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linux-next/drivers/gpio/gpiolib.h
Linus Walleij ff2b135922 gpio: make the gpiochip a real device 
GPIO chips have been around for years, but were never real devices,
instead they were piggy-backing on a parent device (such as a
platform_device or amba_device) but this was always optional.
GPIO chips could also exist without any device at all, with its
struct device *parent (ex *dev) pointer being set to null.

When sysfs was in use, a mock device would be created, with the
optional parent assigned, or just floating orphaned with NULL
as parent.

If sysfs is active, it will use this device as parent.

We now create a gpio_device struct containing a real
struct device and move the subsystem over to using that. The
list of struct gpio_chip:s is augmented to hold struct
gpio_device:s and we find gpio_chips:s by first looking up
the struct gpio_device.

The struct gpio_device is designed to stay around even if the
gpio_chip is removed, so as to satisfy users in userspace
that need a backing data structure to hold the state of the
session initiated with e.g. a character device even if there is
no physical chip anymore.

From this point on, gpiochips are devices.

Cc: Johan Hovold <johan@kernel.org>
Cc: Michael Welling <mwelling@ieee.org>
Cc: Markus Pargmann <mpa@pengutronix.de>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2016-02-09 11:03:53 +01:00

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/*
* Internal GPIO functions.
*
* Copyright (C) 2013, Intel Corporation
* Author: Mika Westerberg <mika.westerberg@linux.intel.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#ifndef GPIOLIB_H
#define GPIOLIB_H
#include <linux/gpio/driver.h>
#include <linux/err.h>
#include <linux/device.h>
#include <linux/module.h>
#include <linux/cdev.h>
enum of_gpio_flags;
enum gpiod_flags;
struct acpi_device;
/**
* struct gpio_device - internal state container for GPIO devices
* @id: numerical ID number for the GPIO chip
* @dev: the GPIO device struct
* @owner: helps prevent removal of modules exporting active GPIOs
* @chip: pointer to the corresponding gpiochip, holding static
* data for this device
* @list: links gpio_device:s together for traversal
*
* This state container holds most of the runtime variable data
* for a GPIO device and can hold references and live on after the
* GPIO chip has been removed, if it is still being used from
* userspace.
*/
struct gpio_device {
int id;
struct device dev;
struct module *owner;
struct gpio_chip *chip;
struct list_head list;
};
/**
* struct acpi_gpio_info - ACPI GPIO specific information
* @gpioint: if %true this GPIO is of type GpioInt otherwise type is GpioIo
* @active_low: in case of @gpioint, the pin is active low
*/
struct acpi_gpio_info {
bool gpioint;
int polarity;
int triggering;
};
/* gpio suffixes used for ACPI and device tree lookup */
static const char * const gpio_suffixes[] = { "gpios", "gpio" };
#ifdef CONFIG_ACPI
void acpi_gpiochip_add(struct gpio_chip *chip);
void acpi_gpiochip_remove(struct gpio_chip *chip);
void acpi_gpiochip_request_interrupts(struct gpio_chip *chip);
void acpi_gpiochip_free_interrupts(struct gpio_chip *chip);
struct gpio_desc *acpi_get_gpiod_by_index(struct acpi_device *adev,
const char *propname, int index,
struct acpi_gpio_info *info);
struct gpio_desc *acpi_node_get_gpiod(struct fwnode_handle *fwnode,
const char *propname, int index,
struct acpi_gpio_info *info);
int acpi_gpio_count(struct device *dev, const char *con_id);
bool acpi_can_fallback_to_crs(struct acpi_device *adev, const char *con_id);
#else
static inline void acpi_gpiochip_add(struct gpio_chip *chip) { }
static inline void acpi_gpiochip_remove(struct gpio_chip *chip) { }
static inline void
