Re: [PATCH 2/3] hwmon: surface_temp: Add support for sensor names

[Hans de Goede]

Hi,

On 3/30/24 12:24 PM, Maximilian Luz wrote:
> From: Ivor Wanders <ivor@xxxxxxxxxxxx>
> 
> The thermal subsystem of the Surface Aggregator Module allows us to
> query the names of the respective thermal sensors. Forward those to
> userspace.
> 
> Signed-off-by: Ivor Wanders <ivor@xxxxxxxxxxxx>
> Co-developed-by: Maximilian Luz <luzmaximilian@xxxxxxxxx>
> Signed-off-by: Maximilian Luz <luzmaximilian@xxxxxxxxx>

Thanks, patch looks good to me:

Reviewed-by: Hans de Goede <hdegoede@xxxxxxxxxx>

Regards,

Hans



> ---
>  drivers/hwmon/surface_temp.c | 112 +++++++++++++++++++++++++++++------
>  1 file changed, 95 insertions(+), 17 deletions(-)
> 
> diff --git a/drivers/hwmon/surface_temp.c b/drivers/hwmon/surface_temp.c
> index 48c3e826713f6..7a2e1f638336c 100644
> --- a/drivers/hwmon/surface_temp.c
> +++ b/drivers/hwmon/surface_temp.c
> @@ -17,6 +17,27 @@
>  
>  /* -- SAM interface. -------------------------------------------------------- */
>  
> +/*
> + * Available sensors are indicated by a 16-bit bitfield, where a 1 marks the
> + * presence of a sensor. So we have at most 16 possible sensors/channels.
> + */
> +#define SSAM_TMP_SENSOR_MAX_COUNT 16
> +
> +/*
> + * All names observed so far are 6 characters long, but there's only
> + * zeros after the name, so perhaps they can be longer. This number reflects
> + * the maximum zero-padded space observed in the returned buffer.
> + */
> +#define SSAM_TMP_SENSOR_NAME_LENGTH 18
> +
> +struct ssam_tmp_get_name_rsp {
> +	__le16 unknown1;
> +	char unknown2;
> +	char name[SSAM_TMP_SENSOR_NAME_LENGTH];
> +} __packed;
> +
> +static_assert(sizeof(struct ssam_tmp_get_name_rsp) == 21);
> +
>  SSAM_DEFINE_SYNC_REQUEST_CL_R(__ssam_tmp_get_available_sensors, __le16, {
>  	.target_category = SSAM_SSH_TC_TMP,
>  	.command_id      = 0x04,
> @@ -27,6 +48,11 @@ SSAM_DEFINE_SYNC_REQUEST_MD_R(__ssam_tmp_get_temperature, __le16, {
>  	.command_id      = 0x01,
>  });
>  
> +SSAM_DEFINE_SYNC_REQUEST_MD_R(__ssam_tmp_get_name, struct ssam_tmp_get_name_rsp, {
> +	.target_category = SSAM_SSH_TC_TMP,
> +	.command_id      = 0x0e,
> +});
> +
>  static int ssam_tmp_get_available_sensors(struct ssam_device *sdev, s16 *sensors)
>  {
>  	__le16 sensors_le;
> @@ -54,12 +80,37 @@ static int ssam_tmp_get_temperature(struct ssam_device *sdev, u8 iid, long *temp
>  	return 0;
>  }
>  
> +static int ssam_tmp_get_name(struct ssam_device *sdev, u8 iid, char *buf, size_t buf_len)
> +{
> +	struct ssam_tmp_get_name_rsp name_rsp;
> +	int status;
> +
> +	status =  __ssam_tmp_get_name(sdev->ctrl, sdev->uid.target, iid, &name_rsp);
> +	if (status)
> +		return status;
> +
> +	/*
> +	 * This should not fail unless the name in the returned struct is not
> +	 * null-terminated or someone changed something in the struct
> +	 * definitions above, since our buffer and struct have the same
> +	 * capacity by design. So if this fails blow this up with a warning.
> +	 * Since the more likely cause is that the returned string isn't
> +	 * null-terminated, we might have received garbage (as opposed to just
> +	 * an incomplete string), so also fail the function.
> +	 */
> +	status = strscpy(buf, name_rsp.name, buf_len);
> +	WARN_ON(status < 0);
> +
> +	return status < 0 ? status : 0;
