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3c702e9987
A new chardev that is to be used for userspace GPIO access is added in this patch. It is intended to gradually replace the horribly broken sysfs ABI. Using a chardev has many upsides: - All operations are per-gpiochip, which is the actual device underlying the GPIOs, making us tie in to the kernel device model properly. - Hotpluggable GPIO controllers can come and go, as this kind of problem has been know to userspace for character devices since ages, and if a gpiochip handle is held in userspace we know we will break something, whereas the sysfs is stateless. - The one-value-per-file rule of sysfs is really hard to maintain when you want to twist more than one knob at a time, for example have in-kernel APIs to switch several GPIO lines at the same time, and this will be possible to do with a single ioctl() from userspace, saving a lot of context switching. We also need to add a new bus type for GPIO. This is necessary for example for userspace coldplug, where sysfs is traversed to find the boot-time device nodes and create the character devices in /dev. This new chardev ABI is *non* *optional* and can be counted on to be present in the future, emphasizing the preference of this ABI. The ABI only implements one single ioctl() to get the name and number of GPIO lines of a chip. Even this is debatable: see it as a minimal example for review. This ABI shall be ruthlessly reviewed and etched in stone. The old /sys/class/gpio is still optional to compile in, but will be deprecated. Unique device IDs are created using IDR, which is overkill and insanely scalable, but also well tested. Cc: Johan Hovold <johan@kernel.org> Cc: Michael Welling <mwelling@ieee.org> Cc: Markus Pargmann <mpa@pengutronix.de> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
209 lines
6.4 KiB
C
209 lines
6.4 KiB
C
/*
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* Internal GPIO functions.
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*
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* Copyright (C) 2013, Intel Corporation
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* Author: Mika Westerberg <mika.westerberg@linux.intel.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#ifndef GPIOLIB_H
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#define GPIOLIB_H
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#include <linux/gpio/driver.h>
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#include <linux/err.h>
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#include <linux/device.h>
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#include <linux/module.h>
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#include <linux/cdev.h>
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enum of_gpio_flags;
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enum gpiod_flags;
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struct acpi_device;
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/**
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* struct gpio_device - internal state container for GPIO devices
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* @id: numerical ID number for the GPIO chip
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* @dev: the GPIO device struct
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* @chrdev: character device for the GPIO device
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* @owner: helps prevent removal of modules exporting active GPIOs
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* @chip: pointer to the corresponding gpiochip, holding static
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* data for this device
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* @list: links gpio_device:s together for traversal
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*
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* This state container holds most of the runtime variable data
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* for a GPIO device and can hold references and live on after the
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* GPIO chip has been removed, if it is still being used from
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* userspace.
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*/
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struct gpio_device {
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int id;
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struct device dev;
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struct cdev chrdev;
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struct module *owner;
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struct gpio_chip *chip;
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struct list_head list;
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};
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/**
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* struct acpi_gpio_info - ACPI GPIO specific information
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* @gpioint: if %true this GPIO is of type GpioInt otherwise type is GpioIo
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* @active_low: in case of @gpioint, the pin is active low
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*/
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struct acpi_gpio_info {
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bool gpioint;
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int polarity;
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int triggering;
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};
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/* gpio suffixes used for ACPI and device tree lookup */
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static const char * const gpio_suffixes[] = { "gpios", "gpio" };
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#ifdef CONFIG_ACPI
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void acpi_gpiochip_add(struct gpio_chip *chip);
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void acpi_gpiochip_remove(struct gpio_chip *chip);
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void acpi_gpiochip_request_interrupts(struct gpio_chip *chip);
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void acpi_gpiochip_free_interrupts(struct gpio_chip *chip);
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struct gpio_desc *acpi_get_gpiod_by_index(struct acpi_device *adev,
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const char *propname, int index,
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struct acpi_gpio_info *info);
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struct gpio_desc *acpi_node_get_gpiod(struct fwnode_handle *fwnode,
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const char *propname, int index,
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struct acpi_gpio_info *info);
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int acpi_gpio_count(struct device *dev, const char *con_id);
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bool acpi_can_fallback_to_crs(struct acpi_device *adev, const char *con_id);
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#else
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static inline void acpi_gpiochip_add(struct gpio_chip *chip) { }
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static inline void acpi_gpiochip_remove(struct gpio_chip *chip) { }
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static inline void
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acpi_gpiochip_request_interrupts(struct gpio_chip *chip) { }
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static inline void
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acpi_gpiochip_free_interrupts(struct gpio_chip *chip) { }
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static inline struct gpio_desc *
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acpi_get_gpiod_by_index(struct acpi_device *adev, const char *propname,
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int index, struct acpi_gpio_info *info)
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{
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return ERR_PTR(-ENOSYS);
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}
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static inline struct gpio_desc *
