diff mbox series

[v1,6/9] hwmon: Add Nuvoton NCT6694 HWMON support

Message ID 20241024085922.133071-7-tmyu0@nuvoton.com
State New
Headers show
Series Add Nuvoton NCT6694 MFD devices | expand

Commit Message

Ming Yu Oct. 24, 2024, 8:59 a.m. UTC
This driver supports Hardware monitor functionality for NCT6694 MFD
device based on USB interface.

Signed-off-by: Ming Yu <tmyu0@nuvoton.com>
---
 MAINTAINERS                   |   1 +
 drivers/hwmon/Kconfig         |  10 +
 drivers/hwmon/Makefile        |   1 +
 drivers/hwmon/nct6694-hwmon.c | 407 ++++++++++++++++++++++++++++++++++
 4 files changed, 419 insertions(+)
 create mode 100644 drivers/hwmon/nct6694-hwmon.c

Comments

Kalesh Anakkur Purayil Oct. 24, 2024, 9:20 a.m. UTC | #1
On Thu, Oct 24, 2024 at 2:33 PM Ming Yu <a0282524688@gmail.com> wrote:
>
> This driver supports Hardware monitor functionality for NCT6694 MFD
> device based on USB interface.
>
> Signed-off-by: Ming Yu <tmyu0@nuvoton.com>
> ---
>  MAINTAINERS                   |   1 +
>  drivers/hwmon/Kconfig         |  10 +
>  drivers/hwmon/Makefile        |   1 +
>  drivers/hwmon/nct6694-hwmon.c | 407 ++++++++++++++++++++++++++++++++++
>  4 files changed, 419 insertions(+)
>  create mode 100644 drivers/hwmon/nct6694-hwmon.c
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 63387c0d4ab6..2aa87ad84156 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -16439,6 +16439,7 @@ M:      Ming Yu <tmyu0@nuvoton.com>
>  L:     linux-kernel@vger.kernel.org
>  S:     Supported
>  F:     drivers/gpio/gpio-nct6694.c
> +F:     drivers/hwmon/nct6694-hwmon.c
>  F:     drivers/i2c/busses/i2c-nct6694.c
>  F:     drivers/mfd/nct6694.c
>  F:     drivers/net/can/nct6694_canfd.c
> diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
> index 08a3c863f80a..740e4afe6582 100644
> --- a/drivers/hwmon/Kconfig
> +++ b/drivers/hwmon/Kconfig
> @@ -1625,6 +1625,16 @@ config SENSORS_NCT6683
>           This driver can also be built as a module. If so, the module
>           will be called nct6683.
>
> +config SENSORS_NCT6694
> +       tristate "Nuvoton NCT6694 Hardware Monitor support"
> +       depends on MFD_NCT6694
> +       help
> +         Say Y here to support Nuvoton NCT6694 hardware monitoring
> +         functionality.
> +
> +         This driver can also be built as a module. If so, the module
> +         will be called nct6694-hwmon.
> +
>  config SENSORS_NCT6775_CORE
>         tristate
>         select REGMAP
> diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
> index 9554d2fdcf7b..729961176d00 100644
> --- a/drivers/hwmon/Makefile
> +++ b/drivers/hwmon/Makefile
> @@ -167,6 +167,7 @@ obj-$(CONFIG_SENSORS_MLXREG_FAN) += mlxreg-fan.o
>  obj-$(CONFIG_SENSORS_MENF21BMC_HWMON) += menf21bmc_hwmon.o
>  obj-$(CONFIG_SENSORS_MR75203)  += mr75203.o
>  obj-$(CONFIG_SENSORS_NCT6683)  += nct6683.o
> +obj-$(CONFIG_SENSORS_NCT6694)  += nct6694-hwmon.o
>  obj-$(CONFIG_SENSORS_NCT6775_CORE) += nct6775-core.o
>  nct6775-objs                   := nct6775-platform.o
>  obj-$(CONFIG_SENSORS_NCT6775)  += nct6775.o
> diff --git a/drivers/hwmon/nct6694-hwmon.c b/drivers/hwmon/nct6694-hwmon.c
> new file mode 100644
> index 000000000000..7d7d22a650b0
> --- /dev/null
> +++ b/drivers/hwmon/nct6694-hwmon.c
> @@ -0,0 +1,407 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Nuvoton NCT6694 HWMON driver based on USB interface.
> + *
> + * Copyright (C) 2024 Nuvoton Technology Corp.
> + */
> +
> +#include <linux/slab.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/hwmon.h>
> +#include <linux/platform_device.h>
> +#include <linux/mfd/nct6694.h>
> +
> +#define DRVNAME "nct6694-hwmon"
> +
> +/* Host interface */
> +#define REQUEST_RPT_MOD                        0xFF
> +#define REQUEST_HWMON_MOD              0x00
> +
> +/* Report Channel */
> +#define HWMON_FIN_IDX(x)               (0x50 + ((x) * 2))
> +#define HWMON_FIN_STS(x)               (0x6E + (x))
> +#define HWMON_PWM_IDX(x)               (0x70 + (x))
> +
> +/* Message Channel*/
> +/* Command 00h */
> +#define REQUEST_HWMON_CMD0_LEN         0x40
> +#define REQUEST_HWMON_CMD0_OFFSET      0x0000  /* OFFSET = SEL|CMD */
> +#define HWMON_FIN_EN(x)                        (0x04 + (x))
> +#define HWMON_PWM_FREQ_IDX(x)          (0x30 + (x))
> +/* Command 02h */
> +#define REQUEST_HWMON_CMD2_LEN         0x90
> +#define REQUEST_HWMON_CMD2_OFFSET      0x0002  /* OFFSET = SEL|CMD */
> +#define HWMON_SMI_CTRL_IDX             0x00
> +#define HWMON_FIN_LIMIT_IDX(x)         (0x70 + ((x) * 2))
> +#define HWMON_CMD2_HYST_MASK           0x1F
> +/* Command 03h */
> +#define REQUEST_HWMON_CMD3_LEN         0x08
> +#define REQUEST_HWMON_CMD3_OFFSET      0x0003  /* OFFSET = SEL|CMD */
> +
> +struct nct6694_hwmon_data {
> +       struct nct6694 *nct6694;
> +
> +       /* Make sure read & write commands are consecutive */
> +       struct mutex hwmon_lock;
> +};
> +
> +#define NCT6694_HWMON_FAN_CONFIG (HWMON_F_ENABLE | HWMON_F_INPUT | \
> +                                 HWMON_F_MIN | HWMON_F_MIN_ALARM)
> +#define NCT6694_HWMON_PWM_CONFIG (HWMON_PWM_INPUT | HWMON_PWM_FREQ)
> +
> +static const struct hwmon_channel_info *nct6694_info[] = {
> +       HWMON_CHANNEL_INFO(fan,
> +                          NCT6694_HWMON_FAN_CONFIG,    /* FIN0 */
> +                          NCT6694_HWMON_FAN_CONFIG,    /* FIN1 */
> +                          NCT6694_HWMON_FAN_CONFIG,    /* FIN2 */
> +                          NCT6694_HWMON_FAN_CONFIG,    /* FIN3 */
> +                          NCT6694_HWMON_FAN_CONFIG,    /* FIN4 */
> +                          NCT6694_HWMON_FAN_CONFIG,    /* FIN5 */
> +                          NCT6694_HWMON_FAN_CONFIG,    /* FIN6 */
> +                          NCT6694_HWMON_FAN_CONFIG,    /* FIN7 */
> +                          NCT6694_HWMON_FAN_CONFIG,    /* FIN8 */
> +                          NCT6694_HWMON_FAN_CONFIG),   /* FIN9 */
> +
> +       HWMON_CHANNEL_INFO(pwm,
> +                          NCT6694_HWMON_PWM_CONFIG,    /* PWM0 */
> +                          NCT6694_HWMON_PWM_CONFIG,    /* PWM1 */
> +                          NCT6694_HWMON_PWM_CONFIG,    /* PWM2 */
> +                          NCT6694_HWMON_PWM_CONFIG,    /* PWM3 */
> +                          NCT6694_HWMON_PWM_CONFIG,    /* PWM4 */
> +                          NCT6694_HWMON_PWM_CONFIG,    /* PWM5 */
> +                          NCT6694_HWMON_PWM_CONFIG,    /* PWM6 */
> +                          NCT6694_HWMON_PWM_CONFIG,    /* PWM7 */
> +                          NCT6694_HWMON_PWM_CONFIG,    /* PWM8 */
> +                          NCT6694_HWMON_PWM_CONFIG),   /* PWM9 */
> +       NULL
> +};
> +
> +static int nct6694_fan_read(struct device *dev, u32 attr, int channel,
> +                           long *val)
> +{
> +       struct nct6694_hwmon_data *data = dev_get_drvdata(dev);
> +       unsigned char buf[2];
> +       int ret;
> +
> +       switch (attr) {
> +       case hwmon_fan_enable:
> +               ret = nct6694_read_msg(data->nct6694, REQUEST_HWMON_MOD,
> +                                      REQUEST_HWMON_CMD0_OFFSET,
> +                                      REQUEST_HWMON_CMD0_LEN,
> +                                      HWMON_FIN_EN(channel / 8),
> +                                      1, buf);
> +               if (ret)
> +                       return -EINVAL;
> +
> +               *val = buf[0] & BIT(channel % 8) ? 1 : 0;
> +
> +               break;
> +
> +       case hwmon_fan_input:
> +               ret = nct6694_read_msg(data->nct6694, REQUEST_RPT_MOD,
> +                                      HWMON_FIN_IDX(channel), 2, 0,
> +                                      2, buf);
> +               if (ret)
> +                       return -EINVAL;
> +
> +               *val = (buf[1] | (buf[0] << 8)) & 0xFFFF;
> +
> +               break;
> +
> +       case hwmon_fan_min:
> +               ret = nct6694_read_msg(data->nct6694, REQUEST_HWMON_MOD,
> +                                      REQUEST_HWMON_CMD2_OFFSET,
> +                                      REQUEST_HWMON_CMD2_LEN,
> +                                      HWMON_FIN_LIMIT_IDX(channel),
> +                                      2, buf);
> +               if (ret)
> +                       return -EINVAL;
> +
> +               *val = (buf[1] | (buf[0] << 8)) & 0xFFFF;
> +
> +               break;
> +
> +       case hwmon_fan_min_alarm:
> +               ret = nct6694_read_msg(data->nct6694, REQUEST_RPT_MOD,
> +                                      HWMON_FIN_STS(channel / 8),
> +                                      1, 0, 1, buf);
> +               if (ret)
> +                       return -EINVAL;
> +
> +               *val = buf[0] & BIT(channel % 8);
> +
> +               break;
> +
> +       default:
> +               return -EOPNOTSUPP;
> +       }
> +
> +       return 0;
> +}
> +
> +static int nct6694_pwm_read(struct device *dev, u32 attr, int channel,
> +                           long *val)
> +{
> +       struct nct6694_hwmon_data *data = dev_get_drvdata(dev);
> +       unsigned char buf;
> +       int ret;
> +
> +       switch (attr) {
> +       case hwmon_pwm_input:
> +               ret = nct6694_read_msg(data->nct6694, REQUEST_RPT_MOD,
> +                                      HWMON_PWM_IDX(channel),
> +                                      1, 0, 1, &buf);
> +               if (ret)
> +                       return -EINVAL;
> +
> +               *val = buf;
> +
> +               break;
> +       case hwmon_pwm_freq:
> +               ret = nct6694_read_msg(data->nct6694, REQUEST_HWMON_MOD,
> +                                      REQUEST_HWMON_CMD0_OFFSET,
> +                                      REQUEST_HWMON_CMD0_LEN,
> +                                      HWMON_PWM_FREQ_IDX(channel),
> +                                      1, &buf);
> +               if (ret)
> +                       return -EINVAL;
> +
> +               *val = buf * 25000 / 255;
> +
> +               break;
> +
> +       default:
> +               return -EOPNOTSUPP;
> +       }
> +
> +       return 0;
> +}
> +
> +static int nct6694_fan_write(struct device *dev, u32 attr, int channel,
> +                            long val)
> +{
> +       struct nct6694_hwmon_data *data = dev_get_drvdata(dev);
> +       unsigned char enable_buf[REQUEST_HWMON_CMD0_LEN] = {0};
[Kalesh] Please try to maintain RCT order for variable declaration
> +       unsigned char buf[REQUEST_HWMON_CMD2_LEN] = {0};
> +       u16 fan_val = (u16)val;
> +       int ret;
> +
> +       switch (attr) {
> +       case hwmon_fan_enable:
> +               mutex_lock(&data->hwmon_lock);
> +               ret = nct6694_read_msg(data->nct6694, REQUEST_HWMON_MOD,
> +                                      REQUEST_HWMON_CMD0_OFFSET,
> +                                      REQUEST_HWMON_CMD0_LEN, 0,
> +                                      REQUEST_HWMON_CMD0_LEN,
> +                                      enable_buf);
> +               if (ret)
> +                       goto err;
> +
> +               if (val)
> +                       enable_buf[HWMON_FIN_EN(channel / 8)] |= BIT(channel % 8);
> +               else
> +                       enable_buf[HWMON_FIN_EN(channel / 8)] &= ~BIT(channel % 8);
> +
> +               ret = nct6694_write_msg(data->nct6694, REQUEST_HWMON_MOD,
> +                                       REQUEST_HWMON_CMD0_OFFSET,
> +                                       REQUEST_HWMON_CMD0_LEN, enable_buf);
> +               if (ret)
> +                       goto err;
> +
> +               break;
> +
> +       case hwmon_fan_min:
> +               mutex_lock(&data->hwmon_lock);
> +               ret = nct6694_read_msg(data->nct6694, REQUEST_HWMON_MOD,
> +                                      REQUEST_HWMON_CMD2_OFFSET,
> +                                      REQUEST_HWMON_CMD2_LEN, 0,
> +                                      REQUEST_HWMON_CMD2_LEN, buf);
> +               if (ret)
> +                       goto err;
> +
