usb: gadget: uvc: support zero copy with rockchip encoder

Some rockchip encoder (e.g RV1106/RV1103) support to reserve
UVC Header in the encoded image, this patch improve the uvc
driver to support zero copy for uvc formats MJPEG/H264/H265,
and no support zero copy for YUYV.

By default, the uvc driver disable the zero copy, you can
set the ${USB_FUNCTIONS_DIR}/uvc.gs*/uvc_zero_copy to 1
to enable the zero copy.

Signed-off-by: William Wu <william.wu@rock-chips.com>
Change-Id: I19be26170d51f209f3196f546515be665481b8b5

drivers/usb/gadget/function/u_uvc.h

@@ -30,6 +30,7 @@ struct f_uvc_opts {
 	bool						device_name_allocated;
 	const char					*device_name;
 	unsigned int					uvc_num_request;
+	unsigned int					uvc_zero_copy;
 #endif
 
 	unsigned int					control_interface;

drivers/usb/gadget/function/uvc_configfs.c

@@ -2769,6 +2769,7 @@ UVCG_OPTS_ATTR(streaming_maxburst, streaming_maxburst, 15);
 UVCG_OPTS_ATTR(pm_qos_latency, pm_qos_latency, PM_QOS_LATENCY_ANY);
 #if defined(CONFIG_ARCH_ROCKCHIP) && defined(CONFIG_NO_GKI)
 UVCG_OPTS_ATTR(uvc_num_request, uvc_num_request, 64);
+UVCG_OPTS_ATTR(uvc_zero_copy, uvc_zero_copy, 1);
 #endif
 
 #undef UVCG_OPTS_ATTR
@@ -2878,6 +2879,7 @@ static struct configfs_attribute *uvc_attrs[] = {
 #if defined(CONFIG_ARCH_ROCKCHIP) && defined(CONFIG_NO_GKI)
 	&f_uvc_opts_attr_device_name,
 	&f_uvc_opts_attr_uvc_num_request,
+	&f_uvc_opts_attr_uvc_zero_copy,
 #endif
 	&f_uvc_opts_string_attr_function_name,
 	NULL,

drivers/usb/gadget/function/uvc_queue.c

@@ -79,6 +79,72 @@ static int uvc_queue_setup(struct vb2_queue *vq,
 	return 0;
 }
 
+#if defined(CONFIG_ARCH_ROCKCHIP) && defined(CONFIG_NO_GKI)
+/*
+ * uvc_dma_buf_phys_to_virt - Get the physical address of the dma_buf and
+ * translate it to virtual address.
+ *
+ * @dbuf: the dma_buf of vb2_plane
+ * @dev: the device to the actual usb controller
+ *
+ * This function is used for dma buf allocated by Contiguous Memory Allocator.
+ *
+ * Returns:
+ * The virtual addresses of the dma_buf.
+ */
+static void *uvc_dma_buf_phys_to_virt(struct uvc_device *uvc,
+				      struct dma_buf *dbuf)
+{
+	struct usb_gadget *gadget = uvc->func.config->cdev->gadget;
+	struct dma_buf_attachment *attachment;
+	struct sg_table *table;
+	struct scatterlist *sgl;
+	dma_addr_t phys = 0;
+	int i;
+
+	attachment = dma_buf_attach(dbuf, gadget->dev.parent);
+	if (IS_ERR(attachment))
+		return ERR_PTR(-ENOMEM);
+
+	table = dma_buf_map_attachment(attachment, DMA_BIDIRECTIONAL);
+	if (IS_ERR(table)) {
+		dma_buf_detach(dbuf, attachment);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	for_each_sgtable_sg(table, sgl, i)
+		phys = sg_phys(sgl);
+
+	dma_buf_unmap_attachment(attachment, table, DMA_BIDIRECTIONAL);
+	dma_buf_detach(dbuf, attachment);
+
+	if (i > 1) {
+		uvcg_err(&uvc->func, "Not support mult sgl for uvc zero copy\n");
+		return ERR_PTR(-ENOMEM);
+	}
+
+	return phys_to_virt(phys);
+}
+
+static void *uvc_buffer_mem_prepare(struct vb2_buffer *vb,
+				    struct uvc_video_queue *queue)
+{
+	struct uvc_video *video = container_of(queue, struct uvc_video, queue);
+	struct uvc_device *uvc = container_of(video, struct uvc_device, video);
+	struct f_uvc_opts *opts = fi_to_f_uvc_opts(uvc->func.fi);
+	void *mem;
+
+	if (!opts->uvc_zero_copy || video->fcc == V4L2_PIX_FMT_YUYV)
+		return (vb2_plane_vaddr(vb, 0) + vb2_plane_data_offset(vb, 0));
+
+	mem = uvc_dma_buf_phys_to_virt(uvc, vb->planes[0].dbuf);
+	if (IS_ERR(mem))
+		return ERR_PTR(-ENOMEM);
+
+	return (mem + vb2_plane_data_offset(vb, 0));
+}
+#endif
+
 static int uvc_buffer_prepare(struct vb2_buffer *vb)
 {
 	struct uvc_video_queue *queue = vb2_get_drv_priv(vb->vb2_queue);
@@ -95,8 +161,10 @@ static int uvc_buffer_prepare(struct vb2_buffer *vb)
 		return -ENODEV;
 
