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