firmware: scmi: add support for clock management protocol

This includes:
	1) Source containing helper functions, each
	implementing a command from the clock management
	protocol.

	2) A clock controller driver making use of said
	helper functions and implementing the clock
	subsystem API.

	3) A DT binding for clock protocol node.

Signed-off-by: Laurentiu Mihalcea <[email protected]>

drivers/clock_control/CMakeLists.txt

@@ -4,6 +4,7 @@ zephyr_library()
 
 zephyr_library_sources_ifdef(CONFIG_CLOCK_CONTROL_BEETLE              beetle_clock_control.c)
 zephyr_library_sources_ifdef(CONFIG_CLOCK_CONTROL_ADSP                clock_control_adsp.c)
+zephyr_library_sources_ifdef(CONFIG_CLOCK_CONTROL_ARM_SCMI            clock_control_arm_scmi.c)
 zephyr_library_sources_ifdef(CONFIG_CLOCK_CONTROL_ESP32               clock_control_esp32.c)
 zephyr_library_sources_ifdef(CONFIG_CLOCK_CONTROL_FIXED_RATE_CLOCK    clock_control_fixed_rate.c)
 zephyr_library_sources_ifdef(CONFIG_CLOCK_CONTROL_GD32                clock_control_gd32.c)

drivers/clock_control/Kconfig

@@ -94,4 +94,6 @@ source "drivers/clock_control/Kconfig.rpi_pico"
 
 source "drivers/clock_control/Kconfig.nrf_auxpll"
 
+source "drivers/clock_control/Kconfig.arm_scmi"
+
 endif # CLOCK_CONTROL

drivers/clock_control/Kconfig.arm_scmi

@@ -0,0 +1,8 @@
+# Copyright 2024 NXP
+
+config CLOCK_CONTROL_ARM_SCMI
+	bool "SCMI clock protocol clock controller driver"
+	default y
+	depends on ARM_SCMI_CLK_HELPERS
+	help
+	  Enable support for SCMI-based clock control.

drivers/clock_control/clock_control_arm_scmi.c

@@ -0,0 +1,102 @@
+/*
+ * Copyright 2024 NXP
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <zephyr/drivers/firmware/scmi/clk.h>
+#include <zephyr/drivers/clock_control.h>
+#include <zephyr/logging/log.h>
+
+LOG_MODULE_REGISTER(arm_scmi_clock);
+
+#define DT_DRV_COMPAT arm_scmi_clock
+
+struct scmi_clock_data {
+	uint32_t clk_num;
+};
+
+static int scmi_clock_on_off(const struct device *dev,
+			     clock_control_subsys_t clk, bool on)
+{
+	struct scmi_clock_data *data;
+	struct scmi_protocol *proto;
+	uint32_t clk_id;
+	struct scmi_clock_config cfg;
+
+	proto = dev->data;
+	data = proto->data;
+	clk_id = POINTER_TO_UINT(clk);
+
+	if (clk_id >= data->clk_num) {
+		return -EINVAL;
+	}
+
+	memset(&cfg, 0, sizeof(cfg));
+
+	cfg.attributes = SCMI_CLK_CONFIG_ENABLE_DISABLE(on);
+	cfg.clk_id = clk_id;
+
+	return scmi_clock_config_set(proto, &cfg);
+}
+
+static int scmi_clock_on(const struct device *dev, clock_control_subsys_t clk)
+{
+	return scmi_clock_on_off(dev, clk, true);
+}
+
+static int scmi_clock_off(const struct device *dev, clock_control_subsys_t clk)
+{
+	return scmi_clock_on_off(dev, clk, false);
+}
+
+static int scmi_clock_get_rate(const struct device *dev,
+			       clock_control_subsys_t clk, uint32_t *rate)
+{
+	struct scmi_clock_data *data;
+	struct scmi_protocol *proto;
+	uint32_t clk_id;
+
+	proto = dev->data;
+	data = proto->data;
+	clk_id = POINTER_TO_UINT(clk);
+
+	if (clk_id >= data->clk_num) {
+		return -EINVAL;
+	}
+
+	return scmi_clock_rate_get(proto, clk_id, rate);
+}
+
+static struct clock_control_driver_api scmi_clock_api = {
+	.on = scmi_clock_on,
+	.off = scmi_clock_off,
+	.get_rate = scmi_clock_get_rate,
+};
+
+static int scmi_clock_init(const struct device *dev)
+{
+	struct scmi_protocol *proto;
+	struct scmi_clock_data *data;
+	int ret;
+	uint32_t attributes;
+
+	proto = dev->data;
+	data = proto->data;
+
+	ret = scmi_clock_protocol_attributes(proto, &attributes);
+	if (ret < 0) {
+		LOG_ERR("failed to fetch clock attributes: %d", ret);
+		return ret;
+	}
+
+	data->clk_num = SCMI_CLK_ATTRIBUTES_CLK_NUM(attributes);
+
+	return 0;
+}
+
+static struct scmi_clock_data data;
+
+DT_INST_SCMI_PROTOCOL_DEFINE(0, &scmi_clock_init, NULL, &data, NULL,
+			     PRE_KERNEL_1, CONFIG_CLOCK_CONTROL_INIT_PRIORITY,
+			     &scmi_clock_api);

