[PATCH v5 0/2] iio: adc: add Nuvoton NCT7201 ADC driver

[PATCH v5 0/2] iio: adc: add Nuvoton NCT7201 ADC driver

[Eason Yang]

Change since version 5:
 - Fix comments
 - Add NUVOTON NCT7201 IIO DRIVER section in MAINTAINERS
 - Add vdd-supply and vref-supply to the DT example
 - Remove mutex since the regmap should already have an internal lock
 - Remove redundant assigning values
 - Check errors on regmap_write

Change since version 4:
 - Fix comments
 - Add interrupts and reset-gpios to the DT example
 - Use the FIELD_PREP and FIELD_GET
 - Add use_single_write in regmap_config
 - Use regmap_access_table

Change since version 3:
 - Fix comments
 - Don't put nct720"x" in the name, just call it nct7201
 - Remove differential inputs until conversions are finished
 - Add NCT7201_ prefix in all macros and avoid the tables
 - Correct event threshold values in raw units
 - Add with and without interrupt callback function to have the event
   config part and one that doesn't
 - Remove print an error message if regmap_wirte failed case

Change since version 2:
 - Remvoe read-vin-data-size property, default use read word vin data
 - Use regmap instead of i2c smbus API
 - IIO should be IIO_CHAN_INFO_RAW and _SCALE not _PROCESSED
 - Use dev_xxx_probe in probe function and dev_xxx in other functions
 - Use devm_iio_device_register replace of iio_device_register
 - Use guard(mutex) replace of mutex_lock
 - Use get_unaligned_le16 conversion API

Changes since version 1:
 - Add new property in iio:adc binding document
 - Add new driver for Nuvoton NCT720x driver

Eason Yang (2):
  dt-bindings: iio: adc: add NCT7201 ADCs
  iio: adc: add support for Nuvoton NCT7201

 .../bindings/iio/adc/nuvoton,nct7201.yaml     |  71 +++
 MAINTAINERS                                   |   7 +
 drivers/iio/adc/Kconfig                       |  11 +
 drivers/iio/adc/Makefile                      |   1 +
 drivers/iio/adc/nct7201.c                     | 488 ++++++++++++++++++
 5 files changed, 578 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/adc/nuvoton,nct7201.yaml
 create mode 100644 drivers/iio/adc/nct7201.c

-- 
2.34.1

[PATCH v5 1/2] dt-bindings: iio: adc: add NCT7201 ADCs

[Eason Yang]

Add a binding specification for the Nuvoton NCT7201/NCT7202 up to 12-bit
ADCs with I2C interface.

Signed-off-by: Eason Yang <j2anfernee@gmail.com>
---
 .../bindings/iio/adc/nuvoton,nct7201.yaml     | 71 +++++++++++++++++++
 MAINTAINERS                                   |  6 ++
 2 files changed, 77 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/adc/nuvoton,nct7201.yaml

diff --git a/Documentation/devicetree/bindings/iio/adc/nuvoton,nct7201.yaml b/Documentation/devicetree/bindings/iio/adc/nuvoton,nct7201.yaml
new file mode 100644
index 000000000000..773e0cfd9f36
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/adc/nuvoton,nct7201.yaml
@@ -0,0 +1,71 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/adc/nuvoton,nct7201.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Nuvoton nct7201 and similar ADCs
+
+maintainers:
+  - Eason Yang <j2anfernee@gmail.com>
+
+description: |
+  The NCT7201/NCT7202 is a Nuvoton Hardware Monitor IC, contains up to 12
+  voltage monitoring channels, with SMBus interface, and up to 4 sets SMBus
+  address selection by ADDR connection. It also provides ALERT# signal for
+  event notification and reset input RSTIN# to recover it from a fault
+  condition.
+
+  NCT7201 contains 8 voltage monitor inputs (VIN1~VIN8).
+  NCT7202 contains 12 voltage monitor inputs (VIN1~VIN12).
+
+properties:
+  compatible:
+    enum:
+      - nuvoton,nct7201
+      - nuvoton,nct7202
+
+  reg:
+    maxItems: 1
+
+  vdd-supply:
+    description:
+      A 3.3V to supply that powers the chip.
+
+  vref-supply:
+    description:
+      The regulator supply for the ADC reference voltage.
+
+  interrupts:
+    maxItems: 1
+
+  reset-gpios:
+    maxItems: 1
+
+required:
+  - compatible
+  - reg
+
+additionalProperties: false
+
+examples:
+  - |
+
+    #include <dt-bindings/gpio/gpio.h>
+    #include <dt-bindings/interrupt-controller/irq.h>
+
+    i2c {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        adc@1d {
+            compatible = "nuvoton,nct7202";
+            reg = <0x1d>;
+            vdd-supply = <&vdd>;
+            vref-supply = <&vref>;
+            interrupt-parent = <&gpio3>;
+            interrupts = <30 IRQ_TYPE_LEVEL_LOW>;
+            reset-gpios = <&gpio3 28 GPIO_ACTIVE_LOW>;
+        };
+    };
+...
diff --git a/MAINTAINERS b/MAINTAINERS
index 96b827049501..f9ec68d4d8b4 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -17302,6 +17302,12 @@ F:	drivers/nubus/
 F:	include/linux/nubus.h
 F:	include/uapi/linux/nubus.h
 
+NUVOTON NCT7201 IIO DRIVER
+M:	Eason Yang <j2anfernee@gmail.com>
+L:	linux-iio@vger.kernel.org
+S:	Maintained
+F:	Documentation/devicetree/bindings/iio/adc/nuvoton,nct7201.yaml
+
 NVIDIA (rivafb and nvidiafb) FRAMEBUFFER DRIVER
 M:	Antonino Daplas <adaplas@gmail.com>
 L:	linux-fbdev@vger.kernel.org
-- 
2.34.1

Re: [PATCH v5 1/2] dt-bindings: iio: adc: add NCT7201 ADCs

[Krzysztof Kozlowski]

On 09/04/2025 03:23, Eason Yang wrote:
> +  interrupts:
> +    maxItems: 1
> +
> +  reset-gpios:
> +    maxItems: 1
> +
> +required:
> +  - compatible
> +  - reg
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +

If you are going to send a new version, drop blank line here.


Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>


Best regards,
Krzysztof

[PATCH v5 2/2] iio: adc: add support for Nuvoton NCT7201

[Eason Yang]

Add Nuvoton NCT7201/NCT7202 system voltage monitor 12-bit ADC driver

NCT7201/NCT7202 supports up to 12 analog voltage monitor inputs and up to
4 SMBus addresses by ADDR pin. Meanwhile, ALERT# hardware event pins for
independent alarm signals, and all the threshold values could be set for
system protection without any timing delay. It also supports reset input
RSTIN# to recover system from a fault condition.

Currently, only single-edge mode conversion and threshold events are
supported.

