W1: w1_therm.c standardize units to millidegrees C
authorDavid Fries <david@fries.net>
Wed, 6 Feb 2008 09:38:09 +0000 (01:38 -0800)
committerLinus Torvalds <torvalds@woody.linux-foundation.org>
Wed, 6 Feb 2008 18:41:10 +0000 (10:41 -0800)
Standardize the temperature units to millidegrees C for the two sensor
conversion routines.  Previously the routines were,

w1_DS18B20_convert_temp degrees C
w1_DS18S20_convert_temp millidegrees C

Unfortunately this will break any program using the ds18b20 value as it
will now be 1000 times bigger.  Fortunately there can't be that many users
out there, or some of these bugs will have been fixed by now, such as the
negative C error (see previous patch) that makes me think the ds18b20 is
the better choice to change because of the current bugs.

Signed-off-by: David Fries <david@fries.net>
Cc: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
drivers/w1/slaves/w1_therm.c

index 112f4ec..fb28aca 100644 (file)
@@ -92,6 +92,7 @@ struct w1_therm_family_converter
        int                     (*convert)(u8 rom[9]);
 };
 
+/* The return value is millidegrees Centigrade. */
 static inline int w1_DS18B20_convert_temp(u8 rom[9]);
 static inline int w1_DS18S20_convert_temp(u8 rom[9]);
 
@@ -113,7 +114,7 @@ static struct w1_therm_family_converter w1_therm_families[] = {
 static inline int w1_DS18B20_convert_temp(u8 rom[9])
 {
        s16 t = (rom[1] << 8) | rom[0];
-       t /= 16;
+       t = t*1000/16;
        return t;
 }