Re: [PATCH v4 05/10] hwmon: (tmp421) support specifying n-factor via DT
From: Guenter Roeck <linux@roeck-us.net>
Date: 2021-10-12 14:34:55
Also in:
linux-hwmon
On 10/12/21 2:28 AM, Krzysztof Adamski wrote:
quoted hunk ↗ jump to hunk
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 <redacted> --- drivers/hwmon/tmp421.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+)diff --git a/drivers/hwmon/tmp421.c b/drivers/hwmon/tmp421.c index fffffd671e34..fcd2932a6ddb 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 */ +
I think that should generate an error, ie
+ err = of_property_read_s32(child, "ti,n-factor", &val);
+ if (!err) {if (!i) 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;
}