From 7a9a32a9533fa01de911e1d056142ddd27360782 Mon Sep 17 00:00:00 2001 From: Russell King Date: Thu, 19 Nov 2009 15:31:07 +0000 Subject: [PATCH] ARM: dma-mapping: functions to allocate/free a coherent buffer Signed-off-by: Russell King Acked-by: Greg Ungerer --- arch/arm/mm/dma-mapping.c | 110 +++++++++++++++++++++++--------------- 1 file changed, 66 insertions(+), 44 deletions(-) diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c index c54f1acf92c..dab2d7f04ad 100644 --- a/arch/arm/mm/dma-mapping.c +++ b/arch/arm/mm/dma-mapping.c @@ -63,6 +63,68 @@ static u64 get_coherent_dma_mask(struct device *dev) return mask; } +/* + * Allocate a DMA buffer for 'dev' of size 'size' using the + * specified gfp mask. Note that 'size' must be page aligned. + */ +static struct page *__dma_alloc_buffer(struct device *dev, size_t size, gfp_t gfp) +{ + unsigned long order = get_order(size); + struct page *page, *p, *e; + void *ptr; + u64 mask = get_coherent_dma_mask(dev); + +#ifdef CONFIG_DMA_API_DEBUG + u64 limit = (mask + 1) & ~mask; + if (limit && size >= limit) { + dev_warn(dev, "coherent allocation too big (requested %#x mask %#llx)\n", + size, mask); + return NULL; + } +#endif + + if (!mask) + return NULL; + + if (mask < 0xffffffffULL) + gfp |= GFP_DMA; + + page = alloc_pages(gfp, order); + if (!page) + return NULL; + + /* + * Now split the huge page and free the excess pages + */ + split_page(page, order); + for (p = page + (size >> PAGE_SHIFT), e = page + (1 << order); p < e; p++) + __free_page(p); + + /* + * Ensure that the allocated pages are zeroed, and that any data + * lurking in the kernel direct-mapped region is invalidated. + */ + ptr = page_address(page); + memset(ptr, 0, size); + dmac_flush_range(ptr, ptr + size); + outer_flush_range(__pa(ptr), __pa(ptr) + size); + + return page; +} + +/* + * Free a DMA buffer. 'size' must be page aligned. + */ +static void __dma_free_buffer(struct page *page, size_t size) +{ + struct page *e = page + (size >> PAGE_SHIFT); + + while (page < e) { + __free_page(page); + page++; + } +} + #ifdef CONFIG_MMU /* * These are the page tables (2MB each) covering uncached, DMA consistent allocations @@ -88,9 +150,6 @@ __dma_alloc(struct device *dev, size_t size, dma_addr_t *handle, gfp_t gfp, { struct page *page; struct arm_vmregion *c; - unsigned long order; - u64 mask = get_coherent_dma_mask(dev); - u64 limit; if (!consistent_pte[0]) { printk(KERN_ERR "%s: not initialised\n", __func__); @@ -98,37 +157,12 @@ __dma_alloc(struct device *dev, size_t size, dma_addr_t *handle, gfp_t gfp, return NULL; } - if (!mask) - goto no_page; - size = PAGE_ALIGN(size); - limit = (mask + 1) & ~mask; - if (limit && size >= limit) { - printk(KERN_WARNING "coherent allocation too big " - "(requested %#x mask %#llx)\n", size, mask); - goto no_page; - } - order = get_order(size); - - if (mask < 0xffffffffULL) - gfp |= GFP_DMA; - - page = alloc_pages(gfp, order); + page = __dma_alloc_buffer(dev, size, gfp); if (!page) goto no_page; - /* - * Invalidate any data that might be lurking in the - * kernel direct-mapped region for device DMA. - */ - { - void *ptr = page_address(page); - memset(ptr, 0, size); - dmac_flush_range(ptr, ptr + size); - outer_flush_range(__pa(ptr), __pa(ptr) + size); - } - /* * Allocate a virtual address in the consistent mapping region. */ @@ -136,15 +170,12 @@ __dma_alloc(struct device *dev, size_t size, dma_addr_t *handle, gfp_t gfp, gfp & ~(__GFP_DMA | __GFP_HIGHMEM)); if (c) { pte_t *pte; - struct page *end = page + (1 << order); int idx = CONSISTENT_PTE_INDEX(c->vm_start); u32 off = CONSISTENT_OFFSET(c->vm_start) & (PTRS_PER_PTE-1); pte = consistent_pte[idx] + off; c->vm_pages = page; - split_page(page, order); - /* * Set the "dma handle" */ @@ -167,19 +198,11 @@ __dma_alloc(struct device *dev, size_t size, dma_addr_t *handle, gfp_t gfp, } } 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); + __dma_free_buffer(page, size); no_page: *handle = ~0; return NULL; @@ -357,12 +380,9 @@ void dma_free_coherent(struct device *dev, size_t size, void *cpu_addr, dma_addr * 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); @@ -370,6 +390,8 @@ void dma_free_coherent(struct device *dev, size_t size, void *cpu_addr, dma_addr flush_tlb_kernel_range(c->vm_start, c->vm_end); arm_vmregion_free(&consistent_head, c); + + __dma_free_buffer(dma_to_page(dev, handle), size); return; no_area: