swiotlb: add support for systems with highmem
Impact: extend code for highmem - existing users unaffected
On highmem systems, the original dma buffer might not
have a virtual mapping - we need to kmap it in to perform
the bounce. Extract the code that does the actual
copy into a function that does the kmap if highmem
is enabled, and default to the normal swiotlb memcpy
if not.
[ ported by Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> ]
Signed-off-by: Becky Bruce <beckyb@kernel.crashing.org>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/lib/swiotlb.c b/lib/swiotlb.c
index 98a7a44..785046e 100644
--- a/lib/swiotlb.c
+++ b/lib/swiotlb.c
@@ -14,6 +14,7 @@
* 04/07/.. ak Better overflow handling. Assorted fixes.
* 05/09/10 linville Add support for syncing ranges, support syncing for
* DMA_BIDIRECTIONAL mappings, miscellaneous cleanup.
+ * 08/12/11 beckyb Add highmem support
*/
#include <linux/cache.h>
@@ -24,6 +25,7 @@
#include <linux/swiotlb.h>
#include <linux/string.h>
#include <linux/swiotlb.h>
+#include <linux/pfn.h>
#include <linux/types.h>
#include <linux/ctype.h>
#include <linux/highmem.h>
@@ -149,11 +151,6 @@
return 0;
}
-static dma_addr_t swiotlb_sg_to_bus(struct device *hwdev, struct scatterlist *sg)
-{
- return swiotlb_phys_to_bus(hwdev, page_to_phys(sg_page(sg)) + sg->offset);
-}
-
static void swiotlb_print_info(unsigned long bytes)
{
phys_addr_t pstart, pend;
@@ -330,6 +327,47 @@
}
/*
+ * Bounce: copy the swiotlb buffer back to the original dma location
+ */
+static void swiotlb_bounce(phys_addr_t phys, char *dma_addr, size_t size,
+ enum dma_data_direction dir)
+{
+ unsigned long pfn = PFN_DOWN(phys);
+
+ if (PageHighMem(pfn_to_page(pfn))) {
+ /* The buffer does not have a mapping. Map it in and copy */
+ unsigned int offset = phys & ~PAGE_MASK;
+ char *buffer;
+ unsigned int sz = 0;
+ unsigned long flags;
+
+ while (size) {
+ sz = min(PAGE_SIZE - offset, size);
+
+ local_irq_save(flags);
+ buffer = kmap_atomic(pfn_to_page(pfn),
+ KM_BOUNCE_READ);
+ if (dir == DMA_TO_DEVICE)
+ memcpy(dma_addr, buffer + offset, sz);
+ else
+ memcpy(buffer + offset, dma_addr, sz);
+ kunmap_atomic(buffer, KM_BOUNCE_READ);
+ local_irq_restore(flags);
+
+ size -= sz;
+ pfn++;
+ dma_addr += sz;
+ offset = 0;
+ }
+ } else {
+ if (dir == DMA_TO_DEVICE)
+ memcpy(dma_addr, phys_to_virt(phys), size);
+ else
+ memcpy(phys_to_virt(phys), dma_addr, size);
+ }
+}
+
+/*
* Allocates bounce buffer and returns its kernel virtual address.
*/
static void *
@@ -430,7 +468,7 @@
for (i = 0; i < nslots; i++)
io_tlb_orig_addr[index+i] = phys + (i << IO_TLB_SHIFT);
if (dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL)
- memcpy(dma_addr, phys_to_virt(phys), size);
+ swiotlb_bounce(phys, dma_addr, size, DMA_TO_DEVICE);
return dma_addr;
}
@@ -450,11 +488,7 @@
* First, sync the memory before unmapping the entry
*/
if (phys && ((dir == DMA_FROM_DEVICE) || (dir == DMA_BIDIRECTIONAL)))
- /*
- * bounce... copy the data back into the original buffer * and
- * delete the bounce buffer.
- */
- memcpy(phys_to_virt(phys), dma_addr, size);
+ swiotlb_bounce(phys, dma_addr, size, DMA_FROM_DEVICE);
/*
* Return the buffer to the free list by setting the corresponding
@@ -494,13 +528,13 @@
switch (target) {
case SYNC_FOR_CPU:
if (likely(dir == DMA_FROM_DEVICE || dir == DMA_BIDIRECTIONAL))
- memcpy(phys_to_virt(phys), dma_addr, size);
+ swiotlb_bounce(phys, dma_addr, size, DMA_FROM_DEVICE);
else
BUG_ON(dir != DMA_TO_DEVICE);
break;
case SYNC_FOR_DEVICE:
if (likely(dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL))
- memcpy(dma_addr, phys_to_virt(phys), size);
+ swiotlb_bounce(phys, dma_addr, size, DMA_TO_DEVICE);
else
BUG_ON(dir != DMA_FROM_DEVICE);
break;
@@ -817,11 +851,11 @@
BUG_ON(dir == DMA_NONE);
for_each_sg(sgl, sg, nelems, i) {
- if (sg->dma_address != swiotlb_sg_to_bus(hwdev, sg))
+ if (sg->dma_address != swiotlb_virt_to_bus(hwdev, sg_virt(sg)))
unmap_single(hwdev, swiotlb_bus_to_virt(sg->dma_address),
sg->dma_length, dir);
else if (dir == DMA_FROM_DEVICE)
- dma_mark_clean(swiotlb_bus_to_virt(sg->dma_address), sg->dma_length);
+ dma_mark_clean(sg_virt(sg), sg->dma_length);
}
}
EXPORT_SYMBOL(swiotlb_unmap_sg_attrs);
@@ -850,11 +884,11 @@
BUG_ON(dir == DMA_NONE);
for_each_sg(sgl, sg, nelems, i) {
- if (sg->dma_address != swiotlb_sg_to_bus(hwdev, sg))
+ if (sg->dma_address != swiotlb_virt_to_bus(hwdev, sg_virt(sg)))
sync_single(hwdev, swiotlb_bus_to_virt(sg->dma_address),
sg->dma_length, dir, target);
else if (dir == DMA_FROM_DEVICE)
- dma_mark_clean(swiotlb_bus_to_virt(sg->dma_address), sg->dma_length);
+ dma_mark_clean(sg_virt(sg), sg->dma_length);
}
}