Viewing file:  swiotlb.c (13.37 KB) -rw-r--r--
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/*
* Dynamic DMA mapping support.
*
* This implementation is for IA-64 platforms that do not support
* I/O TLBs (aka DMA address translation hardware).
* Copyright (C) 2000 Asit Mallick <Asit.K.Mallick@intel.com>
* Copyright (C) 2000 Goutham Rao <goutham.rao@intel.com>
*
* 00/12/13 davidm Rename to swiotlb.c and add mark_clean() to avoid
* unnecessary i-cache flushing.
*/
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/pci.h>
#include <linux/spinlock.h>
#include <linux/string.h>
#include <linux/types.h>
#include <asm/io.h>
#include <asm/pci.h>
#include <asm/dma.h>
#include <linux/init.h>
#include <linux/bootmem.h>
#define ALIGN(val, align) ((unsigned long) \
(((unsigned long) (val) + ((align) - 1)) & ~((align) - 1)))
#define SG_ENT_VIRT_ADDRESS(sg) ((sg)->address ? (sg)->address \
: page_address((sg)->page) + (sg)->offset)
#define SG_ENT_PHYS_ADDRESS(SG) virt_to_phys(SG_ENT_VIRT_ADDRESS(SG))
/*
* log of the size of each IO TLB slab. The number of slabs is command line controllable.
*/
#define IO_TLB_SHIFT 11
/*
* Used to do a quick range check in swiotlb_unmap_single and swiotlb_sync_single, to see
* if the memory was in fact allocated by this API.
*/
static char *io_tlb_start, *io_tlb_end;
/*
* The number of IO TLB blocks (in groups of 64) betweeen io_tlb_start and io_tlb_end.
* This is command line adjustable via setup_io_tlb_npages.
*/
static unsigned long io_tlb_nslabs = 1024;
/*
* This is a free list describing the number of free entries available from each index
*/
static unsigned int *io_tlb_list;
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;
/*
* Protect the above data structures in the map and unmap calls
*/
static spinlock_t io_tlb_lock = SPIN_LOCK_UNLOCKED;
static int __init
setup_io_tlb_npages (char *str)
{
io_tlb_nslabs = simple_strtoul(str, NULL, 0) << (PAGE_SHIFT - IO_TLB_SHIFT);
return 1;
}
__setup("swiotlb=", setup_io_tlb_npages);
/*
* Statically reserve bounce buffer space and initialize bounce buffer data structures for
* the software IO TLB used to implement the PCI DMA API.
*/
void
swiotlb_init (void)
{
int i;
/*
* Get IO TLB memory from the low pages
*/
io_tlb_start = alloc_bootmem_low_pages(io_tlb_nslabs * (1 << IO_TLB_SHIFT));
if (!io_tlb_start)
BUG();
io_tlb_end = io_tlb_start + io_tlb_nslabs * (1 << IO_TLB_SHIFT);
/*
* Allocate and initialize the free list array. This array is used
* to find contiguous free memory regions of size 2^IO_TLB_SHIFT between
* io_tlb_start and io_tlb_end.
*/
io_tlb_list = alloc_bootmem(io_tlb_nslabs * sizeof(int));
for (i = 0; i < io_tlb_nslabs; i++)
io_tlb_list[i] = io_tlb_nslabs - i;
io_tlb_index = 0;
io_tlb_orig_addr = alloc_bootmem(io_tlb_nslabs * sizeof(char *));
printk("Placing software IO TLB between 0x%p - 0x%p\n",
(void *) io_tlb_start, (void *) io_tlb_end);
}
/*
* Allocates bounce buffer and returns its kernel virtual address.
*/
static void *
map_single (struct pci_dev *hwdev, char *buffer, size_t size, int direction)
{
unsigned long flags;
char *dma_addr;
unsigned int nslots, stride, index, wrap;
int i;
/*
* For mappings greater than a page size, we limit the stride (and hence alignment)
* to a page size.
