diff mbox series

[v2,5/7] watchdog: Add Nuvoton NCT6694 WDT support

Message ID 20241121064046.3724726-6-tmyu0@nuvoton.com
State Superseded
Headers show
Series Add Nuvoton NCT6694 MFD drivers | expand

Commit Message

Ming Yu Nov. 21, 2024, 6:40 a.m. UTC
This driver supports Watchdog timer functionality for NCT6694 MFD
device based on USB interface.

Signed-off-by: Ming Yu <tmyu0@nuvoton.com>
---
 MAINTAINERS                    |   1 +
 drivers/watchdog/Kconfig       |  11 ++
 drivers/watchdog/Makefile      |   1 +
 drivers/watchdog/nct6694_wdt.c | 277 +++++++++++++++++++++++++++++++++
 4 files changed, 290 insertions(+)
 create mode 100644 drivers/watchdog/nct6694_wdt.c

Comments

Guenter Roeck Nov. 21, 2024, 2:15 p.m. UTC | #1
On 11/20/24 22:40, Ming Yu wrote:
> This driver supports Watchdog timer functionality for NCT6694 MFD
> device based on USB interface.
> 
> Signed-off-by: Ming Yu <tmyu0@nuvoton.com>
> ---
>   MAINTAINERS                    |   1 +
>   drivers/watchdog/Kconfig       |  11 ++
>   drivers/watchdog/Makefile      |   1 +
>   drivers/watchdog/nct6694_wdt.c | 277 +++++++++++++++++++++++++++++++++
>   4 files changed, 290 insertions(+)
>   create mode 100644 drivers/watchdog/nct6694_wdt.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index eb5d46825e71..496fe7d5a23f 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -16549,6 +16549,7 @@ F:	drivers/gpio/gpio-nct6694.c
>   F:	drivers/i2c/busses/i2c-nct6694.c
>   F:	drivers/mfd/nct6694.c
>   F:	drivers/net/can/nct6694_canfd.c
> +F:	drivers/watchdog/nct6694_wdt.c
>   F:	include/linux/mfd/nct6694.h
>   
>   NVIDIA (rivafb and nvidiafb) FRAMEBUFFER DRIVER
> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> index 2333476a42c0..851c1f17712d 100644
> --- a/drivers/watchdog/Kconfig
> +++ b/drivers/watchdog/Kconfig
> @@ -739,6 +739,17 @@ config MAX77620_WATCHDOG
>   	  MAX77620 chips. To compile this driver as a module,
>   	  choose M here: the module will be called max77620_wdt.
>   
> +config NCT6694_WATCHDOG
> +	tristate "Nuvoton NCT6694 watchdog support"
> +	depends on MFD_NCT6694
> +	select WATCHDOG_CORE
> +	help
> +	  If you say yes to this option, support will be included for Nuvoton
> +	  NCT6694, a USB device to watchdog timer.
> +

It is a peripheral expander, not a "USB device to watchdog timer". Watchdog is only
a small part of its functionality.

