/* * Dynamic DMA mapping support * * Copyright 2005-2009 Analog Devices Inc. * * Licensed under the GPL-2 or later */ #include <linux/types.h> #include <linux/gfp.h> #include <linux/string.h> #include <linux/spinlock.h> #include <linux/dma-mapping.h> #include <linux/scatterlist.h> #include <linux/export.h> static spinlock_t dma_page_lock; static unsigned long *dma_page; static unsigned int dma_pages; static unsigned long dma_base; static unsigned long dma_size; static unsigned int dma_initialized; static void dma_alloc_init(unsigned long start, unsigned long end) { spin_lock_init(&dma_page_lock); dma_initialized = 0; dma_page = (unsigned long *)__get_free_page(GFP_KERNEL); memset(dma_page, 0, PAGE_SIZE); dma_base = PAGE_ALIGN(start); dma_size = PAGE_ALIGN(end) - PAGE_ALIGN(start); dma_pages = dma_size >> PAGE_SHIFT; memset((void *)dma_base, 0, DMA_UNCACHED_REGION); dma_initialized = 1; printk(KERN_INFO "%s: dma_page @ 0x%p - %d pages at 0x%08lx\n", __func__, dma_page, dma_pages, dma_base); } static inline unsigned int get_pages(size_t size) { return ((size - 1) >> PAGE_SHIFT) + 1; } static unsigned long __alloc_dma_pages(unsigned int pages) { unsigned long ret = 0, flags; int i, count = 0; if (dma_initialized == 0) dma_alloc_init(_ramend - DMA_UNCACHED_REGION, _ramend); spin_lock_irqsave(&dma_page_lock, flags); for (i = 0; i < dma_pages;) { if (test_bit(i++, dma_page) == 0) { if (++count == pages) { while (count--) __set_bit(--i, dma_page); ret = dma_base + (i << PAGE_SHIFT); break; } } else count = 0; } spin_unlock_irqrestore(&dma_page_lock, flags); return ret; } static void __free_dma_pages(unsigned long addr, unsigned int pages) { unsigned long page = (addr - dma_base) >> PAGE_SHIFT; unsigned long flags; int i; if ((page + pages) > dma_pages) { printk(KERN_ERR "%s: freeing outside range.\n", __func__); BUG(); } spin_lock_irqsave(&dma_page_lock, flags); for (i = page; i < page + pages; i++) __clear_bit(i, dma_page); spin_unlock_irqrestore(&dma_page_lock, flags); } void *dma_alloc_coherent(struct device *dev, size_t size, dma_addr_t *dma_handle, gfp_t gfp) { void *ret; ret = (void *)__alloc_dma_pages(get_pages(size)); if (ret) { memset(ret, 0, size); *dma_handle = virt_to_phys(ret); } return ret; } EXPORT_SYMBOL(dma_alloc_coherent); void dma_free_coherent(struct device *dev, size_t size, void *vaddr, dma_addr_t dma_handle) { __free_dma_pages((unsigned long)vaddr, get_pages(size)); } EXPORT_SYMBOL(dma_free_coherent); /* * Streaming DMA mappings */ void __dma_sync(dma_addr_t addr, size_t size, enum dma_data_direction dir) { __dma_sync_inline(addr, size, dir); } EXPORT_SYMBOL(__dma_sync); int dma_map_sg(struct device *dev, struct scatterlist *sg, int nents, enum dma_data_direction direction) { int i; for (i = 0; i < nents; i++, sg++) { sg->dma_address = (dma_addr_t) sg_virt(sg); __dma_sync(sg_dma_address(sg), sg_dma_len(sg), direction); } return nents; } EXPORT_SYMBOL(dma_map_sg); void dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg, int nelems, enum dma_data_direction direction) { int i; for (i = 0; i < nelems; i++, sg++) { sg->dma_address = (dma_addr_t) sg_virt(sg); __dma_sync(sg_dma_address(sg), sg_dma_len(sg), direction); } } EXPORT_SYMBOL(dma_sync_sg_for_device);