linux/drivers/input/ff-core.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *  Force feedback support for Linux input subsystem
 *
 *  Copyright (c) 2006 Anssi Hannula <[email protected]>
 *  Copyright (c) 2006 Dmitry Torokhov <[email protected]>
 */

/* #define DEBUG */

#include <linux/input.h>
#include <linux/limits.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/overflow.h>
#include <linux/sched.h>
#include <linux/slab.h>

/*
 * Check that the effect_id is a valid effect and whether the user
 * is the owner
 */
static int check_effect_access(struct ff_device *ff, int effect_id,
				struct file *file)
{ … }

/*
 * Checks whether 2 effects can be combined together
 */
static inline int check_effects_compatible(struct ff_effect *e1,
					   struct ff_effect *e2)
{ … }

/*
 * Convert an effect into compatible one
 */
static int compat_effect(struct ff_device *ff, struct ff_effect *effect)
{ … }

/**
 * input_ff_upload() - upload effect into force-feedback device
 * @dev: input device
 * @effect: effect to be uploaded
 * @file: owner of the effect
 */
int input_ff_upload(struct input_dev *dev, struct ff_effect *effect,
		    struct file *file)
{ … }
EXPORT_SYMBOL_GPL(…);

/*
 * Erases the effect if the requester is also the effect owner. The mutex
 * should already be locked before calling this function.
 */
static int erase_effect(struct input_dev *dev, int effect_id,
			struct file *file)
{ … }

/**
 * input_ff_erase - erase a force-feedback effect from device
 * @dev: input device to erase effect from
 * @effect_id: id of the effect to be erased
 * @file: purported owner of the request
 *
 * This function erases a force-feedback effect from specified device.
 * The effect will only be erased if it was uploaded through the same
 * file handle that is requesting erase.
 */
int input_ff_erase(struct input_dev *dev, int effect_id, struct file *file)
{ … }
EXPORT_SYMBOL_GPL(…);

/*
 * input_ff_flush - erase all effects owned by a file handle
 * @dev: input device to erase effect from
 * @file: purported owner of the effects
 *
 * This function erases all force-feedback effects associated with
 * the given owner from specified device. Note that @file may be %NULL,
 * in which case all effects will be erased.
 */
int input_ff_flush(struct input_dev *dev, struct file *file)
{ … }
EXPORT_SYMBOL_GPL(…);

/**
 * input_ff_event() - generic handler for force-feedback events
 * @dev: input device to send the effect to
 * @type: event type (anything but EV_FF is ignored)
 * @code: event code
 * @value: event value
 */
int input_ff_event(struct input_dev *dev, unsigned int type,
		   unsigned int code, int value)
{ … }
EXPORT_SYMBOL_GPL(…);

/**
 * input_ff_create() - create force-feedback device
 * @dev: input device supporting force-feedback
 * @max_effects: maximum number of effects supported by the device
 *
 * This function allocates all necessary memory for a force feedback
 * portion of an input device and installs all default handlers.
 * @dev->ffbit should be already set up before calling this function.
 * Once ff device is created you need to setup its upload, erase,
 * playback and other handlers before registering input device
 */
int input_ff_create(struct input_dev *dev, unsigned int max_effects)
{ … }
EXPORT_SYMBOL_GPL(…);

/**
 * input_ff_destroy() - frees force feedback portion of input device
 * @dev: input device supporting force feedback
 *
 * This function is only needed in error path as input core will
 * automatically free force feedback structures when device is
 * destroyed.
 */
void input_ff_destroy(struct input_dev *dev)
{ … }
EXPORT_SYMBOL_GPL(…);