1 files changed, 386 insertions, 0 deletions

diff --git a/drivers/usb/gadget/uvc_video.c b/drivers/usb/gadget/uvc_video.c
new file mode 100644
index 000000000000..de8cbc46518d
--- /dev/null
+++ b/drivers/usb/gadget/uvc_video.c
@@ -0,0 +1,386 @@
+/*
+ *      uvc_video.c  --  USB Video Class Gadget driver
+ *
+ *      Copyright (C) 2009-2010
+ *          Laurent Pinchart (laurent.pinchart@ideasonboard.com)
+ *
+ *      This program is free software; you can redistribute it and/or modify
+ *      it under the terms of the GNU General Public License as published by
+ *      the Free Software Foundation; either version 2 of the License, or
+ *      (at your option) any later version.
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/device.h>
+#include <linux/errno.h>
+#include <linux/usb/ch9.h>
+#include <linux/usb/gadget.h>
+
+#include <media/v4l2-dev.h>
+
+#include "uvc.h"
+#include "uvc_queue.h"
+
+/* --------------------------------------------------------------------------
+ * Video codecs
+ */
+
+static int
+uvc_video_encode_header(struct uvc_video *video, struct uvc_buffer *buf,
+                u8 *data, int len)
+{
+        data[0] = 2;
+        data[1] = UVC_STREAM_EOH | video->fid;
+
+        if (buf->buf.bytesused - video->queue.buf_used <= len - 2)
+                data[1] |= UVC_STREAM_EOF;
+
+        return 2;
+}
+
+static int
+uvc_video_encode_data(struct uvc_video *video, struct uvc_buffer *buf,
+                u8 *data, int len)
+{
+        struct uvc_video_queue *queue = &video->queue;
+        unsigned int nbytes;
+        void *mem;
+
+        /* Copy video data to the USB buffer. */
+        mem = queue->mem + buf->buf.m.offset + queue->buf_used;
+        nbytes = min((unsigned int)len, buf->buf.bytesused - queue->buf_used);
+
+        memcpy(data, mem, nbytes);
+        queue->buf_used += nbytes;
+
+        return nbytes;
+}
+
+static void
+uvc_video_encode_bulk(struct usb_request *req, struct uvc_video *video,
+                struct uvc_buffer *buf)
+{
+        void *mem = req->buf;
+        int len = video->req_size;
+        int ret;
+
+        /* Add a header at the beginning of the payload. */
+        if (video->payload_size == 0) {
+                ret = uvc_video_encode_header(video, buf, mem, len);
+                video->payload_size += ret;
+                mem += ret;
+                len -= ret;
+        }
+
+        /* Process video data. */
+        len = min((int)(video->max_payload_size - video->payload_size), len);
+        ret = uvc_video_encode_data(video, buf, mem, len);
+
+        video->payload_size += ret;
+        len -= ret;
+
+        req->length = video->req_size - len;
+        req->zero = video->payload_size == video->max_payload_size;
+
+        if (buf->buf.bytesused == video->queue.buf_used) {
+                video->queue.buf_used = 0;
+                buf->state = UVC_BUF_STATE_DONE;
+                uvc_queue_next_buffer(&video->queue, buf);
+                video->fid ^= UVC_STREAM_FID;
+
+                video->payload_size = 0;
+        }
+
+        if (video->payload_size == video->max_payload_size ||
+            buf->buf.bytesused == video->queue.buf_used)
+                video->payload_size = 0;
+}
+
+static void
+uvc_video_encode_isoc(struct usb_request *req, struct uvc_video *video,
+                struct uvc_buffer *buf)
+{
+        void *mem = req->buf;
+        int len = video->req_size;
+        int ret;
+
+        /* Add the header. */
+        ret = uvc_video_encode_header(video, buf, mem, len);
+        mem += ret;
+        len -= ret;
+
+        /* Process video data. */
+        ret = uvc_video_encode_data(video, buf, mem, len);
+        len -= ret;
+
+        req->length = video->req_size - len;
+
+        if (buf->buf.bytesused == video->queue.buf_used) {
+                video->queue.buf_used = 0;
+                buf->state = UVC_BUF_STATE_DONE;
+                uvc_queue_next_buffer(&video->queue, buf);
+                video->fid ^= UVC_STREAM_FID;
+        }
+}
+
+/* --------------------------------------------------------------------------
+ * Request handling
+ */
+
+/*
+ * I somehow feel that synchronisation won't be easy to achieve here. We have
+ * three events that control USB requests submission:
+ *
+ * - USB request completion: the completion handler will resubmit the request
+ *   if a video buffer is available.