Signed-off-by: Eason Yang <j2anfernee@gmail.com>
---
 MAINTAINERS               |   1 +
 drivers/iio/adc/Kconfig   |  11 +
 drivers/iio/adc/Makefile  |   1 +
 drivers/iio/adc/nct7201.c | 488 ++++++++++++++++++++++++++++++++++++++
 4 files changed, 501 insertions(+)
 create mode 100644 drivers/iio/adc/nct7201.c

diff --git a/MAINTAINERS b/MAINTAINERS
index f9ec68d4d8b4..d155780e5ee0 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -17307,6 +17307,7 @@ M:	Eason Yang <j2anfernee@gmail.com>
 L:	linux-iio@vger.kernel.org
 S:	Maintained
 F:	Documentation/devicetree/bindings/iio/adc/nuvoton,nct7201.yaml
+F:	drivers/iio/adc/nct7201.c
 
 NVIDIA (rivafb and nvidiafb) FRAMEBUFFER DRIVER
 M:	Antonino Daplas <adaplas@gmail.com>
diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index 6529df1a498c..6d6af1b51b5e 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -1092,6 +1092,17 @@ config NAU7802
 	  To compile this driver as a module, choose M here: the
 	  module will be called nau7802.
 
+config NCT7201
+	tristate "Nuvoton Instruments NCT7201 and NCT7202 Power Monitor"
+	depends on I2C
+	select REGMAP_I2C
+	help
+	  If you say yes here you get support for the Nuvoton NCT7201 and
+	  NCT7202 Voltage Monitor.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called nct7201.
+
 config NPCM_ADC
 	tristate "Nuvoton NPCM ADC driver"
 	depends on ARCH_NPCM || COMPILE_TEST
diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
index 3e918c3eec69..54e8a7541af6 100644
--- a/drivers/iio/adc/Makefile
+++ b/drivers/iio/adc/Makefile
@@ -97,6 +97,7 @@ obj-$(CONFIG_MESON_SARADC) += meson_saradc.o
 obj-$(CONFIG_MP2629_ADC) += mp2629_adc.o
 obj-$(CONFIG_MXS_LRADC_ADC) += mxs-lradc-adc.o
 obj-$(CONFIG_NAU7802) += nau7802.o
+obj-$(CONFIG_NCT7201) += nct7201.o
 obj-$(CONFIG_NPCM_ADC) += npcm_adc.o
 obj-$(CONFIG_PAC1921) += pac1921.o
 obj-$(CONFIG_PAC1934) += pac1934.o
diff --git a/drivers/iio/adc/nct7201.c b/drivers/iio/adc/nct7201.c
new file mode 100644
index 000000000000..fe1ac8a28ab6
--- /dev/null
+++ b/drivers/iio/adc/nct7201.c
@@ -0,0 +1,488 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Driver for Nuvoton nct7201 and nct7202 power monitor chips.
+ *
+ * Copyright (c) 2024-2025 Nuvoton Technology corporation.
+ */
+
+#include <linux/array_size.h>
+#include <linux/bitfield.h>
+#include <linux/bits.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+#include <linux/types.h>
+#include <linux/unaligned.h>
+
+#include <linux/iio/events.h>
+#include <linux/iio/iio.h>
+
+#define NCT7201_VIN_MAX				12
+#define NCT7201_IN_SCALING				4995
+#define NCT7201_IN_SCALING_FACTOR			10000
+
+#define NCT7201_REG_INTERRUPT_STATUS_1			0x0C
+#define NCT7201_REG_INTERRUPT_STATUS_2			0x0D
+#define NCT7201_REG_VOLT_LOW_BYTE			0x0F
+#define NCT7201_REG_CONFIGURATION			0x10
+#define  NCT7201_BIT_CONFIGURATION_START		BIT(0)
+#define  NCT7201_BIT_CONFIGURATION_ALERT_MSK		BIT(1)
+#define  NCT7201_BIT_CONFIGURATION_CONV_RATE		BIT(2)
+#define  NCT7201_BIT_CONFIGURATION_RESET		BIT(7)
+
+#define NCT7201_REG_ADVANCED_CONFIGURATION		0x11
+#define  NCT7201_BIT_ADVANCED_CONF_MOD_ALERT		BIT(0)
+#define  NCT7201_BIT_ADVANCED_CONF_MOD_STS		BIT(1)
+#define  NCT7201_BIT_ADVANCED_CONF_FAULT_QUEUE		BIT(2)
+#define  NCT7201_BIT_ADVANCED_CONF_EN_DEEP_SHUTDOWN	BIT(4)
+#define  NCT7201_BIT_ADVANCED_CONF_EN_SMB_TIMEOUT	BIT(5)
+#define  NCT7201_BIT_ADVANCED_CONF_MOD_RSTIN		BIT(7)
+
+#define NCT7201_REG_CHANNEL_INPUT_MODE			0x12
+#define NCT7201_REG_CHANNEL_ENABLE_1			0x13
+#define  NCT7201_REG_CHANNEL_ENABLE_1_MASK		GENMASK(7, 0)
+#define NCT7201_REG_CHANNEL_ENABLE_2			0x14
+#define  NCT7201_REG_CHANNEL_ENABLE_2_MASK		GENMASK(3, 0)
+#define NCT7201_REG_INTERRUPT_MASK_1			0x15
+#define NCT7201_REG_INTERRUPT_MASK_2			0x16
+#define NCT7201_REG_BUSY_STATUS			0x1E
+#define  NCT7201_BIT_BUSY				BIT(0)
+#define  NCT7201_BIT_PWR_UP				BIT(1)
+#define NCT7201_REG_ONE_SHOT				0x1F
+#define NCT7201_REG_SMUS_ADDRESS			0xFC
+#define NCT7201_REG_VIN_MASK				GENMASK(15, 3)
+
+#define NCT7201_REG_VIN(i)				(i)
+#define NCT7201_REG_VIN_HIGH_LIMIT(i)			(0x20 + (i) * 2)
+#define NCT7201_REG_VIN_LOW_LIMIT(i)			(0x21 + (i) * 2)
+
+static const struct regmap_range nct7201_read_reg_range[] = {
+	regmap_reg_range(NCT7201_REG_INTERRUPT_STATUS_1, NCT7201_REG_BUSY_STATUS),
+	regmap_reg_range(NCT7201_REG_SMUS_ADDRESS, NCT7201_REG_SMUS_ADDRESS),
+};
+
+static const struct regmap_access_table nct7201_readable_regs_tbl = {
+	.yes_ranges = nct7201_read_reg_range,
+	.n_yes_ranges = ARRAY_SIZE(nct7201_read_reg_range),
+};
+
+static const struct regmap_range nct7201_write_reg_range[] = {
+	regmap_reg_range(NCT7201_REG_CONFIGURATION, NCT7201_REG_INTERRUPT_MASK_2),
+	regmap_reg_range(NCT7201_REG_ONE_SHOT, NCT7201_REG_ONE_SHOT),
+};
+
+static const struct regmap_access_table nct7201_writeable_regs_tbl = {
+	.yes_ranges = nct7201_write_reg_range,
+	.n_yes_ranges = ARRAY_SIZE(nct7201_write_reg_range),
+};
+
+static const struct regmap_range nct7201_read_vin_reg_range[] = {
+	regmap_reg_range(NCT7201_REG_VIN(0), NCT7201_REG_VIN(NCT7201_VIN_MAX - 1)),
+	regmap_reg_range(NCT7201_REG_VIN_HIGH_LIMIT(0),
+			 NCT7201_REG_VIN_LOW_LIMIT(NCT7201_VIN_MAX - 1)),
+};
+
+static const struct regmap_access_table nct7201_readable_vin_regs_tbl = {
+	.yes_ranges = nct7201_read_vin_reg_range,
+	.n_yes_ranges = ARRAY_SIZE(nct7201_read_vin_reg_range),
+};
+
+static const struct regmap_range nct7201_write_vin_reg_range[] = {
+	regmap_reg_range(NCT7201_REG_VIN_HIGH_LIMIT(0),
