--- /dev/null
+/*
+ * AMD Elan SC520 processor Watchdog Timer driver
+ *
+ * Based on acquirewdt.c by Alan Cox,
+ * and sbc60xxwdt.c by Jakob Oestergaard <jakob@unthought.net>
+ *
+ * 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.
+ *
+ * The authors do NOT admit liability nor provide warranty for
+ * any of this software. This material is provided "AS-IS" in
+ * the hope that it may be useful for others.
+ *
+ * (c) Copyright 2001 Scott Jennings <linuxdrivers@oro.net>
+ * 9/27 - 2001 [Initial release]
+ *
+ * Additional fixes Alan Cox
+ * - Fixed formatting
+ * - Removed debug printks
+ * - Fixed SMP built kernel deadlock
+ * - Switched to private locks not lock_kernel
+ * - Used ioremap/writew/readw
+ * - Added NOWAYOUT support
+ * 4/12 - 2002 Changes by Rob Radez <rob@osinvestor.com>
+ * - Change comments
+ * - Eliminate fop_llseek
+ * - Change CONFIG_WATCHDOG_NOWAYOUT semantics
+ * - Add KERN_* tags to printks
+ * - fix possible wdt_is_open race
+ * - Report proper capabilities in watchdog_info
+ * - Add WDIOC_{GETSTATUS, GETBOOTSTATUS, SETTIMEOUT,
+ * GETTIMEOUT, SETOPTIONS} ioctls
+ * 09/8 - 2003 Changes by Wim Van Sebroeck <wim@iguana.be>
+ * - cleanup of trailing spaces
+ * - added extra printk's for startup problems
+ * - use module_param
+ * - made timeout (the emulated heartbeat) a module_param
+ * - made the keepalive ping an internal subroutine
+ * 3/27 - 2004 Changes by Sean Young <sean@mess.org>
+ * - set MMCR_BASE to 0xfffef000
+ * - CBAR does not need to be read
+ * - removed debugging printks
+ *
+ * This WDT driver is different from most other Linux WDT
+ * drivers in that the driver will ping the watchdog by itself,
+ * because this particular WDT has a very short timeout (1.6
+ * seconds) and it would be insane to count on any userspace
+ * daemon always getting scheduled within that time frame.
+ *
+ * This driver uses memory mapped IO, and spinlock.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/types.h>
+#include <linux/timer.h>
+#include <linux/miscdevice.h>
+#include <linux/watchdog.h>
+#include <linux/fs.h>
+#include <linux/ioport.h>
+#include <linux/notifier.h>
+#include <linux/reboot.h>
+#include <linux/init.h>
+#include <linux/jiffies.h>
+#include <linux/io.h>
+#include <linux/uaccess.h>
+
+
+/*
+ * The AMD Elan SC520 timeout value is 492us times a power of 2 (0-7)
+ *
+ * 0: 492us 2: 1.01s 4: 4.03s 6: 16.22s
+ * 1: 503ms 3: 2.01s 5: 8.05s 7: 32.21s
+ *
+ * We will program the SC520 watchdog for a timeout of 2.01s.
+ * If we reset the watchdog every ~250ms we should be safe.
+ */
+
+#define WDT_INTERVAL (HZ/4+1)
+
+/*
+ * We must not require too good response from the userspace daemon.
+ * Here we require the userspace daemon to send us a heartbeat
+ * char to /dev/watchdog every 30 seconds.
+ */
+
+#define WATCHDOG_TIMEOUT 30 /* 30 sec default timeout */
+/* in seconds, will be multiplied by HZ to get seconds to wait for a ping */
+static int timeout = WATCHDOG_TIMEOUT;
+module_param(timeout, int, 0);
+MODULE_PARM_DESC(timeout,
+ "Watchdog timeout in seconds. (1 <= timeout <= 3600, default="
+ __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
+
+static bool nowayout = WATCHDOG_NOWAYOUT;
+module_param(nowayout, bool, 0);
+MODULE_PARM_DESC(nowayout,
+ "Watchdog cannot be stopped once started (default="
+ __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
+
+/*
+ * AMD Elan SC520 - Watchdog Timer Registers
+ */
+#define MMCR_BASE 0xfffef000 /* The default base address */
+#define OFFS_WDTMRCTL 0xCB0 /* Watchdog Timer Control Register */
+
+/* WDT Control Register bit definitions */
+#define WDT_EXP_SEL_01 0x0001 /* [01] Time-out = 496 us (with 33 Mhz clk). */
