Power: gpio-poweroff: Fix documentation and gpio_is_valid
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>
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@ -1,4 +1,19 @@
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GPIO line that should be set high/low to power off a device
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Driver a GPIO line that can be used to turn the power off.
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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 pm_power_off handler. If the optional properties 'input' is
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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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When the pm_power_off is called, the gpio is configured as an output,
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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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Required properties:
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- compatible : should be "gpio-poweroff".
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@ -13,10 +28,9 @@ Optional properties:
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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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Examples:
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gpio-poweroff {
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compatible = "gpio-poweroff";
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gpios = <&gpio 4 0>; /* GPIO 4 Active Low */
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gpios = <&gpio 4 0>;
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};
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@ -29,15 +29,16 @@ static int gpio_active_low;
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static void gpio_poweroff_do_poweroff(void)
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{
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BUG_ON(gpio_num == -1);
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BUG_ON(!gpio_is_valid(gpio_num));
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/* drive it active */
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/* drive it active, also inactive->active edge */
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gpio_direction_output(gpio_num, !gpio_active_low);
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mdelay(100);
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/* rising edge or drive inactive */
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/* drive inactive, also active->inactive edge */
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gpio_set_value(gpio_num, gpio_active_low);
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mdelay(100);
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/* falling edge */
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/* drive it active, also inactive->active edge */
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gpio_set_value(gpio_num, !gpio_active_low);
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/* give it some time */
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@ -60,15 +61,12 @@ static int __devinit gpio_poweroff_probe(struct platform_device *pdev)
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}
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gpio_num = of_get_gpio_flags(pdev->dev.of_node, 0, &flags);
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if (gpio_num < 0) {
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pr_err("%s: Could not get GPIO configuration: %d",
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__func__, gpio_num);
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return -ENODEV;
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}
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if (!gpio_is_valid(gpio_num))
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return gpio_num;
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gpio_active_low = flags & OF_GPIO_ACTIVE_LOW;
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if (of_get_property(pdev->dev.of_node, "input", NULL))
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input = true;
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input = of_property_read_bool(pdev->dev.of_node, "input");
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ret = gpio_request(gpio_num, "poweroff-gpio");
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if (ret) {
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@ -98,8 +96,7 @@ err:
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static int __devexit gpio_poweroff_remove(struct platform_device *pdev)
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{
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if (gpio_num != -1)
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gpio_free(gpio_num);
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gpio_free(gpio_num);
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if (pm_power_off == &gpio_poweroff_do_poweroff)
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pm_power_off = NULL;
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@ -115,15 +112,15 @@ static struct platform_driver gpio_poweroff_driver = {
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.probe = gpio_poweroff_probe,
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.remove = __devexit_p(gpio_poweroff_remove),
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.driver = {
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.name = "poweroff-gpio",
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.owner = THIS_MODULE,
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.of_match_table = of_gpio_poweroff_match,
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},
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.name = "poweroff-gpio",
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.owner = THIS_MODULE,
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.of_match_table = of_gpio_poweroff_match,
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},
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};
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module_platform_driver(gpio_poweroff_driver);
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MODULE_AUTHOR("Jamie Lentin <jm@lentin.co.uk>");
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MODULE_DESCRIPTION("GPIO poweroff driver");
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MODULE_LICENSE("GPL");
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MODULE_LICENSE("GPL v2");
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MODULE_ALIAS("platform:poweroff-gpio");
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