Message-ID: <aWq7d5XOpeUYdlzg@lizhi-Precision-Tower-5810>
Date: Fri, 16 Jan 2026 17:28:07 -0500
From: Frank Li <Frank.li@....com>
To: Mayank Mahajan <mayankmahajan.x@....com>
Cc: linux@...ck-us.net, corbet@....net, robh@...nel.org, krzk+dt@...nel.org,
	conor+dt@...nel.org, linux-hwmon@...r.kernel.org,
	devicetree@...r.kernel.org, linux-doc@...r.kernel.org,
	linux-kernel@...r.kernel.org, priyanka.jain@....com,
	vikash.bansal@....com
Subject: Re: [PATCH v4 2/3] hwmon: (tmp108) Add support for P3T1035 and
 P3T2030

On Fri, Jan 16, 2026 at 05:05:53PM +0530, Mayank Mahajan wrote:
> Add support for the P3T1035 & P3T2030 temperature sensor. While mostly
> compatible with the TMP108, P3T1035 uses an 8-bit configuration register
> instead of the 16-bit layout used by TMP108. Updated driver to handle
> this difference during configuration read/write.
>
> Signed-off-by: Mayank Mahajan <mayankmahajan.x@....com>
> ---
> V1 -> V2:
> - Disabled hysteresis in is_visible function for P3T1035.
> - Added tables for conversion rate similar to the LM75 driver.
> - Implemented different bus access depending on the chip being used.
>    - Removed regmap for 8 bits; now we are using one regmap as before.
>    - Added read and write functions for i2c and i3c for use with regmap.
>    - Mapped the 8-bit configuration register to a 16 bit value for P3T1035.
> V2 -> V3:
> - Remove changes not relevant to adding a new device in the driver.
> - Address warnings due to incorrect usage of casting operations.
> - Remove the usage of P3T2030 as it's functionally identical to P3T1035.
> V3 -> V4:
> - Add GENMASK for getting mask for conversion rates.
> - Add static arrays for containing sample times for different sensors.
> - Remove redundant code such as checking for NULL pointer in probe.
> - Improve readability by removing double negation.
> - Remove type cast where not required; make reg_buf & val_buf local.
>
>  drivers/hwmon/Kconfig  |   2 +-
>  drivers/hwmon/tmp108.c | 203 +++++++++++++++++++++++++++++++++--------
>  2 files changed, 164 insertions(+), 41 deletions(-)
>
> diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
> index 157678b821fc..31969bddc812 100644
> --- a/drivers/hwmon/Kconfig
> +++ b/drivers/hwmon/Kconfig
> @@ -2398,7 +2398,7 @@ config SENSORS_TMP108
>  	select REGMAP_I3C if I3C
>  	help
>  	  If you say yes here you get support for Texas Instruments TMP108
> -	  sensor chips and NXP P3T1085.
> +	  sensor chips, NXP temperature sensors P3T1035, P3T1085 and P3T2030.
>
>  	  This driver can also be built as a module. If so, the module
>  	  will be called tmp108.
> diff --git a/drivers/hwmon/tmp108.c b/drivers/hwmon/tmp108.c
> index 60a237cbedbc..d308e2aed18a 100644
> --- a/drivers/hwmon/tmp108.c
> +++ b/drivers/hwmon/tmp108.c
> @@ -17,9 +17,16 @@
>  #include <linux/regmap.h>
>  #include <linux/regulator/consumer.h>
>  #include <linux/slab.h>
> +#include <linux/util_macros.h>
>
>  #define	DRIVER_NAME "tmp108"
>
> +enum tmp108_hw_id {
> +	P3T1035_ID,		/* For sensors p3t1035 and p3t2030 */
> +	P3T1085_ID,
> +	TMP108_ID,
> +};
> +
>  #define	TMP108_REG_TEMP		0x00
>  #define	TMP108_REG_CONF		0x01
>  #define	TMP108_REG_TLOW		0x02
> @@ -61,6 +68,7 @@
>  #define TMP108_CONVRATE_1HZ		TMP108_CONF_CR0		/* Default */
>  #define TMP108_CONVRATE_4HZ		TMP108_CONF_CR1
>  #define TMP108_CONVRATE_16HZ		(TMP108_CONF_CR0|TMP108_CONF_CR1)
> +#define TMP108_CONVRATE_SHIFT		13
>
>  #define TMP108_CONF_HYSTERESIS_MASK	(TMP108_CONF_HYS0|TMP108_CONF_HYS1)
>  #define TMP108_HYSTERESIS_0C		0x0000
> @@ -70,12 +78,23 @@
>
>  #define TMP108_CONVERSION_TIME_MS	30	/* in milli-seconds */
>
> +#define TMP108_CONF_CR0_POS		13
> +#define TMP108_CONF_CR1_POS		14
> +#define TMP108_CONF_CONVRATE_FLD	GENMASK(TMP108_CONF_CR1_POS, TMP108_CONF_CR0_POS)
> +
>  struct tmp108 {
> -	struct regmap *regmap;
> -	u16 orig_config;
> -	unsigned long ready_time;
> +	struct regmap		*regmap;
> +	u16			orig_config;
> +	unsigned long		ready_time;

don't mix format change in this patch.
Now prefer orignial format, just one space between type and field.

