[lm-sensors] hwmon: (it87) Fix thermal sensor type values

[Jean Delvare]

The it87 driver doesn't follow the standard sensor type values as
documented in Documentation/hwmon/sysfs-interface. It uses value 2 for
thermistors instead of value 4. This causes "sensors" to tell the user
that the chip is setup for a transistor while it is actually setup for
a thermistor.

Using value 4 for thermistors solves the problem. For compatibility
reasons, we still accept value 2 but emit a warning message so that
users update their configuration files.

Signed-off-by: Jean Delvare <khali at linux-fr.org>
---
For users of lm-sensors <= 2.10.7, this change will cause the
thermistors to be reported as "invalid". I've just fixed that in SVN.
For this reason, I do not want to push the it87 driver fix into the
kernel immediately. Let's wait for lm-sensors 2.10.8 to be released
first. In practice, this means that the it87 driver will be fixed in
kernel 2.6.28.

 Documentation/hwmon/it87 |    4 ++--
 drivers/hwmon/it87.c     |   11 ++++++++---
 2 files changed, 10 insertions(+), 5 deletions(-)

--- linux-2.6.27-rc7.orig/Documentation/hwmon/it87	2008-08-13 09:50:46.000000000 +0200
+++ linux-2.6.27-rc7/Documentation/hwmon/it87	2008-09-26 17:43:34.000000000 +0200
@@ -136,10 +136,10 @@ once-only alarms.
 The IT87xx only updates its values each 1.5 seconds; reading it more often
 will do no harm, but will return 'old' values.
 
-To change sensor N to a thermistor, 'echo 2 > tempN_type' where N is 1, 2,
+To change sensor N to a thermistor, 'echo 4 > tempN_type' where N is 1, 2,
 or 3. To change sensor N to a thermal diode, 'echo 3 > tempN_type'.
 Give 0 for unused sensor. Any other value is invalid. To configure this at
-startup, consult lm_sensors's /etc/sensors.conf. (2 = thermistor;
+startup, consult lm_sensors's /etc/sensors.conf. (4 = thermistor;
 3 = thermal diode)
 
 
--- linux-2.6.27-rc7.orig/drivers/hwmon/it87.c	2008-09-26 09:50:16.000000000 +0200
+++ linux-2.6.27-rc7/drivers/hwmon/it87.c	2008-09-27 10:01:44.000000000 +0200
@@ -477,7 +477,7 @@ static ssize_t show_sensor(struct device
 	if (reg & (1 << nr))
 		return sprintf(buf, "3\n");  /* thermal diode */
 	if (reg & (8 << nr))
-		return sprintf(buf, "2\n");  /* thermistor */
+		return sprintf(buf, "4\n");  /* thermistor */
 	return sprintf(buf, "0\n");      /* disabled */
 }
 static ssize_t set_sensor(struct device *dev, struct device_attribute *attr,
@@ -493,10 +493,15 @@ static ssize_t set_sensor(struct device
 
 	data->sensor &= ~(1 << nr);
 	data->sensor &= ~(8 << nr);
-	/* 3 = thermal diode; 2 = thermistor; 0 = disabled */
+	if (val == 2) {	/* backwards compatibility */
+		dev_warn(dev, "Sensor type 2 is deprecated, please use 4 "
+			 "instead\n");
+		val = 4;
+	}
+	/* 3 = thermal diode; 4 = thermistor; 0 = disabled */
 	if (val == 3)
 	    data->sensor |= 1 << nr;
-	else if (val == 2)
+	else if (val == 4)
 	    data->sensor |= 8 << nr;
 	else if (val != 0) {
 		mutex_unlock(&data->update_lock);


-- 
Jean Delvare