[v3,20/22] hwmon: add support for sensors exported via ARM SCMI

diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index d65431417b17..0b75e9a89463 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -321,6 +321,18 @@  config SENSORS_APPLESMC
 	  Say Y here if you have an applicable laptop and want to experience
 	  the awesome power of applesmc.
 
+config SENSORS_ARM_SCMI
+	tristate "ARM SCMI Sensors"
+	depends on ARM_SCMI_PROTOCOL
+	depends on THERMAL || !THERMAL_OF
+	help
+	  This driver provides support for temperature, voltage, current
+	  and power sensors available on SCMI based platforms. The actual
+	  number and type of sensors exported depend on the platform.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called scmi-hwmon.
+
 config SENSORS_ARM_SCPI
 	tristate "ARM SCPI Sensors"
 	depends on ARM_SCPI_PROTOCOL
diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
index c84d9784be98..a51c2dcef11c 100644
--- a/drivers/hwmon/Makefile
+++ b/drivers/hwmon/Makefile
@@ -44,6 +44,7 @@  obj-$(CONFIG_SENSORS_ADT7462)	+= adt7462.o
 obj-$(CONFIG_SENSORS_ADT7470)	+= adt7470.o
 obj-$(CONFIG_SENSORS_ADT7475)	+= adt7475.o
 obj-$(CONFIG_SENSORS_APPLESMC)	+= applesmc.o
+obj-$(CONFIG_SENSORS_ARM_SCMI)	+= scmi-hwmon.o
 obj-$(CONFIG_SENSORS_ARM_SCPI)	+= scpi-hwmon.o
 obj-$(CONFIG_SENSORS_ASC7621)	+= asc7621.o
 obj-$(CONFIG_SENSORS_ASPEED)	+= aspeed-pwm-tacho.o
diff --git a/drivers/hwmon/scmi-hwmon.c b/drivers/hwmon/scmi-hwmon.c
new file mode 100644
index 000000000000..0a8c0e8dc5d1
--- /dev/null
+++ b/drivers/hwmon/scmi-hwmon.c
@@ -0,0 +1,235 @@ 
+/*
+ * System Control and Management Interface(SCMI) based hwmon sensor driver
+ *
+ * Copyright (C) 2017 ARM Ltd.
+ * Sudeep Holla <sudeep.holla@arm.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed "as is" WITHOUT ANY WARRANTY of any
+ * kind, whether express or implied; without even the implied warranty
+ * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/hwmon.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/scmi_protocol.h>
+#include <linux/slab.h>
+#include <linux/sysfs.h>
+#include <linux/thermal.h>
+
+struct scmi_sensors {
+	const struct scmi_handle *handle;
+	const struct scmi_sensor_info **info[hwmon_max];
+};
+
+static int scmi_hwmon_read(struct device *dev, enum hwmon_sensor_types type,
+			   u32 attr, int channel, long *val)
+{
+	int ret;
+	u64 value;
+	const struct scmi_sensor_info *sensor;
+	struct scmi_sensors *scmi_sensors = dev_get_drvdata(dev);
+	const struct scmi_handle *h = scmi_sensors->handle;
+
+	sensor = *(scmi_sensors->info[type] + channel);
+	ret = h->sensor_ops->reading_get(h, sensor->id, false, &value);
+	if (!ret)
+		*val = value;
+
+	return ret;
+}
+
+static int
+scmi_hwmon_read_string(struct device *dev, enum hwmon_sensor_types type,
+		       u32 attr, int channel, const char **str)
+{
+	const struct scmi_sensor_info *sensor;
+	struct scmi_sensors *scmi_sensors = dev_get_drvdata(dev);
+
+	sensor = *(scmi_sensors->info[type] + channel);
+	*str = sensor->name;
+
+	return 0;
+}
+
+static umode_t
+scmi_hwmon_is_visible(const void *drvdata, enum hwmon_sensor_types type,
+		      u32 attr, int channel)
+{
+	const struct scmi_sensor_info *sensor;
+	const struct scmi_sensors *scmi_sensors = drvdata;
+
+	sensor = *(scmi_sensors->info[type] + channel);
+	if (sensor && sensor->name)
+		return S_IRUGO;
+
+	return 0;
+}
+
+static const struct hwmon_ops scmi_hwmon_ops = {
+	.is_visible = scmi_hwmon_is_visible,
+	.read = scmi_hwmon_read,
+	.read_string = scmi_hwmon_read_string,
+};
+
+static struct hwmon_chip_info scmi_chip_info = {
+	.ops = &scmi_hwmon_ops,
+	.info = NULL,
+};
+
+static int scmi_hwmon_add_chan_info(struct hwmon_channel_info *scmi_hwmon_chan,
+				    struct device *dev, int num,
