Re: [PATCH] watchdog: gpio_wdt: add support for stoppable devices

Hi Rasmus,

On 10/2/24 21:23, Rasmus Villemoes wrote:

Back when I added this driver in commit 2ac8490412c9, 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.

Signed-off-by: Rasmus Villemoes ravi@prevas.dk

While running a CI build, I'm seeing some sandbox failures, most likely related to this change here:

https://dev.azure.com/sr0718/u-boot/_build/results?buildId=375&view=logs...

Could you please take a look at this?

Thanks, Stefan

---

drivers/watchdog/gpio_wdt.c | 27 ++++++++++++++++++++++++--- 1 file changed, 24 insertions(+), 3 deletions(-)

diff --git a/drivers/watchdog/gpio_wdt.c b/drivers/watchdog/gpio_wdt.c index 2920c2c751f..e889861e917 100644 --- a/drivers/watchdog/gpio_wdt.c +++ b/drivers/watchdog/gpio_wdt.c @@ -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, };

Viele Grüße, Stefan Roese