2 * linux/arch/arm/mm/consistent.c
4 * Copyright (C) 2000-2004 Russell King
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
10 * DMA uncached mapping support.
12 #include <linux/module.h>
14 #include <linux/slab.h>
15 #include <linux/errno.h>
16 #include <linux/list.h>
17 #include <linux/init.h>
18 #include <linux/device.h>
19 #include <linux/dma-mapping.h>
21 #include <asm/cacheflush.h>
23 #include <asm/tlbflush.h>
25 #define CONSISTENT_BASE (0xffc00000)
26 #define CONSISTENT_END (0xffe00000)
27 #define CONSISTENT_OFFSET(x) (((unsigned long)(x) - CONSISTENT_BASE) >> PAGE_SHIFT)
30 * This is the page table (2MB) covering uncached, DMA consistent allocations
32 static pte_t
*consistent_pte
;
33 static DEFINE_SPINLOCK(consistent_lock
);
36 * VM region handling support.
38 * This should become something generic, handling VM region allocations for
39 * vmalloc and similar (ioremap, module space, etc).
41 * I envisage vmalloc()'s supporting vm_struct becoming:
44 * struct vm_region region;
45 * unsigned long flags;
46 * struct page **pages;
47 * unsigned int nr_pages;
48 * unsigned long phys_addr;
51 * get_vm_area() would then call vm_region_alloc with an appropriate
52 * struct vm_region head (eg):
54 * struct vm_region vmalloc_head = {
55 * .vm_list = LIST_HEAD_INIT(vmalloc_head.vm_list),
56 * .vm_start = VMALLOC_START,
57 * .vm_end = VMALLOC_END,
60 * However, vmalloc_head.vm_start is variable (typically, it is dependent on
61 * the amount of RAM found at boot time.) I would imagine that get_vm_area()
62 * would have to initialise this each time prior to calling vm_region_alloc().
65 struct list_head vm_list
;
66 unsigned long vm_start
;
68 struct page
*vm_pages
;
72 static struct vm_region consistent_head
= {
73 .vm_list
= LIST_HEAD_INIT(consistent_head
.vm_list
),
74 .vm_start
= CONSISTENT_BASE
,
75 .vm_end
= CONSISTENT_END
,
78 static struct vm_region
*
79 vm_region_alloc(struct vm_region
*head
, size_t size
, gfp_t gfp
)
81 unsigned long addr
= head
->vm_start
, end
= head
->vm_end
- size
;
83 struct vm_region
*c
, *new;
85 new = kmalloc(sizeof(struct vm_region
), gfp
);
89 spin_lock_irqsave(&consistent_lock
, flags
);
91 list_for_each_entry(c
, &head
->vm_list
, vm_list
) {
92 if ((addr
+ size
) < addr
)
94 if ((addr
+ size
) <= c
->vm_start
)
103 * Insert this entry _before_ the one we found.
105 list_add_tail(&new->vm_list
, &c
->vm_list
);
106 new->vm_start
= addr
;
107 new->vm_end
= addr
+ size
;
110 spin_unlock_irqrestore(&consistent_lock
, flags
);
114 spin_unlock_irqrestore(&consistent_lock
, flags
);
120 static struct vm_region
*vm_region_find(struct vm_region
*head
, unsigned long addr
)
124 list_for_each_entry(c
, &head
->vm_list
, vm_list
) {
125 if (c
->vm_active
&& c
->vm_start
== addr
)
133 #ifdef CONFIG_HUGETLB_PAGE
134 #error ARM Coherent DMA allocator does not (yet) support huge TLB
138 __dma_alloc(struct device
*dev
, size_t size
, dma_addr_t
*handle
, gfp_t gfp
,
144 u64 mask
= ISA_DMA_THRESHOLD
, limit
;
146 if (!consistent_pte
) {
147 printk(KERN_ERR
"%s: not initialised\n", __func__
);
153 mask
= dev
->coherent_dma_mask
;
156 * Sanity check the DMA mask - it must be non-zero, and
157 * must be able to be satisfied by a DMA allocation.
