drivers/scmi-msg: support for clock protocol

Adds SCMI clock protocol support in the SCMI message drivers as
defined in SCMI specification v2.0 [1] for clock protocol messages.

Platform can provide one of the plat_scmi_clock_*() handler for the
supported operations set/get state/rate and others.

scmi_msg_get_clock_handler() sanitizes the message_id value
against any speculative use of clock ID as a index since by
SCMI specification, IDs are indices.

This implementation is based on the OP-TEE project implementation [2]
itself based on the SCP-firmware implementation [3] of the SCMI
protocol server side.

Link: [1] http://infocenter.arm.com/help/topic/com.arm.doc.den0056a/DEN0056A_System_Control_and_Management_Interface.pdf
Link: [2] https://github.com/OP-TEE/optee_os/commit/a7a9e3ba71dd908aafdc4c5ed9b29b15faa9692d
Link: [3] https://github.com/ARM-software/SCP-firmware.git



Change-Id: Ib56e096512042d4f7b9563d1e4181554eb8ed02c
Signed-off-by: Etienne Carriere <etienne.carriere@linaro.org>

drivers/st/scmi-msg/clock.c

+// SPDX-License-Identifier: BSD-3-Clause
+/*
+ * Copyright (c) 2015-2020, Arm Limited and Contributors. All rights reserved.
+ * Copyright (c) 2019-2020, Linaro Limited
+ */
+#include <cdefs.h>
+#include <string.h>
+
+#include <drivers/st/scmi-msg.h>
+#include <drivers/st/scmi.h>
+#include <lib/utils_def.h>
+
+#include "common.h"
+
+#pragma weak plat_scmi_clock_count
+#pragma weak plat_scmi_clock_get_name
+#pragma weak plat_scmi_clock_rates_array
+#pragma weak plat_scmi_clock_rates_by_step
+#pragma weak plat_scmi_clock_get_rate
+#pragma weak plat_scmi_clock_set_rate
+#pragma weak plat_scmi_clock_get_state
+#pragma weak plat_scmi_clock_set_state
+
+static bool message_id_is_supported(unsigned int message_id);
+
+size_t plat_scmi_clock_count(unsigned int agent_id __unused)
+{
+	return 0U;
+}
+
+const char *plat_scmi_clock_get_name(unsigned int agent_id __unused,
+				     unsigned int scmi_id __unused)
+{
+	return NULL;
+}
+
+int32_t plat_scmi_clock_rates_array(unsigned int agent_id __unused,
+				    unsigned int scmi_id __unused,
+				    unsigned long *rates __unused,
+				    size_t *nb_elts __unused)
+{
+	return SCMI_NOT_SUPPORTED;
+}
+
+int32_t plat_scmi_clock_rates_by_step(unsigned int agent_id __unused,
+				      unsigned int scmi_id __unused,
+				      unsigned long *steps __unused)
+{
+	return SCMI_NOT_SUPPORTED;
+}
+
+unsigned long plat_scmi_clock_get_rate(unsigned int agent_id __unused,
+				       unsigned int scmi_id __unused)
+{
+	return 0U;
+}
+
+int32_t plat_scmi_clock_set_rate(unsigned int agent_id __unused,
+				 unsigned int scmi_id __unused,
+				 unsigned long rate __unused)
+{
+	return SCMI_NOT_SUPPORTED;
+}
+
+int32_t plat_scmi_clock_get_state(unsigned int agent_id __unused,
+				  unsigned int scmi_id __unused)
+{
+	return SCMI_NOT_SUPPORTED;
+}
+
+int32_t plat_scmi_clock_set_state(unsigned int agent_id __unused,
+				  unsigned int scmi_id __unused,
