Message-ID: <5fa97399-25b8-4877-be6e-69ba1ae1837d@roeck-us.net>
Date: Thu, 24 Oct 2024 08:32:58 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: Ming Yu <a0282524688@...il.com>, tmyu0@...oton.com, lee@...nel.org,
 linus.walleij@...aro.org, brgl@...ev.pl, andi.shyti@...nel.org,
 mkl@...gutronix.de, mailhol.vincent@...adoo.fr, andrew+netdev@...n.ch,
 davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
 pabeni@...hat.com, wim@...ux-watchdog.org, jdelvare@...e.com,
 jic23@...nel.org, lars@...afoo.de, ukleinek@...nel.org,
 alexandre.belloni@...tlin.com
Cc: linux-kernel@...r.kernel.org, linux-gpio@...r.kernel.org,
 linux-i2c@...r.kernel.org, linux-can@...r.kernel.org,
 netdev@...r.kernel.org, linux-watchdog@...r.kernel.org,
 linux-hwmon@...r.kernel.org, linux-iio@...r.kernel.org,
 linux-pwm@...r.kernel.org, linux-rtc@...r.kernel.org
Subject: Re: [PATCH v1 5/9] watchdog: Add Nuvoton NCT6694 WDT support

On 10/24/24 01:59, Ming Yu wrote:
> This driver supports Watchdog timer functionality for NCT6694 MFD
> device based on USB interface.
> 
> Signed-off-by: Ming Yu <tmyu0@...oton.com>
> ---
>   MAINTAINERS                    |   1 +
>   drivers/watchdog/Kconfig       |  11 ++
>   drivers/watchdog/Makefile      |   1 +
>   drivers/watchdog/nct6694_wdt.c | 329 +++++++++++++++++++++++++++++++++
>   4 files changed, 342 insertions(+)
>   create mode 100644 drivers/watchdog/nct6694_wdt.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index eccd5e795daa..63387c0d4ab6 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -16442,6 +16442,7 @@ 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 684b9fe84fff..bc9d63d69204 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 ab6f2b41e38e..453ceacd43ab 100644
> --- a/drivers/watchdog/Makefile
> +++ b/drivers/watchdog/Makefile
> @@ -231,6 +231,7 @@ 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..68e2926ec504
> --- /dev/null
> +++ b/drivers/watchdog/nct6694_wdt.c
> @@ -0,0 +1,329 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Nuvoton NCT6694 WDT driver based on USB interface.
> + *
> + * Copyright (C) 2024 Nuvoton Technology Corp.
> + */
> +
> +#include <linux/watchdog.h>
> +#include <linux/slab.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/mfd/core.h>
> +#include <linux/platform_device.h>
> +#include <linux/mfd/nct6694.h>
> +
> +#define DRVNAME "nct6694-wdt"
> +
> +#define WATCHDOG_TIMEOUT	10
> +#define WATCHDOG_PRETIMEOUT	0
> +
> +/* Host interface */
> +#define REQUEST_WDT_MOD		0x07
> +
> +/* Message Channel*/
> +/* Command 00h */
> +#define REQUEST_WDT_CMD0_LEN	0x0F
> +#define REQUEST_WDT_CMD0_OFFSET(idx)	(idx ? 0x0100 : 0x0000)	/* OFFSET = SEL|CMD */
> +#define WDT_PRETIMEOUT_IDX	0x00
> +#define WDT_PRETIMEOUT_LEN	0x04	/* PRETIMEOUT(3byte) | ACT(1byte) */
> +#define WDT_TIMEOUT_IDX		0x04
> +#define WDT_TIMEOUT_LEN		0x04	/* TIMEOUT(3byte) | ACT(1byte) */
> +#define WDT_COUNTDOWN_IDX	0x0C
> +#define WDT_COUNTDOWN_LEN	0x03
> +
> +#define WDT_PRETIMEOUT_ACT	BIT(1)
> +#define WDT_TIMEOUT_ACT		BIT(1)
> +
> +/* Command 01h */
> +#define REQUEST_WDT_CMD1_LEN		0x04
> +#define REQUEST_WDT_CMD1_OFFSET(idx)	(idx ? 0x0101 : 0x0001)	/* OFFSET = SEL|CMD */
> +#define WDT_CMD_IDX			0x00
> +#define WDT_CMD_LEN			0x04
> +
> +static unsigned int timeout;
> +module_param(timeout, int, 0);
> +MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds");
> +
> +static unsigned int 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) ")");
> +
> +struct nct6694_wdt_data {
> +	struct nct6694 *nct6694;
> +	struct watchdog_device wdev;
> +	unsigned int wdev_idx;
> +};
> +
> +static inline void set_buf32(void *buf, u32 u32_val)
> +{
> +	u8 *p = (u8 *)buf;
> +
> +	p[0] = u32_val & 0xFF;
> +	p[1] = (u32_val >> 8) & 0xFF;
> +	p[2] = (u32_val >> 16) & 0xFF;
> +	p[3] = (u32_val >> 24) & 0xFF;
> +}
> +
> +static int nct6694_wdt_start(struct watchdog_device *wdev)
> +{
> +	struct nct6694_wdt_data *data = watchdog_get_drvdata(wdev);
> +
> +	pr_debug("%s: WDT(%d) Start\n", __func__, data->wdev_idx);
> +
> +	return 0;
> +}
> +
> +static int nct6694_wdt_stop(struct watchdog_device *wdev)
> +{
> +	struct nct6694_wdt_data *data = watchdog_get_drvdata(wdev);
> +	struct nct6694 *nct6694 = data->nct6694;
> +	unsigned char buf[REQUEST_WDT_CMD1_LEN] = {'W', 'D', 'T', 'C'};
> +	int ret;
> +
> +	pr_debug("%s: WDT(%d) Close\n", __func__, data->wdev_idx);
> +	ret = nct6694_write_msg(nct6694, REQUEST_WDT_MOD,
> +				REQUEST_WDT_CMD1_OFFSET(data->wdev_idx),
> +				REQUEST_WDT_CMD1_LEN, buf);
> +	if (ret)
> +		pr_err("%s: Failed to start WDT device!\n", __func__);

