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

Ming Yu
2024-10-25T15:33:50Z

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");
>