+			 NCT7201_REG_VIN_LOW_LIMIT(NCT7201_VIN_MAX - 1)),
+};
+
+static const struct regmap_access_table nct7201_writeable_vin_regs_tbl = {
+	.yes_ranges = nct7201_write_vin_reg_range,
+	.n_yes_ranges = ARRAY_SIZE(nct7201_write_vin_reg_range),
+};
+
+static const struct regmap_config nct7201_regmap8_config = {
+	.name = "vin-data-read-byte",
+	.reg_bits = 8,
+	.val_bits = 8,
+	.use_single_write = true,
+	.max_register = 0xff,
+	.rd_table = &nct7201_readable_regs_tbl,
+	.wr_table = &nct7201_writeable_regs_tbl,
+};
+
+static const struct regmap_config nct7201_regmap16_config = {
+	.name = "vin-data-read-word",
+	.reg_bits = 8,
+	.val_bits = 16,
+	.max_register = 0xff,
+	.rd_table = &nct7201_readable_vin_regs_tbl,
+	.wr_table = &nct7201_writeable_vin_regs_tbl,
+};
+
+struct nct7201_chip_info {
+	struct i2c_client *client;
+	struct regmap *regmap;
+	struct regmap *regmap16;
+	int num_vin_channels;
+	u16 vin_mask;
+};
+
+struct nct7201_adc_model_data {
+	const char *model_name;
+	const struct iio_chan_spec *channels;
+	const int num_channels;
+	int num_vin_channels;
+};
+
+static const struct iio_event_spec nct7201_events[] = {
+	{
+		.type = IIO_EV_TYPE_THRESH,
+		.dir = IIO_EV_DIR_RISING,
+		.mask_separate = BIT(IIO_EV_INFO_VALUE) |
+				 BIT(IIO_EV_INFO_ENABLE),
+	}, {
+		.type = IIO_EV_TYPE_THRESH,
+		.dir = IIO_EV_DIR_FALLING,
+		.mask_separate = BIT(IIO_EV_INFO_VALUE) |
+				 BIT(IIO_EV_INFO_ENABLE),
+	},
+};
+
+#define NCT7201_VOLTAGE_CHANNEL(num)					\
+	{								\
+		.type = IIO_VOLTAGE,					\
+		.indexed = 1,						\
+		.channel = (num + 1),					\
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
+		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
+		.address = num,						\
+		.event_spec = nct7201_events,				\
+		.num_event_specs = ARRAY_SIZE(nct7201_events),		\
+	}
+
+static const struct iio_chan_spec nct7201_channels[] = {
+	NCT7201_VOLTAGE_CHANNEL(0),
+	NCT7201_VOLTAGE_CHANNEL(1),
+	NCT7201_VOLTAGE_CHANNEL(2),
+	NCT7201_VOLTAGE_CHANNEL(3),
+	NCT7201_VOLTAGE_CHANNEL(4),
+	NCT7201_VOLTAGE_CHANNEL(5),
+	NCT7201_VOLTAGE_CHANNEL(6),
+	NCT7201_VOLTAGE_CHANNEL(7),
+};
+
+static const struct iio_chan_spec nct7202_channels[] = {
+	NCT7201_VOLTAGE_CHANNEL(0),
+	NCT7201_VOLTAGE_CHANNEL(1),
+	NCT7201_VOLTAGE_CHANNEL(2),
+	NCT7201_VOLTAGE_CHANNEL(3),
+	NCT7201_VOLTAGE_CHANNEL(4),
+	NCT7201_VOLTAGE_CHANNEL(5),
+	NCT7201_VOLTAGE_CHANNEL(6),
+	NCT7201_VOLTAGE_CHANNEL(7),
+	NCT7201_VOLTAGE_CHANNEL(8),
+	NCT7201_VOLTAGE_CHANNEL(9),
+	NCT7201_VOLTAGE_CHANNEL(10),
+	NCT7201_VOLTAGE_CHANNEL(11),
+};
+
+static int nct7201_read_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *chan,
+			    int *val, int *val2, long mask)
+{
+	struct nct7201_chip_info *chip = iio_priv(indio_dev);
+	unsigned int value;
+	int err;
+
+	if (chan->type != IIO_VOLTAGE)
+		return -EOPNOTSUPP;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		err = regmap_read(chip->regmap16, NCT7201_REG_VIN(chan->address), &value);
+		if (err < 0)
+			return err;
+		*val = FIELD_GET(NCT7201_REG_VIN_MASK, value);
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_SCALE:
+		/* From the datasheet, we have to multiply by 0.0004995 */
+		*val = 0;
+		*val2 = 499500;
+		return IIO_VAL_INT_PLUS_NANO;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int nct7201_read_event_value(struct iio_dev *indio_dev,
+				    const struct iio_chan_spec *chan,
+				    enum iio_event_type type,
+				    enum iio_event_direction dir,
+				    enum iio_event_info info,
+				    int *val, int *val2)
+{
+	struct nct7201_chip_info *chip = iio_priv(indio_dev);
+	unsigned int value;
+	int err;
+
+	if (chan->type != IIO_VOLTAGE)
+		return -EOPNOTSUPP;
+
+	if (info != IIO_EV_INFO_VALUE)
+		return -EINVAL;
+
+	if (dir == IIO_EV_DIR_FALLING) {
+		err = regmap_read(chip->regmap16, NCT7201_REG_VIN_LOW_LIMIT(chan->address),
+				  &value);
+		if (err < 0)
+			return err;
+	} else {
+		err = regmap_read(chip->regmap16, NCT7201_REG_VIN_HIGH_LIMIT(chan->address),
+				  &value);
+		if (err < 0)
+			return err;
+	}
+
+	*val = FIELD_GET(NCT7201_REG_VIN_MASK, value);
+
+	return IIO_VAL_INT;
+}
+
+static int nct7201_write_event_value(struct iio_dev *indio_dev,
+				     const struct iio_chan_spec *chan,
+				     enum iio_event_type type,
+				     enum iio_event_direction dir,
+				     enum iio_event_info info,
+				     int val, int val2)
+{
+	struct nct7201_chip_info *chip = iio_priv(indio_dev);
+	int  err = 0;
+
+	if (chan->type != IIO_VOLTAGE)
+		return -EOPNOTSUPP;
+
+	if (info != IIO_EV_INFO_VALUE)
+		return -EOPNOTSUPP;
+
+	if (dir == IIO_EV_DIR_FALLING) {
+		err = regmap_write(chip->regmap16, NCT7201_REG_VIN_LOW_LIMIT(chan->address),
+				   FIELD_PREP(NCT7201_REG_VIN_MASK, val));
+		if (err < 0)
+			return err;
+	} else {
+		err = regmap_write(chip->regmap16, NCT7201_REG_VIN_HIGH_LIMIT(chan->address),
+				   FIELD_PREP(NCT7201_REG_VIN_MASK, val));
+		if (err < 0)
+			return err;
+	}
+
+	return 0;
+}
+
+static int nct7201_read_event_config(struct iio_dev *indio_dev,
+				     const struct iio_chan_spec *chan,
+				     enum iio_event_type type,
+				     enum iio_event_direction dir)
+{
+	struct nct7201_chip_info *chip = iio_priv(indio_dev);
+
+	if (chan->type != IIO_VOLTAGE)
+		return -EOPNOTSUPP;
+
+	return !!(chip->vin_mask & BIT(chan->address));
+}
+
+static int nct7201_write_event_config(struct iio_dev *indio_dev,
+				      const struct iio_chan_spec *chan,
+				      enum iio_event_type type,
+				      enum iio_event_direction dir,
