Dear Guenter,

Thank you for your comments,
I will remove the unnecessary logs in the next patch.

Guenter Roeck [off-list ref] 於 2024年10月24日 週四 下午11:33寫道：

On 10/24/24 01:59, Ming Yu wrote:

quoted

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 | 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.

[Ming] Okay! I will change it.

quoted

+
+     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.

quoted

+
+     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.

[Ming] Excuse me, is any recommendation about pretimeout value?

quoted

+     }
+
+     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.

[Ming] I understand. I will remove it.

quoted

+     }
+     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.

quoted

+             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.

[Ming] Okay! I will update error handling about return value.

quoted

+
+     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.

quoted

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

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

quoted

+             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 ?

[Ming] Yes, I will remove it and do it in the start callback in the next patch.

quoted

+     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.

quoted

+     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 [off-list ref]");
+MODULE_LICENSE("GPL");

Best regards,
Ming