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

From: Jeff Angielski <[email-masked]>
Date: Mon, 10 May 2010 10:43:07 -0400

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

-- 
1.7.0.4

-- 
Jeff Angielski
The PTR Group
www.theptrgroup.com