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Message-ID: <cde71ac3-2747-cb8e-6a25-15a3e182da4a@roeck-us.net>
Date: Wed, 1 Jul 2020 07:05:36 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: Johnson CH Chen (陳昭勳)
<JohnsonCH.Chen@...a.com>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Cc: "linux-rtc@...r.kernel.org" <linux-rtc@...r.kernel.org>,
LINUX-WATCHDOG <linux-watchdog@...r.kernel.org>,
Wim Van Sebroeck <wim@...ux-watchdog.org>,
Alessandro Zummo <a.zummo@...ertech.it>,
Alexandre Belloni <alexandre.belloni@...tlin.com>
Subject: Re: [PATCH] rtc: ds1374: wdt: Use watchdog core for watchdog part
On 7/1/20 3:09 AM, Johnson CH Chen (陳昭勳) wrote:
> Let ds1374 watchdog use watchdog core. It also includes
> improving watchdog timer setting and nowayout, and just uses ioctl()
> of watchdog core.
>
> Signed-off-by: Johnson Chen <johnsonch.chen@...a.com>
> ---
> drivers/rtc/rtc-ds1374.c | 257 ++++++++++-----------------------------
> 1 file changed, 67 insertions(+), 190 deletions(-)
>
> diff --git a/drivers/rtc/rtc-ds1374.c b/drivers/rtc/rtc-ds1374.c
> index 9c51a12cf70f..25b28f7546ff 100644
> --- a/drivers/rtc/rtc-ds1374.c
> +++ b/drivers/rtc/rtc-ds1374.c
> @@ -1,3 +1,4 @@
> +// SPDX-License-Identifier: GPL-2.0
> /*
> * RTC client/driver for the Maxim/Dallas DS1374 Real-Time Clock over I2C
> *
> @@ -6,11 +7,7 @@
> *
> * Copyright (C) 2014 Rose Technology
> * Copyright (C) 2006-2007 Freescale Semiconductor
> - *
> - * 2005 (c) MontaVista Software, Inc. This file is licensed under
> - * the terms of the GNU General Public License version 2. This program
> - * is licensed "as is" without any warranty of any kind, whether express
> - * or implied.
> + * Copyright (C) 2005 (c) MontaVista Software, Inc.
> */
The above should be a separate patch.
> /*
> * It would be more efficient to use i2c msgs/i2c_transfer directly but, as
> @@ -46,6 +43,7 @@
> #define DS1374_REG_WDALM2 0x06
> #define DS1374_REG_CR 0x07 /* Control */
> #define DS1374_REG_CR_AIE 0x01 /* Alarm Int. Enable */
> +#define DS1374_REG_CR_WDSTR 0x08 /* 1=INT, 0=RST */
> #define DS1374_REG_CR_WDALM 0x20 /* 1=Watchdog, 0=Alarm */
> #define DS1374_REG_CR_WACE 0x40 /* WD/Alarm counter enable */
> #define DS1374_REG_SR 0x08 /* Status */
> @@ -71,7 +69,9 @@ struct ds1374 {
> struct i2c_client *client;
> struct rtc_device *rtc;
> struct work_struct work;
> -
> +#ifdef CONFIG_RTC_DRV_DS1374_WDT
> + struct watchdog_device wdt;
> +#endif
> /* The mutex protects alarm operations, and prevents a race
> * between the enable_irq() in the workqueue and the free_irq()
> * in the remove function.
> @@ -257,7 +257,8 @@ static int ds1374_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
> goto out;
>
> /* Disable any existing alarm before setting the new one
> - * (or lack thereof). */
> + * (or lack thereof).
> + */
Unrelated (and cosmetic). Drop or separate patch.
> cr &= ~DS1374_REG_CR_WACE;
>
> ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr);
> @@ -371,14 +372,21 @@ static const struct rtc_class_ops ds1374_rtc_ops = {
> */
> static struct i2c_client *save_client;
> /* Default margin */
> -#define WD_TIMO 131762
> +#define TIMER_MARGIN_DEFAULT 32
Parameter alignment is off. Please use tab after TIMER_MARGIN_DEFAULT.
