[PATCH v1] hwmon: (lm75) Add support for Nuvoton NCT7715

[hsyemail2@gmail.com]

From: Sheng-Yuan Huang <syhuang3@nuvoton.com>

The Nuvoton NCT7715 is compatible with the LM75 temperature and
limit register layout, but its 16-bit configuration register is
transmitted most-significant byte first. Add support for the NCT7715,
including byte-swapped SMBus accesses for its configuration register.

Handle its conversion-rate field and shutdown bit separately, since
their bit positions differ from the standard LM75 layout.

Signed-off-by: Sheng-Yuan Huang <syhuang3@nuvoton.com>
---
 .../devicetree/bindings/hwmon/lm75.yaml       |  1 +
 Documentation/hwmon/lm75.rst                  |  6 ++
 drivers/hwmon/lm75.c                          | 57 ++++++++++++++++++-
 3 files changed, 62 insertions(+), 2 deletions(-)

diff --git a/Documentation/devicetree/bindings/hwmon/lm75.yaml b/Documentation/devicetree/bindings/hwmon/lm75.yaml
index b48bf3fd721f..832a8c5d83e9 100644
--- a/Documentation/devicetree/bindings/hwmon/lm75.yaml
+++ b/Documentation/devicetree/bindings/hwmon/lm75.yaml
@@ -31,6 +31,7 @@ properties:
       - nxp,p3t1750
       - nxp,p3t1755
       - nxp,pct2075
+      - nuvoton,nct7715
       - st,stds75
       - st,stlm75
       - microchip,tcn75
diff --git a/Documentation/hwmon/lm75.rst b/Documentation/hwmon/lm75.rst
index ca46754e028b..fac0b8f29ddc 100644
--- a/Documentation/hwmon/lm75.rst
+++ b/Documentation/hwmon/lm75.rst
@@ -150,6 +150,12 @@ Supported chips:
 
                https://ams.com/documents/20143/36005/AS6200_DS000449_4-00.pdf
 
+  * Nuvoton NCT7715
+
+    Prefix: 'nct7715'
+
+    Addresses scanned: none
+
 Author: Frodo Looijaard <frodol@dds.nl>
 
 Description
diff --git a/drivers/hwmon/lm75.c b/drivers/hwmon/lm75.c
index 2d2d752aeac9..0b55f6b7c68d 100644
--- a/drivers/hwmon/lm75.c
+++ b/drivers/hwmon/lm75.c
@@ -39,6 +39,7 @@ enum lm75_type {		/* keep sorted in alphabetical order */
 	max6626,
 	max31725,
 	mcp980x,
+	nct7715,
 	p3t1750,
 	p3t1755,
 	pct2075,
@@ -107,6 +108,15 @@ static const unsigned short normal_i2c[] = { 0x48, 0x49, 0x4a, 0x4b, 0x4c,
 #define LM75_REG_MAX		0x03
 #define PCT2075_REG_IDLE	0x04
 
+#define NCT7715_CONFIG_RESOLUTION_12_BIT	GENMASK(14, 13)
+#define NCT7715_CONFIG_SHUTDOWN			BIT(8)
+#define NCT7715_CONFIG_CONVERSION_RATE_MASK	GENMASK(7, 6)
+#define NCT7715_CONFIG_EXTENDED_MODE		BIT(4)
+#define NCT7715_CONFIG_RATE_0_25HZ		0
+#define NCT7715_CONFIG_RATE_1HZ			BIT(6)
+#define NCT7715_CONFIG_RATE_4HZ			BIT(7)
+#define NCT7715_CONFIG_RATE_8HZ			GENMASK(7, 6)
+
 struct lm75_data {
 	const char *label;
 	struct regmap			*regmap;
@@ -122,6 +132,10 @@ struct lm75_data {
 /*-----------------------------------------------------------------------*/
 
 static const u8 lm75_sample_set_masks[] = { 0 << 5, 1 << 5, 2 << 5, 3 << 5 };
+static const u16 nct7715_sample_set_masks[] = {
+	NCT7715_CONFIG_RATE_8HZ, NCT7715_CONFIG_RATE_4HZ,
+	NCT7715_CONFIG_RATE_1HZ, NCT7715_CONFIG_RATE_0_25HZ
+};
 