> +	  This driver can also be built as a module. If so, the module will
> +	  be called nct6694_wdt.
> +
>   config IMX2_WDT
>   	tristate "IMX2+ Watchdog"
>   	depends on ARCH_MXC || ARCH_LAYERSCAPE || COMPILE_TEST
> diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
> index 386d88d89fe5..8355893b4435 100644
> --- a/drivers/watchdog/Makefile
> +++ b/drivers/watchdog/Makefile
> @@ -232,6 +232,7 @@ obj-$(CONFIG_WM831X_WATCHDOG) += wm831x_wdt.o
>   obj-$(CONFIG_WM8350_WATCHDOG) += wm8350_wdt.o
>   obj-$(CONFIG_MAX63XX_WATCHDOG) += max63xx_wdt.o
>   obj-$(CONFIG_MAX77620_WATCHDOG) += max77620_wdt.o
> +obj-$(CONFIG_NCT6694_WATCHDOG)	+= nct6694_wdt.o
>   obj-$(CONFIG_ZIIRAVE_WATCHDOG) += ziirave_wdt.o
>   obj-$(CONFIG_SOFT_WATCHDOG) += softdog.o
>   obj-$(CONFIG_MENF21BMC_WATCHDOG) += menf21bmc_wdt.o
> diff --git a/drivers/watchdog/nct6694_wdt.c b/drivers/watchdog/nct6694_wdt.c
> new file mode 100644
> index 000000000000..7d2c8d5c6fa3
> --- /dev/null
> +++ b/drivers/watchdog/nct6694_wdt.c
> @@ -0,0 +1,277 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Nuvoton NCT6694 WDT driver based on USB interface.
> + *
> + * Copyright (C) 2024 Nuvoton Technology Corp.
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/mfd/core.h>
> +#include <linux/mfd/nct6694.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/slab.h>
> +#include <linux/watchdog.h>
> +
> +#define DRVNAME "nct6694-wdt"
> +
> +#define NCT6694_DEFAULT_TIMEOUT		10
> +#define NCT6694_DEFAULT_PRETIMEOUT	0
> +
> +/* Host interface */
> +#define NCT6694_WDT_MOD		0x07
> +
> +/* Message Channel*/
> +/* Command 00h */
> +#define NCT6694_WDT_CMD0_LEN	0x0F
> +#define NCT6694_WDT_CMD0_OFFSET(idx)	(idx ? 0x0100 : 0x0000)	/* OFFSET = SEL|CMD */
> +
> +/* Command 01h */
> +#define NCT6694_WDT_CMD1_LEN		0x08
> +#define NCT6694_WDT_CMD1_OFFSET(idx)	(idx ? 0x0101 : 0x0001)	/* OFFSET = SEL|CMD */
> +
> +static unsigned int timeout = NCT6694_DEFAULT_TIMEOUT;
> +module_param(timeout, int, 0);
> +MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds");
> +
> +static unsigned int pretimeout = NCT6694_DEFAULT_PRETIMEOUT;
> +module_param(pretimeout, int, 0);
> +MODULE_PARM_DESC(pretimeout, "Watchdog pre-timeout in seconds");
> +
> +static bool nowayout = WATCHDOG_NOWAYOUT;
> +module_param(nowayout, bool, 0);
> +MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
> +			   __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
> +
> +enum {
> +	NCT6694_ACTION_NONE = 0,
> +	NCT6694_ACTION_SIRQ,
> +	NCT6694_ACTION_GPO,
> +};
> +
> +struct __packed nct6694_wdt_cmd0 {
> +	__le32 pretimeout;
> +	__le32 timeout;
> +	u8 owner;
> +	u8 scratch;
> +	u8 control;
> +	u8 status;
> +	__le32 countdown;
> +};
> +
> +struct __packed nct6694_wdt_cmd1 {
> +	u32 wdt_cmd;
> +	u32 reserved;
> +};
> +
> +struct nct6694_wdt_data {
> +	struct watchdog_device wdev;
> +	struct device *dev;
> +	struct nct6694 *nct6694;
> +	struct mutex lock;
> +	unsigned char *xmit_buf;
> +	unsigned int wdev_idx;
> +};
> +
> +static int nct6694_wdt_setting(struct watchdog_device *wdev,
> +			       u32 timeout_val, u8 timeout_act,
> +			       u32 pretimeout_val, u8 pretimeout_act)
> +{
> +	struct nct6694_wdt_data *data = watchdog_get_drvdata(wdev);
> +	struct nct6694_wdt_cmd0 *buf = (struct nct6694_wdt_cmd0 *)data->xmit_buf;
> +	struct nct6694 *nct6694 = data->nct6694;
> +	unsigned int timeout_fmt, pretimeout_fmt;
> +
> +	guard(mutex)(&data->lock);
> +
> +	if (pretimeout_val == 0)
> +		pretimeout_act = NCT6694_ACTION_NONE;
> +
> +	timeout_fmt = (timeout_val * 1000) | (timeout_act << 24);
> +	pretimeout_fmt = (pretimeout_val * 1000) | (pretimeout_act << 24);
> +
> +	memset(buf, 0, NCT6694_WDT_CMD0_LEN);
> +	buf->timeout = cpu_to_le32(timeout_fmt);
> +	buf->pretimeout = cpu_to_le32(pretimeout_fmt);
> +
> +	return nct6694_write_msg(nct6694, NCT6694_WDT_MOD,
> +				 NCT6694_WDT_CMD0_OFFSET(data->wdev_idx),
> +				 NCT6694_WDT_CMD0_LEN, buf);
> +}
> +
> +static int nct6694_wdt_start(struct watchdog_device *wdev)
> +{
> +	struct nct6694_wdt_data *data = watchdog_get_drvdata(wdev);
> +	int ret;
> +
> +	ret = nct6694_wdt_setting(wdev, wdev->timeout, NCT6694_ACTION_GPO,
> +				  wdev->pretimeout, NCT6694_ACTION_GPO);
> +	if (ret)
> +		return ret;
> +
> +	dev_info(data->dev, "Setting WDT(%d): timeout = %d, pretimeout = %d\n",
> +		 data->wdev_idx, wdev->timeout, wdev->pretimeout);
> +

