[WATCHDOG] Add a watchdog driver based on the CS5535/CS5536 MFGPT timers

Add a watchdog timer based on the MFGPT timers in the CS5535/CS5536
companion chips to the AMD Geode GX and LX processors.  Only caveat
is that the BIOS must provide at least a one free timer, and most
do not.

Signed-off-by: Jordan Crouse <jordan.crouse@amd.com>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

3 files changed, 323 insertions, 0 deletions

diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 254d115cafab..ccb78f66c2b6 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -295,6 +295,19 @@ config ALIM7101_WDT
 
           Most people will say N.
 
+config GEODE_WDT
+        tristate "AMD Geode CS5535/CS5536 Watchdog"
+        depends on MGEODE_LX
+        help
+          This driver enables a watchdog capability built into the
+          CS5535/CS5536 companion chips for the AMD Geode GX and LX
+          processors.  This watchdog watches your kernel to make sure
+          it doesn't freeze, and if it does, it reboots your computer after
+          a certain amount of time.
+
+          You can compile this driver directly into the kernel, or use
+          it as a module.  The module will be called geodewdt.
+
 config SC520_WDT
         tristate "AMD Elan SC520 processor Watchdog"
         depends on X86
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index f3fb170fe5c6..25b352b664d9 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -59,6 +59,7 @@ obj-$(CONFIG_ACQUIRE_WDT) += acquirewdt.o
 obj-$(CONFIG_ADVANTECH_WDT) += advantechwdt.o
 obj-$(CONFIG_ALIM1535_WDT) += alim1535_wdt.o
 obj-$(CONFIG_ALIM7101_WDT) += alim7101_wdt.o
+obj-$(CONFIG_GEODE_WDT) += geodewdt.o
 obj-$(CONFIG_SC520_WDT) += sc520_wdt.o
 obj-$(CONFIG_EUROTECH_WDT) += eurotechwdt.o
 obj-$(CONFIG_IB700_WDT) += ib700wdt.o
diff --git a/drivers/watchdog/geodewdt.c b/drivers/watchdog/geodewdt.c
new file mode 100644
index 000000000000..f85b19625f97
--- /dev/null
+++ b/drivers/watchdog/geodewdt.c
@@ -0,0 +1,309 @@
+/* Watchdog timer for the Geode GX/LX with the CS5535/CS5536 companion chip
+ *
+ * Copyright (C) 2006-2007, Advanced Micro Devices, Inc.
+ *
+ * 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/module.h>
+#include <linux/moduleparam.h>
+#include <linux/types.h>
+#include <linux/miscdevice.h>
+#include <linux/watchdog.h>
+#include <linux/fs.h>
+#include <linux/platform_device.h>
+#include <linux/reboot.h>
+
+#include <asm/uaccess.h>
+#include <asm/geode.h>
+
+#define GEODEWDT_HZ 500
+#define GEODEWDT_SCALE 6
+#define GEODEWDT_MAX_SECONDS 131
+
+#define WDT_FLAGS_OPEN 1
+#define WDT_FLAGS_ORPHAN 2
+
+#define DRV_NAME "geodewdt"
+#define WATCHDOG_NAME "Geode GX/LX WDT"
+#define WATCHDOG_TIMEOUT 60
+
+static int timeout = WATCHDOG_TIMEOUT;
+module_param(timeout, int, 0);
+MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds. 1<= timeout <=131, default=" __MODULE_STRING(WATCHDOG_TIMEOUT) ".");
+
+static int nowayout = WATCHDOG_NOWAYOUT;
+module_param(nowayout, int, 0);
+MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
+
+static struct platform_device *geodewdt_platform_device;
+static unsigned long wdt_flags;
+static int wdt_timer;
+static int safe_close;
+
+static void geodewdt_ping(void)
+{
+        /* Stop the counter */
+        geode_mfgpt_write(wdt_timer, MFGPT_REG_SETUP, 0);
+
+        /* Reset the counter */
+        geode_mfgpt_write(wdt_timer, MFGPT_REG_COUNTER, 0);
+
+        /* Enable the counter */
