diff options
Diffstat (limited to 'drivers/watchdog/sb_wdog.c')
| -rw-r--r-- | drivers/watchdog/sb_wdog.c | 361 |
1 files changed, 361 insertions, 0 deletions
diff --git a/drivers/watchdog/sb_wdog.c b/drivers/watchdog/sb_wdog.c new file mode 100644 index 000000000..3abae5077 --- /dev/null +++ b/drivers/watchdog/sb_wdog.c @@ -0,0 +1,361 @@ +/* + * Watchdog driver for SiByte SB1 SoCs + * + * Copyright (C) 2007 OnStor, Inc. * Andrew Sharp <andy.sharp@lsi.com> + * + * This driver is intended to make the second of two hardware watchdogs + * on the Sibyte 12XX and 11XX SoCs available to the user. There are two + * such devices available on the SoC, but it seems that there isn't an + * enumeration class for watchdogs in Linux like there is for RTCs. + * The second is used rather than the first because it uses IRQ 1, + * thereby avoiding all that IRQ 0 problematic nonsense. + * + * I have not tried this driver on a 1480 processor; it might work + * just well enough to really screw things up. + * + * It is a simple timer, and there is an interrupt that is raised the + * first time the timer expires. The second time it expires, the chip + * is reset and there is no way to redirect that NMI. Which could + * be problematic in some cases where this chip is sitting on the HT + * bus and has just taken responsibility for providing a cache block. + * Since the reset can't be redirected to the external reset pin, it is + * possible that other HT connected processors might hang and not reset. + * For Linux, a soft reset would probably be even worse than a hard reset. + * There you have it. + * + * The timer takes 23 bits of a 64 bit register (?) as a count value, + * and decrements the count every microsecond, for a max value of + * 0x7fffff usec or about 8.3ish seconds. + * + * This watchdog borrows some user semantics from the softdog driver, + * in that if you close the fd, it leaves the watchdog running, unless + * you previously wrote a 'V' to the fd, in which case it disables + * the watchdog when you close the fd like some other drivers. + * + * Based on various other watchdog drivers, which are probably all + * loosely based on something Alan Cox wrote years ago. + * + * (c) Copyright 1996 Alan Cox <alan@lxorguk.ukuu.org.uk>, + * All Rights Reserved. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * version 1 or 2 as published by the Free Software Foundation. + * + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include <linux/module.h> +#include <linux/io.h> +#include <linux/uaccess.h> +#include <linux/fs.h> +#include <linux/reboot.h> +#include <linux/miscdevice.h> +#include <linux/watchdog.h> +#include <linux/interrupt.h> + +#include <asm/sibyte/sb1250.h> +#include <asm/sibyte/sb1250_regs.h> +#include <asm/sibyte/sb1250_int.h> +#include <asm/sibyte/sb1250_scd.h> + +static DEFINE_SPINLOCK(sbwd_lock); + +/* + * set the initial count value of a timer + * + * wdog is the iomem address of the cfg register + */ +void sbwdog_set(char __iomem *wdog, unsigned long t) +{ + spin_lock(&sbwd_lock); + __raw_writeb(0, wdog); + __raw_writeq(t & 0x7fffffUL, wdog - 0x10); + spin_unlock(&sbwd_lock); +} + +/* + * cause the timer to [re]load it's initial count and start counting + * all over again + * + * wdog is the iomem address of the cfg register + */ +void sbwdog_pet(char __iomem *wdog) +{ + spin_lock(&sbwd_lock); + __raw_writeb(__raw_readb(wdog) | 1, wdog); + spin_unlock(&sbwd_lock); +} + +static unsigned long sbwdog_gate; /* keeps it to one thread only */ +static char __iomem *kern_dog = (char __iomem *)(IO_BASE + (A_SCD_WDOG_CFG_0)); +static char __iomem *user_dog = (char __iomem *)(IO_BASE + (A_SCD_WDOG_CFG_1)); +static unsigned long timeout = 0x7fffffUL; /* useconds: 8.3ish secs. */ +static int expect_close; + +static const struct watchdog_info ident = { + .options = WDIOF_CARDRESET | WDIOF_SETTIMEOUT | + WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE, + .identity = "SiByte Watchdog", +}; + +/* + * Allow only a single thread to walk the dog + */ +static int sbwdog_open(struct inode *inode, struct file *file) +{ + nonseekable_open(inode, file); + if (test_and_set_bit(0, &sbwdog_gate)) + return -EBUSY; + __module_get(THIS_MODULE); + + /* + * Activate the timer + */ + sbwdog_set(user_dog, timeout); + __raw_writeb(1, user_dog); + + return 0; +} + +/* + * Put the dog back in the kennel. + */ +static int sbwdog_release(struct inode *inode, struct file *file) +{ + if (expect_close == 42) { + __raw_writeb(0, user_dog); + module_put(THIS_MODULE); + } else { + pr_crit("%s: Unexpected close, not stopping watchdog!