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Subject[PATCH] watchdog/imx2+: add support for pretimeout interrupt
This watchdog device provides pretimeout facilities:
Set some timeout value and get informed about imminent
watchdog activity thru interrupt.

Allow user to wait for this interrupt thru poll(2),
and to clear it thru read(2).

Signed-off-by: Oskar Schirmer <oskar@scara.com>
Cc: Wim Van Sebroeck <wim@iguana.be>
Cc: Wolfram Sang <w.sang@pengutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
---
Resubmitted as it probably got lost on first attempt (2012/05/31)
drivers/watchdog/imx2_wdt.c | 129 ++++++++++++++++++++++++++++++++++++++++++-
1 files changed, 128 insertions(+), 1 deletions(-)
diff --git a/drivers/watchdog/imx2_wdt.c b/drivers/watchdog/imx2_wdt.c
index bcfab2b..09172c8 100644
--- a/drivers/watchdog/imx2_wdt.c
+++ b/drivers/watchdog/imx2_wdt.c
@@ -21,11 +21,16 @@
*/

#include <linux/init.h>
+#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/miscdevice.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/platform_device.h>
+#include <linux/poll.h>
+#include <linux/sched.h>
+#include <linux/spinlock.h>
+#include <linux/wait.h>
#include <linux/watchdog.h>
#include <linux/clk.h>
#include <linux/fs.h>
@@ -49,6 +54,11 @@
#define IMX2_WDT_WRSR 0x04 /* Reset Status Register */
#define IMX2_WDT_WRSR_TOUT (1 << 1) /* -> Reset due to Timeout */

+#define IMX2_WDT_WICT 0x06 /* Interrupt Control Reg */
+#define IMX2_WDT_WICT_WIE (1 << 15) /* -> Interrupt Enable */
+#define IMX2_WDT_WICT_WTIS (1 << 14) /* -> Timer Interrupt Status */
+#define IMX2_WDT_WICT_WICT (0xFF << 0) /* -> Interrupt Count Timeout */
+
#define IMX2_WDT_MAX_TIME 128
#define IMX2_WDT_DEFAULT_TIME 60 /* in seconds */

@@ -64,6 +74,11 @@ static struct {
unsigned timeout;
unsigned long status;
struct timer_list timer; /* Pings the watchdog when closed */
+ int irq;
+ spinlock_t read_lock;
+ wait_queue_head_t read_q;
+ unsigned char pretimer_once;
+ unsigned char pretimer_data;
} imx2_wdt;

static struct miscdevice imx2_wdt_miscdev;
@@ -81,7 +96,8 @@ MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds (default="

static const struct watchdog_info imx2_wdt_info = {
.identity = "imx2+ watchdog",
- .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
+ .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE |
+ WDIOF_PRETIMEOUT,
};

static inline void imx2_wdt_setup(void)
@@ -148,6 +164,28 @@ static void imx2_wdt_set_timeout(int new_timeout)
__raw_writew(val, imx2_wdt.base + IMX2_WDT_WCR);
}

+static void imx2_wdt_set_pretimeout(int new_pretimeout)
+{
+ u16 val = new_pretimeout;
+
+ if (val > 0)
+ val = (val << 1) | IMX2_WDT_WICT_WIE;
+ __raw_writew(val, imx2_wdt.base + IMX2_WDT_WICT);
+}
+
+static void imx2_wdt_interrupt(int irq, void *dev_id)
+{
+ u16 val;
+ spin_lock(&imx2_wdt.read_lock);
+ val = __raw_readw(imx2_wdt.base + IMX2_WDT_WICT);
+ if (val & IMX2_WDT_WICT_WTIS) {
+ __raw_writew(val, imx2_wdt.base + IMX2_WDT_WICT);
+ imx2_wdt.pretimer_data = 1;
+ }
+ wake_up_interruptible(&imx2_wdt.read_q);
+ spin_unlock(&imx2_wdt.read_lock);
+}
+
static int imx2_wdt_open(struct inode *inode, struct file *file)
{
if (test_and_set_bit(IMX2_WDT_STATUS_OPEN, &imx2_wdt.status))
@@ -210,6 +248,26 @@ static long imx2_wdt_ioctl(struct file *file, unsigned int cmd,
case WDIOC_GETTIMEOUT:
return put_user(imx2_wdt.timeout, p);