+#define WDT_EXP_SEL_02 0x0002 /* [02] Time-out = 508 ms (with 33 Mhz clk). */
+#define WDT_EXP_SEL_03 0x0004 /* [03] Time-out = 1.02 s (with 33 Mhz clk). */
+#define WDT_EXP_SEL_04 0x0008 /* [04] Time-out = 2.03 s (with 33 Mhz clk). */
+#define WDT_EXP_SEL_05 0x0010 /* [05] Time-out = 4.07 s (with 33 Mhz clk). */
+#define WDT_EXP_SEL_06 0x0020 /* [06] Time-out = 8.13 s (with 33 Mhz clk). */
+#define WDT_EXP_SEL_07 0x0040 /* [07] Time-out = 16.27s (with 33 Mhz clk). */
+#define WDT_EXP_SEL_08 0x0080 /* [08] Time-out = 32.54s (with 33 Mhz clk). */
+#define WDT_IRQ_FLG 0x1000 /* [12] Interrupt Request Flag */
+#define WDT_WRST_ENB 0x4000 /* [14] Watchdog Timer Reset Enable */
+#define WDT_ENB 0x8000 /* [15] Watchdog Timer Enable */
+
+static __u16 __iomem *wdtmrctl;
+
+static void wdt_timer_ping(unsigned long);
+static DEFINE_TIMER(timer, wdt_timer_ping, 0, 0);
+static unsigned long next_heartbeat;
+static unsigned long wdt_is_open;
+static char wdt_expect_close;
+static DEFINE_SPINLOCK(wdt_spinlock);
+
+/*
+ * Whack the dog
+ */
+
+static void wdt_timer_ping(unsigned long data)
+{
+ /* If we got a heartbeat pulse within the WDT_US_INTERVAL
+ * we agree to ping the WDT
+ */
+ if (time_before(jiffies, next_heartbeat)) {
+ /* Ping the WDT */
+ spin_lock(&wdt_spinlock);
+ writew(0xAAAA, wdtmrctl);
+ writew(0x5555, wdtmrctl);
+ spin_unlock(&wdt_spinlock);
+
+ /* Re-set the timer interval */
+ mod_timer(&timer, jiffies + WDT_INTERVAL);
+ } else
+ pr_warn("Heartbeat lost! Will not ping the watchdog\n");
+}
+
+/*
+ * Utility routines
+ */
+
+static void wdt_config(int writeval)
+{
+ unsigned long flags;
+
+ /* buy some time (ping) */
+ spin_lock_irqsave(&wdt_spinlock, flags);
+ readw(wdtmrctl); /* ensure write synchronization */
+ writew(0xAAAA, wdtmrctl);
+ writew(0x5555, wdtmrctl);
+ /* unlock WDT = make WDT configuration register writable one time */
+ writew(0x3333, wdtmrctl);
+ writew(0xCCCC, wdtmrctl);
+ /* write WDT configuration register */
+ writew(writeval, wdtmrctl);
+ spin_unlock_irqrestore(&wdt_spinlock, flags);
+}
+
+static int wdt_startup(void)
+{
+ next_heartbeat = jiffies + (timeout * HZ);
+
+ /* Start the timer */
+ mod_timer(&timer, jiffies + WDT_INTERVAL);
+
+ /* Start the watchdog */
+ wdt_config(WDT_ENB | WDT_WRST_ENB | WDT_EXP_SEL_04);
+
+ pr_info("Watchdog timer is now enabled\n");
+ return 0;
+}
+
+static int wdt_turnoff(void)
+{
+ /* Stop the timer */
+ del_timer(&timer);
+
+ /* Stop the watchdog */
+ wdt_config(0);
+
+ pr_info("Watchdog timer is now disabled...\n");
+ return 0;
+}
+
+static int wdt_keepalive(void)
+{
+ /* user land ping */
+ next_heartbeat = jiffies + (timeout * HZ);
+ return 0;
+}
+
+static int wdt_set_heartbeat(int t)
+{
+ if ((t < 1) || (t > 3600)) /* arbitrary upper limit */
+ return -EINVAL;
+
+ timeout = t;
+ return 0;
+}
+
+/*
+ * /dev/watchdog handling
+ */
+
+static ssize_t fop_write(struct file *file, const char __user *buf,
+ size_t count, loff_t *ppos)
+{
+ /* See if we got the magic character 'V' and reload the timer */
+ if (count) {
+ if (!nowayout) {
+ size_t ofs;
+
+ /* note: just in case someone wrote the magic character
+ * five months ago... */
+ wdt_expect_close = 0;
+
+ /* now scan */
+ for (ofs = 0; ofs != count; ofs++) {
+ char c;
+ if (get_user(c, buf + ofs))
+ return -EFAULT;
+ if (c == 'V')
+ wdt_expect_close = 42;
+ }
+ }
+
+ /* Well, anyhow someone wrote to us, we should
+ return that favour */
+ wdt_keepalive();
+ }
+ return count;
+}
+
+static int fop_open(struct inode *inode, struct file *file)
+{
+ /* Just in case we're already talking to someone... */
+ if (test_and_set_bit(0, &wdt_is_open))
+ return -EBUSY;
+ if (nowayout)
+ __module_get(THIS_MODULE);
+
+ /* Good, fire up the show */