*/
nslots = ALIGN(size, 1 << IO_TLB_SHIFT) >> IO_TLB_SHIFT;
if (size > (1 << PAGE_SHIFT))
stride = (1 << (PAGE_SHIFT - IO_TLB_SHIFT));
else
stride = nslots;
if (!nslots)
BUG();
/*
* Find suitable number of IO TLB entries size that will fit this request and
* allocate a buffer from that IO TLB pool.
*/
spin_lock_irqsave(&io_tlb_lock, flags);
{
wrap = index = ALIGN(io_tlb_index, stride);
if (index >= io_tlb_nslabs)
wrap = index = 0;
do {
/*
* If we find a slot that indicates we have 'nslots' number of
* contiguous buffers, we allocate the buffers from that slot and
* mark the entries as '0' indicating unavailable.
*/
if (io_tlb_list[index] >= nslots) {
int count = 0;
for (i = index; i < index + nslots; i++)
io_tlb_list[i] = 0;
for (i = index - 1; (i >= 0) && io_tlb_list[i]; i--)
io_tlb_list[i] = ++count;
dma_addr = io_tlb_start + (index << IO_TLB_SHIFT);
/*
* Update the indices to avoid searching in the next round.
*/
io_tlb_index = ((index + nslots) < io_tlb_nslabs
? (index + nslots) : 0);
goto found;
}
index += stride;
if (index >= io_tlb_nslabs)
index = 0;
} while (index != wrap);
/*
* XXX What is a suitable recovery mechanism here? We cannot
* sleep because we are called from with in interrupts!
*/
panic("map_single: could not allocate software IO TLB (%ld bytes)", size);
}
found:
spin_unlock_irqrestore(&io_tlb_lock, flags);
/*
* Save away the mapping from the original address to the DMA address. This is
* needed when we sync the memory. Then we sync the buffer if needed.
*/
io_tlb_orig_addr[index] = buffer;
if (direction == PCI_DMA_TODEVICE || direction == PCI_DMA_BIDIRECTIONAL)
memcpy(dma_addr, buffer, size);
return dma_addr;
}
/*
* dma_addr is the kernel virtual address of the bounce buffer to unmap.
*/
static void
unmap_single (struct pci_dev *hwdev, char *dma_addr, size_t size, int direction)
{
unsigned long flags;
int i, 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];
/*
* First, sync the memory before unmapping the entry
*/
if ((direction == PCI_DMA_FROMDEVICE) || (direction == PCI_DMA_BIDIRECTIONAL))
/*
* bounce... copy the data back into the original buffer * and delete the
* bounce buffer.
*/
memcpy(buffer, dma_addr, size);
/*
* Return the buffer to the free list by setting the corresponding entries to
* indicate the number of contigous entries available. While returning the
* entries to the free list, we merge the entries with slots below and above the
* pool being returned.
*/
spin_lock_irqsave(&io_tlb_lock, flags);
{
int count = ((index + nslots) < io_tlb_nslabs ? io_tlb_list[index + nslots] : 0);
/*
* Step 1: return the slots to the free list, merging the slots with
* superceeding slots
*/
for (i = index + nslots - 1; i >= index; i--)
io_tlb_list[i] = ++count;
/*
* Step 2: merge the returned slots with the preceeding slots, if
* available (non zero)
*/
for (i = index - 1; (i >= 0) && io_tlb_list[i]; i--)
io_tlb_list[i] = ++count;
}
spin_unlock_irqrestore(&io_tlb_lock, flags);
}
static void
sync_single (struct pci_dev *hwdev, char *dma_addr, size_t size, int direction)
{
int index = (dma_addr - io_tlb_start) >> IO_TLB_SHIFT;
char *buffer = io_tlb_orig_addr[index];
/*
* bounce... copy the data back into/from the original buffer
* XXX How do you handle PCI_DMA_BIDIRECTIONAL here ?
