| /* |
| * ALi M7101 PMU Computer Watchdog Timer driver for Linux 2.4.x |
| * |
| * Based on w83877f_wdt.c by Scott Jennings <management@oro.net> |
| * and the Cobalt kernel WDT timer driver by Tim Hockin |
| * <thockin@cobaltnet.com> |
| * |
| * (c)2002 Steve Hill <steve@navaho.co.uk> |
| * |
| * 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. |
| */ |
| |
| #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> |
| #include <linux/pci.h> |
| |
| #define OUR_NAME "alim7101_wdt" |
| |
| #define WDT_ENABLE 0x9C |
| #define WDT_DISABLE 0x8C |
| |
| #define ALI_7101_WDT 0x92 |
| #define ALI_WDT_ARM 0x01 |
| |
| /* |
| * We're going to use a 1 second timeout. |
| * 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) |
| |
| 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; |
| static struct pci_dev *alim7101_pmu; |
| |
| #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)"); |
| |
| /* |
| * 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 |
| */ |
| char tmp; |
| |
| if(time_before(jiffies, next_heartbeat)) |
| { |
| /* Ping the WDT (this is actually a disarm/arm sequence) */ |
| pci_read_config_byte(alim7101_pmu, 0x92, &tmp); |
| pci_write_config_byte(alim7101_pmu, ALI_7101_WDT, (tmp & ~ALI_WDT_ARM)); |
| pci_write_config_byte(alim7101_pmu, ALI_7101_WDT, (tmp | ALI_WDT_ARM)); |
| } else { |
| printk(OUR_NAME ": Heartbeat lost! Will not ping the watchdog\n"); |
| } |
| /* Re-set the timer interval */ |
| timer.expires = jiffies + WDT_INTERVAL; |
| add_timer(&timer); |
| } |
| |
| /* |
| * Utility routines |
| */ |
| |
| static void wdt_change(int writeval) |
| { |
| char tmp; |
| |
| pci_read_config_byte(alim7101_pmu, 0x92, &tmp); |
| if (writeval == WDT_ENABLE) |
| pci_write_config_byte(alim7101_pmu, ALI_7101_WDT, (tmp | ALI_WDT_ARM)); |
| else |
| pci_write_config_byte(alim7101_pmu, ALI_7101_WDT, (tmp & ~ALI_WDT_ARM)); |
| } |
| |
| static void wdt_startup(void) |
| { |
| next_heartbeat = jiffies + WDT_HEARTBEAT; |
| |
| /* We must enable before we kick off the timer in case the timer |
| occurs as we ping it */ |
| |
| wdt_change(WDT_ENABLE); |
| |
| /* Start the timer */ |
| timer.expires = jiffies + WDT_INTERVAL; |
| add_timer(&timer); |
| |
| |
| printk(OUR_NAME ": Watchdog timer is now enabled.\n"); |
| } |
| |
| static void wdt_turnoff(void) |
| { |
| /* Stop the timer */ |
| del_timer_sync(&timer); |
| wdt_change(WDT_DISABLE); |
| 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) |
| { |
| 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 = 1; |
| } |
| } |
| |
| /* someone wrote to us, we should restart timer */ |
| next_heartbeat = jiffies + WDT_HEARTBEAT; |
| return 1; |
| }; |
| return 0; |
| } |
| |
| static ssize_t fop_read(struct file * file, char * buf, size_t count, loff_t * ppos) |
| { |
| /* No can do */ |
| return -EINVAL; |
| } |
| |
| 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; |
| /* Good, fire up the show */ |
| wdt_startup(); |
| return 0; |
| } |
| |
| static int fop_close(struct inode * inode, struct file * file) |
| { |
| if ((wdt_expect_close) || (! nowayout)) |
| wdt_turnoff(); |
| else { |
| printk(OUR_NAME ": device file closed unexpectedly. Will not stop the WDT!\n"); |
| } |
| clear_bit(0, &wdt_is_open); |
| return 0; |
| } |
| |
| static int fop_ioctl(struct inode *inode, struct file *file, unsigned int cmd, unsigned long arg) |
| { |
| static struct watchdog_info ident= |
| { |
| WDIOF_MAGICCLOSE, |
| 1, |
| "ALiM7101" |
| }; |
| |
| switch(cmd) |
| { |
| 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; |
| default: |
| return -ENOTTY; |
| } |
| } |
| |
| static struct file_operations wdt_fops = { |
| owner: THIS_MODULE, |
| llseek: no_llseek, |
| read: fop_read, |
| 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(); |
| if (code==SYS_RESTART) { |
| /* |
| * Cobalt devices have no way of rebooting themselves other than |
| * getting the watchdog to pull reset, so we restart the watchdog on |
| * reboot with no heartbeat |
| */ |
| wdt_change(WDT_ENABLE); |
| printk(OUR_NAME ": Watchdog timer is now enabled with no heartbeat - should reboot in ~1 second.\n"); |
| }; |
| 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 alim7101_wdt_unload(void) |
| { |
| wdt_turnoff(); |
| /* Deregister */ |
| misc_deregister(&wdt_miscdev); |
| unregister_reboot_notifier(&wdt_notifier); |
| } |
| |
| static int __init alim7101_wdt_init(void) |
| { |
| int rc = -EBUSY; |
| struct pci_dev *ali1543_south; |
| char tmp; |
| |
| printk(KERN_INFO OUR_NAME ": Steve Hill <steve@navaho.co.uk>.\n"); |
| alim7101_pmu = pci_find_device(PCI_VENDOR_ID_AL, PCI_DEVICE_ID_AL_M7101,NULL); |
| if (!alim7101_pmu) { |
| printk(KERN_INFO OUR_NAME ": ALi M7101 PMU not present - WDT not set\n"); |
| return -EBUSY; |
| }; |
| |
| /* Set the WDT in the PMU to 1 second */ |
| pci_write_config_byte(alim7101_pmu, ALI_7101_WDT, 0x02); |
| |
| ali1543_south = pci_find_device(PCI_VENDOR_ID_AL, PCI_DEVICE_ID_AL_M1533, NULL); |
| if (!ali1543_south) { |
| printk(KERN_INFO OUR_NAME ": ALi 1543 South-Bridge not present - WDT not set\n"); |
| return -EBUSY; |
| }; |
| pci_read_config_byte(ali1543_south, 0x5e, &tmp); |
| if ((tmp & 0x1e) != 0x12) { |
| printk(KERN_INFO OUR_NAME ": ALi 1543 South-Bridge does not have the correct revision number (???1001?) - WDT not set\n"); |
| return -EBUSY; |
| }; |
| |
| init_timer(&timer); |
| timer.function = wdt_timer_ping; |
| timer.data = 1; |
| |
| rc = misc_register(&wdt_miscdev); |
| if (rc) |
| return rc; |
| |
| rc = register_reboot_notifier(&wdt_notifier); |
| if (rc) { |
| misc_deregister(&wdt_miscdev); |
| return rc; |
| }; |
| |
| printk(KERN_INFO OUR_NAME ": WDT driver for ALi M7101 initialised.\n"); |
| return 0; |
| } |
| |
| module_init(alim7101_wdt_init); |
| module_exit(alim7101_wdt_unload); |
| |
| EXPORT_NO_SYMBOLS; |
| MODULE_AUTHOR("Steve Hill"); |
| MODULE_LICENSE("GPL"); |