1 files changed, 306 insertions, 0 deletions
diff --git a/drivers/hwmon/scpi-hwmon.c b/drivers/hwmon/scpi-hwmon.c
new file mode 100644
index 0000000000..a0d2206095
--- /dev/null
+++ b/drivers/hwmon/scpi-hwmon.c
@@ -0,0 +1,306 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * System Control and Power Interface(SCPI) based hwmon sensor driver
+ *
+ * Copyright (C) 2015 ARM Ltd.
+ * Punit Agrawal <punit.agrawal@arm.com>
+ */
+
+#include <linux/hwmon.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/scpi_protocol.h>
+#include <linux/slab.h>
+#include <linux/sysfs.h>
+#include <linux/thermal.h>
+
+struct sensor_data {
+	unsigned int scale;
+	struct scpi_sensor_info info;
+	struct device_attribute dev_attr_input;
+	struct device_attribute dev_attr_label;
+	char input[20];
+	char label[20];
+};
+
+struct scpi_thermal_zone {
+	int sensor_id;
+	struct scpi_sensors *scpi_sensors;
+};
+
+struct scpi_sensors {
+	struct scpi_ops *scpi_ops;
+	struct sensor_data *data;
+	struct list_head thermal_zones;
+	struct attribute **attrs;
+	struct attribute_group group;
+	const struct attribute_group *groups[2];
+};
+
+static const u32 gxbb_scpi_scale[] = {
+	[TEMPERATURE]	= 1,		/* (celsius)		*/
+	[VOLTAGE]	= 1000,		/* (millivolts)		*/
+	[CURRENT]	= 1000,		/* (milliamperes)	*/
+	[POWER]		= 1000000,	/* (microwatts)		*/
+	[ENERGY]	= 1000000,	/* (microjoules)	*/
+};
+
+static const u32 scpi_scale[] = {
+	[TEMPERATURE]	= 1000,		/* (millicelsius)	*/
+	[VOLTAGE]	= 1000,		/* (millivolts)		*/
+	[CURRENT]	= 1000,		/* (milliamperes)	*/
+	[POWER]		= 1000000,	/* (microwatts)		*/
+	[ENERGY]	= 1000000,	/* (microjoules)	*/
+};
+
+static void scpi_scale_reading(u64 *value, struct sensor_data *sensor)
+{
+	if (scpi_scale[sensor->info.class] != sensor->scale) {
+		*value *= scpi_scale[sensor->info.class];
+		do_div(*value, sensor->scale);
+	}
+}
+
+static int scpi_read_temp(struct thermal_zone_device *tz, int *temp)
+{
+	struct scpi_thermal_zone *zone = thermal_zone_device_priv(tz);
+	struct scpi_sensors *scpi_sensors = zone->scpi_sensors;
+	struct scpi_ops *scpi_ops = scpi_sensors->scpi_ops;
+	struct sensor_data *sensor = &scpi_sensors->data[zone->sensor_id];
+	u64 value;
+	int ret;
+
+	ret = scpi_ops->sensor_get_value(sensor->info.sensor_id, &value);
+	if (ret)
+		return ret;
+
+	scpi_scale_reading(&value, sensor);
+
+	*temp = value;
+	return 0;
+}
+
+/* hwmon callback functions */
+static ssize_t
+scpi_show_sensor(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct scpi_sensors *scpi_sensors = dev_get_drvdata(dev);
+	struct scpi_ops *scpi_ops = scpi_sensors->scpi_ops;
+	struct sensor_data *sensor;
+	u64 value;
+	int ret;
+
+	sensor = container_of(attr, struct sensor_data, dev_attr_input);
+
+	ret = scpi_ops->sensor_get_value(sensor->info.sensor_id, &value);
+	if (ret)
+		return ret;
+
+	scpi_scale_reading(&value, sensor);
+
+	/*
+	 * Temperature sensor values are treated as signed values based on
+	 * observation even though that is not explicitly specified, and
+	 * because an unsigned u64 temperature does not really make practical
+	 * sense especially when the temperature is below zero degrees Celsius.