> +               buf[HWMON_FIN_LIMIT_IDX(channel)] = (u8)((fan_val >> 8) & 0xFF);
> +               buf[HWMON_FIN_LIMIT_IDX(channel) + 1] = (u8)(fan_val & 0xFF);
> +               ret = nct6694_write_msg(data->nct6694, REQUEST_HWMON_MOD,
> +                                       REQUEST_HWMON_CMD2_OFFSET,
> +                                       REQUEST_HWMON_CMD2_LEN, buf);
> +               if (ret)
> +                       goto err;
> +
> +               break;
> +
> +       default:
> +               ret = -EOPNOTSUPP;
[Kalesh] If you initialize "ret = -EOPNOTSUPP;" during declararion,
you can just break from here.
> +               goto err;
> +       }
> +
> +err:
> +       mutex_unlock(&data->hwmon_lock);
> +       return ret;
> +}
> +
> +static int nct6694_read(struct device *dev, enum hwmon_sensor_types type,
> +                       u32 attr, int channel, long *val)
> +{
> +       switch (type) {
> +       case hwmon_fan: /* in RPM */
> +               return nct6694_fan_read(dev, attr, channel, val);
> +
> +       case hwmon_pwm: /* in value 0~255 */
> +               return nct6694_pwm_read(dev, attr, channel, val);
> +
> +       default:
> +               return -EOPNOTSUPP;
> +       }
> +
> +       return 0;
> +}
> +
> +static int nct6694_write(struct device *dev, enum hwmon_sensor_types type,
> +                        u32 attr, int channel, long val)
> +{
> +       switch (type) {
> +       case hwmon_fan:
> +               return nct6694_fan_write(dev, attr, channel, val);
> +       default:
> +               return -EOPNOTSUPP;
> +       }
[Kalesh] You can use simple if condition here than a switch like:
if (type != hwmon_fan)
         return -EOPNOTSUPP;
return nct6694_fan_write(dev, attr, channel, val);
> +
> +       return 0;
> +}
> +
> +static umode_t nct6694_is_visible(const void *data, enum hwmon_sensor_types type,
> +                                 u32 attr, int channel)
> +{
> +       switch (type) {
> +       case hwmon_fan:
> +               switch (attr) {
> +               case hwmon_fan_enable:
> +               case hwmon_fan_min:
> +                       return 0644;
[Kalesh] I think there is no need to leave a new line in between cases
> +
> +               case hwmon_fan_input:
> +               case hwmon_fan_min_alarm:
> +                       return 0444;
> +
> +               default:
> +                       return 0;
> +               }
> +
> +       case hwmon_pwm:
> +               switch (attr) {
> +               case hwmon_pwm_input:
> +               case hwmon_pwm_freq:
> +                       return 0444;
> +               default:
> +                       return 0;
> +               }
> +
> +       default:
> +               return 0;
> +       }
> +
> +       return 0;
[Kalesh] This return statement looks redundant as the execution never
reaches here. Same comment applies to other functions above as well.
> +}
> +
> +static const struct hwmon_ops nct6694_hwmon_ops = {
> +       .is_visible = nct6694_is_visible,
> +       .read = nct6694_read,
> +       .write = nct6694_write,
> +};
> +
> +static const struct hwmon_chip_info nct6694_chip_info = {
> +       .ops = &nct6694_hwmon_ops,
> +       .info = nct6694_info,
> +};
> +
> +static int nct6694_hwmon_init(struct nct6694_hwmon_data *data)
> +{
> +       unsigned char buf[REQUEST_HWMON_CMD2_LEN] = {0};
> +       int ret;
> +
> +       /* Set Fan input Real Time alarm mode */
> +       mutex_lock(&data->hwmon_lock);
> +       ret = nct6694_read_msg(data->nct6694, REQUEST_HWMON_MOD,
> +                              REQUEST_HWMON_CMD2_OFFSET,
> +                              REQUEST_HWMON_CMD2_LEN, 0,
> +                              REQUEST_HWMON_CMD2_LEN, buf);
> +       if (ret)
> +               goto err;
[Kalesh] It would be better to rename the label as "unlock". Same
comment on other functions as well.
> +
> +       buf[HWMON_SMI_CTRL_IDX] = 0x02;
> +
> +       ret = nct6694_write_msg(data->nct6694, REQUEST_HWMON_MOD,
> +                               REQUEST_HWMON_CMD2_OFFSET,
> +                               REQUEST_HWMON_CMD2_LEN, buf);
> +       if (ret)
> +               goto err;
> +
> +err:
> +       mutex_unlock(&data->hwmon_lock);
> +       return ret;
> +}
> +
> +static int nct6694_hwmon_probe(struct platform_device *pdev)
> +{
> +       struct nct6694_hwmon_data *data;
> +       struct nct6694 *nct6694 = dev_get_drvdata(pdev->dev.parent);
> +       struct device *hwmon_dev;
> +       int ret;
> +
> +       data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
> +       if (!data)
> +               return -ENOMEM;
> +
> +       data->nct6694 = nct6694;
> +       mutex_init(&data->hwmon_lock);
> +       platform_set_drvdata(pdev, data);
> +
> +       ret = nct6694_hwmon_init(data);
> +       if (ret)
> +               return -EIO;
> +
> +       /* Register hwmon device to HWMON framework */
> +       hwmon_dev = devm_hwmon_device_register_with_info(&pdev->dev,
> +                                                        "nct6694", data,
> +                                                        &nct6694_chip_info,
> +                                                        NULL);
> +       if (IS_ERR(hwmon_dev)) {
> +               dev_err(&pdev->dev, "%s: Failed to register hwmon device!\n",
> +                       __func__);
> +               return PTR_ERR(hwmon_dev);
> +       }
> +
> +       return 0;
> +}
> +
> +static struct platform_driver nct6694_hwmon_driver = {
> +       .driver = {
> +               .name   = DRVNAME,
> +       },
> +       .probe          = nct6694_hwmon_probe,
> +};
> +
> +static int __init nct6694_init(void)
> +{
> +       int err;
> +
> +       err = platform_driver_register(&nct6694_hwmon_driver);
> +       if (!err) {
> +               if (err)
[Kalesh] This whole check looks strange. You can simplify this function as:
return platform_driver_register(&nct6694_hwmon_driver);
> +                       platform_driver_unregister(&nct6694_hwmon_driver);
> +       }
> +
> +       return err;
> +}
> +subsys_initcall(nct6694_init);
> +
> +static void __exit nct6694_exit(void)
> +{
> +       platform_driver_unregister(&nct6694_hwmon_driver);
> +}
> +module_exit(nct6694_exit);
> +
> +MODULE_DESCRIPTION("USB-HWMON driver for NCT6694");
> +MODULE_AUTHOR("Ming Yu <tmyu0@nuvoton.com>");
> +MODULE_LICENSE("GPL");
> --
> 2.34.1
>
>
Guenter Roeck Oct. 24, 2024, 3:03 p.m. UTC | #2
On 10/24/24 01:59, Ming Yu wrote:
> This driver supports Hardware monitor functionality for NCT6694 MFD
> device based on USB interface.
> 
> Signed-off-by: Ming Yu <tmyu0@nuvoton.com>
> ---
>   MAINTAINERS                   |   1 +
>   drivers/hwmon/Kconfig         |  10 +
>   drivers/hwmon/Makefile        |   1 +
>   drivers/hwmon/nct6694-hwmon.c | 407 ++++++++++++++++++++++++++++++++++
>   4 files changed, 419 insertions(+)
>   create mode 100644 drivers/hwmon/nct6694-hwmon.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 63387c0d4ab6..2aa87ad84156 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -16439,6 +16439,7 @@ M:	Ming Yu <tmyu0@nuvoton.com>
>   L:	linux-kernel@vger.kernel.org
>   S:	Supported
>   F:	drivers/gpio/gpio-nct6694.c
> +F:	drivers/hwmon/nct6694-hwmon.c
>   F:	drivers/i2c/busses/i2c-nct6694.c
>   F:	drivers/mfd/nct6694.c
>   F:	drivers/net/can/nct6694_canfd.c
> diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
> index 08a3c863f80a..740e4afe6582 100644
> --- a/drivers/hwmon/Kconfig
> +++ b/drivers/hwmon/Kconfig
> @@ -1625,6 +1625,16 @@ config SENSORS_NCT6683
>   	  This driver can also be built as a module. If so, the module
>   	  will be called nct6683.
>   
> +config SENSORS_NCT6694
> +	tristate "Nuvoton NCT6694 Hardware Monitor support"
> +	depends on MFD_NCT6694
> +	help
> +	  Say Y here to support Nuvoton NCT6694 hardware monitoring
> +	  functionality.
> +
> +	  This driver can also be built as a module. If so, the module
> +	  will be called nct6694-hwmon.
> +
>   config SENSORS_NCT6775_CORE
>   	tristate
>   	select REGMAP
> diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
> index 9554d2fdcf7b..729961176d00 100644
> --- a/drivers/hwmon/Makefile
> +++ b/drivers/hwmon/Makefile
> @@ -167,6 +167,7 @@ obj-$(CONFIG_SENSORS_MLXREG_FAN) += mlxreg-fan.o
>   obj-$(CONFIG_SENSORS_MENF21BMC_HWMON) += menf21bmc_hwmon.o
>   obj-$(CONFIG_SENSORS_MR75203)	+= mr75203.o
>   obj-$(CONFIG_SENSORS_NCT6683)	+= nct6683.o
> +obj-$(CONFIG_SENSORS_NCT6694)	+= nct6694-hwmon.o
>   obj-$(CONFIG_SENSORS_NCT6775_CORE) += nct6775-core.o
>   nct6775-objs			:= nct6775-platform.o
>   obj-$(CONFIG_SENSORS_NCT6775)	+= nct6775.o
> diff --git a/drivers/hwmon/nct6694-hwmon.c b/drivers/hwmon/nct6694-hwmon.c
> new file mode 100644
> index 000000000000..7d7d22a650b0
> --- /dev/null
> +++ b/drivers/hwmon/nct6694-hwmon.c
> @@ -0,0 +1,407 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Nuvoton NCT6694 HWMON driver based on USB interface.
> + *
> + * Copyright (C) 2024 Nuvoton Technology Corp.
> + */
> +
> +#include <linux/slab.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/hwmon.h>
> +#include <linux/platform_device.h>
> +#include <linux/mfd/nct6694.h>
> +
> +#define DRVNAME "nct6694-hwmon"
> +
> +/* Host interface */
> +#define REQUEST_RPT_MOD			0xFF
> +#define REQUEST_HWMON_MOD		0x00
> +
> +/* Report Channel */
> +#define HWMON_FIN_IDX(x)		(0x50 + ((x) * 2))
> +#define HWMON_FIN_STS(x)		(0x6E + (x))
> +#define HWMON_PWM_IDX(x)		(0x70 + (x))
> +
> +/* Message Channel*/
> +/* Command 00h */
> +#define REQUEST_HWMON_CMD0_LEN		0x40
> +#define REQUEST_HWMON_CMD0_OFFSET	0x0000	/* OFFSET = SEL|CMD */
> +#define HWMON_FIN_EN(x)			(0x04 + (x))
> +#define HWMON_PWM_FREQ_IDX(x)		(0x30 + (x))
> +/* Command 02h */
> +#define REQUEST_HWMON_CMD2_LEN		0x90
> +#define REQUEST_HWMON_CMD2_OFFSET	0x0002	/* OFFSET = SEL|CMD */
> +#define HWMON_SMI_CTRL_IDX		0x00
> +#define HWMON_FIN_LIMIT_IDX(x)		(0x70 + ((x) * 2))
> +#define HWMON_CMD2_HYST_MASK		0x1F
> +/* Command 03h */
> +#define REQUEST_HWMON_CMD3_LEN		0x08
> +#define REQUEST_HWMON_CMD3_OFFSET	0x0003	/* OFFSET = SEL|CMD */
> +
> +struct nct6694_hwmon_data {
> +	struct nct6694 *nct6694;
> +
> +	/* Make sure read & write commands are consecutive */
> +	struct mutex hwmon_lock;
> +};
> +
> +#define NCT6694_HWMON_FAN_CONFIG (HWMON_F_ENABLE | HWMON_F_INPUT | \
> +				  HWMON_F_MIN | HWMON_F_MIN_ALARM)
> +#define NCT6694_HWMON_PWM_CONFIG (HWMON_PWM_INPUT | HWMON_PWM_FREQ)
> +
> +static const struct hwmon_channel_info *nct6694_info[] = {
> +	HWMON_CHANNEL_INFO(fan,
> +			   NCT6694_HWMON_FAN_CONFIG,	/* FIN0 */
> +			   NCT6694_HWMON_FAN_CONFIG,	/* FIN1 */
> +			   NCT6694_HWMON_FAN_CONFIG,	/* FIN2 */
> +			   NCT6694_HWMON_FAN_CONFIG,	/* FIN3 */
> +			   NCT6694_HWMON_FAN_CONFIG,	/* FIN4 */
> +			   NCT6694_HWMON_FAN_CONFIG,	/* FIN5 */
> +			   NCT6694_HWMON_FAN_CONFIG,	/* FIN6 */
> +			   NCT6694_HWMON_FAN_CONFIG,	/* FIN7 */
> +			   NCT6694_HWMON_FAN_CONFIG,	/* FIN8 */
> +			   NCT6694_HWMON_FAN_CONFIG),	/* FIN9 */
> +
> +	HWMON_CHANNEL_INFO(pwm,
> +			   NCT6694_HWMON_PWM_CONFIG,	/* PWM0 */
> +			   NCT6694_HWMON_PWM_CONFIG,	/* PWM1 */
> +			   NCT6694_HWMON_PWM_CONFIG,	/* PWM2 */
> +			   NCT6694_HWMON_PWM_CONFIG,	/* PWM3 */
> +			   NCT6694_HWMON_PWM_CONFIG,	/* PWM4 */
> +			   NCT6694_HWMON_PWM_CONFIG,	/* PWM5 */
> +			   NCT6694_HWMON_PWM_CONFIG,	/* PWM6 */
> +			   NCT6694_HWMON_PWM_CONFIG,	/* PWM7 */
> +			   NCT6694_HWMON_PWM_CONFIG,	/* PWM8 */
> +			   NCT6694_HWMON_PWM_CONFIG),	/* PWM9 */
> +	NULL
> +};
> +
> +static int nct6694_fan_read(struct device *dev, u32 attr, int channel,
> +			    long *val)
> +{
> +	struct nct6694_hwmon_data *data = dev_get_drvdata(dev);
> +	unsigned char buf[2];
> +	int ret;
> +
> +	switch (attr) {
> +	case hwmon_fan_enable:
> +		ret = nct6694_read_msg(data->nct6694, REQUEST_HWMON_MOD,
> +				       REQUEST_HWMON_CMD0_OFFSET,
> +				       REQUEST_HWMON_CMD0_LEN,
> +				       HWMON_FIN_EN(channel / 8),
> +				       1, buf);
> +		if (ret)
> +			return -EINVAL;