+ case WDIOC_SETPRETIMEOUT:
+ if (get_user(new_value, p))
+ return -EFAULT;
+ if ((new_value < 0) || (new_value >= IMX2_WDT_MAX_TIME))
+ return -EINVAL;
+ if (imx2_wdt.irq < 0)
+ return -EINVAL;
+ if (imx2_wdt.pretimer_once)
+ return -EPERM;
+ imx2_wdt.pretimer_once = 1;
+ imx2_wdt_set_pretimeout(new_value);
+
+ case WDIOC_GETPRETIMEOUT:
+ val = __raw_readw(imx2_wdt.base + IMX2_WDT_WICT);
+ if (val & IMX2_WDT_WICT_WIE)
+ val = (val & IMX2_WDT_WICT_WICT) >> 1;
+ else
+ val = 0;
+ return put_user(val, p);
+
default:
return -ENOTTY;
}
@@ -237,6 +295,59 @@ static ssize_t imx2_wdt_write(struct file *file, const char __user *data,
return len;
}

+static ssize_t imx2_wdt_read(struct file *file, char __user *data,
+ size_t count, loff_t *ppos)
+{
+ wait_queue_t wait;
+ unsigned long flags;
+
+ if (count <= 0)
+ return 0;
+
+ spin_lock_irqsave(&imx2_wdt.read_lock, flags);
+ while (!imx2_wdt.pretimer_data) {
+ if (file->f_flags & O_NONBLOCK) {
+ spin_unlock_irqrestore(&imx2_wdt.read_lock, flags);
+ return -EAGAIN;
+ }
+
+ init_waitqueue_entry(&wait, current);
+ add_wait_queue(&imx2_wdt.read_q, &wait);
+ set_current_state(TASK_INTERRUPTIBLE);
+ spin_unlock_irqrestore(&imx2_wdt.read_lock, flags);
+ schedule();
+ spin_lock_irqsave(&imx2_wdt.read_lock, flags);
+ remove_wait_queue(&imx2_wdt.read_q, &wait);
+
+ if (signal_pending(current)) {
+ spin_unlock_irqrestore(&imx2_wdt.read_lock, flags);
+ return -ERESTARTSYS;
+ }
+ }
+
+ imx2_wdt.pretimer_data = 0;
+ spin_unlock_irqrestore(&imx2_wdt.read_lock, flags);
+ if (copy_to_user(data, &imx2_wdt.pretimer_data, 1))
+ return -EFAULT;
+
+ return 1;
+}
+
+static unsigned int imx2_wdt_poll(struct file *file, poll_table *wait)
+{
+ unsigned int mask = 0;
+ unsigned long flags;
+
+ poll_wait(file, &imx2_wdt.read_q, wait);
+
+ spin_lock_irqsave(&imx2_wdt.read_lock, flags);
+ if (imx2_wdt.pretimer_data)
+ mask |= POLLIN | POLLRDNORM;
+ spin_unlock_irqrestore(&imx2_wdt.read_lock, flags);
+
+ return mask;
+}
+
static const struct file_operations imx2_wdt_fops = {
.owner = THIS_MODULE,
.llseek = no_llseek,
@@ -244,6 +355,8 @@ static const struct file_operations imx2_wdt_fops = {
.open = imx2_wdt_open,
.release = imx2_wdt_close,
.write = imx2_wdt_write,
+ .read = imx2_wdt_read,
+ .poll = imx2_wdt_poll,
};

static struct miscdevice imx2_wdt_miscdev = {
@@ -282,6 +395,16 @@ static int __init imx2_wdt_probe(struct platform_device *pdev)

setup_timer(&imx2_wdt.timer, imx2_wdt_timer_ping, 0);

+ init_waitqueue_head(&imx2_wdt.read_q);
+ spin_lock_init(&imx2_wdt.read_lock);
+ imx2_wdt.irq = platform_get_irq(pdev, 0);
+ if (imx2_wdt.irq >= 0) {
+ ret = request_irq(imx2_wdt.irq, imx2_wdt_interrupt,
+ 0, "watchdog", pdev);
+ if (ret)
+ goto fail;
+ }
+
imx2_wdt_miscdev.parent = &pdev->dev;
ret = misc_register(&imx2_wdt_miscdev);
if (ret)
@@ -294,6 +417,8 @@ static int __init imx2_wdt_probe(struct platform_device *pdev)

fail:
imx2_wdt_miscdev.parent = NULL;
+ if (imx2_wdt.irq >= 0)
+ free_irq(imx2_wdt.irq, pdev);
clk_put(imx2_wdt.clk);
return ret;
}
@@ -301,6 +426,8 @@ fail:
static int __exit imx2_wdt_remove(struct platform_device *pdev)
{
misc_deregister(&imx2_wdt_miscdev);
+ if (imx2_wdt.irq >= 0)
+ free_irq(imx2_wdt.irq, pdev);

if (test_bit(IMX2_WDT_STATUS_STARTED, &imx2_wdt.status)) {
del_timer_sync(&imx2_wdt.timer);
--
1.7.5.4



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