/* * AMD Elan SC520 processor Watchdog Timer driver * * Based on acquirewdt.c by Alan Cox, * and sbc60xxwdt.c by Jakob Oestergaard * * 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 * 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 * * 4/12 - 2002 Changes by Rob Radez * - Change comments * - Eliminate fop_llseek * - Change CONFIG_WATCHDOG_NOWAYOUT semantics * - Add KERN_* tags to printks * - fix possible wdt_is_open race * - Report proper capabilities in watchdog_info * - Add WDIOC_{GETSTATUS, GETBOOTSTATUS, SETTIMEOUT, * GETTIMEOUT, SETOPTIONS} ioctls * 09/8 - 2003 Changes by Wim Van Sebroeck * - cleanup of trailing spaces * - added extra printk's for startup problems * - use module_param * - made timeout (the emulated heartbeat) a module_param * - made the keepalive ping an internal subroutine * * 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 #include #include #include #include #include #include #include #include #include #include #include #include #include /* * 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 WATCHDOG_TIMEOUT 30 /* 30 sec default timeout */ static int timeout = WATCHDOG_TIMEOUT; /* in seconds, will be multiplied by HZ to get seconds to wait for a ping */ module_param(timeout, int, 0); MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds. (1<=timeout<=3600, default=" __MODULE_STRING(WATCHDOG_TIMEOUT) ")"); /* * 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 PFX OUR_NAME ": " #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 char wdt_expect_close; static spinlock_t wdt_spinlock; #ifdef CONFIG_WATCHDOG_NOWAYOUT static int nowayout = 1; #else static int nowayout = 0; #endif module_param(nowayout, int, 0); MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=CONFIG_WATCHDOG_NOWAYOUT)"); /* * 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(KERN_WARNING PFX "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 + (timeout * HZ); /* Start the timer */ timer.expires = jiffies + WDT_INTERVAL; add_timer(&timer); wdt_config(WDT_ENB | WDT_WRST_ENB | TIMEOUT_EXPONENT); printk(KERN_INFO PFX "Watchdog timer is now enabled.\n"); } static void wdt_turnoff(void) { if (!nowayout) { /* Stop the timer */ del_timer(&timer); wdt_config(0); printk(KERN_INFO PFX "Watchdog timer is now disabled...\n"); } } static void wdt_keepalive(void) { /* user land ping */ next_heartbeat = jiffies + (timeout * HZ); } /* * /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 'V' and reload the timer */ if(count) { if (!nowayout) { 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 = 42; } } /* Well, anyhow someone wrote to us, we should return that favour */ wdt_keepalive(); } return count; } static int fop_open(struct inode * inode, struct file * file) { /* Just in case we're already talking to someone... */ if(test_and_set_bit(0, &wdt_is_open)) return -EBUSY; if (nowayout) __module_get(THIS_MODULE); /* Good, fire up the show */ wdt_startup(); return 0; } static int fop_close(struct inode * inode, struct file * file) { if(wdt_expect_close == 42) wdt_turnoff(); else { del_timer(&timer); printk(KERN_CRIT PFX "device file closed unexpectedly. Will not stop the WDT!\n"); } clear_bit(0, &wdt_is_open); wdt_expect_close = 0; return 0; } static int fop_ioctl(struct inode *inode, struct file *file, unsigned int cmd, unsigned long arg) { static struct watchdog_info ident= { .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE, .firmware_version = 1, .identity = "SC520", }; switch(cmd) { default: return -ENOIOCTLCMD; case WDIOC_GETSUPPORT: return copy_to_user((struct watchdog_info *)arg, &ident, sizeof(ident))?-EFAULT:0; case WDIOC_GETSTATUS: case WDIOC_GETBOOTSTATUS: return put_user(0, (int *)arg); case WDIOC_KEEPALIVE: wdt_keepalive(); return 0; case WDIOC_SETOPTIONS: { int new_options, retval = -EINVAL; if(get_user(new_options, (int *)arg)) return -EFAULT; if(new_options & WDIOS_DISABLECARD) { wdt_turnoff(); retval = 0; } if(new_options & WDIOS_ENABLECARD) { wdt_startup(); retval = 0; } return retval; } case WDIOC_SETTIMEOUT: { int new_timeout; if(get_user(new_timeout, (int *)arg)) return -EFAULT; if(new_timeout < 1 || new_timeout > 3600) /* arbitrary upper limit */ return -EINVAL; timeout = new_timeout; wdt_keepalive(); /* Fall through */ } case WDIOC_GETTIMEOUT: return put_user(timeout, (int *)arg); } } static struct file_operations wdt_fops = { .owner = THIS_MODULE, .llseek = no_llseek, .write = fop_write, .open = fop_open, .release = fop_close, .ioctl = fop_ioctl, }; static struct miscdevice wdt_miscdev = { .minor = WATCHDOG_MINOR, .name = "watchdog", .fops = &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= { .notifier_call = wdt_notify_sys, }; 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); if(timeout < 1 || timeout > 3600) /* arbitrary upper limit */ { timeout = WATCHDOG_TIMEOUT; printk(KERN_INFO PFX "timeout value must be 1<=x<=3600, using %d\n", timeout); } init_timer(&timer); timer.function = wdt_timer_ping; timer.data = 0; rc = misc_register(&wdt_miscdev); if (rc) { printk(KERN_ERR PFX "cannot register miscdev on minor=%d (err=%d)\n", wdt_miscdev.minor, rc); goto err_out_region2; } rc = register_reboot_notifier(&wdt_notifier); if (rc) { printk(KERN_ERR PFX "cannot register reboot notifier (err=%d)\n", rc); goto err_out_miscdev; } /* get the Base Address Register */ cbar = inl_p(0xfffc); printk(KERN_INFO PFX "CBAR: 0x%08lx\n", cbar); /* check if MMCR aliasing bit is set */ if (cbar & 0x80000000) { printk(KERN_INFO PFX "MMCR Aliasing enabled.\n"); wdtmrctl = (__u16 *)(cbar & 0x3fffffff); } else { printk(KERN_INFO PFX "!!! 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 \n" "\t and Bill Jennings if it works!\n" , MMCR_BASE_DEFAULT ); wdtmrctl = MMCR_BASE_DEFAULT; } wdtmrctl = (__u16 *)((char *)wdtmrctl + OFFS_WDTMRCTL); wdtmrctl = ioremap((unsigned long)wdtmrctl, 2); if (!wdtmrctl) { printk (KERN_ERR PFX "Unable to remap memory.\n"); rc = -ENOMEM; goto err_out_notifier; } printk(KERN_INFO PFX "WDT driver for SC520 initialised. timeout=%d sec (nowayout=%d)\n", timeout,nowayout); return 0; err_out_notifier: unregister_reboot_notifier(&wdt_notifier); 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"); MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);