+				  bool enable_not_disable __unused)
+{
+	return SCMI_NOT_SUPPORTED;
+}
+
+static void report_version(struct scmi_msg *msg)
+{
+	struct scmi_protocol_version_p2a return_values = {
+		.status = SCMI_SUCCESS,
+		.version = SCMI_PROTOCOL_VERSION_CLOCK,
+	};
+
+	if (msg->in_size != 0) {
+		scmi_status_response(msg, SCMI_PROTOCOL_ERROR);
+		return;
+	}
+
+	scmi_write_response(msg, &return_values, sizeof(return_values));
+}
+
+static void report_attributes(struct scmi_msg *msg)
+{
+	size_t agent_count = plat_scmi_clock_count(msg->agent_id);
+	struct scmi_protocol_attributes_p2a return_values = {
+		.status = SCMI_SUCCESS,
+		.attributes = SCMI_CLOCK_PROTOCOL_ATTRIBUTES(1U, agent_count),
+	};
+
+	if (msg->in_size != 0) {
+		scmi_status_response(msg, SCMI_PROTOCOL_ERROR);
+		return;
+	}
+
+	scmi_write_response(msg, &return_values, sizeof(return_values));
+}
+
+static void report_message_attributes(struct scmi_msg *msg)
+{
+	struct scmi_protocol_message_attributes_a2p *in_args = (void *)msg->in;
+	struct scmi_protocol_message_attributes_p2a return_values = {
+		.status = SCMI_SUCCESS,
+		/* For this protocol, attributes shall be zero */
+		.attributes = 0U,
+	};
+
+	if (msg->in_size != sizeof(*in_args)) {
+		scmi_status_response(msg, SCMI_PROTOCOL_ERROR);
+		return;
+	}
+
+	if (!message_id_is_supported(in_args->message_id)) {
+		scmi_status_response(msg, SCMI_NOT_FOUND);
+		return;
+	}
+
+	scmi_write_response(msg, &return_values, sizeof(return_values));
+}
+
+static void scmi_clock_attributes(struct scmi_msg *msg)
+{
+	const struct scmi_clock_attributes_a2p *in_args = (void *)msg->in;
+	struct scmi_clock_attributes_p2a return_values = {
+		.status = SCMI_SUCCESS,
+	};
+	const char *name = NULL;
+	unsigned int clock_id = 0U;
+
+	if (msg->in_size != sizeof(*in_args)) {
+		scmi_status_response(msg, SCMI_PROTOCOL_ERROR);
+		return;
+	}
+
+	clock_id = SPECULATION_SAFE_VALUE(in_args->clock_id);
+
+	if (clock_id >= plat_scmi_clock_count(msg->agent_id)) {
+		scmi_status_response(msg, SCMI_INVALID_PARAMETERS);
+		return;
+	}
+
+
+	name = plat_scmi_clock_get_name(msg->agent_id, clock_id);
+	if (name == NULL) {
+		scmi_status_response(msg, SCMI_NOT_FOUND);
+		return;
+	}
+
+	COPY_NAME_IDENTIFIER(return_values.clock_name, name);
+
+	return_values.attributes = plat_scmi_clock_get_state(msg->agent_id,
+							     clock_id);
+
+	scmi_write_response(msg, &return_values, sizeof(return_values));
+}
+
+static void scmi_clock_rate_get(struct scmi_msg *msg)
+{
+	const struct scmi_clock_rate_get_a2p *in_args = (void *)msg->in;
+	unsigned long rate = 0U;
+	struct scmi_clock_rate_get_p2a return_values = {
+		.status = SCMI_SUCCESS,
+	};
+	unsigned int clock_id = 0U;
+
+	if (msg->in_size != sizeof(*in_args)) {
+		scmi_status_response(msg, SCMI_PROTOCOL_ERROR);
+		return;
+	}
+
+	clock_id = SPECULATION_SAFE_VALUE(in_args->clock_id);
+
+	if (clock_id >= plat_scmi_clock_count(msg->agent_id)) {
+		scmi_status_response(msg, SCMI_INVALID_PARAMETERS);
