u-boot/drivers/watchdog/gpio_wdt.c
Rasmus Villemoes 51443c9a49 watchdog: gpio_wdt: use __udelay() to avoid recursion
The udelay() function in lib/time.c contains a WATCHDOG_RESET()
call. The only reason this doesn't lead to a catastrophic infinite
recursion is due to the rate-limiting in wdt-uclass.c:

		if (time_after_eq(now, priv->next_reset)) {
			priv->next_reset = now + priv->reset_period;
			wdt_reset(dev);
		}

But this would fall apart if ->next_reset was updated after calling the
device's reset method.

This is needlessly fragile, and it's easy enough to avoid that
recursion in the first place by just using __udelay() directly.

Signed-off-by: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
Reviewed-by: Stefan Roese <sr@denx.de>
2022-09-27 12:25:40 +02:00

96 lines
1.9 KiB
C

// SPDX-License-Identifier: GPL-2.0+
#include <dm.h>
#include <dm/device_compat.h>
#include <wdt.h>
#include <asm/gpio.h>
#include <linux/delay.h>
enum {
HW_ALGO_TOGGLE,
HW_ALGO_LEVEL,
};
struct gpio_wdt_priv {
struct gpio_desc gpio;
unsigned int hw_algo;
bool always_running;
int state;
};
static int gpio_wdt_reset(struct udevice *dev)
{
struct gpio_wdt_priv *priv = dev_get_priv(dev);
switch (priv->hw_algo) {
case HW_ALGO_TOGGLE:
/* Toggle output pin */
priv->state = !priv->state;
dm_gpio_set_value(&priv->gpio, priv->state);
break;
case HW_ALGO_LEVEL:
/* Pulse */
dm_gpio_set_value(&priv->gpio, 1);
__udelay(1);
dm_gpio_set_value(&priv->gpio, 0);
break;
}
return 0;
}
static int gpio_wdt_start(struct udevice *dev, u64 timeout, ulong flags)
{
struct gpio_wdt_priv *priv = dev_get_priv(dev);
if (priv->always_running)
return 0;
return -ENOSYS;
}
static int dm_probe(struct udevice *dev)
{
struct gpio_wdt_priv *priv = dev_get_priv(dev);
int ret;
const char *algo = dev_read_string(dev, "hw_algo");
if (!algo)
return -EINVAL;
if (!strcmp(algo, "toggle"))
priv->hw_algo = HW_ALGO_TOGGLE;
else if (!strcmp(algo, "level"))
priv->hw_algo = HW_ALGO_LEVEL;
else
return -EINVAL;
priv->always_running = dev_read_bool(dev, "always-running");
ret = gpio_request_by_name(dev, "gpios", 0, &priv->gpio, GPIOD_IS_OUT);
if (ret < 0) {
dev_err(dev, "Request for wdt gpio failed: %d\n", ret);
return ret;
}
if (priv->always_running)
ret = gpio_wdt_reset(dev);
return ret;
}
static const struct wdt_ops gpio_wdt_ops = {
.start = gpio_wdt_start,
.reset = gpio_wdt_reset,
};
static const struct udevice_id gpio_wdt_ids[] = {
{ .compatible = "linux,wdt-gpio" },
{}
};
U_BOOT_DRIVER(wdt_gpio) = {
.name = "wdt_gpio",
.id = UCLASS_WDT,
.of_match = gpio_wdt_ids,
.ops = &gpio_wdt_ops,
.probe = dm_probe,
.priv_auto = sizeof(struct gpio_wdt_priv),
};