[PATCH v4 05/10] hwmon: (tmp421) support specifying n-factor via DT
From: Krzysztof Adamski <hidden>
Date: 2021-10-12 09:28:15
Also in:
linux-hwmon
Subsystem:
hardware monitoring, the rest · Maintainers:
Guenter Roeck, Linus Torvalds
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 */ + + err = of_property_read_s32(child, "ti,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