+ *
+ * - USB interface setting selection: in response to a SET_INTERFACE request,
+ *   the handler will start streaming if a video buffer is available and if
+ *   video is not currently streaming.
+ *
+ * - V4L2 buffer queueing: the driver will start streaming if video is not
+ *   currently streaming.
+ *
+ * Race conditions between those 3 events might lead to deadlocks or other
+ * nasty side effects.
+ *
+ * The "video currently streaming" condition can't be detected by the irqqueue
+ * being empty, as a request can still be in flight. A separate "queue paused"
+ * flag is thus needed.
+ *
+ * The paused flag will be set when we try to retrieve the irqqueue head if the
+ * queue is empty, and cleared when we queue a buffer.
+ *
+ * The USB request completion handler will get the buffer at the irqqueue head
+ * under protection of the queue spinlock. If the queue is empty, the streaming
+ * paused flag will be set. Right after releasing the spinlock a userspace
+ * application can queue a buffer. The flag will then cleared, and the ioctl
+ * handler will restart the video stream.
+ */
+static void
+uvc_video_complete(struct usb_ep *ep, struct usb_request *req)
+{
+        struct uvc_video *video = req->context;
+        struct uvc_buffer *buf;
+        unsigned long flags;
+        int ret;
+
+        switch (req->status) {
+        case 0:
+                break;
+
+        case -ESHUTDOWN:
+                printk(KERN_INFO "VS request cancelled.\n");
+                goto requeue;
+
+        default:
+                printk(KERN_INFO "VS request completed with status %d.\n",
+                        req->status);
+                goto requeue;
+        }
+
+        spin_lock_irqsave(&video->queue.irqlock, flags);
+        buf = uvc_queue_head(&video->queue);
+        if (buf == NULL) {
+                spin_unlock_irqrestore(&video->queue.irqlock, flags);
+                goto requeue;
+        }
+
+        video->encode(req, video, buf);
+
+        if ((ret = usb_ep_queue(ep, req, GFP_ATOMIC)) < 0) {
+                printk(KERN_INFO "Failed to queue request (%d).\n", ret);
+                usb_ep_set_halt(ep);
+                spin_unlock_irqrestore(&video->queue.irqlock, flags);
+                goto requeue;
+        }
+        spin_unlock_irqrestore(&video->queue.irqlock, flags);
+
+        return;
+
+requeue:
+        spin_lock_irqsave(&video->req_lock, flags);
+        list_add_tail(&req->list, &video->req_free);
+        spin_unlock_irqrestore(&video->req_lock, flags);
+}
+
+static int
+uvc_video_free_requests(struct uvc_video *video)
+{
+        unsigned int i;
+
+        for (i = 0; i < UVC_NUM_REQUESTS; ++i) {
+                if (video->req[i]) {
+                        usb_ep_free_request(video->ep, video->req[i]);
+                        video->req[i] = NULL;
+                }
+
+                if (video->req_buffer[i]) {
+                        kfree(video->req_buffer[i]);
+                        video->req_buffer[i] = NULL;
+                }
+        }
+
+        INIT_LIST_HEAD(&video->req_free);
+        video->req_size = 0;
+        return 0;
+}
+
+static int
+uvc_video_alloc_requests(struct uvc_video *video)
+{
+        unsigned int i;
+        int ret = -ENOMEM;
+
+        BUG_ON(video->req_size);
+
+        for (i = 0; i < UVC_NUM_REQUESTS; ++i) {
+                video->req_buffer[i] = kmalloc(video->ep->maxpacket, GFP_KERNEL);
+                if (video->req_buffer[i] == NULL)
+                        goto error;
+
+                video->req[i] = usb_ep_alloc_request(video->ep, GFP_KERNEL);
+                if (video->req[i] == NULL)
+                        goto error;
+
+                video->req[i]->buf = video->req_buffer[i];
+                video->req[i]->length = 0;
+                video->req[i]->dma = DMA_ADDR_INVALID;
+                video->req[i]->complete = uvc_video_complete;
+                video->req[i]->context = video;
+
+                list_add_tail(&video->req[i]->list, &video->req_free);
+        }
+
+        video->req_size = video->ep->maxpacket;
+        return 0;
+
+error:
+        uvc_video_free_requests(video);
+        return ret;
+}
+
+/* --------------------------------------------------------------------------
+ * Video streaming
+ */
+
+/*
+ * uvc_video_pump - Pump video data into the USB requests
+ *
+ * This function fills the available USB requests (listed in req_free) with
+ * video data from the queued buffers.