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acpi_node_get_gpiod(struct fwnode_handle *fwnode, const char *propname,
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int index, struct acpi_gpio_info *info)
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{
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return ERR_PTR(-ENXIO);
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}
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static inline int acpi_gpio_count(struct device *dev, const char *con_id)
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{
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return -ENODEV;
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}
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static inline bool acpi_can_fallback_to_crs(struct acpi_device *adev,
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const char *con_id)
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{
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return false;
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}
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#endif
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struct gpio_desc *of_get_named_gpiod_flags(struct device_node *np,
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const char *list_name, int index, enum of_gpio_flags *flags);
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struct gpio_desc *gpiochip_get_desc(struct gpio_chip *chip, u16 hwnum);
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extern struct spinlock gpio_lock;
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extern struct list_head gpio_devices;
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struct gpio_desc {
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struct gpio_chip *chip;
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unsigned long flags;
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/* flag symbols are bit numbers */
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#define FLAG_REQUESTED 0
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#define FLAG_IS_OUT 1
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#define FLAG_EXPORT 2 /* protected by sysfs_lock */
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#define FLAG_SYSFS 3 /* exported via /sys/class/gpio/control */
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#define FLAG_ACTIVE_LOW 6 /* value has active low */
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#define FLAG_OPEN_DRAIN 7 /* Gpio is open drain type */
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#define FLAG_OPEN_SOURCE 8 /* Gpio is open source type */
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#define FLAG_USED_AS_IRQ 9 /* GPIO is connected to an IRQ */
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#define FLAG_IS_HOGGED 11 /* GPIO is hogged */
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/* Connection label */
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const char *label;
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/* Name of the GPIO */
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const char *name;
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};
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int gpiod_request(struct gpio_desc *desc, const char *label);
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void gpiod_free(struct gpio_desc *desc);
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int gpiod_hog(struct gpio_desc *desc, const char *name,
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unsigned long lflags, enum gpiod_flags dflags);
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/*
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* Return the GPIO number of the passed descriptor relative to its chip
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*/
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static int __maybe_unused gpio_chip_hwgpio(const struct gpio_desc *desc)
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{
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return desc - &desc->chip->desc[0];
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}
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/* With descriptor prefix */
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#define gpiod_emerg(desc, fmt, ...) \
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pr_emerg("gpio-%d (%s): " fmt, desc_to_gpio(desc), desc->label ? : "?",\
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##__VA_ARGS__)
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#define gpiod_crit(desc, fmt, ...) \
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pr_crit("gpio-%d (%s): " fmt, desc_to_gpio(desc), desc->label ? : "?", \
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##__VA_ARGS__)
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#define gpiod_err(desc, fmt, ...) \
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pr_err("gpio-%d (%s): " fmt, desc_to_gpio(desc), desc->label ? : "?", \
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##__VA_ARGS__)
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#define gpiod_warn(desc, fmt, ...) \
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pr_warn("gpio-%d (%s): " fmt, desc_to_gpio(desc), desc->label ? : "?", \
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##__VA_ARGS__)
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#define gpiod_info(desc, fmt, ...) \
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pr_info("gpio-%d (%s): " fmt, desc_to_gpio(desc), desc->label ? : "?", \
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##__VA_ARGS__)
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#define gpiod_dbg(desc, fmt, ...) \
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pr_debug("gpio-%d (%s): " fmt, desc_to_gpio(desc), desc->label ? : "?",\
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##__VA_ARGS__)
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/* With chip prefix */
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#define chip_emerg(chip, fmt, ...) \
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dev_emerg(&chip->gpiodev->dev, "(%s): " fmt, chip->label, ##__VA_ARGS__)
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#define chip_crit(chip, fmt, ...) \
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dev_crit(&chip->gpiodev->dev, "(%s): " fmt, chip->label, ##__VA_ARGS__)
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#define chip_err(chip, fmt, ...) \
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dev_err(&chip->gpiodev->dev, "(%s): " fmt, chip->label, ##__VA_ARGS__)
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#define chip_warn(chip, fmt, ...) \
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dev_warn(&chip->gpiodev->dev, "(%s): " fmt, chip->label, ##__VA_ARGS__)
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#define chip_info(chip, fmt, ...) \
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dev_info(&chip->gpiodev->dev, "(%s): " fmt, chip->label, ##__VA_ARGS__)
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#define chip_dbg(chip, fmt, ...) \
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dev_dbg(&chip->gpiodev->dev, "(%s): " fmt, chip->label, ##__VA_ARGS__)
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#ifdef CONFIG_GPIO_SYSFS
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int gpiochip_sysfs_register(struct gpio_chip *chip);
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void gpiochip_sysfs_unregister(struct gpio_chip *chip);
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#else
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static inline int gpiochip_sysfs_register(struct gpio_chip *chip)
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{
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return 0;
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}
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static inline void gpiochip_sysfs_unregister(struct gpio_chip *chip)
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{
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}
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#endif /* CONFIG_GPIO_SYSFS */
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#endif /* GPIOLIB_H */
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