summaryrefslogtreecommitdiff
path: root/drivers/watchdog/shwdt.c
diff options
context:
space:
mode:
Diffstat (limited to 'drivers/watchdog/shwdt.c')
-rw-r--r--drivers/watchdog/shwdt.c485
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);