[WATCHDOG] mpc5200_wdt clean-up
* Add MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
* Add mandatory WDIOC_GETSTATUS and WDIOC_GETBOOTSTATUS ioctl's.
* If unknown ioctl is used we should return -ENOTTY.
* All watchdog device drivers are VFSs (Virtual File Systems).
We thus return a nonseekable_open(inode, file) when we open the VFS.
* Make sure that /dev/watchdog can be opened by 1 parent
* Add spin-locking to prevent that forked children can disturb
each other's operations.
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
diff --git a/drivers/char/watchdog/mpc5200_wdt.c b/drivers/char/watchdog/mpc5200_wdt.c
index cc3299c..564143d 100644
--- a/drivers/char/watchdog/mpc5200_wdt.c
+++ b/drivers/char/watchdog/mpc5200_wdt.c
@@ -3,6 +3,7 @@
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/io.h>
+#include <linux/spinlock.h>
#include <asm/of_platform.h>
#include <asm/uaccess.h>
#include <asm/mpc52xx.h>
@@ -19,8 +20,11 @@
struct miscdevice miscdev;
struct resource mem;
struct mpc52xx_gpt __iomem *regs;
+ spinlock_t io_lock;
};
+/* is_active stores wether or not the /dev/watchdog device is opened */
+static unsigned long is_active;
/* misc devices don't provide a way, to get back to 'dev' or 'miscdev' from
* file operations, which sucks. But there can be max 1 watchdog anyway, so...
@@ -47,24 +51,31 @@
/* watchdog operations */
static int mpc5200_wdt_start(struct mpc5200_wdt *wdt)
{
+ spin_lock(&wdt->io_lock);
/* disable */
out_be32(&wdt->regs->mode, 0);
/* set timeout, with maximum prescaler */
out_be32(&wdt->regs->count, 0x0 | wdt->count);
/* enable watchdog */
out_be32(&wdt->regs->mode, GPT_MODE_CE | GPT_MODE_WDT | GPT_MODE_MS_TIMER);
+ spin_unlock(&wdt->io_lock);
return 0;
}
static int mpc5200_wdt_ping(struct mpc5200_wdt *wdt)
{
+ spin_lock(&wdt->io_lock);
/* writing A5 to OCPW resets the watchdog */
out_be32(&wdt->regs->mode, 0xA5000000 | (0xffffff & in_be32(&wdt->regs->mode)));
+ spin_unlock(&wdt->io_lock);
return 0;
}
static int mpc5200_wdt_stop(struct mpc5200_wdt *wdt)
{
+ spin_lock(&wdt->io_lock);
+ /* disable */
out_be32(&wdt->regs->mode, 0);
+ spin_unlock(&wdt->io_lock);
return 0;
}
@@ -91,11 +102,17 @@
switch (cmd) {
case WDIOC_GETSUPPORT:
- ret = copy_to_user(data, &mpc5200_wdt_info, sizeof(mpc5200_wdt_info));
+ ret = copy_to_user(data, &mpc5200_wdt_info,
+ sizeof(mpc5200_wdt_info));
if (ret)
ret = -EFAULT;
break;
+ case WDIOC_GETSTATUS:
+ case WDIOC_GETBOOTSTATUS:
+ ret = put_user(0, data);
+ break;
+
case WDIOC_KEEPALIVE:
mpc5200_wdt_ping(wdt);
break;
@@ -112,15 +129,23 @@
timeout = mpc5200_wdt_get_timeout(wdt);
ret = put_user(timeout, data);
break;
+
+ default:
+ ret = -ENOTTY;
}
return ret;
}
static int mpc5200_wdt_open(struct inode *inode, struct file *file)
{
+ /* /dev/watchdog can only be opened once */
+ if (test_and_set_bit(0, &is_active))
+ return -EBUSY;
+
+ /* Set and activate the watchdog */
mpc5200_wdt_set_timeout(wdt_global, 30);
mpc5200_wdt_start(wdt_global);
file->private_data = wdt_global;
- return 0;
+ return nonseekable_open(inode, file);
}
static int mpc5200_wdt_release(struct inode *inode, struct file *file)
{
@@ -129,6 +154,7 @@
mpc5200_wdt_stop(wdt);
wdt->count = 0; /* == disabled */
#endif
+ clear_bit(0, &is_active);
return 0;
}
@@ -173,6 +199,7 @@
}
dev_set_drvdata(&op->dev, wdt);
+ spin_lock_init(&wdt->io_lock);
wdt->miscdev = (struct miscdevice) {
.minor = WATCHDOG_MINOR,
@@ -256,3 +283,4 @@
MODULE_AUTHOR("Domen Puncer <domen.puncer@telargo.com>");
MODULE_LICENSE("Dual BSD/GPL");
+MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);