Neither CMA nor noncoherent allocations support atomic allocations. Add a dedicated atomic pool to support this.
Change-Id: I46c8fdffe5e0687403d42b37643137c8cf344259 Signed-off-by: Laura Abbott <lau...@codeaurora.org> --- v2: Various bug fixes pointed out by David and Ritesh (CMA dependency, swapping coherent, noncoherent). I'm still not sure how to address the devicetree suggestion by Will [1][2]. I added the devicetree mailing list this time around to get more input on this. [1] http://lists.infradead.org/pipermail/linux-arm-kernel/2014-April/249180.html [2] http://lists.infradead.org/pipermail/linux-arm-kernel/2014-April/249528.html --- arch/arm64/mm/dma-mapping.c | 192 +++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 190 insertions(+), 2 deletions(-) diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c index c851eb4..792d43c 100644 --- a/arch/arm64/mm/dma-mapping.c +++ b/arch/arm64/mm/dma-mapping.c @@ -41,6 +41,110 @@ static pgprot_t __get_dma_pgprot(struct dma_attrs *attrs, pgprot_t prot, return prot; } +#define DEFAULT_DMA_COHERENT_POOL_SIZE SZ_256K + +struct dma_pool { + size_t size; + spinlock_t lock; + void *coherent_vaddr; + void *noncoherent_vaddr; + unsigned long *bitmap; + unsigned long nr_pages; + struct page **pages; +}; + +static struct dma_pool atomic_pool = { + .size = DEFAULT_DMA_COHERENT_POOL_SIZE, +}; + +static int __init early_coherent_pool(char *p) +{ + atomic_pool.size = memparse(p, &p); + return 0; +} +early_param("coherent_pool", early_coherent_pool); + +static void *__alloc_from_pool(size_t size, struct page **ret_page, + bool coherent) +{ + struct dma_pool *pool = &atomic_pool; + unsigned int count = PAGE_ALIGN(size) >> PAGE_SHIFT; + unsigned int pageno; + unsigned long flags; + void *ptr = NULL; + unsigned long align_mask; + void *pool_start = coherent ? pool->coherent_vaddr : + pool->noncoherent_vaddr; + + if (!pool->coherent_vaddr || !pool->noncoherent_vaddr) { + WARN(1, "Atomic pool not initialised!\n"); + return NULL; + } + + /* + * Align the region allocation - allocations from pool are rather + * small, so align them to their order in pages, minimum is a page + * size. This helps reduce fragmentation of the DMA space. + */ + align_mask = (1 << get_order(size)) - 1; + + spin_lock_irqsave(&pool->lock, flags); + pageno = bitmap_find_next_zero_area(pool->bitmap, pool->nr_pages, + 0, count, align_mask); + if (pageno < pool->nr_pages) { + bitmap_set(pool->bitmap, pageno, count); + ptr = pool_start + PAGE_SIZE * pageno; + *ret_page = pool->pages[pageno]; + } else { + pr_err_once("ERROR: %u KiB atomic DMA coherent pool is too small!\n" + "Please increase it with coherent_pool= kernel parameter!\n", + (unsigned)pool->size / 1024); + } + spin_unlock_irqrestore(&pool->lock, flags); + + return ptr; +} + +static bool __in_atomic_pool(void *start, size_t size, void *pool_start) +{ + struct dma_pool *pool = &atomic_pool; + void *end = start + size; + void *pool_end = pool_start + pool->size; + + if (start < pool_start || start >= pool_end) + return false; + + if (end <= pool_end) + return true; + + WARN(1, "Wrong coherent size(%p-%p) from atomic pool(%p-%p)\n", + start, end - 1, pool_start, pool_end - 1); + + return false; +} + +static int __free_from_pool(void *start, size_t size, bool coherent) +{ + struct dma_pool *pool = &atomic_pool; + unsigned long pageno, count; + unsigned long flags; + void *pool_start = coherent ? pool->coherent_vaddr : + pool->noncoherent_vaddr; + + if (!