+				    enum hwmon_sensor_types type, u32 config)
+{
+	int i;
+	u32 *cfg = devm_kcalloc(dev, num + 1, sizeof(*cfg), GFP_KERNEL);
+
+	if (!cfg)
+		return -ENOMEM;
+
+	scmi_hwmon_chan->type = type;
+	scmi_hwmon_chan->config = cfg;
+	for (i = 0; i < num; i++, cfg++)
+		*cfg = config;
+
+	return 0;
+}
+
+static enum hwmon_sensor_types scmi_types[] = {
+	[TEMPERATURE_C] = hwmon_temp,
+	[VOLTAGE] = hwmon_in,
+	[CURRENT] = hwmon_curr,
+	[POWER] = hwmon_power,
+	[ENERGY] = hwmon_energy,
+};
+
+static u32 hwmon_attributes[] = {
+	[hwmon_chip] = HWMON_C_REGISTER_TZ,
+	[hwmon_temp] = HWMON_T_INPUT | HWMON_T_LABEL,
+	[hwmon_in] = HWMON_I_INPUT | HWMON_I_LABEL,
+	[hwmon_curr] = HWMON_C_INPUT | HWMON_C_LABEL,
+	[hwmon_power] = HWMON_P_INPUT | HWMON_P_LABEL,
+	[hwmon_energy] = HWMON_E_INPUT | HWMON_E_LABEL,
+};
+
+static int scmi_hwmon_probe(struct platform_device *pdev)
+{
+	int i, idx;
+	u16 nr_sensors;
+	enum hwmon_sensor_types type;
+	struct scmi_sensors *scmi_sensors;
+	const struct scmi_sensor_info *sensor;
+	int nr_count[hwmon_max] = {0}, nr_types = 0;
+	const struct hwmon_chip_info *chip_info;
+	struct device *hwdev, *dev = &pdev->dev;
+	struct hwmon_channel_info *scmi_hwmon_chan;
+	const struct hwmon_channel_info **ptr_scmi_ci;
+	const struct scmi_handle *handle = devm_scmi_handle_get(dev);
+
+	if (IS_ERR_OR_NULL(handle) || !handle->sensor_ops)
+		return -EPROBE_DEFER;
+
+	nr_sensors = handle->sensor_ops->count_get(handle);
+	if (!nr_sensors)
+		return -EIO;
+
+	scmi_sensors = devm_kzalloc(dev, sizeof(*scmi_sensors), GFP_KERNEL);
+	if (!scmi_sensors)
+		return -ENOMEM;
+
+	scmi_sensors->handle = handle;
+
+	for (i = 0; i < nr_sensors; i++) {
+		sensor = handle->sensor_ops->info_get(handle, i);
+		if (!sensor)
+			return PTR_ERR(sensor);
+
+		switch (sensor->type) {
+		case TEMPERATURE_C:
+		case VOLTAGE:
+		case CURRENT:
+		case POWER:
+		case ENERGY:
+			type = scmi_types[sensor->type];
+			if (!nr_count[type])
+				nr_types++;
+			nr_count[type]++;
+			break;
+		}
+	}
+
+	if (nr_count[hwmon_temp])
+		nr_count[hwmon_chip]++, nr_types++;
+
+	scmi_hwmon_chan = devm_kcalloc(dev, nr_types, sizeof(*scmi_hwmon_chan),
+				       GFP_KERNEL);
+	if (!scmi_hwmon_chan)
+		return -ENOMEM;
+
+	ptr_scmi_ci = devm_kcalloc(dev, nr_types + 1, sizeof(*ptr_scmi_ci),
+				   GFP_KERNEL);
+	if (!ptr_scmi_ci)
+		return -ENOMEM;
+
+	scmi_chip_info.info = ptr_scmi_ci;
+	chip_info = &scmi_chip_info;
+
+	for (type = 0; type < hwmon_max && nr_count[type]; type++) {
+		scmi_hwmon_add_chan_info(scmi_hwmon_chan, dev, nr_count[type],
+					 type, hwmon_attributes[type]);
+		*ptr_scmi_ci++ = scmi_hwmon_chan++;
+
+		scmi_sensors->info[type] =
+			devm_kcalloc(dev, nr_count[type],
+				     sizeof(*scmi_sensors->info), GFP_KERNEL);
+		if (!scmi_sensors->info[type])
+			return -ENOMEM;
+	}
+
+	*ptr_scmi_ci = NULL;
+	platform_set_drvdata(pdev, scmi_sensors);
+
+	for (i = nr_sensors - 1; i >= 0 ; i--) {
+		sensor = handle->sensor_ops->info_get(handle, i);
+		if (!sensor)
+			continue;
+
+		switch (sensor->type) {
+		case TEMPERATURE_C:
+		case VOLTAGE:
+		case CURRENT:
+		case POWER:
+		case ENERGY:
+			type = scmi_types[sensor->type];
+			idx = --nr_count[type];
+			*(scmi_sensors->info[type] + idx) = sensor;
+			break;
+		}
+	}
+
+	hwdev = devm_hwmon_device_register_with_info(dev, "scmi_sensors",
+						     scmi_sensors, chip_info,
+						     NULL);
+
+	if (IS_ERR(hwdev))
+		return PTR_ERR(hwdev);
+
+	return 0;
+}
+
+static struct platform_driver scmi_hwmon_platdrv = {
+	.driver = {
+		.name	= "scmi-hwmon",
+	},
+	.probe		= scmi_hwmon_probe,
+};
+module_platform_driver(scmi_hwmon_platdrv);
+
+MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
+MODULE_DESCRIPTION("ARM SCMI HWMON interface driver");
+MODULE_LICENSE("GPL v2");