[RFC] GPIO lines [was: GPIO User I/O]

Message ID	070fa558-6e20-0fbf-d3e4-0a0eca4fe82c@enneenne.com
State	New
Headers	show Return-Path: <linux-gpio-owner@vger.kernel.org> Subject: [RFC] GPIO lines [was: GPIO User I/O] From: Rodolfo Giometti <giometti@enneenne.com> To: Geert Uytterhoeven <geert@linux-m68k.org>, Linus Walleij <linus.walleij@linaro.org> Cc: Geert Uytterhoeven <geert+renesas@glider.be>, "open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>, Bartosz Golaszewski <bgolaszewski@baylibre.com>, Rob Herring <robh+dt@kernel.org>, "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" <devicetree@vger.kernel.org> References: <01afcac0-bd34-3fd0-b991-a8b40d4b4561@enneenne.com> <CACRpkdbX9T9EuN-nxkMPC=sN74PEdoLuWurNLdGCzZJwwFrdpQ@mail.gmail.com> <1c4f1a83-835a-9317-3647-b55f6f39c0ba@enneenne.com> <CACRpkdZPjJSryJc+RtYjRN=X7xKMcao5pYek1fUM2+sE9xgdFQ@mail.gmail.com> <CAMuHMdUtguuu4FWU4nRS=pBUyEwKM1JZ8DYPdCQHXBYN0i_Frg@mail.gmail.com> <87efe96c-3679-14d5-4d79-569b6c047b00@enneenne.com> <CAMuHMdUght0hkJT1N8ub5xR5GB+U18MAhAg+zDmAAuxoRSRaYg@mail.gmail.com> <d30e64c9-ad7f-7cd5-51a4-3f37d6f1e3d8@enneenne.com> Message-ID: <070fa558-6e20-0fbf-d3e4-0a0eca4fe82c@enneenne.com> Date: Thu, 9 Jul 2020 16:11:20 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.8.0 MIME-Version: 1.0 In-Reply-To: <d30e64c9-ad7f-7cd5-51a4-3f37d6f1e3d8@enneenne.com> Content-Type: multipart/mixed; boundary="------------349B4E7446A5F5834C3D4114" Content-Language: en-US Sender: linux-gpio-owner@vger.kernel.org Precedence: bulk
Series	[RFC] GPIO lines [was: GPIO User I/O] \| expand [RFC] GPIO lines [was: GPIO User I/O]

diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig index 4f52c3a8ec99..f117b0b9d33e 100644 --- a/drivers/gpio/Kconfig +++ b/drivers/gpio/Kconfig @@ -73,6 +73,16 @@ config GPIO_SYSFS Kernel drivers may also request that a particular GPIO be exported to userspace; this can be useful when debugging. +config GPIO_LINE + bool "/sys/class/line/... (GPIO lines interface)" + depends on SYSFS + help + Say Y here to add a sysfs interface to manage system's GPIO lines. + + Instead of the GPIO_SYSFS support, by using this support, you'll be + able to use GPIOs from userspace as stated in the device-tree + for well defined pourposes and by using proper names. + config GPIO_GENERIC depends on HAS_IOMEM # Only for IOMEM drivers tristate diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile index c256aff66a65..033a6b836dec 100644 --- a/drivers/gpio/Makefile +++ b/drivers/gpio/Makefile @@ -9,6 +9,7 @@ obj-$(CONFIG_GPIOLIB) += gpiolib-legacy.o obj-$(CONFIG_GPIOLIB) += gpiolib-devprop.o obj-$(CONFIG_OF_GPIO) += gpiolib-of.o obj-$(CONFIG_GPIO_SYSFS) += gpiolib-sysfs.o +obj-$(CONFIG_GPIO_LINE) += gpiolib-line.o obj-$(CONFIG_GPIO_ACPI) += gpiolib-acpi.o # Device drivers. Generally keep list sorted alphabetically diff --git a/drivers/gpio/gpiolib-line.c b/drivers/gpio/gpiolib-line.c new file mode 100644 index 000000000000..8abd08c1a5e3 --- /dev/null +++ b/drivers/gpio/gpiolib-line.c @@ -0,0 +1,256 @@ +/* + * GPIOlib - userspace I/O line interface + * + * + * Copyright (C) 2020 Rodolfo Giometti <giometti@enneenne.com> + * + * 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. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. + */ + +#include <linux/kernel.h> +#include <linux/init.h> +#include <linux/device.h> +#include <linux/idr.h> +#include <linux/kdev_t.h> +#include <linux/mutex.h> +#include <linux/platform_device.h> +#include <linux/property.h> +#include <linux/gpio.h> +#include <linux/gpio/consumer.h> + +#define GPIO_LINE_MAX_SOURCES 128 /* should be enough... */ + +/* + * Local variables + */ + +static dev_t gpio_line_devt; +static struct class *gpio_line_class; + +static DEFINE_MUTEX(gpio_line_idr_lock); +static DEFINE_IDR(gpio_line_idr); + +struct gpio_line_device { + struct gpio_desc *gpiod; + const char *name; + unsigned int id; + struct device *dev; +}; + +/* + * sysfs methods + */ + +static ssize_t state_store(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t count) +{ + struct gpio_line_device *gpio_line = dev_get_drvdata(dev); + int status, ret; + + ret = sscanf(buf, "%d", &status); + if (ret != 1 && status != 0 && status != 1) + return -EINVAL; + + gpiod_set_value_cansleep(gpio_line->gpiod, status); + + return count; +} + +static ssize_t state_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct gpio_line_device *gpio_line = dev_get_drvdata(dev); + int status = gpiod_get_value_cansleep(gpio_line->gpiod); + + return sprintf(buf, "%d\n", status); +} +static DEVICE_ATTR_RW(state); + +/* + * Class attributes + */ + +static struct attribute *gpio_line_attrs[] = { + &dev_attr_state.attr, + NULL, +}; + +static const struct attribute_group gpio_line_group = { + .attrs = gpio_line_attrs, +}; + +static const struct attribute_group *gpio_line_groups[] = { + &gpio_line_group, + NULL, +}; + +/* + * Driver stuff + */ + +static int gpio_line_create_entry(const char *name, + struct gpio_desc *gpiod, + struct device *parent) +{ + struct gpio_line_device *gpio_line; + dev_t devt; + int ret; + + /* First allocate a new gpio_line device */ + gpio_line = kmalloc(sizeof(struct gpio_line_device), GFP_KERNEL); + if (!gpio_line) + return -ENOMEM; + + mutex_lock(&gpio_line_idr_lock); + /* + * Get new ID for the new gpio_line source. After idr_alloc() calling + * the new source will be freely available into the kernel. + */ + ret = idr_alloc(&gpio_line_idr, gpio_line, 0, + GPIO_LINE_MAX_SOURCES, GFP_KERNEL); + if (ret < 0) { + if (ret == -ENOSPC) { + pr_err("%s: too many GPIO lines in the system\n", + name); + ret = -EBUSY; + } + goto error_device_create; + } + gpio_line->id = ret; + mutex_unlock(&gpio_line_idr_lock); + + /* Create the device and init the device's data */ + devt = MKDEV(MAJOR(gpio_line_devt), gpio_line->id); + gpio_line->dev = device_create(gpio_line_class, parent, devt, gpio_line, + "%s", name); + if (IS_ERR(gpio_line->dev)) { + dev_err(gpio_line->dev, "unable to create device %s\n", name); + ret = PTR_ERR(gpio_line->dev); + goto error_idr_remove; + } + dev_set_drvdata(gpio_line->dev, gpio_line); + + /* Init the gpio_line data */ + gpio_line->gpiod = gpiod; + gpio_line->name = name; + + dev_info(gpio_line->dev, "added\n"); + + return 0; + +error_idr_remove: + mutex_lock(&gpio_line_idr_lock); + idr_remove(&gpio_line_idr, gpio_line->id); + +error_device_create: + mutex_unlock(&gpio_line_idr_lock); + kfree(gpio_line); + + return ret; +} + +static int gpio_line_gpio_probe(struct platform_device *pdev) +{ + struct device *dev = &pdev->dev; + struct fwnode_handle *child; + int ret; + + device_for_each_child_node(dev, child) { + struct device_node *np = to_of_node(child); + const char *label; + enum gpiod_flags flags = GPIOD_ASIS; + const char *mode = "as-is"; + struct gpio_desc *gpiod; + + ret = fwnode_property_read_string(child, "label", &label); + if (ret && IS_ENABLED(CONFIG_OF) && np) + label = np->name; + if (!label) { + dev_err(dev, + "label property not defined or invalid!\n"); + goto skip; + } + + ret = fwnode_property_read_string(child, "mode", &mode); + if ((ret == 0) && mode) { + if (strcmp("as-is", mode) == 0) + flags = GPIOD_ASIS; + else if (strcmp("input", mode) == 0) + flags = GPIOD_IN; + else if (strcmp("out-low", mode) == 0) + flags = GPIOD_OUT_LOW; + else if (strcmp("out-high", mode) == 0) + flags = GPIOD_OUT_HIGH; + else if (strcmp("out-low-open-drain", mode) == 0) + flags = GPIOD_OUT_LOW_OPEN_DRAIN; + else if (strcmp("out-high-open-drain", mode) == 0) + flags = GPIOD_OUT_HIGH_OPEN_DRAIN; + } + + gpiod = devm_fwnode_get_gpiod_from_child(dev, NULL, child, + flags, label); + if (IS_ERR(gpiod)) { + dev_err(dev, "gpios property not defined!\n"); + goto skip; + } + + ret = gpio_line_create_entry(label, gpiod, dev); + if (ret) + goto skip; + + /* Success, now go to the next child */ + continue; + +skip: /* Error, skip the child */ + fwnode_handle_put(child); + dev_err(dev, "failed to register GPIO lines interface\n"); + } + + return 0; +} + +static const struct of_device_id of_gpio_gpio_line_match[] = { + { .compatible = "gpio-line", }, + { /* sentinel */ } +}; + +static struct platform_driver gpio_line_gpio_driver = { + .driver = { + .name = "gpio-line", + .of_match_table = of_gpio_gpio_line_match, + }, +}; + +builtin_platform_driver_probe(gpio_line_gpio_driver, gpio_line_gpio_probe); + +/* + * Module stuff + */ + +static int __init gpiolib_line_init(void) +{ + /* Create the new class */ + gpio_line_class = class_create(THIS_MODULE, "line"); + if (!gpio_line_class) { + printk(KERN_ERR "gpio_line: failed to create class\n"); + return -ENOMEM; + } + gpio_line_class->dev_groups = gpio_line_groups; + + return 0; +} + +postcore_initcall(gpiolib_line_init);

[RFC] GPIO lines [was: GPIO User I/O]

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