| /* |
| * AMD Elan SC520 processor Watchdog Timer driver for Linux 2.4.x |
| * |
| * Based on acquirewdt.c by Alan Cox, |
| * and sbc60xxwdt.c by Jakob Oestergaard <jakob@ostenfeld.dk> |
| * |
| * This program is free software; you can redistribute it and/or |
| * modify it under the terms of the GNU General Public License |
| * as published by the Free Software Foundation; either version |
| * 2 of the License, or (at your option) any later version. |
| * |
| * The authors do NOT admit liability nor provide warranty for |
| * any of this software. This material is provided "AS-IS" in |
| * the hope that it may be useful for others. |
| * |
| * (c) Copyright 2001 Scott Jennings <linuxdrivers@oro.net> |
| * 9/27 - 2001 [Initial release] |
| * |
| * Additional fixes Alan Cox |
| * - Fixed formatting |
| * - Removed debug printks |
| * - Fixed SMP built kernel deadlock |
| * - Switched to private locks not lock_kernel |
| * - Used ioremap/writew/readw |
| * - Added NOWAYOUT support |
| * |
| * Theory of operation: |
| * A Watchdog Timer (WDT) is a hardware circuit that can |
| * reset the computer system in case of a software fault. |
| * You probably knew that already. |
| * |
| * Usually a userspace daemon will notify the kernel WDT driver |
| * via the /proc/watchdog special device file that userspace is |
| * still alive, at regular intervals. When such a notification |
| * occurs, the driver will usually tell the hardware watchdog |
| * that everything is in order, and that the watchdog should wait |
| * for yet another little while to reset the system. |
| * If userspace fails (RAM error, kernel bug, whatever), the |
| * notifications cease to occur, and the hardware watchdog will |
| * reset the system (causing a reboot) after the timeout occurs. |
| * |
| * This WDT driver is different from most other Linux WDT |
| * drivers in that the driver will ping the watchdog by itself, |
| * because this particular WDT has a very short timeout (1.6 |
| * seconds) and it would be insane to count on any userspace |
| * daemon always getting scheduled within that time frame. |
| * |
| * This driver uses memory mapped IO, and spinlock. |
| */ |
| |
| #include <linux/module.h> |
| #include <linux/version.h> |
| #include <linux/types.h> |
| #include <linux/errno.h> |
| #include <linux/kernel.h> |
| #include <linux/timer.h> |
| #include <linux/sched.h> |
| #include <linux/miscdevice.h> |
| #include <linux/watchdog.h> |
| #include <linux/slab.h> |
| #include <linux/ioport.h> |
| #include <linux/fcntl.h> |
| #include <linux/smp_lock.h> |
| #include <asm/io.h> |
| #include <asm/uaccess.h> |
| #include <asm/system.h> |
| #include <linux/notifier.h> |
| #include <linux/reboot.h> |
| #include <linux/init.h> |
| |
| /* |
| * The SC520 can timeout anywhere from 492us to 32.21s. |
| * If we reset the watchdog every ~250ms we should be safe. |
| */ |
| |
| #define WDT_INTERVAL (HZ/4+1) |
| |
| /* |
| * We must not require too good response from the userspace daemon. |
| * Here we require the userspace daemon to send us a heartbeat |
| * char to /dev/watchdog every 30 seconds. |
| */ |
| |
| #define WDT_HEARTBEAT (HZ * 30) |
| |
| /* |
| * AMD Elan SC520 timeout value is 492us times a power of 2 (0-7) |
| * |
| * 0: 492us 2: 1.01s 4: 4.03s 6: 16.22s |
| * 1: 503ms 3: 2.01s 5: 8.05s 7: 32.21s |
| */ |
| |
| #define TIMEOUT_EXPONENT ( 1 << 3 ) /* 0x08 = 2.01s */ |
| |
| /* #define MMCR_BASE_DEFAULT 0xfffef000 */ |
| #define MMCR_BASE_DEFAULT ((__u16 *)0xffffe) |
| #define OFFS_WDTMRCTL ((unsigned int)0xcb0) |
