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hwmon: (tmp421) support specifying n-factor via DT

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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>
Link: https://lore.kernel.org/r/69d0bfcc5ba27c67f21d3eabfb100656a14c75b9.1634206677.git.krzysztof.adamski@nokia.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
This commit is contained in:
Krzysztof Adamski 2021-10-14 15:01:28 +02:00 committed by Guenter Roeck
parent 45e9bda4ff
commit 3fba10dc03
1 changed files with 18 additions and 0 deletions
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18
drivers/hwmon/tmp421.c
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@ -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;
}