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Subject: Re: [PATCH V1 2/2] hwmon: (powr1220) add scaled voltage support
To:     Oleksij Rempel <o.rempel@pengutronix.de>,
        Jean Delvare <jdelvare@suse.com>,
        Markus Pietrek <mpie@msc-ge.com>
Cc:     kernel@pengutronix.de, linux-hwmon@vger.kernel.org,
        linux-kernel@vger.kernel.org
References: <20200127102540.31742-1-o.rempel@pengutronix.de>
 <20200127102540.31742-2-o.rempel@pengutronix.de>
From:   Guenter Roeck <linux@roeck-us.net>
Message-ID: <f7a357d3-c8c3-a71a-ebc8-bc2d37c7c086@roeck-us.net>
Date:   Mon, 27 Jan 2020 05:52:00 -0800
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On 1/27/20 2:25 AM, Oleksij Rempel wrote:
> From: Markus Pietrek <mpie@msc-ge.com>
> 
> On some (or may be all?) boards, voltage measured by powr1220 do not
> reflect real system configuration. This patch provides scale option to
> set board specific configuration.
> 
> Signed-off-by: Markus Pietrek <mpie@msc-ge.com>
> Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
> ---

NACK; scaling is what sensors3.conf is for. Also, we most definintely
won't permit out-of-ABI attributes for something like this.

Guenter

>   drivers/hwmon/powr1220.c | 155 +++++++++++++++++++++++++++++++++++++++
>   1 file changed, 155 insertions(+)
> 
> diff --git a/drivers/hwmon/powr1220.c b/drivers/hwmon/powr1220.c
> index ad7a82f132e6..7cb2a6d3b3d8 100644
> --- a/drivers/hwmon/powr1220.c
> +++ b/drivers/hwmon/powr1220.c
> @@ -74,6 +74,14 @@ enum powr1220_adc_values {
>   	MAX_POWR1220_ADC_VALUES
>   };
>   
> +/* Real value = (measured-value * factor) / divisor.
> + * A divisor of 0 disables scaling and is identical to factor==1 && divisor==1.
> + */
> +struct adc_scale {
> +	int factor;
> +	int divisor;
> +};
> +
>   struct powr1220_data {
>   	struct i2c_client *client;
>   	struct mutex update_lock;
> @@ -84,6 +92,7 @@ struct powr1220_data {
>   	/* values */
>   	int adc_maxes[MAX_POWR1220_ADC_VALUES];
>   	int adc_values[MAX_POWR1220_ADC_VALUES];
> +	struct adc_scale adc_scales[MAX_POWR1220_ADC_VALUES];
>   };
>   
>   static const char * const input_names[] = {
> @@ -184,6 +193,29 @@ static ssize_t powr1220_voltage_show(struct device *dev,
>   	return sprintf(buf, "%d\n", adc_val);
>   }
>   
> +static ssize_t powr1220_scaled_voltage_show(struct device *dev,
> +	struct device_attribute *dev_attr, char *buf)
> +{
> +	struct sensor_device_attribute *attr = to_sensor_dev_attr(dev_attr);
> +	struct powr1220_data *data = dev_get_drvdata(dev);
> +	int adc_val = powr1220_read_adc(dev, attr->index);
> +	struct adc_scale *scale;
> +
> +	if (adc_val < 0)
> +		return adc_val;
> +
> +	scale = &data->adc_scales[attr->index];
> +	if (scale->divisor) {
> +		int64_t lscaled = adc_val;
> +
> +		lscaled *= scale->factor;
> +		lscaled /= scale->divisor;
> +		adc_val = (int) lscaled;
> +	}
> +
> +	return sprintf(buf, "%d\n", adc_val);
> +}
> +
>   /* Shows the maximum setting associated with the specified ADC channel */
>   static ssize_t powr1220_max_show(struct device *dev,
>   				 struct device_attribute *dev_attr, char *buf)
> @@ -204,6 +236,38 @@ static ssize_t powr1220_label_show(struct device *dev,
>   	return sprintf(buf, "%s\n", input_names[attr->index]);
>   }
>   
> +/* Shows the scale for the read value.
