/* * drivers/watchdog/ar7_wdt.c * * Copyright (C) 2007 Nicolas Thill * Copyright (c) 2005 Enrik Berkhan * * Some code taken from: * National Semiconductor SCx200 Watchdog support * Copyright (c) 2001,2002 Christer Weinigel * * 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. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #define DRVNAME "ar7_wdt" #define LONGNAME "TI AR7 Watchdog Timer" MODULE_AUTHOR("Nicolas Thill "); MODULE_DESCRIPTION(LONGNAME); MODULE_LICENSE("GPL"); MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); static int margin = 60; module_param(margin, int, 0); MODULE_PARM_DESC(margin, "Watchdog margin in seconds"); static int nowayout = WATCHDOG_NOWAYOUT; module_param(nowayout, int, 0); MODULE_PARM_DESC(nowayout, "Disable watchdog shutdown on close"); #define READ_REG(x) readl((void __iomem *)&(x)) #define WRITE_REG(x, v) writel((v), (void __iomem *)&(x)) struct ar7_wdt { u32 kick_lock; u32 kick; u32 change_lock; u32 change; u32 disable_lock; u32 disable; u32 prescale_lock; u32 prescale; }; static struct semaphore open_semaphore; static unsigned expect_close; /* XXX currently fixed, allows max margin ~68.72 secs */ #define prescale_value 0xffff /* Offset of the WDT registers */ static unsigned long ar7_regs_wdt; /* Pointer to the remapped WDT IO space */ static struct ar7_wdt *ar7_wdt; static void ar7_wdt_get_regs(void) { u16 chip_id = ar7_chip_id(); switch (chip_id) { case AR7_CHIP_7100: case AR7_CHIP_7200: ar7_regs_wdt = AR7_REGS_WDT; break; default: ar7_regs_wdt = UR8_REGS_WDT; break; } } static void ar7_wdt_kick(u32 value) { WRITE_REG(ar7_wdt->kick_lock, 0x5555); if ((READ_REG(ar7_wdt->kick_lock) & 3) == 1) { WRITE_REG(ar7_wdt->kick_lock, 0xaaaa); if ((READ_REG(ar7_wdt->kick_lock) & 3) == 3) { WRITE_REG(ar7_wdt->kick, value); return; } } printk(KERN_ERR DRVNAME ": failed to unlock WDT kick reg\n"); } static void ar7_wdt_prescale(u32 value) { WRITE_REG(ar7_wdt->prescale_lock, 0x5a5a); if ((READ_REG(ar7_wdt->prescale_lock) & 3) == 1) { WRITE_REG(ar7_wdt->prescale_lock, 0xa5a5); if ((READ_REG(ar7_wdt->prescale_lock) & 3) == 3) { WRITE_REG(ar7_wdt->prescale, value); return; } } printk(KERN_ERR DRVNAME ": failed to unlock WDT prescale reg\n"); } static void ar7_wdt_change(u32 value) { WRITE_REG(ar7_wdt->change_lock, 0x6666); if ((READ_REG(ar7_wdt->change_lock) & 3) == 1) { WRITE_REG(ar7_wdt->change_lock, 0xbbbb); if ((READ_REG(ar7_wdt->change_lock) & 3) == 3) { WRITE_REG(ar7_wdt->change, value); return; } } printk(KERN_ERR DRVNAME ": failed to unlock WDT change reg\n"); } static void ar7_wdt_disable(u32 value) { WRITE_REG(ar7_wdt->disable_lock, 0x7777); if ((READ_REG(ar7_wdt->disable_lock) & 3) == 1) { WRITE_REG(ar7_wdt->disable_lock, 0xcccc); if ((READ_REG(ar7_wdt->disable_lock) & 3) == 2) { WRITE_REG(ar7_wdt->disable_lock, 0xdddd); if ((READ_REG(ar7_wdt->disable_lock) & 3) == 3) { WRITE_REG(ar7_wdt->disable, value); return; } } } printk(KERN_ERR DRVNAME ": failed to unlock WDT disable reg\n"); } static void ar7_wdt_update_margin(int new_margin) { u32 change; change = new_margin * (ar7_vbus_freq() / prescale_value); if (change < 1) change = 1; if (change > 0xffff) change = 0xffff; ar7_wdt_change(change); margin = change * prescale_value / ar7_vbus_freq(); printk(KERN_INFO DRVNAME ": timer margin %d seconds (prescale %d, change %d, freq %d)\n", margin, prescale_value, change, ar7_vbus_freq()); } static void ar7_wdt_enable_wdt(void) { printk(KERN_DEBUG DRVNAME ": enabling watchdog timer\n"); ar7_wdt_disable(1); ar7_wdt_kick(1); } static