[1/3] gpio: Add simple poweroff-gpio driver

Message ID	1352650891-18356-2-git-send-email-andrew@lunn.ch (mailing list archive)
State	New, archived
Headers	show Return-Path: <linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org> From: Andrew Lunn <andrew@lunn.ch> To: linus.walleij@linaro.org Subject: [PATCH 1/3] gpio: Add simple poweroff-gpio driver Date: Sun, 11 Nov 2012 17:21:29 +0100 Message-Id: <1352650891-18356-2-git-send-email-andrew@lunn.ch> In-Reply-To: <1352650891-18356-1-git-send-email-andrew@lunn.ch> References: <1352650891-18356-1-git-send-email-andrew@lunn.ch> summary: Content analysis details: (-2.6 points) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 SPF_HELO_PASS SPF: HELO matches SPF record -0.0 SPF_PASS SPF: sender matches SPF record -0.7 RP_MATCHES_RCVD Envelope sender domain matches handover relay domain -1.9 BAYES_00 BODY: Bayes spam probability is 0 to 1% [score: 0.0000] Cc: Andrew Lunn <andrew@lunn.ch>, Jason Cooper <jason@lakedaemon.net>, devicetree-discuss@lists.ozlabs.org, jm@lentin.co.uk, linux-arm-kernel@lists.infradead.org, gmbnomis@gmail.com Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: linux-arm-kernel-bounces@lists.infradead.org Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org

diff --git a/Documentation/devicetree/bindings/gpio/gpio-poweroff.txt b/Documentation/devicetree/bindings/gpio/gpio-poweroff.txt new file mode 100644 index 0000000..558cdf3 --- /dev/null +++ b/Documentation/devicetree/bindings/gpio/gpio-poweroff.txt @@ -0,0 +1,22 @@ +GPIO line that should be set high/low to power off a device + +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 pm_power_off function is called. If this optional + 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 */ +}; diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig index d055cee..5ec1714 100644 --- a/drivers/gpio/Kconfig +++ b/drivers/gpio/Kconfig @@ -75,6 +75,16 @@ config GPIO_SYSFS Kernel drivers may also request that a particular GPIO be exported to userspace; this can be useful when debugging. +config GPIO_POWEROFF + tristate "GPIO power-off driver" + depends on OF_GPIO + help + This driver supports turning off your device via a GPIO line. + If your device needs a GPIO high/low to power down, say Y and + create a binding in your devicetree. + + If unsure, say N + config GPIO_GENERIC tristate diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile index 9aeed67..a8efda3 100644 --- a/drivers/gpio/Makefile +++ b/drivers/gpio/Makefile @@ -5,6 +5,8 @@ ccflags-$(CONFIG_DEBUG_GPIO) += -DDEBUG obj-$(CONFIG_GPIOLIB) += gpiolib.o devres.o obj-$(CONFIG_OF_GPIO) += gpiolib-of.o +obj-$(CONFIG_GPIO_POWEROFF) += gpio-poweroff.o + # Device drivers. Generally keep list sorted alphabetically obj-$(CONFIG_GPIO_GENERIC) += gpio-generic.o diff --git a/drivers/gpio/gpio-poweroff.c b/drivers/gpio/gpio-poweroff.c new file mode 100644 index 0000000..101ad57 --- /dev/null +++ b/drivers/gpio/gpio-poweroff.c @@ -0,0 +1,129 @@ +/* + * Toggles a GPIO pin to power down a device + * + * Jamie Lentin <jm@lentin.co.uk> + * Andrew Lunn <andrew@lunn.ch> + * + * Copyright (C) 2012 Jamie Lentin + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + */ +#include <linux/kernel.h> +#include <linux/init.h> +#include <linux/delay.h> +#include <linux/platform_device.h> +#include <linux/gpio.h> +#include <linux/of_platform.h> +#include <linux/of_gpio.h> +#include <linux/module.h> + +/* + * Hold configuration here, cannot be more than one instance of the driver + * since pm_power_off itself is global. + */ +static int gpio_num = -1; +static int gpio_active_low; + +static void gpio_poweroff_do_poweroff(void) +{ + BUG_ON(gpio_num == -1); + + /* drive it active */ + gpio_direction_output(gpio_num, !gpio_active_low); + mdelay(100); + /* rising edge or drive inactive */ + gpio_set_value(gpio_num, gpio_active_low); + mdelay(100); + /* falling edge */ + gpio_set_value(gpio_num, !gpio_active_low); + + /* give it some time */ + mdelay(100); + + WARN_ON(1); +} + +static int __devinit gpio_poweroff_probe(struct platform_device *pdev) +{ + enum of_gpio_flags flags; + bool input = false; + int ret; + + /* If a pm_power_off function has already been added, leave it alone */ + if (pm_power_off != NULL) { + pr_err("%s: pm_power_off function already registered", + __func__); + return -EBUSY; + } + + 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; + } + gpio_active_low = flags & OF_GPIO_ACTIVE_LOW; + + if (of_get_property(pdev->dev.of_node, "input", NULL)) + input = true; + + ret = gpio_request(gpio_num, "poweroff-gpio"); + if (ret) { + pr_err("%s: Could not get GPIO %d", __func__, gpio_num); + return ret; + } + if (input) { + if (gpio_direction_input(gpio_num)) { + pr_err("Could not set direction of GPIO %d to input", + gpio_num); + goto err; + } + } else { + if (gpio_direction_output(gpio_num, gpio_active_low)) { + pr_err("Could not set direction of GPIO %d", gpio_num); + goto err; + } + } + + pm_power_off = &gpio_poweroff_do_poweroff; + return 0; + +err: + gpio_free(gpio_num); + return -ENODEV; +} + +static int __devexit gpio_poweroff_remove(struct platform_device *pdev) +{ + if (gpio_num != -1) + gpio_free(gpio_num); + if (pm_power_off == &gpio_poweroff_do_poweroff) + pm_power_off = NULL; + + return 0; +} + +static const struct of_device_id of_gpio_poweroff_match[] = { + { .compatible = "gpio-poweroff", }, + {}, +}; + +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, + }, +}; + +module_platform_driver(gpio_poweroff_driver); + +MODULE_AUTHOR("Jamie Lentin <jm@lentin.co.uk>"); +MODULE_DESCRIPTION("GPIO poweroff driver"); +MODULE_LICENSE("GPL"); +MODULE_ALIAS("platform:poweroff-gpio");

[1/3] gpio: Add simple poweroff-gpio driver

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