diff options
Diffstat (limited to 'drivers/char/watchdog/shwdt.c')
| -rw-r--r-- | drivers/char/watchdog/shwdt.c | 452 |
1 files changed, 452 insertions, 0 deletions
diff --git a/drivers/char/watchdog/shwdt.c b/drivers/char/watchdog/shwdt.c new file mode 100644 index 000000000000..3bc9272a474c --- /dev/null +++ b/drivers/char/watchdog/shwdt.c @@ -0,0 +1,452 @@ +/* + * drivers/char/watchdog/shwdt.c + * + * Watchdog driver for integrated watchdog in the SuperH processors. + * + * Copyright (C) 2001, 2002, 2003 Paul Mundt <lethal@linux-sh.org> + * + * 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. + * + * 14-Dec-2001 Matt Domsch <Matt_Domsch@dell.com> + * Added nowayout module option to override CONFIG_WATCHDOG_NOWAYOUT + * + * 19-Apr-2002 Rob Radez <rob@osinvestor.com> + * Added expect close support, made emulated timeout runtime changeable + * general cleanups, add some ioctls + */ +#include <linux/config.h> +#include <linux/module.h> +#include <linux/moduleparam.h> +#include <linux/init.h> +#include <linux/types.h> +#include <linux/miscdevice.h> +#include <linux/watchdog.h> +#include <linux/reboot.h> +#include <linux/notifier.h> +#include <linux/ioport.h> +#include <linux/fs.h> + +#include <asm/io.h> +#include <asm/uaccess.h> +#include <asm/watchdog.h> + +#define PFX "shwdt: " + +/* + * Default clock division ratio is 5.25 msecs. For an additional table of + * values, consult the asm-sh/watchdog.h. Overload this at module load + * time. + * + * In order for this to work reliably we need to have HZ set to 1000 or + * something quite higher than 100 (or we need a proper high-res timer + * implementation that will deal with this properly), otherwise the 10ms + * resolution of a jiffy is enough to trigger the overflow. For things like + * the SH-4 and SH-5, this isn't necessarily that big of a problem, though + * for the SH-2 and SH-3, this isn't recommended unless the WDT is absolutely + * necssary. + * + * As a result of this timing problem, the only modes that are particularly + * feasible are the 4096 and the 2048 divisors, which yeild 5.25 and 2.62ms + * overflow periods respectively. + * + * Also, since we can't really expect userspace to be responsive enough + * before the overflow happens, we maintain two seperate timers .. One in + * the kernel for clearing out WOVF every 2ms or so (again, this depends on + * HZ == 1000), and another for monitoring userspace writes to the WDT device. + * + * As such, we currently use a configurable heartbeat interval which defaults + * to 30s. In this case, the userspace daemon is only responsible for periodic + * writes to the device before the next heartbeat is scheduled. If the daemon + * misses its deadline, the kernel timer will allow the WDT to overflow. + */ +static int clock_division_ratio = WTCSR_CKS_4096; + +#define next_ping_period(cks) msecs_to_jiffies(cks - 4) + +static unsigned long shwdt_is_open; +static struct watchdog_info sh_wdt_info; +static char shwdt_expect_close; +static struct timer_list timer; +static unsigned long next_heartbeat; + +#define WATCHDOG_HEARTBEAT 30 /* 30 sec default heartbeat */ +static int heartbeat = WATCHDOG_HEARTBEAT; /* in seconds */ + +#ifdef CONFIG_WATCHDOG_NOWAYOUT +static int nowayout = 1; +#else +static int nowayout = 0; +#endif + +/** + * sh_wdt_start - Start the Watchdog + * + * Starts the watchdog. + */ +static void sh_wdt_start(void) +{ + __u8 csr; + + next_heartbeat = jiffies + (heartbeat * HZ); + mod_timer(&timer, next_ping_period(clock_division_ratio)); + + csr = sh_wdt_read_csr(); + csr |= WTCSR_WT | clock_division_ratio; + sh_wdt_write_csr(csr); + + sh_wdt_write_cnt(0); + + /* + * These processors have a bit of an inconsistent initialization + * process.. starting with SH-3, RSTS was moved to WTCSR, and the + * RSTCSR register was removed. + * + * On the SH-2 however, in addition with