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Subject: Re: [v7,3/3] thermal: mediatek: add another get_temp ops for thermal
 sensors
To:     Michael Kao <michael.kao@mediatek.com>, fan.chen@mediatek.com,
        Zhang Rui <rui.zhang@intel.com>, linux-pm@vger.kernel.org,
        srv_heupstream@mediatek.com
Cc:     Eduardo Valentin <edubezval@gmail.com>,
        Rob Herring <robh+dt@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Matthias Brugger <matthias.bgg@gmail.com>, hsinyi@chromium.org,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org,
        linux-mediatek@lists.infradead.org
References: <20210316070144.28440-1-michael.kao@mediatek.com>
 <20210316070144.28440-4-michael.kao@mediatek.com>
From:   Daniel Lezcano <daniel.lezcano@linaro.org>
Message-ID: <dac1f9bc-6caa-9cb7-97d6-882a8bd20fea@linaro.org>
Date:   Fri, 9 Apr 2021 10:16:04 +0200
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On 16/03/2021 08:01, Michael Kao wrote:
> Provide thermal zone to read thermal sensor
> in the SoC. We can read all the thermal sensors
> value in the SoC by the node /sys/class/thermal/
> 
> In mtk_thermal_bank_temperature, return -EAGAIN instead of -EACCESS
> on the first read of sensor that often are bogus values.
> This can avoid following warning on boot:
> 
>   thermal thermal_zone6: failed to read out thermal zone (-13)

This patch is changing more things than described in the changelog.

Is it possible to share some technical details about how the sensor(s)
are working or point to some documentation if any ? and possibly the
layout ?

IIUC there is a fake thermal zone zero with the purpose of aggregating
all the other sensors by taking the max temperature of all the sensors.

This patch adds a thermal zone per sensor, and each sensor is per CPU.
CPU0 being actually the max of all the other sensors, right ?


