Date:   Wed, 1 Jul 2020 10:09:48 +0000
From:   Johnson CH Chen (陳昭勳) 
        <JohnsonCH.Chen@...a.com>
To:     "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>,
        Guenter Roeck <linux@...ck-us.net>
Subject: [PATCH] rtc: ds1374: wdt: Use watchdog core for watchdog part

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.
  */
 /*
  * 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).
+	 */
 	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
+#define TIMER_MARGIN_MIN	1
+#define TIMER_MARGIN_MAX	(60*60*24) /* one day */
 
 #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)");
+
+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)
 {
-	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;
 
 	/* 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);
 }
 
-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 = {
+	.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);
+	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");
+	watchdog_unregister_device(&ds1374->wdt);
 #endif
 
 	if (client->irq > 0) {
-- 
2.20.1

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