Please refrain from logging noise. Besides, the message is wrong:
the watchdog is stopped here, not started.

Also, all messages should use dev_, not pr_ functions.

> +
> +	return ret;
> +}
> +
> +static int nct6694_wdt_ping(struct watchdog_device *wdev)
> +{
> +	struct nct6694_wdt_data *data = watchdog_get_drvdata(wdev);
> +	struct nct6694 *nct6694 = data->nct6694;
> +	unsigned char buf[REQUEST_WDT_CMD1_LEN] = {'W', 'D', 'T', 'S'};
> +	int ret;
> +
> +	pr_debug("%s: WDT(%d) Ping\n", __func__, data->wdev_idx);
> +	ret = nct6694_write_msg(nct6694, REQUEST_WDT_MOD,
> +				REQUEST_WDT_CMD1_OFFSET(data->wdev_idx),
> +				REQUEST_WDT_CMD1_LEN, buf);
> +	if (ret)
> +		pr_err("%s: Failed to ping WDT device!\n", __func__);

Same as above and everywhere else.

> +
> +	return ret;
> +}
> +
> +static int nct6694_wdt_set_timeout(struct watchdog_device *wdev,
> +				   unsigned int timeout)
> +{
> +	struct nct6694_wdt_data *data = watchdog_get_drvdata(wdev);
> +	struct nct6694 *nct6694 = data->nct6694;
> +	unsigned int timeout_fmt, pretimeout_fmt;
> +	unsigned char buf[REQUEST_WDT_CMD0_LEN];
> +	int ret;
> +
> +	if (timeout < wdev->pretimeout) {
> +		pr_err("%s: 'timeout' must be greater than 'pre timeout'!\n",
> +		       __func__);
> +		return -EINVAL;