> +#define TIMER_MARGIN_MIN 1
> +#define TIMER_MARGIN_MAX (60*60*24) /* one day */
Real limits are necessary. The old limit was 16777216/4096 = 4096 seconds.
Ok, time to look up the datasheet. The counter is a 24-bit value.
The maximum value is thus 0xffffff, or 16777215. 16777215 / 4096 = 4095,
which should be the maximum timeout in seconds to set here.
>
> #define DRV_NAME "DS1374 Watchdog"
>
> -static int wdt_margin = WD_TIMO;
> -static unsigned long wdt_is_open;
> -module_param(wdt_margin, int, 0);
> -MODULE_PARM_DESC(wdt_margin, "Watchdog timeout in seconds (default 32s)");
> +static int timeout = TIMER_MARGIN_DEFAULT;
> +module_param(timeout, int, 0);
> +MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds (default 32s)");
This changes the module parameter which may be unexpected.
I would suggest to keep using wdt_margin.
> +
> +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)")");
> +
>
> static const struct watchdog_info ds1374_wdt_info = {
> .identity = "DS1374 WTD",
> @@ -386,57 +394,61 @@ static const struct watchdog_info ds1374_wdt_info = {
> WDIOF_MAGICCLOSE,
> };
>
> -static int ds1374_wdt_settimeout(unsigned int timeout)
> +static int ds1374_wdt_settimeout(struct watchdog_device *wdt,
> + unsigned int timeout)
This fits into one line (new line length limit)
> {
> - int ret = -ENOIOCTLCMD;
> - int cr;
> + int ret, cr;
> +
> + wdt->timeout = timeout;
>
> - ret = cr = i2c_smbus_read_byte_data(save_client, DS1374_REG_CR);
> + cr = i2c_smbus_read_byte_data(save_client, DS1374_REG_CR);
> + ret = cr;
> if (ret < 0)
> - goto out;
> + return ret;
>
Assignment to ret is pointless. Just return cr if negative.
> /* Disable any existing watchdog/alarm before setting the new one */
> cr &= ~DS1374_REG_CR_WACE;
>
> ret = i2c_smbus_write_byte_data(save_client, DS1374_REG_CR, cr);
> if (ret < 0)
> - goto out;
> + return ret;
>
> /* Set new watchdog time */
> + timeout = timeout * 4096;
> ret = ds1374_write_rtc(save_client, timeout, DS1374_REG_WDALM0, 3);
> if (ret) {
> pr_info("couldn't set new watchdog time\n");
> - goto out;
> + return ret;
> }
>
> /* Enable watchdog timer */
> cr |= DS1374_REG_CR_WACE | DS1374_REG_CR_WDALM;
> + cr &= ~DS1374_REG_CR_WDSTR;/* for RST PIN */
> cr &= ~DS1374_REG_CR_AIE;
>
> ret = i2c_smbus_write_byte_data(save_client, DS1374_REG_CR, cr);
> if (ret < 0)
> - goto out;
> + return ret;
>
> return 0;
> -out:
> - return ret;
> }
>
> -
> /*
> * Reload the watchdog timer. (ie, pat the watchdog)
> */
> -static void ds1374_wdt_ping(void)
> +static int ds1374_wdt_ping(struct watchdog_device *wdt)
> {
> u32 val;
> - int ret = 0;
>
> - ret = ds1374_read_rtc(save_client, &val, DS1374_REG_WDALM0, 3);
> - if (ret)
> - pr_info("WD TICK FAIL!!!!!!!!!! %i\n", ret);
> + return ds1374_read_rtc(save_client, &val, DS1374_REG_WDALM0, 3);
> +}
> +
> +static int ds1374_wdt_start(struct watchdog_device *wdt)
> +{
> + return ds1374_wdt_ping(wdt);
Unnecessary. Just declare the start function and drop the ping function.
See Documentation/watchdog/watchdog-kernel-api.rst
> }
>
> -static void ds1374_wdt_disable(void)
> +static int ds1374_wdt_stop(struct watchdog_device *wdt)
> {
> int cr;
>
> @@ -444,162 +456,17 @@ static void ds1374_wdt_disable(void)
> /* Disable watchdog timer */
> cr &= ~DS1374_REG_CR_WACE;
>
> - i2c_smbus_write_byte_data(save_client, DS1374_REG_CR, cr);
> + return i2c_smbus_write_byte_data(save_client, DS1374_REG_CR, cr);
> }
>
> -/*
> - * Watchdog device is opened, and watchdog starts running.