> + * real value = (measured value * factor) / divisor. n/0 means scaling disabled
> + * and raw values are printed.
> + */
> +static ssize_t powr1220_scale_show(struct device *dev,
> +	struct device_attribute *dev_attr, char *buf)
> +{
> +	struct sensor_device_attribute *attr = to_sensor_dev_attr(dev_attr);
> +	struct powr1220_data *data = dev_get_drvdata(dev);
> +
> +	return sprintf(buf, "%d/%d\n", data->adc_scales[attr->index].factor,
> +		       data->adc_scales[attr->index].divisor);
> +}
> +
> +static ssize_t powr1220_scale_store(struct device *dev,
> +				    struct device_attribute *dev_attr,
> +				    const char *buf, size_t count)
> +{
> +	struct sensor_device_attribute *attr = to_sensor_dev_attr(dev_attr);
> +	struct powr1220_data *data = dev_get_drvdata(dev);
> +	int factor;
> +	int divisor;
> +
> +	if (sscanf(buf, "%d/%d", &factor, &divisor) != 2)
> +		return -EINVAL;
> +
> +	data->adc_scales[attr->index].factor = factor;
> +	data->adc_scales[attr->index].divisor = divisor;
> +
> +	return count;
> +}
> +
>   static SENSOR_DEVICE_ATTR_RO(in0_input, powr1220_voltage, VMON1);
>   static SENSOR_DEVICE_ATTR_RO(in1_input, powr1220_voltage, VMON2);
>   static SENSOR_DEVICE_ATTR_RO(in2_input, powr1220_voltage, VMON3);
> @@ -219,6 +283,26 @@ static SENSOR_DEVICE_ATTR_RO(in11_input, powr1220_voltage, VMON12);
>   static SENSOR_DEVICE_ATTR_RO(in12_input, powr1220_voltage, VCCA);
>   static SENSOR_DEVICE_ATTR_RO(in13_input, powr1220_voltage, VCCINP);
>   
> +static SENSOR_DEVICE_ATTR_RO(in0_scaled_input, powr1220_scaled_voltage, VMON1);
> +static SENSOR_DEVICE_ATTR_RO(in1_scaled_input, powr1220_scaled_voltage, VMON2);
> +static SENSOR_DEVICE_ATTR_RO(in2_scaled_input, powr1220_scaled_voltage, VMON3);
> +static SENSOR_DEVICE_ATTR_RO(in3_scaled_input, powr1220_scaled_voltage, VMON4);
> +static SENSOR_DEVICE_ATTR_RO(in4_scaled_input, powr1220_scaled_voltage, VMON5);
> +static SENSOR_DEVICE_ATTR_RO(in5_scaled_input, powr1220_scaled_voltage, VMON6);
> +static SENSOR_DEVICE_ATTR_RO(in6_scaled_input, powr1220_scaled_voltage, VMON7);
> +static SENSOR_DEVICE_ATTR_RO(in7_scaled_input, powr1220_scaled_voltage, VMON8);
> +static SENSOR_DEVICE_ATTR_RO(in8_scaled_input, powr1220_scaled_voltage, VMON9);
> +static SENSOR_DEVICE_ATTR_RO(in9_scaled_input, powr1220_scaled_voltage,
> +			     VMON10);
> +static SENSOR_DEVICE_ATTR_RO(in10_scaled_input, powr1220_scaled_voltage,
> +			     VMON11);
> +static SENSOR_DEVICE_ATTR_RO(in11_scaled_input, powr1220_scaled_voltage,
> +			     VMON12);
> +static SENSOR_DEVICE_ATTR_RO(in12_scaled_input, powr1220_scaled_voltage,
> +			     VCCA);
