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Power: gpio-poweroff: Fix documentation and gpio_is_valid

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Improve the documentation to clarify level vs edge triggered power off.
Improve the comments for level vs edge triggered power off.
Make use of gpio_is_valid().

Reported-by: Stephen Warren <swarren@wwwdotorg.org>
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Jason Cooper <jason@lakedaemon.net>
This commit is contained in:
Andrew Lunn 2013-01-06 11:10:35 +01:00 committed by Jason Cooper
parent 53dfa8e4aa
commit 5343527bbf
2 changed files with 32 additions and 21 deletions
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20
Documentation/devicetree/bindings/gpio/gpio-poweroff.txt
View file

@ -1,4 +1,19 @@
GPIO line that should be set high/low to power off a device
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 pm_power_off handler. 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 pm_power_off 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".
@ -13,10 +28,9 @@ Optional properties:
property is not specified, the GPIO is initialized as an output in its
inactive state.
Examples:
gpio-poweroff {
compatible = "gpio-poweroff";
gpios = <&gpio 4 0>; /* GPIO 4 Active Low */
gpios = <&gpio 4 0>;
};

33
drivers/power/reset/gpio-poweroff.c
View file

@ -29,15 +29,16 @@ static int gpio_active_low;
static void gpio_poweroff_do_poweroff(void)
{
BUG_ON(gpio_num == -1);
BUG_ON(!gpio_is_valid(gpio_num));
/* drive it active */
/* drive it active, also inactive->active edge */
gpio_direction_output(gpio_num, !gpio_active_low);
mdelay(100);
/* rising edge or drive inactive */
/* drive inactive, also active->inactive edge */
gpio_set_value(gpio_num, gpio_active_low);
mdelay(100);
/* falling edge */
/* drive it active, also inactive->active edge */
gpio_set_value(gpio_num, !gpio_active_low);
/* give it some time */
@ -60,15 +61,12 @@ static int __devinit gpio_poweroff_probe(struct platform_device *pdev)
}
gpio_num = of_get_gpio_flags(pdev->dev.of_node, 0, &flags);
if (gpio_num < 0) {
pr_err("%s: Could not get GPIO configuration: %d",
__func__, gpio_num);
return -ENODEV;
}
if (!gpio_is_valid(gpio_num))
return gpio_num;
gpio_active_low = flags & OF_GPIO_ACTIVE_LOW;
if (of_get_property(pdev->dev.of_node, "input", NULL))
input = true;
input = of_property_read_bool(pdev->dev.of_node, "input");
ret = gpio_request(gpio_num, "poweroff-gpio");
if (ret) {
@ -98,8 +96,7 @@ err:
static int __devexit gpio_poweroff_remove(struct platform_device *pdev)
{
if (gpio_num != -1)
gpio_free(gpio_num);
gpio_free(gpio_num);
if (pm_power_off == &gpio_poweroff_do_poweroff)
pm_power_off = NULL;
@ -115,15 +112,15 @@ static struct platform_driver gpio_poweroff_driver = {
.probe = gpio_poweroff_probe,
.remove = __devexit_p(gpio_poweroff_remove),
.driver = {
.name = "poweroff-gpio",
.owner = THIS_MODULE,
.of_match_table = of_gpio_poweroff_match,
},
.name = "poweroff-gpio",
.owner = THIS_MODULE,
.of_match_table = of_gpio_poweroff_match,
},
};
module_platform_driver(gpio_poweroff_driver);
MODULE_AUTHOR("Jamie Lentin <jm@lentin.co.uk>");
MODULE_DESCRIPTION("GPIO poweroff driver");
MODULE_LICENSE("GPL");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:poweroff-gpio");