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1fc45d6483
A common external watchdog circuit is kept alive by triggering a short pulse on the reset pin. This patch adds support for this use case, while making the algorithm configurable in the devicetree. The "linux,wdt-gpio" driver being modified is based off the equivalent driver in the Linux kernel, which provides support for this algorithm. This patch brings parity to this driver, and is kept aligned with the functionality and devicetree configuration in the kernel. It should be noted that this adds a required property named 'hw_algo' to the devicetree binding, following suit with the kernel. I'm happy to make this backward-compatible if preferred. Signed-off-by: Paul Doelle <paaull.git@gmail.com> Reviewed-by: Stefan Roese <sr@denx.de>
96 lines
1.9 KiB
C
96 lines
1.9 KiB
C
// SPDX-License-Identifier: GPL-2.0+
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#include <dm.h>
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#include <dm/device_compat.h>
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#include <wdt.h>
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#include <asm/gpio.h>
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#include <linux/delay.h>
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enum {
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HW_ALGO_TOGGLE,
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HW_ALGO_LEVEL,
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};
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struct gpio_wdt_priv {
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struct gpio_desc gpio;
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unsigned int hw_algo;
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bool always_running;
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int state;
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};
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static int gpio_wdt_reset(struct udevice *dev)
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{
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struct gpio_wdt_priv *priv = dev_get_priv(dev);
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switch (priv->hw_algo) {
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case HW_ALGO_TOGGLE:
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/* Toggle output pin */
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priv->state = !priv->state;
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dm_gpio_set_value(&priv->gpio, priv->state);
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break;
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case HW_ALGO_LEVEL:
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/* Pulse */
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dm_gpio_set_value(&priv->gpio, 1);
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udelay(1);
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dm_gpio_set_value(&priv->gpio, 0);
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break;
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}
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return 0;
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}
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static int gpio_wdt_start(struct udevice *dev, u64 timeout, ulong flags)
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{
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struct gpio_wdt_priv *priv = dev_get_priv(dev);
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if (priv->always_running)
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return 0;
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return -ENOSYS;
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}
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static int dm_probe(struct udevice *dev)
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{
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struct gpio_wdt_priv *priv = dev_get_priv(dev);
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int ret;
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const char *algo = dev_read_string(dev, "hw_algo");
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if (!algo)
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return -EINVAL;
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if (!strcmp(algo, "toggle"))
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priv->hw_algo = HW_ALGO_TOGGLE;
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else if (!strcmp(algo, "level"))
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priv->hw_algo = HW_ALGO_LEVEL;
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else
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return -EINVAL;
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priv->always_running = dev_read_bool(dev, "always-running");
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ret = gpio_request_by_name(dev, "gpios", 0, &priv->gpio, GPIOD_IS_OUT);
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if (ret < 0) {
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dev_err(dev, "Request for wdt gpio failed: %d\n", ret);
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return ret;
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}
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if (priv->always_running)
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ret = gpio_wdt_reset(dev);
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return ret;
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}
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static const struct wdt_ops gpio_wdt_ops = {
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.start = gpio_wdt_start,
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.reset = gpio_wdt_reset,
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};
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static const struct udevice_id gpio_wdt_ids[] = {
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{ .compatible = "linux,wdt-gpio" },
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{}
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};
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U_BOOT_DRIVER(wdt_gpio) = {
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.name = "wdt_gpio",
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.id = UCLASS_WDT,
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.of_match = gpio_wdt_ids,
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.ops = &gpio_wdt_ops,
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.probe = dm_probe,
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.priv_auto = sizeof(struct gpio_wdt_priv),
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};
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