GPIO WATCHDOG

sayi — Thu, 09 Feb 2017 17:49:14 GMT

Hi,

Could you please advise how to configure dts file to enable GPIO based hardware watchdog in Linux?

Thanks,

Re: GPIO WATCHDOG

Carlos_Musich — Tue, 21 Feb 2017 20:55:05 GMT

Hi Free Samples,

Required:

- compatible: Should contain "linux,wdt-gpio".

- gpios: From common gpio binding; gpio connection to WDT reset pin.

- hw_algo: The algorithm used by the driver. Should be one of the following values:
- toggle: Either a high-to-low or a low-to-high transition clears the WDT counter. The watchdog timer is disabled when GPIO is left floating or connected to a three-state buffer.
- level: Low or high level starts counting WDT timeout, the opposite level disables the WDT. Active level is determined by the GPIO flags.

- hw_margin_ms: Maximum time to reset watchdog circuit (milliseconds).

Optional:
- always-running: If the watchdog timer cannot be disabled, add this flag to have the driver keep toggling the signal without a client. It will only cease to toggle the signal when the device is open and the timeout elapsed.

Example:
   watchdog: watchdog {
       compatible = "linux,wdt-gpio";
       gpios = <&gpio3 9 GPIO_ACTIVE_LOW>;
       hw_algo = "toggle";
       hw_margin_ms = <1600>;
   };

For the driver you can take a look to following reference:

Linux/drivers/watchdog/gpio_wdt.c - Linux Cross Reference - Free Electrons

Regards,
Carlos

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