firmware: arm_scmi: add initial support for sensor protocol

The sensor protocol provides functions to manage platform sensors, and
provides the commands to describe the protocol version and the various
attribute flags. It also provides commands to discover various sensors
implemented and managed by the platform, read any sensor synchronously
or asynchronously as allowed by the platform, program sensor attributes
and/or configurations, if applicable.

This patch adds support for most of the above features.

Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

drivers/firmware/arm_scmi/Makefile

 obj-y	= scmi-bus.o scmi-driver.o scmi-protocols.o
 scmi-bus-y = bus.o
 scmi-driver-y = driver.o
-scmi-protocols-y = base.o clock.o perf.o power.o
+scmi-protocols-y = base.o clock.o perf.o power.o sensors.o

drivers/firmware/arm_scmi/sensors.c

+// SPDX-License-Identifier: GPL-2.0
+/*
+ * System Control and Management Interface (SCMI) Sensor Protocol
+ *
+ * Copyright (C) 2018 ARM Ltd.
+ */
+
+#include "common.h"
+
+enum scmi_sensor_protocol_cmd {
+	SENSOR_DESCRIPTION_GET = 0x3,
+	SENSOR_CONFIG_SET = 0x4,
+	SENSOR_TRIP_POINT_SET = 0x5,
+	SENSOR_READING_GET = 0x6,
+};
+
+struct scmi_msg_resp_sensor_attributes {
+	__le16 num_sensors;
+	u8 max_requests;
+	u8 reserved;
+	__le32 reg_addr_low;
+	__le32 reg_addr_high;
+	__le32 reg_size;
+};
+
+struct scmi_msg_resp_sensor_description {
+	__le16 num_returned;
+	__le16 num_remaining;
+	struct {
+		__le32 id;
+		__le32 attributes_low;
+#define SUPPORTS_ASYNC_READ(x)	((x) & BIT(31))
+#define NUM_TRIP_POINTS(x)	(((x) >> 4) & 0xff)
+		__le32 attributes_high;
+#define SENSOR_TYPE(x)		((x) & 0xff)
+#define SENSOR_SCALE(x)		(((x) >> 11) & 0x3f)
+#define SENSOR_UPDATE_SCALE(x)	(((x) >> 22) & 0x1f)
+#define SENSOR_UPDATE_BASE(x)	(((x) >> 27) & 0x1f)
+		    u8 name[SCMI_MAX_STR_SIZE];
+	} desc[0];
+};
+
+struct scmi_msg_set_sensor_config {
+	__le32 id;
+	__le32 event_control;
+};
+
+struct scmi_msg_set_sensor_trip_point {
+	__le32 id;
+	__le32 event_control;
+#define SENSOR_TP_EVENT_MASK	(0x3)
+#define SENSOR_TP_DISABLED	0x0
+#define SENSOR_TP_POSITIVE	0x1
+#define SENSOR_TP_NEGATIVE	0x2
+#define SENSOR_TP_BOTH		0x3
+#define SENSOR_TP_ID(x)		(((x) & 0xff) << 4)
+	__le32 value_low;
+	__le32 value_high;
+};
+
+struct scmi_msg_sensor_reading_get {
+	__le32 id;
+	__le32 flags;
+#define SENSOR_READ_ASYNC	BIT(0)
+};
+
+struct sensors_info {
+	int num_sensors;
+	int max_requests;
+	u64 reg_addr;
+	u32 reg_size;
+	struct scmi_sensor_info *sensors;
+};
+
+static int scmi_sensor_attributes_get(const struct scmi_handle *handle,
+				      struct sensors_info *si)
+{
+	int ret;
+	struct scmi_xfer *t;
+	struct scmi_msg_resp_sensor_attributes *attr;
+
+	ret = scmi_one_xfer_init(handle, PROTOCOL_ATTRIBUTES,
+				 SCMI_PROTOCOL_SENSOR, 0, sizeof(*attr), &t);
+	if (ret)
+		return ret;
+
+	attr = t->rx.buf;
+
+	ret = scmi_do_xfer(handle, t);
+	if (!ret) {
+		si->num_sensors = le16_to_cpu(attr->num_sensors);
+		si->max_requests = attr->max_requests;
+		si->reg_addr = le32_to_cpu(attr->reg_addr_low) |
+				(u64)le32_to_cpu(attr->reg_addr_high) << 32;
+		si->reg_size = le32_to_cpu(attr->reg_size);
+	}
+
+	scmi_one_xfer_put(handle, t);
+	return ret;
+}
+
+static int scmi_sensor_description_get(const struct scmi_handle *handle,
+				       struct sensors_info *si)
+{
+	int ret, cnt;
+	u32 desc_index = 0;
+	u16 num_returned, num_remaining;
+	struct scmi_xfer *t;
+	struct scmi_msg_resp_sensor_description *buf;
+
+	ret = scmi_one_xfer_init(handle, SENSOR_DESCRIPTION_GET,
+				 SCMI_PROTOCOL_SENSOR, sizeof(__le32), 0, &t);
+	if (ret)
+		return ret;
+
+	buf = t->rx.buf;
+
+	do {
+		/* Set the number of sensors to be skipped/already read */
+		*(__le32 *)t->tx.buf = cpu_to_le32(desc_index);
+
+		ret = scmi_do_xfer(handle, t);
+		if (ret)
+			break;
+
+		num_returned = le16_to_cpu(buf->num_returned);
+		num_remaining = le16_to_cpu(buf->num_remaining);
+
+		if (desc_index + num_returned > si->num_sensors) {
+			dev_err(handle->dev, "No. of sensors can't exceed %d",
+				si->num_sensors);