Do not overwrite error return values.

> +
> +		*val = buf[0] & BIT(channel % 8) ? 1 : 0;
> +
> +		break;
> +
> +	case hwmon_fan_input:
> +		ret = nct6694_read_msg(data->nct6694, REQUEST_RPT_MOD,
> +				       HWMON_FIN_IDX(channel), 2, 0,
> +				       2, buf);
> +		if (ret)
> +			return -EINVAL;
> +
> +		*val = (buf[1] | (buf[0] << 8)) & 0xFFFF;
> +
> +		break;
> +
> +	case hwmon_fan_min:
> +		ret = nct6694_read_msg(data->nct6694, REQUEST_HWMON_MOD,
> +				       REQUEST_HWMON_CMD2_OFFSET,
> +				       REQUEST_HWMON_CMD2_LEN,
> +				       HWMON_FIN_LIMIT_IDX(channel),
> +				       2, buf);
> +		if (ret)
> +			return -EINVAL;
> +
> +		*val = (buf[1] | (buf[0] << 8)) & 0xFFFF;
> +
> +		break;
> +
> +	case hwmon_fan_min_alarm:
> +		ret = nct6694_read_msg(data->nct6694, REQUEST_RPT_MOD,
> +				       HWMON_FIN_STS(channel / 8),
> +				       1, 0, 1, buf);
> +		if (ret)
> +			return -EINVAL;
> +
> +		*val = buf[0] & BIT(channel % 8);
> +
> +		break;
> +
> +	default:
> +		return -EOPNOTSUPP;
> +	}
> +
> +	return 0;
> +}
> +
> +static int nct6694_pwm_read(struct device *dev, u32 attr, int channel,
> +			    long *val)
> +{
> +	struct nct6694_hwmon_data *data = dev_get_drvdata(dev);
> +	unsigned char buf;
> +	int ret;
> +
> +	switch (attr) {
> +	case hwmon_pwm_input:
> +		ret = nct6694_read_msg(data->nct6694, REQUEST_RPT_MOD,
> +				       HWMON_PWM_IDX(channel),
> +				       1, 0, 1, &buf);
> +		if (ret)
> +			return -EINVAL;
> +
> +		*val = buf;
> +
> +		break;
> +	case hwmon_pwm_freq:
> +		ret = nct6694_read_msg(data->nct6694, REQUEST_HWMON_MOD,
> +				       REQUEST_HWMON_CMD0_OFFSET,
> +				       REQUEST_HWMON_CMD0_LEN,
> +				       HWMON_PWM_FREQ_IDX(channel),
> +				       1, &buf);
> +		if (ret)
> +			return -EINVAL;
> +
> +		*val = buf * 25000 / 255;
> +
> +		break;
> +
> +	default:
> +		return -EOPNOTSUPP;
> +	}
> +
> +	return 0;
> +}
> +
> +static int nct6694_fan_write(struct device *dev, u32 attr, int channel,
> +			     long val)
> +{
> +	struct nct6694_hwmon_data *data = dev_get_drvdata(dev);
> +	unsigned char enable_buf[REQUEST_HWMON_CMD0_LEN] = {0};
> +	unsigned char buf[REQUEST_HWMON_CMD2_LEN] = {0};
> +	u16 fan_val = (u16)val;

This is wrong. It will result in overflows/underflows if out of range
values are provided, and the driver should not write 0 if the user
writes 65536. You need to use clamp_val() instead. For values with
well defined range (specifically hwmon_fan_enable) you need to validate
the parameter, not just take it as boolean.

> +	int ret;
> +
> +	switch (attr) {
> +	case hwmon_fan_enable:
> +		mutex_lock(&data->hwmon_lock);
> +		ret = nct6694_read_msg(data->nct6694, REQUEST_HWMON_MOD,
> +				       REQUEST_HWMON_CMD0_OFFSET,
> +				       REQUEST_HWMON_CMD0_LEN, 0,
> +				       REQUEST_HWMON_CMD0_LEN,
> +				       enable_buf);
> +		if (ret)
> +			goto err;
> +
> +		if (val)
> +			enable_buf[HWMON_FIN_EN(channel / 8)] |= BIT(channel % 8);
> +		else
> +			enable_buf[HWMON_FIN_EN(channel / 8)] &= ~BIT(channel % 8);
> +
> +		ret = nct6694_write_msg(data->nct6694, REQUEST_HWMON_MOD,
> +					REQUEST_HWMON_CMD0_OFFSET,
> +					REQUEST_HWMON_CMD0_LEN, enable_buf);
> +		if (ret)
> +			goto err;
> +
> +		break;
> +
> +	case hwmon_fan_min:
> +		mutex_lock(&data->hwmon_lock);
> +		ret = nct6694_read_msg(data->nct6694, REQUEST_HWMON_MOD,
> +				       REQUEST_HWMON_CMD2_OFFSET,
> +				       REQUEST_HWMON_CMD2_LEN, 0,
> +				       REQUEST_HWMON_CMD2_LEN, buf);
> +		if (ret)
> +			goto err;
> +
> +		buf[HWMON_FIN_LIMIT_IDX(channel)] = (u8)((fan_val >> 8) & 0xFF);
> +		buf[HWMON_FIN_LIMIT_IDX(channel) + 1] = (u8)(fan_val & 0xFF);
> +		ret = nct6694_write_msg(data->nct6694, REQUEST_HWMON_MOD,
> +					REQUEST_HWMON_CMD2_OFFSET,
> +					REQUEST_HWMON_CMD2_LEN, buf);
> +		if (ret)
> +			goto err;
> +
> +		break;

The error handler goto and the break accomplish exactly the same,
thus the conditional goto is pointless.

> +
> +	default:
> +		ret = -EOPNOTSUPP;
> +		goto err;

As mentioned in my other reply, the lock is not acquired here,
causing an unbalanced unlock.

> +	}
> +
> +err:
> +	mutex_unlock(&data->hwmon_lock);
> +	return ret;
> +}
> +
> +static int nct6694_read(struct device *dev, enum hwmon_sensor_types type,
> +			u32 attr, int channel, long *val)
> +{
> +	switch (type) {
> +	case hwmon_fan:	/* in RPM */
> +		return nct6694_fan_read(dev, attr, channel, val);
> +
> +	case hwmon_pwm:	/* in value 0~255 */
> +		return nct6694_pwm_read(dev, attr, channel, val);
> +
> +	default:
> +		return -EOPNOTSUPP;
> +	}
> +
> +	return 0;

Unnecessary return statement. Also seen elsewhere.

> +}
> +
> +static int nct6694_write(struct device *dev, enum hwmon_sensor_types type,
> +			 u32 attr, int channel, long val)
> +{
> +	switch (type) {
> +	case hwmon_fan:
> +		return nct6694_fan_write(dev, attr, channel, val);
> +	default:
> +		return -EOPNOTSUPP;
> +	}
> +
> +	return 0;
> +}
> +
> +static umode_t nct6694_is_visible(const void *data, enum hwmon_sensor_types type,
> +				  u32 attr, int channel)
> +{
> +	switch (type) {
> +	case hwmon_fan:
> +		switch (attr) {
> +		case hwmon_fan_enable:
> +		case hwmon_fan_min:
> +			return 0644;
> +
> +		case hwmon_fan_input:
> +		case hwmon_fan_min_alarm:
> +			return 0444;
> +
> +		default:
> +			return 0;
> +		}
> +
> +	case hwmon_pwm:
> +		switch (attr) {
> +		case hwmon_pwm_input:
> +		case hwmon_pwm_freq:
> +			return 0444;
> +		default:
> +			return 0;
> +		}
> +
> +	default:
> +		return 0;
> +	}
> +
> +	return 0;
> +}
> +
> +static const struct hwmon_ops nct6694_hwmon_ops = {
> +	.is_visible = nct6694_is_visible,
> +	.read = nct6694_read,
> +	.write = nct6694_write,
> +};
> +
> +static const struct hwmon_chip_info nct6694_chip_info = {
> +	.ops = &nct6694_hwmon_ops,
> +	.info = nct6694_info,
> +};
> +
> +static int nct6694_hwmon_init(struct nct6694_hwmon_data *data)
> +{
> +	unsigned char buf[REQUEST_HWMON_CMD2_LEN] = {0};
> +	int ret;
> +
> +	/* Set Fan input Real Time alarm mode */
> +	mutex_lock(&data->hwmon_lock);

Pointless lock (this is init code)

> +	ret = nct6694_read_msg(data->nct6694, REQUEST_HWMON_MOD,
> +			       REQUEST_HWMON_CMD2_OFFSET,
> +			       REQUEST_HWMON_CMD2_LEN, 0,
> +			       REQUEST_HWMON_CMD2_LEN, buf);
> +	if (ret)
> +		goto err;
> +
> +	buf[HWMON_SMI_CTRL_IDX] = 0x02;
> +
> +	ret = nct6694_write_msg(data->nct6694, REQUEST_HWMON_MOD,
> +				REQUEST_HWMON_CMD2_OFFSET,
> +				REQUEST_HWMON_CMD2_LEN, buf);
> +	if (ret)
> +		goto err;
> +
> +err:
> +	mutex_unlock(&data->hwmon_lock);
> +	return ret;
> +}
> +
> +static int nct6694_hwmon_probe(struct platform_device *pdev)
> +{
> +	struct nct6694_hwmon_data *data;
> +	struct nct6694 *nct6694 = dev_get_drvdata(pdev->dev.parent);
> +	struct device *hwmon_dev;
> +	int ret;
> +
> +	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
> +	if (!data)
> +		return -ENOMEM;
> +
> +	data->nct6694 = nct6694;
> +	mutex_init(&data->hwmon_lock);
> +	platform_set_drvdata(pdev, data);
> +
> +	ret = nct6694_hwmon_init(data);
> +	if (ret)
> +		return -EIO;

Again, do not overwrite error codes.

