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+/*
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+ * Watchdog driver for Atmel AT32AP700X devices
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+ *
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+ * Copyright (C) 2005-2006 Atmel Corporation
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+ *
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+ * This program is free software; you can redistribute it and/or modify
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+ * it under the terms of the GNU General Public License version 2 as
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+ * published by the Free Software Foundation.
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+ */
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+
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+#include <linux/init.h>
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+#include <linux/kernel.h>
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+#include <linux/module.h>
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+#include <linux/moduleparam.h>
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+#include <linux/miscdevice.h>
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+#include <linux/fs.h>
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+#include <linux/platform_device.h>
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+#include <linux/watchdog.h>
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+#include <linux/uaccess.h>
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+#include <linux/io.h>
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+#include <linux/spinlock.h>
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+
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+#define TIMEOUT_MIN 1
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+#define TIMEOUT_MAX 2
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+#define TIMEOUT_DEFAULT TIMEOUT_MAX
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+
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+/* module parameters */
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+static int timeout = TIMEOUT_DEFAULT;
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+module_param(timeout, int, 0);
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+MODULE_PARM_DESC(timeout,
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+ "Timeout value. Limited to be 1 or 2 seconds. (default="
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+ __MODULE_STRING(TIMEOUT_DEFAULT) ")");
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+
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+static int nowayout = WATCHDOG_NOWAYOUT;
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+module_param(nowayout, int, 0);
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+MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
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+ __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
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+
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+/* Watchdog registers and write/read macro */
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+#define WDT_CTRL 0x00
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+#define WDT_CTRL_EN 0
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+#define WDT_CTRL_PSEL 8
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+#define WDT_CTRL_KEY 24
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+
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+#define WDT_CLR 0x04
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+
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+#define WDT_BIT(name) (1 << WDT_##name)
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+#define WDT_BF(name, value) ((value) << WDT_##name)
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+
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+#define wdt_readl(dev, reg) \
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+ __raw_readl((dev)->regs + WDT_##reg)
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+#define wdt_writel(dev, reg, value) \
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+ __raw_writel((value), (dev)->regs + WDT_##reg)
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+
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+struct wdt_at32ap700x {
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+ void __iomem *regs;
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+ spinlock_t io_lock;
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+ int timeout;
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+ unsigned long users;
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+ struct miscdevice miscdev;
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+};
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+
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+static struct wdt_at32ap700x *wdt;
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+static char expect_release;
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+
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+/*
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+ * Disable the watchdog.
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+ */
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+static inline void at32_wdt_stop(void)
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+{
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+ unsigned long psel;
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+
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+ spin_lock(&wdt->io_lock);
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+ psel = wdt_readl(wdt, CTRL) & WDT_BF(CTRL_PSEL, 0x0f);
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+ wdt_writel(wdt, CTRL, psel | WDT_BF(CTRL_KEY, 0x55));
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+ wdt_writel(wdt, CTRL, psel | WDT_BF(CTRL_KEY, 0xaa));
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+ spin_unlock(&wdt->io_lock);
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+}
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+
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+/*
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+ * Enable and reset the watchdog.
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+ */
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+static inline void at32_wdt_start(void)
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+{
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+ /* 0xf is 2^16 divider = 2 sec, 0xe is 2^15 divider = 1 sec */
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+ unsigned long psel = (wdt->timeout > 1) ? 0xf : 0xe;
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+
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+ spin_lock(&wdt->io_lock);
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+ wdt_writel(wdt, CTRL, WDT_BIT(CTRL_EN)
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+ | WDT_BF(CTRL_PSEL, psel)
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+ | WDT_BF(CTRL_KEY, 0x55));
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+ wdt_writel(wdt, CTRL, WDT_BIT(CTRL_EN)
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+ | WDT_BF(CTRL_PSEL, psel)
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+ | WDT_BF(CTRL_KEY, 0xaa));
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+ spin_unlock(&wdt->io_lock);
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+}
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+
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+/*
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+ * Pat the watchdog timer.
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+ */
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+static inline void at32_wdt_pat(void)
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+{
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+ spin_lock(&wdt->io_lock);
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+ wdt_writel(wdt, CLR, 0x42);
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+ spin_unlock(&wdt->io_lock);
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+}
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+
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+/*
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+ * Watchdog device is opened, and watchdog starts running.
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+ */
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+static int at32_wdt_open(struct inode *inode, struct file *file)
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+{
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+ if (test_and_set_bit(1, &wdt->users))
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+ return -EBUSY;
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+
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+ at32_wdt_start();
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+ return nonseekable_open(inode, file);
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+}
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+
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+/*
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+ * Close the watchdog device.