bits being in different + * locations, we must deal with RSTCSR outright.. + */ + csr = sh_wdt_read_csr(); + csr |= WTCSR_TME; + csr &= ~WTCSR_RSTS; + sh_wdt_write_csr(csr); + +#ifdef CONFIG_CPU_SH2 + /* + * Whoever came up with the RSTCSR semantics must've been smoking + * some of the good stuff, since in addition to the WTCSR/WTCNT write + * brain-damage, it's managed to fuck things up one step further.. + * + * If we need to clear the WOVF bit, the upper byte has to be 0xa5.. + * but if we want to touch RSTE or RSTS, the upper byte has to be + * 0x5a.. + */ + csr = sh_wdt_read_rstcsr(); + csr &= ~RSTCSR_RSTS; + sh_wdt_write_rstcsr(csr); +#endif +} + +/** + * sh_wdt_stop - Stop the Watchdog + * + * Stops the watchdog. + */ +static void sh_wdt_stop(void) +{ + __u8 csr; + + del_timer(&timer); + + csr = sh_wdt_read_csr(); + csr &= ~WTCSR_TME; + sh_wdt_write_csr(csr); +} + +/** + * sh_wdt_keepalive - Keep the Userspace Watchdog Alive + * + * The Userspace watchdog got a KeepAlive: schedule the next heartbeat. + */ +static void sh_wdt_keepalive(void) +{ + next_heartbeat = jiffies + (heartbeat * HZ); +} + +/** + * sh_wdt_set_heartbeat - Set the Userspace Watchdog heartbeat + * + * Set the Userspace Watchdog heartbeat + */ +static int sh_wdt_set_heartbeat(int t) +{ + if ((t < 1) || (t > 3600)) /* arbitrary upper limit */ + return -EINVAL; + + heartbeat = t; + return 0; +} + +/** + * sh_wdt_ping - Ping the Watchdog + * + * @data: Unused + * + * Clears overflow bit, resets timer counter. + */ +static void sh_wdt_ping(unsigned long data) +{ + if (time_before(jiffies, next_heartbeat)) { + __u8 csr; + + csr = sh_wdt_read_csr(); + csr &= ~WTCSR_IOVF; + sh_wdt_write_csr(csr); + + sh_wdt_write_cnt(0); + + mod_timer(&timer, next_ping_period(clock_division_ratio)); + } else { + printk(KERN_WARNING PFX "Heartbeat lost! Will not ping the watchdog\n"); + } +} + +/** + * sh_wdt_open - Open the Device + * + * @inode: inode of device + * @file: file handle of device + * + * Watchdog device is opened and started. + */ +static int sh_wdt_open(struct inode *inode, struct file *file) +{ + if (test_and_set_bit(0, &shwdt_is_open)) + return -EBUSY; + if (nowayout) + __module_get(THIS_MODULE); + + sh_wdt_start(); + + return nonseekable_open(inode, file); +} + +/** + * sh_wdt_close - Close the Device + * + * @inode: inode of device + * @file: file handle of device + * + * Watchdog device is closed and stopped. + */ +static int sh_wdt_close(struct inode *inode, struct file *file) +{ + if (shwdt_expect_close == 42) { + sh_wdt_stop(); + } else { + printk(KERN_CRIT PFX "Unexpected close, not stopping watchdog!\n"); + sh_wdt_keepalive(); + } + + clear_bit(0, &shwdt_is_open); + shwdt_expect_close = 0; + + return 0; +} + +/** + * sh_wdt_write - Write to Device + * + * @file: file handle of device + * @buf: buffer to write + * @count: length of buffer + * @ppos: offset + * + * Pings the watchdog on write. + */ +static ssize_t sh_wdt_write(struct file *file, const char *buf, + size_t count, loff_t *ppos) +{ + if (count) { + if (!nowayout) { + size_t i; + + shwdt_expect_close = 0; + + for (i = 0; i != count; i++) { + char c; + if (get_user(c, buf + i)) + return -EFAULT; + if (c == 'V') + shwdt_expect_close = 42; + } + } + sh_wdt_keepalive(); + } + + return count; +} + +/** + * sh_wdt_ioctl - Query Device + * + * @inode: inode of device + * @file: file handle of device + * @cmd: watchdog command + * @arg: argument + * + * Query basic information from the device or ping it, as outlined by the + * watchdog API. + */ +static int sh_wdt_ioctl(struct inode *inode, struct file *file, + unsigned int cmd, unsigned long arg) +{ + int new_heartbeat; + int options, retval = -EINVAL; + + switch (cmd) { + case WDIOC_GETSUPPORT: + return copy_to_user((struct watchdog_info *)arg, + &sh_wdt_info, + sizeof(sh_wdt_info)) ? -EFAULT : 0; + case