linux/arch/powerpc/mm/dma-noncoherent.c
Benjamin Herrenschmidt 8b31e49d1d powerpc: Fix up dma_alloc_coherent() on platforms without cache coherency.
The implementation we just revived has issues, such as using a
Kconfig-defined virtual address area in kernel space that nothing
actually carves out (and thus will overlap whatever is there),
or having some dependencies on being self contained in a single
PTE page which adds unnecessary constraints on the kernel virtual
address space.

This fixes it by using more classic PTE accessors and automatically
locating the area for consistent memory, carving an appropriate hole
in the kernel virtual address space, leaving only the size of that
area as a Kconfig option. It also brings some dma-mask related fixes
from the ARM implementation which was almost identical initially but
grew its own fixes.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2009-05-27 16:33:59 +10:00

400 lines
9.9 KiB
C

/*
* PowerPC version derived from arch/arm/mm/consistent.c
* Copyright (C) 2001 Dan Malek (dmalek@jlc.net)
*
* Copyright (C) 2000 Russell King
*
* Consistent memory allocators. Used for DMA devices that want to
* share uncached memory with the processor core. The function return
* is the virtual address and 'dma_handle' is the physical address.
* Mostly stolen from the ARM port, with some changes for PowerPC.
* -- Dan
*
* Reorganized to get rid of the arch-specific consistent_* functions
* and provide non-coherent implementations for the DMA API. -Matt
*
* Added in_interrupt() safe dma_alloc_coherent()/dma_free_coherent()
* implementation. This is pulled straight from ARM and barely
* modified. -Matt
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/highmem.h>
#include <linux/dma-mapping.h>
#include <asm/tlbflush.h>
#include "mmu_decl.h"
/*
* This address range defaults to a value that is safe for all
* platforms which currently set CONFIG_NOT_COHERENT_CACHE. It
* can be further configured for specific applications under
* the "Advanced Setup" menu. -Matt
*/
#define CONSISTENT_BASE (IOREMAP_TOP)
#define CONSISTENT_END (CONSISTENT_BASE + CONFIG_CONSISTENT_SIZE)
#define CONSISTENT_OFFSET(x) (((unsigned long)(x) - CONSISTENT_BASE) >> PAGE_SHIFT)
/*
* This is the page table (2MB) covering uncached, DMA consistent allocations
*/
static DEFINE_SPINLOCK(consistent_lock);
/*
* VM region handling support.
*
* This should become something generic, handling VM region allocations for
* vmalloc and similar (ioremap, module space, etc).
*
* I envisage vmalloc()'s supporting vm_struct becoming:
*
* struct vm_struct {
* struct vm_region region;
* unsigned long flags;
* struct page **pages;
* unsigned int nr_pages;
* unsigned long phys_addr;
* };
*
* get_vm_area() would then call vm_region_alloc with an appropriate
* struct vm_region head (eg):
*
* struct vm_region vmalloc_head = {
* .vm_list = LIST_HEAD_INIT(vmalloc_head.vm_list),
* .vm_start = VMALLOC_START,
* .vm_end = VMALLOC_END,
* };
*
* However, vmalloc_head.vm_start is variable (typically, it is dependent on
* the amount of RAM found at boot time.) I would imagine that get_vm_area()
* would have to initialise this each time prior to calling vm_region_alloc().
*/
struct ppc_vm_region {
struct list_head vm_list;
unsigned long vm_start;
unsigned long vm_end;
};
static struct ppc_vm_region consistent_head = {
.vm_list = LIST_HEAD_INIT(consistent_head.vm_list),
.vm_start = CONSISTENT_BASE,
.vm_end = CONSISTENT_END,
};
static struct ppc_vm_region *
ppc_vm_region_alloc(struct ppc_vm_region *head, size_t size, gfp_t gfp)
{
unsigned long addr = head->vm_start, end = head->vm_end - size;
unsigned long flags;
struct ppc_vm_region *c, *new;
new = kmalloc(sizeof(struct ppc_vm_region), gfp);
if (!new)
goto out;
spin_lock_irqsave(&consistent_lock, flags);
list_for_each_entry(c, &head->vm_list, vm_list) {
if ((addr + size) < addr)
goto nospc;
if ((addr + size) <= c->vm_start)
goto found;
addr = c->vm_end;
if (addr > end)
goto nospc;
}
found:
/*
* Insert this entry _before_ the one we found.