\n", + ident.identity); + sbwdog_pet(user_dog); + } + clear_bit(0, &sbwdog_gate); + expect_close = 0; + + return 0; +} + +/* + * 42 - the answer + */ +static ssize_t sbwdog_write(struct file *file, const char __user *data, + size_t len, loff_t *ppos) +{ + int i; + + if (len) { + /* + * restart the timer + */ + expect_close = 0; + + for (i = 0; i != len; i++) { + char c; + + if (get_user(c, data + i)) + return -EFAULT; + if (c == 'V') + expect_close = 42; + } + sbwdog_pet(user_dog); + } + + return len; +} + +static long sbwdog_ioctl(struct file *file, unsigned int cmd, + unsigned long arg) +{ + int ret = -ENOTTY; + unsigned long time; + void __user *argp = (void __user *)arg; + int __user *p = argp; + + switch (cmd) { + case WDIOC_GETSUPPORT: + ret = copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0; + break; + + case WDIOC_GETSTATUS: + case WDIOC_GETBOOTSTATUS: + ret = put_user(0, p); + break; + + case WDIOC_KEEPALIVE: + sbwdog_pet(user_dog); + ret = 0; + break; + + case WDIOC_SETTIMEOUT: + ret = get_user(time, p); + if (ret) + break; + + time *= 1000000; + if (time > 0x7fffffUL) { + ret = -EINVAL; + break; + } + timeout = time; + sbwdog_set(user_dog, timeout); + sbwdog_pet(user_dog); + + case WDIOC_GETTIMEOUT: + /* + * get the remaining count from the ... count register + * which is 1*8 before the config register + */ + ret = put_user((u32)__raw_readq(user_dog - 8) / 1000000, p); + break; + } + return ret; +} + +/* + * Notifier for system down + */ +static int sbwdog_notify_sys(struct notifier_block *this, unsigned long code, + void *erf) +{ + if (code == SYS_DOWN || code == SYS_HALT) { + /* + * sit and sit + */ + __raw_writeb(0, user_dog); + __raw_writeb(0, kern_dog); + } + + return NOTIFY_DONE; +} + +static const struct file_operations sbwdog_fops = { + .owner = THIS_MODULE, + .llseek = no_llseek, + .write = sbwdog_write, + .unlocked_ioctl = sbwdog_ioctl, + .open = sbwdog_open, + .release = sbwdog_release, +}; + +static struct miscdevice sbwdog_miscdev = { + .minor = WATCHDOG_MINOR, + .name = "watchdog", + .fops = &sbwdog_fops, +}; + +static struct notifier_block sbwdog_notifier = { + .notifier_call = sbwdog_notify_sys, +}; + +/* + * interrupt handler + * + * doesn't do a whole lot for user, but oh so cleverly written so kernel + * code can use it to re-up the watchdog, thereby saving the kernel from + * having to create and maintain a timer, just to tickle another timer, + * which is just so wrong. + */ +irqreturn_t sbwdog_interrupt(int irq, void *addr) +{ + unsigned long wd_init; + char *wd_cfg_reg = (char *)addr; + u8 cfg; + + cfg = __raw_readb(wd_cfg_reg); + wd_init = __raw_readq(wd_cfg_reg - 8) & 0x7fffff; + + /* + * if it's the second watchdog timer, it's for those users + */ + if (wd_cfg_reg == user_dog) + pr_crit("%s in danger of initiating system reset " + "in %ld.%01ld seconds\n", + ident.identity, + wd_init / 1000000, (wd_init / 100000) % 10); + else + cfg |= 1; + + __raw_writeb(cfg, wd_cfg_reg); + + return IRQ_HANDLED; +} + +static int __init sbwdog_init(void) +{ + int ret; + + /* + * register a reboot notifier + */ + ret = register_reboot_notifier(&sbwdog_notifier); + if (ret) { + pr_err("%s: cannot register reboot notifier (err=%d)\n", + ident.identity, ret); + return ret; + } + + /* + * get the resources + */ + + ret = request_irq(1, sbwdog_interrupt, IRQF_SHARED, + ident.identity, (void *)user_dog); + if (ret) { + pr_err("%s: failed to request irq 1 - %d\n", + ident.identity, ret); + goto out; + } + + ret = misc_register(&sbwdog_miscdev); + if (ret == 0) { + pr_info("%s: timeout is %ld.%ld secs\n", + ident.identity, + timeout / 1000000, (timeout / 100000) % 10); + return 0; + } + free_irq(1, (void *)user_dog); +out: + unregister_reboot_notifier(&sbwdog_notifier); + + return ret; +} + +static void __exit sbwdog_exit(void) +{ + misc_deregister(&sbwdog_miscdev); + free_irq(1, (void *)user_dog); + unregister_reboot_notifier(&sbwdog_notifier); +} + +module_init(sbwdog_init); +module_exit(sbwdog_exit); + +MODULE_AUTHOR("Andrew Sharp <andy.sharp@lsi.com>"); +MODULE_DESCRIPTION("SiByte Watchdog"); + +module_param(timeout, ulong, 0); +MODULE_PARM_DESC(timeout, + "Watchdog timeout in microseconds (max/default 8388607 or 8.3ish secs)"); + +MODULE_LICENSE("GPL"); + +/* + * example code that can be put in a platform code area to utilize the + * first watchdog timer for the kernels own purpose. + +void platform_wd_setup(void) +{ + int ret; + + ret = request_irq(1, sbwdog_interrupt, IRQF_SHARED, + "Kernel Watchdog", IOADDR(A_SCD_WDOG_CFG_0)); + if (ret) { + pr_crit("Watchdog IRQ zero(0) failed to be requested - %d\n", ret); + } +} + + + */ |