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Subject[RFC PATCH v2] watchdog: ep93xx: Use the WatchDog Timer Driver Core.
Date
Convert the ep93xx watchdog driver to using the WatchDog Timer Driver Core.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Wim Van Sebroeck <wim@iguana.be>
Cc: Mika Westerberg <mika.westerberg@linux.intel.com>

---
v2: use the pr_* functions instead of printk(KERN_* PFX
document the register magic numbers and bits
fold the register access functions into the callers
add WDIOF_KEEPALIVEPING to the options
fix the bootstatus use, any detected reset is reported as WDIOF_CARDRESET
add a boot message so the user can see what actually caused the reset
validate that the user's requested timeout is actually valid
fix a typo in the v1 patch (extra void in ep93xx_wdt_start)
fix ep93xx_wdt_exit, ep93xx_wdt_stop should be called not wdt_shutdown

diff --git a/drivers/watchdog/ep93xx_wdt.c b/drivers/watchdog/ep93xx_wdt.c
index 726b7df..4309db3 100644
--- a/drivers/watchdog/ep93xx_wdt.c
+++ b/drivers/watchdog/ep93xx_wdt.c
@@ -23,184 +23,102 @@
* - Add a few missing ioctls
*/

+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
#include <linux/module.h>
-#include <linux/fs.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/timer.h>
-#include <linux/uaccess.h>
#include <linux/io.h>
#include <mach/hardware.h>

#define WDT_VERSION "0.3"
-#define PFX "ep93xx_wdt: "

/* default timeout (secs) */
#define WDT_TIMEOUT 30

static int nowayout = WATCHDOG_NOWAYOUT;
+module_param(nowayout, int, 0);
+MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
+
static int timeout = WDT_TIMEOUT;
+module_param(timeout, int, 0);
+MODULE_PARM_DESC(timeout,
+ "Watchdog timeout in seconds. (1<=timeout<=3600, default="
+ __MODULE_STRING(WDT_TIMEOUT) ")");

static struct timer_list timer;
static unsigned long next_heartbeat;
-static unsigned long wdt_status;
-static unsigned long boot_status;
-
-#define WDT_IN_USE 0
-#define WDT_OK_TO_CLOSE 1

#define EP93XX_WDT_REG(x) (EP93XX_WATCHDOG_BASE + (x))
#define EP93XX_WDT_WATCHDOG EP93XX_WDT_REG(0x00)
#define EP93XX_WDT_WDSTATUS EP93XX_WDT_REG(0x04)

+/* Watchdog register write only values */
+#define EP93XX_WATCHDOG_RESTART 0x5555
+#define EP93XX_WATCHDOG_DISABLE 0xaa55
+#define EP93XX_WATCHDOG_ENABLE 0xaaaa
+
+/* Watchdog register read only bits */
+#define EP93XX_WATCHDOG_PLSDSN (1 << 6)
+#define EP93XX_WATCHDOG_OVRID (1 << 5)
+#define EP93XX_WATCHDOG_SWDIS (1 << 4)
+#define EP93XX_WATCHDOG_HWDIS (1 << 3)
+#define EP93XX_WATCHDOG_URST (1 << 2)
+#define EP93XX_WATCHDOG_3KRST (1 << 1)
+#define EP93XX_WATCHDOG_WD (1 << 0)
+#define EP93XX_WATCHDOG_RESET_MASK (0x07)
+
/* reset the wdt every ~200ms */
#define WDT_INTERVAL (HZ/5)

-static void wdt_enable(void)
-{
- __raw_writew(0xaaaa, EP93XX_WDT_WATCHDOG);
-}
-
-static void wdt_disable(void)
+static int ep93xx_wdt_start(struct watchdog_device *wdd)
{
- __raw_writew(0xaa55, EP93XX_WDT_WATCHDOG);
-}
-
-static inline void wdt_ping(void)
-{
- __raw_writew(0x5555, EP93XX_WDT_WATCHDOG);
-}
+ next_heartbeat = jiffies + (wdd->timeout * HZ);

