[WATCHDOG] Add support for SB1 hardware watchdog
Support watchdog timers built into SiByte MIPS SoCs.
Signed-off-by: Andy Sharp <andy.sharp@onstor.com>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Cc: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
diff --git a/drivers/watchdog/sb_wdog.c b/drivers/watchdog/sb_wdog.c
new file mode 100644
index 0000000..b944314
--- /dev/null
+++ b/drivers/watchdog/sb_wdog.c
@@ -0,0 +1,353 @@
+/*
+ * Watchdog driver for SiByte SB1 SoCs
+ *
+ * Copyright (C) 2007 OnStor, Inc. * Andrew Sharp <andy.sharp@onstor.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@redhat.com>, All Rights Reserved.
+ * http://www.redhat.com
+ *
+ * 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.
+ *
+ */
+#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>
+
+
+/*
+ * 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)
+{
+ __raw_writeb(0, wdog - 0x10);
+ __raw_writeq(t & 0x7fffffUL, wdog);
+}
+
+/*
+ * 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)
+{
+ __raw_writeb(__raw_readb(wdog) | 1, wdog);
+}
+
+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 struct watchdog_info ident = {
+ .options = WDIOF_CARDRESET | WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
+ .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 {
+ printk(KERN_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 int sbwdog_ioctl(struct inode *inode, 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_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(__raw_readq(user_dog - 8) / 1000000, p);
+ break;
+
+ case WDIOC_KEEPALIVE:
+ sbwdog_pet(user_dog);
+ ret = 0;
+ 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,
+ .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) {
+ printk(KERN_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) {
+ printk (KERN_ERR "%s: cannot register reboot notifier (err=%d)\n",
+ ident.identity, ret);
+ return ret;
+ }
+
+ /*
+ * get the resources
+ */
+ ret = misc_register(&sbwdog_miscdev);
+ if (ret == 0) {
+ printk(KERN_INFO "%s: timeout is %ld.%ld secs\n", ident.identity,
+ timeout / 1000000, (timeout / 100000) % 10);
+ }
+
+ ret = request_irq(1, sbwdog_interrupt, IRQF_DISABLED | IRQF_SHARED,
+ ident.identity, (void *)user_dog);
+ if (ret) {
+ printk(KERN_ERR "%s: failed to request irq 1 - %d\n", ident.identity,
+ ret);
+ misc_deregister(&sbwdog_miscdev);
+ }
+
+ return ret;
+}
+
+static void __exit sbwdog_exit(void)
+{
+ misc_deregister(&sbwdog_miscdev);
+}
+
+module_init(sbwdog_init);
+module_exit(sbwdog_exit);
+
+MODULE_AUTHOR("Andrew Sharp <andy.sharp@onstor.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");
+MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
+
+/*
+ * 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(0, sbwdog_interrupt, IRQF_DISABLED | IRQF_SHARED,
+ "Kernel Watchdog", IOADDR(A_SCD_WDOG_CFG_0));
+ if (ret) {
+ printk(KERN_CRIT "Watchdog IRQ zero(0) failed to be requested - %d\n",
+ ret);
+ }
+}
+
+
+ */