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+ */
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+static int at32_wdt_close(struct inode *inode, struct file *file)
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+{
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+ if (expect_release == 42) {
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+ at32_wdt_stop();
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+ } else {
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+ dev_dbg(wdt->miscdev.parent,
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+ "Unexpected close, not stopping watchdog!\n");
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+ at32_wdt_pat();
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+ }
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+ clear_bit(1, &wdt->users);
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+ expect_release = 0;
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+ return 0;
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+}
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+
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+/*
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+ * Change the watchdog time interval.
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+ */
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+static int at32_wdt_settimeout(int time)
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+{
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+ /*
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+ * All counting occurs at 1 / SLOW_CLOCK (32 kHz) and max prescaler is
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+ * 2 ^ 16 allowing up to 2 seconds timeout.
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+ */
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+ if ((time < TIMEOUT_MIN) || (time > TIMEOUT_MAX))
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+ return -EINVAL;
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+
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+ /*
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+ * Set new watchdog time. It will be used when at32_wdt_start() is
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+ * called.
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+ */
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+ wdt->timeout = time;
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+ return 0;
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+}
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+
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+static struct watchdog_info at32_wdt_info = {
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+ .identity = "at32ap700x watchdog",
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+ .options = WDIOF_SETTIMEOUT |
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+ WDIOF_KEEPALIVEPING |
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+ WDIOF_MAGICCLOSE,
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+};
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+
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+/*
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+ * Handle commands from user-space.
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+ */
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+static int at32_wdt_ioctl(struct inode *inode, struct file *file,
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+ unsigned int cmd, unsigned long arg)
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+{
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+ int ret = -ENOTTY;
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+ int time;
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+ void __user *argp = (void __user *)arg;
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+ int __user *p = argp;
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+
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+ switch (cmd) {
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+ case WDIOC_KEEPALIVE:
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+ at32_wdt_pat();
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+ ret = 0;
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+ break;
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+ case WDIOC_GETSUPPORT:
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+ ret = copy_to_user(argp, &at32_wdt_info,
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+ sizeof(at32_wdt_info)) ? -EFAULT : 0;
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+ break;
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+ case WDIOC_SETTIMEOUT:
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+ ret = get_user(time, p);
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+ if (ret)
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+ break;
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+ ret = at32_wdt_settimeout(time);
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+ if (ret)
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+ break;
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+ /* Enable new time value */
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+ at32_wdt_start();
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+ /* fall through */
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+ case WDIOC_GETTIMEOUT:
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+ ret = put_user(wdt->timeout, p);
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+ break;
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+ case WDIOC_GETSTATUS: /* fall through */
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+ case WDIOC_GETBOOTSTATUS:
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+ ret = put_user(0, p);
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+ break;
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+ case WDIOC_SETOPTIONS:
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+ ret = get_user(time, p);
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+ if (ret)
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+ break;
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+ if (time & WDIOS_DISABLECARD)
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+ at32_wdt_stop();
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+ if (time & WDIOS_ENABLECARD)
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+ at32_wdt_start();
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+ ret = 0;
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+ break;
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+ }
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+
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+ return ret;
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+}
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+
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+static ssize_t at32_wdt_write(struct file *file, const char __user *data,
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+ size_t len, loff_t *ppos)
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+{
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+ /* See if we got the magic character 'V' and reload the timer */
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+ if (len) {
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+ if (!nowayout) {
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+ size_t i;
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+
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+ /*
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+ * note: just in case someone wrote the magic
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+ * character five months ago...
