1 files changed, 485 insertions, 0 deletions
diff --git a/drivers/watchdog/shwdt.c b/drivers/watchdog/shwdt.c
new file mode 100644
index 000000000000..cecbedd473a4
--- /dev/null
+++ b/drivers/watchdog/shwdt.c
@@ -0,0 +1,485 @@
+/*
+ * 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/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 <linux/mm.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 void sh_wdt_ping(unsigned long data);
+
+static unsigned long shwdt_is_open;
+static struct watchdog_info sh_wdt_info;
+static char shwdt_expect_close;
+static DEFINE_TIMER(timer, sh_wdt_ping, 0, 0);
+static unsigned long next_heartbeat;
+
+#define WATCHDOG_HEARTBEAT 30			/* 30 sec default heartbeat */
+static int heartbeat = WATCHDOG_HEARTBEAT;	/* in seconds */
+
+static int nowayout = WATCHDOG_NOWAYOUT;
+
+/**
+ * 	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 inline 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 (unlikely((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_mmap - map WDT/CPG registers into userspace
+ * 	@file: file structure for the device
+ * 	@vma: VMA to map the registers into
+ *
+ * 	A simple mmap() implementation for the corner cases where the counter
+ * 	needs to be mapped in userspace directly. Due to the relatively small
+ * 	size of the area, neighbouring registers not necessarily tied to the
+ * 	CPG will also be accessible through the register page, so this remains
+ * 	configurable for users that really know what they're doing.
+ *
+ *	Additionaly, the register page maps in the CPG register base relative
+ *	to the nearest page-aligned boundary, which requires that userspace do
+ *	the appropriate CPU subtype math for calculating the page offset for
+ *	the counter value.
+ */
+static int sh_wdt_mmap(struct file *file, struct vm_area_struct *vma)
+{
+	int ret = -ENOSYS;
+
+#ifdef CONFIG_SH_WDT_MMAP
+	unsigned long addr;
+
+	/* Only support the simple cases where we map in a register page. */
+	if (((vma->vm_end - vma->vm_start) != PAGE_SIZE) || vma->vm_pgoff)
+		return -EINVAL;
+
+	/*
+	 * Pick WTCNT as the start, it's usually the first register after the
+	 * FRQCR, and neither one are generally page-aligned out of the box.
+	 */
+	addr = WTCNT & ~(PAGE_SIZE - 1);
+
+	vma->vm_flags |= VM_IO;
+	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
+
+	if (io_remap_pfn_range(vma, vma->vm_start, addr >> PAGE_SHIFT,
+			       PAGE_SIZE, vma->vm_page_prot)) {
+		printk(KERN_ERR PFX "%s: io_remap_pfn_range failed\n",
+		       __FUNCTION__);
+		return -EAGAIN;
+	}
+
+	ret = 0;
+#endif
+
+	return ret;
+}
+
+/**
+ * 	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 -ENOTTY;
+	}
+
+	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 const 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,
+	.mmap		= sh_wdt_mmap,
+};
+
+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);
+	}
+
+	rc = sh_wdt_set_heartbeat(heartbeat);
+	if (unlikely(rc)) {
+		heartbeat = WATCHDOG_HEARTBEAT;
+		printk(KERN_INFO PFX "heartbeat value must "
+		       "be 1<=x<=3600, using %d\n", heartbeat);
+	}
+
+	rc = register_reboot_notifier(&sh_wdt_notifier);
+	if (unlikely(rc)) {
+		printk(KERN_ERR PFX "Can't register reboot notifier (err=%d)\n",
+		       rc);
+		return rc;
+	}
+
+	rc = misc_register(&sh_wdt_miscdev);
+	if (unlikely(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). (default=" __MODULE_STRING(clock_division_ratio) ")");
+
+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=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
+
+module_init(sh_wdt_init);
+module_exit(sh_wdt_exit);