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thermal: kirkwood: Fix thermal sensor formula

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The currently formula has been taken from the 88AP510 SoC datasheet,
which is not exactly correct. The correct value for the temperature
in Celcius of the sensor present in this SoC is:

  Celsius = (322-reg)/1.3625

Signed-off-by: Lior Amsalem <alior@marvell.com>
Signed-off-by: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
Acked-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>
This commit is contained in:
Ezequiel Garcia 2013-03-22 09:23:02 -03:00 committed by Zhang Rui
parent 02519d3397
commit 696b6075af
1 changed files with 4 additions and 4 deletions
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8
drivers/thermal/kirkwood_thermal.c
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@ -49,13 +49,13 @@ static int kirkwood_get_temp(struct thermal_zone_device *thermal,
}
/*
* Calculate temperature. See Section 8.10.1 of the 88AP510,
* datasheet, which has the same sensor.
* Documentation/arm/Marvell/README
* Calculate temperature. According to Marvell internal
* documentation the formula for this is:
* Celsius = (322-reg)/1.3625
*/
reg = (reg >> KIRKWOOD_THERMAL_TEMP_OFFSET) &
KIRKWOOD_THERMAL_TEMP_MASK;
*temp = ((2281638UL - (7298*reg)) / 10);
*temp = ((3220000000UL - (10000000UL * reg)) / 13625);
return 0;
}