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@xxxxxxxxx>
---
drivers/hwmon/tmp421.c | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
diff --git a/drivers/hwmon/tmp421.c b/drivers/hwmon/tmp421.c
index 30b601c157fe..b32fd2b6ed07 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 +331,20 @@ static int tmp421_probe_child_from_dt(struct i2c_client *client,
data->channel[i].enabled = of_device_is_available(child);
+ if (i == 0)
+ return 0; /* input 0 is internal channel */
+
+ err = of_property_read_s32(child, "n-factor", &val);
+ if (!err) {
+ 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;
}
--
2.31.1