+		return;
+	}
+
+	rate = plat_scmi_clock_get_rate(msg->agent_id, clock_id);
+
+	return_values.rate[0] = (uint32_t)rate;
+	return_values.rate[1] = (uint32_t)((uint64_t)rate >> 32);
+
+	scmi_write_response(msg, &return_values, sizeof(return_values));
+}
+
+static void scmi_clock_rate_set(struct scmi_msg *msg)
+{
+	const struct scmi_clock_rate_set_a2p *in_args = (void *)msg->in;
+	unsigned long rate = 0U;
+	int32_t status = 0;
+	unsigned int clock_id = 0U;
+
+	if (msg->in_size != sizeof(*in_args)) {
+		scmi_status_response(msg, SCMI_PROTOCOL_ERROR);
+		return;
+	}
+
+	clock_id = SPECULATION_SAFE_VALUE(in_args->clock_id);
+
+	if (clock_id >= plat_scmi_clock_count(msg->agent_id)) {
+		scmi_status_response(msg, SCMI_INVALID_PARAMETERS);
+		return;
+	}
+
+	rate = (unsigned long)(((uint64_t)in_args->rate[1] << 32) |
+			       in_args->rate[0]);
+
+	status = plat_scmi_clock_set_rate(msg->agent_id, clock_id, rate);
+
+	scmi_status_response(msg, status);
+}
+
+static void scmi_clock_config_set(struct scmi_msg *msg)
+{
+	const struct scmi_clock_config_set_a2p *in_args = (void *)msg->in;
+	int32_t status = SCMI_GENERIC_ERROR;
+	bool enable = false;
+	unsigned int clock_id = 0U;
+
+	if (msg->in_size != sizeof(*in_args)) {
+		scmi_status_response(msg, SCMI_PROTOCOL_ERROR);
+		return;
+	}
+
+	clock_id = SPECULATION_SAFE_VALUE(in_args->clock_id);
+
+	if (clock_id >= plat_scmi_clock_count(msg->agent_id)) {
+		scmi_status_response(msg, SCMI_INVALID_PARAMETERS);
+		return;
+	}
+
+	enable = in_args->attributes & SCMI_CLOCK_CONFIG_SET_ENABLE_MASK;
+
+	status = plat_scmi_clock_set_state(msg->agent_id, clock_id, enable);
+
+	scmi_status_response(msg, status);
+}
+
+#define RATES_ARRAY_SIZE_MAX	(SCMI_PLAYLOAD_MAX - \
+				 sizeof(struct scmi_clock_describe_rates_p2a))
+
+#define SCMI_RATES_BY_ARRAY(_nb_rates, _rem_rates) \
+	SCMI_CLOCK_DESCRIBE_RATES_NUM_RATES_FLAGS((_nb_rates), \
+						SCMI_CLOCK_RATE_FORMAT_LIST, \
+						(_rem_rates))
+#define SCMI_RATES_BY_STEP \
+	SCMI_CLOCK_DESCRIBE_RATES_NUM_RATES_FLAGS(3U, \
+						SCMI_CLOCK_RATE_FORMAT_RANGE, \
+						0U)
+
+#define RATE_DESC_SIZE		sizeof(struct scmi_clock_rate)
+
+static void write_rate_desc_array_in_buffer(char *dest, unsigned long *rates,
+					    size_t nb_elt)
+{
+	uint32_t *out = (uint32_t *)(uintptr_t)dest;
+	size_t n;
+
+	ASSERT_SYM_PTR_ALIGN(out);
+
+	for (n = 0U; n < nb_elt; n++) {
+		out[2 * n] = (uint32_t)rates[n];
+		out[2 * n + 1] = (uint32_t)((uint64_t)rates[n] >> 32);
+	}
+}
+
+static void scmi_clock_describe_rates(struct scmi_msg *msg)
+{
+	const struct scmi_clock_describe_rates_a2p *in_args = (void *)msg->in;
+	struct scmi_clock_describe_rates_p2a p2a = {
+		.status = SCMI_SUCCESS,
+	};
+	size_t nb_rates;
+	int32_t status;
+	unsigned int clock_id;
+
+	if (msg->in_size != sizeof(*in_args)) {
+		scmi_status_response(msg, SCMI_PROTOCOL_ERROR);
+		return;
+	}
+
+	clock_id = SPECULATION_SAFE_VALUE(in_args->clock_id);
