diff options
| -rw-r--r-- | drivers/acpi/thermal.c | 41 |
1 files changed, 34 insertions, 7 deletions
diff --git a/drivers/acpi/thermal.c b/drivers/acpi/thermal.c index e8c143caf0fd..ddbb7c8f994d 100644 --- a/drivers/acpi/thermal.c +++ b/drivers/acpi/thermal.c @@ -192,6 +192,7 @@ struct acpi_thermal { struct acpi_handle_list devices; struct thermal_zone_device *thermal_zone; int tz_enabled; + int kelvin_offset; struct mutex lock; }; @@ -581,7 +582,7 @@ static void acpi_thermal_check(void *data) } /* sys I/F for generic thermal sysfs support */ -#define KELVIN_TO_MILLICELSIUS(t) (t * 100 - 273200) +#define KELVIN_TO_MILLICELSIUS(t, off) (((t) - (off)) * 100) static int thermal_get_temp(struct thermal_zone_device *thermal, unsigned long *temp) @@ -596,7 +597,7 @@ static int thermal_get_temp(struct thermal_zone_device *thermal, if (result) return result; - *temp = KELVIN_TO_MILLICELSIUS(tz->temperature); + *temp = KELVIN_TO_MILLICELSIUS(tz->temperature, tz->kelvin_offset); return 0; } @@ -702,7 +703,8 @@ static int thermal_get_trip_temp(struct thermal_zone_device *thermal, if (tz->trips.critical.flags.valid) { if (!trip) { *temp = KELVIN_TO_MILLICELSIUS( - tz->trips.critical.temperature); + tz->trips.critical.temperature, + tz->kelvin_offset); return 0; } trip--; @@ -711,7 +713,8 @@ static int thermal_get_trip_temp(struct thermal_zone_device *thermal, if (tz->trips.hot.flags.valid) { if (!trip) { *temp = KELVIN_TO_MILLICELSIUS( - tz->trips.hot.temperature); + tz->trips.hot.temperature, + tz->kelvin_offset); return 0; } trip--; @@ -720,7 +723,8 @@ static int thermal_get_trip_temp(struct thermal_zone_device *thermal, if (tz->trips.passive.flags.valid) { if (!trip) { *temp = KELVIN_TO_MILLICELSIUS( - tz->trips.passive.temperature); + tz->trips.passive.temperature, + tz->kelvin_offset); return 0; } trip--; @@ -730,7 +734,8 @@ static int thermal_get_trip_temp(struct thermal_zone_device *thermal, tz->trips.active[i].flags.valid; i++) { if (!trip) { *temp = KELVIN_TO_MILLICELSIUS( - tz->trips.active[i].temperature); + tz->trips.active[i].temperature, + tz->kelvin_offset); return 0; } trip--; @@ -745,7 +750,8 @@ static int thermal_get_crit_temp(struct thermal_zone_device *thermal, if (tz->trips.critical.flags.valid) { *temperature = KELVIN_TO_MILLICELSIUS( - tz->trips.critical.temperature); + tz->trips.critical.temperature, + tz->kelvin_offset); return 0; } else return -EINVAL; @@ -1334,6 +1340,25 @@ static int acpi_thermal_get_info(struct acpi_thermal *tz) return 0; } +/* + * The exact offset between Kelvin and degree Celsius is 273.15. However ACPI + * handles temperature values with a single decimal place. As a consequence, + * some implementations use an offset of 273.1 and others use an offset of + * 273.2. Try to find out which one is being used, to present the most + * accurate and visually appealing number. + * + * The heuristic below should work for all ACPI thermal zones which have a + * critical trip point with a value being a multiple of 0.5 degree Celsius. + */ +static void acpi_thermal_guess_offset(struct acpi_thermal *tz) +{ + if (tz->trips.critical.flags.valid && + (tz->trips.critical.temperature % 5) == 1) + tz->kelvin_offset = 2731; + else + tz->kelvin_offset = 2732; +} + static int acpi_thermal_add(struct acpi_device *device) { int result = 0; @@ -1360,6 +1385,8 @@ static int acpi_thermal_add(struct acpi_device *device) if (result) goto free_memory; + acpi_thermal_guess_offset(tz); + result = acpi_thermal_register_thermal_zone(tz); if (result) goto free_memory; |