> +	enum tmp108_hw_id	hw_id;
> +	bool			config_reg_16bits;
> +	ushort			*sample_times;
> +	size_t			n_sample_times;
>  };
>
> +ushort p3t1035_sample_times[] = {4000, 1000, 250, 125};
> +ushort tmp108_sample_times[] = {4000, 1000, 250, 63};
> +
>  /* convert 12-bit TMP108 register value to milliCelsius */
>  static inline int tmp108_temp_reg_to_mC(s16 val)
>  {
> @@ -101,21 +120,7 @@ static int tmp108_read(struct device *dev, enum hwmon_sensor_types type,
>  					  &regval);
>  			if (err < 0)
>  				return err;
> -			switch (regval & TMP108_CONF_CONVRATE_MASK) {
> -			case TMP108_CONVRATE_0P25HZ:
> -			default:
> -				*temp = 4000;
> -				break;
> -			case TMP108_CONVRATE_1HZ:
> -				*temp = 1000;
> -				break;
> -			case TMP108_CONVRATE_4HZ:
> -				*temp = 250;
> -				break;
> -			case TMP108_CONVRATE_16HZ:
> -				*temp = 63;
> -				break;
> -			}
> +			*temp = tmp108->sample_times[FIELD_GET(TMP108_CONF_CONVRATE_FLD, regval)];

This code optimation need seperate patch.

>  			return 0;
>  		}
>  		return -EOPNOTSUPP;
> @@ -192,22 +197,17 @@ static int tmp108_write(struct device *dev, enum hwmon_sensor_types type,
>  {
>  	struct tmp108 *tmp108 = dev_get_drvdata(dev);
>  	u32 regval, mask;
> +	u8 index;
>  	int err;
>
>  	if (type == hwmon_chip) {
>  		if (attr == hwmon_chip_update_interval) {
> -			if (temp < 156)
> -				mask = TMP108_CONVRATE_16HZ;
> -			else if (temp < 625)
> -				mask = TMP108_CONVRATE_4HZ;
> -			else if (temp < 2500)
> -				mask = TMP108_CONVRATE_1HZ;
> -			else
> -				mask = TMP108_CONVRATE_0P25HZ;
> +			index = find_closest_descending(temp, tmp108->sample_times,
> +							tmp108->n_sample_times);

Need seperate patch for the code cleanup.