-static void wdt_startup(void)
-{
- next_heartbeat = jiffies + (timeout * HZ);
-
- wdt_enable();
+ __raw_writew(EP93XX_WATCHDOG_ENABLE, EP93XX_WDT_WATCHDOG);
mod_timer(&timer, jiffies + WDT_INTERVAL);
+ return 0;
}

-static void wdt_shutdown(void)
+static int ep93xx_wdt_stop(struct watchdog_device *wdd)
{
del_timer_sync(&timer);
- wdt_disable();
+ __raw_writew(EP93XX_WATCHDOG_DISABLE, EP93XX_WDT_WATCHDOG);
+ return 0;
}

-static void wdt_keepalive(void)
+static int ep93xx_wdt_keepalive(struct watchdog_device *wdd)
{
/* user land ping */
- next_heartbeat = jiffies + (timeout * HZ);
-}
-
-static int ep93xx_wdt_open(struct inode *inode, struct file *file)
-{
- if (test_and_set_bit(WDT_IN_USE, &wdt_status))
- return -EBUSY;
-
- clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
-
- wdt_startup();
-
- return nonseekable_open(inode, file);
-}
-
-static ssize_t
-ep93xx_wdt_write(struct file *file, const char __user *data, size_t len,
- loff_t *ppos)
-{
- if (len) {
- if (!nowayout) {
- size_t i;
-
- clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
-
- for (i = 0; i != len; i++) {
- char c;
-
- if (get_user(c, data + i))
- return -EFAULT;
-
- if (c == 'V')
- set_bit(WDT_OK_TO_CLOSE, &wdt_status);
- else
- clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
- }
- }
- wdt_keepalive();
- }
-
- return len;
+ next_heartbeat = jiffies + (wdd->timeout * HZ);
+ return 0;
}

-static const struct watchdog_info ident = {
- .options = WDIOF_CARDRESET | WDIOF_MAGICCLOSE,
- .identity = "EP93xx Watchdog",
+static const struct watchdog_info ep93xx_wdt_ident = {
+ .options = WDIOF_CARDRESET | WDIOF_MAGICCLOSE |
+ WDIOF_KEEPALIVEPING,
+ .identity = "EP93xx Watchdog",
};

-static long ep93xx_wdt_ioctl(struct file *file,
- unsigned int cmd, unsigned long arg)
-{
- int ret = -ENOTTY;
-
- switch (cmd) {
- case WDIOC_GETSUPPORT:
- ret = copy_to_user((struct watchdog_info __user *)arg, &ident,
- sizeof(ident)) ? -EFAULT : 0;
- break;
-
- case WDIOC_GETSTATUS:
- ret = put_user(0, (int __user *)arg);
- break;
-
- case WDIOC_GETBOOTSTATUS:
- ret = put_user(boot_status, (int __user *)arg);
- break;
-
- case WDIOC_KEEPALIVE:
- wdt_keepalive();
- ret = 0;
- break;
-
- case WDIOC_GETTIMEOUT:
- /* actually, it is 0.250 seconds.... */
- ret = put_user(1, (int __user *)arg);
- break;
- }
- return ret;
-}
-
-static int ep93xx_wdt_release(struct inode *inode, struct file *file)
-{
- if (test_bit(WDT_OK_TO_CLOSE, &wdt_status))
- wdt_shutdown();
- else
- printk(KERN_CRIT PFX
- "Device closed unexpectedly - timer will not stop\n");
-
- clear_bit(WDT_IN_USE, &wdt_status);
- clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
-
- return 0;
-}
-
-static const struct file_operations ep93xx_wdt_fops = {
+static const struct watchdog_ops ep93xx_wdt_ops = {
.owner = THIS_MODULE,
- .write = ep93xx_wdt_write,
- .unlocked_ioctl = ep93xx_wdt_ioctl,
- .open = ep93xx_wdt_open,
- .release = ep93xx_wdt_release,
- .llseek = no_llseek,
+ .start = ep93xx_wdt_start,
+ .stop = ep93xx_wdt_stop,
+ .ping = ep93xx_wdt_keepalive,
};