the driver is supposed to adjust pretimeout in this case. And please,
again, refrain from logging noise.
> +	}
> +
> +	timeout_fmt = timeout * 1000 | (WDT_TIMEOUT_ACT << 24);
> +	pretimeout_fmt = wdev->pretimeout * 1000 | (WDT_PRETIMEOUT_ACT << 24);
> +	set_buf32(&buf[WDT_TIMEOUT_IDX], le32_to_cpu(timeout_fmt));
> +	set_buf32(&buf[WDT_PRETIMEOUT_IDX], le32_to_cpu(pretimeout_fmt));
> +
> +	ret = nct6694_write_msg(nct6694, REQUEST_WDT_MOD,
> +				REQUEST_WDT_CMD0_OFFSET(data->wdev_idx),
> +				REQUEST_WDT_CMD0_LEN, buf);
> +	if (ret) {
> +		pr_err("%s: Don't write the setup command in Start stage!\n",
> +		       __func__);
> +		return ret;
> +	}
> +
> +	wdev->timeout = timeout;
> +
> +	return 0;
> +}
> +
> +static int nct6694_wdt_set_pretimeout(struct watchdog_device *wdev,
> +				      unsigned int pretimeout)
> +{
> +	struct nct6694_wdt_data *data = watchdog_get_drvdata(wdev);
> +	struct nct6694 *nct6694 = data->nct6694;
> +	unsigned int timeout_fmt, pretimeout_fmt;
> +	unsigned char buf[REQUEST_WDT_CMD0_LEN];
> +	int ret;
> +
> +	if (pretimeout > wdev->timeout) {
> +		pr_err("%s: 'pre timeout' must be less than 'timeout'!\n",
> +		       __func__);
> +		return -EINVAL;

Already checked by the watchdog core.

> +	}
> +	timeout_fmt = wdev->timeout * 1000 | (WDT_TIMEOUT_ACT << 24);
> +	pretimeout_fmt = pretimeout * 1000 | (WDT_PRETIMEOUT_ACT << 24);
> +	set_buf32(&buf[WDT_TIMEOUT_IDX], le32_to_cpu(timeout_fmt));
> +	set_buf32(&buf[WDT_PRETIMEOUT_IDX], le32_to_cpu(pretimeout_fmt));
> +
> +	ret = nct6694_write_msg(nct6694, REQUEST_WDT_MOD,
> +				REQUEST_WDT_CMD0_OFFSET(data->wdev_idx),
> +				REQUEST_WDT_CMD0_LEN, buf);
> +	if (ret) {
> +		pr_err("%s: Don't write the setup command in Start stage!\n", __func__);

Besides it being noise, I don't even understand what this message is
supposed to mean, and neither would anyone else.

> +		return ret;
> +	}
> +
> +	wdev->pretimeout = pretimeout;
> +	return 0;
> +}
> +
> +static unsigned int nct6694_wdt_get_time(struct watchdog_device *wdev)
> +{
> +	struct nct6694_wdt_data *data = watchdog_get_drvdata(wdev);
> +	struct nct6694 *nct6694 = data->nct6694;
> +	unsigned char buf[WDT_COUNTDOWN_LEN];
> +	unsigned int timeleft_ms;
> +	int ret;
> +
> +	ret = nct6694_read_msg(nct6694, REQUEST_WDT_MOD,
> +			       REQUEST_WDT_CMD0_OFFSET(data->wdev_idx),
> +			       REQUEST_WDT_CMD0_LEN, WDT_COUNTDOWN_IDX,
> +			       WDT_COUNTDOWN_LEN, buf);
> +	if (ret)
> +		pr_err("%s: Failed to get WDT device!\n", __func__);
> +
> +	timeleft_ms = ((buf[2] << 16) | (buf[1] << 8) | buf[0]) & 0xFFFFFF;

If the above command failed this will be a random number.

> +
> +	return timeleft_ms / 1000;
> +}
> +
> +static int nct6694_wdt_setup(struct watchdog_device *wdev)
> +{
> +	struct nct6694_wdt_data *data = watchdog_get_drvdata(wdev);
> +	struct nct6694 *nct6694 = data->nct6694;
> +	unsigned char buf[REQUEST_WDT_CMD0_LEN] = {0};
> +	unsigned int timeout_fmt, pretimeout_fmt;
> +	int ret;
> +
> +	if (timeout)
> +		wdev->timeout = timeout;
> +
Already set.