>  			return regmap_update_bits(tmp108->regmap,
>  						  TMP108_REG_CONF,
>  						  TMP108_CONF_CONVRATE_MASK,
> -						  mask);
> +						  FIELD_PREP(TMP108_CONF_CONVRATE_FLD, index));
>  		}
>  		return -EOPNOTSUPP;
>  	}
> @@ -251,6 +251,8 @@ static int tmp108_write(struct device *dev, enum hwmon_sensor_types type,
>  static umode_t tmp108_is_visible(const void *data, enum hwmon_sensor_types type,
>  				 u32 attr, int channel)
>  {
> +	const struct tmp108 *tmp108 = data;
> +
>  	if (type == hwmon_chip && attr == hwmon_chip_update_interval)
>  		return 0644;
>
> @@ -264,8 +266,11 @@ static umode_t tmp108_is_visible(const void *data, enum hwmon_sensor_types type,
>  		return 0444;
>  	case hwmon_temp_min:
>  	case hwmon_temp_max:
> +		return 0644;
>  	case hwmon_temp_min_hyst:
>  	case hwmon_temp_max_hyst:
> +		if (tmp108->hw_id == P3T1035_ID)
> +			return 0;
>  		return 0644;
>  	default:
>  		return 0;
> @@ -311,6 +316,106 @@ static bool tmp108_is_volatile_reg(struct device *dev, unsigned int reg)
>  	return reg == TMP108_REG_TEMP || reg == TMP108_REG_CONF;
>  }
>
> +static int tmp108_i2c_reg_read(void *context, unsigned int reg, unsigned int *val)
> +{
> +	struct i2c_client *client = context;
> +	struct tmp108 *tmp108 = i2c_get_clientdata(client);
> +	int ret;
> +
> +	if (reg == TMP108_REG_CONF && !tmp108->config_reg_16bits) {
> +		ret = i2c_smbus_read_byte_data(client, TMP108_REG_CONF);
> +		if (ret < 0)
> +			return ret;
> +		*val = ret << 8;
> +		return 0;
> +	}
> +
> +	ret = i2c_smbus_read_word_swapped(client, reg);
> +	if (ret < 0)
> +		return ret;
> +	*val = ret;
> +	return 0;
> +}
> +
> +static int tmp108_i2c_reg_write(void *context, unsigned int reg, unsigned int val)
> +{
> +	struct i2c_client *client = context;
> +	struct tmp108 *tmp108 = i2c_get_clientdata(client);
> +
> +	if (reg == TMP108_REG_CONF && !tmp108->config_reg_16bits)
> +		return i2c_smbus_write_byte_data(client, reg, val >> 8);
> +	return i2c_smbus_write_word_swapped(client, reg, val);
> +}
> +
> +static const struct regmap_bus tmp108_i2c_regmap_bus = {
> +	.reg_read = tmp108_i2c_reg_read,
> +	.reg_write = tmp108_i2c_reg_write,
> +};
> +
> +static int tmp108_i3c_reg_read(void *context, unsigned int reg, unsigned int *val)
> +{
> +	struct i3c_device *i3cdev = context;
> +	struct tmp108 *tmp108 = i3cdev_get_drvdata(i3cdev);
> +	u8 reg_buf[1], val_buf[2];
> +	struct i3c_xfer xfers[] = {
> +		{
> +			.rnw = false,
> +			.len = 1,
> +			.data.out = reg_buf,
> +		},
> +		{
> +			.rnw = true,
> +			.len = 2,
> +			.data.in = val_buf,
> +		},
> +	};
> +	int ret;
> +
> +	reg_buf[0] = reg;
> +
> +	if (reg == TMP108_REG_CONF && !tmp108->config_reg_16bits)
> +		xfers[1].len--;
> +
> +	ret = i3c_device_do_xfers(i3cdev, xfers, 2, I3C_SDR);
> +	if (ret < 0)
> +		return ret;
> +
> +	*val = val_buf[0] << 8;
> +	if (reg != TMP108_REG_CONF || tmp108->config_reg_16bits)
> +		*val |= val_buf[1];
> +
> +	return 0;
> +}
> +
> +static int tmp108_i3c_reg_write(void *context, unsigned int reg, unsigned int val)
> +{
> +	struct i3c_device *i3cdev = context;
> +	struct tmp108 *tmp108 = i3cdev_get_drvdata(i3cdev);
> +	u8 val_buf[3];
> +	struct i3c_xfer xfers[] = {
> +		{
> +			.rnw = false,
> +			.len = 3,
> +			.data.out = val_buf,
> +		},
> +	};
> +
> +	val_buf[0] = reg;
> +	val_buf[1] = (val >> 8) & 0xff;
> +
> +	if (reg == TMP108_REG_CONF && !tmp108->config_reg_16bits)
> +		xfers[0].len--;
> +	else
> +		val_buf[2] = val & 0xff;
> +
> +	return i3c_device_do_xfers(i3cdev, xfers, 1, I3C_SDR);
> +}
> +
> +static const struct regmap_bus tmp108_i3c_regmap_bus = {
> +	.reg_read = tmp108_i3c_reg_read,
> +	.reg_write = tmp108_i3c_reg_write,
> +};
> +
>  static const struct regmap_config tmp108_regmap_config = {
>  	.reg_bits = 8,
>  	.val_bits = 16,
> @@ -323,7 +428,8 @@ static const struct regmap_config tmp108_regmap_config = {
>  	.use_single_write = true,
>  };
>
> -static int tmp108_common_probe(struct device *dev, struct regmap *regmap, char *name)
> +static int tmp108_common_probe(struct device *dev, struct regmap *regmap, char *name,
> +			       enum tmp108_hw_id hw_id)
>  {
>  	struct device *hwmon_dev;
>  	struct tmp108 *tmp108;
> @@ -340,6 +446,15 @@ static int tmp108_common_probe(struct device *dev, struct regmap *regmap, char *
>
>  	dev_set_drvdata(dev, tmp108);
>  	tmp108->regmap = regmap;
> +	tmp108->hw_id = hw_id;
> +	tmp108->config_reg_16bits = (hw_id == P3T1035_ID) ? false : true;
> +	if (hw_id == P3T1035_ID) {
> +		tmp108->sample_times = p3t1035_sample_times;
> +		tmp108->n_sample_times = ARRAY_SIZE(p3t1035_sample_times);
> +	} else {
> +		tmp108->sample_times = tmp108_sample_times;
> +		tmp108->n_sample_times = ARRAY_SIZE(tmp108_sample_times);
> +	}
>
>  	err = regmap_read(tmp108->regmap, TMP108_REG_CONF, &config);
>  	if (err < 0) {
> @@ -351,7 +466,6 @@ static int tmp108_common_probe(struct device *dev, struct regmap *regmap, char *
>  	/* Only continuous mode is supported. */
>  	config &= ~TMP108_CONF_MODE_MASK;
>  	config |= TMP108_MODE_CONTINUOUS;
> -
>  	/* Only comparator mode is supported. */
>  	config &= ~TMP108_CONF_TM;
>
> @@ -384,17 +498,20 @@ static int tmp108_probe(struct i2c_client *client)
>  {
>  	struct device *dev = &client->dev;
>  	struct regmap *regmap;
> +	enum tmp108_hw_id hw_id;
>
>  	if (!i2c_check_functionality(client->adapter,
> -				     I2C_FUNC_SMBUS_WORD_DATA))
> +				     I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA))
>  		return dev_err_probe(dev, -ENODEV,
>  				     "adapter doesn't support SMBus word transactions\n");
>
> -	regmap = devm_regmap_init_i2c(client, &tmp108_regmap_config);
> +	regmap = devm_regmap_init(dev, &tmp108_i2c_regmap_bus, client, &tmp108_regmap_config);
>  	if (IS_ERR(regmap))
>  		return dev_err_probe(dev, PTR_ERR(regmap), "regmap init failed");
>
> -	return tmp108_common_probe(dev, regmap, client->name);
> +	hw_id = (unsigned long)i2c_get_match_data(client);
> +
> +	return tmp108_common_probe(dev, regmap, client->name, hw_id);
>  }
>
>  static int tmp108_suspend(struct device *dev)
> @@ -420,15 +537,17 @@ static int tmp108_resume(struct device *dev)
>  static DEFINE_SIMPLE_DEV_PM_OPS(tmp108_dev_pm_ops, tmp108_suspend, tmp108_resume);
>
>  static const struct i2c_device_id tmp108_i2c_ids[] = {
> -	{ "p3t1085" },
> -	{ "tmp108" },
> -	{ }
> +	{ "p3t1035", P3T1035_ID },
> +	{ "p3t1085", P3T1085_ID },
> +	{ "tmp108", TMP108_ID },
> +	{}
>  };
>  MODULE_DEVICE_TABLE(i2c, tmp108_i2c_ids);
>
>  static const struct of_device_id tmp108_of_ids[] = {
> -	{ .compatible = "nxp,p3t1085", },
> -	{ .compatible = "ti,tmp108", },
> +	{ .compatible = "nxp,p3t1035", .data = (void *)(uintptr_t)P3T1035_ID },
> +	{ .compatible = "nxp,p3t1085", .data = (void *)(uintptr_t)P3T1085_ID },
> +	{ .compatible = "ti,tmp108", .data = (void *)(uintptr_t)TMP108_ID },