-static struct miscdevice ep93xx_wdt_miscdev = {
- .minor = WATCHDOG_MINOR,
- .name = "watchdog",
- .fops = &ep93xx_wdt_fops,
+static struct watchdog_device ep93xx_wdd = {
+ .info = &ep93xx_wdt_ident,
+ .ops = &ep93xx_wdt_ops,
+ .min_timeout = 1,
+ .max_timeout = 3600,
};

static void ep93xx_timer_ping(unsigned long data)
{
if (time_before(jiffies, next_heartbeat))
- wdt_ping();
+ __raw_writew(EP93XX_WATCHDOG_RESTART, EP93XX_WDT_WATCHDOG);

/* Re-set the timer interval */
mod_timer(&timer, jiffies + WDT_INTERVAL);
@@ -208,45 +126,50 @@ static void ep93xx_timer_ping(unsigned long data)

static int __init ep93xx_wdt_init(void)
{
+ int v;
int err;

- err = misc_register(&ep93xx_wdt_miscdev);
-
- boot_status = __raw_readl(EP93XX_WDT_WATCHDOG) & 0x01 ? 1 : 0;
-
- printk(KERN_INFO PFX "EP93XX watchdog, driver version "
- WDT_VERSION "%s\n",
- (__raw_readl(EP93XX_WDT_WATCHDOG) & 0x08)
- ? " (nCS1 disable detected)" : "");
+ v = readl(EP93XX_WDT_WATCHDOG);
+ ep93xx_wdd.bootstatus = (v & EP93XX_WATCHDOG_RESET_MASK)
+ ? WDIOF_CARDRESET : 0;
+ if (ep93xx_wdd.bootstatus) {
+ /* Only a power-on-reset will clear these bits */
+ pr_info("Last reset was due to %s%s%s\n",
+ (v & EP93XX_WATCHDOG_WD) ? "- watchdog timeout " : "",
+ (v & EP93XX_WATCHDOG_3KRST) ? "- 3-key reset " : "",
+ (v & EP93XX_WATCHDOG_URST) ? "- user reset" : "");
+ }

- if (timeout < 1 || timeout > 3600) {
- timeout = WDT_TIMEOUT;
- printk(KERN_INFO PFX
- "timeout value must be 1<=x<=3600, using %d\n",
- timeout);
+ if (timeout < ep93xx_wdd.min_timeout ||
+ timeout > ep93xx_wdd.max_timeout) {
+ ep93xx_wdd.timeout = WDT_TIMEOUT;
+ pr_info("timeout value must be %d<=x<=%d, using %d\n",
+ ep93xx_wdd.min_timeout, ep93xx_wdd.max_timeout,
+ ep93xx_wdd.timeout);
+ } else {
+ ep93xx_wdd.timeout = timeout;
}

+ err = watchdog_register_device(&ep93xx_wdd);
+ if (err)
+ return err;
+
setup_timer(&timer, ep93xx_timer_ping, 1);
- return err;
+
+ pr_info("EP93XX watchdog, driver version " WDT_VERSION "%s\n",
+ (v & EP93XX_WATCHDOG_HWDIS) ? " (nCS1 disable detected)" : "");
+
+ return 0;
}
+module_init(ep93xx_wdt_init);

static void __exit ep93xx_wdt_exit(void)
{
- wdt_shutdown();
- misc_deregister(&ep93xx_wdt_miscdev);
+ ep93xx_wdt_stop(&ep93xx_wdd);
+ watchdog_unregister_device(&ep93xx_wdd);
}
-
-module_init(ep93xx_wdt_init);
module_exit(ep93xx_wdt_exit);

-module_param(nowayout, int, 0);
-MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
-
-module_param(timeout, int, 0);
-MODULE_PARM_DESC(timeout,
- "Watchdog timeout in seconds. (1<=timeout<=3600, default="
- __MODULE_STRING(WDT_TIMEOUT) ")");
-
MODULE_AUTHOR("Ray Lehtiniemi <rayl@mail.com>,"
"Alessandro Zummo <a.zummo@towertech.it>");
MODULE_DESCRIPTION("EP93xx Watchdog");

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