V4L/DVB (6058): ivtv: add support for highmem udma

When trying to DMA userspace buffers to the cx23415 you need to check
whether the page is in highmem. If this is the case, then bounce buffers
have to be used to allow DMA.
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>

drivers/media/video/ivtv/ivtv-driver.h

@@ -419,6 +419,8 @@ struct ivtv_user_dma {
 	struct mutex lock;
 	int page_count;
 	struct page *map[IVTV_DMA_SG_OSD_ENT];
+	/* Needed when dealing with highmem userspace buffers */
+	struct page *bouncemap[IVTV_DMA_SG_OSD_ENT];
 
 	/* Base Dev SG Array for cx23415/6 */
 	struct ivtv_sg_element SGarray[IVTV_DMA_SG_OSD_ENT];

drivers/media/video/ivtv/ivtv-udma.c

@@ -38,23 +38,38 @@ void ivtv_udma_get_page_info(struct ivtv_dma_page_info *dma_page, unsigned long
 int ivtv_udma_fill_sg_list (struct ivtv_user_dma *dma, struct ivtv_dma_page_info *dma_page, int map_offset)
 {
 	int i, offset;
+	unsigned long flags;
 
 	offset = dma_page->offset;
 
 	/* Fill SG Array with new values */
 	for (i = 0; i < dma_page->page_count; i++) {
-		if (i == dma_page->page_count - 1) {
-			dma->SGlist[map_offset].length = dma_page->tail;
+		unsigned int len = (i == dma_page->page_count - 1) ?
+			dma_page->tail : PAGE_SIZE - offset;
+
+		dma->SGlist[map_offset].length = len;
+		dma->SGlist[map_offset].offset = offset;
+		if (PageHighMem(dma->map[map_offset])) {
+			void *src;
+
+			if (dma->bouncemap[map_offset] == NULL)
+				dma->bouncemap[map_offset] = alloc_page(GFP_KERNEL);
+			if (dma->bouncemap[map_offset] == NULL)
+				return -ENOMEM;
+			local_irq_save(flags);
+			src = kmap_atomic(dma->map[map_offset], KM_BOUNCE_READ) + offset;
+			memcpy(page_address(dma->bouncemap[map_offset]) + offset, src, len);
+			kunmap_atomic(src, KM_BOUNCE_READ);
+			local_irq_restore(flags);
+			dma->SGlist[map_offset].page = dma->bouncemap[map_offset];
 		}
 		else {
-			dma->SGlist[map_offset].length = PAGE_SIZE - offset;
+			dma->SGlist[map_offset].page = dma->map[map_offset];
 		}
-		dma->SGlist[map_offset].offset = offset;
-		dma->SGlist[map_offset].page = dma->map[map_offset];
 		offset = 0;
 		map_offset++;
 	}
-	return map_offset;
+	return 0;
 }
 
 void ivtv_udma_fill_sg_array (struct ivtv_user_dma *dma, u32 buffer_offset, u32 buffer_offset_2, u32 split) {
@@ -89,7 +104,7 @@ int ivtv_udma_setup(struct ivtv *itv, unsigned long ivtv_dest_addr,
 {
 	struct ivtv_dma_page_info user_dma;
 	struct ivtv_user_dma *dma = &itv->udma;
-	int err;
+	int i, err;
 
 	IVTV_DEBUG_DMA("ivtv_udma_setup, dst: 0x%08x\n", (unsigned int)ivtv_dest_addr);
 
@@ -123,7 +138,14 @@ int ivtv_udma_setup(struct ivtv *itv, unsigned long ivtv_dest_addr,
 	dma->page_count = user_dma.page_count;
 
 	/* Fill SG List with new values */
-	ivtv_udma_fill_sg_list(dma, &user_dma, 0);
+	err = ivtv_udma_fill_sg_list(dma, &user_dma, 0);
+	if (err) {
+		for (i = 0; i < dma->page_count; i++) {
+			put_page(dma->map[i]);
+		}
+		dma->page_count = 0;
+		return err;
+	}
 
 	/* Map SG List */
 	dma->SG_length = pci_map_sg(itv->dev, dma->SGlist, dma->page_count, PCI_DMA_TODEVICE);
@@ -166,6 +188,8 @@ void ivtv_udma_unmap(struct ivtv *itv)
 
 void ivtv_udma_free(struct ivtv *itv)
 {
+	int i;
+
 	/* Unmap SG Array */
 	if (itv->udma.SG_handle) {
 		pci_unmap_single(itv->dev, itv->udma.SG_handle,
@@ -176,6 +200,11 @@ void ivtv_udma_free(struct ivtv *itv)
 	if (itv->udma.SG_length) {
 		pci_unmap_sg(itv->dev, itv->udma.SGlist, itv->udma.page_count, PCI_DMA_TODEVICE);
 	}
+
+	for (i = 0; i < IVTV_DMA_SG_OSD_ENT; i++) {
+		if (itv->udma.bouncemap[i])
+			__free_page(itv->udma.bouncemap[i]);
+	}
 }
 
 void ivtv_udma_start(struct ivtv *itv)

drivers/media/video/ivtv/ivtv-yuv.c

@@ -83,7 +83,14 @@ static int ivtv_yuv_prep_user_dma(struct ivtv *itv, struct ivtv_user_dma *dma,
 	}
 
 	/* Fill & map SG List */
-	ivtv_udma_fill_sg_list (dma, &uv_dma, ivtv_udma_fill_sg_list (dma, &y_dma, 0));
+	if (ivtv_udma_fill_sg_list (dma, &uv_dma, ivtv_udma_fill_sg_list (dma, &y_dma, 0))) {
+		IVTV_DEBUG_WARN("could not allocate bounce buffers for highmem userspace buffers\n");
+		for (i = 0; i < dma->page_count; i++) {
+			put_page(dma->map[i]);
+		}
+		dma->page_count = 0;
+		return -ENOMEM;
+	}
 	dma->SG_length = pci_map_sg(itv->dev, dma->SGlist, dma->page_count, PCI_DMA_TODEVICE);
 
 	/* Fill SG Array with new values */