Re: [PATCH v5 4/9] hwmon: (tmp421) support specifying n-factor via DT

[Guenter Roeck <linux@roeck-us.net>]

On Thu, Oct 14, 2021 at 03:01:28PM +0200, Krzysztof Adamski wrote:
> Previous patches added a way to specify some channel specific parameters
> in DT and n-factor is definitely one of them. This calibration mechanism
> is board specific as its value depends on the diodes/transistors being
> connected to the sensor and thus the DT seems like a right fit for that
> information. It is very similar to the value of shunt resistor that some
> drivers allows specifying in DT.
> 
> This patch adds a possibility to set n-factor for each channel via
> "n-factor" DT property in each channel subnode.
> 
> Signed-off-by: Krzysztof Adamski <krzysztof.adamski@nokia.com>

Applied, after "s/^  / /"

Guenter

> ---
>  drivers/hwmon/tmp421.c | 18 ++++++++++++++++++
>  1 file changed, 18 insertions(+)
> 
> diff --git a/drivers/hwmon/tmp421.c b/drivers/hwmon/tmp421.c
> index af08bc985a13..606914f20910 100644
> --- a/drivers/hwmon/tmp421.c
> +++ b/drivers/hwmon/tmp421.c
> @@ -34,6 +34,7 @@ enum chips { tmp421, tmp422, tmp423, tmp441, tmp442 };
>  #define TMP421_STATUS_REG			0x08
>  #define TMP421_CONFIG_REG_1			0x09
>  #define TMP421_CONVERSION_RATE_REG		0x0B
> +#define TMP421_N_FACTOR_REG_1			0x21
>  #define TMP421_MANUFACTURER_ID_REG		0xFE
>  #define TMP421_DEVICE_ID_REG			0xFF
>  
> @@ -310,6 +311,7 @@ static int tmp421_probe_child_from_dt(struct i2c_client *client,
>  {
>  	struct device *dev = &client->dev;
>  	u32 i;
> +	s32 val;
>  	int err;
>  
>  	err = of_property_read_u32(child, "reg", &i);
> @@ -329,6 +331,22 @@ static int tmp421_probe_child_from_dt(struct i2c_client *client,
>  
>  	data->channel[i].enabled = of_device_is_available(child);
>  
> +	err = of_property_read_s32(child, "ti,n-factor", &val);
> +	if (!err) {
> +		if (i == 0) {
> +			dev_err(dev, "n-factor can't be set for internal channel\n");
> +			return -EINVAL;
> +		}
> +
> +		if (val > 127 || val < -128) {
> +			dev_err(dev, "n-factor for channel %d invalid (%d)\n",
> +				i, val);
> +			return -EINVAL;
> +		}
> +		i2c_smbus_write_byte_data(client, TMP421_N_FACTOR_REG_1 + i - 1,
> +						  val);
> +	}
> +
>  	return 0;
>  }
>