diff options
Diffstat (limited to 'kernel/arch/arc/mm/dma.c')
-rw-r--r-- | kernel/arch/arc/mm/dma.c | 94 |
1 files changed, 94 insertions, 0 deletions
diff --git a/kernel/arch/arc/mm/dma.c b/kernel/arch/arc/mm/dma.c new file mode 100644 index 000000000..12cc6485b --- /dev/null +++ b/kernel/arch/arc/mm/dma.c @@ -0,0 +1,94 @@ +/* + * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com) + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ + +/* + * DMA Coherent API Notes + * + * I/O is inherently non-coherent on ARC. So a coherent DMA buffer is + * implemented by accessintg it using a kernel virtual address, with + * Cache bit off in the TLB entry. + * + * The default DMA address == Phy address which is 0x8000_0000 based. + * A platform/device can make it zero based, by over-riding + * plat_{dma,kernel}_addr_to_{kernel,dma} + */ + +#include <linux/dma-mapping.h> +#include <linux/dma-debug.h> +#include <linux/export.h> +#include <asm/cacheflush.h> + +/* + * Helpers for Coherent DMA API. + */ +void *dma_alloc_noncoherent(struct device *dev, size_t size, + dma_addr_t *dma_handle, gfp_t gfp) +{ + void *paddr; + + /* This is linear addr (0x8000_0000 based) */ + paddr = alloc_pages_exact(size, gfp); + if (!paddr) + return NULL; + + /* This is bus address, platform dependent */ + *dma_handle = plat_kernel_addr_to_dma(dev, paddr); + + return paddr; +} +EXPORT_SYMBOL(dma_alloc_noncoherent); + +void dma_free_noncoherent(struct device *dev, size_t size, void *vaddr, + dma_addr_t dma_handle) +{ + free_pages_exact((void *)plat_dma_addr_to_kernel(dev, dma_handle), + size); +} +EXPORT_SYMBOL(dma_free_noncoherent); + +void *dma_alloc_coherent(struct device *dev, size_t size, + dma_addr_t *dma_handle, gfp_t gfp) +{ + void *paddr, *kvaddr; + + /* This is linear addr (0x8000_0000 based) */ + paddr = alloc_pages_exact(size, gfp); + if (!paddr) + return NULL; + + /* This is kernel Virtual address (0x7000_0000 based) */ + kvaddr = ioremap_nocache((unsigned long)paddr, size); + if (kvaddr != NULL) + memset(kvaddr, 0, size); + + /* This is bus address, platform dependent */ + *dma_handle = plat_kernel_addr_to_dma(dev, paddr); + + return kvaddr; +} +EXPORT_SYMBOL(dma_alloc_coherent); + +void dma_free_coherent(struct device *dev, size_t size, void *kvaddr, + dma_addr_t dma_handle) +{ + iounmap((void __force __iomem *)kvaddr); + + free_pages_exact((void *)plat_dma_addr_to_kernel(dev, dma_handle), + size); +} +EXPORT_SYMBOL(dma_free_coherent); + +/* + * Helper for streaming DMA... + */ +void __arc_dma_cache_sync(unsigned long paddr, size_t size, + enum dma_data_direction dir) +{ + __inline_dma_cache_sync(paddr, size, dir); +} +EXPORT_SYMBOL(__arc_dma_cache_sync); |