+
+	if (clock_id >= plat_scmi_clock_count(msg->agent_id)) {
+		scmi_status_response(msg, SCMI_INVALID_PARAMETERS);
+		return;
+	}
+
+	/* Platform may support array rate description */
+	status = plat_scmi_clock_rates_array(msg->agent_id, clock_id, NULL,
+					     &nb_rates);
+	if (status == SCMI_SUCCESS) {
+		/* Currently 12 cells mex, so it's affordable for the stack */
+		unsigned long plat_rates[RATES_ARRAY_SIZE_MAX / RATE_DESC_SIZE];
+		size_t max_nb = RATES_ARRAY_SIZE_MAX / RATE_DESC_SIZE;
+		size_t ret_nb = MIN(nb_rates - in_args->rate_index, max_nb);
+		size_t rem_nb = nb_rates - in_args->rate_index - ret_nb;
+
+		status =  plat_scmi_clock_rates_array(msg->agent_id, clock_id,
+						      plat_rates, &ret_nb);
+		if (status == SCMI_SUCCESS) {
+			write_rate_desc_array_in_buffer(msg->out + sizeof(p2a),
+							plat_rates, ret_nb);
+
+			p2a.num_rates_flags = SCMI_RATES_BY_ARRAY(ret_nb,
+								  rem_nb);
+			p2a.status = SCMI_SUCCESS;
+
+			memcpy(msg->out, &p2a, sizeof(p2a));
+			msg->out_size_out = sizeof(p2a) +
+					    ret_nb * RATE_DESC_SIZE;
+		}
+	} else if (status == SCMI_NOT_SUPPORTED) {
+		unsigned long triplet[3] = { 0U, 0U, 0U };
+
+		/* Platform may support min§max/step triplet description */
+		status =  plat_scmi_clock_rates_by_step(msg->agent_id, clock_id,
+							triplet);
+		if (status == SCMI_SUCCESS) {
+			write_rate_desc_array_in_buffer(msg->out + sizeof(p2a),
+							triplet, 3U);
+
+			p2a.num_rates_flags = SCMI_RATES_BY_STEP;
+			p2a.status = SCMI_SUCCESS;
+
+			memcpy(msg->out, &p2a, sizeof(p2a));
+			msg->out_size_out = sizeof(p2a) + (3U * RATE_DESC_SIZE);
+		}
+	} else {
+		/* Fallthrough generic exit sequence below with error status */
+	}
+
+	if (status != SCMI_SUCCESS) {
+		scmi_status_response(msg, status);
+	} else {
+		/*
+		 * Message payload is already writen to msg->out, and
+		 * msg->out_size_out updated.
+		 */
+	}
+}
+
+static const scmi_msg_handler_t scmi_clock_handler_table[] = {
+	[SCMI_PROTOCOL_VERSION] = report_version,
+	[SCMI_PROTOCOL_ATTRIBUTES] = report_attributes,
+	[SCMI_PROTOCOL_MESSAGE_ATTRIBUTES] = report_message_attributes,
+	[SCMI_CLOCK_ATTRIBUTES] = scmi_clock_attributes,
+	[SCMI_CLOCK_DESCRIBE_RATES] = scmi_clock_describe_rates,
+	[SCMI_CLOCK_RATE_SET] = scmi_clock_rate_set,
+	[SCMI_CLOCK_RATE_GET] = scmi_clock_rate_get,
+	[SCMI_CLOCK_CONFIG_SET] = scmi_clock_config_set,
+};
+
+static bool message_id_is_supported(size_t message_id)
+{
+	return (message_id < ARRAY_SIZE(scmi_clock_handler_table)) &&
+	       (scmi_clock_handler_table[message_id] != NULL);
+}
+
+scmi_msg_handler_t scmi_msg_get_clock_handler(struct scmi_msg *msg)
+{
+	const size_t array_size = ARRAY_SIZE(scmi_clock_handler_table);
+	unsigned int message_id = SPECULATION_SAFE_VALUE(msg->message_id);
+
+	if (message_id >= array_size) {
+		VERBOSE("Clock handle not found %u", msg->message_id);
+		return NULL;
+	}
+
+	return scmi_clock_handler_table[message_id];
+}

