CSS_DETECT_PRE_1_7_0_SCP */
+	response = scp_boot_message_wait(sizeof(response));
+	scp_boot_message_end();
+
+	if (response != 0) {
+		ERROR("SCP BOOT_CMD_INFO returned error %u\n", response);
+		return -1;
+	}
+
+	VERBOSE("Transferring SCP_BL2 image to SCP\n");
+
+	/* Transfer SCP_BL2 image to SCP */
+	scp_boot_message_start();
+
+	BOM_CMD_HEADER->id = BOOT_CMD_DATA;
+	cmd_data_payload = BOM_CMD_PAYLOAD;
+	cmd_data_payload->offset = (uintptr_t) image - ARM_TRUSTED_SRAM_BASE;
+	cmd_data_payload->block_size = image_size;
+
+	scp_boot_message_send(sizeof(*cmd_data_payload));
+	response = scp_boot_message_wait(sizeof(response));
+	scp_boot_message_end();
+
+	if (response != 0) {
+		ERROR("SCP BOOT_CMD_DATA returned error %u\n", response);
+		return -1;
+	}
+
+	return 0;
+}
+
+int css_scp_boot_ready(void)
+{
+	VERBOSE("Waiting for SCP to signal it is ready to go on\n");
+
+	/* Wait for SCP to signal it's ready */
+	return scpi_wait_ready();
+}
diff --git a/drivers/arm/css/scp/css_pm_scmi.c b/drivers/arm/css/scp/css_pm_scmi.c
new file mode 100644
index 0000000..9fe8b37
--- /dev/null
+++ b/drivers/arm/css/scp/css_pm_scmi.c
@@ -0,0 +1,499 @@
+/*
+ * Copyright (c) 2017-2022, Arm Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <assert.h>
+#include <string.h>
+
+#include <arch_helpers.h>
+#include <common/debug.h>
+#include <drivers/arm/css/css_scp.h>
+#include <drivers/arm/css/scmi.h>
+#include <lib/mmio.h>
+#include <plat/arm/common/plat_arm.h>
+#include <plat/arm/css/common/css_pm.h>
+#include <plat/common/platform.h>
+#include <platform_def.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(_power_state, _max_level)		\
+		(_power_state) |= ((_max_level) & SCMI_PWR_STATE_MAX_PWR_LVL_MASK)\
+				<< SCMI_PWR_STATE_MAX_PWR_LVL_SHIFT
+#define SCMI_GET_PWR_STATE_MAX_PWR_LVL(_power_state)		\
+		(((_power_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(_power_state, _level, _level_state)		\
+		(_power_state) |= ((_level_state) & SCMI_PWR_STATE_LVL_MASK)	\
+				<< (SCMI_PWR_STATE_LVL_WIDTH * (_level))
+#define SCMI_GET_PWR_STATE_LVL(_power_state, _level)		\
+		(((_power_state) >> (SCMI_PWR_STATE_LVL_WIDTH * (_level))) &	\
+				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;
+
+/*
+ * The global handles for invoking the SCMI driver APIs after the driver
+ * has been initialized.
+ */
+static void *scmi_handles[PLAT_ARM_SCMI_CHANNEL_COUNT];
+
+/* The global SCMI channels array */
+static scmi_channel_t scmi_channels[PLAT_ARM_SCMI_CHANNEL_COUNT];
+
+/*
+ * Channel ID for the default SCMI channel.
+ * The default channel is used to issue SYSTEM level SCMI requests and is
+ * initialized to the channel which has the boot cpu as its resource.
+ */
+static uint32_t default_scmi_channel_id;
+
+/*
+ * TODO: Allow use of channel specific lock instead of using a single lock for
+ * all the channels.
+ */
+ARM_SCMI_INSTANTIATE_LOCK;
+
+/*
+ * Function to obtain the SCMI Domain ID and SCMI Channel number from the linear
+ * core position. The SCMI Channel number is encoded in the upper 16 bits and
+ * the Domain ID is encoded in the lower 16 bits in each entry of the mapping
+ * array exported by the platform.
+ */
+static void css_scp_core_pos_to_scmi_channel(unsigned int core_pos,
+		unsigned int *scmi_domain_id, unsigned int *scmi_channel_id)
+{
+	unsigned int composite_id;
+
+	composite_id = plat_css_core_pos_to_scmi_dmn_id_map[core_pos];
+
+	*scmi_channel_id = GET_SCMI_CHANNEL_ID(composite_id);
+	*scmi_domain_id = GET_SCMI_DOMAIN_ID(composite_id);
+}
+
+/*
+ * Helper function to suspend a CPU power domain and its parent power domains
+ * if applicable.
+ */
+void css_scp_suspend(const struct psci_power_state *target_state)
+{
+	int ret;
+
+	/* 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 on all SCMI channels */
+		ret = scmi_sys_pwr_state_set(
+				scmi_handles[default_scmi_channel_id],
+				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 !HW_ASSISTED_COHERENCY
+	unsigned int lvl, channel_id, domain_id;
+	uint32_t scmi_pwr_state = 0;
+	/*
+	 * If we reach here, then assert that power down at system power domain
+	 * level is running.
+	 */
+	assert(css_system_pwr_state(target_state) == 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);
+
+	css_scp_core_pos_to_scmi_channel(plat_my_core_pos(),
+			&domain_id, &channel_id);
+	ret = scmi_pwr_state_set(scmi_handles[channel_id],
+		domain_id, scmi_pwr_state);
+
+	if (ret != SCMI_E_SUCCESS) {
+		ERROR("SCMI set power state command return 0x%x unexpected\n",
+				ret);
+		panic();
+	}
+#endif
+}
+
+/*
+ * Helper function to turn off a CPU power domain and its parent power domains
+ * if applicable.
+ */
+void css_scp_off(const struct psci_power_state *target_state)
+{
+	unsigned int lvl = 0, channel_id, domain_id;
+	int 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(css_system_pwr_state(target_state) == 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);
+
+	css_scp_core_pos_to_scmi_channel(plat_my_core_pos(),
+			&domain_id, &channel_id);
+	ret = scmi_pwr_state_set(scmi_handles[channel_id],
+		domain_id, 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)
+{
+	unsigned int lvl = 0, channel_id, core_pos, domain_id;
+	int 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);
+
+	core_pos = (unsigned int)plat_core_pos_by_mpidr(mpidr);
+	assert(core_pos < PLATFORM_CORE_COUNT);
+
+	css_scp_core_pos_to_scmi_channel(core_pos, &domain_id,
+			&channel_id);
+	ret = scmi_pwr_state_set(scmi_handles[channel_id],
+		domain_id, 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;
+	uint32_t scmi_pwr_state = 0, lvl_state;
+	unsigned int channel_id, cpu_idx, domain_id;
+
+	/* 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 = (unsigned int)plat_core_pos_by_mpidr(mpidr);
+	assert(cpu_idx < PLATFORM_CORE_COUNT);
+
+	css_scp_core_pos_to_scmi_channel(cpu_idx, &domain_id, &channel_id);
+	ret = scmi_pwr_state_get(scmi_handles[channel_id],
+		domain_id, &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;
+}
+
+/*
+ * Callback function to raise a SGI designated to trigger the CPU power down
+ * sequence on all the online secondary cores.
