Re: [PATCH v2 16/18] hwmon: add support for sensors exported via ARM SCMI

[Guenter Roeck <linux@roeck-us.net>]

On Fri, Aug 04, 2017 at 03:31:42PM +0100, Sudeep Holla wrote:
> Create a driver to add support for SoC sensors exported by the System
> Control Processor (SCP) via the System Control and Management Interface
> (SCMI). The supported sensor types is one of voltage, temperature,
> current, and power.
> 
> The sensor labels and values provided by the SCP are exported via the
> hwmon sysfs interface.
> 
> Cc: Guenter Roeck <linux@roeck-us.net>
> Cc: linux-hwmon@vger.kernel.org
> Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
> ---
>  drivers/hwmon/Kconfig      |  12 +++
>  drivers/hwmon/Makefile     |   1 +
>  drivers/hwmon/scmi-hwmon.c | 261 +++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 274 insertions(+)
>  create mode 100644 drivers/hwmon/scmi-hwmon.c
> 
> diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
> index 5ef2814345ef..2bb63af8d674 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 d4641a9f16c1..02c3783c319f 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..f38c9708d99c
> --- /dev/null
> +++ b/drivers/hwmon/scmi-hwmon.c
> @@ -0,0 +1,261 @@
> +/*
> + * System Control and Management Interface(SCMI) based hwmon sensor driver
> + *
> + * Copyright (C) 2017 ARM Ltd.
> + * Punit Agrawal <punit.agrawal@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 sensor_data {
> +	const struct scmi_sensor_info *info;
> +	struct device_attribute dev_attr_input;
> +	struct device_attribute dev_attr_label;
> +	char input[20];
> +	char label[20];
> +};
> +
> +struct scmi_thermal_zone {
> +	int sensor_id;
> +	struct scmi_sensors *scmi_sensors;
> +};
> +
> +struct scmi_sensors {
> +	const struct scmi_handle *handle;
> +	struct sensor_data *data;
> +	struct list_head thermal_zones;
> +	struct attribute **attrs;
> +	struct attribute_group group;
> +	const struct attribute_group *groups[2];
> +};
> +
> +static int scmi_read_temp(void *dev, int *temp)
> +{
> +	struct scmi_thermal_zone *zone = dev;
> +	struct scmi_sensors *scmi_sensors = zone->scmi_sensors;
> +	const struct scmi_handle *handle = scmi_sensors->handle;
> +	struct sensor_data *sensor = &scmi_sensors->data[zone->sensor_id];
> +	u64 value;
> +	int ret;
> +
> +	ret = handle->sensor_ops->reading_get(handle, sensor->info->id,
> +					      false, &value);
> +	if (ret)
> +		return ret;
> +
> +	*temp = value;
> +	return 0;
> +}
> +
> +/* hwmon callback functions */
> +static ssize_t
> +scmi_show_sensor(struct device *dev, struct device_attribute *attr, char *buf)
> +{
> +	struct scmi_sensors *scmi_sensors = dev_get_drvdata(dev);
> +	const struct scmi_handle *handle = scmi_sensors->handle;
> +	struct sensor_data *sensor;
> +	u64 value;
> +	int ret;
> +
> +	sensor = container_of(attr, struct sensor_data, dev_attr_input);
> +
> +	ret = handle->sensor_ops->reading_get(handle, sensor->info->id,
> +					      false, &value);
> +	if (ret)
> +		return ret;
> +
> +	return sprintf(buf, "%llu\n", value);
> +}
> +
> +static ssize_t
> +scmi_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 struct thermal_zone_of_device_ops scmi_sensor_ops = {
> +	.get_temp = scmi_read_temp,
> +};
> +
> +static int scmi_hwmon_probe(struct platform_device *pdev)
> +{
> +	int idx;
> +	u16 nr_sensors, i;
> +	int num_temp = 0, num_volt = 0, num_current = 0, num_power = 0;
> +	int num_energy = 0;
> +	struct device *hwdev, *dev = &pdev->dev;
> +	struct scmi_sensors *scmi_sensors;
> +	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->data = devm_kcalloc(dev, nr_sensors,
> +					  sizeof(*scmi_sensors->data),
> +					  GFP_KERNEL);
> +	if (!scmi_sensors->data)
> +		return -ENOMEM;
> +
> +	scmi_sensors->attrs = devm_kcalloc(dev, (nr_sensors * 2) + 1,
> +					   sizeof(*scmi_sensors->attrs),
> +					   GFP_KERNEL);
> +	if (!scmi_sensors->attrs)
> +		return -ENOMEM;
> +
> +	scmi_sensors->handle = handle;
> +
> +	for (i = 0, idx = 0; i < nr_sensors; i++) {
> +		struct sensor_data *sensor = &scmi_sensors->data[idx];
> +
> +		sensor->info = handle->sensor_ops->info_get(handle, i);
> +		if (!sensor->info)
> +			return PTR_ERR(sensor->info);
> +
> +		switch (sensor->info->type) {
> +		case TEMPERATURE_C:
> +			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->dev_attr_input.attr.mode = S_IRUGO;
> +		sensor->dev_attr_input.show = scmi_show_sensor;
> +		sensor->dev_attr_input.attr.name = sensor->input;
> +
> +		sensor->dev_attr_label.attr.mode = S_IRUGO;
> +		sensor->dev_attr_label.show = scmi_show_label;
> +		sensor->dev_attr_label.attr.name = sensor->label;
> +
> +		scmi_sensors->attrs[idx << 1] = &sensor->dev_attr_input.attr;
> +		scmi_sensors->attrs[(idx << 1) + 1] =
> +					&sensor->dev_attr_label.attr;
> +
> +		sysfs_attr_init(scmi_sensors->attrs[idx << 1]);
> +		sysfs_attr_init(scmi_sensors->attrs[(idx << 1) + 1]);
> +		idx++;
> +	}
> +
> +	scmi_sensors->group.attrs = scmi_sensors->attrs;
> +	scmi_sensors->groups[0] = &scmi_sensors->group;
> +
> +	platform_set_drvdata(pdev, scmi_sensors);
> +
> +	hwdev = devm_hwmon_device_register_with_groups(dev, "scmi_sensors",
> +						       scmi_sensors,
> +						       scmi_sensors->groups);

Can you rework this to use devm_hwmon_device_register_with_info(),
and if possible let it handle the thermal registration ? 

Thanks,
Guenter

> +
> +	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(&scmi_sensors->thermal_zones);
> +	for (i = 0; i < nr_sensors; i++) {
> +		struct sensor_data *sensor = &scmi_sensors->data[i];
> +		const struct scmi_sensor_info *info = sensor->info;
> +		struct thermal_zone_device *z;
> +		struct scmi_thermal_zone *zone;
> +
> +		if (info->type != TEMPERATURE_C)
> +			continue;
> +
> +		zone = devm_kzalloc(dev, sizeof(*zone), GFP_KERNEL);
> +		if (!zone)
> +			return -ENOMEM;
> +
> +		zone->sensor_id = i;
> +		zone->scmi_sensors = scmi_sensors;
> +		z = devm_thermal_zone_of_sensor_register(dev, info->id, zone,
> +							 &scmi_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);
> +			continue;
> +		}
> +	}
> +
> +	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("Punit Agrawal <punit.agrawal@arm.com>");
> +MODULE_DESCRIPTION("ARM SCMI HWMON interface driver");
> +MODULE_LICENSE("GPL v2");
> -- 
> 2.7.4
>