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93 lines
3.5 KiB
Diff
93 lines
3.5 KiB
Diff
From bd9e1d253836bcd8215c97f03faaa6c30233b313 Mon Sep 17 00:00:00 2001
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From: Nick Bulleid <nedbulleid@fastmail.com>
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Date: Thu, 10 May 2018 21:57:02 +0100
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Subject: [PATCH] Add ability to export gpio used by gpio-poweroff
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Signed-off-by: Nick Bulleid <nedbulleid@fastmail.com>
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Added export feature to gpio-poweroff documentation
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Signed-off-by: Nick Bulleid <nedbulleid@fastmail.com>
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---
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.../bindings/power/reset/gpio-poweroff.txt | 42 +++++++++++++++++++
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drivers/power/reset/gpio-poweroff.c | 9 ++++
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2 files changed, 51 insertions(+)
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create mode 100644 Documentation/devicetree/bindings/power/reset/gpio-poweroff.txt
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--- /dev/null
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+++ b/Documentation/devicetree/bindings/power/reset/gpio-poweroff.txt
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@@ -0,0 +1,42 @@
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+Driver a GPIO line that can be used to turn the power off.
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+
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+The driver supports both level triggered and edge triggered power off.
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+At driver load time, the driver will request the given gpio line and
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+install a handler to power off the system. If the optional properties
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+'input' is not found, the GPIO line will be driven in the inactive
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+state. Otherwise its configured as an input.
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+
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+When the power-off handler is called, the gpio is configured as an
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+output, and drive active, so triggering a level triggered power off
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+condition. This will also cause an inactive->active edge condition, so
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+triggering positive edge triggered power off. After a delay of 100ms,
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+the GPIO is set to inactive, thus causing an active->inactive edge,
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+triggering negative edge triggered power off. After another 100ms
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+delay the GPIO is driver active again. If the power is still on and
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+the CPU still running after a 3000ms delay, a WARN_ON(1) is emitted.
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+
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+Required properties:
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+- compatible : should be "gpio-poweroff".
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+- gpios : The GPIO to set high/low, see "gpios property" in
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+ Documentation/devicetree/bindings/gpio/gpio.txt. If the pin should be
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+ low to power down the board set it to "Active Low", otherwise set
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+ gpio to "Active High".
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+
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+Optional properties:
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+- input : Initially configure the GPIO line as an input. Only reconfigure
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+ it to an output when the power-off handler is called. If this optional
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+ property is not specified, the GPIO is initialized as an output in its
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+ inactive state.
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+- active-delay-ms: Delay (default 100) to wait after driving gpio active
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+- inactive-delay-ms: Delay (default 100) to wait after driving gpio inactive
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+- timeout-ms: Time to wait before asserting a WARN_ON(1). If nothing is
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+ specified, 3000 ms is used.
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+- export : Export the GPIO line to the sysfs system
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+
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+Examples:
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+
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+gpio-poweroff {
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+ compatible = "gpio-poweroff";
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+ gpios = <&gpio 4 0>;
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+ timeout-ms = <3000>;
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+};
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--- a/drivers/power/reset/gpio-poweroff.c
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+++ b/drivers/power/reset/gpio-poweroff.c
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@@ -51,6 +51,7 @@ static int gpio_poweroff_probe(struct pl
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bool input = false;
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enum gpiod_flags flags;
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bool force = false;
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+ bool export = false;
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/* If a pm_power_off function has already been added, leave it alone */
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force = of_property_read_bool(pdev->dev.of_node, "force");
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@@ -76,6 +77,12 @@ static int gpio_poweroff_probe(struct pl
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if (IS_ERR(reset_gpio))
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return PTR_ERR(reset_gpio);
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+ export = of_property_read_bool(pdev->dev.of_node, "export");
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+ if (export) {
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+ gpiod_export(reset_gpio, false);
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+ gpiod_export_link(&pdev->dev, "poweroff-gpio", reset_gpio);
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+ }
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+
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pm_power_off = &gpio_poweroff_do_poweroff;
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return 0;
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}
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@@ -85,6 +92,8 @@ static int gpio_poweroff_remove(struct p
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if (pm_power_off == &gpio_poweroff_do_poweroff)
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pm_power_off = NULL;
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+ gpiod_unexport(reset_gpio);
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+
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return 0;
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}
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