[PATCH v1 2/2] iio: adc: add Nuvoton NCT720x ADC driver

anish kumar yesanishhere at gmail.com
Thu Nov 7 17:13:58 AEDT 2024


On Tue, Nov 5, 2024 at 6:39 PM Eason Yang <j2anfernee at gmail.com> 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 the all 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 support.
>
> Signed-off-by: Eason Yang <j2anfernee at gmail.com>
> ---
>  MAINTAINERS               |   1 +
>  drivers/iio/adc/Kconfig   |   9 +
>  drivers/iio/adc/Makefile  |   1 +
>  drivers/iio/adc/nct720x.c | 617 ++++++++++++++++++++++++++++++++++++++
>  4 files changed, 628 insertions(+)
>  create mode 100644 drivers/iio/adc/nct720x.c
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 68570c58e7aa..9940de0ddca2 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -2753,6 +2753,7 @@ F:        arch/arm/mach-npcm/
>  F:     arch/arm64/boot/dts/nuvoton/
>  F:     drivers/*/*/*npcm*
>  F:     drivers/*/*npcm*
> +F:     drivers/iio/adc/nct720x.c
>  F:     drivers/rtc/rtc-nct3018y.c
>  F:     include/dt-bindings/clock/nuvoton,npcm7xx-clock.h
>  F:     include/dt-bindings/clock/nuvoton,npcm845-clk.h
> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> index 6c4e74420fd2..adbbf0ca6f57 100644
> --- a/drivers/iio/adc/Kconfig
> +++ b/drivers/iio/adc/Kconfig
> @@ -1008,6 +1008,15 @@ config NAU7802
>           To compile this driver as a module, choose M here: the
>           module will be called nau7802.
>
> +config NCT720X
> +       tristate "Nuvoton Instruments NCT7201 and NCT7202 Power Monitor"
> +       depends on 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 nct720x.
> +
>  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 7b91cd98c0e0..f53318e5aa04 100644
> --- a/drivers/iio/adc/Makefile
> +++ b/drivers/iio/adc/Makefile
> @@ -91,6 +91,7 @@ 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-$(CONFIG_NCT720X) += nct720x.o
>  obj-$(CONFIG_NPCM_ADC) += npcm_adc.o
>  obj-$(CONFIG_PAC1921) += pac1921.o
>  obj-$(CONFIG_PAC1934) += pac1934.o
> diff --git a/drivers/iio/adc/nct720x.c b/drivers/iio/adc/nct720x.c
> new file mode 100644
> index 000000000000..e589479fd06e
> --- /dev/null
> +++ b/drivers/iio/adc/nct720x.c
> @@ -0,0 +1,617 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Driver for Nuvoton nct7201 and nct7202 power monitor chips.
> + *
> + * Copyright (c) 2022 Nuvoton Inc.
> + */
> +
> +#include <linux/delay.h>
> +#include <linux/device.h>
> +#include <linux/i2c.h>
> +#include <linux/iio/events.h>
> +#include <linux/iio/iio.h>
> +#include <linux/iio/sysfs.h>
> +#include <linux/init.h>
> +#include <linux/module.h>
> +#include <linux/mutex.h>
> +
> +#define REG_CHIP_ID                    0xFD
> +#define NCT720X_ID                     0xD7
> +#define REG_VENDOR_ID                  0xFE
> +#define NUVOTON_ID                     0x50
> +#define REG_DEVICE_ID                  0xFF
> +#define NCT720X_DEVICE_ID              0x12
> +#define VIN_MAX                                12      /* Counted from 1 */
> +#define NCT7201_VIN_MAX                        8
> +#define NCT7202_VIN_MAX                        12
> +#define NCT720X_IN_SCALING             4995
> +
> +#define REG_INTERRUPT_STATUS_1         0x0C
> +#define REG_INTERRUPT_STATUS_2         0x0D
> +#define REG_VOLT_LOW_BYTE              0x0F
> +#define REG_CONFIGURATION              0x10
> +#define  CONFIGURATION_START           BIT(0)
> +#define  CONFIGURATION_ALERT_MSK       BIT(1)
> +#define  CONFIGURATION_CONV_RATE       BIT(2)
> +#define  CONFIGURATION_INIT            BIT(7)
> +
> +#define REG_ADVANCED_CONFIGURATION     0x11
> +#define  ADVANCED_CONF_MOD_ALERT       BIT(0)
> +#define  ADVANCED_CONF_MOD_STS         BIT(1)
> +#define  ADVANCED_CONF_FAULT_QUEUE     BIT(2)
> +#define  ADVANCED_CONF_EN_DEEP_SHUTDOWN        BIT(4)
> +#define  ADVANCED_CONF_EN_SMB_TIMEOUT  BIT(5)
> +#define  ADVANCED_CONF_MOD_RSTIN       BIT(7)
> +
> +#define REG_CHANNEL_INPUT_MODE         0x12
> +#define REG_CHANNEL_ENABLE_1           0x13
> +#define REG_CHANNEL_ENABLE_2           0x14
> +#define REG_INTERRUPT_MASK_1           0x15
> +#define REG_INTERRUPT_MASK_2           0x16
> +#define REG_BUSY_STATUS                        0x1E
> +#define REG_ONE_SHOT                   0x1F
> +#define REG_SMUS_ADDRESS               0xFC
> +
> +static const u8 REG_VIN[VIN_MAX] = { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05,
> +                                    0x06, 0x07, 0x08, 0x09, 0x0A, 0x0B};
> +static const u8 REG_VIN_HIGH_LIMIT[VIN_MAX] = { 0x20, 0x22, 0x24, 0x26, 0x28, 0x2A,
> +                                               0x2C, 0x2E, 0x30, 0x32, 0x34, 0x36};
