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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>
This commit is contained in:
Becky Bruce 2008-12-22 10:26:09 -08:00 committed by Ingo Molnar
parent bc40ac6698
commit fb05a37929
1 changed files with 51 additions and 17 deletions
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68
lib/swiotlb.c
View File

@ -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 @@ int __weak swiotlb_arch_range_needs_mapping(void *ptr, size_t size)
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;
@ -329,6 +326,47 @@ static int is_swiotlb_buffer(char *addr)
return addr >= io_tlb_start && addr < io_tlb_end;
}
/*
* 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.
*/
@ -430,7 +468,7 @@ found:
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 @@ unmap_single(struct device *hwdev, char *dma_addr, size_t size, int dir)
* 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 @@ sync_single(struct device *hwdev, char *dma_addr, size_t size,
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 @@ swiotlb_unmap_sg_attrs(struct device *hwdev, struct scatterlist *sgl,
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 @@ swiotlb_sync_sg(struct device *hwdev, struct scatterlist *sgl,
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);
}
}