> +
> +	/* Register hwmon device to HWMON framework */
> +	hwmon_dev = devm_hwmon_device_register_with_info(&pdev->dev,
> +							 "nct6694", data,
> +							 &nct6694_chip_info,
> +							 NULL);
> +	if (IS_ERR(hwmon_dev)) {
> +		dev_err(&pdev->dev, "%s: Failed to register hwmon device!\n",
> +			__func__);

Use dev_err_probe(), and the function name is pointless.

> +		return PTR_ERR(hwmon_dev);
> +	}
> +
> +	return 0;
> +}
> +
> +static struct platform_driver nct6694_hwmon_driver = {
> +	.driver = {
> +		.name	= DRVNAME,
> +	},
> +	.probe		= nct6694_hwmon_probe,
> +};
> +
> +static int __init nct6694_init(void)
> +{
> +	int err;
> +
> +	err = platform_driver_register(&nct6694_hwmon_driver);
> +	if (!err) {
> +		if (err)

Seriously ? Read this code again. It is never reached (and pointless).

> +			platform_driver_unregister(&nct6694_hwmon_driver);
> +	}
> +
> +	return err;
> +}
> +subsys_initcall(nct6694_init);
> +
> +static void __exit nct6694_exit(void)
> +{
> +	platform_driver_unregister(&nct6694_hwmon_driver);
> +}
> +module_exit(nct6694_exit);
> +
> +MODULE_DESCRIPTION("USB-HWMON driver for NCT6694");
> +MODULE_AUTHOR("Ming Yu <tmyu0@nuvoton.com>");
> +MODULE_LICENSE("GPL");
Ming Yu Oct. 25, 2024, 3:22 p.m. UTC | #3
Dear Guenter,

Thank you for your comments.

Guenter Roeck <linux@roeck-us.net> 於 2024年10月24日 週四 下午10:53寫道:
>
> On 10/24/24 02:20, Kalesh Anakkur Purayil wrote:
> > On Thu, Oct 24, 2024 at 2:33 PM Ming Yu <a0282524688@gmail.com> wrote:
> >>
> >> This driver supports Hardware monitor functionality for NCT6694 MFD
> >> device based on USB interface.
> >>
> >> Signed-off-by: Ming Yu <tmyu0@nuvoton.com>
> >> ---
> >>   MAINTAINERS                   |   1 +
> >>   drivers/hwmon/Kconfig         |  10 +
> >>   drivers/hwmon/Makefile        |   1 +
> >>   drivers/hwmon/nct6694-hwmon.c | 407 ++++++++++++++++++++++++++++++++++
> >>   4 files changed, 419 insertions(+)
> >>   create mode 100644 drivers/hwmon/nct6694-hwmon.c
> >>
> >> diff --git a/MAINTAINERS b/MAINTAINERS
> >> index 63387c0d4ab6..2aa87ad84156 100644
> >> --- a/MAINTAINERS
> >> +++ b/MAINTAINERS
> >> @@ -16439,6 +16439,7 @@ M:      Ming Yu <tmyu0@nuvoton.com>
> >>   L:     linux-kernel@vger.kernel.org
> >>   S:     Supported
> >>   F:     drivers/gpio/gpio-nct6694.c
> >> +F:     drivers/hwmon/nct6694-hwmon.c
> >>   F:     drivers/i2c/busses/i2c-nct6694.c
> >>   F:     drivers/mfd/nct6694.c
> >>   F:     drivers/net/can/nct6694_canfd.c
> >> diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
> >> index 08a3c863f80a..740e4afe6582 100644
> >> --- a/drivers/hwmon/Kconfig
> >> +++ b/drivers/hwmon/Kconfig
> >> @@ -1625,6 +1625,16 @@ config SENSORS_NCT6683
> >>            This driver can also be built as a module. If so, the module
> >>            will be called nct6683.
> >>
> >> +config SENSORS_NCT6694
> >> +       tristate "Nuvoton NCT6694 Hardware Monitor support"
> >> +       depends on MFD_NCT6694
> >> +       help
> >> +         Say Y here to support Nuvoton NCT6694 hardware monitoring
> >> +         functionality.
> >> +
> >> +         This driver can also be built as a module. If so, the module
> >> +         will be called nct6694-hwmon.
> >> +
> >>   config SENSORS_NCT6775_CORE
> >>          tristate
> >>          select REGMAP
> >> diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
> >> index 9554d2fdcf7b..729961176d00 100644
> >> --- a/drivers/hwmon/Makefile
> >> +++ b/drivers/hwmon/Makefile
> >> @@ -167,6 +167,7 @@ obj-$(CONFIG_SENSORS_MLXREG_FAN) += mlxreg-fan.o
> >>   obj-$(CONFIG_SENSORS_MENF21BMC_HWMON) += menf21bmc_hwmon.o
> >>   obj-$(CONFIG_SENSORS_MR75203)  += mr75203.o
> >>   obj-$(CONFIG_SENSORS_NCT6683)  += nct6683.o
> >> +obj-$(CONFIG_SENSORS_NCT6694)  += nct6694-hwmon.o
> >>   obj-$(CONFIG_SENSORS_NCT6775_CORE) += nct6775-core.o
> >>   nct6775-objs                   := nct6775-platform.o
> >>   obj-$(CONFIG_SENSORS_NCT6775)  += nct6775.o
> >> diff --git a/drivers/hwmon/nct6694-hwmon.c b/drivers/hwmon/nct6694-hwmon.c
> >> new file mode 100644
> >> index 000000000000..7d7d22a650b0
> >> --- /dev/null
> >> +++ b/drivers/hwmon/nct6694-hwmon.c
> >> @@ -0,0 +1,407 @@
> >> +// SPDX-License-Identifier: GPL-2.0
> >> +/*
> >> + * Nuvoton NCT6694 HWMON driver based on USB interface.
> >> + *
> >> + * Copyright (C) 2024 Nuvoton Technology Corp.
> >> + */
> >> +
> >> +#include <linux/slab.h>
> >> +#include <linux/kernel.h>
> >> +#include <linux/module.h>
> >> +#include <linux/hwmon.h>
> >> +#include <linux/platform_device.h>
> >> +#include <linux/mfd/nct6694.h>
> >> +
> >> +#define DRVNAME "nct6694-hwmon"
> >> +
> >> +/* Host interface */
> >> +#define REQUEST_RPT_MOD                        0xFF
> >> +#define REQUEST_HWMON_MOD              0x00
> >> +
> >> +/* Report Channel */
> >> +#define HWMON_FIN_IDX(x)               (0x50 + ((x) * 2))
> >> +#define HWMON_FIN_STS(x)               (0x6E + (x))
> >> +#define HWMON_PWM_IDX(x)               (0x70 + (x))
> >> +
> >> +/* Message Channel*/
> >> +/* Command 00h */
> >> +#define REQUEST_HWMON_CMD0_LEN         0x40
> >> +#define REQUEST_HWMON_CMD0_OFFSET      0x0000  /* OFFSET = SEL|CMD */
> >> +#define HWMON_FIN_EN(x)                        (0x04 + (x))
> >> +#define HWMON_PWM_FREQ_IDX(x)          (0x30 + (x))
> >> +/* Command 02h */
> >> +#define REQUEST_HWMON_CMD2_LEN         0x90
> >> +#define REQUEST_HWMON_CMD2_OFFSET      0x0002  /* OFFSET = SEL|CMD */
> >> +#define HWMON_SMI_CTRL_IDX             0x00
> >> +#define HWMON_FIN_LIMIT_IDX(x)         (0x70 + ((x) * 2))
> >> +#define HWMON_CMD2_HYST_MASK           0x1F
> >> +/* Command 03h */
> >> +#define REQUEST_HWMON_CMD3_LEN         0x08
> >> +#define REQUEST_HWMON_CMD3_OFFSET      0x0003  /* OFFSET = SEL|CMD */
> >> +
> >> +struct nct6694_hwmon_data {
> >> +       struct nct6694 *nct6694;
> >> +
> >> +       /* Make sure read & write commands are consecutive */
> >> +       struct mutex hwmon_lock;
> >> +};
> >> +
> >> +#define NCT6694_HWMON_FAN_CONFIG (HWMON_F_ENABLE | HWMON_F_INPUT | \
> >> +                                 HWMON_F_MIN | HWMON_F_MIN_ALARM)
> >> +#define NCT6694_HWMON_PWM_CONFIG (HWMON_PWM_INPUT | HWMON_PWM_FREQ)
> >> +
> >> +static const struct hwmon_channel_info *nct6694_info[] = {
> >> +       HWMON_CHANNEL_INFO(fan,
> >> +                          NCT6694_HWMON_FAN_CONFIG,    /* FIN0 */
> >> +                          NCT6694_HWMON_FAN_CONFIG,    /* FIN1 */
> >> +                          NCT6694_HWMON_FAN_CONFIG,    /* FIN2 */
> >> +                          NCT6694_HWMON_FAN_CONFIG,    /* FIN3 */
> >> +                          NCT6694_HWMON_FAN_CONFIG,    /* FIN4 */
> >> +                          NCT6694_HWMON_FAN_CONFIG,    /* FIN5 */
> >> +                          NCT6694_HWMON_FAN_CONFIG,    /* FIN6 */
> >> +                          NCT6694_HWMON_FAN_CONFIG,    /* FIN7 */
> >> +                          NCT6694_HWMON_FAN_CONFIG,    /* FIN8 */
> >> +                          NCT6694_HWMON_FAN_CONFIG),   /* FIN9 */
> >> +
> >> +       HWMON_CHANNEL_INFO(pwm,
> >> +                          NCT6694_HWMON_PWM_CONFIG,    /* PWM0 */
> >> +                          NCT6694_HWMON_PWM_CONFIG,    /* PWM1 */
> >> +                          NCT6694_HWMON_PWM_CONFIG,    /* PWM2 */
> >> +                          NCT6694_HWMON_PWM_CONFIG,    /* PWM3 */
> >> +                          NCT6694_HWMON_PWM_CONFIG,    /* PWM4 */
> >> +                          NCT6694_HWMON_PWM_CONFIG,    /* PWM5 */
> >> +                          NCT6694_HWMON_PWM_CONFIG,    /* PWM6 */
> >> +                          NCT6694_HWMON_PWM_CONFIG,    /* PWM7 */
> >> +                          NCT6694_HWMON_PWM_CONFIG,    /* PWM8 */
> >> +                          NCT6694_HWMON_PWM_CONFIG),   /* PWM9 */
> >> +       NULL
> >> +};
> >> +
> >> +static int nct6694_fan_read(struct device *dev, u32 attr, int channel,
> >> +                           long *val)
> >> +{
> >> +       struct nct6694_hwmon_data *data = dev_get_drvdata(dev);
> >> +       unsigned char buf[2];
> >> +       int ret;
> >> +
> >> +       switch (attr) {
> >> +       case hwmon_fan_enable:
> >> +               ret = nct6694_read_msg(data->nct6694, REQUEST_HWMON_MOD,
> >> +                                      REQUEST_HWMON_CMD0_OFFSET,
> >> +                                      REQUEST_HWMON_CMD0_LEN,
> >> +                                      HWMON_FIN_EN(channel / 8),
> >> +                                      1, buf);
> >> +               if (ret)
> >> +                       return -EINVAL;
> >> +
> >> +               *val = buf[0] & BIT(channel % 8) ? 1 : 0;
> >> +
> >> +               break;
> >> +
> >> +       case hwmon_fan_input:
> >> +               ret = nct6694_read_msg(data->nct6694, REQUEST_RPT_MOD,
> >> +                                      HWMON_FIN_IDX(channel), 2, 0,
> >> +                                      2, buf);
> >> +               if (ret)
> >> +                       return -EINVAL;
> >> +
> >> +               *val = (buf[1] | (buf[0] << 8)) & 0xFFFF;
> >> +
> >> +               break;
> >> +
> >> +       case hwmon_fan_min:
> >> +               ret = nct6694_read_msg(data->nct6694, REQUEST_HWMON_MOD,
> >> +                                      REQUEST_HWMON_CMD2_OFFSET,
> >> +                                      REQUEST_HWMON_CMD2_LEN,
> >> +                                      HWMON_FIN_LIMIT_IDX(channel),
> >> +                                      2, buf);
> >> +               if (ret)
> >> +                       return -EINVAL;
> >> +
> >> +               *val = (buf[1] | (buf[0] << 8)) & 0xFFFF;
> >> +
> >> +               break;
> >> +
> >> +       case hwmon_fan_min_alarm:
> >> +               ret = nct6694_read_msg(data->nct6694, REQUEST_RPT_MOD,
> >> +                                      HWMON_FIN_STS(channel / 8),
> >> +                                      1, 0, 1, buf);
> >> +               if (ret)
> >> +                       return -EINVAL;
> >> +
> >> +               *val = buf[0] & BIT(channel % 8);
> >> +
> >> +               break;
> >> +
> >> +       default:
> >> +               return -EOPNOTSUPP;
> >> +       }
> >> +
> >> +       return 0;
> >> +}
> >> +
> >> +static int nct6694_pwm_read(struct device *dev, u32 attr, int channel,
> >> +                           long *val)
> >> +{
> >> +       struct nct6694_hwmon_data *data = dev_get_drvdata(dev);
> >> +       unsigned char buf;
> >> +       int ret;
> >> +
> >> +       switch (attr) {
> >> +       case hwmon_pwm_input:
> >> +               ret = nct6694_read_msg(data->nct6694, REQUEST_RPT_MOD,
> >> +                                      HWMON_PWM_IDX(channel),
> >> +                                      1, 0, 1, &buf);
> >> +               if (ret)
> >> +                       return -EINVAL;
> >> +
> >> +               *val = buf;
> >> +
> >> +               break;
> >> +       case hwmon_pwm_freq:
> >> +               ret = nct6694_read_msg(data->nct6694, REQUEST_HWMON_MOD,
> >> +                                      REQUEST_HWMON_CMD0_OFFSET,
> >> +                                      REQUEST_HWMON_CMD0_LEN,
> >> +                                      HWMON_PWM_FREQ_IDX(channel),
> >> +                                      1, &buf);
> >> +               if (ret)
> >> +                       return -EINVAL;
> >> +
> >> +               *val = buf * 25000 / 255;
> >> +
> >> +               break;
> >> +
> >> +       default:
> >> +               return -EOPNOTSUPP;
> >> +       }
> >> +
> >> +       return 0;
> >> +}
> >> +
> >> +static int nct6694_fan_write(struct device *dev, u32 attr, int channel,
> >> +                            long val)
> >> +{
> >> +       struct nct6694_hwmon_data *data = dev_get_drvdata(dev);
> >> +       unsigned char enable_buf[REQUEST_HWMON_CMD0_LEN] = {0};
> > [Kalesh] Please try to maintain RCT order for variable declaration
>
> Ok, but that is already the case here ?