+				      bool state)
+{
+	struct nct7201_chip_info *chip = iio_priv(indio_dev);
+	unsigned int mask;
+	int err;
+
+	if (chan->type != IIO_VOLTAGE)
+		return -EOPNOTSUPP;
+
+	mask = BIT(chan->address);
+
+	if (state)
+		chip->vin_mask |= mask;
+	else
+		chip->vin_mask &= ~mask;
+
+	if (chip->num_vin_channels <= 8) {
+		err = regmap_write(chip->regmap, NCT7201_REG_CHANNEL_ENABLE_1,
+				   chip->vin_mask);
+		if (err < 0)
+			return err;
+	} else {
+		err = regmap_bulk_write(chip->regmap, NCT7201_REG_CHANNEL_ENABLE_1,
+					&chip->vin_mask, sizeof(chip->vin_mask));
+		if (err < 0)
+			return err;
+	}
+
+	return 0;
+}
+
+static const struct iio_info nct7201_info = {
+	.read_raw = nct7201_read_raw,
+	.read_event_config = nct7201_read_event_config,
+	.write_event_config = nct7201_write_event_config,
+	.read_event_value = nct7201_read_event_value,
+	.write_event_value = nct7201_write_event_value,
+};
+
+static const struct iio_info nct7201_info_no_irq = {
+	.read_raw = nct7201_read_raw,
+};
+
+static const struct nct7201_adc_model_data nct7201_model_data = {
+	.model_name = "nct7201",
+	.channels = nct7201_channels,
+	.num_channels = ARRAY_SIZE(nct7201_channels),
+	.num_vin_channels = 8,
+};
+
+static const struct nct7201_adc_model_data nct7202_model_data = {
+	.model_name = "nct7202",
+	.channels = nct7202_channels,
+	.num_channels = ARRAY_SIZE(nct7202_channels),
+	.num_vin_channels = 12,
+};
+
+static int nct7201_init_chip(struct nct7201_chip_info *chip)
+{
+	u8 data[2] = {0};
+	unsigned int value;
+	int err;
+
+	err = regmap_write(chip->regmap, NCT7201_REG_CONFIGURATION,
+			   NCT7201_BIT_CONFIGURATION_RESET);
+	if (err < 0)
+		return dev_err_probe(&chip->client->dev, -EIO,
+				     "Failed to write NCT7201_REG_CONFIGURATION\n");
+
+	/*
+	 * After about 25 msecs, the device should be ready and then the Power
+	 * Up bit will be set to 1. If not, wait for it.
+	 */
+	mdelay(25);
+	err = regmap_read(chip->regmap, NCT7201_REG_BUSY_STATUS, &value);
+	if (err < 0)
+		return err;
+	if (!(value & NCT7201_BIT_PWR_UP))
+		return dev_err_probe(&chip->client->dev, -EIO,
+				     "Failed to power up after reset\n");
+
+	/* Enable Channel */
+	if (chip->num_vin_channels <= 8) {
+		data[0] = NCT7201_REG_CHANNEL_ENABLE_1_MASK;
+		err = regmap_write(chip->regmap, NCT7201_REG_CHANNEL_ENABLE_1, data[0]);
+		if (err < 0)
+			return dev_err_probe(&chip->client->dev, -EIO,
+					     "Failed to write NCT7201_REG_CHANNEL_ENABLE_1\n");
+	} else {
+		data[0] = NCT7201_REG_CHANNEL_ENABLE_1_MASK;
+		data[1] = NCT7201_REG_CHANNEL_ENABLE_2_MASK;
+		err = regmap_bulk_write(chip->regmap, NCT7201_REG_CHANNEL_ENABLE_1,
+					data, ARRAY_SIZE(data));
+		if (err < 0)
+			return dev_err_probe(&chip->client->dev, -EIO,
+					     "Failed to write NCT7201_REG_CHANNEL_ENABLE_1 and NCT7201_REG_CHANNEL_ENABLE_2\n");
+	}
+	chip->vin_mask = get_unaligned_le16(data);
+
+	/* Start monitoring if needed */
+	err = regmap_read(chip->regmap, NCT7201_REG_CONFIGURATION, &value);
+	if (err < 0)
+		return dev_err_probe(&chip->client->dev, -EIO,
+				     "Failed to read NCT7201_REG_CONFIGURATION\n");
+
+	regmap_set_bits(chip->regmap, NCT7201_REG_CONFIGURATION, NCT7201_BIT_CONFIGURATION_START);
+
+	return 0;
+}
+
+static int nct7201_probe(struct i2c_client *client)
+{
+	const struct nct7201_adc_model_data *model_data;
+	struct nct7201_chip_info *chip;
+	struct iio_dev *indio_dev;
+	int ret;
+
+	model_data = i2c_get_match_data(client);
+	if (!model_data)
+		return -EINVAL;
+
+	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*chip));
+	if (!indio_dev)
+		return -ENOMEM;
+	chip = iio_priv(indio_dev);
+
+	chip->regmap = devm_regmap_init_i2c(client, &nct7201_regmap8_config);
+	if (IS_ERR(chip->regmap))
+		return dev_err_probe(&client->dev, PTR_ERR(chip->regmap),
+				     "Failed to init regmap\n");
+
+	chip->regmap16 = devm_regmap_init_i2c(client, &nct7201_regmap16_config);
+	if (IS_ERR(chip->regmap16))
+		return dev_err_probe(&client->dev, PTR_ERR(chip->regmap16),
+				     "Failed to init regmap16\n");
+
+	chip->num_vin_channels = model_data->num_vin_channels;
+
+	chip->client = client;
+
+	ret = nct7201_init_chip(chip);
+	if (ret < 0)
+		return ret;
+
+	indio_dev->name = model_data->model_name;
+	indio_dev->channels = model_data->channels;
+	indio_dev->num_channels = model_data->num_channels;
+	if (client->irq)
+		indio_dev->info = &nct7201_info;
+	else
+		indio_dev->info = &nct7201_info_no_irq;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+
+	return devm_iio_device_register(&client->dev, indio_dev);
+}
+
+static const struct i2c_device_id nct7201_id[] = {
+	{ .name = "nct7201", .driver_data = (kernel_ulong_t)&nct7201_model_data },
+	{ .name = "nct7202", .driver_data = (kernel_ulong_t)&nct7202_model_data },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, nct7201_id);
+
+static const struct of_device_id nct7201_of_match[] = {
+	{
+		.compatible = "nuvoton,nct7201",
+		.data = &nct7201_model_data,
+	},
+	{
+		.compatible = "nuvoton,nct7202",
+		.data = &nct7202_model_data,
+	},
+	{ }
+};
+MODULE_DEVICE_TABLE(of, nct7201_of_match);
+
+static struct i2c_driver nct7201_driver = {
+	.driver = {
+		.name	= "nct7201",
+		.of_match_table = nct7201_of_match,
+	},
+	.probe = nct7201_probe,
+	.id_table = nct7201_id,
+};
+module_i2c_driver(nct7201_driver);
+
+MODULE_AUTHOR("Eason Yang <j2anfernee@gmail.com>");
+MODULE_DESCRIPTION("Nuvoton NCT7201 voltage monitor driver");
+MODULE_LICENSE("GPL");
-- 
2.34.1