*/
list_add_tail(&new->vm_list, &c->vm_list);
new->vm_start = addr;
new->vm_end = addr + size;
spin_unlock_irqrestore(&consistent_lock, flags);
return new;
nospc:
spin_unlock_irqrestore(&consistent_lock, flags);
kfree(new);
out:
return NULL;
}
static struct ppc_vm_region *ppc_vm_region_find(struct ppc_vm_region *head, unsigned long addr)
{
struct ppc_vm_region *c;
list_for_each_entry(c, &head->vm_list, vm_list) {
if (c->vm_start == addr)
goto out;
}
c = NULL;
out:
return c;
}
/*
* Allocate DMA-coherent memory space and return both the kernel remapped
* virtual and bus address for that space.
*/
void *
__dma_alloc_coherent(struct device *dev, size_t size, dma_addr_t *handle, gfp_t gfp)
{
struct page *page;
struct ppc_vm_region *c;
unsigned long order;
u64 mask = ISA_DMA_THRESHOLD, limit;
if (dev) {
mask = dev->coherent_dma_mask;
/*
* Sanity check the DMA mask - it must be non-zero, and
* must be able to be satisfied by a DMA allocation.
*/
if (mask == 0) {
dev_warn(dev, "coherent DMA mask is unset\n");
goto no_page;
}
if ((~mask) & ISA_DMA_THRESHOLD) {
dev_warn(dev, "coherent DMA mask %#llx is smaller "
"than system GFP_DMA mask %#llx\n",
mask, (unsigned long long)ISA_DMA_THRESHOLD);
goto no_page;
}
}
size = PAGE_ALIGN(size);
limit = (mask + 1) & ~mask;
if ((limit && size >= limit) ||
size >= (CONSISTENT_END - CONSISTENT_BASE)) {
printk(KERN_WARNING "coherent allocation too big (requested %#x mask %#Lx)\n",
size, mask);
return NULL;
}
order = get_order(size);
/* Might be useful if we ever have a real legacy DMA zone... */
if (mask != 0xffffffff)
gfp |= GFP_DMA;
page = alloc_pages(gfp, order);
if (!page)
goto no_page;
/*
* Invalidate any data that might be lurking in the
* kernel direct-mapped region for device DMA.
*/
{
unsigned long kaddr = (unsigned long)page_address(page);
memset(page_address(page), 0, size);
flush_dcache_range(kaddr, kaddr + size);
}
/*
* Allocate a virtual address in the consistent mapping region.
*/
c = ppc_vm_region_alloc(&consistent_head, size,
gfp & ~(__GFP_DMA | __GFP_HIGHMEM));
if (c) {
unsigned long vaddr = c->vm_start;
struct page *end = page + (1 << order);
split_page(page, order);
/*
* Set the "dma handle"
*/
*handle = page_to_phys(page);
do {
SetPageReserved(page);
map_page(vaddr, page_to_phys(page),
pgprot_noncached(PAGE_KERNEL));
page++;
vaddr += PAGE_SIZE;
} while (size -= PAGE_SIZE);
/*
* Free the otherwise unused pages.
*/
while (page < end) {
__free_page(page);
page++;
}
return (void *)c->vm_start;
}
if (page)
__free_pages(page, order);
no_page:
return NULL;
}
EXPORT_SYMBOL(__dma_alloc_coherent);
/*
* free a page as defined by the above mapping.