This is logging noise. Drop or set as debug message.

> +	return ret;
> +}
> +
> +static int nct6694_wdt_stop(struct watchdog_device *wdev)
> +{
> +	struct nct6694_wdt_data *data = watchdog_get_drvdata(wdev);
> +	struct nct6694_wdt_cmd1 *buf = (struct nct6694_wdt_cmd1 *)data->xmit_buf;
> +	struct nct6694 *nct6694 = data->nct6694;
> +
> +	guard(mutex)(&data->lock);
> +
> +	memcpy(buf, "WDTC", 4);
> +	buf->reserved = 0;
> +
> +	return nct6694_write_msg(nct6694, NCT6694_WDT_MOD,
> +				 NCT6694_WDT_CMD1_OFFSET(data->wdev_idx),
> +				 NCT6694_WDT_CMD1_LEN, buf);
> +}
> +
> +static int nct6694_wdt_ping(struct watchdog_device *wdev)
> +{
> +	struct nct6694_wdt_data *data = watchdog_get_drvdata(wdev);
> +	struct nct6694_wdt_cmd1 *buf = (struct nct6694_wdt_cmd1 *)data->xmit_buf;
> +	struct nct6694 *nct6694 = data->nct6694;
> +
> +	guard(mutex)(&data->lock);
> +	memcpy(buf, "WDTS", 4);
> +	buf->reserved = 0;
> +
> +	return nct6694_write_msg(nct6694, NCT6694_WDT_MOD,
> +				 NCT6694_WDT_CMD1_OFFSET(data->wdev_idx),
> +				 NCT6694_WDT_CMD1_LEN, buf);
> +}
> +
> +static int nct6694_wdt_set_timeout(struct watchdog_device *wdev,
> +				   unsigned int timeout)
> +{
> +	struct nct6694_wdt_data *data = watchdog_get_drvdata(wdev);
> +	int ret;
> +
> +	if (timeout < wdev->pretimeout) {
> +		dev_warn(data->dev, "pretimeout < timeout. Setting to zero\n");
> +		wdev->pretimeout = 0;
> +	}
> +
This is only necessary if the pretimeout was not validated during probe
since otherwise the watchdog core does the check. Please validate it there.

> +	ret = nct6694_wdt_setting(wdev, timeout, NCT6694_ACTION_GPO,
> +				  wdev->pretimeout, NCT6694_ACTION_GPO);
> +	if (ret)
> +		return ret;
> +
> +	wdev->timeout = timeout;
> +
> +	return ret;

ret == 0 here, so return 0.

> +}
> +
> +static int nct6694_wdt_set_pretimeout(struct watchdog_device *wdev,
> +				      unsigned int pretimeout)
> +{
> +	int ret;
> +
> +	ret = nct6694_wdt_setting(wdev, wdev->timeout, NCT6694_ACTION_GPO,
> +				  pretimeout, NCT6694_ACTION_GPO);
> +	if (ret)
> +		return ret;
> +
> +	wdev->pretimeout = pretimeout;
> +
> +	return ret;

ret == 0 here, so return 0.