> Signed-off-by: Michael Kao <michael.kao@mediatek.com>
> Signed-off-by: Hsin-Yi Wang <hsinyi@chromium.org>
> ---
>  drivers/thermal/mtk_thermal.c | 100 +++++++++++++++++++++++++---------
>  1 file changed, 75 insertions(+), 25 deletions(-)
> 
> diff --git a/drivers/thermal/mtk_thermal.c b/drivers/thermal/mtk_thermal.c
> index 149c6d7fd5a0..57e4f08a947e 100644
> --- a/drivers/thermal/mtk_thermal.c
> +++ b/drivers/thermal/mtk_thermal.c
> @@ -245,6 +245,11 @@ enum mtk_thermal_version {
>  
>  struct mtk_thermal;
>  
> +struct mtk_thermal_zone {
> +	struct mtk_thermal *mt;
> +	int id;
> +};
> +
>  struct thermal_bank_cfg {
>  	unsigned int num_sensors;
>  	const int *sensors;
> @@ -637,6 +642,30 @@ static void mtk_thermal_put_bank(struct mtk_thermal_bank *bank)
>  		mutex_unlock(&mt->lock);
>  }
>  
> +static u32 _get_sensor_temp(struct mtk_thermal *mt, int id)
> +{
> +	u32 raw;
> +	int temp;
> +
> +	raw = readl(mt->thermal_base + mt->conf->msr[id]);
> +
> +	if (mt->conf->version == MTK_THERMAL_V1)
> +		temp = raw_to_mcelsius_v1(mt, id, raw);
> +	else
> +		temp = raw_to_mcelsius_v2(mt, id, 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.
> +	 */
> +
> +	if (temp > 200000)
> +		return -EAGAIN;
> +	else
> +		return temp;
> +}
> +
>  /**
>   * mtk_thermal_bank_temperature - get the temperature of a bank
>   * @bank:	The bank
> @@ -647,28 +676,11 @@ static void mtk_thermal_put_bank(struct mtk_thermal_bank *bank)
>  static int mtk_thermal_bank_temperature(struct mtk_thermal_bank *bank)
>  {
>  	struct mtk_thermal *mt = bank->mt;
> -	const struct mtk_thermal_data *conf = mt->conf;
>  	int i, temp = INT_MIN, max = INT_MIN;
> -	u32 raw;
> -
> -	for (i = 0; i < conf->bank_data[bank->id].num_sensors; i++) {
> -		raw = readl(mt->thermal_base + conf->msr[i]);
>  
> -		if (mt->conf->version == MTK_THERMAL_V1) {
> -			temp = raw_to_mcelsius_v1(
> -				mt, conf->bank_data[bank->id].sensors[i], raw);
> -		} else {
> -			temp = raw_to_mcelsius_v2(
> -				mt, conf->bank_data[bank->id].sensors[i], raw);
> -		}
> +	for (i = 0; i < mt->conf->bank_data[bank->id].num_sensors; i++) {
>  
> -		/*
> -		 * 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.
> -		 */
> -		if (temp > 200000)
> -			temp = 0;
> +		temp = _get_sensor_temp(mt, i);
>  
>  		if (temp > max)
>  			max = temp;
> @@ -679,7 +691,8 @@ static int mtk_thermal_bank_temperature(struct mtk_thermal_bank *bank)
>  
>  static int mtk_read_temp(void *data, int *temperature)
>  {
> -	struct mtk_thermal *mt = data;
> +	struct mtk_thermal_zone *tz = data;
> +	struct mtk_thermal *mt = tz->mt;
>  	int i;
>  	int tempmax = INT_MIN;
>  
> @@ -698,10 +711,28 @@ static int mtk_read_temp(void *data, int *temperature)
>  	return 0;
>  }
>  
> +static int mtk_read_sensor_temp(void *data, int *temperature)
> +{
> +	struct mtk_thermal_zone *tz = data;
> +	struct mtk_thermal *mt = tz->mt;
> +	int id = tz->id - 1;
> +
> +	if (id < 0)
> +		return -EACCES;
> +
> +	*temperature = _get_sensor_temp(mt, id);
> +
> +	return 0;
> +}
> +
>  static const struct thermal_zone_of_device_ops mtk_thermal_ops = {
>  	.get_temp = mtk_read_temp,
>  };
>  
> +static const struct thermal_zone_of_device_ops mtk_thermal_sensor_ops = {
> +	.get_temp = mtk_read_sensor_temp,
> +};
> +
>  static void mtk_thermal_init_bank(struct mtk_thermal *mt, int num,
>  				  u32 apmixed_phys_base, u32 auxadc_phys_base,
>  				  int ctrl_id)
> @@ -992,6 +1023,7 @@ static int mtk_thermal_probe(struct platform_device *pdev)
>  	u64 auxadc_phys_base, apmixed_phys_base;
>  	struct thermal_zone_device *tzdev;
>  	void __iomem *apmixed_base, *auxadc_base;
> +	struct mtk_thermal_zone *tz;
>  
>  	mt = devm_kzalloc(&pdev->dev, sizeof(*mt), GFP_KERNEL);
>  	if (!mt)
> @@ -1080,11 +1112,29 @@ static int mtk_thermal_probe(struct platform_device *pdev)
>  
>  	platform_set_drvdata(pdev, mt);
>  
> -	tzdev = devm_thermal_zone_of_sensor_register(&pdev->dev, 0, mt,
> -						     &mtk_thermal_ops);
> -	if (IS_ERR(tzdev)) {
> -		ret = PTR_ERR(tzdev);
> -		goto err_disable_clk_peri_therm;
> +	for (i = 0; i < mt->conf->num_sensors + 1; i++) {
> +		tz = devm_kmalloc(&pdev->dev, sizeof(*tz), GFP_KERNEL);
> +		if (!tz)
> +			return -ENOMEM;
> +
> +		tz->mt = mt;
> +		tz->id = i;
> +
> +		tzdev = devm_thermal_zone_of_sensor_register(&pdev->dev, i, tz, (i == 0) ?
> +							     &mtk_thermal_ops :
> +							     &mtk_thermal_sensor_ops);
> +
> +		if (IS_ERR(tzdev)) {
> +			if (PTR_ERR(tzdev) == -ENODEV) {
> +				dev_warn(&pdev->dev,
> +					 "sensor %d not registered in thermal zone in dt\n", i);
> +				continue;
> +			}
> +			if (PTR_ERR(tzdev) == -EACCES) {
> +				ret = PTR_ERR(tzdev);
> +				goto err_disable_clk_peri_therm;
> +			}
> +		}
>  	}
>  
>  	return 0;
> 


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