[Ming] Is there anything that needs to be changed?

>
> >> +       unsigned char buf[REQUEST_HWMON_CMD2_LEN] = {0};
> >> +       u16 fan_val = (u16)val;
> >> +       int ret;
> >> +
> >> +       switch (attr) {
> >> +       case hwmon_fan_enable:
> >> +               mutex_lock(&data->hwmon_lock);
> >> +               ret = nct6694_read_msg(data->nct6694, REQUEST_HWMON_MOD,
> >> +                                      REQUEST_HWMON_CMD0_OFFSET,
> >> +                                      REQUEST_HWMON_CMD0_LEN, 0,
> >> +                                      REQUEST_HWMON_CMD0_LEN,
> >> +                                      enable_buf);
> >> +               if (ret)
> >> +                       goto err;
> >> +
> >> +               if (val)
> >> +                       enable_buf[HWMON_FIN_EN(channel / 8)] |= BIT(channel % 8);
> >> +               else
> >> +                       enable_buf[HWMON_FIN_EN(channel / 8)] &= ~BIT(channel % 8);
> >> +
> >> +               ret = nct6694_write_msg(data->nct6694, REQUEST_HWMON_MOD,
> >> +                                       REQUEST_HWMON_CMD0_OFFSET,
> >> +                                       REQUEST_HWMON_CMD0_LEN, enable_buf);
> >> +               if (ret)
> >> +                       goto err;
> >> +
> >> +               break;
> >> +
> >> +       case hwmon_fan_min:
> >> +               mutex_lock(&data->hwmon_lock);
> >> +               ret = nct6694_read_msg(data->nct6694, REQUEST_HWMON_MOD,
> >> +                                      REQUEST_HWMON_CMD2_OFFSET,
> >> +                                      REQUEST_HWMON_CMD2_LEN, 0,
> >> +                                      REQUEST_HWMON_CMD2_LEN, buf);
> >> +               if (ret)
> >> +                       goto err;
> >> +
> >> +               buf[HWMON_FIN_LIMIT_IDX(channel)] = (u8)((fan_val >> 8) & 0xFF);
> >> +               buf[HWMON_FIN_LIMIT_IDX(channel) + 1] = (u8)(fan_val & 0xFF);
> >> +               ret = nct6694_write_msg(data->nct6694, REQUEST_HWMON_MOD,
> >> +                                       REQUEST_HWMON_CMD2_OFFSET,
> >> +                                       REQUEST_HWMON_CMD2_LEN, buf);
> >> +               if (ret)
> >> +                       goto err;
> >> +
> >> +               break;
> >> +
> >> +       default:
> >> +               ret = -EOPNOTSUPP;
> > [Kalesh] If you initialize "ret = -EOPNOTSUPP;" during declararion,
> > you can just break from here.
>
> You are missing the point. The lock wasn't acquired here in the first place.
> It is conceptually wrong to acquire a lock in the switch statement and release
> it outside. This patch is a case in point.

[Ming] Okay! I'll acquire the lock before switch() in the next patch.

>
> >> +               goto err;
> >> +       }
> >> +
> >> +err:
> >> +       mutex_unlock(&data->hwmon_lock);
> >> +       return ret;
> >> +}
> >> +
> >> +static int nct6694_read(struct device *dev, enum hwmon_sensor_types type,
> >> +                       u32 attr, int channel, long *val)
> >> +{
> >> +       switch (type) {
> >> +       case hwmon_fan: /* in RPM */
> >> +               return nct6694_fan_read(dev, attr, channel, val);
> >> +
> >> +       case hwmon_pwm: /* in value 0~255 */
> >> +               return nct6694_pwm_read(dev, attr, channel, val);
> >> +
> >> +       default:
> >> +               return -EOPNOTSUPP;
> >> +       }
> >> +
> >> +       return 0;
> >> +}
> >> +
> >> +static int nct6694_write(struct device *dev, enum hwmon_sensor_types type,
> >> +                        u32 attr, int channel, long val)
> >> +{
> >> +       switch (type) {
> >> +       case hwmon_fan:
> >> +               return nct6694_fan_write(dev, attr, channel, val);
> >> +       default:
> >> +               return -EOPNOTSUPP;
> >> +       }
> > [Kalesh] You can use simple if condition here than a switch like:
> > if (type != hwmon_fan)
> >           return -EOPNOTSUPP;
> > return nct6694_fan_write(dev, attr, channel, val);
>
> That is a bit POV. I'd leave that to the developer.
> More important is that the return statements after the switch are unnecessary
> and never reached if each case returns immediately.

[Ming] Okay! I'll drop it in the next patch.

>
> >> +
> >> +       return 0;
> >> +}
> >> +
> >> +static umode_t nct6694_is_visible(const void *data, enum hwmon_sensor_types type,
> >> +                                 u32 attr, int channel)
> >> +{
> >> +       switch (type) {
> >> +       case hwmon_fan:
> >> +               switch (attr) {
> >> +               case hwmon_fan_enable:
> >> +               case hwmon_fan_min:
> >> +                       return 0644;
> > [Kalesh] I think there is no need to leave a new line in between cases
> >> +
> >> +               case hwmon_fan_input:
> >> +               case hwmon_fan_min_alarm:
> >> +                       return 0444;
> >> +
> >> +               default:
> >> +                       return 0;
> >> +               }
> >> +
> >> +       case hwmon_pwm:
> >> +               switch (attr) {
> >> +               case hwmon_pwm_input:
> >> +               case hwmon_pwm_freq:
> >> +                       return 0444;
> >> +               default:
> >> +                       return 0;
> >> +               }
> >> +
> >> +       default:
> >> +               return 0;
> >> +       }
> >> +
> >> +       return 0;
> > [Kalesh] This return statement looks redundant as the execution never
> > reaches here. Same comment applies to other functions above as well.
> >> +}
> >> +
> >> +static const struct hwmon_ops nct6694_hwmon_ops = {
> >> +       .is_visible = nct6694_is_visible,
> >> +       .read = nct6694_read,
> >> +       .write = nct6694_write,
> >> +};
> >> +
> >> +static const struct hwmon_chip_info nct6694_chip_info = {
> >> +       .ops = &nct6694_hwmon_ops,
> >> +       .info = nct6694_info,
> >> +};
> >> +
> >> +static int nct6694_hwmon_init(struct nct6694_hwmon_data *data)
> >> +{
> >> +       unsigned char buf[REQUEST_HWMON_CMD2_LEN] = {0};
> >> +       int ret;
> >> +
> >> +       /* Set Fan input Real Time alarm mode */
> >> +       mutex_lock(&data->hwmon_lock);
> >> +       ret = nct6694_read_msg(data->nct6694, REQUEST_HWMON_MOD,
> >> +                              REQUEST_HWMON_CMD2_OFFSET,
> >> +                              REQUEST_HWMON_CMD2_LEN, 0,
> >> +                              REQUEST_HWMON_CMD2_LEN, buf);
> >> +       if (ret)
> >> +               goto err;
> > [Kalesh] It would be better to rename the label as "unlock". Same
> > comment on other functions as well.
>
> The lock is not needed here in the first place. The function is called
> exactly once during initialization.

[Ming] I'll remove the lock in the next patch!

>
> >> +
> >> +       buf[HWMON_SMI_CTRL_IDX] = 0x02;
> >> +
> >> +       ret = nct6694_write_msg(data->nct6694, REQUEST_HWMON_MOD,
> >> +                               REQUEST_HWMON_CMD2_OFFSET,
> >> +                               REQUEST_HWMON_CMD2_LEN, buf);
> >> +       if (ret)
> >> +               goto err;
> >> +
> >> +err:
> >> +       mutex_unlock(&data->hwmon_lock);
> >> +       return ret;
> >> +}
> >> +
> >> +static int nct6694_hwmon_probe(struct platform_device *pdev)
> >> +{
> >> +       struct nct6694_hwmon_data *data;
> >> +       struct nct6694 *nct6694 = dev_get_drvdata(pdev->dev.parent);
> >> +       struct device *hwmon_dev;
> >> +       int ret;
> >> +
> >> +       data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
> >> +       if (!data)
> >> +               return -ENOMEM;
> >> +
> >> +       data->nct6694 = nct6694;
> >> +       mutex_init(&data->hwmon_lock);
> >> +       platform_set_drvdata(pdev, data);
> >> +
> >> +       ret = nct6694_hwmon_init(data);
> >> +       if (ret)
> >> +               return -EIO;
> >> +
> >> +       /* Register hwmon device to HWMON framework */
> >> +       hwmon_dev = devm_hwmon_device_register_with_info(&pdev->dev,
> >> +                                                        "nct6694", data,
> >> +                                                        &nct6694_chip_info,
> >> +                                                        NULL);
> >> +       if (IS_ERR(hwmon_dev)) {
> >> +               dev_err(&pdev->dev, "%s: Failed to register hwmon device!\n",
> >> +                       __func__);
> >> +               return PTR_ERR(hwmon_dev);
> >> +       }
> >> +
> >> +       return 0;
> >> +}
> >> +
> >> +static struct platform_driver nct6694_hwmon_driver = {
> >> +       .driver = {
> >> +               .name   = DRVNAME,
> >> +       },
> >> +       .probe          = nct6694_hwmon_probe,
> >> +};
> >> +
> >> +static int __init nct6694_init(void)
> >> +{
> >> +       int err;
> >> +
> >> +       err = platform_driver_register(&nct6694_hwmon_driver);
> >> +       if (!err) {
> >> +               if (err)
> > [Kalesh] This whole check looks strange. You can simplify this function as:
> > return platform_driver_register(&nct6694_hwmon_driver);
> >> +                       platform_driver_unregister(&nct6694_hwmon_driver);
> >> +       }
> >> +
> >> +       return err;
> >> +}
> >> +subsys_initcall(nct6694_init);
> >> +
> >> +static void __exit nct6694_exit(void)
> >> +{
> >> +       platform_driver_unregister(&nct6694_hwmon_driver);
> >> +}
> >> +module_exit(nct6694_exit);
> >> +
> >> +MODULE_DESCRIPTION("USB-HWMON driver for NCT6694");
> >> +MODULE_AUTHOR("Ming Yu <tmyu0@nuvoton.com>");
> >> +MODULE_LICENSE("GPL");
> >> --
> >> 2.34.1
> >>
> >>
> >
> >
>

[Ming] For platform driver registration, I'll change it to
module_platform_driver() in the next patch.

Thank,
Ming
Ming Yu Oct. 25, 2024, 3:33 p.m. UTC | #4
Hi Guenter,

I will remove the unnecessary return statement and lock, and update
the part of the code you mentioned.