> +static SENSOR_DEVICE_ATTR_RO(in13_scaled_input, powr1220_scaled_voltage,
> +			     VCCINP);
> +
>   static SENSOR_DEVICE_ATTR_RO(in0_highest, powr1220_max, VMON1);
>   static SENSOR_DEVICE_ATTR_RO(in1_highest, powr1220_max, VMON2);
>   static SENSOR_DEVICE_ATTR_RO(in2_highest, powr1220_max, VMON3);
> @@ -249,6 +333,21 @@ static SENSOR_DEVICE_ATTR_RO(in11_label, powr1220_label, VMON12);
>   static SENSOR_DEVICE_ATTR_RO(in12_label, powr1220_label, VCCA);
>   static SENSOR_DEVICE_ATTR_RO(in13_label, powr1220_label, VCCINP);
>   
> +static SENSOR_DEVICE_ATTR_RW(in0_scale, powr1220_scale, VMON1);
> +static SENSOR_DEVICE_ATTR_RW(in1_scale, powr1220_scale, VMON2);
> +static SENSOR_DEVICE_ATTR_RW(in2_scale, powr1220_scale, VMON3);
> +static SENSOR_DEVICE_ATTR_RW(in3_scale, powr1220_scale, VMON4);
> +static SENSOR_DEVICE_ATTR_RW(in4_scale, powr1220_scale, VMON5);
> +static SENSOR_DEVICE_ATTR_RW(in5_scale, powr1220_scale, VMON6);
> +static SENSOR_DEVICE_ATTR_RW(in6_scale, powr1220_scale, VMON7);
> +static SENSOR_DEVICE_ATTR_RW(in7_scale, powr1220_scale, VMON8);
> +static SENSOR_DEVICE_ATTR_RW(in8_scale, powr1220_scale, VMON9);
> +static SENSOR_DEVICE_ATTR_RW(in9_scale, powr1220_scale, VMON10);
> +static SENSOR_DEVICE_ATTR_RW(in10_scale, powr1220_scale, VMON11);
> +static SENSOR_DEVICE_ATTR_RW(in11_scale, powr1220_scale, VMON12);
> +static SENSOR_DEVICE_ATTR_RW(in12_scale, powr1220_scale, VCCA);
> +static SENSOR_DEVICE_ATTR_RW(in13_scale, powr1220_scale, VCCINP);
> +
>   static struct attribute *powr1014_attrs[] = {
>   	&sensor_dev_attr_in0_input.dev_attr.attr,
>   	&sensor_dev_attr_in1_input.dev_attr.attr,
> @@ -263,6 +362,19 @@ static struct attribute *powr1014_attrs[] = {
>   	&sensor_dev_attr_in12_input.dev_attr.attr,
>   	&sensor_dev_attr_in13_input.dev_attr.attr,
>   
> +	&sensor_dev_attr_in0_scaled_input.dev_attr.attr,
> +	&sensor_dev_attr_in1_scaled_input.dev_attr.attr,
> +	&sensor_dev_attr_in2_scaled_input.dev_attr.attr,
> +	&sensor_dev_attr_in3_scaled_input.dev_attr.attr,
> +	&sensor_dev_attr_in4_scaled_input.dev_attr.attr,
> +	&sensor_dev_attr_in5_scaled_input.dev_attr.attr,
> +	&sensor_dev_attr_in6_scaled_input.dev_attr.attr,
> +	&sensor_dev_attr_in7_scaled_input.dev_attr.attr,
> +	&sensor_dev_attr_in8_scaled_input.dev_attr.attr,
> +	&sensor_dev_attr_in9_scaled_input.dev_attr.attr,
> +	&sensor_dev_attr_in12_scaled_input.dev_attr.attr,
> +	&sensor_dev_attr_in13_scaled_input.dev_attr.attr,
> +
>   	&sensor_dev_attr_in0_highest.dev_attr.attr,
>   	&sensor_dev_attr_in1_highest.dev_attr.attr,
>   	&sensor_dev_attr_in2_highest.dev_attr.attr,
> @@ -289,6 +401,19 @@ static struct attribute *powr1014_attrs[] = {
