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384 lines
9.9 KiB
384 lines
9.9 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
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/* |
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* 60xx Single Board Computer Watchdog Timer driver for Linux 2.2.x |
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* |
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* Based on acquirewdt.c by Alan Cox. |
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* |
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* The author does NOT admit liability nor provide warranty for |
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* any of this software. This material is provided "AS-IS" in |
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* the hope that it may be useful for others. |
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* |
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* (c) Copyright 2000 Jakob Oestergaard <[email protected]> |
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* |
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* 12/4 - 2000 [Initial revision] |
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* 25/4 - 2000 Added /dev/watchdog support |
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* 09/5 - 2001 [[email protected]] fixed fop_write to "return 1" |
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* on success |
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* 12/4 - 2002 [[email protected]] eliminate fop_read |
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* fix possible wdt_is_open race |
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* add CONFIG_WATCHDOG_NOWAYOUT support |
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* remove lock_kernel/unlock_kernel pairs |
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* added KERN_* to printk's |
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* got rid of extraneous comments |
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* changed watchdog_info to correctly reflect what |
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* the driver offers |
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* added WDIOC_GETSTATUS, WDIOC_GETBOOTSTATUS, |
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* WDIOC_SETTIMEOUT, WDIOC_GETTIMEOUT, and |
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* WDIOC_SETOPTIONS ioctls |
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* 09/8 - 2003 [[email protected]] cleanup of trailing spaces |
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* use module_param |
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* made timeout (the emulated heartbeat) a |
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* module_param |
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* made the keepalive ping an internal subroutine |
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* made wdt_stop and wdt_start module params |
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* added extra printk's for startup problems |
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* added MODULE_AUTHOR and MODULE_DESCRIPTION info |
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* |
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* This WDT driver is different from the other Linux WDT |
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* drivers in the following ways: |
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* *) The driver will ping the watchdog by itself, because this |
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* particular WDT has a very short timeout (one second) and it |
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* would be insane to count on any userspace daemon always |
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* getting scheduled within that time frame. |
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*/ |
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
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#include <linux/module.h> |
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#include <linux/moduleparam.h> |
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#include <linux/types.h> |
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#include <linux/timer.h> |
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#include <linux/jiffies.h> |
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#include <linux/miscdevice.h> |
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#include <linux/watchdog.h> |
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#include <linux/fs.h> |
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#include <linux/ioport.h> |
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#include <linux/notifier.h> |
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#include <linux/reboot.h> |
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#include <linux/init.h> |
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#include <linux/io.h> |
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#include <linux/uaccess.h> |
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#define OUR_NAME "sbc60xxwdt" |
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#define PFX OUR_NAME ": " |
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/* |
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* You must set these - The driver cannot probe for the settings |
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*/ |
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static int wdt_stop = 0x45; |
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module_param(wdt_stop, int, 0); |
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MODULE_PARM_DESC(wdt_stop, "SBC60xx WDT 'stop' io port (default 0x45)"); |
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static int wdt_start = 0x443; |
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module_param(wdt_start, int, 0); |
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MODULE_PARM_DESC(wdt_start, "SBC60xx WDT 'start' io port (default 0x443)"); |
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/* |
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* The 60xx board can use watchdog timeout values from one second |
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* to several minutes. The default is one second, so if we reset |
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* the watchdog every ~250ms we should be safe. |
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*/ |
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#define WDT_INTERVAL (HZ/4+1) |
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/* |
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* We must not require too good response from the userspace daemon. |
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* Here we require the userspace daemon to send us a heartbeat |
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* char to /dev/watchdog every 30 seconds. |
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* If the daemon pulses us every 25 seconds, we can still afford |
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* a 5 second scheduling delay on the (high priority) daemon. That |
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* should be sufficient for a box under any load. |
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*/ |
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#define WATCHDOG_TIMEOUT 30 /* 30 sec default timeout */ |
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static int timeout = WATCHDOG_TIMEOUT; /* in seconds, multiplied by HZ to |
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get seconds to wait for a ping */ |
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module_param(timeout, int, 0); |
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MODULE_PARM_DESC(timeout, |
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"Watchdog timeout in seconds. (1<=timeout<=3600, default=" |
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__MODULE_STRING(WATCHDOG_TIMEOUT) ")"); |
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static bool nowayout = WATCHDOG_NOWAYOUT; |
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module_param(nowayout, bool, 0); |
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MODULE_PARM_DESC(nowayout, |
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"Watchdog cannot be stopped once started (default=" |
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__MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); |
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static void wdt_timer_ping(struct timer_list *); |
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static DEFINE_TIMER(timer, wdt_timer_ping); |
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static unsigned long next_heartbeat; |
