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 <p.za...@pengutronix.de> --- Changes since v2: - Fill reset_controller_dev.owner field. - Renamed "gpios" device tree property to "reset-gpios". - Added device tree binding documentation. --- .../devicetree/bindings/reset/gpio-reset.txt | 32 ++++ drivers/reset/Kconfig | 13 ++ drivers/reset/Makefile | 1 + drivers/reset/gpio-reset.c | 189 ++++++++++++++++++++ 4 files changed, 235 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 0000000..9dd8781 --- /dev/null +++ b/Documentation/devicetree/bindings/reset/gpio-reset.txt @@ -0,0 +1,31 @@ +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-delays: List of delays in ms. The corresponding gpio reset line is + asserted for this duration to reset. +- #reset-cells: 1, see below + +example: + +gpio_reset: gpio-reset { + compatible = "gpio-reset"; + reset-gpios = <&gpio5 0 1>; /* active-low */ + reset-delays = <10>; /* 10 ms */ + #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 c9d04f7..e728d36 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 1e2d83f..b854f20 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 0000000..80a1807 --- /dev/null +++ b/drivers/reset/gpio-reset.c @@ -0,0 +1,189 @@ +/* + * Copyright 2013 Philipp Zabel, Pengutronix + */ +#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/reset-controller.h> + +struct gpio_reset { + unsigned int gpio; + unsigned long flags; + unsigned int delay_ms; +}; + +struct gpio_reset_data { + struct reset_controller_dev rcdev; + struct gpio_reset *gpios; + int nr_gpios; +}; + +static void __gpio_reset_set(struct gpio_reset_data *drvdata, + unsigned long gpio_idx, int asserted) +{ + int value = asserted; + + if (drvdata->gpios[gpio_idx].flags == GPIOF_OUT_INIT_HIGH) + 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 >= drvdata->nr_gpios) + return -EINVAL; + + if (drvdata->gpios[gpio_idx].delay_ms < 0) + return -ENOSYS; + + __gpio_reset_set(drvdata, gpio_idx, 1); + mdelay(drvdata->gpios[gpio_idx].delay_ms); + __gpio_reset_set(drvdata, gpio_idx, 0); + + return 0; +} + +static int gpio_reset_assert(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 >= drvdata->nr_gpios) + return -EINVAL; + + __gpio_reset_set(drvdata, gpio_idx, 1); + + return 0; +} + +static int gpio_reset_deassert(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 >= drvdata->nr_gpios) + return -EINVAL; + + __gpio_reset_set(drvdata, 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 *delays = NULL; + int ret; + int i; + + drvdata = devm_kzalloc(&pdev->dev, sizeof(*drvdata), GFP_KERNEL); + if (drvdata == NULL) + return -ENOMEM; + + drvdata->nr_gpios = of_gpio_named_count(np, "reset-gpios"); + if (drvdata->nr_gpios < 1) + return -EINVAL; + + drvdata->gpios = devm_kzalloc(&pdev->dev, sizeof(struct gpio_reset) * + drvdata->nr_gpios, GFP_KERNEL); + if (drvdata->gpios == NULL) + return -ENOMEM; + + if (of_find_property(np, "reset-delays", NULL)) { + delays = devm_kzalloc(&pdev->dev, sizeof(u32) * + drvdata->nr_gpios, GFP_KERNEL); + if (delays == NULL) + return -ENOMEM; + + ret = of_property_read_u32_array(np, "reset-delays", delays, + drvdata->nr_gpios); + if (ret < 0) + return ret; + } + + for (i = 0; i < drvdata->nr_gpios; i++) { + drvdata->gpios[i].gpio = of_get_named_gpio_flags(np, + "reset-gpios", i, &flags); + if (drvdata->gpios[i].gpio < 0) { + dev_err(&pdev->dev, "invalid gpio for reset %d\n", i); + return drvdata->gpios[i].gpio; + } + + /* + * The flags are also used to remember whether a given GPIO + * reset is active-low. + */ + if (flags & OF_GPIO_ACTIVE_LOW) + drvdata->gpios[i].flags = GPIOF_OUT_INIT_HIGH; + else + drvdata->gpios[i].flags = GPIOF_OUT_INIT_LOW; + + ret = devm_gpio_request_one(&pdev->dev, drvdata->gpios[i].gpio, + drvdata->gpios[i].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; + } + + if (delays != NULL) + drvdata->gpios[i].delay_ms = delays[i]; + else + drvdata->gpios[i].delay_ms = -1; /* .reset returns -ENOSYS */ + } + + devm_kfree(&pdev->dev, delays); + + drvdata->rcdev.of_node = np; + drvdata->rcdev.owner = THIS_MODULE; + 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); -- 1.7.10.4 _______________________________________________ devicetree-discuss mailing list devicetree-discuss@lists.ozlabs.org https://lists.ozlabs.org/listinfo/devicetree-discuss