__in_atomic_pool(start, size, pool_start)) + return 0; + + pageno = (start - pool_start) >> PAGE_SHIFT; + count = size >> PAGE_SHIFT; + + spin_lock_irqsave(&pool->lock, flags); + bitmap_clear(pool->bitmap, pageno, count); + spin_unlock_irqrestore(&pool->lock, flags); + + return 1; +} + + static void *__dma_alloc_coherent(struct device *dev, size_t size, dma_addr_t *dma_handle, gfp_t flags, struct dma_attrs *attrs) @@ -53,7 +157,16 @@ static void *__dma_alloc_coherent(struct device *dev, size_t size, if (IS_ENABLED(CONFIG_ZONE_DMA) && dev->coherent_dma_mask <= DMA_BIT_MASK(32)) flags |= GFP_DMA; - if (IS_ENABLED(CONFIG_DMA_CMA)) { + + if (!(flags & __GFP_WAIT)) { + struct page *page = NULL; + void *addr = __alloc_from_pool(size, &page, true); + + if (addr) + *dma_handle = phys_to_dma(dev, page_to_phys(page)); + + return addr; + } else if (IS_ENABLED(CONFIG_DMA_CMA)) { struct page *page; size = PAGE_ALIGN(size); @@ -78,7 +191,9 @@ static void __dma_free_coherent(struct device *dev, size_t size, return; } - if (IS_ENABLED(CONFIG_DMA_CMA)) { + if (__free_from_pool(vaddr, size, true)) { + return; + } else if (IS_ENABLED(CONFIG_DMA_CMA)) { phys_addr_t paddr = dma_to_phys(dev, dma_handle); dma_release_from_contiguous(dev, @@ -100,9 +215,21 @@ static void *__dma_alloc_noncoherent(struct device *dev, size_t size, size = PAGE_ALIGN(size); order = get_order(size); + if (!(flags & __GFP_WAIT)) { + struct page *page = NULL; + void *addr = __alloc_from_pool(size, &page, false); + + if (addr) + *dma_handle = phys_to_dma(dev, page_to_phys(page)); + + return addr; + + } + ptr = __dma_alloc_coherent(dev, size, dma_handle, flags, attrs); if (!ptr) goto no_mem; + map = kmalloc(sizeof(struct page *) << order, flags & ~GFP_DMA); if (!map) goto no_map; @@ -135,6 +262,8 @@ static void __dma_free_noncoherent(struct device *dev, size_t size, { void *swiotlb_addr = phys_to_virt(dma_to_phys(dev, dma_handle)); + if (__free_from_pool(vaddr, size, false)) + return; vunmap(vaddr); __dma_free_coherent(dev, size, swiotlb_addr, dma_handle, attrs); } @@ -332,6 +461,65 @@ static struct notifier_block amba_bus_nb = { extern int swiotlb_late_init_with_default_size(size_t default_size); +static int __init atomic_pool_init(void) +{ + struct dma_pool *pool = &atomic_pool; + pgprot_t prot = pgprot_writecombine(pgprot_default); + unsigned long nr_pages = pool->size >> PAGE_SHIFT; + unsigned long *bitmap; + struct page *page; + struct page **pages; + int bitmap_size = BITS_TO_LONGS(nr_pages) * sizeof(long); + + bitmap = kzalloc(bitmap_size, GFP_KERNEL); + if (!bitmap) + goto no_bitmap; + + pages = kzalloc(nr_pages * sizeof(struct page *), GFP_KERNEL); + if (!pages) + goto no_pages; + + if (IS_ENABLED(CONFIG_CMA)) + page = dma_alloc_from_contiguous(NULL, nr_pages, + get_order(pool->size)); + else + page = alloc_pages(GFP_KERNEL, get_order(pool->size)); + + + if (page) { + int i; + void *addr = page_address(page); + + memset(addr, 0, pool->size); + __dma_flush_range(addr, addr + pool->size); + + for (i = 0; i < nr_pages; i++) + pages[i] = page + i; + + spin_lock_init(&pool->lock); + pool->pages = pages; + pool->noncoherent_vaddr = vmap(pages, nr_pages, VM_MAP, prot); + if (pool->noncoherent_vaddr == NULL) + goto out; + pool->coherent_vaddr = addr; + pool->bitmap = bitmap; + pool->nr_pages = nr_pages; + pr_info("DMA: preallocated %u KiB pool for atomic allocations\n", + (unsigned)pool->size / 1024); + return 0; + } + +out: + kfree(pages); +no_pages: + kfree(bitmap); +no_bitmap: + pr_err("DMA: failed to allocate %u KiB pool for atomic coherent allocation\n", + (unsigned)pool->size / 1024); + return -ENOMEM; +} +postcore_initcall(atomic_pool_init); + static int __init swiotlb_late_init(void) { size_t swiotlb_size = min(SZ_64M, MAX_ORDER_NR_PAGES << PAGE_SHIFT); -- The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, hosted by The Linux Foundation -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
