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watchdog: gpio_wdt: add support for stoppable devices

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Back when I added this driver in commit 2ac8490412, I wrote

    The corresponding linux driver apparently has support for some
    watchdog circuits which can be disabled by tri-stating the gpio, but I
    have never actually encountered such a chip in the wild;

That has changed now; I have a board with just such a watchdog on my
desk currently. Add support for that.

- For a hw_algo="toggle" device, the gpio is requested as output if the
  always-running flag is set, otherwise as input.

- The ->start() method is updated to change the direction to output when
  required (i.e. it is not always-running).

- The ->stop() method is implemented, but of course reports failure if
  always-running.

As I still haven't met any hw_algo="level" devices, I'm not entirely
sure how they fit in, but I'm borrowing logic from the corresponding
linux driver:

- In ->probe(), such devices always request the gpio as GPIOD_IS_OUT.

- In ->stop(), the linux driver has an "eternal ping" comment and sets
  the gpio to (logic) high.

Stefan:
Added necessary changes in test/dm/wdt.c to fix CI build breakage, as
suggested by Rasmus.

Signed-off-by: Rasmus Villemoes <ravi@prevas.dk>
Reviewed-by: Stefan Roese <sr@denx.de>
This commit is contained in:
Rasmus Villemoes 2024-10-02 21:23:23 +02:00 • committed by Stefan Roese
parent 392ff1449f
commit 7f3d53c8bf
2 changed files with 26 additions and 5 deletions
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27
drivers/watchdog/gpio_wdt.c
View file

@ -45,14 +45,32 @@ static int gpio_wdt_start(struct udevice *dev, u64 timeout, ulong flags)
if (priv->always_running)
return 0;
return -ENOSYS;
dm_gpio_set_dir_flags(&priv->gpio, GPIOD_IS_OUT);
gpio_wdt_reset(dev);
return 0;
}
static int gpio_wdt_stop(struct udevice *dev)
{
struct gpio_wdt_priv *priv = dev_get_priv(dev);
if (priv->always_running)
return -EOPNOTSUPP;
if (priv->hw_algo == HW_ALGO_TOGGLE)
dm_gpio_set_dir_flags(&priv->gpio, GPIOD_IS_IN);
else
dm_gpio_set_value(&priv->gpio, 1);
return 0;
}
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");
int ret, flags;
if (!algo)
return -EINVAL;
@ -64,7 +82,9 @@ static int dm_probe(struct udevice *dev)
return -EINVAL;
priv->always_running = dev_read_bool(dev, "always-running");
ret = gpio_request_by_name(dev, "gpios", 0, &priv->gpio, GPIOD_IS_OUT);
flags = priv->always_running || priv->hw_algo == HW_ALGO_LEVEL ?
GPIOD_IS_OUT : GPIOD_IS_IN;
ret = gpio_request_by_name(dev, "gpios", 0, &priv->gpio, flags);
if (ret < 0) {
dev_err(dev, "Request for wdt gpio failed: %d\n", ret);
return ret;
@ -78,6 +98,7 @@ static int dm_probe(struct udevice *dev)
static const struct wdt_ops gpio_wdt_ops = {
.start = gpio_wdt_start,
.stop = gpio_wdt_stop,
.reset = gpio_wdt_reset,
};

4
test/dm/wdt.c
View file

@ -71,7 +71,7 @@ static int dm_test_wdt_gpio_toggle(struct unit_test_state *uts)
ut_assertok(wdt_reset(wdt));
ut_asserteq(val, sandbox_gpio_get_value(gpio, offset));
ut_asserteq(-ENOSYS, wdt_stop(wdt));
ut_asserteq(-EOPNOTSUPP, wdt_stop(wdt));
return 0;
}
@ -103,7 +103,7 @@ static int dm_test_wdt_gpio_level(struct unit_test_state *uts)
ut_assertok(wdt_reset(wdt));
ut_asserteq(val, sandbox_gpio_get_value(gpio, offset));
ut_asserteq(-ENOSYS, wdt_stop(wdt));
ut_asserteq(-EOPNOTSUPP, wdt_stop(wdt));
return 0;
}