+ */
+static void css_raise_pwr_down_interrupt(u_register_t mpidr)
+{
+#if CSS_SYSTEM_GRACEFUL_RESET
+	plat_ic_raise_el3_sgi(CSS_CPU_PWR_DOWN_REQ_INTR, mpidr);
+#endif
+}
+
+void __dead2 css_scp_system_off(int state)
+{
+	int ret;
+
+	/*
+	 * Before issuing the system power down command, set the trusted mailbox
+	 * to 0. This will ensure that in the case of a warm/cold reset, the
+	 * primary CPU executes from the cold boot sequence.
+	 */
+	mmio_write_64(PLAT_ARM_TRUSTED_MAILBOX_BASE, 0U);
+
+	/*
+	 * Send powerdown request to online secondary core(s)
+	 */
+	ret = psci_stop_other_cores(0, css_raise_pwr_down_interrupt);
+	if (ret != PSCI_E_SUCCESS) {
+		ERROR("Failed to powerdown secondary core(s)\n");
+	}
+
+	/*
+	 * Disable GIC CPU interface to prevent pending interrupt from waking
+	 * up the AP from WFI.
+	 */
+	plat_arm_gic_cpuif_disable();
+	plat_arm_gic_redistif_off();
+
+	/*
+	 * Issue SCMI command. First issue a graceful
+	 * request and if that fails force the request.
+	 */
+	ret = scmi_sys_pwr_state_set(scmi_handles[default_scmi_channel_id],
+			SCMI_SYS_PWR_FORCEFUL_REQ,
+			state);
+
+	if (ret != SCMI_E_SUCCESS) {
+		ERROR("SCMI system power state set 0x%x returns unexpected 0x%x\n",
+			state, ret);
+		panic();
+	}
+
+	/* Powerdown of primary core */
+	psci_pwrdown_cpu(PLAT_MAX_PWR_LVL);
+	wfi();
+	ERROR("CSS set power state: operation not handled.\n");
+	panic();
+}
+
+/*
+ * Helper function to shutdown the system via SCMI.
+ */
+void __dead2 css_scp_sys_shutdown(void)
+{
+	css_scp_system_off(SCMI_SYS_PWR_SHUTDOWN);
+}
+
+/*
+ * Helper function to reset the system via SCMI.
+ */
+void __dead2 css_scp_sys_reboot(void)
+{
+	css_scp_system_off(SCMI_SYS_PWR_COLD_RESET);
+}
+
+static int scmi_ap_core_init(scmi_channel_t *ch)
+{
+#if PROGRAMMABLE_RESET_ADDRESS
+	uint32_t version;
+	int ret;
+
+	ret = scmi_proto_version(ch, SCMI_AP_CORE_PROTO_ID, &version);
+	if (ret != SCMI_E_SUCCESS) {
+		WARN("SCMI AP core protocol version message failed\n");
+		return -1;
+	}
+
+	if (!is_scmi_version_compatible(SCMI_AP_CORE_PROTO_VER, version)) {
+		WARN("SCMI AP core protocol version 0x%x incompatible with driver version 0x%x\n",
+			version, SCMI_AP_CORE_PROTO_VER);
+		return -1;
+	}
+	INFO("SCMI AP core protocol version 0x%x detected\n", version);
+#endif
+	return 0;
+}
+
+void __init plat_arm_pwrc_setup(void)
+{
+	unsigned int composite_id, idx;
+
+	for (idx = 0; idx < PLAT_ARM_SCMI_CHANNEL_COUNT; idx++) {
+		INFO("Initializing SCMI driver on channel %d\n", idx);
+
+		scmi_channels[idx].info = plat_css_get_scmi_info(idx);
+		scmi_channels[idx].lock = ARM_SCMI_LOCK_GET_INSTANCE;
+		scmi_handles[idx] = scmi_init(&scmi_channels[idx]);
+
+		if (scmi_handles[idx] == NULL) {
+			ERROR("SCMI Initialization failed on channel %d\n", idx);
+			panic();
+		}
+
+		if (scmi_ap_core_init(&scmi_channels[idx]) < 0) {
+			ERROR("SCMI AP core protocol initialization failed\n");
+			panic();
+		}
+	}
+
+	composite_id = plat_css_core_pos_to_scmi_dmn_id_map[plat_my_core_pos()];
+	default_scmi_channel_id = GET_SCMI_CHANNEL_ID(composite_id);
+}
+
+/******************************************************************************
+ * 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 *css_scmi_override_pm_ops(plat_psci_ops_t *ops)
+{
+	uint32_t msg_attr;
+	int ret;
+	void *scmi_handle = scmi_handles[default_scmi_channel_id];
+
+	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;
+		}
+		if (!(msg_attr & SCMI_SYS_PWR_WARM_RESET_SUPPORTED)) {
+			/*
+			 * WARM reset is not available.
+			 */
+			ops->system_reset2 = NULL;
+		}
+	}
+
+	return ops;
+}
+
+int css_system_reset2(int is_vendor, int reset_type, u_register_t cookie)
+{
+	if (is_vendor || (reset_type != PSCI_RESET2_SYSTEM_WARM_RESET))
+		return PSCI_E_INVALID_PARAMS;
+
+	css_scp_system_off(SCMI_SYS_PWR_WARM_RESET);
+	/*
+	 * css_scp_system_off cannot return (it is a __dead function),
+	 * but css_system_reset2 has to return some value, even in
+	 * this case.
+	 */
+	return 0;
+}
+
+#if PROGRAMMABLE_RESET_ADDRESS
+void plat_arm_program_trusted_mailbox(uintptr_t address)
+{
+	int ret, i;
+
+	for (i = 0; i < PLAT_ARM_SCMI_CHANNEL_COUNT; i++) {
+		assert(scmi_handles[i]);
+
+		ret = scmi_ap_core_set_reset_addr(scmi_handles[i], address,
+				SCMI_AP_CORE_LOCK_ATTR);
+		if (ret != SCMI_E_SUCCESS) {
+			ERROR("CSS: Failed to program reset address: %d\n", ret);
+			panic();
+		}
+	}
+}
+#endif
diff --git a/drivers/arm/css/scp/css_pm_scpi.c b/drivers/arm/css/scp/css_pm_scpi.c
new file mode 100644
index 0000000..b4019ce
--- /dev/null
+++ b/drivers/arm/css/scp/css_pm_scpi.c
@@ -0,0 +1,165 @@
+/*
+ * Copyright (c) 2016-2018, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <assert.h>
+
+#include <arch_helpers.h>
+#include <common/debug.h>
+#include <drivers/arm/css/css_scp.h>
+#include <drivers/arm/css/css_scpi.h>
+#include <plat/arm/common/plat_arm.h>
+#include <plat/arm/css/common/css_pm.h>
+
+/*
+ * This file implements the SCP power management functions using SCPI protocol.
