diff options
Diffstat (limited to 'drivers/power/reset/gpio-poweroff.c')
| -rw-r--r-- | drivers/power/reset/gpio-poweroff.c | 109 |
1 files changed, 109 insertions, 0 deletions
diff --git a/drivers/power/reset/gpio-poweroff.c b/drivers/power/reset/gpio-poweroff.c new file mode 100644 index 000000000..1c5af2fef --- /dev/null +++ b/drivers/power/reset/gpio-poweroff.c @@ -0,0 +1,109 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * 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 + */ +#include <linux/kernel.h> +#include <linux/init.h> +#include <linux/delay.h> +#include <linux/platform_device.h> +#include <linux/gpio/consumer.h> +#include <linux/of_platform.h> +#include <linux/module.h> + +#define DEFAULT_TIMEOUT_MS 3000 +/* + * Hold configuration here, cannot be more than one instance of the driver + * since pm_power_off itself is global. + */ +static struct gpio_desc *reset_gpio; +static u32 timeout = DEFAULT_TIMEOUT_MS; +static u32 active_delay = 100; +static u32 inactive_delay = 100; + +static void gpio_poweroff_do_poweroff(void) +{ + BUG_ON(!reset_gpio); + + /* drive it active, also inactive->active edge */ + gpiod_direction_output(reset_gpio, 1); + mdelay(active_delay); + + /* drive inactive, also active->inactive edge */ + gpiod_set_value_cansleep(reset_gpio, 0); + mdelay(inactive_delay); + + /* drive it active, also inactive->active edge */ + gpiod_set_value_cansleep(reset_gpio, 1); + + /* give it some time */ + mdelay(timeout); + + WARN_ON(1); +} + +static int gpio_poweroff_probe(struct platform_device *pdev) +{ + bool input = false; + enum gpiod_flags flags; + + /* If a pm_power_off function has already been added, leave it alone */ + if (pm_power_off != NULL) { + dev_err(&pdev->dev, + "%s: pm_power_off function already registered\n", + __func__); + return -EBUSY; + } + + input = device_property_read_bool(&pdev->dev, "input"); + if (input) + flags = GPIOD_IN; + else + flags = GPIOD_OUT_LOW; + + device_property_read_u32(&pdev->dev, "active-delay-ms", &active_delay); + device_property_read_u32(&pdev->dev, "inactive-delay-ms", + &inactive_delay); + device_property_read_u32(&pdev->dev, "timeout-ms", &timeout); + + reset_gpio = devm_gpiod_get(&pdev->dev, NULL, flags); + if (IS_ERR(reset_gpio)) + return PTR_ERR(reset_gpio); + + pm_power_off = &gpio_poweroff_do_poweroff; + return 0; +} + +static int gpio_poweroff_remove(struct platform_device *pdev) +{ + 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", }, + {}, +}; +MODULE_DEVICE_TABLE(of, of_gpio_poweroff_match); + +static struct platform_driver gpio_poweroff_driver = { + .probe = gpio_poweroff_probe, + .remove = gpio_poweroff_remove, + .driver = { + .name = "poweroff-gpio", + .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 v2"); +MODULE_ALIAS("platform:poweroff-gpio"); |