[RFT PATCH] hwmon: (tmp401) Fix temperature register accesses for TMP461

[Guenter Roeck <linux@roeck-us.net>]

TMP461 does not support 16-bit registers. Use two 8-bit accesses to read
and write temperature values and limits for this chip.

Fixes: 24333ac26d01 ("hwmon: (tmp401) use smb word operations instead of 2 smb byte operations")
Reported-by: David T. Wilson <david.wilson@nasa.gov>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---
 drivers/hwmon/tmp401.c | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/drivers/hwmon/tmp401.c b/drivers/hwmon/tmp401.c
index 9dc210b55e69..78d50a9d26d7 100644
--- a/drivers/hwmon/tmp401.c
+++ b/drivers/hwmon/tmp401.c
@@ -69,6 +69,14 @@ static const u8 TMP401_TEMP_MSB_WRITE[7][2] = {
 	{ 0, 0x11 },	/* offset */
 };
 
+static const u8 TMP461_TEMP_LSB[5][2] = {
+	{ 0x15, 0x10 },	/* temp */
+	{ 0, 0x14 },	/* low limit (local n/a) */
+	{ 0, 0x13 },	/* high limit (local n/a) */
+	{ 0, 0 },	/* therm (crit) limit (n/a) */
+	{ 0, 0x12 },    /* offset (local n/a) */
+};
+
 static const u8 TMP432_TEMP_MSB_READ[4][3] = {
 	{ 0x00, 0x01, 0x23 },	/* temp */
 	{ 0x06, 0x08, 0x16 },	/* low limit */
@@ -190,6 +198,19 @@ static int tmp401_update_device_reg16(struct i2c_client *client,
 						TMP401_TEMP_MSB_READ[j][i];
 			if (j == 3) { /* crit is msb only */
 				val = i2c_smbus_read_byte_data(client, regaddr);
+			} else if (data->kind == tmp461) {
+				/* TMP461 does not support 16-bit registers */
+				val = i2c_smbus_read_byte_data(client, regaddr);
+				if (val < 0)
+					return val;
+				data->temp[j][i] = val << 8;
+				regaddr = TMP461_TEMP_LSB[j][i];
+				if (regaddr) {
+					val = i2c_smbus_read_byte_data(client, regaddr);
+					if (val < 0)
+						return val;
+					data->temp[j][i] |= val;
+				}
 			} else {
 				val = i2c_smbus_read_word_swapped(client,
 								  regaddr);
@@ -343,6 +364,12 @@ static ssize_t temp_store(struct device *dev,
 				       : TMP401_TEMP_MSB_WRITE[nr][index];
 	if (nr == 3) { /* crit is msb only */
 		i2c_smbus_write_byte_data(client, regaddr, reg >> 8);
+	} else if (data->kind == tmp461) {
+		/* TMP461 does not support 16-bit registers */
+		i2c_smbus_write_byte_data(client, regaddr, reg >> 8);
+		regaddr = TMP461_TEMP_LSB[nr][index];
+		if (regaddr)
+			i2c_smbus_write_byte_data(client, regaddr, reg & 0xFF);
 	} else {
 		/* Hardware expects big endian data --> use _swapped */
 		i2c_smbus_write_word_swapped(client, regaddr, reg);
-- 
2.33.0