linux-kernel - Re: [PATCH] power: supply: max1720x: add support for reading internal and thermistor temperatures

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Message-ID: <rvn4ixkj5ggjx4c3ip453nyltcjk6krzz5pjheqzsrxlikwswd@2t4jv6knrhn2>
Date: Wed, 15 Jan 2025 21:50:01 +0100
From: Sebastian Reichel <sebastian.reichel@...labora.com>
To: dimitri.fedrau@...bherr.com
Cc: linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Dimitri Fedrau <dima.fedrau@...il.com>, Thomas Antoine <t.antoine@...ouvain.be>
Subject: Re: [PATCH] power: supply: max1720x: add support for reading
 internal and thermistor temperatures

Hi,

On Mon, Jan 13, 2025 at 03:27:49PM +0100, Dimitri Fedrau via B4 Relay wrote:
> From: Dimitri Fedrau <dimitri.fedrau@...bherr.com>
> 
> If enabled in the nPackCfg register, the Temp1, Temp2 and IntTemp registers
> contain the temperature readings from the AIN1 thermistor, AIN2 thermistor
> and internal die temperature respectively. Registers are shared between SBS
> and normal IC functions and are always readable regardless of IC settings.
> 
> Signed-off-by: Dimitri Fedrau <dimitri.fedrau@...bherr.com>
> ---

Custom sysfs properties must be documented, see for example

Documentation/ABI/testing/sysfs-class-power-surface

Greetings,

-- Sebastian

>  drivers/power/supply/max1720x_battery.c | 60 ++++++++++++++++++++++++++++++++-
>  1 file changed, 59 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/power/supply/max1720x_battery.c b/drivers/power/supply/max1720x_battery.c
> index 9c7e14d2c7b87b8194511f36ade16e774281333e..e237528df29d2cac87361b75d71c576c0ed2b530 100644
> --- a/drivers/power/supply/max1720x_battery.c
> +++ b/drivers/power/supply/max1720x_battery.c
> @@ -16,6 +16,11 @@
>  
>  #include <linux/unaligned.h>
>  
> +/* SBS compliant registers */
> +#define MAX172XX_TEMP1			0x34
> +#define MAX172XX_INT_TEMP		0x35
> +#define MAX172XX_TEMP2			0x3B
> +
>  /* Nonvolatile registers */
>  #define MAX1720X_NXTABLE0		0x80
>  #define MAX1720X_NRSENSE		0xCF	/* RSense in 10^-5 Ohm */
> @@ -113,11 +118,15 @@ static const struct regmap_config max1720x_regmap_cfg = {
>  };
>  
>  static const struct regmap_range max1720x_nvmem_allow[] = {
> +	regmap_reg_range(MAX172XX_TEMP1, MAX172XX_INT_TEMP),
> +	regmap_reg_range(MAX172XX_TEMP2, MAX172XX_TEMP2),
>  	regmap_reg_range(MAX1720X_NXTABLE0, MAX1720X_NDEVICE_NAME4),
>  };
>  
>  static const struct regmap_range max1720x_nvmem_deny[] = {
> -	regmap_reg_range(0x00, 0x7F),
> +	regmap_reg_range(0x00, 0x33),
> +	regmap_reg_range(0x36, 0x3A),
> +	regmap_reg_range(0x3C, 0x7F),
>  	regmap_reg_range(0xE0, 0xFF),
>  };
>  
> @@ -388,6 +397,54 @@ static int max1720x_battery_get_property(struct power_supply *psy,
>  	return ret;
>  }
>  
> +static int max1720x_read_temp(struct device *dev, u8 reg, char *buf)
> +{
> +	struct power_supply *psy = dev_get_drvdata(dev);
> +	struct max1720x_device_info *info = power_supply_get_drvdata(psy);
> +	unsigned int val;
> +	int ret;
> +
> +	ret = regmap_read(info->regmap_nv, reg, &val);
> +	if (ret < 0)
> +		return ret;
> +
> +	/*
> +	 * Temperature in degrees Celsius starting at absolute zero, -273C or
> +	 * 0K with an LSb of 0.1C
> +	 */
> +	return sysfs_emit(buf, "%d\n", val - 2730);
> +}
> +
> +static
> +ssize_t temp1_show(struct device *dev, struct device_attribute *attr, char *buf)
> +{
> +	return max1720x_read_temp(dev, MAX172XX_TEMP1, buf);
> +}
> +
> +static
> +ssize_t temp2_show(struct device *dev, struct device_attribute *attr, char *buf)
> +{
> +	return max1720x_read_temp(dev, MAX172XX_TEMP2, buf);
> +}
> +
> +static
> +ssize_t int_temp_show(struct device *dev, struct device_attribute *attr, char *buf)
> +{
> +	return max1720x_read_temp(dev, MAX172XX_INT_TEMP, buf);
> +}
> +
> +static DEVICE_ATTR_RO(temp1);
> +static DEVICE_ATTR_RO(temp2);
> +static DEVICE_ATTR_RO(int_temp);
> +
> +static struct attribute *max1720x_attrs[] = {
> +	&dev_attr_temp1.attr,
> +	&dev_attr_temp2.attr,
> +	&dev_attr_int_temp.attr,
> +	NULL
> +};
> +ATTRIBUTE_GROUPS(max1720x);
> +
>  static
>  int max1720x_nvmem_reg_read(void *priv, unsigned int off, void *val, size_t len)
>  {
> @@ -488,6 +545,7 @@ static int max1720x_probe(struct i2c_client *client)
>  
>  	psy_cfg.drv_data = info;
>  	psy_cfg.fwnode = dev_fwnode(dev);
> +	psy_cfg.attr_grp = max1720x_groups;
>  	i2c_set_clientdata(client, info);
>  	info->regmap = devm_regmap_init_i2c(client, &max1720x_regmap_cfg);
>  	if (IS_ERR(info->regmap))
> 
> ---
> base-commit: a3a8799165ff83bb764fd800c6559c3cba0ddac3
> change-id: 20250113-max1720x-temperature-cec67fb40197
> 
> Best regards,
> -- 
> Dimitri Fedrau <dimitri.fedrau@...bherr.com>
> 
> 

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