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static unsigned long wdt_is_open; |
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static char wdt_expect_close; |
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/* |
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* Whack the dog |
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*/ |
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static void wdt_timer_ping(struct timer_list *unused) |
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{ |
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/* If we got a heartbeat pulse within the WDT_US_INTERVAL |
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* we agree to ping the WDT |
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*/ |
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if (time_before(jiffies, next_heartbeat)) { |
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/* Ping the WDT by reading from wdt_start */ |
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inb_p(wdt_start); |
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/* Re-set the timer interval */ |
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mod_timer(&timer, jiffies + WDT_INTERVAL); |
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} else |
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pr_warn("Heartbeat lost! Will not ping the watchdog\n"); |
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} |
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/* |
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* Utility routines |
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*/ |
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static void wdt_startup(void) |
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{ |
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next_heartbeat = jiffies + (timeout * HZ); |
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/* Start the timer */ |
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mod_timer(&timer, jiffies + WDT_INTERVAL); |
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pr_info("Watchdog timer is now enabled\n"); |
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} |
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static void wdt_turnoff(void) |
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{ |
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/* Stop the timer */ |
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del_timer_sync(&timer); |
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inb_p(wdt_stop); |
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pr_info("Watchdog timer is now disabled...\n"); |
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} |
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static void wdt_keepalive(void) |
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{ |
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/* user land ping */ |
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next_heartbeat = jiffies + (timeout * HZ); |
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} |
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/* |
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* /dev/watchdog handling |
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*/ |
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static ssize_t fop_write(struct file *file, const char __user *buf, |
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size_t count, 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 (count) { |
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if (!nowayout) { |
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size_t ofs; |
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/* note: just in case someone wrote the |
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magic character five months ago... */ |
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wdt_expect_close = 0; |
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/* scan to see whether or not we got the |
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magic character */ |
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for (ofs = 0; ofs != count; ofs++) { |
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char c; |
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if (get_user(c, buf + ofs)) |
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return -EFAULT; |
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if (c == 'V') |
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wdt_expect_close = 42; |
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} |
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} |
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/* Well, anyhow someone wrote to us, we should |
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return that favour */ |
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wdt_keepalive(); |
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} |
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return count; |
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} |
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static int fop_open(struct inode *inode, struct file *file) |
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{ |
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/* Just in case we're already talking to someone... */ |
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if (test_and_set_bit(0, &wdt_is_open)) |
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return -EBUSY; |
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if (nowayout) |
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__module_get(THIS_MODULE); |
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/* Good, fire up the show */ |
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wdt_startup(); |
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return stream_open(inode, file); |
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} |
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static int fop_close(struct inode *inode, struct file *file) |
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{ |
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if (wdt_expect_close == 42) |
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wdt_turnoff(); |
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else { |
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del_timer(&timer); |
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pr_crit("device file closed unexpectedly. Will not stop the WDT!\n"); |
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} |
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clear_bit(0, &wdt_is_open); |
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wdt_expect_close = 0; |
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return 0; |
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} |
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static long fop_ioctl(struct file *file, 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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static const struct watchdog_info ident = { |
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.options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | |
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WDIOF_MAGICCLOSE, |
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.firmware_version = 1, |
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.identity = "SBC60xx", |
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}; |
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switch (cmd) { |
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case WDIOC_GETSUPPORT: |
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return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0; |
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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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{ |
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int new_options, retval = -EINVAL; |
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if (get_user(new_options, p)) |
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return -EFAULT; |
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if (new_options & WDIOS_DISABLECARD) { |
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wdt_turnoff(); |
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retval = 0; |
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} |
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if (new_options & WDIOS_ENABLECARD) { |
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wdt_startup(); |
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retval = 0; |
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} |
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return retval; |
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} |