Re: [PATCH v5 2/2] iio: adc: add support for Nuvoton NCT7201

[Andy Shevchenko]

On Wed, Apr 09, 2025 at 09:23:51AM +0800, Eason Yang wrote:
> Add Nuvoton NCT7201/NCT7202 system voltage monitor 12-bit ADC driver
> 
> NCT7201/NCT7202 supports up to 12 analog voltage monitor inputs and up to
> 4 SMBus addresses by ADDR pin. Meanwhile, ALERT# hardware event pins for
> independent alarm signals, and all the threshold values could be set for
> system protection without any timing delay. It also supports reset input
> RSTIN# to recover system from a fault condition.
> 
> Currently, only single-edge mode conversion and threshold events are
> supported.

> +#include <linux/array_size.h>
> +#include <linux/bitfield.h>
> +#include <linux/bits.h>
> +#include <linux/delay.h>
> +#include <linux/device.h>
> +#include <linux/err.h>
> +#include <linux/i2c.h>
> +#include <linux/mod_devicetable.h>
> +#include <linux/module.h>
> +#include <linux/regmap.h>
> +#include <linux/types.h>
> +#include <linux/unaligned.h>

...

> +#define NCT7201_VIN_MAX				12

Is this in volts? Can you add a unit suffix?

...

> +#define NCT7201_IN_SCALING				4995

Interesting number, just want to confirm it's indeed 4995 and not 4095.

...

> +static int nct7201_read_event_value(struct iio_dev *indio_dev,
> +				    const struct iio_chan_spec *chan,
> +				    enum iio_event_type type,
> +				    enum iio_event_direction dir,
> +				    enum iio_event_info info,
> +				    int *val, int *val2)
> +{
> +	struct nct7201_chip_info *chip = iio_priv(indio_dev);
> +	unsigned int value;
> +	int err;
> +
> +	if (chan->type != IIO_VOLTAGE)
> +		return -EOPNOTSUPP;
> +
> +	if (info != IIO_EV_INFO_VALUE)
> +		return -EINVAL;

> +	if (dir == IIO_EV_DIR_FALLING) {
> +		err = regmap_read(chip->regmap16, NCT7201_REG_VIN_LOW_LIMIT(chan->address),
> +				  &value);
> +		if (err < 0)
> +			return err;
> +	} else {
> +		err = regmap_read(chip->regmap16, NCT7201_REG_VIN_HIGH_LIMIT(chan->address),
> +				  &value);
> +		if (err < 0)
> +			return err;
> +	}

	if (dir == IIO_EV_DIR_FALLING) {
		err = regmap_read(chip->regmap16, NCT7201_REG_VIN_LOW_LIMIT(chan->address),
				  &value);
	} else {
		err = regmap_read(chip->regmap16, NCT7201_REG_VIN_HIGH_LIMIT(chan->address),
				  &value);
	}
	if (err)
		return err;

Here and elsewhere why ' < 0' is used? Do you expect positive return values
from those?

> +	*val = FIELD_GET(NCT7201_REG_VIN_MASK, value);
> +
> +	return IIO_VAL_INT;
> +}

...

> +static int nct7201_write_event_value(struct iio_dev *indio_dev,
> +				     const struct iio_chan_spec *chan,
> +				     enum iio_event_type type,
> +				     enum iio_event_direction dir,
> +				     enum iio_event_info info,
> +				     int val, int val2)
> +{
> +	struct nct7201_chip_info *chip = iio_priv(indio_dev);

> +	int  err = 0;

Useless assignment.

> +	if (chan->type != IIO_VOLTAGE)
> +		return -EOPNOTSUPP;
> +
> +	if (info != IIO_EV_INFO_VALUE)
> +		return -EOPNOTSUPP;
> +
> +	if (dir == IIO_EV_DIR_FALLING) {
> +		err = regmap_write(chip->regmap16, NCT7201_REG_VIN_LOW_LIMIT(chan->address),
> +				   FIELD_PREP(NCT7201_REG_VIN_MASK, val));
> +		if (err < 0)
> +			return err;
> +	} else {
> +		err = regmap_write(chip->regmap16, NCT7201_REG_VIN_HIGH_LIMIT(chan->address),
> +				   FIELD_PREP(NCT7201_REG_VIN_MASK, val));
> +		if (err < 0)
> +			return err;
> +	}
> +
> +	return 0;

	if (dir == IIO_EV_DIR_FALLING) {
		err = regmap_write(chip->regmap16, NCT7201_REG_VIN_LOW_LIMIT(chan->address),
				   FIELD_PREP(NCT7201_REG_VIN_MASK, val));
	} else {
		err = regmap_write(chip->regmap16, NCT7201_REG_VIN_HIGH_LIMIT(chan->address),
				   FIELD_PREP(NCT7201_REG_VIN_MASK, val));
	}
	return err;


> +}

...

