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swiotlb: support bouncing of HighMem pages 

Impact: prepare the swiotlb code for HighMem struct pages

This requires us to treat DMA regions in terms of page+offset rather
than virtual addressing since a HighMem page may not have a mapping.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Jeremy Fitzhardinge 2008-12-16 12:17:33 -08:00 committed by Ingo Molnar
parent 1b548f667c
commit ef9b189352
1 changed files with 89 additions and 33 deletions
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122
lib/swiotlb.c
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@ -26,6 +26,7 @@
#include <linux/swiotlb.h>
#include <linux/types.h>
#include <linux/ctype.h>
#include <linux/highmem.h>
#include <asm/io.h>
#include <asm/dma.h>
@ -38,9 +39,6 @@
#define OFFSET(val,align) ((unsigned long) \
( (val) & ( (align) - 1)))
#define SG_ENT_VIRT_ADDRESS(sg) (sg_virt((sg)))
#define SG_ENT_PHYS_ADDRESS(sg) virt_to_bus(SG_ENT_VIRT_ADDRESS(sg))
#define SLABS_PER_PAGE (1 << (PAGE_SHIFT - IO_TLB_SHIFT))
/*
@ -91,7 +89,10 @@ static unsigned int io_tlb_index;
* We need to save away the original address corresponding to a mapped entry
* for the sync operations.
*/
static unsigned char **io_tlb_orig_addr;
static struct swiotlb_phys_addr {
struct page *page;
unsigned int offset;
} *io_tlb_orig_addr;
/*
* Protect the above data structures in the map and unmap calls
@ -150,6 +151,11 @@ int __weak swiotlb_arch_range_needs_mapping(void *ptr, size_t size)
return 0;
}
static dma_addr_t swiotlb_sg_to_bus(struct scatterlist *sg)
{
return swiotlb_phys_to_bus(page_to_phys(sg_page(sg)) + sg->offset);
}
/*
* Statically reserve bounce buffer space and initialize bounce buffer data
* structures for the software IO TLB used to implement the DMA API.
@ -183,7 +189,7 @@ swiotlb_init_with_default_size(size_t default_size)
for (i = 0; i < io_tlb_nslabs; i++)
io_tlb_list[i] = IO_TLB_SEGSIZE - OFFSET(i, IO_TLB_SEGSIZE);
io_tlb_index = 0;
io_tlb_orig_addr = alloc_bootmem(io_tlb_nslabs * sizeof(char *));
io_tlb_orig_addr = alloc_bootmem(io_tlb_nslabs * sizeof(struct swiotlb_phys_addr));
/*
* Get the overflow emergency buffer
@ -258,12 +264,12 @@ swiotlb_late_init_with_default_size(size_t default_size)
io_tlb_list[i] = IO_TLB_SEGSIZE - OFFSET(i, IO_TLB_SEGSIZE);
io_tlb_index = 0;
io_tlb_orig_addr = (unsigned char **)__get_free_pages(GFP_KERNEL,
get_order(io_tlb_nslabs * sizeof(char *)));
io_tlb_orig_addr = (struct swiotlb_phys_addr *)__get_free_pages(GFP_KERNEL,
get_order(io_tlb_nslabs * sizeof(struct swiotlb_phys_addr)));
if (!io_tlb_orig_addr)
goto cleanup3;
memset(io_tlb_orig_addr, 0, io_tlb_nslabs * sizeof(char *));
memset(io_tlb_orig_addr, 0, io_tlb_nslabs * sizeof(struct swiotlb_phys_addr));
/*
* Get the overflow emergency buffer
@ -312,20 +318,59 @@ static int is_swiotlb_buffer(char *addr)
return addr >= io_tlb_start && addr < io_tlb_end;
}
static void