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case WDIOC_KEEPALIVE: |
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wdt_keepalive(); |
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return 0; |
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case WDIOC_SETTIMEOUT: |
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{ |
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int new_timeout; |
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if (get_user(new_timeout, p)) |
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return -EFAULT; |
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/* arbitrary upper limit */ |
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if (new_timeout < 1 || new_timeout > 3600) |
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return -EINVAL; |
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timeout = new_timeout; |
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wdt_keepalive(); |
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} |
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fallthrough; |
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case WDIOC_GETTIMEOUT: |
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return put_user(timeout, p); |
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default: |
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return -ENOTTY; |
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} |
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} |
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static const struct file_operations wdt_fops = { |
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.owner = THIS_MODULE, |
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.llseek = no_llseek, |
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.write = fop_write, |
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.open = fop_open, |
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.release = fop_close, |
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.unlocked_ioctl = fop_ioctl, |
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.compat_ioctl = compat_ptr_ioctl, |
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}; |
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static struct miscdevice wdt_miscdev = { |
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.minor = WATCHDOG_MINOR, |
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.name = "watchdog", |
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.fops = &wdt_fops, |
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}; |
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/* |
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* Notifier for system down |
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*/ |
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static int wdt_notify_sys(struct notifier_block *this, unsigned long code, |
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void *unused) |
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{ |
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if (code == SYS_DOWN || code == SYS_HALT) |
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wdt_turnoff(); |
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return NOTIFY_DONE; |
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} |
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/* |
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* The WDT needs to learn about soft shutdowns in order to |
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* turn the timebomb registers off. |
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*/ |
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static struct notifier_block wdt_notifier = { |
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.notifier_call = wdt_notify_sys, |
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}; |
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static void __exit sbc60xxwdt_unload(void) |
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{ |
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wdt_turnoff(); |
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/* Deregister */ |
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misc_deregister(&wdt_miscdev); |
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unregister_reboot_notifier(&wdt_notifier); |
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if ((wdt_stop != 0x45) && (wdt_stop != wdt_start)) |
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release_region(wdt_stop, 1); |
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release_region(wdt_start, 1); |
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} |
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static int __init sbc60xxwdt_init(void) |
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{ |
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int rc = -EBUSY; |
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if (timeout < 1 || timeout > 3600) { /* arbitrary upper limit */ |
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timeout = WATCHDOG_TIMEOUT; |
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pr_info("timeout value must be 1 <= x <= 3600, using %d\n", |
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timeout); |
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} |
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if (!request_region(wdt_start, 1, "SBC 60XX WDT")) { |
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pr_err("I/O address 0x%04x already in use\n", wdt_start); |
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rc = -EIO; |
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goto err_out; |
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} |
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/* We cannot reserve 0x45 - the kernel already has! */ |
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if (wdt_stop != 0x45 && wdt_stop != wdt_start) { |
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if (!request_region(wdt_stop, 1, "SBC 60XX WDT")) { |
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pr_err("I/O address 0x%04x already in use\n", wdt_stop); |
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rc = -EIO; |
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goto err_out_region1; |
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} |
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} |
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rc = register_reboot_notifier(&wdt_notifier); |
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if (rc) { |
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pr_err("cannot register reboot notifier (err=%d)\n", rc); |
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goto err_out_region2; |
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} |
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rc = misc_register(&wdt_miscdev); |
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if (rc) { |
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pr_err("cannot register miscdev on minor=%d (err=%d)\n", |
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wdt_miscdev.minor, rc); |
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goto err_out_reboot; |
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} |
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pr_info("WDT driver for 60XX single board computer initialised. timeout=%d sec (nowayout=%d)\n", |
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timeout, nowayout); |
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return 0; |
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err_out_reboot: |
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unregister_reboot_notifier(&wdt_notifier); |
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err_out_region2: |
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if (wdt_stop != 0x45 && wdt_stop != wdt_start) |
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release_region(wdt_stop, 1); |
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err_out_region1: |
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release_region(wdt_start, 1); |
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err_out: |
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return rc; |
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} |
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module_init(sbc60xxwdt_init); |
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module_exit(sbc60xxwdt_unload); |
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MODULE_AUTHOR("Jakob Oestergaard <[email protected]>"); |
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MODULE_DESCRIPTION("60xx Single Board Computer Watchdog Timer driver"); |
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MODULE_LICENSE("GPL");
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