USB gadget: video class function driver

This USB video class function driver implements a video capture device from the
host's point of view. It creates a V4L2 output device on the gadget's side to
transfer data from a userspace application over USB.

The UVC-specific descriptors are passed by the gadget driver to the UVC
function driver, making them completely configurable without any modification
to the function's driver code.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 89 insertions, 0 deletions

diff --git a/drivers/usb/gadget/uvc_queue.h b/drivers/usb/gadget/uvc_queue.h
new file mode 100644
index 000000000000..7f5a33fe7ae2
--- /dev/null
+++ b/drivers/usb/gadget/uvc_queue.h
@@ -0,0 +1,89 @@
+#ifndef _UVC_QUEUE_H_
+#define _UVC_QUEUE_H_
+
+#ifdef __KERNEL__
+
+#include <linux/kernel.h>
+#include <linux/poll.h>
+#include <linux/videodev2.h>
+
+/* Maximum frame size in bytes, for sanity checking. */
+#define UVC_MAX_FRAME_SIZE      (16*1024*1024)
+/* Maximum number of video buffers. */
+#define UVC_MAX_VIDEO_BUFFERS   32
+
+/* ------------------------------------------------------------------------
+ * Structures.
+ */
+
+enum uvc_buffer_state {
+        UVC_BUF_STATE_IDLE      = 0,
+        UVC_BUF_STATE_QUEUED    = 1,
+        UVC_BUF_STATE_ACTIVE    = 2,
+        UVC_BUF_STATE_DONE      = 3,
+        UVC_BUF_STATE_ERROR     = 4,
+};
+
+struct uvc_buffer {
+        unsigned long vma_use_count;
+        struct list_head stream;
+
+        /* Touched by interrupt handler. */
+        struct v4l2_buffer buf;
+        struct list_head queue;
+        wait_queue_head_t wait;
+        enum uvc_buffer_state state;
+};
+
+#define UVC_QUEUE_STREAMING             (1 << 0)
+#define UVC_QUEUE_DISCONNECTED          (1 << 1)
+#define UVC_QUEUE_DROP_INCOMPLETE       (1 << 2)
+#define UVC_QUEUE_PAUSED                (1 << 3)
+
+struct uvc_video_queue {
+        enum v4l2_buf_type type;
+
+        void *mem;
+        unsigned int flags;
+        __u32 sequence;
+
+        unsigned int count;
+        unsigned int buf_size;
+        unsigned int buf_used;
+        struct uvc_buffer buffer[UVC_MAX_VIDEO_BUFFERS];
+        struct mutex mutex;     /* protects buffers and mainqueue */
+        spinlock_t irqlock;     /* protects irqqueue */
+
+        struct list_head mainqueue;
+        struct list_head irqqueue;
+};
+
+extern void uvc_queue_init(struct uvc_video_queue *queue,
+                enum v4l2_buf_type type);
+extern int uvc_alloc_buffers(struct uvc_video_queue *queue,
+                unsigned int nbuffers, unsigned int buflength);
+extern int uvc_free_buffers(struct uvc_video_queue *queue);
+extern int uvc_query_buffer(struct uvc_video_queue *queue,
+                struct v4l2_buffer *v4l2_buf);
+extern int uvc_queue_buffer(struct uvc_video_queue *queue,
+                struct v4l2_buffer *v4l2_buf);
+extern int uvc_dequeue_buffer(struct uvc_video_queue *queue,
+                struct v4l2_buffer *v4l2_buf, int nonblocking);
+extern int uvc_queue_enable(struct uvc_video_queue *queue, int enable);
+extern void uvc_queue_cancel(struct uvc_video_queue *queue, int disconnect);
+extern struct uvc_buffer *uvc_queue_next_buffer(struct uvc_video_queue *queue,
+                struct uvc_buffer *buf);
+extern unsigned int uvc_queue_poll(struct uvc_video_queue *queue,
+                struct file *file, poll_table *wait);
+extern int uvc_queue_mmap(struct uvc_video_queue *queue,
+                struct vm_area_struct *vma);
+static inline int uvc_queue_streaming(struct uvc_video_queue *queue)
+{
+        return queue->flags & UVC_QUEUE_STREAMING;
+}
+extern struct uvc_buffer *uvc_queue_head(struct uvc_video_queue *queue);
+
+#endif /* __KERNEL__ */
+
+#endif /* _UVC_QUEUE_H_ */
+