diff options
Diffstat (limited to 'drivers/reset/gpio-reset.c')
| -rw-r--r-- | drivers/reset/gpio-reset.c | 217 |
1 files changed, 217 insertions, 0 deletions
diff --git a/drivers/reset/gpio-reset.c b/drivers/reset/gpio-reset.c new file mode 100644 index 000000000000..cfd3fe02611b --- /dev/null +++ b/drivers/reset/gpio-reset.c @@ -0,0 +1,217 @@ +/* + * GPIO Reset Controller driver + * + * Copyright 2013 Philipp Zabel, Pengutronix + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + */ +#include <linux/delay.h> +#include <linux/err.h> +#include <linux/gpio.h> +#include <linux/module.h> +#include <linux/of_gpio.h> +#include <linux/platform_device.h> +#include <linux/pinctrl/consumer.h> +#include <linux/reset-controller.h> + +struct gpio_reset_data { + struct reset_controller_dev rcdev; + unsigned int gpio; + bool active_low; + s32 delay_us; + s32 post_delay_ms; +}; + +static void gpio_reset_set(struct reset_controller_dev *rcdev, int asserted) +{ + struct gpio_reset_data *drvdata = container_of(rcdev, + struct gpio_reset_data, rcdev); + int value = asserted; + + if (drvdata->active_low) + value = !value; + + gpio_set_value_cansleep(drvdata->gpio, value); +} + +static int gpio_reset(struct reset_controller_dev *rcdev, unsigned long id) +{ + struct gpio_reset_data *drvdata = container_of(rcdev, + struct gpio_reset_data, rcdev); + + if (drvdata->delay_us < 0) + return -ENOSYS; + + gpio_reset_set(rcdev, 1); + udelay(drvdata->delay_us); + gpio_reset_set(rcdev, 0); + + if (drvdata->post_delay_ms < 0) + return 0; + + msleep(drvdata->post_delay_ms); + return 0; +} + +static int gpio_reset_assert(struct reset_controller_dev *rcdev, + unsigned long id) +{ + gpio_reset_set(rcdev, 1); + + return 0; +} + +static int gpio_reset_deassert(struct reset_controller_dev *rcdev, + unsigned long id) +{ + gpio_reset_set(rcdev, 0); + + return 0; +} + +static struct reset_control_ops gpio_reset_ops = { + .reset = gpio_reset, + .assert = gpio_reset_assert, + .deassert = gpio_reset_deassert, +}; + +static int of_gpio_reset_xlate(struct reset_controller_dev *rcdev, + const struct of_phandle_args *reset_spec) +{ + if (WARN_ON(reset_spec->args_count != 0)) + return -EINVAL; + + return 0; +} + +static int gpio_reset_probe(struct platform_device *pdev) +{ + struct device_node *np = pdev->dev.of_node; + struct gpio_reset_data *drvdata; + enum of_gpio_flags flags; + unsigned long gpio_flags; + bool initially_in_reset; + int ret; + + drvdata = devm_kzalloc(&pdev->dev, sizeof(*drvdata), GFP_KERNEL); + if (drvdata == NULL) + return -ENOMEM; + + if (of_gpio_named_count(np, "reset-gpios") != 1) { + dev_err(&pdev->dev, + "reset-gpios property missing, or not a single gpio\n"); + return -EINVAL; + } + + drvdata->gpio = of_get_named_gpio_flags(np, "reset-gpios", 0, &flags); + if (drvdata->gpio == -EPROBE_DEFER) { + return drvdata->gpio; + } else if (!gpio_is_valid(drvdata->gpio)) { + dev_err(&pdev->dev, "invalid reset gpio: %d\n", drvdata->gpio); + return drvdata->gpio; + } + + drvdata->active_low = flags & OF_GPIO_ACTIVE_LOW; + + ret = of_property_read_u32(np, "reset-delay-us", &drvdata->delay_us); + if (ret < 0) + drvdata->delay_us = -1; + else if (drvdata->delay_us < 0) + dev_warn(&pdev->dev, "reset delay too high\n"); + + /* It is optional. + * Some devices need some milliseconds to wait after reset. + */ + ret = of_property_read_u32(np, "reset-post-delay-ms", &drvdata->post_delay_ms); + if (ret < 0) + drvdata->post_delay_ms = -1; + + initially_in_reset = of_property_read_bool(np, "initially-in-reset"); + if (drvdata->active_low ^ initially_in_reset) + gpio_flags = GPIOF_OUT_INIT_HIGH; + else + gpio_flags = GPIOF_OUT_INIT_LOW; + + ret = devm_gpio_request_one(&pdev->dev, drvdata->gpio, gpio_flags, NULL); + if (ret < 0) { + dev_err(&pdev->dev, "failed to request gpio %d: %d\n", + drvdata->gpio, ret); + return ret; + } + + platform_set_drvdata(pdev, drvdata); + + drvdata->rcdev.of_node = np; + drvdata->rcdev.owner = THIS_MODULE; + drvdata->rcdev.nr_resets = 1; + drvdata->rcdev.ops = &gpio_reset_ops; + drvdata->rcdev.of_xlate = of_gpio_reset_xlate; + reset_controller_register(&drvdata->rcdev); + + return 0; +} + +static int gpio_reset_remove(struct platform_device *pdev) +{ + struct gpio_reset_data *drvdata = platform_get_drvdata(pdev); + + reset_controller_unregister(&drvdata->rcdev); + + return 0; +} + +static struct of_device_id gpio_reset_dt_ids[] = { + { .compatible = "gpio-reset" }, + { } +}; + +#ifdef CONFIG_PM_SLEEP +static int gpio_reset_suspend(struct device *dev) +{ + pinctrl_pm_select_sleep_state(dev); + + return 0; +} +static int gpio_reset_resume(struct device *dev) +{ + pinctrl_pm_select_default_state(dev); + + return 0; +} +#endif + +static const struct dev_pm_ops gpio_reset_pm_ops = { + SET_LATE_SYSTEM_SLEEP_PM_OPS(gpio_reset_suspend, gpio_reset_resume) +}; + +static struct platform_driver gpio_reset_driver = { + .probe = gpio_reset_probe, + .remove = gpio_reset_remove, + .driver = { + .name = "gpio-reset", + .owner = THIS_MODULE, + .of_match_table = of_match_ptr(gpio_reset_dt_ids), + .pm = &gpio_reset_pm_ops, + }, +}; + +static int __init gpio_reset_init(void) +{ + return platform_driver_register(&gpio_reset_driver); +} +arch_initcall(gpio_reset_init); + +static void __exit gpio_reset_exit(void) +{ + platform_driver_unregister(&gpio_reset_driver); +} +module_exit(gpio_reset_exit); + +MODULE_AUTHOR("Philipp Zabel <p.zabel@pengutronix.de>"); +MODULE_DESCRIPTION("gpio reset controller"); +MODULE_LICENSE("GPL"); +MODULE_ALIAS("platform:gpio-reset"); +MODULE_DEVICE_TABLE(of, gpio_reset_dt_ids); |