> +static const u8 REG_VIN_LOW_LIMIT[VIN_MAX] = { 0x21, 0x23, 0x25, 0x27, 0x29, 0x2B,
> +                                              0x2D, 0x2F, 0x31, 0x33, 0x35, 0x37};
> +static const u8 REG_VIN_HIGH_LIMIT_LSB[VIN_MAX] = { 0x40, 0x42, 0x44, 0x46, 0x48, 0x4A,
> +                                                   0x4C, 0x4E, 0x50, 0x52, 0x54, 0x56};
> +static const u8 REG_VIN_LOW_LIMIT_LSB[VIN_MAX] = { 0x41, 0x43, 0x45, 0x47, 0x49, 0x4B,
> +                                                  0x4D, 0x4F, 0x51, 0x53, 0x55, 0x57};
> +static u8 nct720x_chan_to_index[] = {
> +       0,      /* Not used */
> +       0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11
> +};
> +
> +
> +/* List of supported devices */
> +enum nct720x_chips {
> +       nct7201, nct7202
> +};
> +
> +struct nct720x_chip_info {
> +       struct i2c_client       *client;
> +       enum nct720x_chips      type;
> +       struct mutex            access_lock;    /* for multi-byte read and write operations */
> +       int vin_max;                            /* number of VIN channels */
> +       u32 vin_mask;
> +       bool use_read_byte_vin;
> +};
> +
> +static const struct iio_event_spec nct720x_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 NCT720X_VOLTAGE_CHANNEL(chan, addr)                            \
> +       {                                                               \
> +               .type = IIO_VOLTAGE,                                    \
> +               .indexed = 1,                                           \
> +               .channel = chan,                                        \
> +               .info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),     \
> +               .address = addr,                                        \
> +               .event_spec = nct720x_events,                           \
> +               .num_event_specs = ARRAY_SIZE(nct720x_events),          \
> +       }
> +
> +#define NCT720X_VOLTAGE_CHANNEL_DIFF(chan1, chan2, addr)               \
> +       {                                                               \
> +               .type = IIO_VOLTAGE,                                    \
> +               .indexed = 1,                                           \
> +               .channel = (chan1),                                     \
> +               .channel2 = (chan2),                                    \
> +               .differential = 1,                                      \
> +               .info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),     \
> +               .address = addr,                                        \
> +               .event_spec = nct720x_events,                           \
> +               .num_event_specs = ARRAY_SIZE(nct720x_events),          \
> +       }
> +
> +static const struct iio_chan_spec nct720x_channels[] = {
> +       NCT720X_VOLTAGE_CHANNEL(1, 1),
> +       NCT720X_VOLTAGE_CHANNEL(2, 2),
> +       NCT720X_VOLTAGE_CHANNEL(3, 3),
> +       NCT720X_VOLTAGE_CHANNEL(4, 4),
> +       NCT720X_VOLTAGE_CHANNEL(5, 5),
> +       NCT720X_VOLTAGE_CHANNEL(6, 6),
> +       NCT720X_VOLTAGE_CHANNEL(7, 7),
> +       NCT720X_VOLTAGE_CHANNEL(8, 8),
> +       NCT720X_VOLTAGE_CHANNEL(9, 9),
> +       NCT720X_VOLTAGE_CHANNEL(10, 10),
> +       NCT720X_VOLTAGE_CHANNEL(11, 11),
> +       NCT720X_VOLTAGE_CHANNEL(12, 12),
> +       NCT720X_VOLTAGE_CHANNEL_DIFF(1, 2, 1),
> +       NCT720X_VOLTAGE_CHANNEL_DIFF(3, 4, 3),
> +       NCT720X_VOLTAGE_CHANNEL_DIFF(5, 6, 5),
> +       NCT720X_VOLTAGE_CHANNEL_DIFF(7, 8, 7),
> +       NCT720X_VOLTAGE_CHANNEL_DIFF(9, 10, 9),
> +       NCT720X_VOLTAGE_CHANNEL_DIFF(11, 12, 11),
> +};
> +
> +/* Read 1-byte register. Returns unsigned byte data or -ERRNO on error. */
> +static int nct720x_read_reg(struct nct720x_chip_info *chip, u8 reg)
> +{
> +       struct i2c_client *client = chip->client;
> +
> +       return i2c_smbus_read_byte_data(client, reg);
> +}
> +
> +/* Read 1-byte register. Returns unsigned word data or -ERRNO on error. */
> +static int nct720x_read_word_swapped_reg(struct nct720x_chip_info *chip, u8 reg)
> +{
> +       struct i2c_client *client = chip->client;
> +
> +       return i2c_smbus_read_word_swapped(client, reg);
> +}
> +
> +/*
> + * Read 2-byte register. Returns register in big-endian format or
> + * -ERRNO on error.
> + */
> +static int nct720x_read_reg16(struct nct720x_chip_info *chip, u8 reg)
> +{
> +       struct i2c_client *client = chip->client;
> +       int ret, low;
> +
> +       mutex_lock(&chip->access_lock);
> +       ret = i2c_smbus_read_byte_data(client, reg);
> +       if (ret >= 0) {
