[PATCH 1/2] thermal/drivers/mediatek/auxadc: Register per-sensor thermal zones

[Daniel Lezcano]

On 10/6/26 04:54, Nils Büchner wrote:
> The driver registers only thermal zone 0, which reports the hottest of
> all sensors. The MT8183 devicetree also describes a zone per sensor
> (soc, gpu, md1, cpu-little, cpu-big, abb as sensor ids 1-6), and
> mtk-svs looks up the "gpu-thermal" zone for its GPU banks. Without it
> SVS fails to probe on MT8183:
> 
>    SVSB_GPU: cannot get "gpu-thermal" thermal zone
>    mtk-svs 1100bc00.svs: error -ENODEV: svs bank resource setup fail
> 
> so the SoC never gets its calibrated, lower voltages.
> 
> Additionally register every sensor that has a devicetree zone, using
> sensor id = sensor number + 1, read from that sensor's own measurement
> register. Sensors without a zone are skipped, so SoCs whose devicetrees
> only describe zone 0 are unaffected.
> 
> Runtime-tested on an Acer Chromebook Spin 311 (MT8183, juniper) with a
> 7.0-based kernel (the hardware is not set up to boot mainline);
> build-tested on mainline with W=1. On the device: all six
> sensor zones register and read plausible values (31-34 C idle, close
> to the board sensors), and mtk-svs finds gpu-thermal.
> 
> The change and this changelog were drafted with an AI coding assistant
> during a debugging session on the hardware; they were reviewed and
> tested by the submitter.
> 
> Assisted-by: Claude Opus 5.5
> Signed-off-by: Nils Büchner <nils at buechner.me>
> ---
>   drivers/thermal/mediatek/auxadc_thermal.c | 80 ++++++++++++++++++++++-
>   1 file changed, 79 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/thermal/mediatek/auxadc_thermal.c b/drivers/thermal/mediatek/auxadc_thermal.c
> index 9ee2e7283..59c8eaf87 100644
> --- a/drivers/thermal/mediatek/auxadc_thermal.c
> +++ b/drivers/thermal/mediatek/auxadc_thermal.c
> @@ -308,6 +308,13 @@ struct mtk_thermal_bank {
>   	int id;
>   };
>   
> +/* A single sensor, exposed as its own thermal zone (DT sensor id = sensor + 1) */
> +struct mtk_thermal_sensor {
> +	struct mtk_thermal *mt;
> +	int bank;
> +	int index;
> +};
> +
>   struct mtk_thermal_data {
>   	s32 num_banks;
>   	s32 num_sensors;
> @@ -870,6 +877,77 @@ static const struct thermal_zone_device_ops mtk_thermal_ops = {
>   	.get_temp = mtk_read_temp,
>   };
>   
> +static int mtk_read_sensor_temp(struct thermal_zone_device *tz, int *temperature)
> +{
> +	struct mtk_thermal_sensor *sensor = thermal_zone_device_priv(tz);
> +	struct mtk_thermal *mt = sensor->mt;
> +	const struct mtk_thermal_data *conf = mt->conf;
> +	struct mtk_thermal_bank *bank = &mt->banks[sensor->bank];
> +	int temp;
> +	u32 raw;
> +
> +	mtk_thermal_get_bank(bank);
> +	raw = readl(mt->thermal_base + conf->msr[sensor->index]);
> +	temp = mt->raw_to_mcelsius(mt, conf->bank_data[sensor->bank].sensors[sensor->index],
> +				   raw);
> +	mtk_thermal_put_bank(bank);
> +
> +	if (!mtk_thermal_temp_is_valid(temp))
> +		return -EAGAIN;
> +
> +	*temperature = temp;
> +
> +	return 0;
> +}
> +
> +static const struct thermal_zone_device_ops mtk_thermal_sensor_ops = {
> +	.get_temp = mtk_read_sensor_temp,
> +};
> +
> +/*
> + * Zone 0 reports the hottest sensor. Also register every individual sensor
> + * the devicetree describes (sensor id = sensor number + 1): MT8183 SVS looks
> + * up its GPU bank temperature through the "gpu-thermal" zone and cannot
> + * probe without it. Sensors without a devicetree zone are skipped.
> + */
> +static int mtk_thermal_register_sensors(struct mtk_thermal *mt)
> +{
> +	const struct mtk_thermal_data *conf = mt->conf;
> +	struct thermal_zone_device *tzdev;
> +	struct mtk_thermal_sensor *sensor;
> +	int id, b, i;
> +
> +	for (id = 1; id <= conf->num_sensors; id++) {
> +		sensor = NULL;
> +		for (b = 0; b < conf->num_banks && !sensor; b++) {
> +			for (i = 0; i < conf->bank_data[b].num_sensors; i++) {
> +				if (conf->bank_data[b].sensors[i] != id - 1)
> +					continue;
> +				sensor = devm_kzalloc(mt->dev, sizeof(*sensor), GFP_KERNEL);
> +				if (!sensor)
> +					return -ENOMEM;
> +				sensor->mt = mt;
> +				sensor->bank = b;
> +				sensor->index = i;
> +				break;
> +			}
> +		}
> +		if (!sensor)
> +			continue;

Please move routines into self-explanatory functions and make this 
initialization function simpler to understand

> +
> +		tzdev = devm_thermal_of_zone_register(mt->dev, id, sensor,
> +						      &mtk_thermal_sensor_ops);
> +		if (IS_ERR(tzdev)) {
> +			if (PTR_ERR(tzdev) == -ENODEV)
> +				continue;
> +			return dev_err_probe(mt->dev, PTR_ERR(tzdev),
> +					     "failed to register sensor %d\n", id);
> +		}
> +	}
> +
> +	return 0;
> +}
> +
>   static void mtk_thermal_init_bank(struct mtk_thermal *mt, int num,
>   				  u32 apmixed_phys_base, u32 auxadc_phys_base,
>   				  int ctrl_id)
> @@ -1294,7 +1372,7 @@ static int mtk_thermal_probe(struct platform_device *pdev)
>   	if (ret)
>   		dev_warn(&pdev->dev, "error in thermal_add_hwmon_sysfs");
>   
> -	return 0;
> +	return mtk_thermal_register_sensors(mt);
>   }
>   
>   static struct platform_driver mtk_thermal_driver = {