 	buf->state = UVC_BUF_STATE_QUEUED;
-#ifdef CONFIG_ARCH_ROCKCHIP
-	buf->mem = vb2_plane_vaddr(vb, 0) + vb2_plane_data_offset(vb, 0);
+#if defined(CONFIG_ARCH_ROCKCHIP) && defined(CONFIG_NO_GKI)
+	buf->mem = uvc_buffer_mem_prepare(vb, queue);
+	if (IS_ERR(buf->mem))
+		return -ENOMEM;
 #else
 	buf->mem = vb2_plane_vaddr(vb, 0);
 #endif

drivers/usb/gadget/function/uvc_video.c

@@ -21,6 +21,24 @@
 #include "uvc_video.h"
 #include "u_uvc.h"
 
+#if defined(CONFIG_ARCH_ROCKCHIP) && defined(CONFIG_NO_GKI)
+static bool uvc_using_zero_copy(struct uvc_video *video)
+{
+	struct uvc_device *uvc = container_of(video, struct uvc_device, video);
+	struct f_uvc_opts *opts = fi_to_f_uvc_opts(uvc->func.fi);
+
+	if (opts && opts->uvc_zero_copy && video->fcc != V4L2_PIX_FMT_YUYV)
+		return true;
+	else
+		return false;
+}
+#else
+static inline bool uvc_using_zero_copy(struct uvc_video *video)
+{
+	return false;
+}
+#endif
+
 /* --------------------------------------------------------------------------
  * Video codecs
  */
@@ -29,6 +47,20 @@ static int
 uvc_video_encode_header(struct uvc_video *video, struct uvc_buffer *buf,
 		u8 *data, int len)
 {
+	if (uvc_using_zero_copy(video)) {
+		u8 *mem;
+
+		mem = buf->mem + video->queue.buf_used +
+		      (video->queue.buf_used / (video->req_size - 2)) * 2;
+
+		mem[0] = 2;
+		mem[1] = UVC_STREAM_EOH | video->fid;
+		if (buf->bytesused - video->queue.buf_used <= len - 2)
+			mem[1] |= UVC_STREAM_EOF;
+
+		return 2;
+	}
+
 	data[0] = 2;
 	data[1] = UVC_STREAM_EOH | video->fid;
 
@@ -50,7 +82,8 @@ uvc_video_encode_data(struct uvc_video *video, struct uvc_buffer *buf,
 	mem = buf->mem + queue->buf_used;
 	nbytes = min((unsigned int)len, buf->bytesused - queue->buf_used);
 
-	memcpy(data, mem, nbytes);
+	if (!uvc_using_zero_copy(video))
+		memcpy(data, mem, nbytes);
 	queue->buf_used += nbytes;
 
 	return nbytes;
@@ -105,6 +138,10 @@ uvc_video_encode_isoc(struct usb_request *req, struct uvc_video *video,
 	int len = video->req_size;
 	int ret;
 
+	if (uvc_using_zero_copy(video))
+		req->buf = buf->mem + video->queue.buf_used +
+			   (video->queue.buf_used / (video->req_size - 2)) * 2;
+
 	/* Add the header. */
 	ret = uvc_video_encode_header(video, buf, mem, len);
 	mem += ret;