| #define WDT_ENB 0x8000 /* [15] Watchdog Timer Enable */ |
| #define WDT_WRST_ENB 0x4000 /* [14] Watchdog Timer Reset Enable */ |
| |
| #define OUR_NAME "sc520_wdt" |
| |
| #define WRT_DOG(data) *wdtmrctl=data |
| |
| static __u16 *wdtmrctl; |
| |
| static void wdt_timer_ping(unsigned long); |
| static struct timer_list timer; |
| static unsigned long next_heartbeat; |
| static unsigned long wdt_is_open; |
| static int wdt_expect_close; |
| |
| #ifdef CONFIG_WATCHDOG_NOWAYOUT |
| static int nowayout = 1; |
| #else |
| static int nowayout = 0; |
| #endif |
| |
| MODULE_PARM(nowayout,"i"); |
| MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=CONFIG_WATCHDOG_NOWAYOUT)"); |
| |
| static spinlock_t wdt_spinlock; |
| /* |
| * Whack the dog |
| */ |
| |
| static void wdt_timer_ping(unsigned long data) |
| { |
| /* If we got a heartbeat pulse within the WDT_US_INTERVAL |
| * we agree to ping the WDT |
| */ |
| if(time_before(jiffies, next_heartbeat)) |
| { |
| /* Ping the WDT */ |
| spin_lock(&wdt_spinlock); |
| writew(0xAAAA, wdtmrctl); |
| writew(0x5555, wdtmrctl); |
| spin_unlock(&wdt_spinlock); |
| |
| /* Re-set the timer interval */ |
| timer.expires = jiffies + WDT_INTERVAL; |
| add_timer(&timer); |
| } else { |
| printk(OUR_NAME ": Heartbeat lost! Will not ping the watchdog\n"); |
| } |
| } |
| |
| /* |
| * Utility routines |
| */ |
| |
| static void wdt_config(int writeval) |
| { |
| __u16 dummy; |
| unsigned long flags; |
| |
| /* buy some time (ping) */ |
| spin_lock_irqsave(&wdt_spinlock, flags); |
| dummy=readw(wdtmrctl); /* ensure write synchronization */ |
| writew(0xAAAA, wdtmrctl); |
| writew(0x5555, wdtmrctl); |
| /* make WDT configuration register writable one time */ |
| writew(0x3333, wdtmrctl); |
| writew(0xCCCC, wdtmrctl); |
| /* write WDT configuration register */ |
| writew(writeval, wdtmrctl); |
| spin_unlock_irqrestore(&wdt_spinlock, flags); |
| } |
| |
| static void wdt_startup(void) |
| { |
| next_heartbeat = jiffies + WDT_HEARTBEAT; |
| |
| /* Start the timer */ |
| timer.expires = jiffies + WDT_INTERVAL; |
| add_timer(&timer); |
| |
| wdt_config(WDT_ENB | WDT_WRST_ENB | TIMEOUT_EXPONENT); |
| printk(OUR_NAME ": Watchdog timer is now enabled.\n"); |
| } |
| |
| static void wdt_turnoff(void) |
| { |
| if (!nowayout) { |
| /* Stop the timer */ |
| del_timer(&timer); |
| wdt_config(0); |
| printk(OUR_NAME ": Watchdog timer is now disabled...\n"); |
| } |
| } |
| |
| |
| /* |
| * /dev/watchdog handling |
| */ |
| |
| static ssize_t fop_write(struct file * file, const char * buf, size_t count, loff_t * ppos) |
| { |
| /* We can't seek */ |
| if(ppos != &file->f_pos) |
| return -ESPIPE; |
| |
| /* See if we got the magic character */ |
| if(count) |
| { |
| size_t ofs; |
| |
| /* note: just in case someone wrote the magic character |
| * five months ago... */ |
| wdt_expect_close = 0; |
| |
| /* now scan */ |
| for(ofs = 0; ofs != count; ofs++) { |
| char c; |
| if (get_user(c, buf + ofs)) |
| return -EFAULT; |
| if(c == 'V') |
| wdt_expect_close = 1; |
| } |
| |
| /* Well, anyhow someone wrote to us, we should return that favour */ |
| next_heartbeat = jiffies + WDT_HEARTBEAT; |
| return 1; |
| } |
| return 0; |
| } |
| |
| static int fop_open(struct inode * inode, struct file * file) |
| { |
| switch(MINOR(inode->i_rdev)) |
| { |
| case WATCHDOG_MINOR: |
| /* Just in case we're already talking to someone... */ |
| if(test_and_set_bit(0, &wdt_is_open)) |
| return -EBUSY; |
| /* Good, fire up the show */ |
| wdt_startup(); |
| if (nowayout) { |
| MOD_INC_USE_COUNT; |
| } |
| return 0; |