> +               low = ret;
> +               ret = i2c_smbus_read_byte_data(client, reg + 1);
> +               if (ret >= 0)
> +                       ret = low | (ret << 8);
> +       }
> +
> +       mutex_unlock(&chip->access_lock);
> +       return ret;
> +}
> +
> +/* Write 1-byte register. Returns 0 or -ERRNO on error. */
> +static int nct720x_write_reg(struct nct720x_chip_info *chip, u8 reg, u8 val)
> +{
> +       struct i2c_client *client = chip->client;
> +       int err;
> +
> +       err = i2c_smbus_write_byte_data(client, reg, val);
> +       /* wait for write command to be finished */
> +       mdelay(10);
> +
> +       return err;
> +}
> +
> +static int nct720x_read_raw(struct iio_dev *indio_dev,
> +                           struct iio_chan_spec const *chan,
> +                           int *val, int *val2, long mask)
> +{
> +       int index = nct720x_chan_to_index[chan->address];
> +       int v1, v2, volt, err;
> +       struct nct720x_chip_info *chip = iio_priv(indio_dev);
> +
> +       if (chan->type != IIO_VOLTAGE)
> +               return -EOPNOTSUPP;
> +
> +       switch (mask) {
> +       case IIO_CHAN_INFO_PROCESSED:
> +               mutex_lock(&chip->access_lock);
> +               if (chip->use_read_byte_vin) {
> +                       /*
> +                        * MNTVIN Low Byte together with MNTVIN High Byte
> +                        * forms the 13-bit count value. If MNTVIN High
> +                        * Byte readout is read successively, the
> +                        * NCT7201/NCT7202 will latch the MNTVIN Low Byte
> +                        * for next read.
> +                        */
> +                       v1 = nct720x_read_reg(chip, REG_VIN[index]);
> +                       if (v1 < 0) {
> +                               err = v1;
> +                               goto abort;
> +                       }
> +
> +                       v2 = nct720x_read_reg(chip, REG_VOLT_LOW_BYTE);
> +                       if (v2 < 0) {
> +                               err = v2;
> +                               goto abort;
> +                       }
> +                       volt = (v1 << 8) | v2;  /* Convert back to 16-bit value */
> +               } else {
> +                       /* NCT7201/NCT7202 also supports read word-size data */
> +                       volt = nct720x_read_word_swapped_reg(chip, REG_VIN[index]);
> +               }
> +
> +               /* Voltage(V) = 13bitCountValue * 0.0004995 */
> +               volt = (volt >> 3) * NCT720X_IN_SCALING;
> +               *val = volt / 10000;
> +               mutex_unlock(&chip->access_lock);
> +               return IIO_VAL_INT;
> +       default:
> +               return -EINVAL;
> +       }
> +abort:
> +       mutex_unlock(&chip->access_lock);
> +       return err;
> +}
> +
> +static int nct720x_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 nct720x_chip_info *chip = iio_priv(indio_dev);
> +       int v1, v2, err;
> +       int volt = 0;
> +       int index = nct720x_chan_to_index[chan->address];
> +
> +       if (chan->type != IIO_VOLTAGE)
> +               return -EOPNOTSUPP;
> +
> +       if (info == IIO_EV_INFO_VALUE) {
> +               if (dir == IIO_EV_DIR_FALLING) {
> +                       if (chip->use_read_byte_vin) {
> +                               /*
> +                                * Low limit VIN Low Byte together with Low limit VIN High Byte
> +                                  forms the 13-bit count value
> +                                */
> +                               mutex_lock(&chip->access_lock);
> +                               v1 = nct720x_read_reg(chip, REG_VIN_LOW_LIMIT[index]);
> +                               if (v1 < 0) {
> +                                       err = v1;
> +                                       goto abort;
> +                               }
> +
> +                               v2 = nct720x_read_reg(chip, REG_VIN_LOW_LIMIT_LSB[index]);
> +                               if (v2 < 0) {
> +                                       err = v2;
> +                                       goto abort;
> +                               }
> +                               mutex_unlock(&chip->access_lock);
> +                               volt = (v1 << 8) | v2;  /* Convert back to 16-bit value */
> +                       } else {
> +                               /* NCT7201/NCT7202 also supports read word-size data */
> +                               volt = nct720x_read_word_swapped_reg(chip,
> +                                       REG_VIN_LOW_LIMIT[index]);