drivers/st/scmi-msg/clock.h

+/* SPDX-License-Identifier: BSD-3-Clause */
+/*
+ * Copyright (c) 2015-2019, Arm Limited and Contributors. All rights reserved.
+ * Copyright (c) 2019, Linaro Limited
+ */
+
+#ifndef SCMI_MSG_CLOCK_H
+#define SCMI_MSG_CLOCK_H
+
+#include <stdint.h>
+
+#include <lib/utils_def.h>
+
+#define SCMI_PROTOCOL_VERSION_CLOCK	0x20000U
+
+/*
+ * Identifiers of the SCMI Clock Management Protocol commands
+ */
+enum scmi_clock_command_id {
+	SCMI_CLOCK_ATTRIBUTES = 0x003,
+	SCMI_CLOCK_DESCRIBE_RATES = 0x004,
+	SCMI_CLOCK_RATE_SET = 0x005,
+	SCMI_CLOCK_RATE_GET = 0x006,
+	SCMI_CLOCK_CONFIG_SET = 0x007,
+};
+
+/* Protocol attributes */
+#define SCMI_CLOCK_CLOCK_COUNT_MASK			GENMASK(15, 0)
+#define SCMI_CLOCK_MAX_PENDING_TRANSITIONS_MASK		GENMASK(23, 16)
+
+#define SCMI_CLOCK_PROTOCOL_ATTRIBUTES(_max_pending, _clk_count) \
+	((((_max_pending) << 16) & SCMI_CLOCK_MAX_PENDING_TRANSITIONS_MASK) | \
+	 (((_clk_count) & SCMI_CLOCK_CLOCK_COUNT_MASK)))
+
+struct scmi_clock_attributes_a2p {
+	uint32_t clock_id;
+};
+
+#define SCMI_CLOCK_NAME_LENGTH_MAX	16U
+
+struct scmi_clock_attributes_p2a {
+	int32_t status;
+	uint32_t attributes;
+	char clock_name[SCMI_CLOCK_NAME_LENGTH_MAX];
+};
+
+/*
+ * Clock Rate Get
+ */
+
+struct scmi_clock_rate_get_a2p {
+	uint32_t clock_id;
+};
+
+struct scmi_clock_rate_get_p2a {
+	int32_t status;
+	uint32_t rate[2];
+};
+
+/*
+ * Clock Rate Set
+ */
+
+/* If set, set the new clock rate asynchronously */
+#define SCMI_CLOCK_RATE_SET_ASYNC_POS			0
+/* If set, do not send a delayed asynchronous response */
+#define SCMI_CLOCK_RATE_SET_NO_DELAYED_RESPONSE_POS	1
+/* Round up, if set, otherwise round down */
+#define SCMI_CLOCK_RATE_SET_ROUND_UP_POS		2
+/* If set, the platform chooses the appropriate rounding mode */
+#define SCMI_CLOCK_RATE_SET_ROUND_AUTO_POS		3
+
+#define SCMI_CLOCK_RATE_SET_ASYNC_MASK \
+		BIT(SCMI_CLOCK_RATE_SET_ASYNC_POS)
+#define SCMI_CLOCK_RATE_SET_NO_DELAYED_RESPONSE_MASK \
+		BIT(SCMI_CLOCK_RATE_SET_NO_DELAYED_RESPONSE_POS)
+#define SCMI_CLOCK_RATE_SET_ROUND_UP_MASK \