void ar7_wdt_disable_wdt(void) { printk(KERN_DEBUG DRVNAME ": disabling watchdog timer\n"); ar7_wdt_disable(0); } static int ar7_wdt_open(struct inode *inode, struct file *file) { /* only allow one at a time */ if (down_trylock(&open_semaphore)) return -EBUSY; ar7_wdt_enable_wdt(); expect_close = 0; return nonseekable_open(inode, file); } static int ar7_wdt_release(struct inode *inode, struct file *file) { if (!expect_close) printk(KERN_WARNING DRVNAME ": watchdog device closed unexpectedly," "will not disable the watchdog timer\n"); else if (!nowayout) ar7_wdt_disable_wdt(); up(&open_semaphore); return 0; } static int ar7_wdt_notify_sys(struct notifier_block *this, unsigned long code, void *unused) { if (code == SYS_HALT || code == SYS_POWER_OFF) if (!nowayout) ar7_wdt_disable_wdt(); return NOTIFY_DONE; } static struct notifier_block ar7_wdt_notifier = { .notifier_call = ar7_wdt_notify_sys }; static ssize_t ar7_wdt_write(struct file *file, const char *data, size_t len, loff_t *ppos) { /* check for a magic close character */ if (len) { size_t i; ar7_wdt_kick(1); expect_close = 0; for (i = 0; i < len; ++i) { char c; if (get_user(c, data+i)) return -EFAULT; if (c == 'V') expect_close = 1; } } return len; } static int ar7_wdt_ioctl(struct inode *inode, struct file *file, unsigned int cmd, unsigned long arg) { static struct watchdog_info ident = { .identity = LONGNAME, .firmware_version = 1, .options = (WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING), }; int new_margin; switch (cmd) { default: return -ENOTTY; case WDIOC_GETSUPPORT: if (copy_to_user((struct watchdog_info *)arg, &ident, sizeof(ident))) return -EFAULT; return 0; case WDIOC_GETSTATUS: case WDIOC_GETBOOTSTATUS: if (put_user(0, (int *)arg)) return -EFAULT; return 0; case WDIOC_KEEPALIVE: ar7_wdt_kick(1); return 0; case WDIOC_SETTIMEOUT: if (get_user(new_margin, (int *)arg)) return -EFAULT; if (new_margin < 1) return -EINVAL; ar7_wdt_update_margin(new_margin); ar7_wdt_kick(1); case WDIOC_GETTIMEOUT: if (put_user(margin, (int *)arg)) return -EFAULT; return 0; } } static const struct file_operations ar7_wdt_fops = { .owner = THIS_MODULE, .write = ar7_wdt_write, .ioctl = ar7_wdt_ioctl, .open = ar7_wdt_open, .release = ar7_wdt_release, }; static struct miscdevice ar7_wdt_miscdev = { .minor = WATCHDOG_MINOR, .name = "watchdog", .fops = &ar7_wdt_fops, }; static int __init ar7_wdt_init(void) { int rc; ar7_wdt_get_regs(); if (!request_mem_region(ar7_regs_wdt, sizeof(struct ar7_wdt), LONGNAME)) { printk(KERN_WARNING DRVNAME ": watchdog I/O region busy\n"); return -EBUSY; } ar7_wdt = (struct ar7_wdt *) ioremap(ar7_regs_wdt, sizeof(struct ar7_wdt)); ar7_wdt_disable_wdt(); ar7_wdt_prescale(prescale_value); ar7_wdt_update_margin(margin); sema_init(&open_semaphore, 1); rc = register_reboot_notifier(&ar7_wdt_notifier); if (rc) { printk(KERN_ERR DRVNAME ": unable to register reboot notifier\n"); goto out_alloc; } rc = misc_register(&ar7_wdt_miscdev); if (rc) { printk(KERN_ERR DRVNAME ": unable to register misc device\n"); goto out_register; } goto out; out_register: unregister_reboot_notifier(&ar7_wdt_notifier); out_alloc: iounmap(ar7_wdt); release_mem_region(ar7_regs_wdt, sizeof(struct ar7_wdt)); out: return rc; } static void __exit ar7_wdt_cleanup(void) { misc_deregister(&ar7_wdt_miscdev); unregister_reboot_notifier(&ar7_wdt_notifier); iounmap(ar7_wdt); release_mem_region(ar7_regs_wdt, sizeof(struct ar7_wdt)); } module_init(ar7_wdt_init); module_exit(ar7_wdt_cleanup);