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thermal: dove: 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>
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Ezequiel Garcia authored and Zhang Rui committed Mar 26, 2013
1 parent 696b607 commit 2fd1db8
Showing 1 changed file with 4 additions and 3 deletions.
7 changes: 4 additions & 3 deletions drivers/thermal/dove_thermal.c
Original file line number Diff line number Diff line change
Expand Up @@ -107,12 +107,13 @@ static int dove_get_temp(struct thermal_zone_device *thermal,
}

/*
* Calculate temperature. See Section 8.10.1 of 88AP510,
* Documentation/arm/Marvell/README
* Calculate temperature. According to Marvell internal
* documentation the formula for this is:
* Celsius = (322-reg)/1.3625
*/
reg = readl_relaxed(priv->sensor);
reg = (reg >> DOVE_THERMAL_TEMP_OFFSET) & DOVE_THERMAL_TEMP_MASK;
*temp = ((2281638UL - (7298*reg)) / 10);
*temp = ((3220000000UL - (10000000UL * reg)) / 13625);

return 0;
}
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