__sync_single(char *buffer, char *dma_addr, size_t size, int dir)
static struct swiotlb_phys_addr swiotlb_bus_to_phys_addr(char *dma_addr)
{
if (dir == DMA_TO_DEVICE)
memcpy(dma_addr, buffer, size);
else
memcpy(buffer, dma_addr, size);
int index = (dma_addr - io_tlb_start) >> IO_TLB_SHIFT;
struct swiotlb_phys_addr buffer = io_tlb_orig_addr[index];
buffer.offset += (long)dma_addr & ((1 << IO_TLB_SHIFT) - 1);
buffer.page += buffer.offset >> PAGE_SHIFT;
buffer.offset &= PAGE_SIZE - 1;
return buffer;
}
static void
__sync_single(struct swiotlb_phys_addr buffer, char *dma_addr, size_t size, int dir)
{
if (PageHighMem(buffer.page)) {
size_t len, bytes;
char *dev, *host, *kmp;
len = size;
while (len != 0) {
unsigned long flags;
bytes = len;
if ((bytes + buffer.offset) > PAGE_SIZE)
bytes = PAGE_SIZE - buffer.offset;
local_irq_save(flags); /* protects KM_BOUNCE_READ */
kmp = kmap_atomic(buffer.page, KM_BOUNCE_READ);
dev = dma_addr + size - len;
host = kmp + buffer.offset;
if (dir == DMA_FROM_DEVICE)
memcpy(host, dev, bytes);
else
memcpy(dev, host, bytes);
kunmap_atomic(kmp, KM_BOUNCE_READ);
local_irq_restore(flags);
len -= bytes;
buffer.page++;
buffer.offset = 0;
}
} else {
void *v = page_address(buffer.page) + buffer.offset;
if (dir == DMA_TO_DEVICE)
memcpy(dma_addr, v, size);
else
memcpy(v, dma_addr, size);
}
}
/*
* Allocates bounce buffer and returns its kernel virtual address.
*/
static void *
map_single(struct device *hwdev, char *buffer, size_t size, int dir)
map_single(struct device *hwdev, struct swiotlb_phys_addr buffer, size_t size, int dir)
{
unsigned long flags;
char *dma_addr;
@ -335,6 +380,7 @@ map_single(struct device *hwdev, char *buffer, size_t size, int dir)
unsigned long mask;
unsigned long offset_slots;
unsigned long max_slots;
struct swiotlb_phys_addr slot_buf;
mask = dma_get_seg_boundary(hwdev);
start_dma_addr = swiotlb_virt_to_bus(io_tlb_start) & mask;
@ -419,8 +465,13 @@ found:
* This is needed when we sync the memory. Then we sync the buffer if
* needed.
*/
for (i = 0; i < nslots; i++)
io_tlb_orig_addr[index+i] = buffer + (i << IO_TLB_SHIFT);
slot_buf = buffer;
for (i = 0; i < nslots; i++) {
slot_buf.page += slot_buf.offset >> PAGE_SHIFT;
slot_buf.offset &= PAGE_SIZE - 1;
io_tlb_orig_addr[index+i] = slot_buf;
slot_buf.offset += 1 << IO_TLB_SHIFT;
}
if (dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL)
__sync_single(buffer, dma_addr, size, DMA_TO_DEVICE);
@ -436,12 +487,12 @@ unmap_single(struct device *hwdev, char *dma_addr, size_t size, int dir)
unsigned long flags;
int i, count, nslots = ALIGN(size, 1 << IO_TLB_SHIFT) >> IO_TLB_SHIFT;
int index = (dma_addr - io_tlb_start) >> IO_TLB_SHIFT;
char *buffer = io_tlb_orig_addr[index];
struct swiotlb_phys_addr buffer = swiotlb_bus_to_phys_addr(dma_addr);
/*
* First, sync the memory before unmapping the entry
*/
if (buffer && ((dir == DMA_FROM_DEVICE) || (dir == DMA_BIDIRECTIONAL)))
if ((dir == DMA_FROM_DEVICE) || (dir == DMA_BIDIRECTIONAL))
/*
* bounce... copy the data back into the original buffer * and
* delete the bounce buffer.
