linux/drivers/usb/gadget/function/uvc_queue.c

// SPDX-License-Identifier: GPL-2.0+
/*
 *	uvc_queue.c  --  USB Video Class driver - Buffers management
 *
 *	Copyright (C) 2005-2010
 *	    Laurent Pinchart ([email protected])
 */

#include <linux/atomic.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/usb.h>
#include <linux/videodev2.h>
#include <linux/vmalloc.h>
#include <linux/wait.h>

#include <media/v4l2-common.h>
#include <media/videobuf2-dma-sg.h>
#include <media/videobuf2-vmalloc.h>

#include "uvc.h"

/* ------------------------------------------------------------------------
 * Video buffers queue management.
 *
 * Video queues is initialized by uvcg_queue_init(). The function performs
 * basic initialization of the uvc_video_queue struct and never fails.
 *
 * Video buffers are managed by videobuf2. The driver uses a mutex to protect
 * the videobuf2 queue operations by serializing calls to videobuf2 and a
 * spinlock to protect the IRQ queue that holds the buffers to be processed by
 * the driver.
 */

/* -----------------------------------------------------------------------------
 * videobuf2 queue operations
 */

static int uvc_queue_setup(struct vb2_queue *vq,
			   unsigned int *nbuffers, unsigned int *nplanes,
			   unsigned int sizes[], struct device *alloc_devs[])
{ … }

static int uvc_buffer_prepare(struct vb2_buffer *vb)
{ … }

static void uvc_buffer_queue(struct vb2_buffer *vb)
{ … }

static const struct vb2_ops uvc_queue_qops = …;

int uvcg_queue_init(struct uvc_video_queue *queue, struct device *dev, enum v4l2_buf_type type,
		    struct mutex *lock)
{ … }

/*
 * Free the video buffers.
 */
void uvcg_free_buffers(struct uvc_video_queue *queue)
{ … }

/*
 * Allocate the video buffers.
 */
int uvcg_alloc_buffers(struct uvc_video_queue *queue,
			      struct v4l2_requestbuffers *rb)
{ … }

int uvcg_query_buffer(struct uvc_video_queue *queue, struct v4l2_buffer *buf)
{ … }

int uvcg_queue_buffer(struct uvc_video_queue *queue, struct v4l2_buffer *buf)
{ … }

/*
 * Dequeue a video buffer. If nonblocking is false, block until a buffer is
 * available.
 */
int uvcg_dequeue_buffer(struct uvc_video_queue *queue, struct v4l2_buffer *buf,
			int nonblocking)
{ … }

/*
 * Poll the video queue.
 *
 * This function implements video queue polling and is intended to be used by
 * the device poll handler.
 */
__poll_t uvcg_queue_poll(struct uvc_video_queue *queue, struct file *file,
			     poll_table *wait)
{ … }

int uvcg_queue_mmap(struct uvc_video_queue *queue, struct vm_area_struct *vma)
{ … }

#ifndef CONFIG_MMU
/*
 * Get unmapped area.
 *
 * NO-MMU arch need this function to make mmap() work correctly.
 */
unsigned long uvcg_queue_get_unmapped_area(struct uvc_video_queue *queue,
					   unsigned long pgoff)
{
	return vb2_get_unmapped_area(&queue->queue, 0, 0, pgoff, 0);
}
#endif

/*
 * Cancel the video buffers queue.
 *
 * Cancelling the queue marks all buffers on the irq queue as erroneous,
 * wakes them up and removes them from the queue.
 *
 * If the disconnect parameter is set, further calls to uvc_queue_buffer will
 * fail with -ENODEV.
 *
 * This function acquires the irq spinlock and can be called from interrupt
 * context.
 */
void uvcg_queue_cancel(struct uvc_video_queue *queue, int disconnect)
{ … }

/*
 * Enable or disable the video buffers queue.
 *
 * The queue must be enabled before starting video acquisition and must be
 * disabled after stopping it. This ensures that the video buffers queue
 * state can be properly initialized before buffers are accessed from the
 * interrupt handler.
 *
 * Enabling the video queue initializes parameters (such as sequence number,
 * sync pattern, ...). If the queue is already enabled, return -EBUSY.
 *
 * Disabling the video queue cancels the queue and removes all buffers from
 * the main queue.
 *
 * This function can't be called from interrupt context. Use
 * uvcg_queue_cancel() instead.
 */
int uvcg_queue_enable(struct uvc_video_queue *queue, int enable)
{ … }

/* called with &queue_irqlock held.. */
void uvcg_complete_buffer(struct uvc_video_queue *queue,
					  struct uvc_buffer *buf)
{ … }

struct uvc_buffer *uvcg_queue_head(struct uvc_video_queue *queue)
{ … }