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Date:   Tue, 7 Jul 2020 14:28:14 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Chu Lin <linchuyuan@...gle.com>
Cc:     belgaied@...gle.com, jasonling@...gle.com, jdelvare@...e.com,
        linux-hwmon@...r.kernel.org, linux-kernel@...r.kernel.org,
        zhongqil@...gle.com
Subject: Re: [PATCH v4] hwmon:max6697: Allow max6581 to create tempX_offset

On Tue, Jul 07, 2020 at 05:15:28PM +0000, Chu Lin wrote:
> Testing:
> echo 16250 > temp2_offset
> cat temp2_offset
> 16250
> 
> echo 17500 > temp3_offset
> cat temp3_offset
> 17500
> cat temp4_offset
> 0
> cat temp2_offset
> 17500
> 
> echo 0 > temp2_offset
> cat temp2_offset
> 0
> cat temp3_offset
> 17500
> 
> echo -0 > temp2_offset
> cat temp2_offset
> 0
> 
> echo -100000 > temp2_offset
> cat temp2_input
> 4875
> 
> echo 10000 > temp2_offset
> cat temp2_input
> 47125
> 
> echo -2000 > temp2_offset
> cat temp2_input
> 34875
> 
> echo -0 > temp2_offset
> cat temp2_input
> 37000
> 
> Signed-off-by: Chu Lin <linchuyuan@...gle.com>

Applied, after fixing a checkpatch warning (unnecessary { }).

