From 3e6e69e1e3027427530cabfe9b93358eb477e877 Mon Sep 17 00:00:00 2001 From: Philipp Zabel Date: Mon, 19 Nov 2012 17:24:09 +0100 Subject: [PATCH] reset: Add driver for gpio-controlled reset pins This driver implements a reset controller device that toggles gpios connected to reset pins of peripheral ICs. The delay between assertion and de-assertion of the reset signal can be configured. Signed-off-by: Philipp Zabel Reviewed-by: Stephen Warren Reviewed-by: Marek Vasut Reviewed-by: Shawn Guo Reviewed-by: Pavel Machek --- .../devicetree/bindings/reset/gpio-reset.txt | 37 ++++ drivers/reset/Kconfig | 13 ++ drivers/reset/Makefile | 1 + drivers/reset/gpio-reset.c | 208 ++++++++++++++++++ 4 files changed, 259 insertions(+) create mode 100644 Documentation/devicetree/bindings/reset/gpio-reset.txt create mode 100644 drivers/reset/gpio-reset.c diff --git a/Documentation/devicetree/bindings/reset/gpio-reset.txt b/Documentation/devicetree/bindings/reset/gpio-reset.txt new file mode 100644 index 000000000000..1f203ebe34b0 --- /dev/null +++ b/Documentation/devicetree/bindings/reset/gpio-reset.txt @@ -0,0 +1,37 @@ +GPIO reset controller +===================== + +A GPIO reset controller controls a number of GPIOs that are connected +to reset pins of peripheral ICs. + +Please also refer to reset.txt in this directory for common reset +controller binding usage. + +Required properties: +- compatible: Should be "gpio-reset" +- reset-gpios: List of gpios used as reset lines. The gpio specifier for this + property depends on the gpio controller that provides the gpio. +- #reset-cells: 1, see below + +Optional properties: +- reset-delays: List of delays in microseconds. The corresponding gpio reset + line should be asserted for this duration to reset. +- initially-in-reset: List of integers. Zero if the initial state should be + a deasserted reset line, nonzero if the line should be + kept in reset. + +example: + +gpio_reset: gpio-reset { + compatible = "gpio-reset"; + reset-gpios = <&gpio5 0 1>; /* active-low */ + reset-delays = <10000>; /* 10 ms */ + initially-in-reset: <1>; + #reset-cells = <1>; +}; + +/* Device with nRESET pin connected to GPIO5_0 */ +sii902x@39 { + /* ... */ + resets = <&gpio_reset 0>; /* active-low GPIO5_0, 10 ms reset delay */ +}; diff --git a/drivers/reset/Kconfig b/drivers/reset/Kconfig index c9d04f797862..e728d362018f 100644 --- a/drivers/reset/Kconfig +++ b/drivers/reset/Kconfig @@ -11,3 +11,16 @@ menuconfig RESET_CONTROLLER via GPIOs or SoC-internal reset controller modules. If unsure, say no. + +if RESET_CONTROLLER + +config RESET_GPIO + tristate "GPIO reset controller support" + depends on GENERIC_GPIO + help + This driver provides support for reset lines that are controlled + directly by GPIOs. + The delay between assertion and de-assertion of the reset signal + can be configured. + +endif diff --git a/drivers/reset/Makefile b/drivers/reset/Makefile index 1e2d83f2b995..b854f208dfa1 100644 --- a/drivers/reset/Makefile +++ b/drivers/reset/Makefile @@ -1 +1,2 @@ obj-$(CONFIG_RESET_CONTROLLER) += core.o +obj-$(CONFIG_RESET_GPIO) += gpio-reset.o diff --git a/drivers/reset/gpio-reset.c b/drivers/reset/gpio-reset.c new file mode 100644 index 000000000000..3e3c36325942 --- /dev/null +++ b/drivers/reset/gpio-reset.c @@ -0,0 +1,208 @@ +/* + * 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 +#include +#include +#include +#include +#include +#include + +struct gpio_reset { + unsigned int gpio; + bool active_low; +}; + +struct gpio_reset_data { + struct reset_controller_dev rcdev; + /* these arrays contain a number of elements equal to rcdev.nr_resets */ + struct gpio_reset *gpios; + u32 *delays_us; +}; + +static void __gpio_reset_set(struct reset_controller_dev *rcdev, + unsigned long gpio_idx, int asserted) +{ + struct gpio_reset_data *drvdata = container_of(rcdev, + struct gpio_reset_data, rcdev); + int value = asserted; + + if (drvdata->gpios[gpio_idx].active_low) + value = !value; + + gpio_set_value(drvdata->gpios[gpio_idx].gpio, value); +} + +static int gpio_reset(struct reset_controller_dev *rcdev, + unsigned long gpio_idx) +{ + struct gpio_reset_data *drvdata = container_of(rcdev, + struct gpio_reset_data, rcdev); + + if (gpio_idx >= rcdev->nr_resets) + return -EINVAL; + + if (drvdata->delays_us == NULL) + return -ENOSYS; + + __gpio_reset_set(rcdev, gpio_idx, 1); + udelay(drvdata->delays_us[gpio_idx]); + __gpio_reset_set(rcdev, gpio_idx, 0); + + return 0; +} + +static int gpio_reset_assert(struct reset_controller_dev *rcdev, + unsigned long gpio_idx) +{ + if (gpio_idx >= rcdev->nr_resets) + return -EINVAL; + + __gpio_reset_set(rcdev, gpio_idx, 1); + + return 0; +} + +static int gpio_reset_deassert(struct reset_controller_dev *rcdev, + unsigned long gpio_idx) +{ + if (gpio_idx >= rcdev->nr_resets) + return -EINVAL; + + __gpio_reset_set(rcdev, gpio_idx, 0); + + return 0; +} + +static struct reset_control_ops gpio_reset_ops = { + .reset = gpio_reset, + .assert = gpio_reset_assert, + .deassert = gpio_reset_deassert, +}; + +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; + u32 *initially_in_reset; + int nr_gpios; + int ret; + int i; + + drvdata = devm_kzalloc(&pdev->dev, sizeof(*drvdata), GFP_KERNEL); + if (drvdata == NULL) + return -ENOMEM; + + nr_gpios = of_gpio_named_count(np, "reset-gpios"); + if (nr_gpios < 1) + return -EINVAL; + + drvdata->gpios = devm_kzalloc(&pdev->dev, sizeof(struct gpio_reset) * + nr_gpios, GFP_KERNEL); + if (drvdata->gpios == NULL) + return -ENOMEM; + + for (i = 0; i < nr_gpios; i++) { + drvdata->gpios[i].gpio = of_get_named_gpio_flags(np, + "reset-gpios", i, &flags); + if (drvdata->gpios[i].gpio == -EPROBE_DEFER) + return drvdata->gpios[i].gpio; + else if (drvdata->gpios[i].gpio < 0) { + dev_err(&pdev->dev, "invalid gpio for reset %d\n", i); + return drvdata->gpios[i].gpio; + } + + drvdata->gpios[i].active_low = flags & OF_GPIO_ACTIVE_LOW; + } + + if (of_find_property(np, "reset-delays", NULL)) { + drvdata->delays_us = devm_kzalloc(&pdev->dev, sizeof(u32) * + nr_gpios, GFP_KERNEL); + if (drvdata->delays_us == NULL) + return -ENOMEM; + + ret = of_property_read_u32_array(np, "reset-delays", + drvdata->delays_us, nr_gpios); + if (ret < 0) + return ret; + } + + initially_in_reset = devm_kzalloc(&pdev->dev, sizeof(u32) * + nr_gpios, GFP_KERNEL); + if (initially_in_reset == NULL) + return -ENOMEM; + if (of_find_property(np, "initially-in-reset", NULL)) { + ret = of_property_read_u32_array(np, "initially-in-reset", + initially_in_reset, nr_gpios); + if (ret < 0) + return ret; + } + + for (i = 0; i < nr_gpios; i++) { + unsigned long gpio_flags = GPIOF_OUT_INIT_LOW; + + if (drvdata->gpios[i].active_low ^ (!!initially_in_reset[i])) + gpio_flags = GPIOF_OUT_INIT_HIGH; + + ret = devm_gpio_request_one(&pdev->dev, drvdata->gpios[i].gpio, + gpio_flags, NULL); + if (ret < 0) { + dev_err(&pdev->dev, "failed to request gpio %d for reset %d\n", + drvdata->gpios[i].gpio, i); + return ret; + } + } + + devm_kfree(&pdev->dev, initially_in_reset); + + drvdata->rcdev.of_node = np; + drvdata->rcdev.owner = THIS_MODULE; + drvdata->rcdev.nr_resets = nr_gpios; + drvdata->rcdev.ops = &gpio_reset_ops; + reset_controller_register(&drvdata->rcdev); + + platform_set_drvdata(pdev, drvdata); + + 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" }, + { } +}; + +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), + }, +}; + +module_platform_driver(gpio_reset_driver); + +MODULE_AUTHOR("Philipp Zabel "); +MODULE_DESCRIPTION("gpio reset controller"); +MODULE_LICENSE("GPL"); +MODULE_ALIAS("platform:gpio-reset"); +MODULE_DEVICE_TABLE(of, gpio_reset_dt_ids); -- 2.39.5