> +                       }
> +               } else {
> +                       if (chip->use_read_byte_vin) {
> +                               /*
> +                                * High limit VIN Low Byte together with high limit VIN High Byte
> +                                * forms the 13-bit count value
> +                                */
> +                               mutex_lock(&chip->access_lock);
> +                               v1 = nct720x_read_reg(chip, REG_VIN_HIGH_LIMIT[index]);
> +                               if (v1 < 0) {
> +                                       err = v1;
> +                                       goto abort;
> +                               }
> +
> +                               v2 = nct720x_read_reg(chip, REG_VIN_HIGH_LIMIT_LSB[index]);
> +                               if (v2 < 0) {
> +                                       err = v2;
> +                                       goto abort;
> +                               }
> +                               mutex_unlock(&chip->access_lock);
> +                               volt = (v1 << 8) | v2;  /* Convert back to 16-bit value */
> +                       } else {
> +                               /* NCT7201/NCT7202 also supports read word-size data */
> +                               volt = nct720x_read_word_swapped_reg(chip,
> +                                       REG_VIN_HIGH_LIMIT[index]);
> +                       }
> +               }
> +       }
> +       /* Voltage(V) = 13bitCountValue * 0.0004995 */
> +       volt = (volt >> 3) * NCT720X_IN_SCALING;
> +       *val = volt / 10000;
> +
> +       return IIO_VAL_INT;
> +abort:
> +       mutex_unlock(&chip->access_lock);
> +       return err;
> +}
> +
> +static int nct720x_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 nct720x_chip_info *chip = iio_priv(indio_dev);
> +       int index, err = 0;
> +       long v1, v2, volt;
> +
> +       index = nct720x_chan_to_index[chan->address];
> +       volt = (val * 10000) / NCT720X_IN_SCALING;
> +       v1 = volt >> 5;
> +       v2 = (volt & 0x1f) << 3;
> +
> +       if (chan->type != IIO_VOLTAGE)
> +               return -EOPNOTSUPP;
> +
> +       if (info == IIO_EV_INFO_VALUE) {
> +               if (dir == IIO_EV_DIR_FALLING) {
> +                       mutex_lock(&chip->access_lock);
> +                       err = nct720x_write_reg(chip, REG_VIN_LOW_LIMIT[index], v1);
> +                       if (err < 0) {
> +                               pr_err("Failed to write REG_VIN%d_LOW_LIMIT\n", index + 1);
> +                               goto abort;
> +                       }
> +
> +                       err = nct720x_write_reg(chip, REG_VIN_LOW_LIMIT_LSB[index], v2);
> +                       if (err < 0) {
> +                               pr_err("Failed to write REG_VIN%d_LOW_LIMIT_LSB\n", index + 1);
> +                               goto abort;
> +                       }
> +               } else {
> +                       mutex_lock(&chip->access_lock);
> +                       err = nct720x_write_reg(chip, REG_VIN_HIGH_LIMIT[index], v1);
> +                       if (err < 0) {
> +                               pr_err("Failed to write REG_VIN%d_HIGH_LIMIT\n", index + 1);
> +                               goto abort;
> +                       }
> +
> +                       err = nct720x_write_reg(chip, REG_VIN_HIGH_LIMIT_LSB[index], v2);
> +                       if (err < 0) {
> +                               pr_err("Failed to write REG_VIN%d_HIGH_LIMIT_LSB\n", index + 1);
> +                               goto abort;
> +                       }
> +               }
> +       }
> +abort:
> +       mutex_unlock(&chip->access_lock);
> +       return err;
> +}
> +
> +static int nct720x_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 nct720x_chip_info *chip = iio_priv(indio_dev);
> +       int index = nct720x_chan_to_index[chan->address];
> +
> +       if (chan->type != IIO_VOLTAGE)
> +               return -EOPNOTSUPP;
> +
> +       return !!(chip->vin_mask & BIT(index));
> +}
> +
> +static int nct720x_write_event_config(struct iio_dev *indio_dev,
> +                                     const struct iio_chan_spec *chan,
> +                                     enum iio_event_type type,
> +                                     enum iio_event_direction dir,
> +                                     int state)
> +{
> +       int err = 0;
> +       struct nct720x_chip_info *chip = iio_priv(indio_dev);
> +       int index = nct720x_chan_to_index[chan->address];
> +       unsigned int mask;
> +
> +       mask = BIT(index);