acpi_gpiochip_request_interrupts(struct gpio_chip *chip) { }
static inline void
acpi_gpiochip_free_interrupts(struct gpio_chip *chip) { }
static inline struct gpio_desc *
acpi_get_gpiod_by_index(struct acpi_device *adev, const char *propname,
int index, struct acpi_gpio_info *info)
{
return ERR_PTR(-ENOSYS);
}
static inline struct gpio_desc *
acpi_node_get_gpiod(struct fwnode_handle *fwnode, const char *propname,
int index, struct acpi_gpio_info *info)
{
return ERR_PTR(-ENXIO);
}
static inline int acpi_gpio_count(struct device *dev, const char *con_id)
{
return -ENODEV;
}
static inline bool acpi_can_fallback_to_crs(struct acpi_device *adev,
const char *con_id)
{
return false;
}
#endif
struct gpio_desc *of_get_named_gpiod_flags(struct device_node *np,
const char *list_name, int index, enum of_gpio_flags *flags);
struct gpio_desc *gpiochip_get_desc(struct gpio_chip *chip, u16 hwnum);
extern struct spinlock gpio_lock;
extern struct list_head gpio_devices;
struct gpio_desc {
struct gpio_chip *chip;
unsigned long flags;
/* flag symbols are bit numbers */
#define FLAG_REQUESTED 0
#define FLAG_IS_OUT 1
#define FLAG_EXPORT 2 /* protected by sysfs_lock */
#define FLAG_SYSFS 3 /* exported via /sys/class/gpio/control */
#define FLAG_ACTIVE_LOW 6 /* value has active low */
#define FLAG_OPEN_DRAIN 7 /* Gpio is open drain type */
#define FLAG_OPEN_SOURCE 8 /* Gpio is open source type */
#define FLAG_USED_AS_IRQ 9 /* GPIO is connected to an IRQ */
#define FLAG_IS_HOGGED 11 /* GPIO is hogged */
/* Connection label */
const char *label;
/* Name of the GPIO */
const char *name;
};
int gpiod_request(struct gpio_desc *desc, const char *label);
void gpiod_free(struct gpio_desc *desc);
int gpiod_hog(struct gpio_desc *desc, const char *name,
unsigned long lflags, enum gpiod_flags dflags);
/*
* Return the GPIO number of the passed descriptor relative to its chip
*/
static int __maybe_unused gpio_chip_hwgpio(const struct gpio_desc *desc)
{
return desc - &desc->chip->desc[0];
}
/* With descriptor prefix */
#define gpiod_emerg(desc, fmt, ...) \
pr_emerg("gpio-%d (%s): " fmt, desc_to_gpio(desc), desc->label ? : "?",\
##__VA_ARGS__)
#define gpiod_crit(desc, fmt, ...) \
pr_crit("gpio-%d (%s): " fmt, desc_to_gpio(desc), desc->label ? : "?", \
##__VA_ARGS__)
#define gpiod_err(desc, fmt, ...) \
pr_err("gpio-%d (%s): " fmt, desc_to_gpio(desc), desc->label ? : "?", \
##__VA_ARGS__)
#define gpiod_warn(desc, fmt, ...) \
pr_warn("gpio-%d (%s): " fmt, desc_to_gpio(desc), desc->label ? : "?", \
##__VA_ARGS__)
#define gpiod_info(desc, fmt, ...) \
pr_info("gpio-%d (%s): " fmt, desc_to_gpio(desc), desc->label ? : "?", \
##__VA_ARGS__)
#define gpiod_dbg(desc, fmt, ...) \
pr_debug("gpio-%d (%s): " fmt, desc_to_gpio(desc), desc->label ? : "?",\
##__VA_ARGS__)
/* With chip prefix */
#define chip_emerg(chip, fmt, ...) \
pr_emerg("GPIO chip %s: " fmt, chip->label, ##__VA_ARGS__)
#define chip_crit(chip, fmt, ...) \
pr_crit("GPIO chip %s: " fmt, chip->label, ##__VA_ARGS__)
#define chip_err(chip, fmt, ...) \
pr_err("GPIO chip %s: " fmt, chip->label, ##__VA_ARGS__)
#define chip_warn(chip, fmt, ...) \
pr_warn("GPIO chip %s: " fmt, chip->label, ##__VA_ARGS__)
#define chip_info(chip, fmt, ...) \
pr_info("GPIO chip %s: " fmt, chip->label, ##__VA_ARGS__)
#define chip_dbg(chip, fmt, ...) \
pr_debug("GPIO chip %s: " fmt, chip->label, ##__VA_ARGS__)
#ifdef CONFIG_GPIO_SYSFS
int gpiochip_sysfs_register(struct gpio_chip *chip);
void gpiochip_sysfs_unregister(struct gpio_chip *chip);
#else
static inline int gpiochip_sysfs_register(struct gpio_chip *chip)
{
return 0;
}
static inline void gpiochip_sysfs_unregister(struct gpio_chip *chip)
{
}
#endif /* CONFIG_GPIO_SYSFS */
#endif /* GPIOLIB_H */
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