[PATCH] powerpc: Add support for the MPC83xx watchdog

Add support for the PowerPC MPC83xx watchdog.  The MPC83xx has a simple
watchdog that once enabled it can not be stopped, has some simple timeout
range selection, and the ability to either reset the processor or take a
machine check.

Signed-off-by: Dave Updegraff <dave@cray.org>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
Cc: Wim Van Sebroeck <wim@iguana.be>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 229 insertions, 0 deletions

diff --git a/drivers/char/watchdog/mpc83xx_wdt.c b/drivers/char/watchdog/mpc83xx_wdt.c
new file mode 100644
index 000000000000..5d6f5061603a
--- /dev/null
+++ b/drivers/char/watchdog/mpc83xx_wdt.c
@@ -0,0 +1,229 @@
+/*
+ * mpc83xx_wdt.c - MPC83xx watchdog userspace interface
+ *
+ * Authors: Dave Updegraff <dave@cray.org>
+ *          Kumar Gala <galak@kernel.crashing.org>
+ *              Attribution: from 83xx_wst: Florian Schirmer <jolt@tuxbox.org>
+ *                              ..and from sc520_wdt
+ *
+ * Note: it appears that you can only actually ENABLE or DISABLE the thing
+ * once after POR. Once enabled, you cannot disable, and vice versa.
+ *
+ * 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.
+ */
+
+#include <linux/config.h>
+#include <linux/fs.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/miscdevice.h>
+#include <linux/platform_device.h>
+#include <linux/module.h>
+#include <linux/watchdog.h>
+#include <asm/io.h>
+#include <asm/uaccess.h>
+
+struct mpc83xx_wdt {
+        __be32 res0;
+        __be32 swcrr; /* System watchdog control register */
+#define SWCRR_SWTC 0xFFFF0000 /* Software Watchdog Time Count. */
+#define SWCRR_SWEN 0x00000004 /* Watchdog Enable bit. */
+#define SWCRR_SWRI 0x00000002 /* Software Watchdog Reset/Interrupt Select bit.*/
+#define SWCRR_SWPR 0x00000001 /* Software Watchdog Counter Prescale bit. */
+        __be32 swcnr; /* System watchdog count register */
+        u8 res1[2];
+        __be16 swsrr; /* System watchdog service register */
+        u8 res2[0xF0];
+};
+
+static struct mpc83xx_wdt __iomem *wd_base;
+
+static u16 timeout = 0xffff;
+module_param(timeout, ushort, 0);
+MODULE_PARM_DESC(timeout, "Watchdog timeout in ticks. (0<timeout<65536, default=65535");
+
+static int reset = 1;
+module_param(reset, bool, 0);
+MODULE_PARM_DESC(reset, "Watchdog Interrupt/Reset Mode. 0 = interrupt, 1 = reset");
+
+/*
+ * We always prescale, but if someone really doesn't want to they can set this
+ * to 0
+ */
+static int prescale = 1;
+static unsigned int timeout_sec;
+
+static unsigned long wdt_is_open;
+static spinlock_t wdt_spinlock;
+
+static void mpc83xx_wdt_keepalive(void)
+{
+        /* Ping the WDT */
+        spin_lock(&wdt_spinlock);
+        out_be16(&wd_base->swsrr, 0x556c);
+        out_be16(&wd_base->swsrr, 0xaa39);
+        spin_unlock(&wdt_spinlock);
+}
+
+static ssize_t mpc83xx_wdt_write(struct file *file, const char __user *buf,
+                                 size_t count, loff_t *ppos)
+{
+        if (count)
+                mpc83xx_wdt_keepalive();
+        return count;
+}
+
+static int mpc83xx_wdt_open(struct inode *inode, struct file *file)
+{
+        u32 tmp = SWCRR_SWEN;
+        if (test_and_set_bit(0, &wdt_is_open))
+                return -EBUSY;
+
+        /* Once we start the watchdog we can't stop it */
+        __module_get(THIS_MODULE);
+
+        /* Good, fire up the show */
+        if (prescale)
+                tmp |= SWCRR_SWPR;
+        if (reset)
+                tmp |= SWCRR_SWRI;
+
+        tmp |= timeout << 16;
+
+        out_be32(&wd_base->swcrr, tmp);
+
+        return nonseekable_open(inode, file);
+}
+
+static int mpc83xx_wdt_release(struct inode *inode, struct file *file)