> +}
> +
> +static unsigned int nct6694_wdt_get_time(struct watchdog_device *wdev)
> +{
> +	struct nct6694_wdt_data *data = watchdog_get_drvdata(wdev);
> +	struct nct6694_wdt_cmd0 *buf = (struct nct6694_wdt_cmd0 *)data->xmit_buf;
> +	struct nct6694 *nct6694 = data->nct6694;
> +	unsigned int timeleft_ms;
> +	int ret;
> +
> +	guard(mutex)(&data->lock);
> +
> +	ret = nct6694_read_msg(nct6694, NCT6694_WDT_MOD,
> +			       NCT6694_WDT_CMD0_OFFSET(data->wdev_idx),
> +			       NCT6694_WDT_CMD0_LEN, buf);
> +	if (ret)
> +		return ret;

The function does not return an error code. Return 0 instead.
> +
> +	timeleft_ms = le32_to_cpu(buf->countdown);
> +
> +	return timeleft_ms / 1000;
> +}
> +
> +static const struct watchdog_info nct6694_wdt_info = {
> +	.options = WDIOF_SETTIMEOUT	|
> +		   WDIOF_KEEPALIVEPING	|
> +		   WDIOF_MAGICCLOSE	|
> +		   WDIOF_PRETIMEOUT,
> +	.identity = DRVNAME,
> +};
> +
> +static const struct watchdog_ops nct6694_wdt_ops = {
> +	.owner = THIS_MODULE,
> +	.start = nct6694_wdt_start,
> +	.stop = nct6694_wdt_stop,
> +	.set_timeout = nct6694_wdt_set_timeout,
> +	.set_pretimeout = nct6694_wdt_set_pretimeout,
> +	.get_timeleft = nct6694_wdt_get_time,
> +	.ping = nct6694_wdt_ping,
> +};
> +
> +static int nct6694_wdt_probe(struct platform_device *pdev)
> +{
> +	const struct mfd_cell *cell = mfd_get_cell(pdev);
> +	struct device *dev = &pdev->dev;
> +	struct nct6694 *nct6694 = dev_get_drvdata(pdev->dev.parent);
> +	struct nct6694_wdt_data *data;
> +	struct watchdog_device *wdev;
> +
> +	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
> +	if (!data)
> +		return -ENOMEM;
> +
> +	data->xmit_buf = devm_kcalloc(dev, NCT6694_MAX_PACKET_SZ,
> +				      sizeof(unsigned char), GFP_KERNEL);
> +	if (!data->xmit_buf)
> +		return -ENOMEM;
> +
> +	data->dev = dev;
> +	data->nct6694 = nct6694;
> +	data->wdev_idx = cell->id;
> +
> +	wdev = &data->wdev;
> +	wdev->info = &nct6694_wdt_info;
> +	wdev->ops = &nct6694_wdt_ops;
> +	wdev->timeout = timeout;
> +	wdev->pretimeout = pretimeout;

pretimeout should be validated here.

> +	wdev->min_timeout = 1;
> +	wdev->max_timeout = 255;
> +
> +	mutex_init(&data->lock);
> +
> +	platform_set_drvdata(pdev, data);
> +
> +	/* Register watchdog timer device to WDT framework */
> +	watchdog_set_drvdata(&data->wdev, data);
> +	watchdog_init_timeout(&data->wdev, timeout, dev);
> +	watchdog_set_nowayout(&data->wdev, nowayout);
> +	watchdog_stop_on_reboot(&data->wdev);
> +
> +	return devm_watchdog_register_device(dev, &data->wdev);
> +}
> +
> +static struct platform_driver nct6694_wdt_driver = {
> +	.driver = {
> +		.name	= DRVNAME,
> +	},
> +	.probe		= nct6694_wdt_probe,
> +};
> +
> +module_platform_driver(nct6694_wdt_driver);
> +
> +MODULE_DESCRIPTION("USB-WDT driver for NCT6694");
> +MODULE_AUTHOR("Ming Yu <tmyu0@nuvoton.com>");
> +MODULE_LICENSE("GPL");
Ming Yu Nov. 22, 2024, 8:11 a.m. UTC | #2
Dear Guenter,

Thank you for your comments,

Guenter Roeck <linux@roeck-us.net> 於 2024年11月21日 週四 下午10:15寫道:
> > +config NCT6694_WATCHDOG
> > +     tristate "Nuvoton NCT6694 watchdog support"
> > +     depends on MFD_NCT6694
> > +     select WATCHDOG_CORE
> > +     help
> > +       If you say yes to this option, support will be included for Nuvoton
> > +       NCT6694, a USB device to watchdog timer.
> > +
>
> It is a peripheral expander, not a "USB device to watchdog timer". Watchdog is only
> a small part of its functionality.
>

Understood. I will make the modifications in v3.

