[PATCH v3 2/2] watchdog: max63xx_wdt: Add support for specifying WDI logic via GPIO

["Pali Rohár" <pali@kernel.org>]

On some boards is WDI logic of max6370 chip connected via GPIO.
So extend max63xx_wdt driver to allow specifying WDI logic via GPIO.

Signed-off-by: Pali Rohár <pali@kernel.org>
---
Changes in v3:
* Use gpiod_set_value()
Changes in v2:
* Usage of dev_err_probe()
* Fixing assignment of wdt->ping
* Remove clearing of wdt->gpio_wdi
* Move YAML change to separate patch
---
 drivers/watchdog/max63xx_wdt.c | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/drivers/watchdog/max63xx_wdt.c b/drivers/watchdog/max63xx_wdt.c
index 9e1541cfae0d..4718695837f6 100644
--- a/drivers/watchdog/max63xx_wdt.c
+++ b/drivers/watchdog/max63xx_wdt.c
@@ -27,6 +27,7 @@
 #include <linux/io.h>
 #include <linux/slab.h>
 #include <linux/property.h>
+#include <linux/gpio/consumer.h>
 
 #define DEFAULT_HEARTBEAT 60
 #define MAX_HEARTBEAT     60
@@ -53,6 +54,9 @@ struct max63xx_wdt {
 	void __iomem *base;
 	spinlock_t lock;
 
+	/* GPIOs */
+	struct gpio_desc *gpio_wdi;
+
 	/* WDI and WSET bits write access routines */
 	void (*ping)(struct max63xx_wdt *wdt);
 	void (*set)(struct max63xx_wdt *wdt, u8 set);
@@ -158,6 +162,17 @@ static const struct watchdog_info max63xx_wdt_info = {
 	.identity = "max63xx Watchdog",
 };
 
+static void max63xx_gpio_ping(struct max63xx_wdt *wdt)
+{
+	spin_lock(&wdt->lock);
+
+	gpiod_set_value(wdt->gpio_wdi, 1);
+	udelay(1);
+	gpiod_set_value(wdt->gpio_wdi, 0);
+
+	spin_unlock(&wdt->lock);
+}
+
 static void max63xx_mmap_ping(struct max63xx_wdt *wdt)
 {
 	u8 val;
@@ -225,10 +240,19 @@ static int max63xx_wdt_probe(struct platform_device *pdev)
 		return -EINVAL;
 	}
 
+	wdt->gpio_wdi = devm_gpiod_get(dev, NULL, GPIOD_FLAGS_BIT_DIR_OUT);
+	if (IS_ERR(wdt->gpio_wdi) && PTR_ERR(wdt->gpio_wdi) != -ENOENT)
+		return dev_err_probe(dev, PTR_ERR(wdt->gpio_wdi),
+				     "unable to request gpio: %ld\n",
+				     PTR_ERR(wdt->gpio_wdi));
+
 	err = max63xx_mmap_init(pdev, wdt);
 	if (err)
 		return err;
 
+	if (!IS_ERR(wdt->gpio_wdi))
+		wdt->ping = max63xx_gpio_ping;
+
 	platform_set_drvdata(pdev, &wdt->wdd);
 	watchdog_set_drvdata(&wdt->wdd, wdt);
 
-- 
2.20.1