+			break;
+		}
+
+		for (cnt = 0; cnt < num_returned; cnt++) {
+			u32 attrh;
+			struct scmi_sensor_info *s;
+
+			attrh = le32_to_cpu(buf->desc[cnt].attributes_high);
+			s = &si->sensors[desc_index + cnt];
+			s->id = le32_to_cpu(buf->desc[cnt].id);
+			s->type = SENSOR_TYPE(attrh);
+			memcpy(s->name, buf->desc[cnt].name, SCMI_MAX_STR_SIZE);
+		}
+
+		desc_index += num_returned;
+		/*
+		 * check for both returned and remaining to avoid infinite
+		 * loop due to buggy firmware
+		 */
+	} while (num_returned && num_remaining);
+
+	scmi_one_xfer_put(handle, t);
+	return ret;
+}
+
+static int
+scmi_sensor_configuration_set(const struct scmi_handle *handle, u32 sensor_id)
+{
+	int ret;
+	u32 evt_cntl = BIT(0);
+	struct scmi_xfer *t;
+	struct scmi_msg_set_sensor_config *cfg;
+
+	ret = scmi_one_xfer_init(handle, SENSOR_CONFIG_SET,
+				 SCMI_PROTOCOL_SENSOR, sizeof(*cfg), 0, &t);
+	if (ret)
+		return ret;
+
+	cfg = t->tx.buf;
+	cfg->id = cpu_to_le32(sensor_id);
+	cfg->event_control = cpu_to_le32(evt_cntl);
+
+	ret = scmi_do_xfer(handle, t);
+
+	scmi_one_xfer_put(handle, t);
+	return ret;
+}
+
+static int scmi_sensor_trip_point_set(const struct scmi_handle *handle,
+				      u32 sensor_id, u8 trip_id, u64 trip_value)
+{
+	int ret;
+	u32 evt_cntl = SENSOR_TP_BOTH;
+	struct scmi_xfer *t;
+	struct scmi_msg_set_sensor_trip_point *trip;
+
+	ret = scmi_one_xfer_init(handle, SENSOR_TRIP_POINT_SET,
+				 SCMI_PROTOCOL_SENSOR, sizeof(*trip), 0, &t);
+	if (ret)
+		return ret;
+
+	trip = t->tx.buf;
+	trip->id = cpu_to_le32(sensor_id);
+	trip->event_control = cpu_to_le32(evt_cntl | SENSOR_TP_ID(trip_id));
+	trip->value_low = cpu_to_le32(trip_value & 0xffffffff);
+	trip->value_high = cpu_to_le32(trip_value >> 32);
+
+	ret = scmi_do_xfer(handle, t);
+
+	scmi_one_xfer_put(handle, t);
+	return ret;
+}
+
+static int scmi_sensor_reading_get(const struct scmi_handle *handle,
+				   u32 sensor_id, bool async, u64 *value)
+{
+	int ret;
+	struct scmi_xfer *t;
+	struct scmi_msg_sensor_reading_get *sensor;
+
+	ret = scmi_one_xfer_init(handle, SENSOR_READING_GET,
+				 SCMI_PROTOCOL_SENSOR, sizeof(*sensor),
+				 sizeof(u64), &t);
+	if (ret)
+		return ret;
+
+	sensor = t->tx.buf;
+	sensor->id = cpu_to_le32(sensor_id);
+	sensor->flags = cpu_to_le32(async ? SENSOR_READ_ASYNC : 0);
+
+	ret = scmi_do_xfer(handle, t);
+	if (!ret) {
+		__le32 *pval = t->rx.buf;
+
+		*value = le32_to_cpu(*pval);
+		*value |= (u64)le32_to_cpu(*(pval + 1)) << 32;
+	}
+
+	scmi_one_xfer_put(handle, t);
+	return ret;
+}
+
+static const struct scmi_sensor_info *
+scmi_sensor_info_get(const struct scmi_handle *handle, u32 sensor_id)
+{
+	struct sensors_info *si = handle->sensor_priv;
+
+	return si->sensors + sensor_id;
+}
+
+static int scmi_sensor_count_get(const struct scmi_handle *handle)
+{
+	struct sensors_info *si = handle->sensor_priv;
+
+	return si->num_sensors;
+}
+
+static struct scmi_sensor_ops sensor_ops = {
+	.count_get = scmi_sensor_count_get,
+	.info_get = scmi_sensor_info_get,
+	.configuration_set = scmi_sensor_configuration_set,
+	.trip_point_set = scmi_sensor_trip_point_set,
+	.reading_get = scmi_sensor_reading_get,
+};
+
+static int scmi_sensors_protocol_init(struct scmi_handle *handle)
+{
+	u32 version;
+	struct sensors_info *sinfo;
+
+	scmi_version_get(handle, SCMI_PROTOCOL_SENSOR, &version);
+
+	dev_dbg(handle->dev, "Sensor Version %d.%d\n",
+		PROTOCOL_REV_MAJOR(version), PROTOCOL_REV_MINOR(version));
+
+	sinfo = devm_kzalloc(handle->dev, sizeof(*sinfo), GFP_KERNEL);
+	if (!sinfo)
+		return -ENOMEM;
+
+	scmi_sensor_attributes_get(handle, sinfo);
+
+	sinfo->sensors = devm_kcalloc(handle->dev, sinfo->num_sensors,
+				      sizeof(*sinfo->sensors), GFP_KERNEL);
+	if (!sinfo->sensors)
+		return -ENOMEM;
+
+	scmi_sensor_description_get(handle, sinfo);
+
+	handle->sensor_ops = &sensor_ops;
+	handle->sensor_priv = sinfo;
+
+	return 0;
+}
+
+static int __init scmi_sensors_init(void)
+{
+	return scmi_protocol_register(SCMI_PROTOCOL_SENSOR,
+				      &scmi_sensors_protocol_init);
+}
+subsys_initcall(scmi_sensors_init);

