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linux-stable/drivers/gpio/gpiolib.h
Bartosz Golaszewski efb8235bfd gpiolib: revert the attempt to protect the GPIO device list with an rwsem 
This reverts commits 1979a28075 ("gpiolib: replace the GPIO device
mutex with a read-write semaphore") and 65a828bab1 ("gpiolib: use
a mutex to protect the list of GPIO devices").

Unfortunately the legacy GPIO API that's still used in older code has to
translate numbers from the global GPIO numberspace to descriptors. This
results in a GPIO device lookup in every call to legacy functions. Some
of those functions - like gpio_set/get_value() - can be called from
atomic context so taking a sleeping lock that is an RW semaphore results
in an error.

We'll probably have to protect this list with SRCU.

Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/linux-wireless/f7b5ff1e-8f34-4d98-a7be-b826cb897dc8@moroto.mountain/
Fixes: 1979a28075 ("gpiolib: replace the GPIO device mutex with a read-write semaphore")
Fixes: 65a828bab1 ("gpiolib: use a mutex to protect the list of GPIO devices")
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2024-01-17 09:52:37 +01:00

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/* SPDX-License-Identifier: GPL-2.0 */
/*
* Internal GPIO functions.
*
* Copyright (C) 2013, Intel Corporation
* Author: Mika Westerberg <mika.westerberg@linux.intel.com>
*/
#ifndef GPIOLIB_H
#define GPIOLIB_H
#include <linux/cdev.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/gpio/consumer.h> /* for enum gpiod_flags */
#include <linux/gpio/driver.h>
#include <linux/module.h>
#include <linux/notifier.h>
#include <linux/rwsem.h>
#define GPIOCHIP_NAME "gpiochip"
/**
* struct gpio_device - internal state container for GPIO devices
* @dev: the GPIO device struct
* @chrdev: character device for the GPIO device
* @id: numerical ID number for the GPIO chip
* @mockdev: class device used by the deprecated sysfs interface (may be
* NULL)
* @owner: helps prevent removal of modules exporting active GPIOs
* @chip: pointer to the corresponding gpiochip, holding static
* data for this device
* @descs: array of ngpio descriptors.
* @ngpio: the number of GPIO lines on this GPIO device, equal to the size
* of the @descs array.
* @base: GPIO base in the DEPRECATED global Linux GPIO numberspace, assigned
* at device creation time.
* @label: a descriptive name for the GPIO device, such as the part number
* or name of the IP component in a System on Chip.
* @data: per-instance data assigned by the driver
* @list: links gpio_device:s together for traversal
* @line_state_notifier: used to notify subscribers about lines being
* requested, released or reconfigured
* @device_notifier: used to notify character device wait queues about the GPIO
* device being unregistered
* @sem: protects the structure from a NULL-pointer dereference of @chip by
* user-space operations when the device gets unregistered during
* a hot-unplug event
* @pin_ranges: range of pins served by the GPIO driver
*
* 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 {
struct device dev;
struct cdev chrdev;
int id;
struct device *mockdev;
struct module *owner;
struct gpio_chip *chip;
struct gpio_desc *descs;
int base;
u16 ngpio;
const char *label;
void *data;
struct list_head list;
struct blocking_notifier_head line_state_notifier;
struct blocking_notifier_head device_notifier;
struct rw_semaphore sem;
#ifdef CONFIG_PINCTRL
/*
* If CONFIG_PINCTRL is enabled, then gpio controllers can optionally
* describe the actual pin range which they serve in an SoC. This
* information would be used by pinctrl subsystem to configure
* corresponding pins for gpio usage.
*/
struct list_head pin_ranges;
#endif
};
static inline struct gpio_device *to_gpio_device(struct device *dev)
{
return container_of(dev, struct gpio_device, dev);
}
/* gpio suffixes used for ACPI and device tree lookup */
static __maybe_unused const char * const gpio_suffixes[] = { "gpios", "gpio" };
/**
* struct gpio_array - Opaque descriptor for a structure of GPIO array attributes
*
* @desc: Array of pointers to the GPIO descriptors
* @size: Number of elements in desc
* @chip: Parent GPIO chip
* @get_mask: Get mask used in fastpath
* @set_mask: Set mask used in fastpath