> > +       This driver can also be built as a module. If so, the module will
> > +       be called nct6694_wdt.
...
> > +     ret = nct6694_wdt_setting(wdev, wdev->timeout, NCT6694_ACTION_GPO,
> > +                               wdev->pretimeout, NCT6694_ACTION_GPO);
> > +     if (ret)
> > +             return ret;
> > +
> > +     dev_info(data->dev, "Setting WDT(%d): timeout = %d, pretimeout = %d\n",
> > +              data->wdev_idx, wdev->timeout, wdev->pretimeout);
> > +
>
> This is logging noise. Drop or set as debug message.
>

Okay, I'll drop it in v3.

> > +     return ret;
> > +}
...
> > +static int nct6694_wdt_set_timeout(struct watchdog_device *wdev,
> > +                                unsigned int timeout)
> > +{
> > +     struct nct6694_wdt_data *data = watchdog_get_drvdata(wdev);
> > +     int ret;
> > +
> > +     if (timeout < wdev->pretimeout) {
> > +             dev_warn(data->dev, "pretimeout < timeout. Setting to zero\n");
> > +             wdev->pretimeout = 0;
> > +     }
> > +
> This is only necessary if the pretimeout was not validated during probe
> since otherwise the watchdog core does the check. Please validate it there.
>

Understood. I will make the modifications in v3.

> > +     ret = nct6694_wdt_setting(wdev, timeout, NCT6694_ACTION_GPO,
> > +                               wdev->pretimeout, NCT6694_ACTION_GPO);
> > +     if (ret)
> > +             return ret;
> > +
> > +     wdev->timeout = timeout;
> > +
> > +     return ret;
>
> ret == 0 here, so return 0.
>

Okay, fix it in v3.

> > +}
> > +
> > +static int nct6694_wdt_set_pretimeout(struct watchdog_device *wdev,
> > +                                   unsigned int pretimeout)
> > +{
> > +     int ret;
> > +
> > +     ret = nct6694_wdt_setting(wdev, wdev->timeout, NCT6694_ACTION_GPO,
> > +                               pretimeout, NCT6694_ACTION_GPO);
> > +     if (ret)
> > +             return ret;
> > +
> > +     wdev->pretimeout = pretimeout;
> > +
> > +     return ret;
>
> ret == 0 here, so return 0.
>

Okay, fix it in v3.

> > +}
> > +
> > +static unsigned int nct6694_wdt_get_time(struct watchdog_device *wdev)
> > +{
> > +     struct nct6694_wdt_data *data = watchdog_get_drvdata(wdev);
> > +     struct nct6694_wdt_cmd0 *buf = (struct nct6694_wdt_cmd0 *)data->xmit_buf;
> > +     struct nct6694 *nct6694 = data->nct6694;
> > +     unsigned int timeleft_ms;
> > +     int ret;
> > +
> > +     guard(mutex)(&data->lock);
> > +
> > +     ret = nct6694_read_msg(nct6694, NCT6694_WDT_MOD,
> > +                            NCT6694_WDT_CMD0_OFFSET(data->wdev_idx),
> > +                            NCT6694_WDT_CMD0_LEN, buf);
> > +     if (ret)
> > +             return ret;
>
> The function does not return an error code. Return 0 instead.

Okay, fix it in v3.

> > +
> > +     timeleft_ms = le32_to_cpu(buf->countdown);
> > +
> > +     return timeleft_ms / 1000;
> > +}
...
> > +     wdev = &data->wdev;
> > +     wdev->info = &nct6694_wdt_info;
> > +     wdev->ops = &nct6694_wdt_ops;
> > +     wdev->timeout = timeout;
> > +     wdev->pretimeout = pretimeout;
>
> pretimeout should be validated here.
>

Understood. I will make the modifications in v3.

Best regards,
Ming
diff mbox series

Patch

diff --git a/MAINTAINERS b/MAINTAINERS
index eb5d46825e71..496fe7d5a23f 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -16549,6 +16549,7 @@  F:	drivers/gpio/gpio-nct6694.c
 F:	drivers/i2c/busses/i2c-nct6694.c
 F:	drivers/mfd/nct6694.c
 F:	drivers/net/can/nct6694_canfd.c
+F:	drivers/watchdog/nct6694_wdt.c
 F:	include/linux/mfd/nct6694.h
 
 NVIDIA (rivafb and nvidiafb) FRAMEBUFFER DRIVER
diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 2333476a42c0..851c1f17712d 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -739,6 +739,17 @@  config MAX77620_WATCHDOG
 	  MAX77620 chips. To compile this driver as a module,
 	  choose M here: the module will be called max77620_wdt.
 
