From b67da8b7975c5e98eb222c3b47617a46acee1f89 Mon Sep 17 00:00:00 2001 From: Nick Bulleid Date: Thu, 10 May 2018 21:57:02 +0100 Subject: [PATCH] Add ability to export gpio used by gpio-poweroff Signed-off-by: Nick Bulleid Added export feature to gpio-poweroff documentation Signed-off-by: Nick Bulleid --- .../bindings/power/reset/gpio-poweroff.txt | 42 +++++++++++++++++++ drivers/power/reset/gpio-poweroff.c | 9 ++++ 2 files changed, 51 insertions(+) create mode 100644 Documentation/devicetree/bindings/power/reset/gpio-poweroff.txt --- /dev/null +++ b/Documentation/devicetree/bindings/power/reset/gpio-poweroff.txt @@ -0,0 +1,42 @@ +Driver a GPIO line that can be used to turn the power off. + +The driver supports both level triggered and edge triggered power off. +At driver load time, the driver will request the given gpio line and +install a handler to power off the system. If the optional properties +'input' is not found, the GPIO line will be driven in the inactive +state. Otherwise its configured as an input. + +When the power-off handler is called, the gpio is configured as an +output, and drive active, so triggering a level triggered power off +condition. This will also cause an inactive->active edge condition, so +triggering positive edge triggered power off. After a delay of 100ms, +the GPIO is set to inactive, thus causing an active->inactive edge, +triggering negative edge triggered power off. After another 100ms +delay the GPIO is driver active again. If the power is still on and +the CPU still running after a 3000ms delay, a WARN_ON(1) is emitted. + +Required properties: +- compatible : should be "gpio-poweroff". +- gpios : The GPIO to set high/low, see "gpios property" in + Documentation/devicetree/bindings/gpio/gpio.txt. If the pin should be + low to power down the board set it to "Active Low", otherwise set + gpio to "Active High". + +Optional properties: +- input : Initially configure the GPIO line as an input. Only reconfigure + it to an output when the power-off handler is called. If this optional + property is not specified, the GPIO is initialized as an output in its + inactive state. +- active-delay-ms: Delay (default 100) to wait after driving gpio active +- inactive-delay-ms: Delay (default 100) to wait after driving gpio inactive +- timeout-ms: Time to wait before asserting a WARN_ON(1). If nothing is + specified, 3000 ms is used. +- export : Export the GPIO line to the sysfs system + +Examples: + +gpio-poweroff { + compatible = "gpio-poweroff"; + gpios = <&gpio 4 0>; + timeout-ms = <3000>; +}; --- a/drivers/power/reset/gpio-poweroff.c +++ b/drivers/power/reset/gpio-poweroff.c @@ -51,6 +51,7 @@ static int gpio_poweroff_probe(struct pl bool input = false; enum gpiod_flags flags; bool force = false; + bool export = false; /* If a pm_power_off function has already been added, leave it alone */ force = of_property_read_bool(pdev->dev.of_node, "force"); @@ -76,6 +77,12 @@ static int gpio_poweroff_probe(struct pl if (IS_ERR(reset_gpio)) return PTR_ERR(reset_gpio); + export = of_property_read_bool(pdev->dev.of_node, "export"); + if (export) { + gpiod_export(reset_gpio, false); + gpiod_export_link(&pdev->dev, "poweroff-gpio", reset_gpio); + } + pm_power_off = &gpio_poweroff_do_poweroff; return 0; } @@ -85,6 +92,8 @@ static int gpio_poweroff_remove(struct p if (pm_power_off == &gpio_poweroff_do_poweroff) pm_power_off = NULL; + gpiod_unexport(reset_gpio); + return 0; }