1 files changed, 143 insertions, 0 deletions
diff --git a/drivers/watchdog/gpio_wdt.c b/drivers/watchdog/gpio_wdt.c
new file mode 100644
index 0000000000..5fa98f87c6
--- /dev/null
+++ b/drivers/watchdog/gpio_wdt.c
@@ -0,0 +1,143 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Driver for watchdog device controlled through GPIO-line
+ *
+ * Author: 2013, Alexander Shiyan <shc_work@mail.ru>
+ */
+
+#include <common.h>
+#include <driver.h>
+#include <watchdog.h>
+#include <superio.h>
+#include <linux/gpio/consumer.h>
+
+enum {
+	HW_ALGO_TOGGLE,
+	HW_ALGO_LEVEL,
+};
+
+struct gpio_wdt_priv {
+	struct gpio_desc *gpiod;
+	bool		state;
+	bool		started;
+	unsigned int	hw_algo;
+	struct watchdog	wdd;
+};
+
+static inline struct gpio_wdt_priv *to_gpio_wdt_priv(struct watchdog *wdd)
+{
+	return container_of(wdd, struct gpio_wdt_priv, wdd);
+}
+
+static void gpio_wdt_disable(struct gpio_wdt_priv *priv)
+{
+	/* Eternal ping */
+	gpiod_set_value(priv->gpiod, 1);
+
+	/* Put GPIO back to tristate */
+	if (priv->hw_algo == HW_ALGO_TOGGLE)
+		gpiod_direction_input(priv->gpiod);
+
+	priv->started = false;
+}
+
+static void gpio_wdt_ping(struct gpio_wdt_priv *priv)
+{
+	switch (priv->hw_algo) {
+	case HW_ALGO_TOGGLE:
+		/* Toggle output pin */
+		priv->state = !priv->state;
+		gpiod_set_value(priv->gpiod, priv->state);
+		break;
+	case HW_ALGO_LEVEL:
+		/* Pulse */
+		gpiod_set_value(priv->gpiod, true);
+		udelay(1);
+		gpiod_set_value(priv->gpiod, false);
+		break;
+	}
+}
+
+static void gpio_wdt_start(struct gpio_wdt_priv *priv)
+{
+	priv->state = false;
+	gpiod_direction_output(priv->gpiod, priv->state);
+	priv->started = true;
+}
+
+static int gpio_wdt_set_timeout(struct watchdog *wdd, unsigned int new_timeout)
+{
+	struct gpio_wdt_priv *priv = to_gpio_wdt_priv(wdd);
+
+	if (!new_timeout) {
+		gpio_wdt_disable(priv);
+		return 0;
+	}
+
+	if (!priv->started)
+		gpio_wdt_start(priv);
+
+	gpio_wdt_ping(priv);
+	return 0;
+}
+
+static int gpio_wdt_probe(struct device *dev)
+{
+	struct device_node *np = dev->of_node;
+	struct gpio_wdt_priv *priv;
+	enum gpiod_flags gflags;
+	unsigned int hw_margin;
+	const char *algo;
+	int ret;
+
+	priv = xzalloc(sizeof(*priv));
+
+	ret = of_property_read_u32(np, "hw_margin_ms", &hw_margin);
+	if (ret)
+		return ret;
+
+	/* Autoping is fixed at one ping every 500 ms. Round it up to a second */
+	if (hw_margin < 1000)
+		return -EINVAL;
+
+	ret = of_property_read_string(np, "hw_algo", &algo);
+	if (ret)
+		return ret;
+	if (!strcmp(algo, "toggle")) {
+		priv->hw_algo = HW_ALGO_TOGGLE;
+		gflags = GPIOD_IN;
+	} else if (!strcmp(algo, "level")) {
+		priv->hw_algo = HW_ALGO_LEVEL;
+		gflags = GPIOD_OUT_LOW;
+	} else {
+		return -EINVAL;
+	}
+
+	priv->gpiod = gpiod_get(dev, NULL, gflags);
+	if (IS_ERR(priv->gpiod))
+		return PTR_ERR(priv->gpiod);
+
+	priv->wdd.hwdev		= dev;
+	priv->wdd.timeout_max	= hw_margin / 1000;
+	priv->wdd.priority	= 129;
+	priv->wdd.set_timeout	= gpio_wdt_set_timeout;
+
+	return watchdog_register(&priv->wdd);
+}
+
+static const struct of_device_id gpio_wdt_dt_ids[] = {
+	{ .compatible = "linux,wdt-gpio", },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, gpio_wdt_dt_ids);
+
+static struct driver gpio_wdt_driver = {
+	.name		= "gpio-wdt",
+	.of_compatible	= gpio_wdt_dt_ids,
+	.probe	= gpio_wdt_probe,
+};
+device_platform_driver(gpio_wdt_driver);
+
+MODULE_AUTHOR("Alexander Shiyan <shc_work@mail.ru>");
+MODULE_DESCRIPTION("GPIO Watchdog");
+MODULE_LICENSE("GPL");