Thanks,
Guenter

> ---
> ChangeLog v3 -> v4:
>   - Check if a particular channel is disabled/enabled before flipping
>     state
>   - Make sure the RW operation is mux protected to avoid the situation
>     where the user is able to modify the offset select value after it is
>     read
>   - indentation cleanup
>   - Use label to make sure the lock is released
>   - Fix a typo where the channel index should be /7 instead of /8
> 
> ChangeLog v2 -> v3:
>   - Use reverse christmas tree order convension
>   - Fix the type issue where comparision is always true
>   - Change the line limit to 100 char instead of 80 char
> 
> ChangeLog v1 -> v2:
>   - Simplify the offset reg raw value to milli ceisus conversion
>   - Substitute the temp1_offset with dummy attr
>   - Avoid using double negative in the macro definition
>   - Return the actual error when i2c read/write is failed
>   - clamp the value to MAX or MIN respectively if an out of range input is given
>   - Provide mux protection when multiple i2c accesses is required
> 
>  drivers/hwmon/max6697.c | 97 ++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 95 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/hwmon/max6697.c b/drivers/hwmon/max6697.c
> index 64122eb38060..5b4e72d8df00 100644
> --- a/drivers/hwmon/max6697.c
> +++ b/drivers/hwmon/max6697.c
> @@ -57,6 +57,8 @@ static const u8 MAX6697_REG_CRIT[] = {
>  #define MAX6581_REG_IDEALITY_SELECT	0x4c
>  #define MAX6581_REG_OFFSET		0x4d
>  #define MAX6581_REG_OFFSET_SELECT	0x4e
> +#define MAX6581_OFFSET_MIN		-31750
> +#define MAX6581_OFFSET_MAX		31750
>  
>  #define MAX6697_CONV_TIME		156	/* ms per channel, worst case */
>  
> @@ -172,6 +174,11 @@ static const struct max6697_chip_data max6697_chip_data[] = {
>  	},
>  };
>  
> +static inline int max6581_offset_to_millic(int val)
> +{
> +	return sign_extend32(val, 7) * 250;
> +}
> +
>  static struct max6697_data *max6697_update_device(struct device *dev)
>  {
>  	struct max6697_data *data = dev_get_drvdata(dev);
> @@ -317,6 +324,71 @@ static ssize_t temp_store(struct device *dev,
>  	return ret < 0 ? ret : count;
>  }
>  
> +static ssize_t offset_store(struct device *dev, struct device_attribute *devattr, const char *buf,
> +			    size_t count)
> +{
> +	int val, ret, index, select;
> +	struct max6697_data *data;
> +	bool channel_enabled;
> +	long temp;
> +
> +	index = to_sensor_dev_attr(devattr)->index;
> +	data = dev_get_drvdata(dev);
> +	ret = kstrtol(buf, 10, &temp);
> +	if (ret < 0)
> +		return ret;
> +
> +	mutex_lock(&data->update_lock);
> +	select = i2c_smbus_read_byte_data(data->client, MAX6581_REG_OFFSET_SELECT);
> +	if (select < 0) {
> +		ret = select;
> +		goto abort;
> +	}
> +	channel_enabled = (select & (1 << (index - 1)));
> +	temp = clamp_val(temp, MAX6581_OFFSET_MIN, MAX6581_OFFSET_MAX);
> +	val = DIV_ROUND_CLOSEST(temp, 250);
> +	/* disable the offset for channel if the new offset is 0 */
> +	if (val == 0) {
> +		if (channel_enabled)
> +			ret = i2c_smbus_write_byte_data(data->client, MAX6581_REG_OFFSET_SELECT,
> +							select & ~(1 << (index - 1)));
> +		ret = ret < 0 ? ret : count;
> +		goto abort;
> +	}
> +	if (!channel_enabled) {
> +		ret = i2c_smbus_write_byte_data(data->client, MAX6581_REG_OFFSET_SELECT,
> +						select | (1 << (index - 1)));
> +		if (ret < 0)
> +			goto abort;
> +	}
> +	ret = i2c_smbus_write_byte_data(data->client, MAX6581_REG_OFFSET, val);
> +	ret = ret < 0 ? ret : count;
> +
> +abort:
> +	mutex_unlock(&data->update_lock);
> +	return ret;
> +}
> +
> +static ssize_t offset_show(struct device *dev, struct device_attribute *devattr, char *buf)
> +{
> +	struct max6697_data *data;
> +	int select, ret, index;
> +
> +	index = to_sensor_dev_attr(devattr)->index;
> +	data = dev_get_drvdata(dev);
> +	mutex_lock(&data->update_lock);
> +	select = i2c_smbus_read_byte_data(data->client, MAX6581_REG_OFFSET_SELECT);
> +	if (select < 0) {
> +		ret = select;
> +	} else if (select & (1 << (index - 1))) {
> +		ret = i2c_smbus_read_byte_data(data->client, MAX6581_REG_OFFSET);
> +	} else {
> +		ret = 0;
> +	}
> +	mutex_unlock(&data->update_lock);
> +	return ret < 0 ? ret : sprintf(buf, "%d\n", max6581_offset_to_millic(ret));
> +}
> +
>  static SENSOR_DEVICE_ATTR_RO(temp1_input, temp_input, 0);
>  static SENSOR_DEVICE_ATTR_2_RW(temp1_max, temp, 0, MAX6697_TEMP_MAX);
>  static SENSOR_DEVICE_ATTR_2_RW(temp1_crit, temp, 0, MAX6697_TEMP_CRIT);
> @@ -375,6 +447,15 @@ static SENSOR_DEVICE_ATTR_RO(temp6_fault, alarm, 5);
