/*
* 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);
/* 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 >> IO_TLB_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_limit(io_tlb_nslabs *
(1 << IO_TLB_SHIFT), 0x100000000);
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) >> IO_TLB_SHIFT;
char *buffer = io_tlb_orig_addr[index];
/*
* First, sync the memory before unmapping the entry
*/
if (buffer && ((dir == DMA_FROM_DEVICE) || (dir == 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);
{
count = ((index + nslots) < ALIGN(index + 1, IO_TLB_SEGSIZE) ?
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 preceding slots,
* if available (non zero)
*/
for (i = index - 1; (OFFSET(i, IO_TLB_SEGSIZE) != IO_TLB_SEGSIZE -1) && io_tlb_list[i]; i--)
io_tlb_list[i] = ++count;
}
spin_unlock_irqrestore(&io_tlb_lock, flags);
}
static void
sync_single(struct device *hwdev, char *dma_addr, size_t size, int dir)
{
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 DMA_BIDIRECTIONAL here ?
*/
if (dir == DMA_FROM_DEVICE)
memcpy(buffer, dma_addr, size);
else if (dir == DMA_TO_DEVICE)
memcpy(dma_addr, buffer, size);
else
BUG();
}
void *
swiotlb_alloc_coherent(struct device *hwdev, size_t size,
dma_addr_t *dma_handle, int flags)
{
unsigned long dev_addr;
void *ret;
int order = get_order(size);
/*
* XXX fix me: the DMA API should pass us an explicit DMA mask
* instead, or use ZONE_DMA32 (ia64 overloads ZONE_DMA to be a ~32
* bit range instead of a 16MB one).
*/
flags |= GFP_DMA;
ret = (void *)__get_free_pages(flags, order);
if (ret && address_needs_mapping(hwdev, virt_to_phys(ret))) {
/*
* The allocated memory isn't reachable by the device.
* Fall back on swiotlb_map_single().
*/
free_pages((unsigned long) ret, order);
ret = NULL;
}
if (!ret) {
/*
* We are either out of memory or the device can't DMA
* to GFP_DMA memory; fall back on
* swiotlb_map_single(), which will grab memory from
* the lowest available address range.
*/
dma_addr_t handle;
handle = swiotlb_map_single(NULL, NULL, size, DMA_FROM_DEVICE);
if (dma_mapping_error(handle))
return NULL;
ret = phys_to_virt(handle);
}
memset(ret, 0, size);
dev_addr = virt_to_phys(ret);
/* Confirm address can be DMA'd by device */
if (address_needs_mapping(hwdev, dev_addr)) {
printk("hwdev DMA mask = 0x%016Lx, dev_addr = 0x%016lx\n",
(unsigned long long)*hwdev->dma_mask, dev_addr);
panic("swiotlb_alloc_coherent: allocated memory is out of "
"range for device");
}
*dma_handle = dev_addr;
return ret;
}
void
swiotlb_free_coherent(struct device *hwdev, size_t size, void *vaddr,
dma_addr_t dma_handle)
{
if (!(vaddr >= (void *)io_tlb_start
&& vaddr < (void *)io_tlb_end))
free_pages((unsigned long) vaddr, get_order(size));
else
/* DMA_TO_DEVICE to avoid memcpy in unmap_single */
swiotlb_unmap_single (hwdev, dma_handle, size, DMA_TO_DEVICE);
}
static void
swiotlb_full(struct device *dev, size_t size, int dir, int do_panic)
{
/*
* Ran out of IOMMU space for this operation. This is very bad.
* Unfortunately the drivers cannot handle this operation properly.
* unless they check for pci_dma_mapping_error (most don't)
* When the mapping is small enough return a static buffer to limit
* the damage, or panic when the transfer is too big.
*/
printk(KERN_ERR "PCI-DMA: Out of SW-IOMMU space for %lu bytes at "
"device %s\n", size, dev ? dev->bus_id : "?");
if (size > io_tlb_overflow && do_panic) {
if (dir == PCI_DMA_FROMDEVICE || dir == PCI_DMA_BIDIRECTIONAL)
panic("PCI-DMA: Memory would be corrupted\n");
if (dir == PCI_DMA_TODEVICE || dir == PCI_DMA_BIDIRECTIONAL)
panic("PCI-DMA: Random memory would be DMAed\n");
}
}
/*
* 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 device *hwdev, void *ptr, size_t size, int dir)
{
unsigned long dev_addr = virt_to_phys(ptr);
void *map;
if (dir == DMA_NONE)
BUG();
/*
* If the pointer passed in happens to be in the device's DMA window,
* we can safely return the device addr and not worry about bounce
* buffering it.
*/
if (!address_needs_mapping(hwdev, dev_addr) && !swiotlb_force)
return dev_addr;
/*
* Oh well, have to allocate and map a bounce buffer.
*/
map = map_single(hwdev, ptr, size, dir);
if (!map) {
swiotlb_full(hwdev, size, dir, 1);
map = io_tlb_overflow_buffer;
}
dev_addr = virt_to_phys(map);
/*
* Ensure that the address returned is DMA'ble
*/
if (address_needs_mapping(hwdev, dev_addr))
panic("map_single: bounce buffer is not DMA'ble");
return dev_addr;
}
/*
* Since DMA is i-cache coherent, any (complete) pages that were written via
* DMA can be marked as "clean" so that lazy_mmu_prot_update() 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 guaranteed to see
* whatever the device wrote there.