+{
+        printk(KERN_CRIT "Unexpected close, not stopping watchdog!\n");
+        mpc83xx_wdt_keepalive();
+        clear_bit(0, &wdt_is_open);
+        return 0;
+}
+
+static int mpc83xx_wdt_ioctl(struct inode *inode, struct file *file,
+                                unsigned int cmd, unsigned long arg)
+{
+        void __user *argp = (void __user *)arg;
+        int __user *p = argp;
+        static struct watchdog_info ident = {
+                .options = WDIOF_KEEPALIVEPING,
+                .firmware_version = 1,
+                .identity = "MPC83xx",
+        };
+
+        switch (cmd) {
+        case WDIOC_GETSUPPORT:
+                return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
+        case WDIOC_KEEPALIVE:
+                mpc83xx_wdt_keepalive();
+                return 0;
+        case WDIOC_GETTIMEOUT:
+                return put_user(timeout_sec, p);
+        default:
+                return -ENOIOCTLCMD;
+        }
+}
+
+static struct file_operations mpc83xx_wdt_fops = {
+        .owner          = THIS_MODULE,
+        .llseek         = no_llseek,
+        .write          = mpc83xx_wdt_write,
+        .ioctl          = mpc83xx_wdt_ioctl,
+        .open           = mpc83xx_wdt_open,
+        .release        = mpc83xx_wdt_release,
+};
+
+static struct miscdevice mpc83xx_wdt_miscdev = {
+        .minor  = WATCHDOG_MINOR,
+        .name   = "watchdog",
+        .fops   = &mpc83xx_wdt_fops,
+};
+
+static int __devinit mpc83xx_wdt_probe(struct platform_device *dev)
+{
+        struct resource *r;
+        int ret;
+        unsigned int *freq = dev->dev.platform_data;
+
+        /* get a pointer to the register memory */
+        r = platform_get_resource(dev, IORESOURCE_MEM, 0);
+
+        if (!r) {
+                ret = -ENODEV;
+                goto err_out;
+        }
+
+        wd_base = ioremap(r->start, sizeof (struct mpc83xx_wdt));
+
+        if (wd_base == NULL) {
+                ret = -ENOMEM;
+                goto err_out;
+        }
+
+        ret = misc_register(&mpc83xx_wdt_miscdev);
+        if (ret) {
+                printk(KERN_ERR "cannot register miscdev on minor=%d "
+                                "(err=%d)\n",
+                                WATCHDOG_MINOR, ret);
+                goto err_unmap;
+        }
+
+        /* Calculate the timeout in seconds */
+        if (prescale)
+                timeout_sec = (timeout * 0x10000) / (*freq);
+        else
+                timeout_sec = timeout / (*freq);
+
+        printk(KERN_INFO "WDT driver for MPC83xx initialized. "
+                "mode:%s timeout=%d (%d seconds)\n",
+                reset ? "reset":"interrupt", timeout, timeout_sec);
+
+        spin_lock_init(&wdt_spinlock);
+
+        return 0;
+
+err_unmap:
+        iounmap(wd_base);
+err_out:
+        return ret;
+}
+
+static int __devexit mpc83xx_wdt_remove(struct platform_device *dev)
+{
+        misc_deregister(&mpc83xx_wdt_miscdev);
+        iounmap(wd_base);
+
+        return 0;
+}
+
+static struct platform_driver mpc83xx_wdt_driver = {
+        .probe          = mpc83xx_wdt_probe,
+        .remove         = __devexit_p(mpc83xx_wdt_remove),
+        .driver         = {
+                .name   = "mpc83xx_wdt",
+        },
+};
+
+static int __init mpc83xx_wdt_init(void)
+{
+        return platform_driver_register(&mpc83xx_wdt_driver);
+}
+
+static void __exit mpc83xx_wdt_exit(void)
+{
+        platform_driver_unregister(&mpc83xx_wdt_driver);
+}
+
+module_init(mpc83xx_wdt_init);
+module_exit(mpc83xx_wdt_exit);
+
+MODULE_AUTHOR("Dave Updegraff, Kumar Gala");
+MODULE_DESCRIPTION("Driver for watchdog timer in MPC83xx uProcessor");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);