+ */
+
+/*
+ * Helper function to inform power down state to SCP.
+ */
+void css_scp_suspend(const struct psci_power_state *target_state)
+{
+	uint32_t cluster_state = scpi_power_on;
+	uint32_t system_state = scpi_power_on;
+
+	/* Check if power down at system power domain level is requested */
+	if (css_system_pwr_state(target_state) == ARM_LOCAL_STATE_OFF)
+		system_state = scpi_power_retention;
+
+	/* Cluster is to be turned off, so disable coherency */
+	if (CSS_CLUSTER_PWR_STATE(target_state) == ARM_LOCAL_STATE_OFF)
+		cluster_state = scpi_power_off;
+
+	/*
+	 * Ask the SCP to power down the appropriate components depending upon
+	 * their state.
+	 */
+	scpi_set_css_power_state(read_mpidr_el1(),
+				 scpi_power_off,
+				 cluster_state,
+				 system_state);
+}
+
+/*
+ * Helper function to turn off a CPU power domain and its parent power domains
+ * if applicable. Since SCPI doesn't differentiate between OFF and suspend, we
+ * call the suspend helper here.
+ */
+void css_scp_off(const struct psci_power_state *target_state)
+{
+	css_scp_suspend(target_state);
+}
+
+/*
+ * Helper function to turn ON a CPU power domain and its parent power domains
+ * if applicable.
+ */
+void css_scp_on(u_register_t mpidr)
+{
+	/*
+	 * SCP takes care of powering up parent power domains so we
+	 * only need to care about level 0
+	 */
+	scpi_set_css_power_state(mpidr, scpi_power_on, scpi_power_on,
+				 scpi_power_on);
+}
+
+/*
+ * 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 rc, element;
+	unsigned int cpu_state, cluster_state;
+
+	/*
+	 * The format of 'power_level' is implementation-defined, but 0 must
+	 * mean a CPU. We also allow 1 to denote the cluster
+	 */
+	if (power_level != ARM_PWR_LVL0 && power_level != ARM_PWR_LVL1)
+		return PSCI_E_INVALID_PARAMS;
+
+	/* Query SCP */
+	rc = scpi_get_css_power_state(mpidr, &cpu_state, &cluster_state);
+	if (rc != 0)
+		return PSCI_E_INVALID_PARAMS;
+
+	/* Map power states of CPU and cluster to expected PSCI return codes */
+	if (power_level == ARM_PWR_LVL0) {
+		/*
+		 * The CPU state returned by SCP is an 8-bit bit mask
+		 * corresponding to each CPU in the cluster
+		 */
+#if ARM_PLAT_MT
+		/*
+		 * The current SCPI driver only caters for single-threaded
+		 * platforms. Hence we ignore the thread ID (which is always 0)
+		 * for such platforms.
+		 */
+		element = (mpidr >> MPIDR_AFF1_SHIFT) & MPIDR_AFFLVL_MASK;
+#else
+		element = mpidr & MPIDR_AFFLVL_MASK;
+#endif  /* ARM_PLAT_MT */
+		return CSS_CPU_PWR_STATE(cpu_state, element) ==
+			CSS_CPU_PWR_STATE_ON ? HW_ON : HW_OFF;
+	} else {
+		assert(cluster_state == CSS_CLUSTER_PWR_STATE_ON ||
+				cluster_state == CSS_CLUSTER_PWR_STATE_OFF);
+		return cluster_state == CSS_CLUSTER_PWR_STATE_ON ? HW_ON :
+			HW_OFF;
+	}
+}
+
+/*
+ * Helper function to shutdown the system via SCPI.
+ */
+void __dead2 css_scp_sys_shutdown(void)
+{
+	uint32_t response;
+
+	/*
+	 * Disable GIC CPU interface to prevent pending interrupt
+	 * from waking up the AP from WFI.
+	 */
+	plat_arm_gic_cpuif_disable();
+
+	/* Send the power down request to the SCP */
+	response = scpi_sys_power_state(scpi_system_shutdown);
+
+	if (response != SCP_OK) {
+		ERROR("CSS System Off: SCP error %u.\n", response);
+		panic();
+	}
+	wfi();
+	ERROR("CSS System Off: operation not handled.\n");
+	panic();
+}
+
+/*
+ * Helper function to reset the system via SCPI.
+ */
+void __dead2 css_scp_sys_reboot(void)
+{
+	uint32_t response;
+
+	/*
+	 * Disable GIC CPU interface to prevent pending interrupt
+	 * from waking up the AP from WFI.
+	 */
+	plat_arm_gic_cpuif_disable();
+
+	/* Send the system reset request to the SCP */
+	response = scpi_sys_power_state(scpi_system_reboot);
+
+	if (response != SCP_OK) {
+		ERROR("CSS System Reset: SCP error %u.\n", response);
+		panic();
+	}
+	wfi();
+	ERROR("CSS System Reset: operation not handled.\n");
+	panic();
+}
diff --git a/drivers/arm/css/scp/css_sds.c b/drivers/arm/css/scp/css_sds.c
new file mode 100644
index 0000000..e42ee10
--- /dev/null
+++ b/drivers/arm/css/scp/css_sds.c
@@ -0,0 +1,95 @@
+/*
+ * Copyright (c) 2014-2017, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <assert.h>
+#include <stdint.h>
+
+#include <arch_helpers.h>
+#include <common/debug.h>
+#include <drivers/arm/css/css_scp.h>
+#include <drivers/arm/css/sds.h>
+#include <drivers/delay_timer.h>
+#include <plat/common/platform.h>
+#include <platform_def.h>
+
+int css_scp_boot_image_xfer(void *image, unsigned int image_size)
+{
+	int ret;
+	unsigned int image_offset, image_flags;
+
+	ret = sds_init();
+	if (ret != SDS_OK) {
+		ERROR("SCP SDS initialization failed\n");
+		panic();
+	}
+
+	VERBOSE("Writing SCP image metadata\n");
+	image_offset = (uintptr_t) image - ARM_TRUSTED_SRAM_BASE;
+	ret = sds_struct_write(SDS_SCP_IMG_STRUCT_ID, SDS_SCP_IMG_ADDR_OFFSET,
+			&image_offset, SDS_SCP_IMG_ADDR_SIZE,
+			SDS_ACCESS_MODE_NON_CACHED);
+	if (ret != SDS_OK)
+		goto sds_fail;
+
+	ret = sds_struct_write(SDS_SCP_IMG_STRUCT_ID, SDS_SCP_IMG_SIZE_OFFSET,
+			&image_size, SDS_SCP_IMG_SIZE_SIZE,
+			SDS_ACCESS_MODE_NON_CACHED);
+	if (ret != SDS_OK)
+		goto sds_fail;
+
+	VERBOSE("Marking SCP image metadata as valid\n");
+	image_flags = SDS_SCP_IMG_VALID_FLAG_BIT;
+	ret = sds_struct_write(SDS_SCP_IMG_STRUCT_ID, SDS_SCP_IMG_FLAG_OFFSET,
+			&image_flags, SDS_SCP_IMG_FLAG_SIZE,
+			SDS_ACCESS_MODE_NON_CACHED);
+	if (ret != SDS_OK)
+		goto sds_fail;
+
+	return 0;
+sds_fail:
+	ERROR("SCP SDS write to SCP IMG struct failed\n");
+	panic();
+}
+
+/*
+ * API to wait for SCP to signal till it's ready after booting the transferred
+ * image.
