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From b67da8b7975c5e98eb222c3b47617a46acee1f89 Mon Sep 17 00:00:00 2001
From: Nick Bulleid <nedbulleid@fastmail.com>
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 <nedbulleid@fastmail.com>
Added export feature to gpio-poweroff documentation
Signed-off-by: Nick Bulleid <nedbulleid@fastmail.com>
---
.../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;
}
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