Thanks,
Ming

Guenter Roeck <linux@roeck-us.net> 於 2024年10月24日 週四 下午11:03寫道:
>
> On 10/24/24 01:59, Ming Yu wrote:
> > This driver supports Hardware monitor functionality for NCT6694 MFD
> > device based on USB interface.
> >
> > Signed-off-by: Ming Yu <tmyu0@nuvoton.com>
> > ---
> >   MAINTAINERS                   |   1 +
> >   drivers/hwmon/Kconfig         |  10 +
> >   drivers/hwmon/Makefile        |   1 +
> >   drivers/hwmon/nct6694-hwmon.c | 407 ++++++++++++++++++++++++++++++++++
> >   4 files changed, 419 insertions(+)
> >   create mode 100644 drivers/hwmon/nct6694-hwmon.c
> >
> > diff --git a/MAINTAINERS b/MAINTAINERS
> > index 63387c0d4ab6..2aa87ad84156 100644
> > --- a/MAINTAINERS
> > +++ b/MAINTAINERS
> > @@ -16439,6 +16439,7 @@ M:    Ming Yu <tmyu0@nuvoton.com>
> >   L:  linux-kernel@vger.kernel.org
> >   S:  Supported
> >   F:  drivers/gpio/gpio-nct6694.c
> > +F:   drivers/hwmon/nct6694-hwmon.c
> >   F:  drivers/i2c/busses/i2c-nct6694.c
> >   F:  drivers/mfd/nct6694.c
> >   F:  drivers/net/can/nct6694_canfd.c
> > diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
> > index 08a3c863f80a..740e4afe6582 100644
> > --- a/drivers/hwmon/Kconfig
> > +++ b/drivers/hwmon/Kconfig
> > @@ -1625,6 +1625,16 @@ config SENSORS_NCT6683
> >         This driver can also be built as a module. If so, the module
> >         will be called nct6683.
> >
> > +config SENSORS_NCT6694
> > +     tristate "Nuvoton NCT6694 Hardware Monitor support"
> > +     depends on MFD_NCT6694
> > +     help
> > +       Say Y here to support Nuvoton NCT6694 hardware monitoring
> > +       functionality.
> > +
> > +       This driver can also be built as a module. If so, the module
> > +       will be called nct6694-hwmon.
> > +
> >   config SENSORS_NCT6775_CORE
> >       tristate
> >       select REGMAP
> > diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
> > index 9554d2fdcf7b..729961176d00 100644
> > --- a/drivers/hwmon/Makefile
> > +++ b/drivers/hwmon/Makefile
> > @@ -167,6 +167,7 @@ obj-$(CONFIG_SENSORS_MLXREG_FAN) += mlxreg-fan.o
> >   obj-$(CONFIG_SENSORS_MENF21BMC_HWMON) += menf21bmc_hwmon.o
> >   obj-$(CONFIG_SENSORS_MR75203)       += mr75203.o
> >   obj-$(CONFIG_SENSORS_NCT6683)       += nct6683.o
> > +obj-$(CONFIG_SENSORS_NCT6694)        += nct6694-hwmon.o
> >   obj-$(CONFIG_SENSORS_NCT6775_CORE) += nct6775-core.o
> >   nct6775-objs                        := nct6775-platform.o
> >   obj-$(CONFIG_SENSORS_NCT6775)       += nct6775.o
> > diff --git a/drivers/hwmon/nct6694-hwmon.c b/drivers/hwmon/nct6694-hwmon.c
> > new file mode 100644
> > index 000000000000..7d7d22a650b0
> > --- /dev/null
> > +++ b/drivers/hwmon/nct6694-hwmon.c
> > @@ -0,0 +1,407 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * Nuvoton NCT6694 HWMON driver based on USB interface.
> > + *
> > + * Copyright (C) 2024 Nuvoton Technology Corp.
> > + */
> > +
> > +#include <linux/slab.h>
> > +#include <linux/kernel.h>
> > +#include <linux/module.h>
> > +#include <linux/hwmon.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/mfd/nct6694.h>
> > +
> > +#define DRVNAME "nct6694-hwmon"
> > +
> > +/* Host interface */
> > +#define REQUEST_RPT_MOD                      0xFF
> > +#define REQUEST_HWMON_MOD            0x00
> > +
> > +/* Report Channel */
> > +#define HWMON_FIN_IDX(x)             (0x50 + ((x) * 2))
> > +#define HWMON_FIN_STS(x)             (0x6E + (x))
> > +#define HWMON_PWM_IDX(x)             (0x70 + (x))
> > +
> > +/* Message Channel*/
> > +/* Command 00h */
> > +#define REQUEST_HWMON_CMD0_LEN               0x40
> > +#define REQUEST_HWMON_CMD0_OFFSET    0x0000  /* OFFSET = SEL|CMD */
> > +#define HWMON_FIN_EN(x)                      (0x04 + (x))
> > +#define HWMON_PWM_FREQ_IDX(x)                (0x30 + (x))
> > +/* Command 02h */
> > +#define REQUEST_HWMON_CMD2_LEN               0x90
> > +#define REQUEST_HWMON_CMD2_OFFSET    0x0002  /* OFFSET = SEL|CMD */
> > +#define HWMON_SMI_CTRL_IDX           0x00
> > +#define HWMON_FIN_LIMIT_IDX(x)               (0x70 + ((x) * 2))
> > +#define HWMON_CMD2_HYST_MASK         0x1F
> > +/* Command 03h */
> > +#define REQUEST_HWMON_CMD3_LEN               0x08
> > +#define REQUEST_HWMON_CMD3_OFFSET    0x0003  /* OFFSET = SEL|CMD */
> > +
> > +struct nct6694_hwmon_data {
> > +     struct nct6694 *nct6694;
> > +
> > +     /* Make sure read & write commands are consecutive */
> > +     struct mutex hwmon_lock;
> > +};
> > +
> > +#define NCT6694_HWMON_FAN_CONFIG (HWMON_F_ENABLE | HWMON_F_INPUT | \
> > +                               HWMON_F_MIN | HWMON_F_MIN_ALARM)
> > +#define NCT6694_HWMON_PWM_CONFIG (HWMON_PWM_INPUT | HWMON_PWM_FREQ)
> > +
> > +static const struct hwmon_channel_info *nct6694_info[] = {
> > +     HWMON_CHANNEL_INFO(fan,
> > +                        NCT6694_HWMON_FAN_CONFIG,    /* FIN0 */
> > +                        NCT6694_HWMON_FAN_CONFIG,    /* FIN1 */
> > +                        NCT6694_HWMON_FAN_CONFIG,    /* FIN2 */
> > +                        NCT6694_HWMON_FAN_CONFIG,    /* FIN3 */
> > +                        NCT6694_HWMON_FAN_CONFIG,    /* FIN4 */
> > +                        NCT6694_HWMON_FAN_CONFIG,    /* FIN5 */
> > +                        NCT6694_HWMON_FAN_CONFIG,    /* FIN6 */
> > +                        NCT6694_HWMON_FAN_CONFIG,    /* FIN7 */
> > +                        NCT6694_HWMON_FAN_CONFIG,    /* FIN8 */
> > +                        NCT6694_HWMON_FAN_CONFIG),   /* FIN9 */
> > +
> > +     HWMON_CHANNEL_INFO(pwm,
> > +                        NCT6694_HWMON_PWM_CONFIG,    /* PWM0 */
> > +                        NCT6694_HWMON_PWM_CONFIG,    /* PWM1 */
> > +                        NCT6694_HWMON_PWM_CONFIG,    /* PWM2 */
> > +                        NCT6694_HWMON_PWM_CONFIG,    /* PWM3 */
> > +                        NCT6694_HWMON_PWM_CONFIG,    /* PWM4 */
> > +                        NCT6694_HWMON_PWM_CONFIG,    /* PWM5 */
> > +                        NCT6694_HWMON_PWM_CONFIG,    /* PWM6 */
> > +                        NCT6694_HWMON_PWM_CONFIG,    /* PWM7 */
> > +                        NCT6694_HWMON_PWM_CONFIG,    /* PWM8 */
> > +                        NCT6694_HWMON_PWM_CONFIG),   /* PWM9 */
> > +     NULL
> > +};
> > +
> > +static int nct6694_fan_read(struct device *dev, u32 attr, int channel,
> > +                         long *val)
> > +{
> > +     struct nct6694_hwmon_data *data = dev_get_drvdata(dev);
> > +     unsigned char buf[2];
> > +     int ret;
> > +
> > +     switch (attr) {
> > +     case hwmon_fan_enable:
> > +             ret = nct6694_read_msg(data->nct6694, REQUEST_HWMON_MOD,
> > +                                    REQUEST_HWMON_CMD0_OFFSET,
> > +                                    REQUEST_HWMON_CMD0_LEN,
> > +                                    HWMON_FIN_EN(channel / 8),
> > +                                    1, buf);
> > +             if (ret)
> > +                     return -EINVAL;
>
> Do not overwrite error return values.
>
> > +
> > +             *val = buf[0] & BIT(channel % 8) ? 1 : 0;
> > +
> > +             break;
> > +
> > +     case hwmon_fan_input:
> > +             ret = nct6694_read_msg(data->nct6694, REQUEST_RPT_MOD,
> > +                                    HWMON_FIN_IDX(channel), 2, 0,
> > +                                    2, buf);
> > +             if (ret)
> > +                     return -EINVAL;
> > +
> > +             *val = (buf[1] | (buf[0] << 8)) & 0xFFFF;
> > +
> > +             break;
> > +
> > +     case hwmon_fan_min:
> > +             ret = nct6694_read_msg(data->nct6694, REQUEST_HWMON_MOD,
> > +                                    REQUEST_HWMON_CMD2_OFFSET,
> > +                                    REQUEST_HWMON_CMD2_LEN,
> > +                                    HWMON_FIN_LIMIT_IDX(channel),
> > +                                    2, buf);
> > +             if (ret)
> > +                     return -EINVAL;
> > +
> > +             *val = (buf[1] | (buf[0] << 8)) & 0xFFFF;
> > +
> > +             break;
> > +
> > +     case hwmon_fan_min_alarm:
> > +             ret = nct6694_read_msg(data->nct6694, REQUEST_RPT_MOD,
> > +                                    HWMON_FIN_STS(channel / 8),
> > +                                    1, 0, 1, buf);
> > +             if (ret)
> > +                     return -EINVAL;
> > +
> > +             *val = buf[0] & BIT(channel % 8);
> > +
> > +             break;
> > +
> > +     default:
> > +             return -EOPNOTSUPP;
> > +     }
> > +
> > +     return 0;
> > +}
> > +
> > +static int nct6694_pwm_read(struct device *dev, u32 attr, int channel,
> > +                         long *val)
> > +{
> > +     struct nct6694_hwmon_data *data = dev_get_drvdata(dev);
> > +     unsigned char buf;
> > +     int ret;
> > +
> > +     switch (attr) {
> > +     case hwmon_pwm_input:
> > +             ret = nct6694_read_msg(data->nct6694, REQUEST_RPT_MOD,
> > +                                    HWMON_PWM_IDX(channel),
> > +                                    1, 0, 1, &buf);
> > +             if (ret)
> > +                     return -EINVAL;
> > +
> > +             *val = buf;
> > +
> > +             break;
> > +     case hwmon_pwm_freq:
> > +             ret = nct6694_read_msg(data->nct6694, REQUEST_HWMON_MOD,
> > +                                    REQUEST_HWMON_CMD0_OFFSET,
> > +                                    REQUEST_HWMON_CMD0_LEN,
> > +                                    HWMON_PWM_FREQ_IDX(channel),
> > +                                    1, &buf);
> > +             if (ret)
> > +                     return -EINVAL;
> > +
> > +             *val = buf * 25000 / 255;
> > +
> > +             break;
> > +
> > +     default:
> > +             return -EOPNOTSUPP;
> > +     }
> > +
> > +     return 0;
> > +}
> > +
> > +static int nct6694_fan_write(struct device *dev, u32 attr, int channel,
> > +                          long val)
> > +{
> > +     struct nct6694_hwmon_data *data = dev_get_drvdata(dev);
> > +     unsigned char enable_buf[REQUEST_HWMON_CMD0_LEN] = {0};
> > +     unsigned char buf[REQUEST_HWMON_CMD2_LEN] = {0};
> > +     u16 fan_val = (u16)val;
>
> This is wrong. It will result in overflows/underflows if out of range
> values are provided, and the driver should not write 0 if the user
> writes 65536. You need to use clamp_val() instead. For values with
> well defined range (specifically hwmon_fan_enable) you need to validate
> the parameter, not just take it as boolean.

[Ming] Okay! I'll update the code in the next patch.