*/
if (direction == PCI_DMA_FROMDEVICE)
memcpy(buffer, dma_addr, size);
else if (direction == PCI_DMA_TODEVICE)
memcpy(dma_addr, buffer, size);
else
BUG();
}
void *
swiotlb_alloc_consistent (struct pci_dev *hwdev, size_t size, dma_addr_t *dma_handle)
{
unsigned long pci_addr;
int gfp = GFP_ATOMIC;
void *ret;
if (!hwdev || hwdev->dma_mask <= 0xffffffff)
gfp |= GFP_DMA; /* XXX fix me: should change this to GFP_32BIT or ZONE_32BIT */
ret = (void *)__get_free_pages(gfp, get_order(size));
if (!ret)
return NULL;
memset(ret, 0, size);
pci_addr = virt_to_phys(ret);
if (hwdev && (pci_addr & ~hwdev->dma_mask) != 0)
panic("swiotlb_alloc_consistent: allocated memory is out of range for PCI device");
*dma_handle = pci_addr;
return ret;
}
void
swiotlb_free_consistent (struct pci_dev *hwdev, size_t size, void *vaddr, dma_addr_t dma_handle)
{
free_pages((unsigned long) vaddr, get_order(size));
}
/*
* Map a single buffer of the indicated size for DMA in streaming mode. The PCI address
* to use is returned.
*
* Once the device is given the dma address, the device owns this memory until either
* swiotlb_unmap_single or swiotlb_dma_sync_single is performed.
*/
dma_addr_t
swiotlb_map_single (struct pci_dev *hwdev, void *ptr, size_t size, int direction)
{
unsigned long pci_addr = virt_to_phys(ptr);
if (direction == PCI_DMA_NONE)
BUG();
/*
* Check if the PCI device can DMA to ptr... if so, just return ptr
*/
if ((pci_addr & ~hwdev->dma_mask) == 0)
/*
* Device is bit capable of DMA'ing to the buffer... just return the PCI
* address of ptr
*/
return pci_addr;
/*
* get a bounce buffer:
*/
pci_addr = virt_to_phys(map_single(hwdev, ptr, size, direction));
/*
* Ensure that the address returned is DMA'ble:
*/
if ((pci_addr & ~hwdev->dma_mask) != 0)
panic("map_single: bounce buffer is not DMA'ble");
return pci_addr;
}
/*
* Since DMA is i-cache coherent, any (complete) pages that were written via
* DMA can be marked as "clean" so that update_mmu_cache() doesn't have to
* flush them when they get mapped into an executable vm-area.
*/
static void
mark_clean (void *addr, size_t size)
{
unsigned long pg_addr, end;
pg_addr = PAGE_ALIGN((unsigned long) addr);
end = (unsigned long) addr + size;
while (pg_addr + PAGE_SIZE <= end) {
struct page *page = virt_to_page(pg_addr);
set_bit(PG_arch_1, &page->flags);
pg_addr += PAGE_SIZE;
}
}
/*
* Unmap a single streaming mode DMA translation. The dma_addr and size must match what
* was provided for in a previous swiotlb_map_single call. All other usages are
* undefined.
*
* After this call, reads by the cpu to the buffer are guarenteed to see whatever the
* device wrote there.
*/
void
swiotlb_unmap_single (struct pci_dev *hwdev, dma_addr_t pci_addr, size_t size, int direction)
{
char *dma_addr = phys_to_virt(pci_addr);
if (direction == PCI_DMA_NONE)
BUG();
if (dma_addr >= io_tlb_start && dma_addr < io_tlb_end)
unmap_single(hwdev, dma_addr, size, direction);
else if (direction == PCI_DMA_FROMDEVICE)
mark_clean(dma_addr, size);
}
/*
* Make physical memory consistent for a single streaming mode DMA translation after a
* transfer.
*
* If you perform a swiotlb_map_single() but wish to interrogate the buffer using the cpu,
* yet do not wish to teardown the PCI dma mapping, you must call this function before
* doing so. At the next point you give the PCI dma address back to the card, the device
* again owns the buffer.