Do not use device ID, define struct drvdata

	struct tmp108_drvdata
	{
		.samples = p3t1035_sample_times;
		.reg_width = 16,
		...
	}

Frank
>  	{}
>  };
>  MODULE_DEVICE_TABLE(of, tmp108_of_ids);
> @@ -444,7 +563,8 @@ static struct i2c_driver tmp108_driver = {
>  };
>
>  static const struct i3c_device_id p3t1085_i3c_ids[] = {
> -	I3C_DEVICE(0x011b, 0x1529, NULL),
> +	I3C_DEVICE(0x011B, 0x1529, (void *)P3T1085_ID),
> +	I3C_DEVICE(0x011B, 0x152B, (void *)P3T1035_ID),
>  	{}
>  };
>  MODULE_DEVICE_TABLE(i3c, p3t1085_i3c_ids);
> @@ -453,13 +573,16 @@ static int p3t1085_i3c_probe(struct i3c_device *i3cdev)
>  {
>  	struct device *dev = i3cdev_to_dev(i3cdev);
>  	struct regmap *regmap;
> +	const struct i3c_device_id *id;
>
> -	regmap = devm_regmap_init_i3c(i3cdev, &tmp108_regmap_config);
> +	regmap = devm_regmap_init(dev, &tmp108_i3c_regmap_bus, i3cdev, &tmp108_regmap_config);
>  	if (IS_ERR(regmap))
>  		return dev_err_probe(dev, PTR_ERR(regmap),
>  				     "Failed to register i3c regmap\n");
>
> -	return tmp108_common_probe(dev, regmap, "p3t1085_i3c");
> +	id = i3c_device_match_id(i3cdev, p3t1085_i3c_ids);
> +
> +	return tmp108_common_probe(dev, regmap, "p3t1085_i3c", (unsigned long)id->data);
>  }
>
>  static struct i3c_driver p3t1085_driver = {
> --
> 2.34.1

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