*/
void __dma_free_coherent(size_t size, void *vaddr)
{
struct ppc_vm_region *c;
unsigned long flags, addr;
size = PAGE_ALIGN(size);
spin_lock_irqsave(&consistent_lock, flags);
c = ppc_vm_region_find(&consistent_head, (unsigned long)vaddr);
if (!c)
goto no_area;
if ((c->vm_end - c->vm_start) != size) {
printk(KERN_ERR "%s: freeing wrong coherent size (%ld != %d)\n",
__func__, c->vm_end - c->vm_start, size);
dump_stack();
size = c->vm_end - c->vm_start;
}
addr = c->vm_start;
do {
pte_t *ptep;
unsigned long pfn;
ptep = pte_offset_kernel(pmd_offset(pud_offset(pgd_offset_k(addr),
addr),
addr),
addr);
if (!pte_none(*ptep) && pte_present(*ptep)) {
pfn = pte_pfn(*ptep);
pte_clear(&init_mm, addr, ptep);
if (pfn_valid(pfn)) {
struct page *page = pfn_to_page(pfn);
ClearPageReserved(page);
__free_page(page);
}
}
addr += PAGE_SIZE;
} while (size -= PAGE_SIZE);
flush_tlb_kernel_range(c->vm_start, c->vm_end);
list_del(&c->vm_list);
spin_unlock_irqrestore(&consistent_lock, flags);
kfree(c);
return;
no_area:
spin_unlock_irqrestore(&consistent_lock, flags);
printk(KERN_ERR "%s: trying to free invalid coherent area: %p\n",
__func__, vaddr);
dump_stack();
}
EXPORT_SYMBOL(__dma_free_coherent);
/*
* make an area consistent.
*/
void __dma_sync(void *vaddr, size_t size, int direction)
{
unsigned long start = (unsigned long)vaddr;
unsigned long end = start + size;
switch (direction) {
case DMA_NONE:
BUG();
case DMA_FROM_DEVICE:
/*
* invalidate only when cache-line aligned otherwise there is
* the potential for discarding uncommitted data from the cache
*/
if ((start & (L1_CACHE_BYTES - 1)) || (size & (L1_CACHE_BYTES - 1)))
flush_dcache_range(start, end);
else
invalidate_dcache_range(start, end);
break;
case DMA_TO_DEVICE: /* writeback only */
clean_dcache_range(start, end);
break;
case DMA_BIDIRECTIONAL: /* writeback and invalidate */
flush_dcache_range(start, end);
break;
}
}
EXPORT_SYMBOL(__dma_sync);
#ifdef CONFIG_HIGHMEM
/*
* __dma_sync_page() implementation for systems using highmem.
* In this case, each page of a buffer must be kmapped/kunmapped
* in order to have a virtual address for __dma_sync(). This must
* not sleep so kmap_atomic()/kunmap_atomic() are used.
*
* Note: yes, it is possible and correct to have a buffer extend
* beyond the first page.
*/
static inline void __dma_sync_page_highmem(struct page *page,
unsigned long offset, size_t size, int direction)
{
size_t seg_size = min((size_t)(PAGE_SIZE - offset), size);
size_t cur_size = seg_size;
unsigned long flags, start, seg_offset = offset;
int nr_segs = 1 + ((size - seg_size) + PAGE_SIZE - 1)/PAGE_SIZE;
int seg_nr = 0;
local_irq_save(flags);
do {
start = (unsigned long)kmap_atomic(page + seg_nr,
KM_PPC_SYNC_PAGE) + seg_offset;
/* Sync this buffer segment */
__dma_sync((void *)start, seg_size, direction);
kunmap_atomic((void *)start, KM_PPC_SYNC_PAGE);
seg_nr++;
/* Calculate next buffer segment size */
seg_size = min((size_t)PAGE_SIZE, size - cur_size);
/* Add the segment size to our running total */
cur_size += seg_size;
seg_offset = 0;
} while (seg_nr < nr_segs);
local_irq_restore(flags);
}
#endif /* CONFIG_HIGHMEM */
/*
* __dma_sync_page makes memory consistent. identical to __dma_sync, but
* takes a struct page instead of a virtual address
*/
void __dma_sync_page(struct page *page, unsigned long offset,
size_t size, int direction)
{
#ifdef CONFIG_HIGHMEM
__dma_sync_page_highmem(page, offset, size, direction);
#else
unsigned long start = (unsigned long)page_address(page) + offset;
__dma_sync((void *)start, size, direction);
#endif
}
EXPORT_SYMBOL(__dma_sync_page);