Commit 47cbb046 authored by AngeloGioacchino Del Regno's avatar AngeloGioacchino Del Regno Committed by Daniel Lezcano
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thermal/drivers/mediatek: Add temperature constraints to validate read 



The AUXADC thermal v1 allows reading temperature range between -20°C to
150°C and any value out of this range is invalid.

Add new definitions for MT8173_TEMP_{MIN_MAX} and a new small helper
mtk_thermal_temp_is_valid() to check if new readings are in range: if
not, we tell to the API that the reading is invalid by returning
THERMAL_TEMP_INVALID.

It was chosen to introduce the helper function because, even though this
temperature range is realistically ok for all, it comes from a downstream
kernel driver for version 1, but here we also support v2 and v3 which may
may have wider constraints.

Signed-off-by: default avatarAngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: default avatarDaniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20230419061146.22246-3-angelogioacchino.delregno@collabora.com
parent 0a677eea

drivers/thermal/mediatek/auxadc_thermal.c

+18 −6
Original line number Diff line number Diff line
@@ -116,6 +116,10 @@ 
/* The calibration coefficient of sensor  */

#define MT8173_CALIBRATION	165



/* Valid temperatures range */

#define MT8173_TEMP_MIN		-20000

#define MT8173_TEMP_MAX		150000



/*

 * Layout of the fuses providing the calibration data

 * These macros could be used for MT8183, MT8173, MT2701, and MT2712.
@@ -689,6 +693,11 @@ static const struct mtk_thermal_data mt7986_thermal_data = { 
	.version = MTK_THERMAL_V3,

};



static bool mtk_thermal_temp_is_valid(int temp)

{

	return (temp >= MT8173_TEMP_MIN) && (temp <= MT8173_TEMP_MAX);

}



/**

 * raw_to_mcelsius_v1 - convert a raw ADC value to mcelsius

 * @mt:	The thermal controller
@@ -815,14 +824,17 @@ static int mtk_thermal_bank_temperature(struct mtk_thermal_bank *bank) 
		temp = mt->raw_to_mcelsius(

			mt, conf->bank_data[bank->id].sensors[i], raw);





		/*

		 * The first read of a sensor often contains very high bogus

		 * temperature value. Filter these out so that the system does

		 * not immediately shut down.

		 * Depending on the filt/sen intervals and ADC polling time,

		 * we may need up to 60 milliseconds after initialization: this

		 * will result in the first reading containing an out of range

		 * temperature value.

		 * Validate the reading to both address the aforementioned issue

		 * and to eventually avoid bogus readings during runtime in the

		 * event that the AUXADC gets unstable due to high EMI, etc.

		 */

		if (temp > 200000)

			temp = 0;

		if (!mtk_thermal_temp_is_valid(temp))

			temp = THERMAL_TEMP_INVALID;



		if (temp > max)

			max = temp;