*/
void
swiotlb_unmap_single(struct device *hwdev, dma_addr_t dev_addr, size_t size,
int dir)
{
char *dma_addr = phys_to_virt(dev_addr);
if (dir == DMA_NONE)
BUG();
if (dma_addr >= io_tlb_start && dma_addr < io_tlb_end)
unmap_single(hwdev, dma_addr, size, dir);
else if (dir == DMA_FROM_DEVICE)
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, you must first perform a
* swiotlb_dma_sync_for_device, and then the device again owns the buffer
*/
void
swiotlb_sync_single_for_cpu(struct device *hwdev, dma_addr_t dev_addr,
size_t size, int dir)
{
char *dma_addr = phys_to_virt(dev_addr);
if (dir == DMA_NONE)
BUG();
if (dma_addr >= io_tlb_start && dma_addr < io_tlb_end)
sync_single(hwdev, dma_addr, size, dir);
else if (dir == DMA_FROM_DEVICE)
mark_clean(dma_addr, size);
}
void
swiotlb_sync_single_for_device(struct device *hwdev, dma_addr_t dev_addr,
size_t size, int dir)
{
char *dma_addr = phys_to_virt(dev_addr);
if (dir == DMA_NONE)
BUG();
if (dma_addr >= io_tlb_start && dma_addr < io_tlb_end)
sync_single(hwdev, dma_addr, size, dir);
else if (dir == DMA_FROM_DEVICE)
mark_clean(dma_addr, size);
}
/*
* Map a set of buffers described by scatterlist in streaming mode for DMA.
* This is the scatter-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 device *hwdev, struct scatterlist *sg, int nelems,
int dir)
{
void *addr;
unsigned long dev_addr;
int i;
if (dir == DMA_NONE)
BUG();
for (i = 0; i < nelems; i++, sg++) {
addr = SG_ENT_VIRT_ADDRESS(sg);
dev_addr = virt_to_phys(addr);
if (swiotlb_force || address_needs_mapping(hwdev, dev_addr)) {
sg->dma_address = (dma_addr_t) virt_to_phys(map_single(hwdev, addr, sg->length, dir));
if (!sg->dma_address) {
/* Don't panic here, we expect map_sg users
to do proper error handling. */
swiotlb_full(hwdev, sg->length, dir, 0);
swiotlb_unmap_sg(hwdev, sg - i, i, dir);
sg[0].dma_length = 0;
return 0;
}
} else
sg->dma_address = dev_addr;
sg->dma_length = sg->length;
}
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 device *hwdev, struct scatterlist *sg, int nelems,
int dir)
{
int i;
if (dir == DMA_NONE)
BUG();
for (i = 0; i < nelems; i++, sg++)
if (sg->dma_address != SG_ENT_PHYS_ADDRESS(sg))
unmap_single(hwdev, (void *) phys_to_virt(sg->dma_address), sg->dma_length, dir);
else if (dir == DMA_FROM_DEVICE)
mark_clean(SG_ENT_VIRT_ADDRESS(sg), sg->dma_length);
}
/*
* Make physical memory consistent for a set of streaming mode DMA translations
* after a transfer.
*
* The same as swiotlb_sync_single_* but for a scatter-gather list, same rules
* and usage.
*/
void
swiotlb_sync_sg_for_cpu(struct device *hwdev, struct scatterlist *sg,
int nelems, int dir)
{
int i;
if (dir == DMA_NONE)
BUG();
for (i = 0; i < nelems; i++, sg++)
if (sg->dma_address != SG_ENT_PHYS_ADDRESS(sg))
sync_single(hwdev, (void *) sg->dma_address,
sg->dma_length, dir);
}
void
swiotlb_sync_sg_for_device(struct device *hwdev, struct scatterlist *sg,
int nelems, int dir)
{
int i;
if (dir == DMA_NONE)
BUG();
for (i = 0; i < nelems; i++, sg++)
if (sg->dma_address != SG_ENT_PHYS_ADDRESS(sg))
sync_single(hwdev, (void *) sg->dma_address,
sg->dma_length, dir);
}
int
swiotlb_dma_mapping_error(dma_addr_t dma_addr)
{
return (dma_addr == virt_to_phys(io_tlb_overflow_buffer));
}
/*
* Return whether the given PCI device DMA address mask can be supported
* properly. For example, if your device can only drive the low 24-bits
* during PCI bus mastering, then you would pass 0x00ffffff as the mask to
* this function.
*/
int
swiotlb_dma_supported (struct device *hwdev, u64 mask)
{
return (virt_to_phys (io_tlb_end) - 1) <= mask;
}
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_for_cpu);
EXPORT_SYMBOL(swiotlb_sync_single_for_device);
EXPORT_SYMBOL(swiotlb_sync_sg_for_cpu);
EXPORT_SYMBOL(swiotlb_sync_sg_for_device);
EXPORT_SYMBOL(swiotlb_dma_mapping_error);
EXPORT_SYMBOL(swiotlb_alloc_coherent);
EXPORT_SYMBOL(swiotlb_free_coherent);
EXPORT_SYMBOL(swiotlb_dma_supported);
