On Tue, May 30, 2017 at 11:05:07AM +0200, Carlo Caione wrote:
> From: Carlo Caione <carlo@xxxxxxxxxxxx>
>
> The implementation details for SCPI seems to suggest that the sensor
> readings must be reported by SCP using a well defined scale
> (millidegree Celsius for temperature, millivolts for voltage,
> milliamperes for current, microwatts for power and microjoules for
> energy).
>
> This is also important for the interaction with other subsystems: for
> example both the thermal sub-system and the hwmon sysfs interface expect
> the temperature expressed in millidegree Celsius.
>
> Unfortunately since this behaviour is dependent on the firmware
> implementation there are cases where the sensor readings are reported
> using a different scale. For example in the Amlogic SoCs the
> temperature is reported in degree and not millidegree Celsius.
>
> To take into account this discrepancy and fixup the values reported by
> SCP a new compatible 'amlogic,meson-gxbb-scpi-sensors' is introduced and
> used in this patch by the scpi-hwmon driver to convert the sensor
> readings to the expected scale.
>
> Signed-off-by: Carlo Caione <carlo@xxxxxxxxxxxx>
> Acked-by: Sudeep Holla <sudeep.holla@xxxxxxx>
Applied to hwmon-next. If the dt property needs to be updated, we can do
that later.
Thanks,
Guenter
> ---
> drivers/hwmon/scpi-hwmon.c | 54 ++++++++++++++++++++++++++++++++++++++++------
> 1 file changed, 48 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/hwmon/scpi-hwmon.c b/drivers/hwmon/scpi-hwmon.c
> index 094f948..a586480 100644
> --- a/drivers/hwmon/scpi-hwmon.c
> +++ b/drivers/hwmon/scpi-hwmon.c
> @@ -16,6 +16,7 @@
>
> #include <linux/hwmon.h>
> #include <linux/module.h>
> +#include <linux/of_device.h>
> #include <linux/platform_device.h>
> #include <linux/scpi_protocol.h>
> #include <linux/slab.h>
> @@ -23,6 +24,7 @@
> #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;
> @@ -44,6 +46,30 @@ struct scpi_sensors {
> 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(void *dev, int *temp)
> {
> struct scpi_thermal_zone *zone = dev;
> @@ -57,6 +83,8 @@ static int scpi_read_temp(void *dev, int *temp)
> if (ret)
> return ret;
>
> + scpi_scale_reading(&value, sensor);
> +
> *temp = value;
> return 0;
> }
> @@ -77,6 +105,8 @@ scpi_show_sensor(struct device *dev, struct device_attribute *attr, char *buf)
> if (ret)
> return ret;
>
> + scpi_scale_reading(&value, sensor);
> +
> return sprintf(buf, "%llu\n", value);
> }
>
> @@ -94,14 +124,23 @@ static struct thermal_zone_of_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;
> + const struct of_device_id *of_id;
> int idx, ret;
>
> scpi_ops = get_scpi_ops();
> @@ -131,6 +170,13 @@ static int scpi_hwmon_probe(struct platform_device *pdev)
>
> scpi_sensors->scpi_ops = scpi_ops;
>
> + of_id = of_match_device(scpi_of_match, &pdev->dev);
> + if (!of_id) {
> + dev_err(&pdev->dev, "Unable to initialize scpi-hwmon data\n");
> + return -ENODEV;
> + }
> + scale = of_id->data;
> +
> for (i = 0, idx = 0; i < nr_sensors; i++) {
> struct sensor_data *sensor = &scpi_sensors->data[idx];
>
> @@ -178,6 +224,8 @@ static int scpi_hwmon_probe(struct platform_device *pdev)
> continue;
> }
>
> + sensor->scale = scale[sensor->info.class];
> +
> sensor->dev_attr_input.attr.mode = S_IRUGO;
> sensor->dev_attr_input.show = scpi_show_sensor;
> sensor->dev_attr_input.attr.name = sensor->input;
> @@ -247,12 +295,6 @@ static int scpi_hwmon_probe(struct platform_device *pdev)
> return 0;
> }
>
> -static const struct of_device_id scpi_of_match[] = {
> - {.compatible = "arm,scpi-sensors"},
> - {},
> -};
> -MODULE_DEVICE_TABLE(of, scpi_of_match);
> -
> static struct platform_driver scpi_hwmon_platdrv = {
> .driver = {
> .name = "scpi-hwmon",
--
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