+ */
+int css_scp_boot_ready(void)
+{
+	uint32_t scp_feature_availability_flags;
+	int ret, retry = CSS_SCP_READY_10US_RETRIES;
+
+
+	VERBOSE("Waiting for SCP RAM to complete its initialization process\n");
+
+	/* Wait for the SCP RAM Firmware to complete its initialization process */
+	while (retry > 0) {
+		ret = sds_struct_read(SDS_FEATURE_AVAIL_STRUCT_ID, 0,
+				&scp_feature_availability_flags,
+				SDS_FEATURE_AVAIL_SIZE,
+				SDS_ACCESS_MODE_NON_CACHED);
+		if (ret == SDS_ERR_STRUCT_NOT_FINALIZED)
+			continue;
+
+		if (ret != SDS_OK) {
+			ERROR(" sds_struct_read failed\n");
+			panic();
+		}
+
+		if (scp_feature_availability_flags &
+				SDS_FEATURE_AVAIL_SCP_RAM_READY_BIT)
+			return 0;
+
+		udelay(10);
+		retry--;
+	}
+
+	ERROR("Timeout of %d ms expired waiting for SCP RAM Ready flag\n",
+			CSS_SCP_READY_10US_RETRIES/100);
+
+	plat_panic_handler();
+}
diff --git a/drivers/arm/css/scpi/css_scpi.c b/drivers/arm/css/scpi/css_scpi.c
new file mode 100644
index 0000000..416356b
--- /dev/null
+++ b/drivers/arm/css/scpi/css_scpi.c
@@ -0,0 +1,272 @@
+/*
+ * Copyright (c) 2014-2020, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <assert.h>
+#include <string.h>
+
+#include <arch_helpers.h>
+#include <common/debug.h>
+#include <drivers/arm/css/css_mhu.h>
+#include <drivers/arm/css/css_scpi.h>
+#include <lib/utils.h>
+#include <plat/common/platform.h>
+#include <platform_def.h>
+
+#define SCPI_SHARED_MEM_SCP_TO_AP	PLAT_CSS_SCP_COM_SHARED_MEM_BASE
+#define SCPI_SHARED_MEM_AP_TO_SCP	(PLAT_CSS_SCP_COM_SHARED_MEM_BASE \
+								 + 0x100)
+
+/* Header and payload addresses for commands from AP to SCP */
+#define SCPI_CMD_HEADER_AP_TO_SCP		\
+	((scpi_cmd_t *) SCPI_SHARED_MEM_AP_TO_SCP)
+#define SCPI_CMD_PAYLOAD_AP_TO_SCP		\
+	((void *) (SCPI_SHARED_MEM_AP_TO_SCP + sizeof(scpi_cmd_t)))
+
+/* Header and payload addresses for responses from SCP to AP */
+#define SCPI_RES_HEADER_SCP_TO_AP \
+	((scpi_cmd_t *) SCPI_SHARED_MEM_SCP_TO_AP)
+#define SCPI_RES_PAYLOAD_SCP_TO_AP \
+	((void *) (SCPI_SHARED_MEM_SCP_TO_AP + sizeof(scpi_cmd_t)))
+
+/* ID of the MHU slot used for the SCPI protocol */
+#define SCPI_MHU_SLOT_ID		0
+
+static void scpi_secure_message_start(void)
+{
+	mhu_secure_message_start(SCPI_MHU_SLOT_ID);
+}
+
+static void scpi_secure_message_send(size_t payload_size)
+{
+	/*
+	 * Ensure that any write to the SCPI payload area is seen by SCP before
+	 * we write to the MHU register. If these 2 writes were reordered by
+	 * the CPU then SCP would read stale payload data
+	 */
+	dmbst();
+
+	mhu_secure_message_send(SCPI_MHU_SLOT_ID);
+}
+
+static int scpi_secure_message_receive(scpi_cmd_t *cmd)
+{
+	uint32_t mhu_status;
+
+	assert(cmd != NULL);
+
+	mhu_status = mhu_secure_message_wait();
+
+	/* Expect an SCPI message, reject any other protocol */
+	if (mhu_status != (1 << SCPI_MHU_SLOT_ID)) {
+		ERROR("MHU: Unexpected protocol (MHU status: 0x%x)\n",
+			mhu_status);
+		return -1;
+	}
+
+	/*
+	 * Ensure that any read to the SCPI payload area is done after reading
+	 * the MHU register. If these 2 reads were reordered then the CPU would
+	 * read invalid payload data
+	 */
+	dmbld();
+
+	memcpy(cmd, (void *) SCPI_SHARED_MEM_SCP_TO_AP, sizeof(*cmd));
+
+	return 0;
+}
+
+static void scpi_secure_message_end(void)
+{
+	mhu_secure_message_end(SCPI_MHU_SLOT_ID);
+}
+
+int scpi_wait_ready(void)
+{
+	scpi_cmd_t scpi_cmd;
+	int rc;
+
+	VERBOSE("Waiting for SCP_READY command...\n");
+
+	/* Get a message from the SCP */
+	scpi_secure_message_start();
+	rc = scpi_secure_message_receive(&scpi_cmd);
+	scpi_secure_message_end();
+
+	/* If no message was received, don't send a response */
+	if (rc != 0)
+		return rc;
+
+	/* We are expecting 'SCP Ready', produce correct error if it's not */
+	scpi_status_t status = SCP_OK;
+	if (scpi_cmd.id != SCPI_CMD_SCP_READY) {
+		ERROR("Unexpected SCP command: expected command #%u, got command #%u\n",
+		      SCPI_CMD_SCP_READY, scpi_cmd.id);
+		status = SCP_E_SUPPORT;
+	} else if (scpi_cmd.size != 0) {
+		ERROR("SCP_READY command has incorrect size: expected 0, got %u\n",
+		      scpi_cmd.size);
+		status = SCP_E_SIZE;
+	}
+
+	VERBOSE("Sending response for SCP_READY command\n");
+
+	/*
+	 * Send our response back to SCP.
