62322d2554
Mark the static struct file_operations in drivers/char as const. Making them const prevents accidental bugs, and moves them to the .rodata section so that they no longer do any false sharing; in addition with the proper debug option they are then protected against corruption.. [akpm@osdl.org: build fix] Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
288 lines
6.4 KiB
C
288 lines
6.4 KiB
C
/*
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* Watchdog driver for Atmel AT91RM9200 (Thunder)
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*
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* Copyright (C) 2003 SAN People (Pty) Ltd
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#include <linux/errno.h>
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#include <linux/fs.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/miscdevice.h>
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#include <linux/module.h>
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#include <linux/moduleparam.h>
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#include <linux/platform_device.h>
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#include <linux/types.h>
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#include <linux/watchdog.h>
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#include <asm/bitops.h>
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#include <asm/uaccess.h>
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#define WDT_DEFAULT_TIME 5 /* seconds */
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#define WDT_MAX_TIME 256 /* seconds */
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static int wdt_time = WDT_DEFAULT_TIME;
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static int nowayout = WATCHDOG_NOWAYOUT;
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module_param(wdt_time, int, 0);
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MODULE_PARM_DESC(wdt_time, "Watchdog time in seconds. (default="__MODULE_STRING(WDT_DEFAULT_TIME) ")");
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#ifdef CONFIG_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=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
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#endif
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static unsigned long at91wdt_busy;
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/* ......................................................................... */
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/*
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* Disable the watchdog.
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*/
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static void inline at91_wdt_stop(void)
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{
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at91_sys_write(AT91_ST_WDMR, AT91_ST_EXTEN);
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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 void inline at91_wdt_start(void)
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{
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at91_sys_write(AT91_ST_WDMR, AT91_ST_EXTEN | AT91_ST_RSTEN | (((65536 * wdt_time) >> 8) & AT91_ST_WDV));
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at91_sys_write(AT91_ST_CR, AT91_ST_WDRST);
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}
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/*
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* Reload the watchdog timer. (ie, pat the watchdog)
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*/
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static void inline at91_wdt_reload(void)
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{
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at91_sys_write(AT91_ST_CR, AT91_ST_WDRST);
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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 at91_wdt_open(struct inode *inode, struct file *file)
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{
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if (test_and_set_bit(0, &at91wdt_busy))
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return -EBUSY;
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at91_wdt_start();
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return nonseekable_open(inode, file);
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}
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/*
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* Close the watchdog device.
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* If CONFIG_WATCHDOG_NOWAYOUT is NOT defined then the watchdog is also
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* disabled.
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*/
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static int at91_wdt_close(struct inode *inode, struct file *file)
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{
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if (!nowayout)
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at91_wdt_stop(); /* Disable the watchdog when file is closed */
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clear_bit(0, &at91wdt_busy);
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return 0;
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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 at91_wdt_settimeout(int new_time)
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{
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/*
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* All counting occurs at SLOW_CLOCK / 128 = 0.256 Hz
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*
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* Since WDV is a 16-bit counter, the maximum period is
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* 65536 / 0.256 = 256 seconds.
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*/
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if ((new_time <= 0) || (new_time > WDT_MAX_TIME))
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return -EINVAL;
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/* Set new watchdog time. It will be used when at91_wdt_start() is called. */
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wdt_time = new_time;
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return 0;
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}
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static struct watchdog_info at91_wdt_info = {
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.identity = "at91 watchdog",
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.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
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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 at91_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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void __user *argp = (void __user *)arg;
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int __user *p = argp;
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int new_value;
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switch(cmd) {
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case WDIOC_KEEPALIVE:
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at91_wdt_reload(); /* pat the watchdog */
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return 0;
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case WDIOC_GETSUPPORT:
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return copy_to_user(argp, &at91_wdt_info, sizeof(at91_wdt_info)) ? -EFAULT : 0;
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case WDIOC_SETTIMEOUT:
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if (get_user(new_value, p))
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return -EFAULT;
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if (at91_wdt_settimeout(new_value))
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return -EINVAL;
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/* Enable new time value */
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at91_wdt_start();
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/* Return current value */
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return put_user(wdt_time, p);
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case WDIOC_GETTIMEOUT:
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return put_user(wdt_time, p);
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case WDIOC_GETSTATUS:
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case WDIOC_GETBOOTSTATUS:
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return put_user(0, p);
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case WDIOC_SETOPTIONS:
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if (get_user(new_value, p))
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return -EFAULT;
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if (new_value & WDIOS_DISABLECARD)
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at91_wdt_stop();
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if (new_value & WDIOS_ENABLECARD)
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at91_wdt_start();
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return 0;
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default:
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return -ENOIOCTLCMD;
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}
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}
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/*
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* Pat the watchdog whenever device is written to.