@ -478,10 +529,7 @@ static void
sync_single(struct device *hwdev, char *dma_addr, size_t size,
int dir, int target)
{
int index = (dma_addr - io_tlb_start) >> IO_TLB_SHIFT;
char *buffer = io_tlb_orig_addr[index];
buffer += ((unsigned long)dma_addr & ((1 << IO_TLB_SHIFT) - 1));
struct swiotlb_phys_addr buffer = swiotlb_bus_to_phys_addr(dma_addr);
switch (target) {
case SYNC_FOR_CPU:
@ -529,7 +577,10 @@ swiotlb_alloc_coherent(struct device *hwdev, size_t size,
* swiotlb_map_single(), which will grab memory from
* the lowest available address range.
*/
ret = map_single(hwdev, NULL, size, DMA_FROM_DEVICE);
struct swiotlb_phys_addr buffer;
buffer.page = virt_to_page(NULL);
buffer.offset = 0;
ret = map_single(hwdev, buffer, size, DMA_FROM_DEVICE);
if (!ret)
return NULL;
}
@ -597,6 +648,7 @@ swiotlb_map_single_attrs(struct device *hwdev, void *ptr, size_t size,
{
dma_addr_t dev_addr = swiotlb_virt_to_bus(ptr);
void *map;
struct swiotlb_phys_addr buffer;
BUG_ON(dir == DMA_NONE);
/*
@ -611,7 +663,9 @@ swiotlb_map_single_attrs(struct device *hwdev, void *ptr, size_t size,
/*
* Oh well, have to allocate and map a bounce buffer.
*/
map = map_single(hwdev, ptr, size, dir);
buffer.page = virt_to_page(ptr);
buffer.offset = (unsigned long)ptr & ~PAGE_MASK;
map = map_single(hwdev, buffer, size, dir);
if (!map) {
swiotlb_full(hwdev, size, dir, 1);
map = io_tlb_overflow_buffer;
@ -756,18 +810,20 @@ swiotlb_map_sg_attrs(struct device *hwdev, struct scatterlist *sgl, int nelems,
int dir, struct dma_attrs *attrs)
{
struct scatterlist *sg;
void *addr;
struct swiotlb_phys_addr buffer;
dma_addr_t dev_addr;
int i;
BUG_ON(dir == DMA_NONE);
for_each_sg(sgl, sg, nelems, i) {
addr = SG_ENT_VIRT_ADDRESS(sg);
dev_addr = swiotlb_virt_to_bus(addr);
dev_addr = swiotlb_sg_to_bus(sg);
if (range_needs_mapping(sg_virt(sg), sg->length) ||
address_needs_mapping(hwdev, dev_addr, sg->length)) {
void *map = map_single(hwdev, addr, sg->length, dir);
void *map;
buffer.page = sg_page(sg);
buffer.offset = sg->offset;
map = map_single(hwdev, buffer, sg->length, dir);
if (!map) {
/* Don't panic here, we expect map_sg users
to do proper error handling. */
@ -807,11 +863,11 @@ 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 != SG_ENT_PHYS_ADDRESS(sg))
if (sg->dma_address != swiotlb_sg_to_bus(sg))
unmap_single(hwdev, swiotlb_bus_to_virt(sg->dma_address),
sg->dma_length, dir);
else if (dir == DMA_FROM_DEVICE)
dma_mark_clean(SG_ENT_VIRT_ADDRESS(sg), sg->dma_length);
dma_mark_clean(swiotlb_bus_to_virt(sg->dma_address), sg->dma_length);
}
}
EXPORT_SYMBOL(swiotlb_unmap_sg_attrs);
@ -840,11 +896,11 @@ 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 != SG_ENT_PHYS_ADDRESS(sg))
if (sg->dma_address != swiotlb_sg_to_bus(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(SG_ENT_VIRT_ADDRESS(sg), sg->dma_length);
dma_mark_clean(swiotlb_bus_to_virt(sg->dma_address), sg->dma_length);
}
}