> +}
> +
>  
>  /* -- Driver.---------------------------------------------------------------- */
>  
>  struct ssam_temp {
>  	struct ssam_device *sdev;
>  	s16 sensors;
> +	char names[SSAM_TMP_SENSOR_MAX_COUNT][SSAM_TMP_SENSOR_NAME_LENGTH];
>  };
>  
>  static umode_t ssam_temp_hwmon_is_visible(const void *data,
> @@ -83,33 +134,47 @@ static int ssam_temp_hwmon_read(struct device *dev,
>  	return ssam_tmp_get_temperature(ssam_temp->sdev, channel + 1, value);
>  }
>  
> +static int ssam_temp_hwmon_read_string(struct device *dev,
> +				       enum hwmon_sensor_types type,
> +				       u32 attr, int channel, const char **str)
> +{
> +	const struct ssam_temp *ssam_temp = dev_get_drvdata(dev);
> +
> +	*str = ssam_temp->names[channel];
> +	return 0;
> +}
> +
>  static const struct hwmon_channel_info * const ssam_temp_hwmon_info[] = {
>  	HWMON_CHANNEL_INFO(chip,
>  			   HWMON_C_REGISTER_TZ),
> -	/* We have at most 16 thermal sensor channels. */
> +	/*
> +	 * We have at most SSAM_TMP_SENSOR_MAX_COUNT = 16 thermal sensor
> +	 * channels.
> +	 */
>  	HWMON_CHANNEL_INFO(temp,
> -			   HWMON_T_INPUT,
> -			   HWMON_T_INPUT,
> -			   HWMON_T_INPUT,
> -			   HWMON_T_INPUT,
> -			   HWMON_T_INPUT,
> -			   HWMON_T_INPUT,
> -			   HWMON_T_INPUT,
> -			   HWMON_T_INPUT,
> -			   HWMON_T_INPUT,
> -			   HWMON_T_INPUT,
> -			   HWMON_T_INPUT,
> -			   HWMON_T_INPUT,
> -			   HWMON_T_INPUT,
> -			   HWMON_T_INPUT,
> -			   HWMON_T_INPUT,
> -			   HWMON_T_INPUT),
> +			   HWMON_T_INPUT | HWMON_T_LABEL,
> +			   HWMON_T_INPUT | HWMON_T_LABEL,
> +			   HWMON_T_INPUT | HWMON_T_LABEL,
> +			   HWMON_T_INPUT | HWMON_T_LABEL,
> +			   HWMON_T_INPUT | HWMON_T_LABEL,
> +			   HWMON_T_INPUT | HWMON_T_LABEL,
> +			   HWMON_T_INPUT | HWMON_T_LABEL,
> +			   HWMON_T_INPUT | HWMON_T_LABEL,
> +			   HWMON_T_INPUT | HWMON_T_LABEL,
> +			   HWMON_T_INPUT | HWMON_T_LABEL,
> +			   HWMON_T_INPUT | HWMON_T_LABEL,
> +			   HWMON_T_INPUT | HWMON_T_LABEL,
> +			   HWMON_T_INPUT | HWMON_T_LABEL,
> +			   HWMON_T_INPUT | HWMON_T_LABEL,
> +			   HWMON_T_INPUT | HWMON_T_LABEL,
> +			   HWMON_T_INPUT | HWMON_T_LABEL),
>  	NULL
>  };
>  
>  static const struct hwmon_ops ssam_temp_hwmon_ops = {
>  	.is_visible = ssam_temp_hwmon_is_visible,
>  	.read = ssam_temp_hwmon_read,
> +	.read_string = ssam_temp_hwmon_read_string,
>  };
>  
>  static const struct hwmon_chip_info ssam_temp_hwmon_chip_info = {
> @@ -122,6 +187,7 @@ static int ssam_temp_probe(struct ssam_device *sdev)
>  	struct ssam_temp *ssam_temp;
>  	struct device *hwmon_dev;
>  	s16 sensors;
> +	int channel;
>  	int status;
>  
>  	status = ssam_tmp_get_available_sensors(sdev, &sensors);
> @@ -135,6 +201,18 @@ static int ssam_temp_probe(struct ssam_device *sdev)
>  	ssam_temp->sdev = sdev;
>  	ssam_temp->sensors = sensors;
>  
> +	/* Retrieve the name for each available sensor. */
> +	for (channel = 0; channel < SSAM_TMP_SENSOR_MAX_COUNT; channel++) {
> +		if (!(sensors & BIT(channel)))
> +			continue;
> +
> +		status = ssam_tmp_get_name(sdev, channel + 1,
> +					   ssam_temp->names[channel],
> +					   SSAM_TMP_SENSOR_NAME_LENGTH);
> +		if (status)
> +			return status;
> +	}
> +
>  	hwmon_dev = devm_hwmon_device_register_with_info(&sdev->dev,
>  			"surface_thermal", ssam_temp, &ssam_temp_hwmon_chip_info,
>  			NULL);