+	 */
+	if (sensor->info.class == TEMPERATURE)
+		return sprintf(buf, "%lld\n", (s64)value);
+
+	return sprintf(buf, "%llu\n", value);
+}
+
+static ssize_t
+scpi_show_label(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct sensor_data *sensor;
+
+	sensor = container_of(attr, struct sensor_data, dev_attr_label);
+
+	return sprintf(buf, "%s\n", sensor->info.name);
+}
+
+static const struct thermal_zone_device_ops scpi_sensor_ops = {
+	.get_temp = scpi_read_temp,
+};
+
+static const struct of_device_id scpi_of_match[] = {
+	{.compatible = "arm,scpi-sensors", .data = &scpi_scale},
+	{.compatible = "amlogic,meson-gxbb-scpi-sensors", .data = &gxbb_scpi_scale},
+	{},
+};
+MODULE_DEVICE_TABLE(of, scpi_of_match);
+
+static int scpi_hwmon_probe(struct platform_device *pdev)
+{
+	u16 nr_sensors, i;
+	const u32 *scale;
+	int num_temp = 0, num_volt = 0, num_current = 0, num_power = 0;
+	int num_energy = 0;
+	struct scpi_ops *scpi_ops;
+	struct device *hwdev, *dev = &pdev->dev;
+	struct scpi_sensors *scpi_sensors;
+	int idx, ret;
+
+	scpi_ops = get_scpi_ops();
+	if (!scpi_ops)
+		return -EPROBE_DEFER;
+
+	ret = scpi_ops->sensor_get_capability(&nr_sensors);
+	if (ret)
+		return ret;
+
+	if (!nr_sensors)
+		return -ENODEV;
+
+	scpi_sensors = devm_kzalloc(dev, sizeof(*scpi_sensors), GFP_KERNEL);
+	if (!scpi_sensors)
+		return -ENOMEM;
+
+	scpi_sensors->data = devm_kcalloc(dev, nr_sensors,
+				   sizeof(*scpi_sensors->data), GFP_KERNEL);
+	if (!scpi_sensors->data)
+		return -ENOMEM;
+
+	scpi_sensors->attrs = devm_kcalloc(dev, (nr_sensors * 2) + 1,
+				   sizeof(*scpi_sensors->attrs), GFP_KERNEL);
+	if (!scpi_sensors->attrs)
+		return -ENOMEM;
+
+	scpi_sensors->scpi_ops = scpi_ops;
+
+	scale = of_device_get_match_data(&pdev->dev);
+	if (!scale) {
+		dev_err(&pdev->dev, "Unable to initialize scpi-hwmon data\n");
+		return -ENODEV;
+	}
+
+	for (i = 0, idx = 0; i < nr_sensors; i++) {
+		struct sensor_data *sensor = &scpi_sensors->data[idx];
+
+		ret = scpi_ops->sensor_get_info(i, &sensor->info);
+		if (ret)
+			return ret;
+
+		switch (sensor->info.class) {
+		case TEMPERATURE:
+			snprintf(sensor->input, sizeof(sensor->input),
+				 "temp%d_input", num_temp + 1);
+			snprintf(sensor->label, sizeof(sensor->input),
+				 "temp%d_label", num_temp + 1);
+			num_temp++;
+			break;
+		case VOLTAGE:
+			snprintf(sensor->input, sizeof(sensor->input),
+				 "in%d_input", num_volt);
+			snprintf(sensor->label, sizeof(sensor->input),
+				 "in%d_label", num_volt);
+			num_volt++;
+			break;
+		case CURRENT:
+			snprintf(sensor->input, sizeof(sensor->input),
+				 "curr%d_input", num_current + 1);
+			snprintf(sensor->label, sizeof(sensor->input),
+				 "curr%d_label", num_current + 1);
+			num_current++;
+			break;
+		case POWER:
