[PATCH v4] watchdog: qcom: support pre-timeout when the bark irq is available

[Jorge Ramirez-Ortiz]

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>
---
 v4:
     address Guenter Roeck comments as follows:
       remove unnecessary include and private variable
       provide macro for WDT EN register values
       use pretimeout as per its API intent
       handle EPROBE_DEFER on get_irq
     also:
       handle the irq registration as done in pm8916_wdt.c
 v3:
    remove unnecesary variable added to private.

 v2:
    register the pre-timeout notifier instead.

 v1:
 drivers/watchdog/qcom-wdt.c | 64 ++++++++++++++++++++++++++++++++++---
 1 file changed, 59 insertions(+), 5 deletions(-)

diff --git a/drivers/watchdog/qcom-wdt.c b/drivers/watchdog/qcom-wdt.c
index 7be7f87be28f..0f1d29eeb81d 100644
--- a/drivers/watchdog/qcom-wdt.c
+++ b/drivers/watchdog/qcom-wdt.c
@@ -10,6 +10,7 @@
 #include <linux/platform_device.h>
 #include <linux/watchdog.h>
 #include <linux/of_device.h>
+#include <linux/interrupt.h>
 
 enum wdt_reg {
 	WDT_RST,
@@ -19,6 +20,9 @@ enum wdt_reg {
 	WDT_BITE_TIME,
 };
 
+#define QCOM_WDT_ENABLE		BIT(0)
+#define QCOM_WDT_ENABLE_IRQ	BIT(1)
+
 static const u32 reg_offset_data_apcs_tmr[] = {
 	[WDT_RST] = 0x38,
 	[WDT_EN] = 0x40,
@@ -54,15 +58,38 @@ struct qcom_wdt *to_qcom_wdt(struct watchdog_device *wdd)
 	return container_of(wdd, struct qcom_wdt, wdd);
 }
 
+static inline int qcom_get_enable(struct watchdog_device *wdd)
+{
+	int enable = QCOM_WDT_ENABLE;
+
+	if (wdd->info->options & WDIOF_PRETIMEOUT)
+		enable |= QCOM_WDT_ENABLE_IRQ;
+
+	return enable;
+}
+
+static irqreturn_t qcom_wdt_isr(int irq, void *arg)
+{
+	struct watchdog_device *wdd = arg;
+
+	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->timeout;
+
+	if (wdd->pretimeout)
+		bark = bark - wdd->pretimeout;
 
 	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_get_enable(wdd), wdt_addr(wdt, WDT_EN));
 	return 0;
 }
 
@@ -89,6 +116,13 @@ static int qcom_wdt_set_timeout(struct watchdog_device *wdd,
 	return qcom_wdt_start(wdd);
 }
 
+static int qcom_wdt_set_pretimeout(struct watchdog_device *wdd,
+				   unsigned int timeout)
+{
+	wdd->pretimeout = timeout;
+	return qcom_wdt_start(wdd);
+}
+
 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_get_enable(wdd), wdt_addr(wdt, WDT_EN));
 
 	/*
 	 * Actually make sure the above sequence hits hardware before sleeping.
@@ -121,6 +155,7 @@ 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,
 };
@@ -133,6 +168,15 @@ static const struct watchdog_info qcom_wdt_info = {
 	.identity	= KBUILD_MODNAME,
 };
 
+static const struct watchdog_info qcom_wdt_pt_info = {
+	.options	= WDIOF_KEEPALIVEPING
+			| WDIOF_MAGICCLOSE
+			| WDIOF_SETTIMEOUT
+			| WDIOF_PRETIMEOUT
+			| WDIOF_CARDRESET,
+	.identity	= KBUILD_MODNAME,
+};
+
 static void qcom_clk_disable_unprepare(void *data)
 {
 	clk_disable_unprepare(data);
@@ -146,7 +190,7 @@ 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) {
@@ -204,7 +248,17 @@ static int qcom_wdt_probe(struct platform_device *pdev)
 		return -EINVAL;
 	}
 
-	wdt->wdd.info = &qcom_wdt_info;
+	irq = platform_get_irq(pdev, 0);
+	if (irq > 0) {
+		if (devm_request_irq(dev, irq, qcom_wdt_isr,
+				     IRQF_TRIGGER_RISING, "wdt_bark",
+				     &wdt->wdd))
+			irq = 0;
+	} else if (irq == -EPROBE_DEFER)
+		return -EPROBE_DEFER;
+
+	wdt->wdd.info = irq > 0 ? &qcom_wdt_pt_info : &qcom_wdt_info;
+	wdt->wdd.pretimeout = irq > 0 ? 1 : 0;
 	wdt->wdd.ops = &qcom_wdt_ops;
 	wdt->wdd.min_timeout = 1;
 	wdt->wdd.max_timeout = 0x10000000U / wdt->rate;
-- 
2.23.0