include/linux/scmi_protocol.h

@@ -137,6 +137,49 @@ struct scmi_power_ops {
 			 u32 *state);
 };
 
+struct scmi_sensor_info {
+	u32 id;
+	u8 type;
+	char name[SCMI_MAX_STR_SIZE];
+};
+
+/*
+ * Partial list from Distributed Management Task Force (DMTF) specification:
+ * DSP0249 (Platform Level Data Model specification)
+ */
+enum scmi_sensor_class {
+	NONE = 0x0,
+	TEMPERATURE_C = 0x2,
+	VOLTAGE = 0x5,
+	CURRENT = 0x6,
+	POWER = 0x7,
+	ENERGY = 0x8,
+};
+
+/**
+ * struct scmi_sensor_ops - represents the various operations provided
+ *	by SCMI Sensor Protocol
+ *
+ * @count_get: get the count of sensors provided by SCMI
+ * @info_get: get the information of the specified sensor
+ * @configuration_set: control notifications on cross-over events for
+ *	the trip-points
+ * @trip_point_set: selects and configures a trip-point of interest
+ * @reading_get: gets the current value of the sensor
+ */
+struct scmi_sensor_ops {
+	int (*count_get)(const struct scmi_handle *handle);
+
+	const struct scmi_sensor_info *(*info_get)
+		(const struct scmi_handle *handle, u32 sensor_id);
+	int (*configuration_set)(const struct scmi_handle *handle,
+				 u32 sensor_id);
+	int (*trip_point_set)(const struct scmi_handle *handle, u32 sensor_id,
+			      u8 trip_id, u64 trip_value);
+	int (*reading_get)(const struct scmi_handle *handle, u32 sensor_id,
+			   bool async, u64 *value);
+};
+
 /**
  * struct scmi_handle - Handle returned to ARM SCMI clients for usage.
  *
@@ -145,6 +188,7 @@ struct scmi_power_ops {
  * @power_ops: pointer to set of power protocol operations
  * @perf_ops: pointer to set of performance protocol operations
  * @clk_ops: pointer to set of clock protocol operations
+ * @sensor_ops: pointer to set of sensor protocol operations
  */
 struct scmi_handle {
 	struct device *dev;
@@ -152,10 +196,12 @@ struct scmi_handle {
 	struct scmi_perf_ops *perf_ops;
 	struct scmi_clk_ops *clk_ops;
 	struct scmi_power_ops *power_ops;
+	struct scmi_sensor_ops *sensor_ops;
 	/* for protocol internal use */
 	void *perf_priv;
 	void *clk_priv;
 	void *power_priv;
+	void *sensor_priv;
 };
 
 enum scmi_std_protocol {