> - */
> -static int ds1374_wdt_open(struct inode *inode, struct file *file)
> -{
> - struct ds1374 *ds1374 = i2c_get_clientdata(save_client);
> -
> - if (MINOR(inode->i_rdev) == WATCHDOG_MINOR) {
> - mutex_lock(&ds1374->mutex);
> - if (test_and_set_bit(0, &wdt_is_open)) {
> - mutex_unlock(&ds1374->mutex);
> - return -EBUSY;
> - }
> - /*
> - * Activate
> - */
> - wdt_is_open = 1;
> - mutex_unlock(&ds1374->mutex);
> - return stream_open(inode, file);
> - }
> - return -ENODEV;
> -}
> -
> -/*
> - * Close the watchdog device.
> - */
> -static int ds1374_wdt_release(struct inode *inode, struct file *file)
> -{
> - if (MINOR(inode->i_rdev) == WATCHDOG_MINOR)
> - clear_bit(0, &wdt_is_open);
> -
> - return 0;
> -}
> -
> -/*
> - * Pat the watchdog whenever device is written to.
> - */
> -static ssize_t ds1374_wdt_write(struct file *file, const char __user *data,
> - size_t len, loff_t *ppos)
> -{
> - if (len) {
> - ds1374_wdt_ping();
> - return 1;
> - }
> - return 0;
> -}
> -
> -static ssize_t ds1374_wdt_read(struct file *file, char __user *data,
> - size_t len, loff_t *ppos)
> -{
> - return 0;
> -}
> -
> -/*
> - * Handle commands from user-space.
> - */
> -static long ds1374_wdt_ioctl(struct file *file, unsigned int cmd,
> - unsigned long arg)
> -{
> - int new_margin, options;
> -
> - switch (cmd) {
> - case WDIOC_GETSUPPORT:
> - return copy_to_user((struct watchdog_info __user *)arg,
> - &ds1374_wdt_info, sizeof(ds1374_wdt_info)) ? -EFAULT : 0;
> -
> - case WDIOC_GETSTATUS:
> - case WDIOC_GETBOOTSTATUS:
> - return put_user(0, (int __user *)arg);
> - case WDIOC_KEEPALIVE:
> - ds1374_wdt_ping();
> - return 0;
> - case WDIOC_SETTIMEOUT:
> - if (get_user(new_margin, (int __user *)arg))
> - return -EFAULT;
> -
> - /* the hardware's tick rate is 4096 Hz, so
> - * the counter value needs to be scaled accordingly
> - */
> - new_margin <<= 12;
> - if (new_margin < 1 || new_margin > 16777216)
> - return -EINVAL;
> -
> - wdt_margin = new_margin;
> - ds1374_wdt_settimeout(new_margin);
> - ds1374_wdt_ping();
> - /* fallthrough */
> - case WDIOC_GETTIMEOUT:
> - /* when returning ... inverse is true */
> - return put_user((wdt_margin >> 12), (int __user *)arg);
> - case WDIOC_SETOPTIONS:
> - if (copy_from_user(&options, (int __user *)arg, sizeof(int)))
> - return -EFAULT;
> -
> - if (options & WDIOS_DISABLECARD) {
> - pr_info("disable watchdog\n");
> - ds1374_wdt_disable();
> - return 0;
> - }
> -
> - if (options & WDIOS_ENABLECARD) {
> - pr_info("enable watchdog\n");
> - ds1374_wdt_settimeout(wdt_margin);
> - ds1374_wdt_ping();
> - return 0;
> - }
> - return -EINVAL;
> - }
> - return -ENOTTY;
> -}
> -
> -static long ds1374_wdt_unlocked_ioctl(struct file *file, unsigned int cmd,
> - unsigned long arg)
> -{
> - int ret;
> - struct ds1374 *ds1374 = i2c_get_clientdata(save_client);
> -
> - mutex_lock(&ds1374->mutex);
> - ret = ds1374_wdt_ioctl(file, cmd, arg);
> - mutex_unlock(&ds1374->mutex);
> -
> - return ret;
