On 11/24/2015 02:15 PM, Simon Arlott wrote:
Return the remaining time from the hardware control register.
Warn when the device is registered if the hardware watchdog is currently
running and report the remaining time left.
This is really two logical changes, isn't it ?
Nice trick to figure out if the watchdog is running.
What is the impact ? Will this result in interrupts ?
If so, would it make sense to _not_ reset the system after a timeout
in this case, but to keep pinging the watchdog while the watchdog device
is not open ?
Thanks,
Guenter
Signed-off-by: Simon Arlott <simon@xxxxxxxxxxx>
---
Changed "if (timeleft > 0)" to "if (hw->running)" when checking if a
warning should be printed, in case the time left is truncated down to
0 seconds.
drivers/watchdog/bcm63xx_wdt.c | 37 +++++++++++++++++++++++++++++++++++++
1 file changed, 37 insertions(+)
diff --git a/drivers/watchdog/bcm63xx_wdt.c b/drivers/watchdog/bcm63xx_wdt.c
index 3c7667a..9d099e0 100644
--- a/drivers/watchdog/bcm63xx_wdt.c
+++ b/drivers/watchdog/bcm63xx_wdt.c
@@ -14,6 +14,7 @@
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/clk.h>
+#include <linux/delay.h>
#include <linux/errno.h>
#include <linux/io.h>
#include <linux/kernel.h>
@@ -75,6 +76,19 @@ static int bcm63xx_wdt_stop(struct watchdog_device *wdd)
return 0;
}
+static unsigned int bcm63xx_wdt_get_timeleft(struct watchdog_device *wdd)
+{
+ struct bcm63xx_wdt_hw *hw = watchdog_get_drvdata(wdd);
+ unsigned long flags;
+ u32 val;
+
+ raw_spin_lock_irqsave(&hw->lock, flags);
+ val = __raw_readl(hw->regs + WDT_CTL_REG);
+ val /= hw->clock_hz;
+ raw_spin_unlock_irqrestore(&hw->lock, flags);
+ return val;
+}
+
static int bcm63xx_wdt_set_timeout(struct watchdog_device *wdd,
unsigned int timeout)
{
@@ -130,6 +144,7 @@ static struct watchdog_ops bcm63xx_wdt_ops = {
.owner = THIS_MODULE,
.start = bcm63xx_wdt_start,
.stop = bcm63xx_wdt_stop,
+ .get_timeleft = bcm63xx_wdt_get_timeleft,
.set_timeout = bcm63xx_wdt_set_timeout,
};
@@ -144,6 +159,8 @@ static int bcm63xx_wdt_probe(struct platform_device *pdev)
struct bcm63xx_wdt_hw *hw;
struct watchdog_device *wdd;
struct resource *r;
+ u32 timeleft1, timeleft2;
+ unsigned int timeleft;
int ret;
hw = devm_kzalloc(&pdev->dev, sizeof(*hw), GFP_KERNEL);
@@ -197,6 +214,23 @@ static int bcm63xx_wdt_probe(struct platform_device *pdev)
watchdog_init_timeout(wdd, 0, &pdev->dev);
watchdog_set_nowayout(wdd, nowayout);
+ /* Compare two reads of the time left value, 2 clock ticks apart */
+ rmb();
+ timeleft1 = __raw_readl(hw->regs + WDT_CTL_REG);
+ udelay(DIV_ROUND_UP(1000000, hw->clock_hz / 2));
+ /* Ensure the register is read twice */
+ rmb();
+ timeleft2 = __raw_readl(hw->regs + WDT_CTL_REG);
+
+ /* If the time left is changing, the watchdog is running */
+ if (timeleft1 != timeleft2) {
+ hw->running = true;
+ timeleft = bcm63xx_wdt_get_timeleft(wdd);
+ } else {
+ hw->running = false;
+ timeleft = 0;
+ }
+
ret = bcm63xx_timer_register(TIMER_WDT_ID, bcm63xx_wdt_isr, wdd);
if (ret < 0) {
dev_err(&pdev->dev, "failed to register wdt timer isr\n");
@@ -214,6 +248,8 @@ static int bcm63xx_wdt_probe(struct platform_device *pdev)
dev_name(wdd->dev), hw->regs,
wdd->timeout, wdd->max_timeout);
+ if (hw->running)
+ dev_alert(wdd->dev, "running, reboot in %us\n", timeleft);
return 0;
unregister_timer:
@@ -255,6 +291,7 @@ module_platform_driver(bcm63xx_wdt_driver);
MODULE_AUTHOR("Miguel Gaio <miguel.gaio@xxxxxxxxx>");
MODULE_AUTHOR("Florian Fainelli <florian@xxxxxxxxxxx>");
+MODULE_AUTHOR("Simon Arlott");
MODULE_DESCRIPTION("Driver for the Broadcom BCM63xx SoC watchdog");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:bcm63xx-wdt");