nitpick:
You can set the mask near to the place where it is used i.e.
just after below if statement and one added advantage will
be in case below "return -EOPNOTSUPP" gets executed,
you don't even have to set mask.

> +
> +       if (chan->type != IIO_VOLTAGE)
> +               return -EOPNOTSUPP;
> +
> +       if (!state && (chip->vin_mask & mask))
> +               chip->vin_mask &= ~mask;
> +       else if (state && !(chip->vin_mask & mask))
> +               chip->vin_mask |= mask;
> +
> +       mutex_lock(&chip->access_lock);
> +
> +       err = nct720x_write_reg(chip, REG_CHANNEL_ENABLE_1, chip->vin_mask & 0xff);
> +       if (err < 0) {
> +               pr_err("Failed to write REG_CHANNEL_ENABLE_1\n");
> +               goto abort;
> +       }
> +
> +       if (chip->type == nct7202) {
> +               err = nct720x_write_reg(chip, REG_CHANNEL_ENABLE_2, chip->vin_mask >> 8);
> +               if (err < 0) {
> +                       pr_err("Failed to write REG_CHANNEL_ENABLE_2\n");
> +                       goto abort;
> +               }
> +       }
> +abort:
> +       mutex_unlock(&chip->access_lock);
> +       return err;
> +}
> +
> +static int nct720x_detect(struct i2c_client *client,
> +                         struct i2c_board_info *info)
> +{
> +       struct i2c_adapter *adapter = client->adapter;
> +
> +       if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA |
> +                                    I2C_FUNC_SMBUS_WORD_DATA))
> +               return -ENODEV;
> +
> +       /* Determine the chip type. */
> +       if (i2c_smbus_read_byte_data(client, REG_VENDOR_ID) != NUVOTON_ID ||
> +           i2c_smbus_read_byte_data(client, REG_CHIP_ID) != NCT720X_ID ||
> +           i2c_smbus_read_byte_data(client, REG_DEVICE_ID) != NCT720X_DEVICE_ID)
> +               return -ENODEV;
> +
> +       strscpy(info->type, "nct720x", I2C_NAME_SIZE);
> +
> +       return 0;
> +}
> +
> +static const struct iio_info nct720x_info = {
> +       .read_raw = &nct720x_read_raw,
> +       .read_event_config = &nct720x_read_event_config,
> +       .write_event_config = &nct720x_write_event_config,
> +       .read_event_value = &nct720x_read_event_value,
> +       .write_event_value = &nct720x_write_event_value,
> +};
> +
> +static const struct i2c_device_id nct720x_id[];
> +
> +static int nct720x_init_chip(struct nct720x_chip_info *chip)
> +{
> +       int value = 0;
> +       int err = 0;

