[WATCHDOG] mv64x60_wdt: Support the WDIOF_MAGICCLOSE feature

Disallow disabling of the watchdog timer unless a particular
character ('V') was recently written to the watchdog device.

Signed-off-by: Dale Farnsworth <dale@farnsworth.org>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

diff --git a/drivers/char/watchdog/mv64x60_wdt.c b/drivers/char/watchdog/mv64x60_wdt.c
index 009b9a2c6efaf8b7329fa15287b8e35a2396c5a2..e07007543d09ef626a65af4c684a736cadeb85d5 100644 (file)
--- a/drivers/char/watchdog/mv64x60_wdt.c
+++ b/drivers/char/watchdog/mv64x60_wdt.c
@@ -44,6 +44,7 @@ static int wdt_status;
 static void __iomem *mv64x60_wdt_regs;
 static int mv64x60_wdt_timeout;
 static unsigned int bus_clk;
+static char expect_close;
 
 static int nowayout = WATCHDOG_NOWAYOUT;
 module_param(nowayout, int, 0);
@@ -115,10 +116,14 @@ static int mv64x60_wdt_open(struct inode *inode, struct file *file)
 
 static int mv64x60_wdt_release(struct inode *inode, struct file *file)
 {
-       mv64x60_wdt_service();
-
-       if (!nowayout)
+       if (expect_close == 42)
                mv64x60_wdt_handler_disable();
+       else {
+               printk(KERN_CRIT
+                      "mv64x60_wdt: unexpected close, not stopping timer!\n");
+               mv64x60_wdt_service();
+       }
+       expect_close = 0;
 
        clear_bit(MV64x60_WDOG_FLAG_OPENED, &wdt_flags);
 
@@ -128,8 +133,22 @@ static int mv64x60_wdt_release(struct inode *inode, struct file *file)
 static ssize_t mv64x60_wdt_write(struct file *file, const char __user *data,
                                 size_t len, loff_t * ppos)
 {
-       if (len)
+       if (len) {
+               if (!nowayout) {
+                       size_t i;
+
+                       expect_close = 0;
+
+                       for (i = 0; i != len; i++) {
+                               char c;
+                               if(get_user(c, data + i))
+                                       return -EFAULT;
+                               if (c == 'V')
+                                       expect_close = 42;
+                       }
+               }
                mv64x60_wdt_service();
+       }
 
        return len;
 }
@@ -142,6 +161,7 @@ static int mv64x60_wdt_ioctl(struct inode *inode, struct file *file,
        void __user *argp = (void __user *)arg;
        static struct watchdog_info info = {
                .options =      WDIOF_SETTIMEOUT        |
+                               WDIOF_MAGICCLOSE        |
                                WDIOF_KEEPALIVEPING,
                .firmware_version = 0,
                .identity = "MV64x60 watchdog",