> -}
> -
> -static int ds1374_wdt_notify_sys(struct notifier_block *this,
> - unsigned long code, void *unused)
> -{
> - if (code == SYS_DOWN || code == SYS_HALT)
> - /* Disable Watchdog */
> - ds1374_wdt_disable();
> - return NOTIFY_DONE;
> -}
> -
> -static const struct file_operations ds1374_wdt_fops = {
> - .owner = THIS_MODULE,
> - .read = ds1374_wdt_read,
> - .unlocked_ioctl = ds1374_wdt_unlocked_ioctl,
> - .compat_ioctl = compat_ptr_ioctl,
> - .write = ds1374_wdt_write,
> - .open = ds1374_wdt_open,
> - .release = ds1374_wdt_release,
> - .llseek = no_llseek,
> -};
> -
> -static struct miscdevice ds1374_miscdev = {
> - .minor = WATCHDOG_MINOR,
> - .name = "watchdog",
> - .fops = &ds1374_wdt_fops,
> +static const struct watchdog_ops ds1374_wdt_fops = {
s/fops/ops/
Those are not file operations.
> + .owner = THIS_MODULE,
> + .start = ds1374_wdt_start,
> + .stop = ds1374_wdt_stop,
> + .ping = ds1374_wdt_ping,
> + .set_timeout = ds1374_wdt_settimeout,
> };
>
> -static struct notifier_block ds1374_wdt_notifier = {
> - .notifier_call = ds1374_wdt_notify_sys,
> -};
>
> #endif /*CONFIG_RTC_DRV_DS1374_WDT*/
> /*
> @@ -653,15 +520,25 @@ static int ds1374_probe(struct i2c_client *client,
>
> #ifdef CONFIG_RTC_DRV_DS1374_WDT
> save_client = client;
> - ret = misc_register(&ds1374_miscdev);
> - if (ret)
> - return ret;
> - ret = register_reboot_notifier(&ds1374_wdt_notifier);
> + ds1374->wdt.info = &ds1374_wdt_info;
> + ds1374->wdt.ops = &ds1374_wdt_fops;
> + ds1374->wdt.timeout = TIMER_MARGIN_DEFAULT;
> + ds1374->wdt.min_timeout = TIMER_MARGIN_MIN;
> + ds1374->wdt.max_timeout = TIMER_MARGIN_MAX;
> +
> + watchdog_init_timeout(&ds1374->wdt, timeout, &client->dev);
> + watchdog_set_nowayout(&ds1374->wdt, nowayout);
> + watchdog_stop_on_reboot(&ds1374->wdt);
> + watchdog_stop_on_unregister(&ds1374->wdt);
> +
> + ret = devm_watchdog_register_device(&client->dev, &ds1374->wdt);
> if (ret) {
> - misc_deregister(&ds1374_miscdev);
> + dev_err(&client->dev, "failed to register DS1374 watchdog device\n");
> return ret;
> }
> - ds1374_wdt_settimeout(131072);
> +
> + ds1374_wdt_settimeout(&ds1374->wdt, timeout);
You'll want to do that before registering the watchdog to avoid a
race condition.
> + dev_info(&client->dev, "DS1374 watchdog device enabled\n");
> #endif
>
> return 0;
> @@ -670,10 +547,10 @@ static int ds1374_probe(struct i2c_client *client,
> static int ds1374_remove(struct i2c_client *client)
> {
> struct ds1374 *ds1374 = i2c_get_clientdata(client);
> +
> #ifdef CONFIG_RTC_DRV_DS1374_WDT
> - misc_deregister(&ds1374_miscdev);
> - ds1374_miscdev.parent = NULL;
> - unregister_reboot_notifier(&ds1374_wdt_notifier);
> + dev_warn(&client->dev, "Unregister DS1374 watchdog device\n");
Noise.
> + watchdog_unregister_device(&ds1374->wdt);
Drop: The watchdog was registered using devm_watchdog_register_device().
> #endif
>
> if (client->irq > 0) {
>
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