Nit pick:
You don't need to initialize err and value.

> +
> +       /* Initial reset */
> +       err = nct720x_write_reg(chip, REG_CONFIGURATION, CONFIGURATION_INIT);
> +       if (err) {
> +               pr_err("Failed to write REG_CONFIGURATION\n");
> +               return err;
> +       }
> +
> +       /* Enable Channel */
> +       err = nct720x_write_reg(chip, REG_CHANNEL_ENABLE_1, 0xff);
> +       if (err) {
> +               pr_err("Failed to write REG_CHANNEL_ENABLE_1\n");
> +               return err;
> +       }
> +
> +       if (chip->type == nct7202) {
> +               err = nct720x_write_reg(chip, REG_CHANNEL_ENABLE_2, 0xf);
> +               if (err) {
> +                       pr_err("Failed to write REG_CHANNEL_ENABLE_2\n");
> +                       return err;
> +               }
> +       }
> +
> +       value = nct720x_read_reg16(chip, REG_CHANNEL_ENABLE_1);
> +       if (value < 0)
> +               return value;
> +       chip->vin_mask = value;
> +
> +       /* Start monitoring if needed */
> +       value = nct720x_read_reg(chip, REG_CONFIGURATION);
> +       if (value < 0) {
> +               pr_err("Failed to read REG_CONFIGURATION\n");
> +               return value;
> +       }
> +
> +       value |= CONFIGURATION_START;
> +       err = nct720x_write_reg(chip, REG_CONFIGURATION, value);
> +       if (err < 0) {
> +               pr_err("Failed to write REG_CONFIGURATION\n");
> +               return err;
> +       }
> +
> +       return 0;
> +}
> +
> +static int nct720x_probe(struct i2c_client *client)
> +{
> +       const struct i2c_device_id *id = i2c_client_get_device_id(client);
> +       struct nct720x_chip_info *chip;
> +       struct iio_dev *indio_dev;
> +       int ret;
> +       u32 tmp;
> +
> +       indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*chip));
> +       if (!indio_dev)
> +               return -ENOMEM;
> +       chip = iio_priv(indio_dev);
> +
> +       if (client->dev.of_node)
> +               chip->type = (enum nct720x_chips)device_get_match_data(&client->dev);
> +       else
> +               chip->type = i2c_match_id(nct720x_id, client)->driver_data;
> +
> +       chip->vin_max = (chip->type == nct7201) ? NCT7201_VIN_MAX : NCT7202_VIN_MAX;
> +
> +       ret = of_property_read_u32(client->dev.of_node, "read-vin-data-size", &tmp);
> +       if (ret < 0) {
> +               pr_err("read-vin-data-size property not found\n");
> +               return ret;

