Re: [PATCH] hwmon: (tmp421) Add nfactor support.

[Andre Prendel <andre.prendel@gmx.de>]

On Mon, May 10, 2010 at 10:43:07AM -0400, Jeff Angielski wrote:

Hi Jeff,

A few comments below.
 
> Add support for reading and writing the n-factor correction
> registers.  This is needed to compensate for the characteristics
> of a particular sensor hanging off of the remote channels.
> 
> Signed-off-by: Jeff Angielski <jeff@theptrgroup.com>
> ---
>  drivers/hwmon/tmp421.c |   42 ++++++++++++++++++++++++++++++++++++++++++
>  1 files changed, 42 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/hwmon/tmp421.c b/drivers/hwmon/tmp421.c
> index 738c472..c9e9855 100644
> --- a/drivers/hwmon/tmp421.c
> +++ b/drivers/hwmon/tmp421.c
> @@ -49,6 +49,7 @@ enum chips { tmp421, tmp422, tmp423 };
> 
>  static const u8 TMP421_TEMP_MSB[4]		= { 0x00, 0x01, 0x02, 0x03 };
>  static const u8 TMP421_TEMP_LSB[4]		= { 0x10, 0x11, 0x12, 0x13 };
> +static const u8 TMP421_NFACTOR[3]		= { 0x21, 0x22, 0x23 };
> 
>  /* Flags */
>  #define TMP421_CONFIG_SHUTDOWN			0x40
> @@ -157,6 +158,38 @@ static ssize_t show_fault(struct device *dev,
>  		return sprintf(buf, "0\n");
>  }
> 
> +static ssize_t show_nfactor(struct device *dev,
> +			  struct device_attribute *devattr, char *buf)
> +{
> +	struct i2c_client *client = to_i2c_client(dev);
> +	struct tmp421_data *data = i2c_get_clientdata(client);
> +	int index = to_sensor_dev_attr(devattr)->index;
> +	s8 nfactor;
> +
> +	mutex_lock(&data->update_lock);
> +	nfactor = i2c_smbus_read_byte_data(client, TMP421_NFACTOR[index-1]);

There should be spaces within the array index, [index - 1].

> +	mutex_unlock(&data->update_lock);
> +
> +	return sprintf(buf, "%d\n", nfactor);
> +}

I'de prefer implementing the sysfs access methods in a consistent way (see other functions). That means adding the nfactor register to the tmp421_data structure and using tmp421_update_device() to update the structure.

> +static ssize_t set_nfactor(struct device *dev,
> +		struct device_attribute *devattr,
> +		const char *buf, size_t count)
> +{
> +	struct i2c_client *client = to_i2c_client(dev);
> +	struct tmp421_data *data = i2c_get_clientdata(client);
> +	int index = to_sensor_dev_attr(devattr)->index;
> +	int nfactor = simple_strtol(buf, NULL, 10);
> +
> +	mutex_lock(&data->update_lock);
> +	i2c_smbus_write_byte_data(client, TMP421_NFACTOR[index-1],

Missing spaces in array index again.

> +			SENSORS_LIMIT(nfactor, -128, 127));
> +	mutex_unlock(&data->update_lock);
> +
> +	return count;
> +}
> +
>  static mode_t tmp421_is_visible(struct kobject *kobj, struct attribute *a,
>  				int n)
>  {
> @@ -177,19 +210,28 @@ static mode_t tmp421_is_visible(struct kobject
> *kobj, struct attribute *a,
>  static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, show_temp_value, NULL, 0);
>  static SENSOR_DEVICE_ATTR(temp2_input, S_IRUGO, show_temp_value, NULL, 1);
>  static SENSOR_DEVICE_ATTR(temp2_fault, S_IRUGO, show_fault, NULL, 1);
> +static SENSOR_DEVICE_ATTR(temp2_nfactor, S_IRUGO | S_IWUSR,
> +		show_nfactor, set_nfactor, 1);
>  static SENSOR_DEVICE_ATTR(temp3_input, S_IRUGO, show_temp_value, NULL, 2);
>  static SENSOR_DEVICE_ATTR(temp3_fault, S_IRUGO, show_fault, NULL, 2);
> +static SENSOR_DEVICE_ATTR(temp3_nfactor, S_IRUGO | S_IWUSR,
> +		show_nfactor, set_nfactor, 2);
>  static SENSOR_DEVICE_ATTR(temp4_input, S_IRUGO, show_temp_value, NULL, 3);
>  static SENSOR_DEVICE_ATTR(temp4_fault, S_IRUGO, show_fault, NULL, 3);
> +static SENSOR_DEVICE_ATTR(temp4_nfactor, S_IRUGO | S_IWUSR,
> +		show_nfactor, set_nfactor, 3);
> 
>  static struct attribute *tmp421_attr[] = {
>  	&sensor_dev_attr_temp1_input.dev_attr.attr,
>  	&sensor_dev_attr_temp2_input.dev_attr.attr,
>  	&sensor_dev_attr_temp2_fault.dev_attr.attr,
> +	&sensor_dev_attr_temp2_nfactor.dev_attr.attr,
>  	&sensor_dev_attr_temp3_input.dev_attr.attr,
>  	&sensor_dev_attr_temp3_fault.dev_attr.attr,
> +	&sensor_dev_attr_temp3_nfactor.dev_attr.attr,
>  	&sensor_dev_attr_temp4_input.dev_attr.attr,
>  	&sensor_dev_attr_temp4_fault.dev_attr.attr,
> +	&sensor_dev_attr_temp4_nfactor.dev_attr.attr,
>  	NULL
>  };
> 

Regards,
Andre

PS: CC'ed lm-sensors list