drivers/firmware/scmi/CMakeLists.txt

@@ -6,3 +6,6 @@ zephyr_library()
 zephyr_library_sources_ifdef(CONFIG_ARM_SCMI core.c)
 zephyr_library_sources_ifdef(CONFIG_ARM_SCMI_MAILBOX_TRANSPORT mailbox.c)
 zephyr_library_sources_ifdef(CONFIG_ARM_SCMI_SHMEM shmem.c)
+
+# SCMI protocol helper files
+zephyr_library_sources_ifdef(CONFIG_ARM_SCMI_CLK_HELPERS clk.c)

drivers/firmware/scmi/Kconfig

@@ -3,6 +3,13 @@
 
 if ARM_SCMI
 
+config ARM_SCMI_CLK_HELPERS
+	bool "Helper functions for SCMI clock protocol"
+	default y
+	depends on DT_HAS_ARM_SCMI_CLOCK_ENABLED
+	help
+	  Enable support for SCMI clock protocol helper functions.
+
 config ARM_SCMI_MAILBOX_TRANSPORT
 	bool "SCMI transport based on shared memory and doorbells"
 	default y

drivers/firmware/scmi/clk.c

@@ -0,0 +1,152 @@
+/*
+ * Copyright 2024 NXP
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <zephyr/drivers/firmware/scmi/clk.h>
+#include <string.h>
+
+/* TODO: if extended attributes are supported this should be moved
+ * to the header file so that users will have access to it.
+ */
+#define SCMI_CLK_CONFIG_EA_MASK GENMASK(23, 16)
+
+struct scmi_clock_attributes_reply {
+	int32_t status;
+	uint32_t attributes;
+};
+
+struct scmi_clock_rate_set_reply {
+	int32_t status;
+	uint32_t rate[2];
+};
+
+int scmi_clock_rate_get(struct scmi_protocol *proto,
+			uint32_t clk_id, uint32_t *rate)
+{
+	struct scmi_message msg, reply;
+	int ret;
+	struct scmi_clock_rate_set_reply reply_buffer;
+
+	/* sanity checks */
+	if (!proto || !rate) {
+		return -EINVAL;
+	}
+
+	if (proto->id != SCMI_PROTOCOL_CLOCK) {
+		return -EINVAL;
+	}
+
+	msg.hdr = SCMI_MESSAGE_HDR_MAKE(SCMI_CLK_MSG_CLOCK_RATE_GET,
+					SCMI_COMMAND, proto->id, 0x0);
+	msg.len = sizeof(clk_id);
+	msg.content = &clk_id;
+
+	reply.hdr = msg.hdr;
+	reply.len = sizeof(reply_buffer);
+	reply.content = &reply_buffer;
+
+	ret = scmi_send_message(proto, &msg, &reply);
+	if (ret < 0) {
+		return ret;
+	}
+
+	if (reply_buffer.status != SCMI_SUCCESS) {
+		return scmi_status_to_errno(reply_buffer.status);
+	}
+
+	*rate = reply_buffer.rate[0];
+
+	return 0;
+}
+
+int scmi_clock_config_set(struct scmi_protocol *proto,
+			  struct scmi_clock_config *cfg)
+{
+	struct scmi_message msg, reply;
+	int status, ret;
+
+	/* sanity checks */
+	if (!proto || !cfg) {
+		return -EINVAL;
+	}
+
+	if (proto->id != SCMI_PROTOCOL_CLOCK) {