+        geode_mfgpt_write(wdt_timer, MFGPT_REG_SETUP, MFGPT_SETUP_CNTEN);
+}
+
+static void geodewdt_disable(void)
+{
+        geode_mfgpt_write(wdt_timer, MFGPT_REG_SETUP, 0);
+        geode_mfgpt_write(wdt_timer, MFGPT_REG_COUNTER, 0);
+}
+
+static int geodewdt_set_heartbeat(int val)
+{
+        if (val < 1 || val > GEODEWDT_MAX_SECONDS)
+                return -EINVAL;
+
+        geode_mfgpt_write(wdt_timer, MFGPT_REG_SETUP, 0);
+        geode_mfgpt_write(wdt_timer, MFGPT_REG_CMP2, val * GEODEWDT_HZ);
+        geode_mfgpt_write(wdt_timer, MFGPT_REG_COUNTER, 0);
+        geode_mfgpt_write(wdt_timer, MFGPT_REG_SETUP, MFGPT_SETUP_CNTEN);
+
+        timeout = val;
+        return 0;
+}
+
+static int
+geodewdt_open(struct inode *inode, struct file *file)
+{
+        if (test_and_set_bit(WDT_FLAGS_OPEN, &wdt_flags))
+                return -EBUSY;
+
+        if (!test_and_clear_bit(WDT_FLAGS_ORPHAN, &wdt_flags))
+                __module_get(THIS_MODULE);
+
+        geodewdt_ping();
+        return nonseekable_open(inode, file);
+}
+
+static int
+geodewdt_release(struct inode *inode, struct file *file)
+{
+        if (safe_close) {
+                geodewdt_disable();
+                module_put(THIS_MODULE);
+        }
+        else {
+                printk(KERN_CRIT "Unexpected close - watchdog is not stopping.\n");
+                geodewdt_ping();
+
+                set_bit(WDT_FLAGS_ORPHAN, &wdt_flags);
+        }
+
+        clear_bit(WDT_FLAGS_OPEN, &wdt_flags);
+        safe_close = 0;
+        return 0;
+}
+
+static ssize_t
+geodewdt_write(struct file *file, const char __user *data, size_t len,
+               loff_t *ppos)
+{
+        if(len) {
+                if (!nowayout) {
+                        size_t i;
+                        safe_close = 0;
+
+                        for (i = 0; i != len; i++) {
+                                char c;
+
+                                if (get_user(c, data + i))
+                                        return -EFAULT;
+
+                                if (c == 'V')
+                                        safe_close = 1;
+                        }
+                }
+
+                geodewdt_ping();
+        }
+        return len;
+}
+
+static int
+geodewdt_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
+               unsigned long arg)
+{
+        void __user *argp = (void __user *)arg;
+        int __user *p = argp;
+        int interval;
+
+        static struct watchdog_info ident = {
+                .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING
+                | WDIOF_MAGICCLOSE,
+                .firmware_version =     1,
+                .identity =             WATCHDOG_NAME,
+        };
+
+        switch(cmd) {
+        case WDIOC_GETSUPPORT:
+                return copy_to_user(argp, &ident,
+                                    sizeof(ident)) ? -EFAULT : 0;
+                break;
+
+        case WDIOC_GETSTATUS:
+        case WDIOC_GETBOOTSTATUS:
+                return put_user(0, p);
+
+        case WDIOC_KEEPALIVE:
+                geodewdt_ping();
+                return 0;
+
+        case WDIOC_SETTIMEOUT:
+                if (get_user(interval, p))
+                        return -EFAULT;
+
+                if (geodewdt_set_heartbeat(interval))
+                        return -EINVAL;
+
+/* Fall through */
+
+        case WDIOC_GETTIMEOUT:
+                return put_user(timeout, p);
