Subject: Re: [lm-sensors] [PATCH] hwmon: (tmp421) Add nfactor support (2nd attempt)

From: Andre Prendel <[email-masked]>
Date: Thu, 20 May 2010 20:50:35 +0200

On Wed, May 19, 2010 at 01:13:04PM -0400, Jeff Angielski wrote:
> On 05/19/2010 03:26 AM, Andre Prendel wrote:
> > Ok, so there is only one remaining task :) Please update the documentation under
> > Documentation/hwmon/tmp421. Then you will get my Acked-by.
> 
> Documentation is updated in this patch along with the source file.
> 
> There is a small cosmetic change in this patch. I changed the name of the 
> sysfs entry and internal variable name from nfactor to n_adjust.  This was 
> done to make sure the users know we are modifying the N[adjust] parameter 
> in the nfactor corrections register and not the actual nfactor itself. I
> also changed the reference to the register from NFACTOR to N_CORRECT since
> the datasheet uses that name for the register in question.
> 
> I think the method of using the nfactor adjustment value is specific to this
> chipset.  Consequently, it's not appropriate to go into the general documentation.
> 

You made a careless mistake, see below. Please fix this and resend the patch
again. Then I added my Acked-by and I think Jean will schedule the patch for
2.6.35 (after another review of course :)) 
 
> 
> 
> 
> >From 61f1c203620b06463695b399bae27a884008f169 Mon Sep 17 00:00:00 2001
> From: Jeff Angielski <[email-masked]>
> Date: Mon, 10 May 2010 10:26:34 -0400
> Subject: [PATCH] hwmon: (tmp421) Add nfactor support
> 
> 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 <[email-masked]>
> ---
>  Documentation/hwmon/tmp421 |   19 +++++++++++++++++++
>  drivers/hwmon/tmp421.c     |   41 +++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 60 insertions(+), 0 deletions(-)
> 
> diff --git a/Documentation/hwmon/tmp421 b/Documentation/hwmon/tmp421
> index 0cf07f8..668228a 100644
> --- a/Documentation/hwmon/tmp421
> +++ b/Documentation/hwmon/tmp421
> @@ -17,6 +17,7 @@ Supported chips:
>  
>  Authors:
>  	Andre Prendel <[email-masked]>
> +	Jeff Angielski <[email-masked]>
>  
>  Description
>  -----------
> @@ -34,3 +35,21 @@ the temperature values via the following sysfs files:
>  
>  temp[1-4]_input
>  temp[2-4]_fault
> +
> +The chips allow the user to adjust the n-factor value that is used
> +when converting the remote channel measurements to temperature. The
> +adjustment has a range of -128 to +127 that yields an effective
> +n-factor range of 0.706542 to 1.747977.  The power on reset value
> +for the adjustment is 0 which results in an n-factor of 1.008.
> +
> +The effective n-factor is calculated according to the following
> +equation:
> +
> +n_factor = (1.008 * 300) / (300 - nfactor_adjust)
> +
> +The driver exports the n-factor adjustment value via the following 
> +sysfs files:
> +
> +temp[2-4]_n_adjust
> +
> +
> diff --git a/drivers/hwmon/tmp421.c b/drivers/hwmon/tmp421.c
> index 738c472..83edbc8 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_N_CORRECT[3]		= { 0x21, 0x22, 0x23 };
>  
>  /* Flags */
>  #define TMP421_CONFIG_SHUTDOWN			0x40
> @@ -76,6 +77,7 @@ struct tmp421_data {
>  	int channels;
>  	u8 config;
>  	s16 temp[4];
> +	s8 n_adjust[3];
>  };
>  
>  static int temp_from_s16(s16 reg)
> @@ -115,6 +117,10 @@ static struct tmp421_data *tmp421_update_device(struct device *dev)
>  			data->temp[i] |= i2c_smbus_read_byte_data(client,
>  				TMP421_TEMP_LSB[i]);
>  		}
> +		for (i = 1; i < data->channels; i++) {
> +			data->n_adjust[i - 1] = i2c_smbus_read_byte_data(client,
> +				TMP421_N_CORRECT[i - 1]);
> +		}
>  		data->last_updated = jiffies;
>  		data->valid = 1;
>  	}
> @@ -157,6 +163,32 @@ static ssize_t show_fault(struct device *dev,
>  		return sprintf(buf, "0\n");
>  }
>  
> +static ssize_t show_n_adjust(struct device *dev,
> +			     struct device_attribute *devattr, char *buf)
> +{
> +	int index = to_sensor_dev_attr(devattr)->index;
> +	struct tmp421_data *data = tmp421_update_device(dev);
> +
> +	return sprintf(buf, "%d\n", data->n_adjust[index - 1]);
> +}
> +
> +static ssize_t set_n_adjust(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 n_adjust= simple_strtol(buf, NULL, 10);

Missing space in front of '='.

> +
> +	mutex_lock(&data->update_lock);
> +	i2c_smbus_write_byte_data(client, TMP421_N_CORRECT[index - 1],
> +				  SENSORS_LIMIT(n_adjust, -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 +209,28 @@ 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_n_adjust, S_IRUSR | S_IWUSR | S_IRGRP,
> +			  show_n_adjust, set_n_adjust, 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_n_adjust, S_IRUSR | S_IWUSR | S_IRGRP,
> +			  show_n_adjust, set_n_adjust, 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_n_adjust, S_IRUSR | S_IWUSR | S_IRGRP,
> +			  show_n_adjust, set_n_adjust, 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_n_adjust.dev_attr.attr,
>  	&sensor_dev_attr_temp3_input.dev_attr.attr,
>  	&sensor_dev_attr_temp3_fault.dev_attr.attr,
> +	&sensor_dev_attr_temp3_n_adjust.dev_attr.attr,
>  	&sensor_dev_attr_temp4_input.dev_attr.attr,
>  	&sensor_dev_attr_temp4_fault.dev_attr.attr,
> +	&sensor_dev_attr_temp4_n_adjust.dev_attr.attr,
>  	NULL
>  };
>

Thanks,
Andre