*/
void
swiotlb_sync_single (struct pci_dev *hwdev, dma_addr_t pci_addr, size_t size, int direction)
{
char *dma_addr = phys_to_virt(pci_addr);
if (direction == PCI_DMA_NONE)
BUG();
if (dma_addr >= io_tlb_start && dma_addr < io_tlb_end)
sync_single(hwdev, dma_addr, size, direction);
else if (direction == PCI_DMA_FROMDEVICE)
mark_clean(dma_addr, size);
}
/*
* Map a set of buffers described by scatterlist in streaming mode for DMA. This is the
* scather-gather version of the above swiotlb_map_single interface. Here the scatter
* gather list elements are each tagged with the appropriate dma address and length. They
* are obtained via sg_dma_{address,length}(SG).
*
* NOTE: An implementation may be able to use a smaller number of
* DMA address/length pairs than there are SG table elements.
* (for example via virtual mapping capabilities)
* The routine returns the number of addr/length pairs actually
* used, at most nents.
*
* Device ownership issues as mentioned above for swiotlb_map_single are the same here.
*/
int
swiotlb_map_sg (struct pci_dev *hwdev, struct scatterlist *sg, int nelems, int direction)
{
void *addr;
int i;
if (direction == PCI_DMA_NONE)
BUG();
for (i = 0; i < nelems; i++, sg++) {
sg->orig_address = SG_ENT_VIRT_ADDRESS(sg);
if ((SG_ENT_PHYS_ADDRESS(sg) & ~hwdev->dma_mask) != 0) {
addr = map_single(hwdev, sg->address, sg->length, direction);
if (sg->address)
sg->address = addr;
else
sg->page = virt_to_page(addr);
}
}
return nelems;
}
/*
* Unmap a set of streaming mode DMA translations. Again, cpu read rules concerning calls
* here are the same as for swiotlb_unmap_single() above.
*/
void
swiotlb_unmap_sg (struct pci_dev *hwdev, struct scatterlist *sg, int nelems, int direction)
{
int i;
if (direction == PCI_DMA_NONE)
BUG();
for (i = 0; i < nelems; i++, sg++)
if (sg->orig_address != SG_ENT_VIRT_ADDRESS(sg)) {
unmap_single(hwdev, SG_ENT_VIRT_ADDRESS(sg), sg->length, direction);
if (sg->address)
sg->address = sg->orig_address;
else
sg->page = virt_to_page(sg->orig_address);
} else if (direction == PCI_DMA_FROMDEVICE)
mark_clean(sg->address, sg->length);
}
/*
* Make physical memory consistent for a set of streaming mode DMA translations after a
* transfer.
*
* The same as swiotlb_dma_sync_single but for a scatter-gather list, same rules and
* usage.
*/
void
swiotlb_sync_sg (struct pci_dev *hwdev, struct scatterlist *sg, int nelems, int direction)
{
int i;
if (direction == PCI_DMA_NONE)
BUG();
for (i = 0; i < nelems; i++, sg++)
if (sg->orig_address != SG_ENT_VIRT_ADDRESS(sg))
sync_single(hwdev, SG_ENT_VIRT_ADDRESS(sg), sg->length, direction);
}
unsigned long
swiotlb_dma_address (struct scatterlist *sg)
{
return SG_ENT_PHYS_ADDRESS(sg);
}
EXPORT_SYMBOL(swiotlb_init);
EXPORT_SYMBOL(swiotlb_map_single);
EXPORT_SYMBOL(swiotlb_unmap_single);
EXPORT_SYMBOL(swiotlb_map_sg);
EXPORT_SYMBOL(swiotlb_unmap_sg);
EXPORT_SYMBOL(swiotlb_sync_single);
EXPORT_SYMBOL(swiotlb_sync_sg);
EXPORT_SYMBOL(swiotlb_dma_address);
EXPORT_SYMBOL(swiotlb_alloc_consistent);
EXPORT_SYMBOL(swiotlb_free_consistent);
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