+	 * We are using the same SCPI header, just update the status field.
+	 */
+	scpi_cmd.status = status;
+	scpi_secure_message_start();
+	memcpy((void *) SCPI_SHARED_MEM_AP_TO_SCP, &scpi_cmd, sizeof(scpi_cmd));
+	scpi_secure_message_send(0);
+	scpi_secure_message_end();
+
+	return status == SCP_OK ? 0 : -1;
+}
+
+void scpi_set_css_power_state(unsigned int mpidr,
+		scpi_power_state_t cpu_state, scpi_power_state_t cluster_state,
+		scpi_power_state_t css_state)
+{
+	scpi_cmd_t *cmd;
+	uint32_t state = 0;
+	uint32_t *payload_addr;
+
+#if ARM_PLAT_MT
+	/*
+	 * The current SCPI driver only caters for single-threaded platforms.
+	 * Hence we ignore the thread ID (which is always 0) for such platforms.
+	 */
+	state |= (mpidr >> MPIDR_AFF1_SHIFT) & 0x0f;	/* CPU ID */
+	state |= ((mpidr >> MPIDR_AFF2_SHIFT) & 0x0f) << 4;	/* Cluster ID */
+#else
+	state |= mpidr & 0x0f;	/* CPU ID */
+	state |= (mpidr & 0xf00) >> 4;	/* Cluster ID */
+#endif /* ARM_PLAT_MT */
+
+	state |= cpu_state << 8;
+	state |= cluster_state << 12;
+	state |= css_state << 16;
+
+	scpi_secure_message_start();
+
+	/* Populate the command header */
+	cmd = SCPI_CMD_HEADER_AP_TO_SCP;
+	cmd->id = SCPI_CMD_SET_CSS_POWER_STATE;
+	cmd->set = SCPI_SET_NORMAL;
+	cmd->sender = 0;
+	cmd->size = sizeof(state);
+	/* Populate the command payload */
+	payload_addr = SCPI_CMD_PAYLOAD_AP_TO_SCP;
+	*payload_addr = state;
+	scpi_secure_message_send(sizeof(state));
+	/*
+	 * SCP does not reply to this command in order to avoid MHU interrupts
+	 * from the sender, which could interfere with its power state request.
+	 */
+
+	scpi_secure_message_end();
+}
+
+/*
+ * Query and obtain CSS power state from SCP.
+ *
+ * In response to the query, SCP returns power states of all CPUs in all
+ * clusters of the system. The returned response is then filtered based on the
+ * supplied MPIDR. Power states of requested cluster and CPUs within are updated
+ * via supplied non-NULL pointer arguments.
+ *
+ * Returns 0 on success, or -1 on errors.
+ */
+int scpi_get_css_power_state(unsigned int mpidr, unsigned int *cpu_state_p,
+		unsigned int *cluster_state_p)
+{
+	scpi_cmd_t *cmd;
+	scpi_cmd_t response;
+	int power_state, cpu, cluster, rc = -1;
+
+	/*
+	 * Extract CPU and cluster membership of the given MPIDR. SCPI caters
+	 * for only up to 0xf clusters, and 8 CPUs per cluster
+	 */
+#if ARM_PLAT_MT
+	/*
+	 * The current SCPI driver only caters for single-threaded platforms.
+	 * Hence we ignore the thread ID (which is always 0) for such platforms.
+	 */
+	cpu = (mpidr >> MPIDR_AFF1_SHIFT) & MPIDR_AFFLVL_MASK;
+	cluster = (mpidr >> MPIDR_AFF2_SHIFT) & MPIDR_AFFLVL_MASK;
+#else
+	cpu = mpidr & MPIDR_AFFLVL_MASK;
+	cluster = (mpidr >> MPIDR_AFF1_SHIFT) & MPIDR_AFFLVL_MASK;
+#endif  /* ARM_PLAT_MT */
+	if (cpu >= 8 || cluster >= 0xf)
+		return -1;
+
+	scpi_secure_message_start();
+
+	/* Populate request headers */
+	zeromem(SCPI_CMD_HEADER_AP_TO_SCP, sizeof(*cmd));
+	cmd = SCPI_CMD_HEADER_AP_TO_SCP;
+	cmd->id = SCPI_CMD_GET_CSS_POWER_STATE;
+
+	/*
+	 * Send message and wait for SCP's response
+	 */
+	scpi_secure_message_send(0);
+	if (scpi_secure_message_receive(&response) != 0)
+		goto exit;
+
+	if (response.status != SCP_OK)
+		goto exit;
+
+	/* Validate SCP response */
+	if (!CHECK_RESPONSE(response, cluster))
+		goto exit;
+
+	/* Extract power states for required cluster */
+	power_state = *(((uint16_t *) SCPI_RES_PAYLOAD_SCP_TO_AP) + cluster);
+	if (CLUSTER_ID(power_state) != cluster)
+		goto exit;
+
+	/* Update power state via pointers */
+	if (cluster_state_p)
+		*cluster_state_p = CLUSTER_POWER_STATE(power_state);
+	if (cpu_state_p)
+		*cpu_state_p = CPU_POWER_STATE(power_state);
+	rc = 0;
+
+exit:
+	scpi_secure_message_end();
+	return rc;
+}
+
+uint32_t scpi_sys_power_state(scpi_system_state_t system_state)
+{
+	scpi_cmd_t *cmd;
+	uint8_t *payload_addr;
+	scpi_cmd_t response;
+
+	scpi_secure_message_start();
+
+	/* Populate the command header */
+	cmd = SCPI_CMD_HEADER_AP_TO_SCP;
+	cmd->id = SCPI_CMD_SYS_POWER_STATE;
+	cmd->set = 0;
+	cmd->sender = 0;
+	cmd->size = sizeof(*payload_addr);
+	/* Populate the command payload */
+	payload_addr = SCPI_CMD_PAYLOAD_AP_TO_SCP;
+	*payload_addr = system_state & 0xff;
+	scpi_secure_message_send(sizeof(*payload_addr));
+
+	/* If no response is received, fill in an error status */
+	if (scpi_secure_message_receive(&response) != 0)
+		response.status = SCP_E_TIMEOUT;
+
+	scpi_secure_message_end();
+
+	return response.status;
+}
diff --git a/drivers/arm/css/sds/aarch32/sds_helpers.S b/drivers/arm/css/sds/aarch32/sds_helpers.S
new file mode 100644
index 0000000..13ff0e1
--- /dev/null
+++ b/drivers/arm/css/sds/aarch32/sds_helpers.S
@@ -0,0 +1,64 @@
+/*
+ * Copyright (c) 2017, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <arch.h>
+#include <asm_macros.S>
+#include <drivers/arm/css/sds.h>