+ */
+int
+uvc_video_pump(struct uvc_video *video)
+{
+        struct usb_request *req;
+        struct uvc_buffer *buf;
+        unsigned long flags;
+        int ret;
+
+        /* FIXME TODO Race between uvc_video_pump and requests completion
+         * handler ???
+         */
+
+        while (1) {
+                /* Retrieve the first available USB request, protected by the
+                 * request lock.
+                 */
+                spin_lock_irqsave(&video->req_lock, flags);
+                if (list_empty(&video->req_free)) {
+                        spin_unlock_irqrestore(&video->req_lock, flags);
+                        return 0;
+                }
+                req = list_first_entry(&video->req_free, struct usb_request,
+                                        list);
+                list_del(&req->list);
+                spin_unlock_irqrestore(&video->req_lock, flags);
+
+                /* Retrieve the first available video buffer and fill the
+                 * request, protected by the video queue irqlock.
+                 */
+                spin_lock_irqsave(&video->queue.irqlock, flags);
+                buf = uvc_queue_head(&video->queue);
+                if (buf == NULL) {
+                        spin_unlock_irqrestore(&video->queue.irqlock, flags);
+                        break;
+                }
+
+                video->encode(req, video, buf);
+
+                /* Queue the USB request */
+                if ((ret = usb_ep_queue(video->ep, req, GFP_KERNEL)) < 0) {
+                        printk(KERN_INFO "Failed to queue request (%d)\n", ret);
+                        usb_ep_set_halt(video->ep);
+                        spin_unlock_irqrestore(&video->queue.irqlock, flags);
+                        break;
+                }
+                spin_unlock_irqrestore(&video->queue.irqlock, flags);
+        }
+
+        spin_lock_irqsave(&video->req_lock, flags);
+        list_add_tail(&req->list, &video->req_free);
+        spin_unlock_irqrestore(&video->req_lock, flags);
+        return 0;
+}
+
+/*
+ * Enable or disable the video stream.
+ */
+int
+uvc_video_enable(struct uvc_video *video, int enable)
+{
+        unsigned int i;
+        int ret;
+
+        if (video->ep == NULL) {
+                printk(KERN_INFO "Video enable failed, device is "
+                        "uninitialized.\n");
+                return -ENODEV;
+        }
+
+        if (!enable) {
+                for (i = 0; i < UVC_NUM_REQUESTS; ++i)
+                        usb_ep_dequeue(video->ep, video->req[i]);
+
+                uvc_video_free_requests(video);
+                uvc_queue_enable(&video->queue, 0);
+                return 0;
+        }
+
+        if ((ret = uvc_queue_enable(&video->queue, 1)) < 0)
+                return ret;
+
+        if ((ret = uvc_video_alloc_requests(video)) < 0)
+                return ret;
+
+        if (video->max_payload_size) {
+                video->encode = uvc_video_encode_bulk;
+                video->payload_size = 0;
+        } else
+                video->encode = uvc_video_encode_isoc;
+
+        return uvc_video_pump(video);
+}
+
+/*
+ * Initialize the UVC video stream.
+ */
+int
+uvc_video_init(struct uvc_video *video)
+{
+        INIT_LIST_HEAD(&video->req_free);
+        spin_lock_init(&video->req_lock);
+
+        video->fcc = V4L2_PIX_FMT_YUYV;
+        video->bpp = 16;
+        video->width = 320;
+        video->height = 240;
+        video->imagesize = 320 * 240 * 2;
+
+        /* Initialize the video buffers queue. */
+        uvc_queue_init(&video->queue, V4L2_BUF_TYPE_VIDEO_OUTPUT);
+        return 0;
+}
+