> +static int nct7201_write_event_config(struct iio_dev *indio_dev,
> +				      const struct iio_chan_spec *chan,
> +				      enum iio_event_type type,
> +				      enum iio_event_direction dir,
> +				      bool state)
> +{
> +	struct nct7201_chip_info *chip = iio_priv(indio_dev);
> +	unsigned int mask;
> +	int err;
> +
> +	if (chan->type != IIO_VOLTAGE)
> +		return -EOPNOTSUPP;
> +
> +	mask = BIT(chan->address);
> +
> +	if (state)
> +		chip->vin_mask |= mask;
> +	else
> +		chip->vin_mask &= ~mask;

> +	if (chip->num_vin_channels <= 8) {
> +		err = regmap_write(chip->regmap, NCT7201_REG_CHANNEL_ENABLE_1,
> +				   chip->vin_mask);
> +		if (err < 0)
> +			return err;
> +	} else {
> +		err = regmap_bulk_write(chip->regmap, NCT7201_REG_CHANNEL_ENABLE_1,
> +					&chip->vin_mask, sizeof(chip->vin_mask));
> +		if (err < 0)
> +			return err;
> +	}
> +
> +	return 0;

Same as above.

> +}

...

> +static int nct7201_init_chip(struct nct7201_chip_info *chip)
> +{
> +	u8 data[2] = {0};

'0' is not needed. Shouldn't this be __le16 or __be16 instead?

> +	unsigned int value;
> +	int err;
> +
> +	err = regmap_write(chip->regmap, NCT7201_REG_CONFIGURATION,
> +			   NCT7201_BIT_CONFIGURATION_RESET);
> +	if (err < 0)
> +		return dev_err_probe(&chip->client->dev, -EIO,

	struct device *dev = &chip->client->dev;

at the top of the function will help a lot in tiding up the below code.

Shadowed error code, why?

> +				     "Failed to write NCT7201_REG_CONFIGURATION\n");
> +
> +	/*
> +	 * After about 25 msecs, the device should be ready and then the Power
> +	 * Up bit will be set to 1. If not, wait for it.
> +	 */
> +	mdelay(25);

No sleep? Why? Can't you use fsleep()?

> +	err = regmap_read(chip->regmap, NCT7201_REG_BUSY_STATUS, &value);
> +	if (err < 0)
> +		return err;
> +	if (!(value & NCT7201_BIT_PWR_UP))
> +		return dev_err_probe(&chip->client->dev, -EIO,

Shadowed error code, why?

> +				     "Failed to power up after reset\n");
> +
> +	/* Enable Channel */
> +	if (chip->num_vin_channels <= 8) {
> +		data[0] = NCT7201_REG_CHANNEL_ENABLE_1_MASK;
> +		err = regmap_write(chip->regmap, NCT7201_REG_CHANNEL_ENABLE_1, data[0]);
> +		if (err < 0)
> +			return dev_err_probe(&chip->client->dev, -EIO,

Why error code is shadowed?

> +					     "Failed to write NCT7201_REG_CHANNEL_ENABLE_1\n");
> +	} else {
> +		data[0] = NCT7201_REG_CHANNEL_ENABLE_1_MASK;
> +		data[1] = NCT7201_REG_CHANNEL_ENABLE_2_MASK;
> +		err = regmap_bulk_write(chip->regmap, NCT7201_REG_CHANNEL_ENABLE_1,
> +					data, ARRAY_SIZE(data));
> +		if (err < 0)
> +			return dev_err_probe(&chip->client->dev, -EIO,

Ditto.

> +					     "Failed to write NCT7201_REG_CHANNEL_ENABLE_1 and NCT7201_REG_CHANNEL_ENABLE_2\n");
> +	}

Just make it 16-bit type, define one value and use just simple English
in the error message: "Failed to write channel enable mask\n");

Same to all your error messages.

> +	chip->vin_mask = get_unaligned_le16(data);
> +
> +	/* Start monitoring if needed */
> +	err = regmap_read(chip->regmap, NCT7201_REG_CONFIGURATION, &value);
> +	if (err < 0)
> +		return dev_err_probe(&chip->client->dev, -EIO,
> +				     "Failed to read NCT7201_REG_CONFIGURATION\n");

> +	regmap_set_bits(chip->regmap, NCT7201_REG_CONFIGURATION, NCT7201_BIT_CONFIGURATION_START);

> +	return 0;

No error check? Why?

> +}

...

> +static int nct7201_probe(struct i2c_client *client)
> +{
> +	const struct nct7201_adc_model_data *model_data;

	struct device *dev = &client->dev;

> +	struct nct7201_chip_info *chip;
> +	struct iio_dev *indio_dev;
> +	int ret;
> +
> +	model_data = i2c_get_match_data(client);
> +	if (!model_data)
> +		return -EINVAL;

ENODEV is more suitable here.

> +
> +	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*chip));
> +	if (!indio_dev)
> +		return -ENOMEM;
> +	chip = iio_priv(indio_dev);
> +
> +	chip->regmap = devm_regmap_init_i2c(client, &nct7201_regmap8_config);
> +	if (IS_ERR(chip->regmap))
> +		return dev_err_probe(&client->dev, PTR_ERR(chip->regmap),
> +				     "Failed to init regmap\n");
> +
> +	chip->regmap16 = devm_regmap_init_i2c(client, &nct7201_regmap16_config);
> +	if (IS_ERR(chip->regmap16))
> +		return dev_err_probe(&client->dev, PTR_ERR(chip->regmap16),
> +				     "Failed to init regmap16\n");
> +
> +	chip->num_vin_channels = model_data->num_vin_channels;

> +	chip->client = client;

How exactly is _client_ used elsewhere? Shouldn't it be just a struct device
pointer?

> +	ret = nct7201_init_chip(chip);
> +	if (ret < 0)

Do you expect positive returned values? What is their meaning?
Why do you skip them?

> +		return ret;
> +
> +	indio_dev->name = model_data->model_name;
> +	indio_dev->channels = model_data->channels;
> +	indio_dev->num_channels = model_data->num_channels;
> +	if (client->irq)
> +		indio_dev->info = &nct7201_info;
> +	else
> +		indio_dev->info = &nct7201_info_no_irq;
> +	indio_dev->modes = INDIO_DIRECT_MODE;
> +
> +	return devm_iio_device_register(&client->dev, indio_dev);
> +}

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v5 2/2] iio: adc: add support for Nuvoton NCT7201

[Yu-Hsian Yang]

Dear Andy,

Thanks for the review and the comments.
Will fix all.

Andy Shevchenko <andriy.shevchenko@linux.intel.com> 於 2025年4月10日 週四 上午12:19寫道：
>
> On Wed, Apr 09, 2025 at 09:23:51AM +0800, Eason Yang wrote:
> > Add Nuvoton NCT7201/NCT7202 system voltage monitor 12-bit ADC driver
> >
> > NCT7201/NCT7202 supports up to 12 analog voltage monitor inputs and up to
> > 4 SMBus addresses by ADDR pin. Meanwhile, ALERT# hardware event pins for
> > independent alarm signals, and all the threshold values could be set for
> > system protection without any timing delay. It also supports reset input
> > RSTIN# to recover system from a fault condition.
> >
> > Currently, only single-edge mode conversion and threshold events are
> > supported.
>
> > +#include <linux/array_size.h>
> > +#include <linux/bitfield.h>
> > +#include <linux/bits.h>
> > +#include <linux/delay.h>
> > +#include <linux/device.h>
> > +#include <linux/err.h>
> > +#include <linux/i2c.h>
> > +#include <linux/mod_devicetable.h>
> > +#include <linux/module.h>
> > +#include <linux/regmap.h>
> > +#include <linux/types.h>
> > +#include <linux/unaligned.h>
>
> ...
>
> > +#define NCT7201_VIN_MAX                              12
>
> Is this in volts? Can you add a unit suffix?