> +	if (pretimeout) {
> +		wdev->pretimeout = pretimeout;

Pretimeout is already set in the probe function. Do it completely there.

> +		pretimeout_fmt = wdev->pretimeout * 1000 | (WDT_PRETIMEOUT_ACT << 24);
> +	} else {
> +		pretimeout_fmt = 0;
> +	}
> +
> +	timeout_fmt = wdev->timeout * 1000 | (WDT_TIMEOUT_ACT << 24);
> +	set_buf32(&buf[WDT_TIMEOUT_IDX], le32_to_cpu(timeout_fmt));
> +	set_buf32(&buf[WDT_PRETIMEOUT_IDX], le32_to_cpu(pretimeout_fmt));
> +
> +	ret = nct6694_write_msg(nct6694, REQUEST_WDT_MOD,
> +				REQUEST_WDT_CMD0_OFFSET(data->wdev_idx),
> +				REQUEST_WDT_CMD0_LEN, buf);


This seems pretty pointless at this time. Why not do it in the watchdog
start function ?

> +	if (ret)
> +		return ret;
> +
> +	pr_info("Setting WDT(%d): timeout = %d, pretimeout = %d\n",
> +		data->wdev_idx, wdev->timeout, wdev->pretimeout);
> +
> +	return 0;
> +}
> +
> +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 nct6694 *nct6694 = dev_get_drvdata(pdev->dev.parent);
> +	struct nct6694_wdt_data *data;
> +	struct watchdog_device *wdev;
> +	int ret;
> +
> +	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
> +	if (!data)
> +		return -ENOMEM;
> +
> +	data->nct6694 = nct6694;
> +	data->wdev_idx = cell->id;
> +
> +	wdev = &data->wdev;
> +	wdev->info = &nct6694_wdt_info;
> +	wdev->ops = &nct6694_wdt_ops;
> +	wdev->timeout = WATCHDOG_TIMEOUT;
> +	wdev->pretimeout = WATCHDOG_PRETIMEOUT;
> +	wdev->min_timeout = 1;
> +	wdev->max_timeout = 255;
> +
> +	platform_set_drvdata(pdev, data);
> +
> +	/* Register watchdog timer device to WDT framework */
> +	watchdog_set_drvdata(&data->wdev, data);
> +	watchdog_init_timeout(&data->wdev, timeout, &pdev->dev);
> +	watchdog_set_nowayout(&data->wdev, nowayout);
> +	watchdog_stop_on_reboot(&data->wdev);
> +
> +	ret = devm_watchdog_register_device(&pdev->dev, &data->wdev);
> +	if (ret) {
> +		dev_err(&pdev->dev, "%s: Failed to register watchdog device: %d\n",
> +			__func__, ret);
> +		return ret;
> +	}
> +
> +	ret = nct6694_wdt_setup(&data->wdev);

This is too late. It needs to be done before registering the watchdog.

> +	if (ret) {
> +		dev_err(&pdev->dev, "Failed to setup WDT device!\n");
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static struct platform_driver nct6694_wdt_driver = {
> +	.driver = {
> +		.name	= DRVNAME,
> +	},
> +	.probe		= nct6694_wdt_probe,
> +};
> +
> +static int __init nct6694_init(void)
> +{
> +	int err;
> +
> +	err = platform_driver_register(&nct6694_wdt_driver);
> +	if (!err) {
> +		if (err)
> +			platform_driver_unregister(&nct6694_wdt_driver);
> +	}
> +
> +	return err;
> +}
> +subsys_initcall(nct6694_init);
> +
> +static void __exit nct6694_exit(void)
> +{
> +	platform_driver_unregister(&nct6694_wdt_driver);
> +}
> +module_exit(nct6694_exit);
> +
> +MODULE_DESCRIPTION("USB-WDT driver for NCT6694");
> +MODULE_AUTHOR("Ming Yu <tmyu0@...oton.com>");
> +MODULE_LICENSE("GPL");

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