Added virtio_dma_map() to map DMA addresses for virtual memory in
advance. The purpose is to keep memory mapped across multiple add/get
buf operations.
Added virtio_dma_unmap() for unmap DMA address.
Signed-off-by: Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx>
---
drivers/virtio/virtio_ring.c | 92 ++++++++++++++++++++++++++++++++++++
include/linux/virtio.h | 9 ++++
2 files changed, 101 insertions(+)
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index cd9364eb2345..855338609c7f 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -3172,4 +3172,96 @@ const struct vring *virtqueue_get_vring(struct virtqueue *vq)
}
EXPORT_SYMBOL_GPL(virtqueue_get_vring);
+/**
+ * virtio_dma_map_page - get the DMA addr of the memory for virtio device
+ * @dev: virtio device
+ * @page: the page of the memory to DMA
+ * @offset: the offset of the memory inside page
+ * @length: memory length
+ * @dir: DMA direction
+ *
+ * This API is only for pre-mapped buffers, for non premapped buffers virtio
+ * core handles DMA API internally.
+ *
+ * Returns the DMA addr. DMA_MAPPING_ERROR means error.
+ */
+dma_addr_t virtio_dma_map_page(struct device *dev, struct page *page, size_t offset,
+ unsigned int length, enum dma_data_direction dir)
+{
+ struct virtio_device *vdev = dev_to_virtio(dev);
+
+ if (!vring_use_dma_api(vdev))
+ return page_to_phys(page) + offset;
+
+ return dma_map_page(vdev->dev.parent, page, offset, length, dir);
+}
+
+/**
+ * virtio_dma_map - get the DMA addr of the memory for virtio device
+ * @dev: virtio device
+ * @addr: the addr to DMA
+ * @length: memory length
+ * @dir: DMA direction
+ *
+ * This API is only for pre-mapped buffers, for non premapped buffers virtio
+ * core handles DMA API internally.
+ *
+ * Returns the DMA addr.
+ */
+dma_addr_t virtio_dma_map(struct device *dev, void *addr, unsigned int length,
+ enum dma_data_direction dir)
+{
+ struct page *page;
+ size_t offset;
+
+ page = virt_to_page(addr);
+ offset = offset_in_page(addr);
+
+ return virtio_dma_map_page(dev, page, offset, length, dir);
+}
+EXPORT_SYMBOL_GPL(virtio_dma_map);
+
+/**
+ * virtio_dma_mapping_error - check dma address
+ * @dev: virtio device
+ * @addr: DMA address
+ *
+ * This API is only for pre-mapped buffers, for non premapped buffers virtio
+ * core handles DMA API internally.
+ *
+ * Returns 0 means dma valid. Other means invalid dma address.
+ */
+int virtio_dma_mapping_error(struct device *dev, dma_addr_t addr)
+{
+ struct virtio_device *vdev = dev_to_virtio(dev);
+
+ if (!vring_use_dma_api(vdev))
+ return 0;
+
+ return dma_mapping_error(vdev->dev.parent, addr);
+}
+EXPORT_SYMBOL_GPL(virtio_dma_mapping_error);
+
+/**
+ * virtio_dma_unmap - unmap DMA addr
+ * @dev: virtio device
+ * @dma: DMA address
+ * @length: memory length
+ * @dir: DMA direction
+ *
+ * This API is only for pre-mapped buffers, for non premapped buffers virtio
+ * core handles DMA API internally.
+ */
+void virtio_dma_unmap(struct device *dev, dma_addr_t dma, unsigned int length,
+ enum dma_data_direction dir)
+{
+ struct virtio_device *vdev = dev_to_virtio(dev);
+
+ if (!vring_use_dma_api(vdev))
+ return;
+
+ dma_unmap_page(vdev->dev.parent, dma, length, dir);
+}
+EXPORT_SYMBOL_GPL(virtio_dma_unmap);
+
MODULE_LICENSE("GPL");
diff --git a/include/linux/virtio.h b/include/linux/virtio.h
index 3ebb346ebb7c..b5fa71476737 100644
--- a/include/linux/virtio.h
+++ b/include/linux/virtio.h
@@ -9,6 +9,7 @@
#include <linux/device.h>
#include <linux/mod_devicetable.h>
#include <linux/gfp.h>
+#include <linux/dma-mapping.h>
/**
* struct virtqueue - a queue to register buffers for sending or receiving.
@@ -216,4 +217,12 @@ void unregister_virtio_driver(struct virtio_driver *drv);
#define module_virtio_driver(__virtio_driver) \
module_driver(__virtio_driver, register_virtio_driver, \
unregister_virtio_driver)
+
+dma_addr_t virtio_dma_map_page(struct device *dev, struct page *page, size_t offset,
+ unsigned int length, enum dma_data_direction dir);
+dma_addr_t virtio_dma_map(struct device *dev, void *addr, unsigned int length,
+ enum dma_data_direction dir);
+int virtio_dma_mapping_error(struct device *dev, dma_addr_t addr);
+void virtio_dma_unmap(struct device *dev, dma_addr_t dma, unsigned int length,
+ enum dma_data_direction dir);
#endif /* _LINUX_VIRTIO_H */
--
2.32.0.3.g01195cf9f
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