+#include <platform_def.h>
+
+#include "../sds_private.h"
+
+	.globl	sds_get_primary_cpu_id
+
+	/*
+	 * int sds_get_primary_cpu_id(void);
+	 * Return the primary CPU ID from SDS Structure
+	 * Returns CPUID on success or -1 on failure
+	 */
+func sds_get_primary_cpu_id
+	ldr	r0, =PLAT_ARM_SDS_MEM_BASE
+	ldr	r2, =SDS_REGION_SIGNATURE
+	ldr	r1, [r0]
+	ubfx	r3, r1, #0, #16
+
+	/* Check if the SDS region signature found */
+	cmp	r2, r3
+	bne	2f
+
+	/* Get the structure count from region descriptor in r1 */
+	ubfx	r1, r1, #SDS_REGION_STRUCT_COUNT_SHIFT, #SDS_REGION_STRUCT_COUNT_WIDTH
+	cmp	r1, #0
+	beq	2f
+	add	r0, r0, #SDS_REGION_DESC_SIZE
+
+	/* Initialize the loop iterator count in r3 */
+	mov	r3, #0
+loop_begin:
+	ldrh	r2, [r0]
+	cmp	r2, #SDS_AP_CPU_INFO_STRUCT_ID
+	bne	continue_loop
+
+	/* We have found the required structure */
+	ldr	r0, [r0,#(SDS_HEADER_SIZE + SDS_AP_CPU_INFO_PRIMARY_CPUID_OFFSET)]
+	bx	lr
+continue_loop:
+	/* Increment the loop counter and exit loop if counter == structure count */
+	add	r3, r3, #0x1
+	cmp	r1, r3
+	beq	2f
+
+	/* Read the 2nd word in header */
+	ldr	r2, [r0,#4]
+	/* Get the structure size from header */
+	ubfx	r2, r2, #SDS_HEADER_STRUCT_SIZE_SHIFT, #SDS_HEADER_STRUCT_SIZE_WIDTH
+	/* Add the structure size and SDS HEADER SIZE to point to next header */
+	add	r2, r2, #SDS_HEADER_SIZE
+	add	r0, r0, r2
+	b	loop_begin
+2:
+	mov	r0, #0xffffffff
+	bx	lr
+endfunc sds_get_primary_cpu_id
diff --git a/drivers/arm/css/sds/aarch64/sds_helpers.S b/drivers/arm/css/sds/aarch64/sds_helpers.S
new file mode 100644
index 0000000..3256c2b
--- /dev/null
+++ b/drivers/arm/css/sds/aarch64/sds_helpers.S
@@ -0,0 +1,62 @@
+/*
+ * Copyright (c) 2017, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <arch.h>
+#include <asm_macros.S>
+#include <drivers/arm/css/sds.h>
+#include <platform_def.h>
+
+#include "../sds_private.h"
+
+	.globl	sds_get_primary_cpu_id
+
+	/*
+	 * int sds_get_primary_cpu_id(void);
+	 * Return the primary CPI ID from SDS Structure
+	 * Returns CPUID on success or -1 on failure
+	 */
+func sds_get_primary_cpu_id
+	mov_imm	x0, PLAT_ARM_SDS_MEM_BASE
+	mov	w2, #SDS_REGION_SIGNATURE
+	ldr	w1, [x0]
+
+	/* Check if the SDS region signature found */
+	cmp	w2, w1, uxth
+	b.ne	2f
+
+	/* Get the structure count from region descriptor in `w1 */
+	ubfx	w1, w1, #SDS_REGION_STRUCT_COUNT_SHIFT, #SDS_REGION_STRUCT_COUNT_WIDTH
+	cbz	w1, 2f
+	add	x0, x0, #SDS_REGION_DESC_SIZE
+
+	/* Initialize the loop iterator count in w3 */
+	mov	w3, #0
+loop_begin:
+	ldrh	w2, [x0]
+	cmp	w2, #SDS_AP_CPU_INFO_STRUCT_ID
+	b.ne	continue_loop
+
+	/* We have found the required structure */
+	ldr	w0, [x0,#(SDS_HEADER_SIZE + SDS_AP_CPU_INFO_PRIMARY_CPUID_OFFSET)]
+	ret
+continue_loop:
+	/* Increment the loop counter and exit loop if counter == structure count */
+	add	w3, w3, #0x1
+	cmp	w1, w3
+	b.eq	2f
+
+	/* Read the 2nd word in header */
+	ldr	w2, [x0,#4]
+	/* Get the structure size from header */
+	ubfx	x2, x2, #SDS_HEADER_STRUCT_SIZE_SHIFT, #SDS_HEADER_STRUCT_SIZE_WIDTH
+	/* Add the structure size and SDS HEADER SIZE to point to next header */
+	add	x2, x2, #SDS_HEADER_SIZE
+	add	x0, x0, x2
+	b	loop_begin
+2:
+	mov	w0, #0xffffffff
+	ret
+endfunc sds_get_primary_cpu_id
diff --git a/drivers/arm/css/sds/sds.c b/drivers/arm/css/sds/sds.c
new file mode 100644
index 0000000..1fb196c
--- /dev/null
+++ b/drivers/arm/css/sds/sds.c
@@ -0,0 +1,259 @@
+/*
+ * Copyright (c) 2017, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <assert.h>
+#include <stdint.h>
+#include <string.h>
+
+#include <arch_helpers.h>
+#include <common/debug.h>
+#include <drivers/arm/css/sds.h>
+#include <platform_def.h>
+
+#include "sds_private.h"
+
+/*
+ * Variables used to track and maintain the state of the memory region reserved
+ * for usage by the SDS framework.
+ */
+
+/* Pointer to the base of the SDS memory region */
+static uintptr_t sds_mem_base;
+
+/* Size of the SDS memory region in bytes */
+static size_t sds_mem_size;
+
+/*
+ * Perform some non-exhaustive tests to determine whether any of the fields
+ * within a Structure Header contain obviously invalid data.
+ * Returns SDS_OK on success, SDS_ERR_FAIL on error.
+ */
+static int sds_struct_is_valid(uintptr_t header)
+{
+	size_t struct_size = GET_SDS_HEADER_STRUCT_SIZE(header);
+
+	/* Zero is not a valid identifier */
+	if (GET_SDS_HEADER_ID(header) == 0)
+		return SDS_ERR_FAIL;
+
+	/* Check SDS Schema version */
+	if (GET_SDS_HEADER_VERSION(header) == SDS_REGION_SCH_VERSION)
+		return SDS_ERR_FAIL;
+
+	/* The SDS Structure sizes have to be multiple of 8 */
+	if ((struct_size == 0) || ((struct_size % 8) != 0))
+		return SDS_ERR_FAIL;
+
+	if (struct_size > sds_mem_size)
+		return SDS_ERR_FAIL;
+
+	return SDS_OK;
+}
+
+/*
+ * Validate the SDS structure headers.
+ * Returns SDS_OK on success, SDS_ERR_FAIL on error.