160 dev_warn(dev
, "coherent DMA mask is unset\n");
164 if ((~mask
) & ISA_DMA_THRESHOLD
) {
165 dev_warn(dev
, "coherent DMA mask %#llx is smaller "
166 "than system GFP_DMA mask %#llx\n",
167 mask
, (unsigned long long)ISA_DMA_THRESHOLD
);
173 * Sanity check the allocation size.
175 size
= PAGE_ALIGN(size
);
176 limit
= (mask
+ 1) & ~mask
;
177 if ((limit
&& size
>= limit
) ||
178 size
>= (CONSISTENT_END
- CONSISTENT_BASE
)) {
179 printk(KERN_WARNING
"coherent allocation too big "
180 "(requested %#x mask %#llx)\n", size
, mask
);
184 order
= get_order(size
);
186 if (mask
!= 0xffffffff)
189 page
= alloc_pages(gfp
, order
);
194 * Invalidate any data that might be lurking in the
195 * kernel direct-mapped region for device DMA.
198 unsigned long kaddr
= (unsigned long)page_address(page
);
199 memset(page_address(page
), 0, size
);
200 dmac_flush_range(kaddr
, kaddr
+ size
);
204 * Allocate a virtual address in the consistent mapping region.
206 c
= vm_region_alloc(&consistent_head
, size
,
207 gfp
& ~(__GFP_DMA
| __GFP_HIGHMEM
));
209 pte_t
*pte
= consistent_pte
+ CONSISTENT_OFFSET(c
->vm_start
);
210 struct page
*end
= page
+ (1 << order
);
215 * Set the "dma handle"
217 *handle
= page_to_dma(dev
, page
);
220 BUG_ON(!pte_none(*pte
));
222 set_page_count(page
, 1);
224 * x86 does not mark the pages reserved...
226 SetPageReserved(page
);
227 set_pte(pte
, mk_pte(page
, prot
));
230 } while (size
-= PAGE_SIZE
);
233 * Free the otherwise unused pages.
236 set_page_count(page
, 1);
241 return (void *)c
->vm_start
;
245 __free_pages(page
, order
);
252 * Allocate DMA-coherent memory space and return both the kernel remapped
253 * virtual and bus address for that space.
256 dma_alloc_coherent(struct device
*dev
, size_t size
, dma_addr_t
*handle
, gfp_t gfp
)
258 return __dma_alloc(dev
, size
, handle
, gfp
,
259 pgprot_noncached(pgprot_kernel
));
261 EXPORT_SYMBOL(dma_alloc_coherent
);
264 * Allocate a writecombining region, in much the same way as
265 * dma_alloc_coherent above.
268 dma_alloc_writecombine(struct device
*dev
, size_t size
, dma_addr_t
*handle
, gfp_t gfp
)
270 return __dma_alloc(dev
, size
, handle
, gfp
,
271 pgprot_writecombine(pgprot_kernel
));
273 EXPORT_SYMBOL(dma_alloc_writecombine
);
275 static int dma_mmap(struct device
*dev
, struct vm_area_struct
*vma
,
276 void *cpu_addr
, dma_addr_t dma_addr
, size_t size
)
278 unsigned long flags
, user_size
, kern_size
;
282 user_size
= (vma
->vm_end
- vma
->vm_start
) >> PAGE_SHIFT
;
284 spin_lock_irqsave(&consistent_lock
, flags
);
285 c
= vm_region_find(&consistent_head
, (unsigned long)cpu_addr
);
286 spin_unlock_irqrestore(&consistent_lock
, flags
);
289 unsigned long off
= vma
->vm_pgoff
;
291 kern_size
= (c
->vm_end
- c
->vm_start
) >> PAGE_SHIFT
;
293 if (off
< kern_size
&&
294 user_size
<= (kern_size
- off
)) {
295 vma
->vm_flags
|= VM_RESERVED
;
296 ret
= remap_pfn_range(vma
, vma
->vm_start
,
297 page_to_pfn(c
->vm_pages
) + off
,
298 user_size
<< PAGE_SHIFT
,
306 int dma_mmap_coherent(struct device
*dev
, struct vm_area_struct
*vma
,
307 void *cpu_addr
, dma_addr_t dma_addr
, size_t size
)
309 vma
->vm_page_prot
= pgprot_noncached(vma
->vm_page_prot
);
310 return dma_mmap(dev
, vma
, cpu_addr
, dma_addr
, size
);
312 EXPORT_SYMBOL(dma_mmap_coherent
);
314 int dma_mmap_writecombine(struct device
*dev
, struct vm_area_struct
*vma
,
315 void *cpu_addr
, dma_addr_t dma_addr
, size_t size
)
317 vma
->vm_page_prot
= pgprot_writecombine(vma
->vm_page_prot
);
318 return dma_mmap(dev
, vma
, cpu_addr
, dma_addr
, size
);
320 EXPORT_SYMBOL(dma_mmap_writecombine
);
323 * free a page as defined by the above mapping.
