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

Guenter Roeck
2024-11-21T14:15:16Z

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");