From patchwork Tue May 28 15:06:15 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Philipp Zabel X-Patchwork-Id: 2625491 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-process-083081@patchwork1.kernel.org Received: from casper.infradead.org (casper.infradead.org [85.118.1.10]) by patchwork1.kernel.org (Postfix) with ESMTP id 1ABD93FDBC for ; Tue, 28 May 2013 15:08:26 +0000 (UTC) Received: from merlin.infradead.org ([2001:4978:20e::2]) by casper.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1UhLVC-0002MM-K3; Tue, 28 May 2013 15:07:55 +0000 Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1UhLUw-0008Mz-8L; Tue, 28 May 2013 15:07:38 +0000 Received: from metis.ext.pengutronix.de ([2001:6f8:1178:4:290:27ff:fe1d:cc33]) by merlin.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1UhLUs-0008KB-Vd for linux-arm-kernel@lists.infradead.org; Tue, 28 May 2013 15:07:36 +0000 Received: from pizza.hi.pengutronix.de ([10.1.0.104] helo=pizza.pengutronix.de) by metis.ext.pengutronix.de with esmtp (Exim 4.72) (envelope-from ) id 1UhLUW-0002g1-C3; Tue, 28 May 2013 17:07:12 +0200 From: Philipp Zabel To: linux-arm-kernel@lists.infradead.org Subject: [PATCH v7] reset: Add driver for gpio-controlled reset pins Date: Tue, 28 May 2013 17:06:15 +0200 Message-Id: <1369753575-9818-1-git-send-email-p.zabel@pengutronix.de> X-Mailer: git-send-email 1.7.10.4 X-SA-Exim-Connect-IP: 10.1.0.104 X-SA-Exim-Mail-From: p.zabel@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-arm-kernel@lists.infradead.org X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20130528_110735_432558_52BF7E66 X-CRM114-Status: GOOD ( 27.60 ) X-Spam-Score: -3.0 (---) X-Spam-Report: SpamAssassin version 3.3.2 on merlin.infradead.org summary: Content analysis details: (-3.0 points) pts rule name description ---- ---------------------- -------------------------------------------------- -1.1 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: Marek Vasut , Fabio Estevam , Mike Turquette , Philipp Zabel , Arnd Bergmann , Stephen Warren , Sascha Hauer , "Rafael J. Wysocki" , Pavel Machek , Len Brown , Olof Johansson , Shawn Guo , devicetree-discuss@lists.ozlabs.org X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org This driver implements a reset controller device that toggle a gpio connected to a reset pin of a peripheral IC. The delay between assertion and de-assertion of the reset signal can be configured via device tree. Signed-off-by: Philipp Zabel Reviewed-by: Stephen Warren --- Changes since v6: - Switched to a single gpio per gpio-reset device, as Olof suggested. This should make the device tree binding more straightforward. - Changed reset delay property to reset-delay-us. --- .../devicetree/bindings/reset/gpio-reset.txt | 35 +++++ drivers/reset/Kconfig | 11 ++ drivers/reset/Makefile | 1 + drivers/reset/gpio-reset.c | 171 +++++++++++++++++++++ 4 files changed, 218 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..6f7476b --- /dev/null +++ b/Documentation/devicetree/bindings/reset/gpio-reset.txt @@ -0,0 +1,35 @@ +GPIO reset controller +===================== + +A GPIO reset controller controls a single GPIO that is connected to the reset +pin of a peripheral IC. Please also refer to reset.txt in this directory for +common reset controller binding usage. + +Required properties: +- compatible: Should be "gpio-reset" +- reset-gpios: A gpio used as reset line. The gpio specifier for this property + depends on the gpio controller that provides the gpio. +- #reset-cells: 0, see below + +Optional properties: +- reset-delay-us: delay in microseconds. The gpio reset line will be asserted for + this duration to reset. +- initially-in-reset: boolean. If not set, the initial state should be a + deasserted reset line. If this property exists, the + reset line should be kept in reset. + +example: + +sii902x_reset: gpio-reset { + compatible = "gpio-reset"; + reset-gpios = <&gpio5 0 GPIO_ACTIVE_LOW>; + reset-delay-us = <10000>; + initially-in-reset; + #reset-cells = <0>; +}; + +/* Device with nRESET pin connected to GPIO5_0 */ +sii902x@39 { + /* ... */ + resets = <&sii902x_reset>; /* active-low GPIO5_0, 10 ms delay */ +}; diff --git a/drivers/reset/Kconfig b/drivers/reset/Kconfig index c9d04f7..1a862df 100644 --- a/drivers/reset/Kconfig +++ b/drivers/reset/Kconfig @@ -11,3 +11,14 @@ 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 GPIOLIB && OF + help + This driver provides support for reset lines that are controlled + directly by GPIOs. + +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..7faea09 --- /dev/null +++ b/drivers/reset/gpio-reset.c @@ -0,0 +1,169 @@ +/* + * 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_data { + struct reset_controller_dev rcdev; + unsigned int gpio; + bool active_low; + u32 delay_us; +}; + +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(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); + + 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) + 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) + return ret; + + 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; + } + + 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); + + 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);