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linux/arch/arm/mm/consistent.c

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/*
* linux/arch/arm/mm/consistent.c
*
* Copyright (C) 2000-2004 Russell King
*
* 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.
*
* DMA uncached mapping support.
*/
#include <linux/module.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/errno.h>
#include <linux/list.h>
#include <linux/init.h>
#include <linux/device.h>
#include <linux/dma-mapping.h>
#include <asm/cacheflush.h>
#include <asm/io.h>
#include <asm/tlbflush.h>
#define CONSISTENT_BASE (0xffc00000)
#define CONSISTENT_END (0xffe00000)
#define CONSISTENT_OFFSET(x) (((unsigned long)(x) - CONSISTENT_BASE) >> PAGE_SHIFT)
/*
* This is the page table (2MB) covering uncached, DMA consistent allocations
*/
static pte_t *consistent_pte;
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 vm_region {
struct list_head vm_list;
unsigned long vm_start;
unsigned long vm_end;
struct page *vm_pages;
};
static struct vm_region consistent_head = {
.vm_list = LIST_HEAD_INIT(consistent_head.vm_list),
.vm_start = CONSISTENT_BASE,
.vm_end = CONSISTENT_END,
};
static struct vm_region *
vm_region_alloc(struct vm_region *head, size_t size, int gfp)
{
unsigned long addr = head->vm_start, end = head->vm_end - size;
unsigned long flags;
struct vm_region *c, *new;
new = kmalloc(sizeof(struct 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 vm_region *vm_region_find(struct vm_region *head, unsigned long addr)
{
struct 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;
}
#ifdef CONFIG_HUGETLB_PAGE
#error ARM Coherent DMA allocator does not (yet) support huge TLB
#endif
static void *
__dma_alloc(struct device *dev, size_t size, dma_addr_t *handle, int gfp,
pgprot_t prot)
{
struct page *page;
struct vm_region *c;
unsigned long order;
u64 mask = ISA_DMA_THRESHOLD, limit;
if (!consistent_pte) {
printk(KERN_ERR "%s: not initialised\n", __func__);
dump_stack();
return NULL;
}
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;
}
}
/*
* Sanity check the allocation size.
*/
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 %#llx)\n", size, mask);
goto no_page;
}
order = get_order(size);
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);
dmac_flush_range(kaddr, kaddr + size);
}
/*
* Allocate a virtual address in the consistent mapping region.
*/
c = vm_region_alloc(&consistent_head, size,
gfp & ~(__GFP_DMA | __GFP_HIGHMEM));
if (c) {
pte_t *pte = consistent_pte + CONSISTENT_OFFSET(c->vm_start);
struct page *end = page + (1 << order);
c->vm_pages = page;
/*
* Set the "dma handle"
*/
*handle = page_to_dma(dev, page);
do {
BUG_ON(!pte_none(*pte));
set_page_count(page, 1);
/*
* x86 does not mark the pages reserved...
*/
SetPageReserved(page);
set_pte(pte, mk_pte(page, prot));
page++;
pte++;
} while (size -= PAGE_SIZE);
/*
* Free the otherwise unused pages.
*/
while (page < end) {
set_page_count(page, 1);
__free_page(page);
page++;
}
return (void *)c->vm_start;
}
if (page)
__free_pages(page, order);
no_page:
*handle = ~0;
return NULL;
}
/*
* 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, int gfp)
{
return __dma_alloc(dev, size, handle, gfp,
pgprot_noncached(pgprot_kernel));
}
EXPORT_SYMBOL(dma_alloc_coherent);
/*
* Allocate a writecombining region, in much the same way as
* dma_alloc_coherent above.