nit: dev_err_probe

> +       }
> +
> +       if (tmp == 8) {
> +               chip->use_read_byte_vin = true;
> +       } else if (tmp == 16) {
> +               chip->use_read_byte_vin = false;
> +       } else {
> +               pr_err("invalid read-vin-data-size (%d)\n", tmp);
> +               return -EINVAL;

nit: dev_err_probe

> +       }
> +
> +       mutex_init(&chip->access_lock);
> +
> +       /* this is only used for device removal purposes */
> +       i2c_set_clientdata(client, indio_dev);
> +
> +       chip->client = client;
> +
> +       ret = nct720x_init_chip(chip);
> +       if (ret < 0)
> +               return ret;
> +
> +       indio_dev->name = id->name;
> +       indio_dev->channels = nct720x_channels;
> +       indio_dev->num_channels = ARRAY_SIZE(nct720x_channels);
> +       indio_dev->info = &nct720x_info;
> +       indio_dev->modes = INDIO_DIRECT_MODE;
> +
> +       iio_device_register(indio_dev);

devm_iio_device_register?

> +
> +       return 0;
> +}
> +
> +static void nct720x_remove(struct i2c_client *client)
> +{
> +       struct iio_dev *indio_dev = i2c_get_clientdata(client);
> +
> +       iio_device_unregister(indio_dev);

wouldn't need if used devm_ version
> +}
> +
> +static const unsigned short nct720x_address_list[] = {
> +       0x1d, 0x1e, 0x35, 0x36, I2C_CLIENT_END
> +};
> +
> +static const struct i2c_device_id nct720x_id[] = {
> +       { "nct7201", nct7201 },
> +       { "nct7202", nct7202 },
> +       {}
> +};
> +MODULE_DEVICE_TABLE(i2c, nct720x_id);
> +
> +static const struct of_device_id nct720x_of_match[] = {
> +       {
> +               .compatible = "nuvoton,nct7201",
> +               .data = (void *)nct7201
> +       },
> +       {
> +               .compatible = "nuvoton,nct7202",
> +               .data = (void *)nct7202
> +       },
> +       { },
> +};
> +
> +MODULE_DEVICE_TABLE(of, nct720x_of_match);
> +
> +static struct i2c_driver nct720x_driver = {
> +       .driver = {
> +               .name   = "nct720x",
> +               .of_match_table = nct720x_of_match,
> +       },
> +       .probe = nct720x_probe,
> +       .remove = nct720x_remove,
> +       .id_table = nct720x_id,
> +       .detect = nct720x_detect,
> +       .address_list = nct720x_address_list,
> +};
> +
> +module_i2c_driver(nct720x_driver);
> +
> +MODULE_AUTHOR("Eason Yang <YHYANG2 at nuvoton.com>");
> +MODULE_DESCRIPTION("Nuvoton NCT720x voltage monitor driver");
> +MODULE_LICENSE("GPL");
> --
> 2.34.1
>
>


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