+ */
+static int validate_sds_struct_headers(void)
+{
+	unsigned int i, structure_count;
+	uintptr_t header;
+
+	structure_count = GET_SDS_REGION_STRUCTURE_COUNT(sds_mem_base);
+
+	if (structure_count == 0)
+		return SDS_ERR_FAIL;
+
+	header = sds_mem_base + SDS_REGION_DESC_SIZE;
+
+	/* Iterate over structure headers and validate each one */
+	for (i = 0; i < structure_count; i++) {
+		if (sds_struct_is_valid(header) != SDS_OK) {
+			WARN("SDS: Invalid structure header detected\n");
+			return SDS_ERR_FAIL;
+		}
+		header += GET_SDS_HEADER_STRUCT_SIZE(header) + SDS_HEADER_SIZE;
+	}
+	return SDS_OK;
+}
+
+/*
+ * Get the structure header pointer corresponding to the structure ID.
+ * Returns SDS_OK on success, SDS_ERR_STRUCT_NOT_FOUND on error.
+ */
+static int get_struct_header(uint32_t structure_id, struct_header_t **header)
+{
+	unsigned int i, structure_count;
+	uintptr_t current_header;
+
+	assert(header);
+
+	structure_count = GET_SDS_REGION_STRUCTURE_COUNT(sds_mem_base);
+	if (structure_count == 0)
+		return SDS_ERR_STRUCT_NOT_FOUND;
+
+	current_header = ((uintptr_t)sds_mem_base) + SDS_REGION_DESC_SIZE;
+
+	/* Iterate over structure headers to find one with a matching ID */
+	for (i = 0; i < structure_count; i++) {
+		if (GET_SDS_HEADER_ID(current_header) == structure_id) {
+			*header = (struct_header_t *)current_header;
+			return SDS_OK;
+		}
+		current_header += GET_SDS_HEADER_STRUCT_SIZE(current_header) +
+						SDS_HEADER_SIZE;
+	}
+
+	*header = NULL;
+	return SDS_ERR_STRUCT_NOT_FOUND;
+}
+
+/*
+ * Check if a structure header corresponding to the structure ID exists.
+ * Returns SDS_OK if structure header exists else SDS_ERR_STRUCT_NOT_FOUND
+ * if not found.
+ */
+int sds_struct_exists(unsigned int structure_id)
+{
+	struct_header_t *header = NULL;
+	int ret;
+
+	ret = get_struct_header(structure_id, &header);
+	if (ret == SDS_OK) {
+		assert(header);
+	}
+
+	return ret;
+}
+
+/*
+ * Read from field in the structure corresponding to `structure_id`.
+ * `fld_off` is the offset to the field in the structure and `mode`
+ * indicates whether cache maintenance need to performed prior to the read.
+ * The `data` is the pointer to store the read data of size specified by `size`.
+ * Returns SDS_OK on success or corresponding error codes on failure.
+ */
+int sds_struct_read(uint32_t structure_id, unsigned int fld_off,
+		void *data, size_t size, sds_access_mode_t mode)
+{
+	int status;
+	uintptr_t field_base;
+	struct_header_t *header = NULL;
+
+	if (!data)
+		return SDS_ERR_INVALID_PARAMS;
+
+	/* Check if a structure with this ID exists */
+	status = get_struct_header(structure_id, &header);
+	if (status != SDS_OK)
+		return status;
+
+	assert(header);
+
+	if (mode == SDS_ACCESS_MODE_CACHED)
+		inv_dcache_range((uintptr_t)header, SDS_HEADER_SIZE + size);
+
+	if (!IS_SDS_HEADER_VALID(header)) {
+		WARN("SDS: Reading from un-finalized structure 0x%x\n",
+				structure_id);
+		return SDS_ERR_STRUCT_NOT_FINALIZED;
+	}
+
+	if ((fld_off + size) > GET_SDS_HEADER_STRUCT_SIZE(header))
+		return SDS_ERR_FAIL;
+
+	field_base = (uintptr_t)header + SDS_HEADER_SIZE + fld_off;
+	if (check_uptr_overflow(field_base, size - 1))
+		return SDS_ERR_FAIL;
+
+	/* Copy the required field in the struct */
+	memcpy(data, (void *)field_base, size);
+
+	return SDS_OK;
+}
+
+/*
+ * Write to the field in the structure corresponding to `structure_id`.
+ * `fld_off` is the offset to the field in the structure and `mode`
+ * indicates whether cache maintenance need to performed for the write.
+ * The `data` is the pointer to data of size specified by `size`.
+ * Returns SDS_OK on success or corresponding error codes on failure.
+ */
+int sds_struct_write(uint32_t structure_id, unsigned int fld_off,
+		void *data, size_t size, sds_access_mode_t mode)
+{
+	int status;
+	uintptr_t field_base;
+	struct_header_t *header = NULL;
+
+	if (!data)
+		return SDS_ERR_INVALID_PARAMS;
+
+	/* Check if a structure with this ID exists */
+	status = get_struct_header(structure_id, &header);
+	if (status != SDS_OK)
+		return status;
+
+	assert(header);
+
+	if (mode == SDS_ACCESS_MODE_CACHED)
+		inv_dcache_range((uintptr_t)header, SDS_HEADER_SIZE + size);
+
+	if (!IS_SDS_HEADER_VALID(header)) {
+		WARN("SDS: Writing to un-finalized structure 0x%x\n",
+				structure_id);
+		return SDS_ERR_STRUCT_NOT_FINALIZED;
+	}
+
+	if ((fld_off + size) > GET_SDS_HEADER_STRUCT_SIZE(header))
+		return SDS_ERR_FAIL;
+
+	field_base = (uintptr_t)header + SDS_HEADER_SIZE + fld_off;
+	if (check_uptr_overflow(field_base, size - 1))
+		return SDS_ERR_FAIL;
+
+	/* Copy the required field in the struct */
+	memcpy((void *)field_base, data, size);
+
+	if (mode == SDS_ACCESS_MODE_CACHED)
+		flush_dcache_range((uintptr_t)field_base, size);
+
+	return SDS_OK;
+}
+
+/*
+ * Initialize the SDS driver. Also verifies the SDS version and sanity of
+ * the SDS structure headers.
+ * Returns SDS_OK on success, SDS_ERR_FAIL on error.