+		return -EINVAL;
+	}
+
+	/* extended attributes currently not supported */
+	if (cfg->attributes & SCMI_CLK_CONFIG_EA_MASK) {
+		return -ENOTSUP;
+	}
+
+	/* invalid because extended attributes are not supported */
+	if (SCMI_CLK_CONFIG_ENABLE_DISABLE(cfg->attributes) == 3) {
+		return -ENOTSUP;
+	}
+
+	/* this is a reserved value */
+	if (SCMI_CLK_CONFIG_ENABLE_DISABLE(cfg->attributes) == 2) {
+		return -EINVAL;
+	}
+
+	msg.hdr = SCMI_MESSAGE_HDR_MAKE(SCMI_CLK_MSG_CLOCK_CONFIG_SET,
+					SCMI_COMMAND, proto->id, 0x0);
+	msg.len = sizeof(*cfg);
+	msg.content = cfg;
+
+	reply.hdr = msg.hdr;
+	reply.len = sizeof(status);
+	reply.content = &status;
+
+	ret = scmi_send_message(proto, &msg, &reply);
+	if (ret < 0) {
+		return ret;
+	}
+
+	if (status != SCMI_SUCCESS) {
+		return scmi_status_to_errno(status);
+	}
+
+	return 0;
+}
+
+int scmi_clock_protocol_attributes(struct scmi_protocol *proto, uint32_t *attributes)
+{
+	struct scmi_message msg, reply;
+	struct scmi_clock_attributes_reply reply_buffer;
+	int ret;
+
+	/* sanity checks */
+	if (!proto || !attributes) {
+		return -EINVAL;
+	}
+
+	if (proto->id != SCMI_PROTOCOL_CLOCK) {
+		return -EINVAL;
+	}
+
+	msg.hdr = SCMI_MESSAGE_HDR_MAKE(SCMI_CLK_MSG_PROTOCOL_ATTRIBUTES,
+					SCMI_COMMAND, proto->id, 0x0);
+	/* command has no parameters */
+	msg.len = 0x0;
+	msg.content = NULL;
+
+	reply.hdr = msg.hdr;
+	reply.len = sizeof(reply_buffer);
+	reply.content = &reply_buffer;
+
+	ret = scmi_send_message(proto, &msg, &reply);
+	if (ret < 0) {
+		return ret;
+	}
+
+	if (reply_buffer.status != 0) {
+		return scmi_status_to_errno(reply_buffer.status);
+	}
+
+	*attributes = reply_buffer.attributes;
+
+	return 0;
+}

dts/bindings/firmware/arm,scmi-clock.yaml

@@ -0,0 +1,27 @@
+# Copyright 2024 NXP
+# SPDX-License-Identifier: Apache-2.0
+
+description: System Control and Management Interface (SCMI) clock protocol
+
+compatible: "arm,scmi-clock"
+
+include: [base.yaml, clock-controller.yaml]
+
+properties:
+  shmem:
+    type: phandles
+
+  reg:
+    required: true
+    const: [0x14]
+
+  "#clock-cells":
+    required: true
+    const: 1
+    description: |
+      Vendor-specific clock identifier. Needs to match identifier
+      expected by the SCMI platform as this is directly used in SCMI
+      clock management messages.
+
+clock-cells:
+  - name