324 * Must not be called with IRQs disabled.
326 void dma_free_coherent(struct device
*dev
, size_t size
, void *cpu_addr
, dma_addr_t handle
)
329 unsigned long flags
, addr
;
332 WARN_ON(irqs_disabled());
334 size
= PAGE_ALIGN(size
);
336 spin_lock_irqsave(&consistent_lock
, flags
);
337 c
= vm_region_find(&consistent_head
, (unsigned long)cpu_addr
);
342 spin_unlock_irqrestore(&consistent_lock
, flags
);
344 if ((c
->vm_end
- c
->vm_start
) != size
) {
345 printk(KERN_ERR
"%s: freeing wrong coherent size (%ld != %d)\n",
346 __func__
, c
->vm_end
- c
->vm_start
, size
);
348 size
= c
->vm_end
- c
->vm_start
;
351 ptep
= consistent_pte
+ CONSISTENT_OFFSET(c
->vm_start
);
354 pte_t pte
= ptep_get_and_clear(&init_mm
, addr
, ptep
);
360 if (!pte_none(pte
) && pte_present(pte
)) {
363 if (pfn_valid(pfn
)) {
364 struct page
*page
= pfn_to_page(pfn
);
367 * x86 does not mark the pages reserved...
369 ClearPageReserved(page
);
376 printk(KERN_CRIT
"%s: bad page in kernel page table\n",
378 } while (size
-= PAGE_SIZE
);
380 flush_tlb_kernel_range(c
->vm_start
, c
->vm_end
);
382 spin_lock_irqsave(&consistent_lock
, flags
);
383 list_del(&c
->vm_list
);
384 spin_unlock_irqrestore(&consistent_lock
, flags
);
390 spin_unlock_irqrestore(&consistent_lock
, flags
);
391 printk(KERN_ERR
"%s: trying to free invalid coherent area: %p\n",
395 EXPORT_SYMBOL(dma_free_coherent
);
398 * Initialise the consistent memory allocation.
400 static int __init
consistent_init(void)
408 pgd
= pgd_offset(&init_mm
, CONSISTENT_BASE
);
409 pmd
= pmd_alloc(&init_mm
, pgd
, CONSISTENT_BASE
);
411 printk(KERN_ERR
"%s: no pmd tables\n", __func__
);
415 WARN_ON(!pmd_none(*pmd
));
417 pte
= pte_alloc_kernel(pmd
, CONSISTENT_BASE
);
419 printk(KERN_ERR
"%s: no pte tables\n", __func__
);
424 consistent_pte
= pte
;
430 core_initcall(consistent_init
);
433 * Make an area consistent for devices.
435 void consistent_sync(void *vaddr
, size_t size
, int direction
)
437 unsigned long start
= (unsigned long)vaddr
;
438 unsigned long end
= start
+ size
;
441 case DMA_FROM_DEVICE
: /* invalidate only */
442 dmac_inv_range(start
, end
);
444 case DMA_TO_DEVICE
: /* writeback only */
445 dmac_clean_range(start
, end
);
447 case DMA_BIDIRECTIONAL
: /* writeback and invalidate */
448 dmac_flush_range(start
, end
);
454 EXPORT_SYMBOL(consistent_sync
);