/* * Watchdog timer for PowerPC Book-E systems * * Author: Matthew McClintock * Maintainer: Kumar Gala * * Copyright 2005, 2008, 2010 Freescale Semiconductor Inc. * * 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. */ #include #include #include #include #include #include #include #include #include #include #include /* If the kernel parameter wdt=1, the watchdog will be enabled at boot. * Also, the wdt_period sets the watchdog timer period timeout. * For E500 cpus the wdt_period sets which bit changing from 0->1 will * trigger a watchog timeout. This watchdog timeout will occur 3 times, the * first time nothing will happen, the second time a watchdog exception will * occur, and the final time the board will reset. */ u32 booke_wdt_enabled; u32 booke_wdt_period = CONFIG_BOOKE_WDT_DEFAULT_TIMEOUT; #ifdef CONFIG_FSL_BOOKE #define WDTP(x) ((((x)&0x3)<<30)|(((x)&0x3c)<<15)) #define WDTP_MASK (WDTP(0x3f)) #else #define WDTP(x) (TCR_WP(x)) #define WDTP_MASK (TCR_WP_MASK) #endif static DEFINE_SPINLOCK(booke_wdt_lock); /* For the specified period, determine the number of seconds * corresponding to the reset time. There will be a watchdog * exception at approximately 3/5 of this time. * * The formula to calculate this is given by: * 2.5 * (2^(63-period+1)) / timebase_freq * * In order to simplify things, we assume that period is * at least 1. This will still result in a very long timeout. */ static unsigned long long period_to_sec(unsigned int period) { unsigned long long tmp = 1ULL << (64 - period); unsigned long tmp2 = ppc_tb_freq; /* tmp may be a very large number and we don't want to overflow, * so divide the timebase freq instead of multiplying tmp */ tmp2 = tmp2 / 5 * 2; do_div(tmp, tmp2); return tmp; } /* * This procedure will find the highest period which will give a timeout * greater than the one required. e.g. for a bus speed of 66666666 and * and a parameter of 2 secs, then this procedure will return a value of 38. */ static unsigned int sec_to_period(unsigned int secs) { unsigned int period; for (period = 63; period > 0; period--) { if (period_to_sec(period) >= secs) return period; } return 0; } static void __booke_wdt_set(void *data) { u32 val; val = mfspr(SPRN_TCR); val &= ~WDTP_MASK; val |= WDTP(booke_wdt_period); mtspr(SPRN_TCR, val); } static void booke_wdt_set(void) { on_each_cpu(__booke_wdt_set, NULL, 0); } static void __booke_wdt_ping(void *data) { mtspr(SPRN_TSR, TSR_ENW|TSR_WIS); } static void booke_wdt_ping(void) { on_each_cpu(__booke_wdt_ping, NULL, 0); } static void __booke_wdt_enable(void *data) { u32 val; /* clear status before enabling watchdog */ __booke_wdt_ping(NULL); val = mfspr(SPRN_TCR); val &= ~WDTP_MASK; val |= (TCR_WIE|TCR_WRC(WRC_CHIP)|WDTP(booke_wdt_period)); mtspr(SPRN_TCR, val); } /** * booke_wdt_disable - disable the watchdog on the given CPU * * This function is called on each CPU. It disables the watchdog on that CPU. * * TCR[WRC] cannot be changed once it has been set to non-zero, but we can * effectively disable the watchdog by setting its period to the maximum value. */ static void __booke_wdt_disable(void *data) { u32 val; val = mfspr(SPRN_TCR); val &= ~(TCR_WIE | WDTP_MASK); mtspr(SPRN_TCR, val); /* clear status to make sure nothing is pending */ __booke_wdt_ping(NULL); } static ssize_t booke_wdt_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos) { booke_wdt_ping(); return count; } static struct watchdog_info ident = { .