1Drive a GPIO line that can be used to restart the system from a restart 2handler. 3 4This binding supports level and edge triggered reset. At driver load 5time, the driver will request the given gpio line and install a restart 6handler. If the optional properties 'open-source' is not found, the GPIO line 7will be driven in the inactive state. Otherwise its not driven until 8the restart is initiated. 9 10When the system is restarted, the restart handler will be invoked in 11priority order. The gpio is configured as an output, and driven active, 12triggering a level triggered reset condition. This will also cause an 13inactive->active edge condition, triggering positive edge triggered 14reset. After a delay specified by active-delay, the GPIO is set to 15inactive, thus causing an active->inactive edge, triggering negative edge 16triggered reset. After a delay specified by inactive-delay, the GPIO 17is driven active again. After a delay specified by wait-delay, the 18restart handler completes allowing other restart handlers to be attempted. 19 20Required properties: 21- compatible : should be "gpio-restart". 22- gpios : The GPIO to set high/low, see "gpios property" in 23 Documentation/devicetree/bindings/gpio/gpio.txt. If the pin should be 24 low to reset the board set it to "Active Low", otherwise set 25 gpio to "Active High". 26 27Optional properties: 28- open-source : Treat the GPIO as being open source and defer driving 29 it to when the restart is initiated. If this optional property is not 30 specified, the GPIO is initialized as an output in its inactive state. 31- priority : A priority ranging from 0 to 255 (default 128) according to 32 the following guidelines: 33 0: Restart handler of last resort, with limited restart 34 capabilities 35 128: Default restart handler; use if no other restart handler is 36 expected to be available, and/or if restart functionality is 37 sufficient to restart the entire system 38 255: Highest priority restart handler, will preempt all other 39 restart handlers 40- active-delay: Delay (default 100) to wait after driving gpio active [ms] 41- inactive-delay: Delay (default 100) to wait after driving gpio inactive [ms] 42- wait-delay: Delay (default 3000) to wait after completing restart 43 sequence [ms] 44 45Examples: 46 47gpio-restart { 48 compatible = "gpio-restart"; 49 gpios = <&gpio 4 0>; 50 priority = <128>; 51 active-delay = <100>; 52 inactive-delay = <100>; 53 wait-delay = <3000>; 54}; 55