+		BIT(SCMI_CLOCK_RATE_SET_ROUND_UP_POS)
+#define SCMI_CLOCK_RATE_SET_ROUND_AUTO_MASK \
+		BIT(SCMI_CLOCK_RATE_SET_ROUND_AUTO_POS)
+
+struct scmi_clock_rate_set_a2p {
+	uint32_t flags;
+	uint32_t clock_id;
+	uint32_t rate[2];
+};
+
+struct scmi_clock_rate_set_p2a {
+	int32_t status;
+};
+
+/*
+ * Clock Config Set
+ */
+
+#define SCMI_CLOCK_CONFIG_SET_ENABLE_POS	0
+
+#define SCMI_CLOCK_CONFIG_SET_ENABLE_MASK \
+	BIT(SCMI_CLOCK_CONFIG_SET_ENABLE_POS)
+
+struct scmi_clock_config_set_a2p {
+	uint32_t clock_id;
+	uint32_t attributes;
+};
+
+struct scmi_clock_config_set_p2a {
+	int32_t status;
+};
+
+/*
+ * Clock Describe Rates
+ */
+
+#define SCMI_CLOCK_RATE_FORMAT_RANGE			1U
+#define SCMI_CLOCK_RATE_FORMAT_LIST			0U
+
+#define SCMI_CLOCK_DESCRIBE_RATES_REMAINING_MASK	GENMASK_32(31, 16)
+#define SCMI_CLOCK_DESCRIBE_RATES_REMAINING_POS		16
+
+#define SCMI_CLOCK_DESCRIBE_RATES_FORMAT_MASK		BIT(12)
+#define SCMI_CLOCK_DESCRIBE_RATES_FORMAT_POS		12
+
+#define SCMI_CLOCK_DESCRIBE_RATES_COUNT_MASK		GENMASK_32(11, 0)
+
+#define SCMI_CLOCK_DESCRIBE_RATES_NUM_RATES_FLAGS(_count, _fmt, _rem_rates) \
+	( \
+		((_count) & SCMI_CLOCK_DESCRIBE_RATES_COUNT_MASK) | \
+		(((_rem_rates) << SCMI_CLOCK_DESCRIBE_RATES_REMAINING_POS) & \
+		 SCMI_CLOCK_DESCRIBE_RATES_REMAINING_MASK) | \
+		(((_fmt) << SCMI_CLOCK_DESCRIBE_RATES_FORMAT_POS) & \
+		 SCMI_CLOCK_DESCRIBE_RATES_FORMAT_MASK) \
+	)
+
+struct scmi_clock_rate {
+	uint32_t low;
+	uint32_t high;
+};
+
+struct scmi_clock_describe_rates_a2p {
+	uint32_t clock_id;
+	uint32_t rate_index;
+};
+
+struct scmi_clock_describe_rates_p2a {
+	int32_t status;
+	uint32_t num_rates_flags;
+	struct scmi_clock_rate rates[];
+};
+
+#endif /* SCMI_MSG_CLOCK_H */

drivers/st/scmi-msg/common.h

@@ -12,6 +12,7 @@
 #include <string.h>
 
 #include "base.h"
+#include "clock.h"
 
 #define SCMI_VERSION			0x20000U
 #define SCMI_IMPL_VERSION		0U
@@ -94,6 +95,13 @@ typedef void (*scmi_msg_handler_t)(struct scmi_msg *msg);
  */
 scmi_msg_handler_t scmi_msg_get_base_handler(struct scmi_msg *msg);
 