WDIOC_GETSTATUS: + case WDIOC_GETBOOTSTATUS: + return put_user(0, (int *)arg); + case WDIOC_KEEPALIVE: + sh_wdt_keepalive(); + return 0; + case WDIOC_SETTIMEOUT: + if (get_user(new_heartbeat, (int *)arg)) + return -EFAULT; + + if (sh_wdt_set_heartbeat(new_heartbeat)) + return -EINVAL; + + sh_wdt_keepalive(); + /* Fall */ + case WDIOC_GETTIMEOUT: + return put_user(heartbeat, (int *)arg); + case WDIOC_SETOPTIONS: + if (get_user(options, (int *)arg)) + return -EFAULT; + + if (options & WDIOS_DISABLECARD) { + sh_wdt_stop(); + retval = 0; + } + + if (options & WDIOS_ENABLECARD) { + sh_wdt_start(); + retval = 0; + } + + return retval; + default: + return -ENOIOCTLCMD; + } + + return 0; +} + +/** + * sh_wdt_notify_sys - Notifier Handler + * + * @this: notifier block + * @code: notifier event + * @unused: unused + * + * Handles specific events, such as turning off the watchdog during a + * shutdown event. + */ +static int sh_wdt_notify_sys(struct notifier_block *this, + unsigned long code, void *unused) +{ + if (code == SYS_DOWN || code == SYS_HALT) { + sh_wdt_stop(); + } + + return NOTIFY_DONE; +} + +static struct file_operations sh_wdt_fops = { + .owner = THIS_MODULE, + .llseek = no_llseek, + .write = sh_wdt_write, + .ioctl = sh_wdt_ioctl, + .open = sh_wdt_open, + .release = sh_wdt_close, +}; + +static struct watchdog_info sh_wdt_info = { + .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE, + .firmware_version = 1, + .identity = "SH WDT", +}; + +static struct notifier_block sh_wdt_notifier = { + .notifier_call = sh_wdt_notify_sys, +}; + +static struct miscdevice sh_wdt_miscdev = { + .minor = WATCHDOG_MINOR, + .name = "watchdog", + .fops = &sh_wdt_fops, +}; + +/** + * sh_wdt_init - Initialize module + * + * Registers the device and notifier handler. Actual device + * initialization is handled by sh_wdt_open(). + */ +static int __init sh_wdt_init(void) +{ + int rc; + + if ((clock_division_ratio < 0x5) || (clock_division_ratio > 0x7)) { + clock_division_ratio = WTCSR_CKS_4096; + printk(KERN_INFO PFX "clock_division_ratio value must be 0x5<=x<=0x7, using %d\n", + clock_division_ratio); + } + + if (sh_wdt_set_heartbeat(heartbeat)) + { + heartbeat = WATCHDOG_HEARTBEAT; + printk(KERN_INFO PFX "heartbeat value must be 1<=x<=3600, using %d\n", + heartbeat); + } + + init_timer(&timer); + timer.function = sh_wdt_ping; + timer.data = 0; + + rc = register_reboot_notifier(&sh_wdt_notifier); + if (rc) { + printk(KERN_ERR PFX "Can't register reboot notifier (err=%d)\n", rc); + return rc; + } + + rc = misc_register(&sh_wdt_miscdev); + if (rc) { + printk(KERN_ERR PFX "Can't register miscdev on minor=%d (err=%d)\n", + sh_wdt_miscdev.minor, rc); + unregister_reboot_notifier(&sh_wdt_notifier); + return rc; + } + + printk(KERN_INFO PFX "initialized. heartbeat=%d sec (nowayout=%d)\n", + heartbeat, nowayout); + + return 0; +} + +/** + * sh_wdt_exit - Deinitialize module + * + * Unregisters the device and notifier handler. Actual device + * deinitialization is handled by sh_wdt_close(). + */ +static void __exit sh_wdt_exit(void) +{ + misc_deregister(&sh_wdt_miscdev); + unregister_reboot_notifier(&sh_wdt_notifier); +} + +MODULE_AUTHOR("Paul Mundt <lethal@linux-sh.org>"); +MODULE_DESCRIPTION("SuperH watchdog driver"); +MODULE_LICENSE("GPL"); +MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); + +module_param(clock_division_ratio, int, 0); +MODULE_PARM_DESC(clock_division_ratio, "Clock division ratio. Valid ranges are from 0x5 (1.31ms) to 0x7 (5.25ms). Defaults to 0x7."); + +module_param(heartbeat, int, 0); +MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds. (1<=heartbeat<=3600, default=" __MODULE_STRING(WATCHDOG_HEARTBEAT) ")"); + +module_param(nowayout, int, 0); +MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=CONFIG_WATCHDOG_NOWAYOUT)"); + +module_init(sh_wdt_init); +module_exit(sh_wdt_exit); + |