+config NCT6694_WATCHDOG
+	tristate "Nuvoton NCT6694 watchdog support"
+	depends on MFD_NCT6694
+	select WATCHDOG_CORE
+	help
+	  If you say yes to this option, support will be included for Nuvoton
+	  NCT6694, a USB device to watchdog timer.
+
+	  This driver can also be built as a module. If so, the module will
+	  be called nct6694_wdt.
+
 config IMX2_WDT
 	tristate "IMX2+ Watchdog"
 	depends on ARCH_MXC || ARCH_LAYERSCAPE || COMPILE_TEST
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index 386d88d89fe5..8355893b4435 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -232,6 +232,7 @@  obj-$(CONFIG_WM831X_WATCHDOG) += wm831x_wdt.o
 obj-$(CONFIG_WM8350_WATCHDOG) += wm8350_wdt.o
 obj-$(CONFIG_MAX63XX_WATCHDOG) += max63xx_wdt.o
 obj-$(CONFIG_MAX77620_WATCHDOG) += max77620_wdt.o
+obj-$(CONFIG_NCT6694_WATCHDOG)	+= nct6694_wdt.o
 obj-$(CONFIG_ZIIRAVE_WATCHDOG) += ziirave_wdt.o
 obj-$(CONFIG_SOFT_WATCHDOG) += softdog.o
 obj-$(CONFIG_MENF21BMC_WATCHDOG) += menf21bmc_wdt.o
diff --git a/drivers/watchdog/nct6694_wdt.c b/drivers/watchdog/nct6694_wdt.c
new file mode 100644
index 000000000000..7d2c8d5c6fa3
--- /dev/null
+++ b/drivers/watchdog/nct6694_wdt.c
@@ -0,0 +1,277 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Nuvoton NCT6694 WDT driver based on USB interface.
+ *
+ * Copyright (C) 2024 Nuvoton Technology Corp.
+ */
+
+#include <linux/kernel.h>
+#include <linux/mfd/core.h>
+#include <linux/mfd/nct6694.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/watchdog.h>
+
+#define DRVNAME "nct6694-wdt"
+
+#define NCT6694_DEFAULT_TIMEOUT		10
+#define NCT6694_DEFAULT_PRETIMEOUT	0
+
+/* Host interface */
+#define NCT6694_WDT_MOD		0x07
+
+/* Message Channel*/
+/* Command 00h */
+#define NCT6694_WDT_CMD0_LEN	0x0F
+#define NCT6694_WDT_CMD0_OFFSET(idx)	(idx ? 0x0100 : 0x0000)	/* OFFSET = SEL|CMD */
+
+/* Command 01h */
+#define NCT6694_WDT_CMD1_LEN		0x08
+#define NCT6694_WDT_CMD1_OFFSET(idx)	(idx ? 0x0101 : 0x0001)	/* OFFSET = SEL|CMD */
+
+static unsigned int timeout = NCT6694_DEFAULT_TIMEOUT;
+module_param(timeout, int, 0);
+MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds");
+
+static unsigned int pretimeout = NCT6694_DEFAULT_PRETIMEOUT;
+module_param(pretimeout, int, 0);
+MODULE_PARM_DESC(pretimeout, "Watchdog pre-timeout in seconds");
+
+static bool nowayout = WATCHDOG_NOWAYOUT;
+module_param(nowayout, bool, 0);
+MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
+			   __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
+
+enum {
+	NCT6694_ACTION_NONE = 0,
+	NCT6694_ACTION_SIRQ,
+	NCT6694_ACTION_GPO,
+};
+
+struct __packed nct6694_wdt_cmd0 {
+	__le32 pretimeout;
+	__le32 timeout;
+	u8 owner;
+	u8 scratch;
+	u8 control;
+	u8 status;
+	__le32 countdown;
+};
+
+struct __packed nct6694_wdt_cmd1 {
+	u32 wdt_cmd;
+	u32 reserved;
+};
+
+struct nct6694_wdt_data {
+	struct watchdog_device wdev;
