@@ -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>;
};
@@ -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");
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> --- .../devicetree/bindings/gpio/gpio-poweroff.txt | 20 ++++++++++-- drivers/power/reset/gpio-poweroff.c | 33 +++++++++----------- 2 files changed, 32 insertions(+), 21 deletions(-)