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*/
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static ssize_t at91_wdt_write(struct file *file, const char *data, size_t len, loff_t *ppos)
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{
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at91_wdt_reload(); /* pat the watchdog */
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return len;
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}
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/* ......................................................................... */
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static const struct file_operations at91wdt_fops = {
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.owner = THIS_MODULE,
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.llseek = no_llseek,
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.ioctl = at91_wdt_ioctl,
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.open = at91_wdt_open,
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.release = at91_wdt_close,
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.write = at91_wdt_write,
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};
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static struct miscdevice at91wdt_miscdev = {
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.minor = WATCHDOG_MINOR,
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.name = "watchdog",
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.fops = &at91wdt_fops,
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};
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static int __init at91wdt_probe(struct platform_device *pdev)
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{
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int res;
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if (at91wdt_miscdev.dev)
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return -EBUSY;
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at91wdt_miscdev.dev = &pdev->dev;
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res = misc_register(&at91wdt_miscdev);
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if (res)
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return res;
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printk("AT91 Watchdog Timer enabled (%d seconds%s)\n", wdt_time, nowayout ? ", nowayout" : "");
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return 0;
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}
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static int __exit at91wdt_remove(struct platform_device *pdev)
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{
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int res;
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res = misc_deregister(&at91wdt_miscdev);
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if (!res)
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at91wdt_miscdev.dev = NULL;
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return res;
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}
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static void at91wdt_shutdown(struct platform_device *pdev)
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{
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at91_wdt_stop();
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}
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#ifdef CONFIG_PM
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static int at91wdt_suspend(struct platform_device *pdev, pm_message_t message)
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{
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at91_wdt_stop();
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return 0;
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}
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static int at91wdt_resume(struct platform_device *pdev)
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{
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if (at91wdt_busy)
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at91_wdt_start();
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return 0;
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}
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#else
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#define at91wdt_suspend NULL
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#define at91wdt_resume NULL
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#endif
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static struct platform_driver at91wdt_driver = {
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.probe = at91wdt_probe,
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.remove = __exit_p(at91wdt_remove),
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.shutdown = at91wdt_shutdown,
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.suspend = at91wdt_suspend,
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.resume = at91wdt_resume,
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.driver = {
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.name = "at91_wdt",
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.owner = THIS_MODULE,
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},
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};
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static int __init at91_wdt_init(void)
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{
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/* Check that the heartbeat value is within range; if not reset to the default */
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if (at91_wdt_settimeout(wdt_time)) {
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at91_wdt_settimeout(WDT_DEFAULT_TIME);
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pr_info("at91_wdt: wdt_time value must be 1 <= wdt_time <= 256, using %d\n", wdt_time);
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}
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return platform_driver_register(&at91wdt_driver);
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}
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static void __exit at91_wdt_exit(void)
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{
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platform_driver_unregister(&at91wdt_driver);
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}
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module_init(at91_wdt_init);
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module_exit(at91_wdt_exit);
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MODULE_AUTHOR("Andrew Victor");
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MODULE_DESCRIPTION("Watchdog driver for Atmel AT91RM9200");
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MODULE_LICENSE("GPL");
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MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
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