>
> > +     int ret;
> > +
> > +     switch (attr) {
> > +     case hwmon_fan_enable:
> > +             mutex_lock(&data->hwmon_lock);
> > +             ret = nct6694_read_msg(data->nct6694, REQUEST_HWMON_MOD,
> > +                                    REQUEST_HWMON_CMD0_OFFSET,
> > +                                    REQUEST_HWMON_CMD0_LEN, 0,
> > +                                    REQUEST_HWMON_CMD0_LEN,
> > +                                    enable_buf);
> > +             if (ret)
> > +                     goto err;
> > +
> > +             if (val)
> > +                     enable_buf[HWMON_FIN_EN(channel / 8)] |= BIT(channel % 8);
> > +             else
> > +                     enable_buf[HWMON_FIN_EN(channel / 8)] &= ~BIT(channel % 8);
> > +
> > +             ret = nct6694_write_msg(data->nct6694, REQUEST_HWMON_MOD,
> > +                                     REQUEST_HWMON_CMD0_OFFSET,
> > +                                     REQUEST_HWMON_CMD0_LEN, enable_buf);
> > +             if (ret)
> > +                     goto err;
> > +
> > +             break;
> > +
> > +     case hwmon_fan_min:
> > +             mutex_lock(&data->hwmon_lock);
> > +             ret = nct6694_read_msg(data->nct6694, REQUEST_HWMON_MOD,
> > +                                    REQUEST_HWMON_CMD2_OFFSET,
> > +                                    REQUEST_HWMON_CMD2_LEN, 0,
> > +                                    REQUEST_HWMON_CMD2_LEN, buf);
> > +             if (ret)
> > +                     goto err;
> > +
> > +             buf[HWMON_FIN_LIMIT_IDX(channel)] = (u8)((fan_val >> 8) & 0xFF);
> > +             buf[HWMON_FIN_LIMIT_IDX(channel) + 1] = (u8)(fan_val & 0xFF);
> > +             ret = nct6694_write_msg(data->nct6694, REQUEST_HWMON_MOD,
> > +                                     REQUEST_HWMON_CMD2_OFFSET,
> > +                                     REQUEST_HWMON_CMD2_LEN, buf);
> > +             if (ret)
> > +                     goto err;
> > +
> > +             break;
>
> The error handler goto and the break accomplish exactly the same,
> thus the conditional goto is pointless.
>
> > +
> > +     default:
> > +             ret = -EOPNOTSUPP;
> > +             goto err;
>
> As mentioned in my other reply, the lock is not acquired here,
> causing an unbalanced unlock.
>
> > +     }
> > +
> > +err:
> > +     mutex_unlock(&data->hwmon_lock);
> > +     return ret;
> > +}
> > +
> > +static int nct6694_read(struct device *dev, enum hwmon_sensor_types type,
> > +                     u32 attr, int channel, long *val)
> > +{
> > +     switch (type) {
> > +     case hwmon_fan: /* in RPM */
> > +             return nct6694_fan_read(dev, attr, channel, val);
> > +
> > +     case hwmon_pwm: /* in value 0~255 */
> > +             return nct6694_pwm_read(dev, attr, channel, val);
> > +
> > +     default:
> > +             return -EOPNOTSUPP;
> > +     }
> > +
> > +     return 0;
>
> Unnecessary return statement. Also seen elsewhere.
>
> > +}
> > +
> > +static int nct6694_write(struct device *dev, enum hwmon_sensor_types type,
> > +                      u32 attr, int channel, long val)
> > +{
> > +     switch (type) {
> > +     case hwmon_fan:
> > +             return nct6694_fan_write(dev, attr, channel, val);
> > +     default:
> > +             return -EOPNOTSUPP;
> > +     }
> > +
> > +     return 0;
> > +}
> > +
> > +static umode_t nct6694_is_visible(const void *data, enum hwmon_sensor_types type,
> > +                               u32 attr, int channel)
> > +{
> > +     switch (type) {
> > +     case hwmon_fan:
> > +             switch (attr) {
> > +             case hwmon_fan_enable:
> > +             case hwmon_fan_min:
> > +                     return 0644;
> > +
> > +             case hwmon_fan_input:
> > +             case hwmon_fan_min_alarm:
> > +                     return 0444;
> > +
> > +             default:
> > +                     return 0;
> > +             }
> > +
> > +     case hwmon_pwm:
> > +             switch (attr) {
> > +             case hwmon_pwm_input:
> > +             case hwmon_pwm_freq:
> > +                     return 0444;
> > +             default:
> > +                     return 0;
> > +             }
> > +
> > +     default:
> > +             return 0;
> > +     }
> > +
> > +     return 0;
> > +}
> > +
> > +static const struct hwmon_ops nct6694_hwmon_ops = {
> > +     .is_visible = nct6694_is_visible,
> > +     .read = nct6694_read,
> > +     .write = nct6694_write,
> > +};
> > +
> > +static const struct hwmon_chip_info nct6694_chip_info = {
> > +     .ops = &nct6694_hwmon_ops,
> > +     .info = nct6694_info,
> > +};
> > +
> > +static int nct6694_hwmon_init(struct nct6694_hwmon_data *data)
> > +{
> > +     unsigned char buf[REQUEST_HWMON_CMD2_LEN] = {0};
> > +     int ret;
> > +
> > +     /* Set Fan input Real Time alarm mode */
> > +     mutex_lock(&data->hwmon_lock);
>
> Pointless lock (this is init code)
>
> > +     ret = nct6694_read_msg(data->nct6694, REQUEST_HWMON_MOD,
> > +                            REQUEST_HWMON_CMD2_OFFSET,
> > +                            REQUEST_HWMON_CMD2_LEN, 0,
> > +                            REQUEST_HWMON_CMD2_LEN, buf);
> > +     if (ret)
> > +             goto err;
> > +
> > +     buf[HWMON_SMI_CTRL_IDX] = 0x02;
> > +
> > +     ret = nct6694_write_msg(data->nct6694, REQUEST_HWMON_MOD,
> > +                             REQUEST_HWMON_CMD2_OFFSET,
> > +                             REQUEST_HWMON_CMD2_LEN, buf);
> > +     if (ret)
> > +             goto err;
> > +
> > +err:
> > +     mutex_unlock(&data->hwmon_lock);
> > +     return ret;
> > +}
> > +
> > +static int nct6694_hwmon_probe(struct platform_device *pdev)
> > +{
> > +     struct nct6694_hwmon_data *data;
> > +     struct nct6694 *nct6694 = dev_get_drvdata(pdev->dev.parent);
> > +     struct device *hwmon_dev;
> > +     int ret;
> > +
> > +     data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
> > +     if (!data)
> > +             return -ENOMEM;
> > +
> > +     data->nct6694 = nct6694;
> > +     mutex_init(&data->hwmon_lock);
> > +     platform_set_drvdata(pdev, data);
> > +
> > +     ret = nct6694_hwmon_init(data);
> > +     if (ret)
> > +             return -EIO;
>
> Again, do not overwrite error codes.
>
> > +
> > +     /* Register hwmon device to HWMON framework */
> > +     hwmon_dev = devm_hwmon_device_register_with_info(&pdev->dev,
> > +                                                      "nct6694", data,
> > +                                                      &nct6694_chip_info,
> > +                                                      NULL);
> > +     if (IS_ERR(hwmon_dev)) {
> > +             dev_err(&pdev->dev, "%s: Failed to register hwmon device!\n",
> > +                     __func__);
>
> Use dev_err_probe(), and the function name is pointless.

[Ming] Okay! I'll change it in the next patch.

>
> > +             return PTR_ERR(hwmon_dev);
> > +     }
> > +
> > +     return 0;
> > +}
> > +
> > +static struct platform_driver nct6694_hwmon_driver = {
> > +     .driver = {
> > +             .name   = DRVNAME,
> > +     },
> > +     .probe          = nct6694_hwmon_probe,
> > +};
> > +
> > +static int __init nct6694_init(void)
> > +{
> > +     int err;
> > +
> > +     err = platform_driver_register(&nct6694_hwmon_driver);
> > +     if (!err) {
> > +             if (err)
>
> Seriously ? Read this code again. It is never reached (and pointless).

[Ming] For platform driver registration, I'll change it to
module_platform_driver() in the next patch.

>
> > +                     platform_driver_unregister(&nct6694_hwmon_driver);
> > +     }
> > +
> > +     return err;
> > +}
> > +subsys_initcall(nct6694_init);
> > +
> > +static void __exit nct6694_exit(void)
> > +{
> > +     platform_driver_unregister(&nct6694_hwmon_driver);
> > +}
> > +module_exit(nct6694_exit);
> > +
> > +MODULE_DESCRIPTION("USB-HWMON driver for NCT6694");
> > +MODULE_AUTHOR("Ming Yu <tmyu0@nuvoton.com>");
> > +MODULE_LICENSE("GPL");
>
diff mbox series

Patch

diff --git a/MAINTAINERS b/MAINTAINERS
index 63387c0d4ab6..2aa87ad84156 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -16439,6 +16439,7 @@  M:	Ming Yu <tmyu0@nuvoton.com>
 L:	linux-kernel@vger.kernel.org
 S:	Supported
 F:	drivers/gpio/gpio-nct6694.c
+F:	drivers/hwmon/nct6694-hwmon.c
 F:	drivers/i2c/busses/i2c-nct6694.c
 F:	drivers/mfd/nct6694.c
 F:	drivers/net/can/nct6694_canfd.c
diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index 08a3c863f80a..740e4afe6582 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -1625,6 +1625,16 @@  config SENSORS_NCT6683
 	  This driver can also be built as a module. If so, the module
 	  will be called nct6683.
 