+	struct device *dev;
+	struct nct6694 *nct6694;
+	struct mutex lock;
+	unsigned char *xmit_buf;
+	unsigned int wdev_idx;
+};
+
+static int nct6694_wdt_setting(struct watchdog_device *wdev,
+			       u32 timeout_val, u8 timeout_act,
+			       u32 pretimeout_val, u8 pretimeout_act)
+{
+	struct nct6694_wdt_data *data = watchdog_get_drvdata(wdev);
+	struct nct6694_wdt_cmd0 *buf = (struct nct6694_wdt_cmd0 *)data->xmit_buf;
+	struct nct6694 *nct6694 = data->nct6694;
+	unsigned int timeout_fmt, pretimeout_fmt;
+
+	guard(mutex)(&data->lock);
+
+	if (pretimeout_val == 0)
+		pretimeout_act = NCT6694_ACTION_NONE;
+
+	timeout_fmt = (timeout_val * 1000) | (timeout_act << 24);
+	pretimeout_fmt = (pretimeout_val * 1000) | (pretimeout_act << 24);
+
+	memset(buf, 0, NCT6694_WDT_CMD0_LEN);
+	buf->timeout = cpu_to_le32(timeout_fmt);
+	buf->pretimeout = cpu_to_le32(pretimeout_fmt);
+
+	return nct6694_write_msg(nct6694, NCT6694_WDT_MOD,
+				 NCT6694_WDT_CMD0_OFFSET(data->wdev_idx),
+				 NCT6694_WDT_CMD0_LEN, buf);
+}
+
+static int nct6694_wdt_start(struct watchdog_device *wdev)
+{
+	struct nct6694_wdt_data *data = watchdog_get_drvdata(wdev);
+	int ret;
+
+	ret = nct6694_wdt_setting(wdev, wdev->timeout, NCT6694_ACTION_GPO,
+				  wdev->pretimeout, NCT6694_ACTION_GPO);
+	if (ret)
+		return ret;
+
+	dev_info(data->dev, "Setting WDT(%d): timeout = %d, pretimeout = %d\n",
+		 data->wdev_idx, wdev->timeout, wdev->pretimeout);
+
+	return ret;
+}
+
+static int nct6694_wdt_stop(struct watchdog_device *wdev)
+{
+	struct nct6694_wdt_data *data = watchdog_get_drvdata(wdev);
+	struct nct6694_wdt_cmd1 *buf = (struct nct6694_wdt_cmd1 *)data->xmit_buf;
+	struct nct6694 *nct6694 = data->nct6694;
+
+	guard(mutex)(&data->lock);
+
+	memcpy(buf, "WDTC", 4);
+	buf->reserved = 0;
+
+	return nct6694_write_msg(nct6694, NCT6694_WDT_MOD,
+				 NCT6694_WDT_CMD1_OFFSET(data->wdev_idx),
+				 NCT6694_WDT_CMD1_LEN, buf);
+}
+
+static int nct6694_wdt_ping(struct watchdog_device *wdev)
+{
+	struct nct6694_wdt_data *data = watchdog_get_drvdata(wdev);
+	struct nct6694_wdt_cmd1 *buf = (struct nct6694_wdt_cmd1 *)data->xmit_buf;
+	struct nct6694 *nct6694 = data->nct6694;
+
+	guard(mutex)(&data->lock);
+	memcpy(buf, "WDTS", 4);
+	buf->reserved = 0;
+
+	return nct6694_write_msg(nct6694, NCT6694_WDT_MOD,
+				 NCT6694_WDT_CMD1_OFFSET(data->wdev_idx),
+				 NCT6694_WDT_CMD1_LEN, buf);
+}
+
+static int nct6694_wdt_set_timeout(struct watchdog_device *wdev,
+				   unsigned int timeout)
+{
+	struct nct6694_wdt_data *data = watchdog_get_drvdata(wdev);
+	int ret;
+
+	if (timeout < wdev->pretimeout) {
+		dev_warn(data->dev, "pretimeout < timeout. Setting to zero\n");
+		wdev->pretimeout = 0;
+	}
+
+	ret = nct6694_wdt_setting(wdev, timeout, NCT6694_ACTION_GPO,
+				  wdev->pretimeout, NCT6694_ACTION_GPO);
+	if (ret)
+		return ret;
+
+	wdev->timeout = timeout;
