[PATCH v3 2/2] hwmon: (tmp401) Add support of three advanced features

[Camel Guo <camel.guo@axis.com>]

tmp401 driver supports TMP401, TMP411 and TMP43X temperature sensors.
According to their datasheet:
- all of them support extended temperature range feature;
- TMP411 and TPM43X support n-factor correction feature;
- TMP43X support beta compensation feature.

In order to support setting them during bootup, this commit reads
ti,extended-range-enable, ti,n-factor and ti,beta-compensation and set
the corresponding registers during probing.

Signed-off-by: Camel Guo <camel.guo@axis.com>
---

Notes:
    v3:
    - Instead of u32, use s32 for ti,n-factor.
    
    v2: no change

 drivers/hwmon/tmp401.c | 44 +++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 43 insertions(+), 1 deletion(-)

diff --git a/drivers/hwmon/tmp401.c b/drivers/hwmon/tmp401.c
index b86d9df7105d..8f49da997367 100644
--- a/drivers/hwmon/tmp401.c
+++ b/drivers/hwmon/tmp401.c
@@ -41,6 +41,8 @@ enum chips { tmp401, tmp411, tmp431, tmp432, tmp435 };
 #define TMP401_STATUS				0x02
 #define TMP401_CONFIG				0x03
 #define TMP401_CONVERSION_RATE			0x04
+#define TMP4XX_N_FACTOR_REG			0x18
+#define TMP43X_BETA_RANGE			0x25
 #define TMP401_TEMP_CRIT_HYST			0x21
 #define TMP401_MANUFACTURER_ID_REG		0xFE
 #define TMP401_DEVICE_ID_REG			0xFF
@@ -543,6 +545,8 @@ static int tmp401_init_client(struct tmp401_data *data)
 	struct regmap *regmap = data->regmap;
 	u32 config, config_orig;
 	int ret;
+	u32 val = 0;
+	s32 nfactor = 0;
 
 	/* Set conversion rate to 2 Hz */
 	ret = regmap_write(regmap, TMP401_CONVERSION_RATE, 5);
@@ -557,10 +561,48 @@ static int tmp401_init_client(struct tmp401_data *data)
 	config_orig = config;
 	config &= ~TMP401_CONFIG_SHUTDOWN;
 
+	if (of_property_read_bool(data->client->dev.of_node, "ti,extended-range-enable")) {
+		/* Enable measurement over extended temperature range */
+		config |= TMP401_CONFIG_RANGE;
+	}
+
 	data->extended_range = !!(config & TMP401_CONFIG_RANGE);
 
-	if (config != config_orig)
+	if (config != config_orig) {
 		ret = regmap_write(regmap, TMP401_CONFIG, config);
+		if (ret < 0)
+			return ret;
+	}
+
+	ret = of_property_read_u32(data->client->dev.of_node, "ti,n-factor", &nfactor);
+	if (!ret) {
+		if (data->kind == tmp401) {
+			dev_err(&data->client->dev, "ti,tmp401 does not support n-factor correction\n");
+			return -EINVAL;
+		}
+		if (nfactor < -128 || nfactor > 127) {
+			dev_err(&data->client->dev, "n-factor is invalid (%d)\n", nfactor);
+			return -EINVAL;
+		}
+		ret = regmap_write(regmap, TMP4XX_N_FACTOR_REG, (unsigned int)nfactor);
+		if (ret < 0)
+			return ret;
+	}
+
+	ret = of_property_read_u32(data->client->dev.of_node, "ti,beta-compensation", &val);
+	if (!ret) {
+		if (data->kind == tmp401 || data->kind == tmp411) {
+			dev_err(&data->client->dev, "ti,tmp401 or ti,tmp411 does not support beta compensation\n");
+			return -EINVAL;
+		}
+		if (val > 15) {
+			dev_err(&data->client->dev, "beta-compensation is invalid (%u)\n", val);
+			return -EINVAL;
+		}
+		ret = regmap_write(regmap, TMP43X_BETA_RANGE, val);
+		if (ret < 0)
+			return ret;
+	}
 
 	return ret;
 }
-- 
2.30.2