diff options
Diffstat (limited to 'arch/arc/mm/dma.c')
| -rw-r--r-- | arch/arc/mm/dma.c | 47 |
1 files changed, 32 insertions, 15 deletions
diff --git a/arch/arc/mm/dma.c b/arch/arc/mm/dma.c index 6cf1d924209a..4b428a449300 100644 --- a/arch/arc/mm/dma.c +++ b/arch/arc/mm/dma.c @@ -28,23 +28,18 @@ static void *arc_dma_alloc(struct device *dev, size_t size, struct page *page; phys_addr_t paddr; void *kvaddr; + int need_coh = 1, need_kvaddr = 0; page = alloc_pages(gfp, order); if (!page) return NULL; - /* This is linear addr (0x8000_0000 based) */ - paddr = page_to_phys(page); - - /* For now bus address is exactly same as paddr */ - *dma_handle = paddr; - /* * IOC relies on all data (even coherent DMA data) being in cache * Thus allocate normal cached memory * * The gains with IOC are two pronged: - * -For streaming data, elides needs for cache maintenance, saving + * -For streaming data, elides need for cache maintenance, saving * cycles in flush code, and bus bandwidth as all the lines of a * buffer need to be flushed out to memory * -For coherent data, Read/Write to buffers terminate early in cache @@ -52,13 +47,31 @@ static void *arc_dma_alloc(struct device *dev, size_t size, */ if ((is_isa_arcv2() && ioc_exists) || dma_get_attr(DMA_ATTR_NON_CONSISTENT, attrs)) - return paddr; + need_coh = 0; + + /* + * - A coherent buffer needs MMU mapping to enforce non-cachability + * - A highmem page needs a virtual handle (hence MMU mapping) + * independent of cachability + */ + if (PageHighMem(page) || need_coh) + need_kvaddr = 1; + + /* This is linear addr (0x8000_0000 based) */ + paddr = page_to_phys(page); + + /* For now bus address is exactly same as paddr */ + *dma_handle = paddr; /* This is kernel Virtual address (0x7000_0000 based) */ - kvaddr = ioremap_nocache((unsigned long)paddr, size); - if (kvaddr == NULL) { - __free_pages(page, order); - return NULL; + if (need_kvaddr) { + kvaddr = ioremap_nocache((unsigned long)paddr, size); + if (kvaddr == NULL) { + __free_pages(page, order); + return NULL; + } + } else { + kvaddr = (void *)paddr; } /* @@ -71,7 +84,8 @@ static void *arc_dma_alloc(struct device *dev, size_t size, * Currently flush_cache_vmap nukes the L1 cache completely which * will be optimized as a separate commit */ - dma_cache_wback_inv((unsigned long)paddr, size); + if (need_coh) + dma_cache_wback_inv((unsigned long)paddr, size); return kvaddr; } @@ -80,9 +94,12 @@ static void arc_dma_free(struct device *dev, size_t size, void *vaddr, dma_addr_t dma_handle, struct dma_attrs *attrs) { struct page *page = virt_to_page(dma_handle); + int is_non_coh = 1; + + is_non_coh = dma_get_attr(DMA_ATTR_NON_CONSISTENT, attrs) || + (is_isa_arcv2() && ioc_exists); - if (!dma_get_attr(DMA_ATTR_NON_CONSISTENT, attrs) && - !(is_isa_arcv2() && ioc_exists)) + if (PageHighMem(page) || !is_non_coh) iounmap((void __force __iomem *)vaddr); __free_pages(page, get_order(size)); |