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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>
* Copyright (C) 2000, 2003 Hewlett-Packard Co
* David Mosberger-Tang <davidm@hpl.hp.com>
*
* 03/05/07 davidm Switch from PCI-DMA to generic device DMA API.
* 00/12/13 davidm Rename to swiotlb.c and add mark_clean() to avoid
* unnecessary i-cache flushing.
* 04/07/.. ak Better overflow handling. Assorted fixes.
*/
#include <linux/cache.h>
#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 <linux/ctype.h>
#include <asm/io.h>
#include <asm/pci.h>
#include <asm/dma.h>
#include <linux/init.h>
#include <linux/bootmem.h>
#define OFFSET(val,align) ((unsigned long) \
( (val) & ( (align) - 1)))
#define SG_ENT_VIRT_ADDRESS(sg) (page_address((sg)->page) + (sg)->offset)
#define SG_ENT_PHYS_ADDRESS(SG) virt_to_phys(SG_ENT_VIRT_ADDRESS(SG))
/*
* Maximum allowable number of contiguous slabs to map,
* must be a power of 2. What is the appropriate value ?
* The complexity of {map,unmap}_single is linearly dependent on this value.
*/
#define IO_TLB_SEGSIZE 128
/*
* log of the size of each IO TLB slab. The number of slabs is command line
* controllable.
*/
#define IO_TLB_SHIFT 11
int swiotlb_force;
/*
* 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;
/*
* When the IOMMU overflows we return a fallback buffer. This sets the size.
*/
static unsigned long io_tlb_overflow = 32*1024;
void *io_tlb_overflow_buffer;
/*
* 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 DEFINE_SPINLOCK(io_tlb_lock);
static int __init
setup_io_tlb_npages(char *str)
{
if (isdigit(*str)) {
io_tlb_nslabs = simple_strtoul(str, &str, 0) <<
(PAGE_SHIFT - IO_TLB_SHIFT);
/* avoid tail segment of size < IO_TLB_SEGSIZE */
io_tlb_nslabs = ALIGN(io_tlb_nslabs, IO_TLB_SEGSIZE);
}
if (*str == ',')
++str;
if (!strcmp(str, "force"))
swiotlb_force = 1;
return 1;
}
__setup("swiotlb=", setup_io_tlb_npages);
/* make io_tlb_overflow tunable too? */
/*
* 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_with_default_size (size_t default_size)
{
unsigned long i;
if (!io_tlb_nslabs) {
io_tlb_nslabs = (default_size >> PAGE_SHIFT);
io_tlb_nslabs = ALIGN(io_tlb_nslabs, IO_TLB_SEGSIZE);
}
/*
* 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)
panic("Cannot allocate SWIOTLB buffer");
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 up to IO_TLB_SEGSIZE
* 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_SEGSIZE - OFFSET(i, IO_TLB_SEGSIZE);
io_tlb_index = 0;
io_tlb_orig_addr = alloc_bootmem(io_tlb_nslabs * sizeof(char *));
/*
* Get the overflow emergency buffer
*/
io_tlb_overflow_buffer = alloc_bootmem_low(io_tlb_overflow);
printk(KERN_INFO "Placing software IO TLB between 0x%lx - 0x%lx\n",
virt_to_phys(io_tlb_start), virt_to_phys(io_tlb_end));
}
void
swiotlb_init (void)
{
swiotlb_init_with_default_size(64 * (1<<20)); /* default to 64MB */
}
static inline int
address_needs_mapping(struct device *hwdev, dma_addr_t addr)
{
dma_addr_t mask = 0xffffffff;
/* If the device has a mask, use it, otherwise default to 32 bits */
if (hwdev && hwdev->dma_mask)
mask = *hwdev->dma_mask;
return (addr & ~mask) != 0;
}
/*
* Allocates bounce buffer and returns its kernel virtual address.
*/
static void *
map_single(struct device *hwdev, char *buffer, size_t size, int dir)
{
unsigned long flags;
char *dma_addr;
unsigned int nslots, stride, index, wrap;
int i;
/*
* For mappings greater than a page, we limit the stride (and
* hence alignment) to a page size.
*/
nslots = ALIGN(size, 1 << IO_TLB_SHIFT) >> IO_TLB_SHIFT;
if (size > PAGE_SIZE)
stride = (1 << (PAGE_SHIFT - IO_TLB_SHIFT));
else
stride = 1;
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 < (int) (index + nslots); i++)
io_tlb_list[i] = 0;
for (i = index - 1; (OFFSET(i, IO_TLB_SEGSIZE) != IO_TLB_SEGSIZE -1) && 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);
spin_unlock_irqrestore(&io_tlb_lock, flags);
return NULL;
}
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 (dir == DMA_TO_DEVICE || dir == 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 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) >>
|