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING, .identity = "PowerPC Book-E Watchdog", }; static long booke_wdt_ioctl(struct file *file, unsigned int cmd, unsigned long arg) { u32 tmp = 0; u32 __user *p = (u32 __user *)arg; switch (cmd) { case WDIOC_GETSUPPORT: if (copy_to_user((void *)arg, &ident, sizeof(ident))) return -EFAULT; case WDIOC_GETSTATUS: return put_user(0, p); case WDIOC_GETBOOTSTATUS: /* XXX: something is clearing TSR */ tmp = mfspr(SPRN_TSR) & TSR_WRS(3); /* returns CARDRESET if last reset was caused by the WDT */ return (tmp ? WDIOF_CARDRESET : 0); case WDIOC_SETOPTIONS: if (get_user(tmp, p)) return -EINVAL; if (tmp == WDIOS_ENABLECARD) { booke_wdt_ping(); break; } else return -EINVAL; return 0; case WDIOC_KEEPALIVE: booke_wdt_ping(); return 0; case WDIOC_SETTIMEOUT: if (get_user(tmp, p)) return -EFAULT; #ifdef CONFIG_FSL_BOOKE /* period of 1 gives the largest possible timeout */ if (tmp > period_to_sec(1)) return -EINVAL; booke_wdt_period = sec_to_period(tmp); #else booke_wdt_period = tmp; #endif booke_wdt_set(); return 0; case WDIOC_GETTIMEOUT: return put_user(booke_wdt_period, p); default: return -ENOTTY; } return 0; } /* wdt_is_active stores wether or not the /dev/watchdog device is opened */ static unsigned long wdt_is_active; static int booke_wdt_open(struct inode *inode, struct file *file) { /* /dev/watchdog can only be opened once */ if (test_and_set_bit(0, &wdt_is_active)) return -EBUSY; spin_lock(&booke_wdt_lock); if (booke_wdt_enabled == 0) { booke_wdt_enabled = 1; on_each_cpu(__booke_wdt_enable, NULL, 0); printk(KERN_INFO "PowerPC Book-E Watchdog Timer Enabled (wdt_period=%d)\n", booke_wdt_period); } spin_unlock(&booke_wdt_lock); return nonseekable_open(inode, file); } static int booke_wdt_release(struct inode *inode, struct file *file) { #ifndef CONFIG_WATCHDOG_NOWAYOUT /* Normally, the watchdog is disabled when /dev/watchdog is closed, but * if CONFIG_WATCHDOG_NOWAYOUT is defined, then it means that the * watchdog should remain enabled. So we disable it only if * CONFIG_WATCHDOG_NOWAYOUT is not defined. */ on_each_cpu(__booke_wdt_disable, NULL, 0); booke_wdt_enabled = 0; #endif clear_bit(0, &wdt_is_active); return 0; } static const struct file_operations booke_wdt_fops = { .owner = THIS_MODULE, .llseek = no_llseek, .write = booke_wdt_write, .unlocked_ioctl = booke_wdt_ioctl, .open = booke_wdt_open, .release = booke_wdt_release, }; static struct miscdevice booke_wdt_miscdev = { .minor = WATCHDOG_MINOR, .name = "watchdog", .fops = &booke_wdt_fops, }; static void __exit booke_wdt_exit(void) { misc_deregister(&booke_wdt_miscdev); } static int __init booke_wdt_init(void) { int ret = 0; printk(KERN_INFO "PowerPC Book-E Watchdog Timer Loaded\n"); ident.firmware_version = cur_cpu_spec->pvr_value; ret = misc_register(&booke_wdt_miscdev); if (ret) { printk(KERN_CRIT "Cannot register miscdev on minor=%d: %d\n", WATCHDOG_MINOR, ret); return ret; } spin_lock(&booke_wdt_lock); if (booke_wdt_enabled == 1) { printk(KERN_INFO "PowerPC Book-E Watchdog Timer Enabled (wdt_period=%d)\n", booke_wdt_period); on_each_cpu(__booke_wdt_enable, NULL, 0); } spin_unlock(&booke_wdt_lock); return ret; } module_init(booke_wdt_init); module_exit(booke_wdt_exit); MODULE_DESCRIPTION("PowerPC Book-E watchdog driver"); MODULE_LICENSE("GPL");