*/
void *
dma_alloc_writecombine(struct device *dev, size_t size, dma_addr_t *handle, int gfp)
{
return __dma_alloc(dev, size, handle, gfp,
pgprot_writecombine(pgprot_kernel));
}
EXPORT_SYMBOL(dma_alloc_writecombine);
static int dma_mmap(struct device *dev, struct vm_area_struct *vma,
void *cpu_addr, dma_addr_t dma_addr, size_t size)
{
unsigned long flags, user_size, kern_size;
struct vm_region *c;
int ret = -ENXIO;
user_size = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
spin_lock_irqsave(&consistent_lock, flags);
c = vm_region_find(&consistent_head, (unsigned long)cpu_addr);
spin_unlock_irqrestore(&consistent_lock, flags);
if (c) {
unsigned long off = vma->vm_pgoff;
kern_size = (c->vm_end - c->vm_start) >> PAGE_SHIFT;
if (off < kern_size &&
user_size <= (kern_size - off)) {
vma->vm_flags |= VM_RESERVED;
ret = remap_pfn_range(vma, vma->vm_start,
page_to_pfn(c->vm_pages) + off,
user_size << PAGE_SHIFT,
vma->vm_page_prot);
}
}
return ret;
}
int dma_mmap_coherent(struct device *dev, struct vm_area_struct *vma,
void *cpu_addr, dma_addr_t dma_addr, size_t size)
{
vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
return dma_mmap(dev, vma, cpu_addr, dma_addr, size);
}
EXPORT_SYMBOL(dma_mmap_coherent);
int dma_mmap_writecombine(struct device *dev, struct vm_area_struct *vma,
void *cpu_addr, dma_addr_t dma_addr, size_t size)
{
vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot);
return dma_mmap(dev, vma, cpu_addr, dma_addr, size);
}
EXPORT_SYMBOL(dma_mmap_writecombine);
/*
* free a page as defined by the above mapping.
*/
void dma_free_coherent(struct device *dev, size_t size, void *cpu_addr, dma_addr_t handle)
{
struct vm_region *c;
unsigned long flags, addr;
pte_t *ptep;
size = PAGE_ALIGN(size);
spin_lock_irqsave(&consistent_lock, flags);
c = vm_region_find(&consistent_head, (unsigned long)cpu_addr);
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;
}
ptep = consistent_pte + CONSISTENT_OFFSET(c->vm_start);
addr = c->vm_start;
do {
pte_t pte = ptep_get_and_clear(&init_mm, addr, ptep);
unsigned long pfn;
ptep++;
addr += PAGE_SIZE;
if (!pte_none(pte) && pte_present(pte)) {
pfn = pte_pfn(pte);
if (pfn_valid(pfn)) {
struct page *page = pfn_to_page(pfn);
/*
* x86 does not mark the pages reserved...
*/
ClearPageReserved(page);
__free_page(page);
continue;
}
}
printk(KERN_CRIT "%s: bad page in kernel page table\n",
__func__);
} 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__, cpu_addr);
dump_stack();
}
EXPORT_SYMBOL(dma_free_coherent);
/*
* Initialise the consistent memory allocation.
*/
static int __init consistent_init(void)
{
pgd_t *pgd;
pmd_t *pmd;
pte_t *pte;
int ret = 0;
spin_lock(&init_mm.page_table_lock);
do {
pgd = pgd_offset(&init_mm, CONSISTENT_BASE);
pmd = pmd_alloc(&init_mm, pgd, CONSISTENT_BASE);
if (!pmd) {
printk(KERN_ERR "%s: no pmd tables\n", __func__);
ret = -ENOMEM;
break;
}
WARN_ON(!pmd_none(*pmd));
pte = pte_alloc_kernel(&init_mm, pmd, CONSISTENT_BASE);
if (!pte) {
printk(KERN_ERR "%s: no pte tables\n", __func__);
ret = -ENOMEM;
break;
}
consistent_pte = pte;
} while (0);
spin_unlock(&init_mm.page_table_lock);
return ret;
}
core_initcall(consistent_init);
/*
* Make an area consistent for devices.
*/
void consistent_sync(void *vaddr, size_t size, int direction)
{
unsigned long start = (unsigned long)vaddr;
unsigned long end = start + size;
switch (direction) {
case DMA_FROM_DEVICE: /* invalidate only */
dmac_inv_range(start, end);
break;
case DMA_TO_DEVICE: /* writeback only */
dmac_clean_range(start, end);
break;
case DMA_BIDIRECTIONAL: /* writeback and invalidate */
dmac_flush_range(start, end);
break;
default:
BUG();
}
}
EXPORT_SYMBOL(consistent_sync);
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