+
+	return ret;
+}
+
+static int nct6694_wdt_set_pretimeout(struct watchdog_device *wdev,
+				      unsigned int pretimeout)
+{
+	int ret;
+
+	ret = nct6694_wdt_setting(wdev, wdev->timeout, NCT6694_ACTION_GPO,
+				  pretimeout, NCT6694_ACTION_GPO);
+	if (ret)
+		return ret;
+
+	wdev->pretimeout = pretimeout;
+
+	return ret;
+}
+
+static unsigned int nct6694_wdt_get_time(struct watchdog_device *wdev)
+{
+	struct nct6694_wdt_data *data = watchdog_get_drvdata(wdev);
+	struct nct6694_wdt_cmd0 *buf = (struct nct6694_wdt_cmd0 *)data->xmit_buf;
+	struct nct6694 *nct6694 = data->nct6694;
+	unsigned int timeleft_ms;
+	int ret;
+
+	guard(mutex)(&data->lock);
+
+	ret = nct6694_read_msg(nct6694, NCT6694_WDT_MOD,
+			       NCT6694_WDT_CMD0_OFFSET(data->wdev_idx),
+			       NCT6694_WDT_CMD0_LEN, buf);
+	if (ret)
+		return ret;
+
+	timeleft_ms = le32_to_cpu(buf->countdown);
+
+	return timeleft_ms / 1000;
+}
+
+static const struct watchdog_info nct6694_wdt_info = {
+	.options = WDIOF_SETTIMEOUT	|
+		   WDIOF_KEEPALIVEPING	|
+		   WDIOF_MAGICCLOSE	|
+		   WDIOF_PRETIMEOUT,
+	.identity = DRVNAME,
+};
+
+static const struct watchdog_ops nct6694_wdt_ops = {
+	.owner = THIS_MODULE,
+	.start = nct6694_wdt_start,
+	.stop = nct6694_wdt_stop,
+	.set_timeout = nct6694_wdt_set_timeout,
+	.set_pretimeout = nct6694_wdt_set_pretimeout,
+	.get_timeleft = nct6694_wdt_get_time,
+	.ping = nct6694_wdt_ping,
+};
+
+static int nct6694_wdt_probe(struct platform_device *pdev)
+{
+	const struct mfd_cell *cell = mfd_get_cell(pdev);
+	struct device *dev = &pdev->dev;
+	struct nct6694 *nct6694 = dev_get_drvdata(pdev->dev.parent);
+	struct nct6694_wdt_data *data;
+	struct watchdog_device *wdev;
+
+	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	data->xmit_buf = devm_kcalloc(dev, NCT6694_MAX_PACKET_SZ,
+				      sizeof(unsigned char), GFP_KERNEL);
+	if (!data->xmit_buf)
+		return -ENOMEM;
+
+	data->dev = dev;
+	data->nct6694 = nct6694;
+	data->wdev_idx = cell->id;
+
+	wdev = &data->wdev;
+	wdev->info = &nct6694_wdt_info;
+	wdev->ops = &nct6694_wdt_ops;
+	wdev->timeout = timeout;
+	wdev->pretimeout = pretimeout;
+	wdev->min_timeout = 1;
+	wdev->max_timeout = 255;
+
+	mutex_init(&data->lock);
+
+	platform_set_drvdata(pdev, data);
+
+	/* Register watchdog timer device to WDT framework */
+	watchdog_set_drvdata(&data->wdev, data);
+	watchdog_init_timeout(&data->wdev, timeout, dev);
+	watchdog_set_nowayout(&data->wdev, nowayout);
+	watchdog_stop_on_reboot(&data->wdev);
+
+	return devm_watchdog_register_device(dev, &data->wdev);
+}
+
+static struct platform_driver nct6694_wdt_driver = {
+	.driver = {
+		.name	= DRVNAME,
+	},
+	.probe		= nct6694_wdt_probe,
+};
+
+module_platform_driver(nct6694_wdt_driver);
+
+MODULE_DESCRIPTION("USB-WDT driver for NCT6694");
+MODULE_AUTHOR("Ming Yu <tmyu0@nuvoton.com>");
+MODULE_LICENSE("GPL");