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watchdog: qcom: register a restart notifier

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The WDT's BITE_TIME warm-reset behavior can be leveraged as a last
resort mechanism for triggering chip reset.  Usually, other restart
methods (such as PS_HOLD) are preferrable for issuing a more complete
reset of the chip.  As such, keep the priority of the watchdog notifier
low.

Signed-off-by: Josh Cartwright <joshc@codeaurora.org>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
This commit is contained in:
Josh Cartwright 2014-09-25 17:51:04 -05:00 • committed by Wim Van Sebroeck
parent f286e1335f
commit 05e487d905
1 changed files with 38 additions and 0 deletions
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38
drivers/watchdog/qcom-wdt.c
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@ -11,11 +11,13 @@
* *
*/ */
#include <linux/clk.h> #include <linux/clk.h>
#include <linux/delay.h>
#include <linux/io.h> #include <linux/io.h>
#include <linux/kernel.h> #include <linux/kernel.h>
#include <linux/module.h> #include <linux/module.h>
#include <linux/of.h> #include <linux/of.h>
#include <linux/platform_device.h> #include <linux/platform_device.h>
#include <linux/reboot.h>
#include <linux/watchdog.h> #include <linux/watchdog.h>
#define WDT_RST 0x0 #define WDT_RST 0x0
@ -26,6 +28,7 @@ struct qcom_wdt {
struct watchdog_device wdd; struct watchdog_device wdd;
struct clk *clk; struct clk *clk;
unsigned long rate; unsigned long rate;
struct notifier_block restart_nb;
void __iomem *base; void __iomem *base;
}; };
@ -84,6 +87,32 @@ static const struct watchdog_info qcom_wdt_info = {
.identity = KBUILD_MODNAME, .identity = KBUILD_MODNAME,
}; };
static int qcom_wdt_restart(struct notifier_block *nb, unsigned long action,
void *data)
{
struct qcom_wdt *wdt = container_of(nb, struct qcom_wdt, restart_nb);
u32 timeout;
/*
* Trigger watchdog bite:
* Setup BITE_TIME to be 128ms, and enable WDT.
*/
timeout = 128 * wdt->rate / 1000;
writel(0, wdt->base + WDT_EN);
writel(1, wdt->base + WDT_RST);
writel(timeout, wdt->base + WDT_BITE_TIME);
writel(1, wdt->base + WDT_EN);
/*
* Actually make sure the above sequence hits hardware before sleeping.
*/
wmb();
msleep(150);
return NOTIFY_DONE;
}
static int qcom_wdt_probe(struct platform_device *pdev) static int qcom_wdt_probe(struct platform_device *pdev)
{ {
struct qcom_wdt *wdt; struct qcom_wdt *wdt;
@ -147,6 +176,14 @@ static int qcom_wdt_probe(struct platform_device *pdev)
goto err_clk_unprepare; goto err_clk_unprepare;
} }
/*
* WDT restart notifier has priority 0 (use as a last resort)
*/
wdt->restart_nb.notifier_call = qcom_wdt_restart;
ret = register_restart_handler(&wdt->restart_nb);
if (ret)
dev_err(&pdev->dev, "failed to setup restart handler\n");
platform_set_drvdata(pdev, wdt); platform_set_drvdata(pdev, wdt);
return 0; return 0;
@ -159,6 +196,7 @@ static int qcom_wdt_remove(struct platform_device *pdev)
{ {
struct qcom_wdt *wdt = platform_get_drvdata(pdev); struct qcom_wdt *wdt = platform_get_drvdata(pdev);
unregister_restart_handler(&wdt->restart_nb);
watchdog_unregister_device(&wdt->wdd); watchdog_unregister_device(&wdt->wdd);
clk_disable_unprepare(wdt->clk); clk_disable_unprepare(wdt->clk);
return 0; return 0;