+/*
+ * scmi_msg_get_clock_handler - Return a handler for a clock message
+ * @msg - message to process
+ * Return a function handler for the message or NULL
+ */
+scmi_msg_handler_t scmi_msg_get_clock_handler(struct scmi_msg *msg);
+
 /*
  * Process Read, process and write response for input SCMI message
  *

drivers/st/scmi-msg/entry.c

@@ -41,6 +41,9 @@ void scmi_process_message(struct scmi_msg *msg)
 	case SCMI_PROTOCOL_ID_BASE:
 		handler = scmi_msg_get_base_handler(msg);
 		break;
+	case SCMI_PROTOCOL_ID_CLOCK:
+		handler = scmi_msg_get_clock_handler(msg);
+		break;
 	default:
 		break;
 	}

include/drivers/st/scmi-msg.h

@@ -62,4 +62,83 @@ const char *plat_scmi_vendor_name(void);
 /* Get the name of the SCMI sub-vendor for the platform */
 const char *plat_scmi_sub_vendor_name(void);
 
+/* Handlers for SCMI Clock protocol services */
+
+/*
+ * Return number of clock controllers for an agent
+ * @agent_id: SCMI agent ID
+ * Return number of clock controllers
+ */
+size_t plat_scmi_clock_count(unsigned int agent_id);
+
+/*
+ * Get clock controller string ID (aka name)
+ * @agent_id: SCMI agent ID
+ * @scmi_id: SCMI clock ID
+ * Return pointer to name or NULL
+ */
+const char *plat_scmi_clock_get_name(unsigned int agent_id,
+				     unsigned int scmi_id);
+
+/*
+ * Get clock possible rate as an array of frequencies in Hertz.
+ *
+ * @agent_id: SCMI agent ID
+ * @scmi_id: SCMI clock ID
+ * @rates: If NULL, function returns, else output rates array
+ * @nb_elts: Array size of @rates.
+ * Return an SCMI compliant error code
+ */
+int32_t plat_scmi_clock_rates_array(unsigned int agent_id, unsigned int scmi_id,
+				    unsigned long *rates, size_t *nb_elts);
+
+/*
+ * Get clock possible rate as range with regular steps in Hertz
+ *
+ * @agent_id: SCMI agent ID
+ * @scmi_id: SCMI clock ID
+ * @min_max_step: 3 cell array for min, max and step rate data
+ * Return an SCMI compliant error code
+ */
+int32_t plat_scmi_clock_rates_by_step(unsigned int agent_id,
+				      unsigned int scmi_id,
+				      unsigned long *min_max_step);
+
+/*
+ * Get clock rate in Hertz
+ * @agent_id: SCMI agent ID
+ * @scmi_id: SCMI clock ID
+ * Return clock rate or 0 if not supported
+ */
+unsigned long plat_scmi_clock_get_rate(unsigned int agent_id,
+				       unsigned int scmi_id);
+
+/*
+ * Set clock rate in Hertz
+ * @agent_id: SCMI agent ID
+ * @scmi_id: SCMI clock ID
+ * @rate: Target clock frequency in Hertz
+ * Return a compliant SCMI error code
+ */
+int32_t plat_scmi_clock_set_rate(unsigned int agent_id, unsigned int scmi_id,
+				 unsigned long rate);
+
+/*
+ * Get clock state (enabled or disabled)
+ * @agent_id: SCMI agent ID
+ * @scmi_id: SCMI clock ID
+ * Return 1 if clock is enabled, 0 if disables, or a negative SCMI error code
+ */
+int32_t plat_scmi_clock_get_state(unsigned int agent_id, unsigned int scmi_id);
+
+/*
+ * Get clock state (enabled or disabled)
+ * @agent_id: SCMI agent ID
+ * @scmi_id: SCMI clock ID
+ * @enable_not_disable: Enable clock if true, disable clock otherwise
+ * Return a compliant SCMI error code
+ */
+int32_t plat_scmi_clock_set_state(unsigned int agent_id, unsigned int scmi_id,
+				  bool enable_not_disable);
+
 #endif /* SCMI_MSG_H */