+config SENSORS_NCT6694
+	tristate "Nuvoton NCT6694 Hardware Monitor support"
+	depends on MFD_NCT6694
+	help
+	  Say Y here to support Nuvoton NCT6694 hardware monitoring
+	  functionality.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called nct6694-hwmon.
+
 config SENSORS_NCT6775_CORE
 	tristate
 	select REGMAP
diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
index 9554d2fdcf7b..729961176d00 100644
--- a/drivers/hwmon/Makefile
+++ b/drivers/hwmon/Makefile
@@ -167,6 +167,7 @@  obj-$(CONFIG_SENSORS_MLXREG_FAN) += mlxreg-fan.o
 obj-$(CONFIG_SENSORS_MENF21BMC_HWMON) += menf21bmc_hwmon.o
 obj-$(CONFIG_SENSORS_MR75203)	+= mr75203.o
 obj-$(CONFIG_SENSORS_NCT6683)	+= nct6683.o
+obj-$(CONFIG_SENSORS_NCT6694)	+= nct6694-hwmon.o
 obj-$(CONFIG_SENSORS_NCT6775_CORE) += nct6775-core.o
 nct6775-objs			:= nct6775-platform.o
 obj-$(CONFIG_SENSORS_NCT6775)	+= nct6775.o
diff --git a/drivers/hwmon/nct6694-hwmon.c b/drivers/hwmon/nct6694-hwmon.c
new file mode 100644
index 000000000000..7d7d22a650b0
--- /dev/null
+++ b/drivers/hwmon/nct6694-hwmon.c
@@ -0,0 +1,407 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Nuvoton NCT6694 HWMON driver based on USB interface.
+ *
+ * Copyright (C) 2024 Nuvoton Technology Corp.
+ */
+
+#include <linux/slab.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/hwmon.h>
+#include <linux/platform_device.h>
+#include <linux/mfd/nct6694.h>
+
+#define DRVNAME "nct6694-hwmon"
+
+/* Host interface */
+#define REQUEST_RPT_MOD			0xFF
+#define REQUEST_HWMON_MOD		0x00
+
+/* Report Channel */
+#define HWMON_FIN_IDX(x)		(0x50 + ((x) * 2))
+#define HWMON_FIN_STS(x)		(0x6E + (x))
+#define HWMON_PWM_IDX(x)		(0x70 + (x))
+
+/* Message Channel*/
+/* Command 00h */
+#define REQUEST_HWMON_CMD0_LEN		0x40
+#define REQUEST_HWMON_CMD0_OFFSET	0x0000	/* OFFSET = SEL|CMD */
+#define HWMON_FIN_EN(x)			(0x04 + (x))
+#define HWMON_PWM_FREQ_IDX(x)		(0x30 + (x))
+/* Command 02h */
+#define REQUEST_HWMON_CMD2_LEN		0x90
+#define REQUEST_HWMON_CMD2_OFFSET	0x0002	/* OFFSET = SEL|CMD */
+#define HWMON_SMI_CTRL_IDX		0x00
+#define HWMON_FIN_LIMIT_IDX(x)		(0x70 + ((x) * 2))
+#define HWMON_CMD2_HYST_MASK		0x1F
+/* Command 03h */
+#define REQUEST_HWMON_CMD3_LEN		0x08
+#define REQUEST_HWMON_CMD3_OFFSET	0x0003	/* OFFSET = SEL|CMD */
+
+struct nct6694_hwmon_data {
+	struct nct6694 *nct6694;
+
+	/* Make sure read & write commands are consecutive */
+	struct mutex hwmon_lock;
+};
+
+#define NCT6694_HWMON_FAN_CONFIG (HWMON_F_ENABLE | HWMON_F_INPUT | \
+				  HWMON_F_MIN | HWMON_F_MIN_ALARM)
+#define NCT6694_HWMON_PWM_CONFIG (HWMON_PWM_INPUT | HWMON_PWM_FREQ)
+
+static const struct hwmon_channel_info *nct6694_info[] = {
+	HWMON_CHANNEL_INFO(fan,
+			   NCT6694_HWMON_FAN_CONFIG,	/* FIN0 */
+			   NCT6694_HWMON_FAN_CONFIG,	/* FIN1 */
+			   NCT6694_HWMON_FAN_CONFIG,	/* FIN2 */
+			   NCT6694_HWMON_FAN_CONFIG,	/* FIN3 */
+			   NCT6694_HWMON_FAN_CONFIG,	/* FIN4 */
+			   NCT6694_HWMON_FAN_CONFIG,	/* FIN5 */
+			   NCT6694_HWMON_FAN_CONFIG,	/* FIN6 */
+			   NCT6694_HWMON_FAN_CONFIG,	/* FIN7 */
+			   NCT6694_HWMON_FAN_CONFIG,	/* FIN8 */
+			   NCT6694_HWMON_FAN_CONFIG),	/* FIN9 */
+
+	HWMON_CHANNEL_INFO(pwm,
+			   NCT6694_HWMON_PWM_CONFIG,	/* PWM0 */
+			   NCT6694_HWMON_PWM_CONFIG,	/* PWM1 */
+			   NCT6694_HWMON_PWM_CONFIG,	/* PWM2 */
+			   NCT6694_HWMON_PWM_CONFIG,	/* PWM3 */
+			   NCT6694_HWMON_PWM_CONFIG,	/* PWM4 */
+			   NCT6694_HWMON_PWM_CONFIG,	/* PWM5 */
+			   NCT6694_HWMON_PWM_CONFIG,	/* PWM6 */
+			   NCT6694_HWMON_PWM_CONFIG,	/* PWM7 */
+			   NCT6694_HWMON_PWM_CONFIG,	/* PWM8 */
+			   NCT6694_HWMON_PWM_CONFIG),	/* PWM9 */
+	NULL
+};
+
+static int nct6694_fan_read(struct device *dev, u32 attr, int channel,
+			    long *val)
+{
+	struct nct6694_hwmon_data *data = dev_get_drvdata(dev);
+	unsigned char buf[2];
+	int ret;
+
+	switch (attr) {
+	case hwmon_fan_enable:
+		ret = nct6694_read_msg(data->nct6694, REQUEST_HWMON_MOD,
+				       REQUEST_HWMON_CMD0_OFFSET,
+				       REQUEST_HWMON_CMD0_LEN,
+				       HWMON_FIN_EN(channel / 8),
+				       1, buf);
+		if (ret)
+			return -EINVAL;
+
+		*val = buf[0] & BIT(channel % 8) ? 1 : 0;
+
+		break;
+
+	case hwmon_fan_input:
+		ret = nct6694_read_msg(data->nct6694, REQUEST_RPT_MOD,
+				       HWMON_FIN_IDX(channel), 2, 0,
+				       2, buf);
+		if (ret)
+			return -EINVAL;
+
+		*val = (buf[1] | (buf[0] << 8)) & 0xFFFF;
+
+		break;
+
+	case hwmon_fan_min:
+		ret = nct6694_read_msg(data->nct6694, REQUEST_HWMON_MOD,
+				       REQUEST_HWMON_CMD2_OFFSET,
+				       REQUEST_HWMON_CMD2_LEN,
+				       HWMON_FIN_LIMIT_IDX(channel),
+				       2, buf);
+		if (ret)
+			return -EINVAL;
+
+		*val = (buf[1] | (buf[0] << 8)) & 0xFFFF;
+
+		break;
+
+	case hwmon_fan_min_alarm:
+		ret = nct6694_read_msg(data->nct6694, REQUEST_RPT_MOD,
+				       HWMON_FIN_STS(channel / 8),
+				       1, 0, 1, buf);
+		if (ret)
+			return -EINVAL;
+
+		*val = buf[0] & BIT(channel % 8);
+
+		break;
+
+	default:
+		return -EOPNOTSUPP;
+	}
+
+	return 0;
+}
+
+static int nct6694_pwm_read(struct device *dev, u32 attr, int channel,
+			    long *val)
+{
+	struct nct6694_hwmon_data *data = dev_get_drvdata(dev);
+	unsigned char buf;
+	int ret;
+
+	switch (attr) {
+	case hwmon_pwm_input:
+		ret = nct6694_read_msg(data->nct6694, REQUEST_RPT_MOD,
+				       HWMON_PWM_IDX(channel),
+				       1, 0, 1, &buf);
+		if (ret)
+			return -EINVAL;
+
+		*val = buf;
+
+		break;
+	case hwmon_pwm_freq:
+		ret = nct6694_read_msg(data->nct6694, REQUEST_HWMON_MOD,
+				       REQUEST_HWMON_CMD0_OFFSET,
+				       REQUEST_HWMON_CMD0_LEN,
+				       HWMON_PWM_FREQ_IDX(channel),
+				       1, &buf);
+		if (ret)
+			return -EINVAL;
+
+		*val = buf * 25000 / 255;
+
+		break;
+
+	default:
+		return -EOPNOTSUPP;
+	}
+
+	return 0;
+}
+
+static int nct6694_fan_write(struct device *dev, u32 attr, int channel,
+			     long val)
+{
+	struct nct6694_hwmon_data *data = dev_get_drvdata(dev);
+	unsigned char enable_buf[REQUEST_HWMON_CMD0_LEN] = {0};
+	unsigned char buf[REQUEST_HWMON_CMD2_LEN] = {0};
+	u16 fan_val = (u16)val;
+	int ret;
+
+	switch (attr) {
+	case hwmon_fan_enable:
+		mutex_lock(&data->hwmon_lock);
+		ret = nct6694_read_msg(data->nct6694, REQUEST_HWMON_MOD,
+				       REQUEST_HWMON_CMD0_OFFSET,
+				       REQUEST_HWMON_CMD0_LEN, 0,
+				       REQUEST_HWMON_CMD0_LEN,
+				       enable_buf);
+		if (ret)
+			goto err;
+
+		if (val)
+			enable_buf[HWMON_FIN_EN(channel / 8)] |= BIT(channel % 8);
+		else
+			enable_buf[HWMON_FIN_EN(channel / 8)] &= ~BIT(channel % 8);
+
+		ret = nct6694_write_msg(data->nct6694, REQUEST_HWMON_MOD,
+					REQUEST_HWMON_CMD0_OFFSET,
+					REQUEST_HWMON_CMD0_LEN, enable_buf);
+		if (ret)
+			goto err;
+
+		break;
+
+	case hwmon_fan_min:
+		mutex_lock(&data->hwmon_lock);
+		ret = nct6694_read_msg(data->nct6694, REQUEST_HWMON_MOD,
+				       REQUEST_HWMON_CMD2_OFFSET,
+				       REQUEST_HWMON_CMD2_LEN, 0,
+				       REQUEST_HWMON_CMD2_LEN, buf);
+		if (ret)
+			goto err;
+
+		buf[HWMON_FIN_LIMIT_IDX(channel)] = (u8)((fan_val >> 8) & 0xFF);
+		buf[HWMON_FIN_LIMIT_IDX(channel) + 1] = (u8)(fan_val & 0xFF);
+		ret = nct6694_write_msg(data->nct6694, REQUEST_HWMON_MOD,
+					REQUEST_HWMON_CMD2_OFFSET,
+					REQUEST_HWMON_CMD2_LEN, buf);
+		if (ret)
+			goto err;
+
+		break;
+
+	default:
+		ret = -EOPNOTSUPP;
+		goto err;
+	}
+
+err:
+	mutex_unlock(&data->hwmon_lock);
+	return ret;
+}
+
+static int nct6694_read(struct device *dev, enum hwmon_sensor_types type,
+			u32 attr, int channel, long *val)
+{
+	switch (type) {
+	case hwmon_fan:	/* in RPM */
+		return nct6694_fan_read(dev, attr, channel, val);
+
+	case hwmon_pwm:	/* in value 0~255 */
+		return nct6694_pwm_read(dev, attr, channel, val);
+
+	default:
+		return -EOPNOTSUPP;
+	}
+
+	return 0;
+}
+
+static int nct6694_write(struct device *dev, enum hwmon_sensor_types type,
+			 u32 attr, int channel, long val)
+{
+	switch (type) {
+	case hwmon_fan:
+		return nct6694_fan_write(dev, attr, channel, val);
+	default:
+		return -EOPNOTSUPP;
+	}
+
+	return 0;
+}
+
+static umode_t nct6694_is_visible(const void *data, enum hwmon_sensor_types type,
+				  u32 attr, int channel)
+{
+	switch (type) {
+	case hwmon_fan:
+		switch (attr) {
+		case hwmon_fan_enable:
+		case hwmon_fan_min:
+			return 0644;
+
+		case hwmon_fan_input:
+		case hwmon_fan_min_alarm:
+			return 0444;
+
+		default:
+			return 0;
+		}
+
+	case hwmon_pwm:
+		switch (attr) {
+		case hwmon_pwm_input:
+		case hwmon_pwm_freq:
+			return 0444;
+		default:
+			return 0;
+		}
+
+	default:
+		return 0;
+	}
+
+	return 0;
+}
+
+static const struct hwmon_ops nct6694_hwmon_ops = {
+	.is_visible = nct6694_is_visible,
+	.read = nct6694_read,
+	.write = nct6694_write,
+};
+
+static const struct hwmon_chip_info nct6694_chip_info = {
+	.ops = &nct6694_hwmon_ops,
+	.info = nct6694_info,
+};
+
+static int nct6694_hwmon_init(struct nct6694_hwmon_data *data)
+{
+	unsigned char buf[REQUEST_HWMON_CMD2_LEN] = {0};
+	int ret;
+
+	/* Set Fan input Real Time alarm mode */
+	mutex_lock(&data->hwmon_lock);
+	ret = nct6694_read_msg(data->nct6694, REQUEST_HWMON_MOD,
+			       REQUEST_HWMON_CMD2_OFFSET,
+			       REQUEST_HWMON_CMD2_LEN, 0,
+			       REQUEST_HWMON_CMD2_LEN, buf);
+	if (ret)
+		goto err;
+
+	buf[HWMON_SMI_CTRL_IDX] = 0x02;
+
+	ret = nct6694_write_msg(data->nct6694, REQUEST_HWMON_MOD,
+				REQUEST_HWMON_CMD2_OFFSET,
+				REQUEST_HWMON_CMD2_LEN, buf);
+	if (ret)
+		goto err;
+
+err:
+	mutex_unlock(&data->hwmon_lock);
+	return ret;
+}
+
+static int nct6694_hwmon_probe(struct platform_device *pdev)
+{
+	struct nct6694_hwmon_data *data;
+	struct nct6694 *nct6694 = dev_get_drvdata(pdev->dev.parent);
+	struct device *hwmon_dev;
+	int ret;
+
+	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	data->nct6694 = nct6694;
+	mutex_init(&data->hwmon_lock);
+	platform_set_drvdata(pdev, data);
+
+	ret = nct6694_hwmon_init(data);
+	if (ret)
+		return -EIO;
+
+	/* Register hwmon device to HWMON framework */
+	hwmon_dev = devm_hwmon_device_register_with_info(&pdev->dev,
+							 "nct6694", data,
+							 &nct6694_chip_info,
+							 NULL);
+	if (IS_ERR(hwmon_dev)) {
+		dev_err(&pdev->dev, "%s: Failed to register hwmon device!\n",
+			__func__);
+		return PTR_ERR(hwmon_dev);
+	}
+
+	return 0;
+}
+
+static struct platform_driver nct6694_hwmon_driver = {
+	.driver = {
+		.name	= DRVNAME,
+	},
+	.probe		= nct6694_hwmon_probe,
+};
+
+static int __init nct6694_init(void)
+{
+	int err;
+
+	err = platform_driver_register(&nct6694_hwmon_driver);
+	if (!err) {
+		if (err)
+			platform_driver_unregister(&nct6694_hwmon_driver);
+	}
+
+	return err;
+}
+subsys_initcall(nct6694_init);
+
+static void __exit nct6694_exit(void)
+{
+	platform_driver_unregister(&nct6694_hwmon_driver);
+}
+module_exit(nct6694_exit);
+
+MODULE_DESCRIPTION("USB-HWMON driver for NCT6694");
+MODULE_AUTHOR("Ming Yu <tmyu0@nuvoton.com>");
+MODULE_LICENSE("GPL");