Rename it as
#define NCT7201_MAX_CHANNEL 12

>
> ...
>
> > +#define NCT7201_IN_SCALING                           4995
> > +#define NCT720X_IN_SCALING_FACTOR         10000
> Interesting number, just want to confirm it's indeed 4995 and not 4095.
>

These definitions are for real voltage calculations,
the formula is Voltage(V) = 13bitCountValue * 0.0004995
However, the definitions are not used anymore.
So remove them.

> ...
>
> > +static int nct7201_read_event_value(struct iio_dev *indio_dev,
> > +                                 const struct iio_chan_spec *chan,
> > +                                 enum iio_event_type type,
> > +                                 enum iio_event_direction dir,
> > +                                 enum iio_event_info info,
> > +                                 int *val, int *val2)
> > +{
> > +     struct nct7201_chip_info *chip = iio_priv(indio_dev);
> > +     unsigned int value;
> > +     int err;
> > +
> > +     if (chan->type != IIO_VOLTAGE)
> > +             return -EOPNOTSUPP;
> > +
> > +     if (info != IIO_EV_INFO_VALUE)
> > +             return -EINVAL;
>
> > +     if (dir == IIO_EV_DIR_FALLING) {
> > +             err = regmap_read(chip->regmap16, NCT7201_REG_VIN_LOW_LIMIT(chan->address),
> > +                               &value);
> > +             if (err < 0)
> > +                     return err;
> > +     } else {
> > +             err = regmap_read(chip->regmap16, NCT7201_REG_VIN_HIGH_LIMIT(chan->address),
> > +                               &value);
> > +             if (err < 0)
> > +                     return err;
> > +     }
>
>         if (dir == IIO_EV_DIR_FALLING) {
>                 err = regmap_read(chip->regmap16, NCT7201_REG_VIN_LOW_LIMIT(chan->address),
>                                   &value);
>         } else {
>                 err = regmap_read(chip->regmap16, NCT7201_REG_VIN_HIGH_LIMIT(chan->address),
>                                   &value);
>         }
>         if (err)
>                 return err;
>
> Here and elsewhere why ' < 0' is used? Do you expect positive return values
> from those?
>

In regmap_read function, A value of zero will be returned on success,
a negative errno will be returned in error cases.
We don't have a positive return case.


> > +     *val = FIELD_GET(NCT7201_REG_VIN_MASK, value);
> > +
> > +     return IIO_VAL_INT;
> > +}
>
> ...
>
> > +static int nct7201_write_event_value(struct iio_dev *indio_dev,
> > +                                  const struct iio_chan_spec *chan,
> > +                                  enum iio_event_type type,
> > +                                  enum iio_event_direction dir,
> > +                                  enum iio_event_info info,
> > +                                  int val, int val2)
> > +{
> > +     struct nct7201_chip_info *chip = iio_priv(indio_dev);
>
> > +     int  err = 0;
>
> Useless assignment.
>

> > +     if (chan->type != IIO_VOLTAGE)
> > +             return -EOPNOTSUPP;
> > +
> > +     if (info != IIO_EV_INFO_VALUE)
> > +             return -EOPNOTSUPP;
> > +
> > +     if (dir == IIO_EV_DIR_FALLING) {
> > +             err = regmap_write(chip->regmap16, NCT7201_REG_VIN_LOW_LIMIT(chan->address),
> > +                                FIELD_PREP(NCT7201_REG_VIN_MASK, val));
> > +             if (err < 0)
> > +                     return err;
> > +     } else {
> > +             err = regmap_write(chip->regmap16, NCT7201_REG_VIN_HIGH_LIMIT(chan->address),
> > +                                FIELD_PREP(NCT7201_REG_VIN_MASK, val));
> > +             if (err < 0)
> > +                     return err;
> > +     }
> > +
> > +     return 0;
>
>         if (dir == IIO_EV_DIR_FALLING) {
>                 err = regmap_write(chip->regmap16, NCT7201_REG_VIN_LOW_LIMIT(chan->address),
>                                    FIELD_PREP(NCT7201_REG_VIN_MASK, val));
>         } else {
>                 err = regmap_write(chip->regmap16, NCT7201_REG_VIN_HIGH_LIMIT(chan->address),
>                                    FIELD_PREP(NCT7201_REG_VIN_MASK, val));
>         }
>         return err;
>
>
> > +}
>
> ...
>
> > +static int nct7201_write_event_config(struct iio_dev *indio_dev,
> > +                                   const struct iio_chan_spec *chan,
> > +                                   enum iio_event_type type,
> > +                                   enum iio_event_direction dir,
> > +                                   bool state)
> > +{
> > +     struct nct7201_chip_info *chip = iio_priv(indio_dev);
> > +     unsigned int mask;
> > +     int err;
> > +
> > +     if (chan->type != IIO_VOLTAGE)
> > +             return -EOPNOTSUPP;
> > +
> > +     mask = BIT(chan->address);
> > +
> > +     if (state)
> > +             chip->vin_mask |= mask;
> > +     else
> > +             chip->vin_mask &= ~mask;
>
> > +     if (chip->num_vin_channels <= 8) {
> > +             err = regmap_write(chip->regmap, NCT7201_REG_CHANNEL_ENABLE_1,
> > +                                chip->vin_mask);
> > +             if (err < 0)
> > +                     return err;
> > +     } else {
> > +             err = regmap_bulk_write(chip->regmap, NCT7201_REG_CHANNEL_ENABLE_1,
> > +                                     &chip->vin_mask, sizeof(chip->vin_mask));
> > +             if (err < 0)
> > +                     return err;
> > +     }
> > +
> > +     return 0;
>
> Same as above.
>
> > +}
>
> ...
>
> > +static int nct7201_init_chip(struct nct7201_chip_info *chip)
> > +{
> > +     u8 data[2] = {0};
>
> '0' is not needed. Shouldn't this be __le16 or __be16 instead?
>

+ __be16 data = NCT7201_REG_CHANNEL_ENABLE_MASK;

> > +     unsigned int value;
> > +     int err;
> > +
> > +     err = regmap_write(chip->regmap, NCT7201_REG_CONFIGURATION,
> > +                        NCT7201_BIT_CONFIGURATION_RESET);
> > +     if (err < 0)
> > +             return dev_err_probe(&chip->client->dev, -EIO,
>
>         struct device *dev = &chip->client->dev;
>
> at the top of the function will help a lot in tiding up the below code.
>
> Shadowed error code, why?
>

Do not shadow the return code by -EIO and let the regmap API caller decide.

