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[WATCHDOG] mpc5200_wdt clean-up

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* 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>
This commit is contained in:
Wim Van Sebroeck 2007-07-20 21:22:58 +00:00
parent 7d831bf59a
commit de81225a87
1 changed files with 30 additions and 2 deletions
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32
drivers/char/watchdog/mpc5200_wdt.c
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@ -3,6 +3,7 @@
#include <linux/miscdevice.h> #include <linux/miscdevice.h>
#include <linux/watchdog.h> #include <linux/watchdog.h>
#include <linux/io.h> #include <linux/io.h>
#include <linux/spinlock.h>
#include <asm/of_platform.h> #include <asm/of_platform.h>
#include <asm/uaccess.h> #include <asm/uaccess.h>
#include <asm/mpc52xx.h> #include <asm/mpc52xx.h>
@ -19,8 +20,11 @@ struct mpc5200_wdt {
struct miscdevice miscdev; struct miscdevice miscdev;
struct resource mem; struct resource mem;
struct mpc52xx_gpt __iomem *regs; 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 /* 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... * file operations, which sucks. But there can be max 1 watchdog anyway, so...
@ -47,24 +51,31 @@ static int mpc5200_wdt_get_timeout(struct mpc5200_wdt *wdt)
/* watchdog operations */ /* watchdog operations */
static int mpc5200_wdt_start(struct mpc5200_wdt *wdt) static int mpc5200_wdt_start(struct mpc5200_wdt *wdt)
{ {
spin_lock(&wdt->io_lock);
/* disable */ /* disable */
out_be32(&wdt->regs->mode, 0); out_be32(&wdt->regs->mode, 0);
/* set timeout, with maximum prescaler */ /* set timeout, with maximum prescaler */
out_be32(&wdt->regs->count, 0x0 | wdt->count); out_be32(&wdt->regs->count, 0x0 | wdt->count);
/* enable watchdog */ /* enable watchdog */
out_be32(&wdt->regs->mode, GPT_MODE_CE | GPT_MODE_WDT | GPT_MODE_MS_TIMER); out_be32(&wdt->regs->mode, GPT_MODE_CE | GPT_MODE_WDT | GPT_MODE_MS_TIMER);
spin_unlock(&wdt->io_lock);
return 0; return 0;
} }
static int mpc5200_wdt_ping(struct mpc5200_wdt *wdt) static int mpc5200_wdt_ping(struct mpc5200_wdt *wdt)
{ {
spin_lock(&wdt->io_lock);
/* writing A5 to OCPW resets the watchdog */ /* writing A5 to OCPW resets the watchdog */
out_be32(&wdt->regs->mode, 0xA5000000 | (0xffffff & in_be32(&wdt->regs->mode))); out_be32(&wdt->regs->mode, 0xA5000000 | (0xffffff & in_be32(&wdt->regs->mode)));
spin_unlock(&wdt->io_lock);
return 0; return 0;
} }
static int mpc5200_wdt_stop(struct mpc5200_wdt *wdt) static int mpc5200_wdt_stop(struct mpc5200_wdt *wdt)
{ {
spin_lock(&wdt->io_lock);
/* disable */
out_be32(&wdt->regs->mode, 0); out_be32(&wdt->regs->mode, 0);
spin_unlock(&wdt->io_lock);
return 0; return 0;
} }
@ -91,11 +102,17 @@ static int mpc5200_wdt_ioctl(struct inode *inode, struct file *file,
switch (cmd) { switch (cmd) {
case WDIOC_GETSUPPORT: 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) if (ret)
ret = -EFAULT; ret = -EFAULT;
break; break;
case WDIOC_GETSTATUS:
case WDIOC_GETBOOTSTATUS:
ret = put_user(0, data);
break;
case WDIOC_KEEPALIVE: case WDIOC_KEEPALIVE:
mpc5200_wdt_ping(wdt); mpc5200_wdt_ping(wdt);
break; break;
@ -112,15 +129,23 @@ static int mpc5200_wdt_ioctl(struct inode *inode, struct file *file,
timeout = mpc5200_wdt_get_timeout(wdt); timeout = mpc5200_wdt_get_timeout(wdt);
ret = put_user(timeout, data); ret = put_user(timeout, data);
break; break;
default:
ret = -ENOTTY;
} }
return ret; return ret;
} }
static int mpc5200_wdt_open(struct inode *inode, struct file *file) 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_set_timeout(wdt_global, 30);
mpc5200_wdt_start(wdt_global); mpc5200_wdt_start(wdt_global);
file->private_data = 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) static int mpc5200_wdt_release(struct inode *inode, struct file *file)
{ {
@ -129,6 +154,7 @@ static int mpc5200_wdt_release(struct inode *inode, struct file *file)
mpc5200_wdt_stop(wdt); mpc5200_wdt_stop(wdt);
wdt->count = 0; /* == disabled */ wdt->count = 0; /* == disabled */
#endif #endif
clear_bit(0, &is_active);
return 0; return 0;
} }
@ -173,6 +199,7 @@ static int mpc5200_wdt_probe(struct of_device *op, const struct of_device_id *ma
} }
dev_set_drvdata(&op->dev, wdt); dev_set_drvdata(&op->dev, wdt);
spin_lock_init(&wdt->io_lock);
wdt->miscdev = (struct miscdevice) { wdt->miscdev = (struct miscdevice) {
.minor = WATCHDOG_MINOR, .minor = WATCHDOG_MINOR,
@ -256,3 +283,4 @@ module_exit(mpc5200_wdt_exit);
MODULE_AUTHOR("Domen Puncer <domen.puncer@telargo.com>"); MODULE_AUTHOR("Domen Puncer <domen.puncer@telargo.com>");
MODULE_LICENSE("Dual BSD/GPL"); MODULE_LICENSE("Dual BSD/GPL");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);