[PATCH v2] watchdog: qcom: support pre-timeout when the bark irq is available

[Jorge Ramirez-Ortiz <jorge.ramirez-ortiz@xxxxxxxxxx>]

Use the bark interrupt as the pre-timeout notifier whenever this
interrupt is available.

By default, the pretimeout notification shall occur one second earlier
than the timeout.

Signed-off-by: Jorge Ramirez-Ortiz <jorge.ramirez-ortiz@xxxxxxxxxx>
---
 drivers/watchdog/qcom-wdt.c | 63 ++++++++++++++++++++++++++++++++++---
 1 file changed, 58 insertions(+), 5 deletions(-)

diff --git a/drivers/watchdog/qcom-wdt.c b/drivers/watchdog/qcom-wdt.c
index 7be7f87be28f..2dd36914aa82 100644
--- a/drivers/watchdog/qcom-wdt.c
+++ b/drivers/watchdog/qcom-wdt.c
@@ -10,6 +10,8 @@
 #include <linux/platform_device.h>
 #include <linux/watchdog.h>
 #include <linux/of_device.h>
+#include <linux/interrupt.h>
+#include <linux/watchdog.h>
 
 enum wdt_reg {
 	WDT_RST,
@@ -41,6 +43,7 @@ struct qcom_wdt {
 	unsigned long		rate;
 	void __iomem		*base;
 	const u32		*layout;
+	const struct device	*dev;
 };
 
 static void __iomem *wdt_addr(struct qcom_wdt *wdt, enum wdt_reg reg)
@@ -54,15 +57,37 @@ struct qcom_wdt *to_qcom_wdt(struct watchdog_device *wdd)
 	return container_of(wdd, struct qcom_wdt, wdd);
 }
 
+static inline int qcom_wdt_enable(struct qcom_wdt *wdt)
+{
+	/* enable the bark interrupt */
+	if (wdt->wdd.info->options & WDIOF_PRETIMEOUT)
+		return 3;
+
+	return 1;
+}
+
+static irqreturn_t qcom_wdt_irq(int irq, void *cookie)
+{
+	struct watchdog_device *wdd = (struct watchdog_device *) cookie;
+
+	watchdog_notify_pretimeout(wdd);
+
+	return IRQ_HANDLED;
+}
+
 static int qcom_wdt_start(struct watchdog_device *wdd)
 {
 	struct qcom_wdt *wdt = to_qcom_wdt(wdd);
+	unsigned int bark = wdd->pretimeout;
+
+	if (!(wdd->info->options & WDIOF_PRETIMEOUT))
+		bark = wdd->timeout;
 
 	writel(0, wdt_addr(wdt, WDT_EN));
 	writel(1, wdt_addr(wdt, WDT_RST));
-	writel(wdd->timeout * wdt->rate, wdt_addr(wdt, WDT_BARK_TIME));
+	writel(bark * wdt->rate, wdt_addr(wdt, WDT_BARK_TIME));
 	writel(wdd->timeout * wdt->rate, wdt_addr(wdt, WDT_BITE_TIME));
-	writel(1, wdt_addr(wdt, WDT_EN));
+	writel(qcom_wdt_enable(wdt), wdt_addr(wdt, WDT_EN));
 	return 0;
 }
 
@@ -86,9 +111,18 @@ static int qcom_wdt_set_timeout(struct watchdog_device *wdd,
 				unsigned int timeout)
 {
 	wdd->timeout = timeout;
+
 	return qcom_wdt_start(wdd);
 }
 
+static int qcom_wdt_set_pretimeout(struct watchdog_device *wdd,
+				   unsigned int timeout)
+{
+	wdd->pretimeout = timeout;
+
+	return 0;
+}
+
 static int qcom_wdt_restart(struct watchdog_device *wdd, unsigned long action,
 			    void *data)
 {
@@ -105,7 +139,7 @@ static int qcom_wdt_restart(struct watchdog_device *wdd, unsigned long action,
 	writel(1, wdt_addr(wdt, WDT_RST));
 	writel(timeout, wdt_addr(wdt, WDT_BARK_TIME));
 	writel(timeout, wdt_addr(wdt, WDT_BITE_TIME));
-	writel(1, wdt_addr(wdt, WDT_EN));
+	writel(qcom_wdt_enable(wdt), wdt_addr(wdt, WDT_EN));
 
 	/*
 	 * Actually make sure the above sequence hits hardware before sleeping.
@@ -121,11 +155,12 @@ static const struct watchdog_ops qcom_wdt_ops = {
 	.stop		= qcom_wdt_stop,
 	.ping		= qcom_wdt_ping,
 	.set_timeout	= qcom_wdt_set_timeout,
+	.set_pretimeout	= qcom_wdt_set_pretimeout,
 	.restart        = qcom_wdt_restart,
 	.owner		= THIS_MODULE,
 };
 
-static const struct watchdog_info qcom_wdt_info = {
+static struct watchdog_info qcom_wdt_info = {
 	.options	= WDIOF_KEEPALIVEPING
 			| WDIOF_MAGICCLOSE
 			| WDIOF_SETTIMEOUT
@@ -146,7 +181,7 @@ static int qcom_wdt_probe(struct platform_device *pdev)
 	struct device_node *np = dev->of_node;
 	const u32 *regs;
 	u32 percpu_offset;
-	int ret;
+	int irq, ret;
 
 	regs = of_device_get_match_data(dev);
 	if (!regs) {
@@ -210,6 +245,7 @@ static int qcom_wdt_probe(struct platform_device *pdev)
 	wdt->wdd.max_timeout = 0x10000000U / wdt->rate;
 	wdt->wdd.parent = dev;
 	wdt->layout = regs;
+	wdt->dev = &pdev->dev;
 
 	if (readl(wdt_addr(wdt, WDT_STS)) & 1)
 		wdt->wdd.bootstatus = WDIOF_CARDRESET;
@@ -222,6 +258,23 @@ static int qcom_wdt_probe(struct platform_device *pdev)
 	wdt->wdd.timeout = min(wdt->wdd.max_timeout, 30U);
 	watchdog_init_timeout(&wdt->wdd, 0, dev);
 
+	irq = platform_get_irq(pdev, 0);
+	if (irq >= 0) {
+		/* enable the pre-timeout notification */
+		qcom_wdt_info.options |= WDIOF_PRETIMEOUT;
+
+		ret = devm_request_irq(&pdev->dev, irq, qcom_wdt_irq,
+				       IRQF_TRIGGER_RISING, "wdog_bark",
+				       &wdt->wdd);
+		if (ret) {
+			dev_err(&pdev->dev, "failed to request irq\n");
+			return ret;
+		}
+	}
+
+	if (qcom_wdt_info.options & WDIOF_PRETIMEOUT)
+		wdt->wdd.pretimeout = wdt->wdd.timeout - 1;
+
 	ret = devm_watchdog_register_device(dev, &wdt->wdd);
 	if (ret)
 		return ret;
-- 
2.23.0