> > +                                  "Failed to write NCT7201_REG_CONFIGURATION\n");
> > +
> > +     /*
> > +      * After about 25 msecs, the device should be ready and then the Power
> > +      * Up bit will be set to 1. If not, wait for it.
> > +      */
> > +     mdelay(25);
>
> No sleep? Why? Can't you use fsleep()?
>

+ msleep(25);

> > +     err = regmap_read(chip->regmap, NCT7201_REG_BUSY_STATUS, &value);
> > +     if (err < 0)
> > +             return err;
> > +     if (!(value & NCT7201_BIT_PWR_UP))
> > +             return dev_err_probe(&chip->client->dev, -EIO,
>
> Shadowed error code, why?

Do not shadow the return code by -EIO and let the regmap API caller decide.

>
> > +                                  "Failed to power up after reset\n");
> > +
> > +     /* Enable Channel */
> > +     if (chip->num_vin_channels <= 8) {
> > +             data[0] = NCT7201_REG_CHANNEL_ENABLE_1_MASK;
> > +             err = regmap_write(chip->regmap, NCT7201_REG_CHANNEL_ENABLE_1, data[0]);
> > +             if (err < 0)
> > +                     return dev_err_probe(&chip->client->dev, -EIO,
>
> Why error code is shadowed?
>

Do not shadow the return code by -EIO and let the regmap API caller decide.

> > +                                          "Failed to write NCT7201_REG_CHANNEL_ENABLE_1\n");
> > +     } else {
> > +             data[0] = NCT7201_REG_CHANNEL_ENABLE_1_MASK;
> > +             data[1] = NCT7201_REG_CHANNEL_ENABLE_2_MASK;
> > +             err = regmap_bulk_write(chip->regmap, NCT7201_REG_CHANNEL_ENABLE_1,
> > +                                     data, ARRAY_SIZE(data));
> > +             if (err < 0)
> > +                     return dev_err_probe(&chip->client->dev, -EIO,
>
> Ditto.
>
> > +                                          "Failed to write NCT7201_REG_CHANNEL_ENABLE_1 and NCT7201_REG_CHANNEL_ENABLE_2\n");
> > +     }
>
> Just make it 16-bit type, define one value and use just simple English
> in the error message: "Failed to write channel enable mask\n");
>
> Same to all your error messages.
>

We would examine all the error messages in simple English.

> > +     chip->vin_mask = get_unaligned_le16(data);
> > +
> > +     /* Start monitoring if needed */
> > +     err = regmap_read(chip->regmap, NCT7201_REG_CONFIGURATION, &value);
> > +     if (err < 0)
> > +             return dev_err_probe(&chip->client->dev, -EIO,
> > +                                  "Failed to read NCT7201_REG_CONFIGURATION\n");
>
> > +     regmap_set_bits(chip->regmap, NCT7201_REG_CONFIGURATION, NCT7201_BIT_CONFIGURATION_START);
>
> > +     return 0;
>
> No error check? Why?
>

+ err = regmap_set_bits(chip->regmap, NCT7201_REG_CONFIGURATION,
+       NCT7201_BIT_CONFIGURATION_START);
+ if (err)
+ return dev_err_probe(dev, err, "Failed to start monitoring\n");


> > +}
>
> ...
>
> > +static int nct7201_probe(struct i2c_client *client)
> > +{
> > +     const struct nct7201_adc_model_data *model_data;
>
>         struct device *dev = &client->dev;
>
> > +     struct nct7201_chip_info *chip;
> > +     struct iio_dev *indio_dev;
> > +     int ret;
> > +
> > +     model_data = i2c_get_match_data(client);
> > +     if (!model_data)
> > +             return -EINVAL;
>
> ENODEV is more suitable here.
>
+ return -ENODEV

> > +
> > +     indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*chip));
> > +     if (!indio_dev)
> > +             return -ENOMEM;
> > +     chip = iio_priv(indio_dev);
> > +
> > +     chip->regmap = devm_regmap_init_i2c(client, &nct7201_regmap8_config);
> > +     if (IS_ERR(chip->regmap))
> > +             return dev_err_probe(&client->dev, PTR_ERR(chip->regmap),
> > +                                  "Failed to init regmap\n");
> > +
> > +     chip->regmap16 = devm_regmap_init_i2c(client, &nct7201_regmap16_config);
> > +     if (IS_ERR(chip->regmap16))
> > +             return dev_err_probe(&client->dev, PTR_ERR(chip->regmap16),
> > +                                  "Failed to init regmap16\n");
> > +
> > +     chip->num_vin_channels = model_data->num_vin_channels;
>
> > +     chip->client = client;
>
> How exactly is _client_ used elsewhere? Shouldn't it be just a struct device
> pointer?

Yes, it is just a struct device pointer.
In nct7201_init_chip(chip), we would use the chip->client->dev as
dev_err_probe() parameter
>
> > +     ret = nct7201_init_chip(chip);
> > +     if (ret < 0)
>
> Do you expect positive returned values? What is their meaning?
> Why do you skip them?
>

No, we don't expect positive return values.

> > +             return ret;
> > +
> > +     indio_dev->name = model_data->model_name;
> > +     indio_dev->channels = model_data->channels;
> > +     indio_dev->num_channels = model_data->num_channels;
> > +     if (client->irq)
> > +             indio_dev->info = &nct7201_info;
> > +     else
> > +             indio_dev->info = &nct7201_info_no_irq;
> > +     indio_dev->modes = INDIO_DIRECT_MODE;
> > +
> > +     return devm_iio_device_register(&client->dev, indio_dev);
> > +}
>
> --
> With Best Regards,
> Andy Shevchenko
>
>

Re: [PATCH v5 2/2] iio: adc: add support for Nuvoton NCT7201

[Andy Shevchenko]

On Mon, Apr 14, 2025 at 09:40:35PM +0800, Yu-Hsian Yang wrote:
> Andy Shevchenko <andriy.shevchenko@linux.intel.com> 於 2025年4月10日 週四 上午12:19寫道：
> > On Wed, Apr 09, 2025 at 09:23:51AM +0800, Eason Yang wrote:

...

> > Here and elsewhere why ' < 0' is used? Do you expect positive return values
> > from those?
> 
> In regmap_read function, A value of zero will be returned on success,
> a negative errno will be returned in error cases.
> We don't have a positive return case.

So, can we remove ' < 0' parts where they are not required, please?

...

> > > +     chip->client = client;
> >
> > How exactly is _client_ used elsewhere? Shouldn't it be just a struct device
> > pointer?
> 
> Yes, it is just a struct device pointer.
> In nct7201_init_chip(chip), we would use the chip->client->dev as
> dev_err_probe() parameter

Just save there struct device *dev and use chip->dev instead.

-- 
With Best Regards,
Andy Shevchenko