+ wdt_startup();
+ return nonseekable_open(inode, file);
+}
+
+static int fop_close(struct inode *inode, struct file *file)
+{
+ if (wdt_expect_close == 42)
+ wdt_turnoff();
+ else {
+ pr_crit("Unexpected close, not stopping watchdog!\n");
+ wdt_keepalive();
+ }
+ clear_bit(0, &wdt_is_open);
+ wdt_expect_close = 0;
+ return 0;
+}
+
+static long fop_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+ void __user *argp = (void __user *)arg;
+ int __user *p = argp;
+ static const struct watchdog_info ident = {
+ .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT
+ | WDIOF_MAGICCLOSE,
+ .firmware_version = 1,
+ .identity = "SC520",
+ };
+
+ switch (cmd) {
+ case WDIOC_GETSUPPORT:
+ return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
+ case WDIOC_GETSTATUS:
+ case WDIOC_GETBOOTSTATUS:
+ return put_user(0, p);
+ case WDIOC_SETOPTIONS:
+ {
+ int new_options, retval = -EINVAL;
+
+ if (get_user(new_options, p))
+ return -EFAULT;
+
+ if (new_options & WDIOS_DISABLECARD) {
+ wdt_turnoff();
+ retval = 0;
+ }
+
+ if (new_options & WDIOS_ENABLECARD) {
+ wdt_startup();
+ retval = 0;
+ }
+
+ return retval;
+ }
+ case WDIOC_KEEPALIVE:
+ wdt_keepalive();
+ return 0;
+ case WDIOC_SETTIMEOUT:
+ {
+ int new_timeout;
+
+ if (get_user(new_timeout, p))
+ return -EFAULT;
+
+ if (wdt_set_heartbeat(new_timeout))
+ return -EINVAL;
+
+ wdt_keepalive();
+ /* Fall through */
+ }
+ case WDIOC_GETTIMEOUT:
+ return put_user(timeout, p);
+ default:
+ return -ENOTTY;
+ }
+}
+
+static const struct file_operations wdt_fops = {
+ .owner = THIS_MODULE,
+ .llseek = no_llseek,
+ .write = fop_write,
+ .open = fop_open,
+ .release = fop_close,
+ .unlocked_ioctl = fop_ioctl,
+};
+
+static struct miscdevice wdt_miscdev = {
+ .minor = WATCHDOG_MINOR,
+ .name = "watchdog",
+ .fops = &wdt_fops,
+};
+
+/*
+ * Notifier for system down
+ */
+
+static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
+ void *unused)
+{
+ if (code == SYS_DOWN || code == SYS_HALT)
+ wdt_turnoff();
+ return NOTIFY_DONE;
+}
+
+/*
+ * The WDT needs to learn about soft shutdowns in order to
+ * turn the timebomb registers off.
+ */
+
+static struct notifier_block wdt_notifier = {
+ .notifier_call = wdt_notify_sys,
+};
+
+static void __exit sc520_wdt_unload(void)
+{
+ if (!nowayout)
+ wdt_turnoff();
+
+ /* Deregister */
+ misc_deregister(&wdt_miscdev);
+ unregister_reboot_notifier(&wdt_notifier);
+ iounmap(wdtmrctl);
+}
+
+static int __init sc520_wdt_init(void)
+{
+ int rc = -EBUSY;
+
+ /* Check that the timeout value is within it's range ;
+ if not reset to the default */
+ if (wdt_set_heartbeat(timeout)) {
+ wdt_set_heartbeat(WATCHDOG_TIMEOUT);
+ pr_info("timeout value must be 1 <= timeout <= 3600, using %d\n",
+ WATCHDOG_TIMEOUT);
+ }
+
+ wdtmrctl = ioremap(MMCR_BASE + OFFS_WDTMRCTL, 2);
+ if (!wdtmrctl) {
+ pr_err("Unable to remap memory\n");
+ rc = -ENOMEM;
+ goto err_out_region2;
+ }
+
+ rc = register_reboot_notifier(&wdt_notifier);
+ if (rc) {
+ pr_err("cannot register reboot notifier (err=%d)\n", rc);
+ goto err_out_ioremap;
+ }
+
+ rc = misc_register(&wdt_miscdev);
+ if (rc) {
+ pr_err("cannot register miscdev on minor=%d (err=%d)\n",
+ WATCHDOG_MINOR, rc);
+ goto err_out_notifier;
+ }
+
+ pr_info("WDT driver for SC520 initialised. timeout=%d sec (nowayout=%d)\n",
+ timeout, nowayout);
+
+ return 0;
+
+err_out_notifier:
+ unregister_reboot_notifier(&wdt_notifier);
+err_out_ioremap:
+ iounmap(wdtmrctl);
+err_out_region2:
+ return rc;
+}
+
+module_init(sc520_wdt_init);
+module_exit(sc520_wdt_unload);
+
+MODULE_AUTHOR("Scott and Bill Jennings");
+MODULE_DESCRIPTION(
+ "Driver for watchdog timer in AMD \"Elan\" SC520 uProcessor");
+MODULE_LICENSE("GPL");
Code Review / kvmfornfv.git / blobdiff