[PATCH] swiotlb: support syncing sub-ranges of mappings

This patch implements swiotlb_sync_single_range_for_{cpu,device}. This
is intended to support an x86_64 implementation of
dma_sync_single_range_for_{cpu,device}.

Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>

2 files changed, 41 insertions, 0 deletions

diff --git a/include/asm-x86_64/swiotlb.h b/include/asm-x86_64/swiotlb.h
index 36293061f4ed..9b011dd8d19d 100644
--- a/include/asm-x86_64/swiotlb.h
+++ b/include/asm-x86_64/swiotlb.h
@@ -15,6 +15,14 @@ extern void swiotlb_sync_single_for_cpu(struct device *hwdev,
 extern void swiotlb_sync_single_for_device(struct device *hwdev,
                                             dma_addr_t dev_addr,
                                             size_t size, int dir);
+extern void swiotlb_sync_single_range_for_cpu(struct device *hwdev,
+                                              dma_addr_t dev_addr,
+                                              unsigned long offset,
+                                              size_t size, int dir);
+extern void swiotlb_sync_single_range_for_device(struct device *hwdev,
+                                                 dma_addr_t dev_addr,
+                                                 unsigned long offset,
+                                                 size_t size, int dir);
 extern void swiotlb_sync_sg_for_cpu(struct device *hwdev,
                                      struct scatterlist *sg, int nelems,
                                      int dir);
diff --git a/lib/swiotlb.c b/lib/swiotlb.c
index 9719a14649e7..566791b3f583 100644
--- a/lib/swiotlb.c
+++ b/lib/swiotlb.c
@@ -623,6 +623,37 @@ swiotlb_sync_single_for_device(struct device *hwdev, dma_addr_t dev_addr,
 }
 
 /*
+ * Same as above, but for a sub-range of the mapping.
+ */
+static inline void
+swiotlb_sync_single_range(struct device *hwdev, dma_addr_t dev_addr,
+                          unsigned long offset, size_t size, int dir)
+{
+        char *dma_addr = phys_to_virt(dev_addr) + offset;
+
+        if (dir == DMA_NONE)
+                BUG();
+        if (dma_addr >= io_tlb_start && dma_addr < io_tlb_end)
+                sync_single(hwdev, dma_addr, size, dir);
+        else if (dir == DMA_FROM_DEVICE)
+                mark_clean(dma_addr, size);
+}
+
+void
+swiotlb_sync_single_range_for_cpu(struct device *hwdev, dma_addr_t dev_addr,
+                                  unsigned long offset, size_t size, int dir)
+{
+        swiotlb_sync_single_range(hwdev, dev_addr, offset, size, dir);
+}
+
+void
+swiotlb_sync_single_range_for_device(struct device *hwdev, dma_addr_t dev_addr,
+                                     unsigned long offset, size_t size, int dir)
+{
+        swiotlb_sync_single_range(hwdev, dev_addr, offset, size, dir);
+}
+
+/*
  * Map a set of buffers described by scatterlist in streaming mode for DMA.
  * This is the scatter-gather version of the above swiotlb_map_single
  * interface.  Here the scatter gather list elements are each tagged with the
@@ -750,6 +781,8 @@ EXPORT_SYMBOL(swiotlb_map_sg);
 EXPORT_SYMBOL(swiotlb_unmap_sg);
 EXPORT_SYMBOL(swiotlb_sync_single_for_cpu);
 EXPORT_SYMBOL(swiotlb_sync_single_for_device);
+EXPORT_SYMBOL_GPL(swiotlb_sync_single_range_for_cpu);
+EXPORT_SYMBOL_GPL(swiotlb_sync_single_range_for_device);
 EXPORT_SYMBOL(swiotlb_sync_sg_for_cpu);
 EXPORT_SYMBOL(swiotlb_sync_sg_for_device);
 EXPORT_SYMBOL(swiotlb_dma_mapping_error);