* @invert_mask: Invert mask used in fastpath
*
* This structure is attached to struct gpiod_descs obtained from
* gpiod_get_array() and can be passed back to get/set array functions in order
* to activate fast processing path if applicable.
*/
struct gpio_array {
struct gpio_desc **desc;
unsigned int size;
struct gpio_chip *chip;
unsigned long *get_mask;
unsigned long *set_mask;
unsigned long invert_mask[];
};
#define for_each_gpio_desc(gc, desc) \
for (unsigned int __i = 0; \
__i < gc->ngpio && (desc = gpiochip_get_desc(gc, __i)); \
__i++) \
#define for_each_gpio_desc_with_flag(gc, desc, flag) \
for_each_gpio_desc(gc, desc) \
if (!test_bit(flag, &desc->flags)) {} else
int gpiod_get_array_value_complex(bool raw, bool can_sleep,
unsigned int array_size,
struct gpio_desc **desc_array,
struct gpio_array *array_info,
unsigned long *value_bitmap);
int gpiod_set_array_value_complex(bool raw, bool can_sleep,
unsigned int array_size,
struct gpio_desc **desc_array,
struct gpio_array *array_info,
unsigned long *value_bitmap);
int gpiod_set_transitory(struct gpio_desc *desc, bool transitory);
extern spinlock_t gpio_lock;
extern struct list_head gpio_devices;
void gpiod_line_state_notify(struct gpio_desc *desc, unsigned long action);
/**
* struct gpio_desc - Opaque descriptor for a GPIO
*
* @gdev: Pointer to the parent GPIO device
* @flags: Binary descriptor flags
* @label: Name of the consumer
* @name: Line name
* @hog: Pointer to the device node that hogs this line (if any)
*
* These are obtained using gpiod_get() and are preferable to the old
* integer-based handles.
*
* Contrary to integers, a pointer to a &struct gpio_desc is guaranteed to be
* valid until the GPIO is released.
*/
struct gpio_desc {
struct gpio_device *gdev;
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_IRQ_IS_ENABLED 10 /* GPIO is connected to an enabled IRQ */
#define FLAG_IS_HOGGED 11 /* GPIO is hogged */
#define FLAG_TRANSITORY 12 /* GPIO may lose value in sleep or reset */
#define FLAG_PULL_UP 13 /* GPIO has pull up enabled */
#define FLAG_PULL_DOWN 14 /* GPIO has pull down enabled */
#define FLAG_BIAS_DISABLE 15 /* GPIO has pull disabled */
#define FLAG_EDGE_RISING 16 /* GPIO CDEV detects rising edge events */
#define FLAG_EDGE_FALLING 17 /* GPIO CDEV detects falling edge events */
#define FLAG_EVENT_CLOCK_REALTIME 18 /* GPIO CDEV reports REALTIME timestamps in events */
#define FLAG_EVENT_CLOCK_HTE 19 /* GPIO CDEV reports hardware timestamps in events */
/* Connection label */
const char *label;
/* Name of the GPIO */
const char *name;
#ifdef CONFIG_OF_DYNAMIC
struct device_node *hog;
#endif
};
#define gpiod_not_found(desc) (IS_ERR(desc) && PTR_ERR(desc) == -ENOENT)
int gpiod_request(struct gpio_desc *desc, const char *label);
void gpiod_free(struct gpio_desc *desc);
static inline int gpiod_request_user(struct gpio_desc *desc, const char *label)
{
int ret;
ret = gpiod_request(desc, label);
if (ret == -EPROBE_DEFER)
ret = -ENODEV;
return ret;
}
int gpiod_configure_flags(struct gpio_desc *desc, const char *con_id,
unsigned long lflags, enum gpiod_flags dflags);
int gpio_set_debounce_timeout(struct gpio_desc *desc, unsigned int debounce);
int gpiod_hog(struct gpio_desc *desc, const char *name,
unsigned long lflags, enum gpiod_flags dflags);
int gpiochip_get_ngpios(struct gpio_chip *gc, struct device *dev);
/*
* Return the GPIO number of the passed descriptor relative to its chip
*/
static inline int gpio_chip_hwgpio(const struct gpio_desc *desc)
{
return desc - &desc->gdev->descs[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(gc, fmt, ...) \
dev_emerg(&gc->gpiodev->dev, "(%s): " fmt, gc->label, ##__VA_ARGS__)
#define chip_crit(gc, fmt, ...) \
dev_crit(&gc->gpiodev->dev, "(%s): " fmt, gc->label, ##__VA_ARGS__)
#define chip_err(gc, fmt, ...) \
dev_err(&gc->gpiodev->dev, "(%s): " fmt, gc->label, ##__VA_ARGS__)
#define chip_warn(gc, fmt, ...) \
dev_warn(&gc->gpiodev->dev, "(%s): " fmt, gc->label, ##__VA_ARGS__)
#define chip_info(gc, fmt, ...) \
dev_info(&gc->gpiodev->dev, "(%s): " fmt, gc->label, ##__VA_ARGS__)
#define chip_dbg(gc, fmt, ...) \
dev_dbg(&gc->gpiodev->dev, "(%s): " fmt, gc->label, ##__VA_ARGS__)
#endif /* GPIOLIB_H */
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