+ */
+int sds_init(void)
+{
+	sds_mem_base = (uintptr_t)PLAT_ARM_SDS_MEM_BASE;
+
+	if (!IS_SDS_REGION_VALID(sds_mem_base)) {
+		WARN("SDS: No valid SDS Memory Region found\n");
+		return SDS_ERR_FAIL;
+	}
+
+	if (GET_SDS_REGION_SCHEMA_VERSION(sds_mem_base)
+				!= SDS_REGION_SCH_VERSION) {
+		WARN("SDS: Unsupported SDS schema version\n");
+		return SDS_ERR_FAIL;
+	}
+
+	sds_mem_size = GET_SDS_REGION_SIZE(sds_mem_base);
+	if (sds_mem_size > PLAT_ARM_SDS_MEM_SIZE_MAX) {
+		WARN("SDS: SDS Memory Region exceeds size limit\n");
+		return SDS_ERR_FAIL;
+	}
+
+	INFO("SDS: Detected SDS Memory Region (%zu bytes)\n", sds_mem_size);
+
+	if (validate_sds_struct_headers() != SDS_OK)
+		return SDS_ERR_FAIL;
+
+	return SDS_OK;
+}
diff --git a/drivers/arm/css/sds/sds_private.h b/drivers/arm/css/sds/sds_private.h
new file mode 100644
index 0000000..d801a04
--- /dev/null
+++ b/drivers/arm/css/sds/sds_private.h
@@ -0,0 +1,100 @@
+/*
+ * Copyright (c) 2017, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#ifndef SDS_PRIVATE_H
+#define SDS_PRIVATE_H
+
+/* SDS Header defines */
+#define SDS_HEADER_ID_SHIFT			0
+#define SDS_HEADER_ID_WIDTH			16
+#define SDS_HEADER_ID_MASK			((1 << SDS_HEADER_ID_WIDTH) - 1)
+
+#define SDS_HEADER_MINOR_VERSION_WIDTH		8
+#define SDS_HEADER_MINOR_VERSION_SHIFT		16
+#define SDS_HEADER_MAJOR_VERSION_WIDTH		8
+
+#define MAKE_SDS_HEADER_VERSION(major, minor)	\
+	(((((major) & 0xff) << SDS_HEADER_MINOR_VERSION_WIDTH) | ((minor) & 0xff)))
+#define SDS_HEADER_VERSION_MASK			\
+	((1 << (SDS_HEADER_MINOR_VERSION_WIDTH + SDS_HEADER_MAJOR_VERSION_WIDTH)) - 1)
+
+#define SDS_HEADER_VERSION			MAKE_SDS_HEADER_VERSION(1, 0)
+#define SDS_HEADER_STRUCT_SIZE_WIDTH		23
+#define SDS_HEADER_STRUCT_SIZE_SHIFT		1
+#define SDS_HEADER_STRUCT_SIZE_MASK		((1 << SDS_HEADER_STRUCT_SIZE_WIDTH) - 1)
+#define SDS_HEADER_VALID_MASK			0x1
+#define SDS_HEADER_VALID_SHIFT			0
+#define SDS_HEADER_SIZE				0x8
+
+/* Arbitrary, 16 bit value that indicates a valid SDS Memory Region */
+#define SDS_REGION_SIGNATURE			0xAA7A
+#define SDS_REGION_SIGNATURE_WIDTH		16
+#define SDS_REGION_SIGNATURE_SHIFT		0
+#define SDS_REGION_SIGNATURE_MASK		((1 << SDS_REGION_SIGNATURE_WIDTH) - 1)
+
+#define SDS_REGION_STRUCT_COUNT_SHIFT		16
+#define SDS_REGION_STRUCT_COUNT_WIDTH		8
+#define SDS_REGION_STRUCT_COUNT_MASK		((1 << SDS_REGION_STRUCT_COUNT_WIDTH) - 1)
+
+#define SDS_REGION_SCH_MINOR_SHIFT		24
+#define SDS_REGION_SCH_MINOR_WIDTH		4
+#define SDS_REGION_SCH_MINOR_MASK		((1 << SDS_REGION_SCH_MINOR_WIDTH) - 1)
+
+#define SDS_REGION_SCH_MAJOR_SHIFT		28
+#define SDS_REGION_SCH_MAJOR_WIDTH		4
+#define SDS_REGION_SCH_MAJOR_MASK		((1 << SDS_REGION_SCH_MAJOR_WIDTH) - 1)
+
+#define SDS_REGION_SCH_VERSION_MASK		\
+	((1 << (SDS_REGION_SCH_MINOR_WIDTH + SDS_REGION_SCH_MAJOR_WIDTH)) - 1)
+
+#define MAKE_SDS_REGION_SCH_VERSION(maj, min)	\
+	((((maj) & SDS_REGION_SCH_MAJOR_MASK) << SDS_REGION_SCH_MINOR_WIDTH) |	\
+	((min) & SDS_REGION_SCH_MINOR_MASK))
+
+#define SDS_REGION_SCH_VERSION			MAKE_SDS_REGION_SCH_VERSION(1, 0)
+#define SDS_REGION_REGIONSIZE_OFFSET		0x4
+#define SDS_REGION_DESC_SIZE			0x8
+
+#ifndef __ASSEMBLER__
+#include <stddef.h>
+#include <stdint.h>
+
+/* Header containing Shared Data Structure metadata */
+typedef struct structure_header {
+	uint32_t reg[2];
+} struct_header_t;
+
+#define GET_SDS_HEADER_ID(_header)			\
+	((((struct_header_t *)(_header))->reg[0]) & SDS_HEADER_ID_MASK)
+#define GET_SDS_HEADER_VERSION(_header)			\
+	(((((struct_header_t *)(_header))->reg[0]) >> SDS_HEADER_MINOR_VERSION_SHIFT)\
+	& SDS_HEADER_VERSION_MASK)
+#define GET_SDS_HEADER_STRUCT_SIZE(_header)		\
+	(((((struct_header_t *)(_header))->reg[1]) >> SDS_HEADER_STRUCT_SIZE_SHIFT)\
+	& SDS_HEADER_STRUCT_SIZE_MASK)
+#define IS_SDS_HEADER_VALID(_header)			\
+	((((struct_header_t *)(_header))->reg[1]) & SDS_HEADER_VALID_MASK)
+#define GET_SDS_STRUCT_FIELD(_header, _field_offset)	\
+	((((uint8_t *)(_header)) + sizeof(struct_header_t)) + (_field_offset))
+
+/* Region Descriptor describing the SDS Memory Region */
+typedef struct region_descriptor {
+	uint32_t reg[2];
+} region_desc_t;
+
+#define IS_SDS_REGION_VALID(region)			\
+	(((((region_desc_t *)(region))->reg[0]) & SDS_REGION_SIGNATURE_MASK) == SDS_REGION_SIGNATURE)
+#define GET_SDS_REGION_STRUCTURE_COUNT(region)		\
+	(((((region_desc_t *)(region))->reg[0]) >> SDS_REGION_STRUCT_COUNT_SHIFT)\
+	& SDS_REGION_STRUCT_COUNT_MASK)
+#define GET_SDS_REGION_SCHEMA_VERSION(region)		\
+	(((((region_desc_t *)(region))->reg[0]) >> SDS_REGION_SCH_MINOR_SHIFT)\
+	& SDS_REGION_SCH_VERSION_MASK)
+#define GET_SDS_REGION_SIZE(region)		((((region_desc_t *)(region))->reg[1]))
+
+#endif /* __ASSEMBLER__ */
+
+#endif /* SDS_PRIVATE_H */