| default: |
| return -ENODEV; |
| } |
| } |
| |
| static int fop_close(struct inode * inode, struct file * file) |
| { |
| if(MINOR(inode->i_rdev) == WATCHDOG_MINOR) |
| { |
| if(wdt_expect_close) |
| wdt_turnoff(); |
| else { |
| del_timer(&timer); |
| printk(OUR_NAME ": device file closed unexpectedly. Will not stop the WDT!\n"); |
| } |
| } |
| clear_bit(0, &wdt_is_open); |
| return 0; |
| } |
| |
| static long long fop_llseek(struct file *file, long long offset, int origin) |
| { |
| return -ESPIPE; |
| } |
| |
| static int fop_ioctl(struct inode *inode, struct file *file, unsigned int cmd, |
| unsigned long arg) |
| { |
| static struct watchdog_info ident= |
| { |
| WDIOF_MAGICCLOSE, |
| 1, |
| "SC520" |
| }; |
| |
| switch(cmd) |
| { |
| default: |
| return -ENOIOCTLCMD; |
| case WDIOC_GETSUPPORT: |
| return copy_to_user((struct watchdog_info *)arg, &ident, sizeof(ident))?-EFAULT:0; |
| case WDIOC_KEEPALIVE: |
| next_heartbeat = jiffies + WDT_HEARTBEAT; |
| return 0; |
| } |
| } |
| |
| static struct file_operations wdt_fops = { |
| owner: THIS_MODULE, |
| llseek: fop_llseek, |
| write: fop_write, |
| open: fop_open, |
| release: fop_close, |
| ioctl: fop_ioctl |
| }; |
| |
| static struct miscdevice wdt_miscdev = { |
| WATCHDOG_MINOR, |
| "watchdog", |
| &wdt_fops |
| }; |
| |
| /* |
| * Notifier for system down |
| */ |
| |
| static int wdt_notify_sys(struct notifier_block *this, unsigned long code, |
| void *unused) |
| { |
| if(code==SYS_DOWN || code==SYS_HALT) |
| wdt_turnoff(); |
| return NOTIFY_DONE; |
| } |
| |
| /* |
| * The WDT needs to learn about soft shutdowns in order to |
| * turn the timebomb registers off. |
| */ |
| |
| static struct notifier_block wdt_notifier= |
| { |
| wdt_notify_sys, |
| 0, |
| 0 |
| }; |
| |
| static void __exit sc520_wdt_unload(void) |
| { |
| wdt_turnoff(); |
| |
| /* Deregister */ |
| misc_deregister(&wdt_miscdev); |
| iounmap(wdtmrctl); |
| unregister_reboot_notifier(&wdt_notifier); |
| } |
| |
| static int __init sc520_wdt_init(void) |
| { |
| int rc = -EBUSY; |
| unsigned long cbar; |
| |
| spin_lock_init(&wdt_spinlock); |
| |
| init_timer(&timer); |
| timer.function = wdt_timer_ping; |
| timer.data = 0; |
| |
| rc = misc_register(&wdt_miscdev); |
| if (rc) |
| goto err_out_region2; |
| |
| rc = register_reboot_notifier(&wdt_notifier); |
| if (rc) |
| goto err_out_miscdev; |
| |
| /* get the Base Address Register */ |
| cbar = inl_p(0xfffc); |
| printk(OUR_NAME ": CBAR: 0x%08lx\n", cbar); |
| /* check if MMCR aliasing bit is set */ |
| if (cbar & 0x80000000) { |
| printk(OUR_NAME ": MMCR Aliasing enabled.\n"); |
| wdtmrctl = (__u16 *)(cbar & 0x3fffffff); |
| } else { |
| printk(OUR_NAME "!!! WARNING !!!\n" |
| "\t MMCR Aliasing found NOT enabled!\n" |
| "\t Using default value of: %p\n" |
| "\t This has not been tested!\n" |
| "\t Please email Scott Jennings <smj@oro.net>\n" |
| "\t and Bill Jennings <bj@oro.net> if it works!\n" |
| , MMCR_BASE_DEFAULT |
| ); |
| wdtmrctl = MMCR_BASE_DEFAULT; |
| } |
| |
| wdtmrctl = (__u16 *)((char *)wdtmrctl + OFFS_WDTMRCTL); |
| wdtmrctl = ioremap((unsigned long)wdtmrctl, 2); |
| printk(KERN_INFO OUR_NAME ": WDT driver for SC520 initialised.\n"); |
| |
| return 0; |
| |
| err_out_miscdev: |
| misc_deregister(&wdt_miscdev); |
| err_out_region2: |
| return rc; |
| } |
| |
| module_init(sc520_wdt_init); |
| module_exit(sc520_wdt_unload); |
| |
| MODULE_AUTHOR("Scott and Bill Jennings"); |
| MODULE_DESCRIPTION("Driver for watchdog timer in AMD \"Elan\" SC520 uProcessor"); |
| MODULE_LICENSE("GPL"); |
| EXPORT_NO_SYMBOLS; |