[PATCH v1] hwmon: (lm75) Add support for Nuvoton NCT7715
From: hsyemail2
Date: Mon Sep 07 2026 - 04:18:03 EST
From: Sheng-Yuan Huang <syhuang3@xxxxxxxxxxx>
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@xxxxxxxxxxx>
---
.../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@xxxxxx>
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