Commit 3fba10dc authored by Krzysztof Adamski's avatar Krzysztof Adamski Committed by Guenter Roeck
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hwmon: (tmp421) support specifying n-factor via DT 



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: default avatarKrzysztof Adamski <krzysztof.adamski@nokia.com>
Link: https://lore.kernel.org/r/69d0bfcc5ba27c67f21d3eabfb100656a14c75b9.1634206677.git.krzysztof.adamski@nokia.com


Signed-off-by: default avatarGuenter Roeck <linux@roeck-us.net>
parent 45e9bda4

drivers/hwmon/tmp421.c

+18 −0
Original line number Diff line number Diff line
@@ -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;

}