+			snprintf(sensor->input, sizeof(sensor->input),
+				 "power%d_input", num_power + 1);
+			snprintf(sensor->label, sizeof(sensor->input),
+				 "power%d_label", num_power + 1);
+			num_power++;
+			break;
+		case ENERGY:
+			snprintf(sensor->input, sizeof(sensor->input),
+				 "energy%d_input", num_energy + 1);
+			snprintf(sensor->label, sizeof(sensor->input),
+				 "energy%d_label", num_energy + 1);
+			num_energy++;
+			break;
+		default:
+			continue;
+		}
+
+		sensor->scale = scale[sensor->info.class];
+
+		sensor->dev_attr_input.attr.mode = 0444;
+		sensor->dev_attr_input.show = scpi_show_sensor;
+		sensor->dev_attr_input.attr.name = sensor->input;
+
+		sensor->dev_attr_label.attr.mode = 0444;
+		sensor->dev_attr_label.show = scpi_show_label;
+		sensor->dev_attr_label.attr.name = sensor->label;
+
+		scpi_sensors->attrs[idx << 1] = &sensor->dev_attr_input.attr;
+		scpi_sensors->attrs[(idx << 1) + 1] = &sensor->dev_attr_label.attr;
+
+		sysfs_attr_init(scpi_sensors->attrs[idx << 1]);
+		sysfs_attr_init(scpi_sensors->attrs[(idx << 1) + 1]);
+		idx++;
+	}
+
+	scpi_sensors->group.attrs = scpi_sensors->attrs;
+	scpi_sensors->groups[0] = &scpi_sensors->group;
+
+	platform_set_drvdata(pdev, scpi_sensors);
+
+	hwdev = devm_hwmon_device_register_with_groups(dev,
+			"scpi_sensors", scpi_sensors, scpi_sensors->groups);
+
+	if (IS_ERR(hwdev))
+		return PTR_ERR(hwdev);
+
+	/*
+	 * Register the temperature sensors with the thermal framework
+	 * to allow their usage in setting up the thermal zones from
+	 * device tree.
+	 *
+	 * NOTE: Not all temperature sensors maybe used for thermal
+	 * control
+	 */
+	INIT_LIST_HEAD(&scpi_sensors->thermal_zones);
+	for (i = 0; i < nr_sensors; i++) {
+		struct sensor_data *sensor = &scpi_sensors->data[i];
+		struct thermal_zone_device *z;
+		struct scpi_thermal_zone *zone;
+
+		if (sensor->info.class != TEMPERATURE)
+			continue;
+
+		zone = devm_kzalloc(dev, sizeof(*zone), GFP_KERNEL);
+		if (!zone)
+			return -ENOMEM;
+
+		zone->sensor_id = i;
+		zone->scpi_sensors = scpi_sensors;
+		z = devm_thermal_of_zone_register(dev,
+						  sensor->info.sensor_id,
+						  zone,
+						  &scpi_sensor_ops);
+		/*
+		 * The call to thermal_zone_of_sensor_register returns
+		 * an error for sensors that are not associated with
+		 * any thermal zones or if the thermal subsystem is
+		 * not configured.
+		 */
+		if (IS_ERR(z))
+			devm_kfree(dev, zone);
+	}
+
+	return 0;
+}
+
+static struct platform_driver scpi_hwmon_platdrv = {
+	.driver = {
+		.name	= "scpi-hwmon",
+		.of_match_table = scpi_of_match,
+	},
+	.probe		= scpi_hwmon_probe,
+};
+module_platform_driver(scpi_hwmon_platdrv);
+
+MODULE_AUTHOR("Punit Agrawal <punit.agrawal@arm.com>");
+MODULE_DESCRIPTION("ARM SCPI HWMON interface driver");
+MODULE_LICENSE("GPL v2");