| /* |
| * Watchdog timer for PowerPC Book-E systems |
| * |
| * Author: Matthew McClintock |
| * Maintainer: Kumar Gala <galak@kernel.crashing.org> |
| * |
| * Copyright 2005, 2008, 2010-2011 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 <linux/module.h> |
| #include <linux/fs.h> |
| #include <linux/smp.h> |
| #include <linux/miscdevice.h> |
| #include <linux/notifier.h> |
| #include <linux/watchdog.h> |
| #include <linux/uaccess.h> |
| |
| #include <asm/reg_booke.h> |
| #include <asm/time.h> |
| #include <asm/div64.h> |
| |
| /* 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(); |
| /* Fall */ |
| case WDIOC_GETTIMEOUT: |
| #ifdef CONFIG_FSL_BOOKE |
| return put_user(period_to_sec(booke_wdt_period), p); |
| #else |
| return put_user(booke_wdt_period, p); |
| #endif |
| 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); |
| pr_debug("booke_wdt: watchdog enabled (timeout = %llu sec)\n", |
| period_to_sec(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; |
| pr_debug("booke_wdt: watchdog disabled\n"); |
| #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; |
| |
| pr_info("booke_wdt: powerpc book-e watchdog driver loaded\n"); |
| ident.firmware_version = cur_cpu_spec->pvr_value; |
| |
| ret = misc_register(&booke_wdt_miscdev); |
| if (ret) { |
| pr_err("booke_wdt: cannot register device (minor=%u, ret=%i)\n", |
| WATCHDOG_MINOR, ret); |
| return ret; |
| } |
| |
| spin_lock(&booke_wdt_lock); |
| if (booke_wdt_enabled == 1) { |
| pr_info("booke_wdt: watchdog enabled (timeout = %llu sec)\n", |
| period_to_sec(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"); |