+
+        case WDIOC_SETOPTIONS:
+        {
+                int options, ret = -EINVAL;
+
+                if (get_user(options, p))
+                        return -EFAULT;
+
+                if (options & WDIOS_DISABLECARD) {
+                        geodewdt_disable();
+                        ret = 0;
+                }
+
+                if (options & WDIOS_ENABLECARD) {
+                        geodewdt_ping();
+                        ret = 0;
+                }
+
+                return ret;
+        }
+        default:
+                return -ENOTTY;
+        }
+
+        return 0;
+}
+
+static const struct file_operations geodewdt_fops = {
+        .owner          = THIS_MODULE,
+        .llseek         = no_llseek,
+        .write          = geodewdt_write,
+        .ioctl          = geodewdt_ioctl,
+        .open           = geodewdt_open,
+        .release        = geodewdt_release,
+};
+
+static struct miscdevice geodewdt_miscdev = {
+        .minor = WATCHDOG_MINOR,
+        .name = "watchdog",
+        .fops = &geodewdt_fops
+};
+
+static int __devinit
+geodewdt_probe(struct platform_device *dev)
+{
+        int ret, timer;
+
+        timer = geode_mfgpt_alloc_timer(MFGPT_TIMER_ANY,
+                                        MFGPT_DOMAIN_WORKING, THIS_MODULE);
+
+        if (timer == -1) {
+                printk(KERN_ERR "geodewdt:  No timers were available\n");
+                return -ENODEV;
+        }
+
+        wdt_timer = timer;
+
+        /* Set up the timer */
+
+        geode_mfgpt_write(wdt_timer, MFGPT_REG_SETUP,
+                          GEODEWDT_SCALE | (3 << 8));
+
+        /* Set up comparator 2 to reset when the event fires */
+        geode_mfgpt_toggle_event(wdt_timer, MFGPT_CMP2, MFGPT_EVENT_RESET, 1);
+
+        /* Set up the initial timeout */
+
+        geode_mfgpt_write(wdt_timer, MFGPT_REG_CMP2,
+                timeout * GEODEWDT_HZ);
+
+        ret = misc_register(&geodewdt_miscdev);
+
+        return ret;
+}
+
+static int __devexit
+geodewdt_remove(struct platform_device *dev)
+{
+        misc_deregister(&geodewdt_miscdev);
+        return 0;
+}
+
+static void
+geodewdt_shutdown(struct platform_device *dev)
+{
+        geodewdt_disable();
+}
+
+static struct platform_driver geodewdt_driver = {
+        .probe          = geodewdt_probe,
+        .remove         = __devexit_p(geodewdt_remove),
+        .shutdown       = geodewdt_shutdown,
+        .driver         = {
+                .owner  = THIS_MODULE,
+                .name   = DRV_NAME,
+        },
+};
+
+static int __init
+geodewdt_init(void)
+{
+        int ret;
+
+        ret = platform_driver_register(&geodewdt_driver);
+        if (ret)
+                return ret;
+
+        geodewdt_platform_device = platform_device_register_simple(DRV_NAME, -1, NULL, 0);
+        if (IS_ERR(geodewdt_platform_device)) {
+                ret = PTR_ERR(geodewdt_platform_device);
+                goto err;
+        }
+
+        return 0;
+err:
+        platform_driver_unregister(&geodewdt_driver);
+        return ret;
+}
+
+static void __exit
+geodewdt_exit(void)
+{
+        platform_device_unregister(geodewdt_platform_device);
+        platform_driver_unregister(&geodewdt_driver);
+}
+
+module_init(geodewdt_init);
+module_exit(geodewdt_exit);
+
+MODULE_AUTHOR("Advanced Micro Devices, Inc");
+MODULE_DESCRIPTION("Geode GX/LX Watchdog Driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);