 #define LM75_ALERT_POLARITY_HIGH_8_BIT	(BIT(2))
 #define LM75_ALERT_POLARITY_HIGH_16_BIT	(BIT(2) << 8)
@@ -259,6 +273,15 @@ static const struct lm75_params device_params[] = {
 		.sample_times = (unsigned int []){ 30, 60, 120, 240 },
 		.resolutions = (u8 []) {9, 10, 11, 12 },
 	},
+	[nct7715] = {
+		.config_reg_16bits = true,
+		.set_mask = NCT7715_CONFIG_RESOLUTION_12_BIT,
+		.clr_mask = NCT7715_CONFIG_EXTENDED_MODE,
+		.default_resolution = 12,
+		.default_sample_time = 250,
+		.num_sample_times = 4,
+		.sample_times = (unsigned int []){ 125, 250, 1000, 4000 },
+	},
 	[tmp100] = {
 		.set_mask = 3 << 5,	/* 12-bit mode */
 		.clr_mask = 1 << 7,	/* not one-shot mode */
@@ -354,6 +377,11 @@ static inline long lm75_reg_to_mc(s16 temp, u8 resolution)
 static inline int lm75_write_config(struct lm75_data *data, u16 set_mask,
 				    u16 clr_mask)
 {
+	if (data->kind == nct7715)
+		return regmap_update_bits(data->regmap, LM75_REG_CONF,
+					  clr_mask | set_mask | NCT7715_CONFIG_SHUTDOWN,
+					  set_mask);
+
 	return regmap_update_bits(data->regmap, LM75_REG_CONF,
 				  clr_mask | set_mask | LM75_SHUTDOWN, set_mask);
 }
@@ -486,6 +514,13 @@ static int lm75_update_interval(struct device *dev, long val)
 		if (data->params->resolutions)
 			data->resolution = data->params->resolutions[index];
 		break;
+	case nct7715:
+		err = lm75_write_config(data, nct7715_sample_set_masks[index],
+					NCT7715_CONFIG_CONVERSION_RATE_MASK);
+		if (err)
+			return err;
+		data->sample_time = data->params->sample_times[index];
+		break;
 	case tmp112:
 	case as6200:
 		err = regmap_update_bits(data->regmap, LM75_REG_CONF,
@@ -609,6 +644,8 @@ static int lm75_i2c_reg_read(void *context, unsigned int reg, unsigned int *val)
 	if (reg == LM75_REG_CONF) {
 		if (!data->params->config_reg_16bits)
 			ret = i2c_smbus_read_byte_data(client, LM75_REG_CONF);
+		else if (data->kind == nct7715)
+			ret = i2c_smbus_read_word_swapped(client, LM75_REG_CONF);
 		else
 			ret = i2c_smbus_read_word_data(client, LM75_REG_CONF);
 	} else {
@@ -628,8 +665,11 @@ static int lm75_i2c_reg_write(void *context, unsigned int reg, unsigned int val)
 	if (reg == PCT2075_REG_IDLE ||
 	    (reg == LM75_REG_CONF && !data->params->config_reg_16bits))
 		return i2c_smbus_write_byte_data(client, reg, val);
-	else if (reg == LM75_REG_CONF)
+	else if (reg == LM75_REG_CONF) {
+		if (data->kind == nct7715)
+			return i2c_smbus_write_word_swapped(client, reg, val);
 		return i2c_smbus_write_word_data(client, reg, val);
+	}
 	return i2c_smbus_write_word_swapped(client, reg, val);
 }
 
@@ -848,6 +888,7 @@ static const struct i2c_device_id lm75_i2c_ids[] = {
 	{ .name = "max31725", .driver_data = max31725 },
 	{ .name = "max31726", .driver_data = max31725 },
 	{ .name = "mcp980x", .driver_data = mcp980x },
+	{ .name = "nct7715", .driver_data = nct7715 },
 	{ .name = "p3t1750", .driver_data = p3t1750 },
 	{ .name = "p3t1755", .driver_data = p3t1755 },
 	{ .name = "pct2075", .driver_data = pct2075 },
@@ -972,6 +1013,10 @@ static const struct of_device_id lm75_of_match[] = {
 		.compatible = "nxp,pct2075",
 		.data = (void *)pct2075
 	},
+	{
+		.compatible = "nuvoton,nct7715",
+		.data = (void *)nct7715
+	},
 	{
 		.compatible = "st,stds75",
 		.data = (void *)stds75
@@ -1129,13 +1174,21 @@ static int lm75_suspend(struct device *dev)
 {
 	struct lm75_data *data = dev_get_drvdata(dev);
 
-	return regmap_update_bits(data->regmap, LM75_REG_CONF, LM75_SHUTDOWN, LM75_SHUTDOWN);
+	if (data->kind == nct7715)
+		return regmap_update_bits(data->regmap, LM75_REG_CONF,
+					  NCT7715_CONFIG_SHUTDOWN,
+					  NCT7715_CONFIG_SHUTDOWN);
+	return regmap_update_bits(data->regmap, LM75_REG_CONF,
+				  LM75_SHUTDOWN, LM75_SHUTDOWN);
 }
 
 static int lm75_resume(struct device *dev)
 {
 	struct lm75_data *data = dev_get_drvdata(dev);
 
+	if (data->kind == nct7715)
+		return regmap_update_bits(data->regmap, LM75_REG_CONF,
+					  NCT7715_CONFIG_SHUTDOWN, 0);
 	return regmap_update_bits(data->regmap, LM75_REG_CONF, LM75_SHUTDOWN, 0);
 }
 
-- 
2.43.0