>  static SENSOR_DEVICE_ATTR_RO(temp7_fault, alarm, 6);
>  static SENSOR_DEVICE_ATTR_RO(temp8_fault, alarm, 7);
>  
> +/* There is no offset for local temperature so starting from temp2 */
> +static SENSOR_DEVICE_ATTR_RW(temp2_offset, offset, 1);
> +static SENSOR_DEVICE_ATTR_RW(temp3_offset, offset, 2);
> +static SENSOR_DEVICE_ATTR_RW(temp4_offset, offset, 3);
> +static SENSOR_DEVICE_ATTR_RW(temp5_offset, offset, 4);
> +static SENSOR_DEVICE_ATTR_RW(temp6_offset, offset, 5);
> +static SENSOR_DEVICE_ATTR_RW(temp7_offset, offset, 6);
> +static SENSOR_DEVICE_ATTR_RW(temp8_offset, offset, 7);
> +
>  static DEVICE_ATTR(dummy, 0, NULL, NULL);
>  
>  static umode_t max6697_is_visible(struct kobject *kobj, struct attribute *attr,
> @@ -383,8 +464,8 @@ static umode_t max6697_is_visible(struct kobject *kobj, struct attribute *attr,
>  	struct device *dev = container_of(kobj, struct device, kobj);
>  	struct max6697_data *data = dev_get_drvdata(dev);
>  	const struct max6697_chip_data *chip = data->chip;
> -	int channel = index / 6;	/* channel number */
> -	int nr = index % 6;		/* attribute index within channel */
> +	int channel = index / 7;	/* channel number */
> +	int nr = index % 7;		/* attribute index within channel */
>  
>  	if (channel >= chip->channels)
>  		return 0;
> @@ -393,6 +474,10 @@ static umode_t max6697_is_visible(struct kobject *kobj, struct attribute *attr,
>  		return 0;
>  	if (nr == 5 && !(chip->have_fault & (1 << channel)))
>  		return 0;
> +	/* offset reg is only supported on max6581 remote channels */
> +	if (nr == 6)
> +		if (data->type != max6581 || channel == 0)
> +			return 0;
>  
>  	return attr->mode;
>  }
> @@ -409,6 +494,7 @@ static struct attribute *max6697_attributes[] = {
>  	&sensor_dev_attr_temp1_crit.dev_attr.attr,
>  	&sensor_dev_attr_temp1_crit_alarm.dev_attr.attr,
>  	&dev_attr_dummy.attr,
> +	&dev_attr_dummy.attr,
>  
>  	&sensor_dev_attr_temp2_input.dev_attr.attr,
>  	&sensor_dev_attr_temp2_max.dev_attr.attr,
> @@ -416,6 +502,7 @@ static struct attribute *max6697_attributes[] = {
>  	&sensor_dev_attr_temp2_crit.dev_attr.attr,
>  	&sensor_dev_attr_temp2_crit_alarm.dev_attr.attr,
>  	&sensor_dev_attr_temp2_fault.dev_attr.attr,
> +	&sensor_dev_attr_temp2_offset.dev_attr.attr,
>  
>  	&sensor_dev_attr_temp3_input.dev_attr.attr,
>  	&sensor_dev_attr_temp3_max.dev_attr.attr,
> @@ -423,6 +510,7 @@ static struct attribute *max6697_attributes[] = {
>  	&sensor_dev_attr_temp3_crit.dev_attr.attr,
>  	&sensor_dev_attr_temp3_crit_alarm.dev_attr.attr,
>  	&sensor_dev_attr_temp3_fault.dev_attr.attr,
> +	&sensor_dev_attr_temp3_offset.dev_attr.attr,
>  
>  	&sensor_dev_attr_temp4_input.dev_attr.attr,
>  	&sensor_dev_attr_temp4_max.dev_attr.attr,
> @@ -430,6 +518,7 @@ static struct attribute *max6697_attributes[] = {
>  	&sensor_dev_attr_temp4_crit.dev_attr.attr,
>  	&sensor_dev_attr_temp4_crit_alarm.dev_attr.attr,
>  	&sensor_dev_attr_temp4_fault.dev_attr.attr,
> +	&sensor_dev_attr_temp4_offset.dev_attr.attr,
>  
>  	&sensor_dev_attr_temp5_input.dev_attr.attr,
>  	&sensor_dev_attr_temp5_max.dev_attr.attr,
> @@ -437,6 +526,7 @@ static struct attribute *max6697_attributes[] = {
>  	&sensor_dev_attr_temp5_crit.dev_attr.attr,
>  	&sensor_dev_attr_temp5_crit_alarm.dev_attr.attr,
>  	&sensor_dev_attr_temp5_fault.dev_attr.attr,
> +	&sensor_dev_attr_temp5_offset.dev_attr.attr,
>  
>  	&sensor_dev_attr_temp6_input.dev_attr.attr,
>  	&sensor_dev_attr_temp6_max.dev_attr.attr,
> @@ -444,6 +534,7 @@ static struct attribute *max6697_attributes[] = {
>  	&sensor_dev_attr_temp6_crit.dev_attr.attr,
>  	&sensor_dev_attr_temp6_crit_alarm.dev_attr.attr,
>  	&sensor_dev_attr_temp6_fault.dev_attr.attr,
> +	&sensor_dev_attr_temp6_offset.dev_attr.attr,
>  
>  	&sensor_dev_attr_temp7_input.dev_attr.attr,
>  	&sensor_dev_attr_temp7_max.dev_attr.attr,
> @@ -451,6 +542,7 @@ static struct attribute *max6697_attributes[] = {
>  	&sensor_dev_attr_temp7_crit.dev_attr.attr,
>  	&sensor_dev_attr_temp7_crit_alarm.dev_attr.attr,
>  	&sensor_dev_attr_temp7_fault.dev_attr.attr,
> +	&sensor_dev_attr_temp7_offset.dev_attr.attr,
>  
>  	&sensor_dev_attr_temp8_input.dev_attr.attr,
>  	&sensor_dev_attr_temp8_max.dev_attr.attr,
> @@ -458,6 +550,7 @@ static struct attribute *max6697_attributes[] = {
>  	&sensor_dev_attr_temp8_crit.dev_attr.attr,
>  	&sensor_dev_attr_temp8_crit_alarm.dev_attr.attr,
>  	&sensor_dev_attr_temp8_fault.dev_attr.attr,
> +	&sensor_dev_attr_temp8_offset.dev_attr.attr,
>  	NULL
>  };
>  

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