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+ */
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+ expect_release = 0;
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+
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+ /*
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+ * scan to see whether or not we got the magic
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+ * character
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+ */
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+ for (i = 0; i != len; i++) {
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+ char c;
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+ if (get_user(c, data+i))
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+ return -EFAULT;
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+ if (c == 'V')
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+ expect_release = 42;
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+ }
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+ }
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+ /* someone wrote to us, we should pat the watchdog */
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+ at32_wdt_pat();
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+ }
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+ return len;
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+}
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+
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+static const struct file_operations at32_wdt_fops = {
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+ .owner = THIS_MODULE,
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+ .llseek = no_llseek,
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+ .ioctl = at32_wdt_ioctl,
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+ .open = at32_wdt_open,
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+ .release = at32_wdt_close,
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+ .write = at32_wdt_write,
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+};
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+
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+static int __init at32_wdt_probe(struct platform_device *pdev)
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+{
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+ struct resource *regs;
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+ int ret;
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+
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+ if (wdt) {
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+ dev_dbg(&pdev->dev, "only 1 wdt instance supported.\n");
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+ return -EBUSY;
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+ }
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+
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+ regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
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+ if (!regs) {
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+ dev_dbg(&pdev->dev, "missing mmio resource\n");
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+ return -ENXIO;
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+ }
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+
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+ wdt = kzalloc(sizeof(struct wdt_at32ap700x), GFP_KERNEL);
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+ if (!wdt) {
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+ dev_dbg(&pdev->dev, "no memory for wdt structure\n");
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+ return -ENOMEM;
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+ }
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+
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+ wdt->regs = ioremap(regs->start, regs->end - regs->start + 1);
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+ if (!wdt->regs) {
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+ ret = -ENOMEM;
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+ dev_dbg(&pdev->dev, "could not map I/O memory\n");
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+ goto err_free;
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+ }
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+ spin_lock_init(&wdt->io_lock);
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+ wdt->users = 0;
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+ wdt->miscdev.minor = WATCHDOG_MINOR;
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+ wdt->miscdev.name = "watchdog";
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+ wdt->miscdev.fops = &at32_wdt_fops;
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+
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+ if (at32_wdt_settimeout(timeout)) {
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+ at32_wdt_settimeout(TIMEOUT_DEFAULT);
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+ dev_dbg(&pdev->dev,
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+ "default timeout invalid, set to %d sec.\n",
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+ TIMEOUT_DEFAULT);
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+ }
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+
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+ ret = misc_register(&wdt->miscdev);
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+ if (ret) {
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+ dev_dbg(&pdev->dev, "failed to register wdt miscdev\n");
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+ goto err_iounmap;
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+ }
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+
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+ platform_set_drvdata(pdev, wdt);
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+ wdt->miscdev.parent = &pdev->dev;
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+ dev_info(&pdev->dev,
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+ "AT32AP700X WDT at 0x%p, timeout %d sec (nowayout=%d)\n",
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+ wdt->regs, wdt->timeout, nowayout);
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+
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+ return 0;
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+
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+err_iounmap:
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+ iounmap(wdt->regs);
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+err_free:
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+ kfree(wdt);
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+ wdt = NULL;
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+ return ret;
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+}
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+
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+static int __exit at32_wdt_remove(struct platform_device *pdev)
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+{
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+ if (wdt && platform_get_drvdata(pdev) == wdt) {
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+ /* Stop the timer before we leave */
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+ if (!nowayout)
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+ at32_wdt_stop();
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+
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+ misc_deregister(&wdt->miscdev);
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+ iounmap(wdt->regs);
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+ kfree(wdt);
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+ wdt = NULL;
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+ platform_set_drvdata(pdev, NULL);
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+ }
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+
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+ return 0;
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+}
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+
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+static void at32_wdt_shutdown(struct platform_device *pdev)
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+{
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+ at32_wdt_stop();
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+}
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+
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+#ifdef CONFIG_PM
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+static int at32_wdt_suspend(struct platform_device *pdev, pm_message_t message)
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+{
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+ at32_wdt_stop();
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+ return 0;
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+}
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+
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+static int at32_wdt_resume(struct platform_device *pdev)
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+{
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+ if (wdt->users)
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+ at32_wdt_start();
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+ return 0;
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+}
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+#else
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+#define at32_wdt_suspend NULL
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+#define at32_wdt_resume NULL
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+#endif
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+
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+static struct platform_driver at32_wdt_driver = {
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+ .remove = __exit_p(at32_wdt_remove),
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+ .suspend = at32_wdt_suspend,
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+ .resume = at32_wdt_resume,
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+ .driver = {
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+ .name = "at32_wdt",
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+ .owner = THIS_MODULE,
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+ },
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+ .shutdown = at32_wdt_shutdown,
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+};
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+
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+static int __init at32_wdt_init(void)
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+{
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+ return platform_driver_probe(&at32_wdt_driver, at32_wdt_probe);
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+}
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+module_init(at32_wdt_init);
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+
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+static void __exit at32_wdt_exit(void)
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+{
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+ platform_driver_unregister(&at32_wdt_driver);
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+}
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+module_exit(at32_wdt_exit);
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+
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+MODULE_AUTHOR("Hans-Christian Egtvedt <hcegtvedt@atmel.com>");
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+MODULE_DESCRIPTION("Watchdog driver for Atmel AT32AP700X");
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+MODULE_LICENSE("GPL");
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+MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
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