>   	&sensor_dev_attr_in12_label.dev_attr.attr,
>   	&sensor_dev_attr_in13_label.dev_attr.attr,
>   
> +	&sensor_dev_attr_in0_scale.dev_attr.attr,
> +	&sensor_dev_attr_in1_scale.dev_attr.attr,
> +	&sensor_dev_attr_in2_scale.dev_attr.attr,
> +	&sensor_dev_attr_in3_scale.dev_attr.attr,
> +	&sensor_dev_attr_in4_scale.dev_attr.attr,
> +	&sensor_dev_attr_in5_scale.dev_attr.attr,
> +	&sensor_dev_attr_in6_scale.dev_attr.attr,
> +	&sensor_dev_attr_in7_scale.dev_attr.attr,
> +	&sensor_dev_attr_in8_scale.dev_attr.attr,
> +	&sensor_dev_attr_in9_scale.dev_attr.attr,
> +	&sensor_dev_attr_in12_scale.dev_attr.attr,
> +	&sensor_dev_attr_in13_scale.dev_attr.attr,
> +
>   	NULL
>   };
>   
> @@ -310,6 +435,21 @@ static struct attribute *powr1220_attrs[] = {
>   	&sensor_dev_attr_in12_input.dev_attr.attr,
>   	&sensor_dev_attr_in13_input.dev_attr.attr,
>   
> +	&sensor_dev_attr_in0_scaled_input.dev_attr.attr,
> +	&sensor_dev_attr_in1_scaled_input.dev_attr.attr,
> +	&sensor_dev_attr_in2_scaled_input.dev_attr.attr,
> +	&sensor_dev_attr_in3_scaled_input.dev_attr.attr,
> +	&sensor_dev_attr_in4_scaled_input.dev_attr.attr,
> +	&sensor_dev_attr_in5_scaled_input.dev_attr.attr,
> +	&sensor_dev_attr_in6_scaled_input.dev_attr.attr,
> +	&sensor_dev_attr_in7_scaled_input.dev_attr.attr,
> +	&sensor_dev_attr_in8_scaled_input.dev_attr.attr,
> +	&sensor_dev_attr_in9_scaled_input.dev_attr.attr,
> +	&sensor_dev_attr_in10_scaled_input.dev_attr.attr,
> +	&sensor_dev_attr_in11_scaled_input.dev_attr.attr,
> +	&sensor_dev_attr_in12_scaled_input.dev_attr.attr,
> +	&sensor_dev_attr_in13_scaled_input.dev_attr.attr,
> +
>   	&sensor_dev_attr_in0_highest.dev_attr.attr,
>   	&sensor_dev_attr_in1_highest.dev_attr.attr,
>   	&sensor_dev_attr_in2_highest.dev_attr.attr,
> @@ -340,6 +480,21 @@ static struct attribute *powr1220_attrs[] = {
>   	&sensor_dev_attr_in12_label.dev_attr.attr,
>   	&sensor_dev_attr_in13_label.dev_attr.attr,
>   
> +	&sensor_dev_attr_in0_scale.dev_attr.attr,
> +	&sensor_dev_attr_in1_scale.dev_attr.attr,
> +	&sensor_dev_attr_in2_scale.dev_attr.attr,
> +	&sensor_dev_attr_in3_scale.dev_attr.attr,
> +	&sensor_dev_attr_in4_scale.dev_attr.attr,
> +	&sensor_dev_attr_in5_scale.dev_attr.attr,
> +	&sensor_dev_attr_in6_scale.dev_attr.attr,
> +	&sensor_dev_attr_in7_scale.dev_attr.attr,
> +	&sensor_dev_attr_in8_scale.dev_attr.attr,
> +	&sensor_dev_attr_in9_scale.dev_attr.attr,
> +	&sensor_dev_attr_in10_scale.dev_attr.attr,
> +	&sensor_dev_attr_in11_scale.dev_attr.attr,
> +	&sensor_dev_attr_in12_scale.dev_attr.attr,
> +	&sensor_dev_attr_in13_scale.dev_attr.attr,
> +
>   	NULL
>   };
>   
>