1 /* 2 * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com) 3 * 4 * This program is free software; you can redistribute it and/or modify 5 * it under the terms of the GNU General Public License version 2 as 6 * published by the Free Software Foundation. 7 */ 8 9 /* 10 * DMA Coherent API Notes 11 * 12 * I/O is inherently non-coherent on ARC. So a coherent DMA buffer is 13 * implemented by accessintg it using a kernel virtual address, with 14 * Cache bit off in the TLB entry. 15 * 16 * The default DMA address == Phy address which is 0x8000_0000 based. 17 */ 18 19 #include <linux/dma-mapping.h> 20 #include <linux/dma-debug.h> 21 #include <linux/export.h> 22 #include <asm/cacheflush.h> 23 24 /* 25 * Helpers for Coherent DMA API. 26 */ 27 void *dma_alloc_noncoherent(struct device *dev, size_t size, 28 dma_addr_t *dma_handle, gfp_t gfp) 29 { 30 void *paddr; 31 32 /* This is linear addr (0x8000_0000 based) */ 33 paddr = alloc_pages_exact(size, gfp); 34 if (!paddr) 35 return NULL; 36 37 /* This is bus address, platform dependent */ 38 *dma_handle = (dma_addr_t)paddr; 39 40 return paddr; 41 } 42 EXPORT_SYMBOL(dma_alloc_noncoherent); 43 44 void dma_free_noncoherent(struct device *dev, size_t size, void *vaddr, 45 dma_addr_t dma_handle) 46 { 47 free_pages_exact((void *)dma_handle, size); 48 } 49 EXPORT_SYMBOL(dma_free_noncoherent); 50 51 void *dma_alloc_coherent(struct device *dev, size_t size, 52 dma_addr_t *dma_handle, gfp_t gfp) 53 { 54 void *paddr, *kvaddr; 55 56 /* This is linear addr (0x8000_0000 based) */ 57 paddr = alloc_pages_exact(size, gfp); 58 if (!paddr) 59 return NULL; 60 61 /* This is kernel Virtual address (0x7000_0000 based) */ 62 kvaddr = ioremap_nocache((unsigned long)paddr, size); 63 if (kvaddr == NULL) 64 return NULL; 65 66 /* This is bus address, platform dependent */ 67 *dma_handle = (dma_addr_t)paddr; 68 69 /* 70 * Evict any existing L1 and/or L2 lines for the backing page 71 * in case it was used earlier as a normal "cached" page. 72 * Yeah this bit us - STAR 9000898266 73 * 74 * Although core does call flush_cache_vmap(), it gets kvaddr hence 75 * can't be used to efficiently flush L1 and/or L2 which need paddr 76 * Currently flush_cache_vmap nukes the L1 cache completely which 77 * will be optimized as a separate commit 78 */ 79 dma_cache_wback_inv((unsigned long)paddr, size); 80 81 return kvaddr; 82 } 83 EXPORT_SYMBOL(dma_alloc_coherent); 84 85 void dma_free_coherent(struct device *dev, size_t size, void *kvaddr, 86 dma_addr_t dma_handle) 87 { 88 iounmap((void __force __iomem *)kvaddr); 89 90 free_pages_exact((void *)dma_handle, size); 91 } 92 EXPORT_SYMBOL(dma_free_coherent); 93 94 /* 95 * Helper for streaming DMA... 96 */ 97 void __arc_dma_cache_sync(unsigned long paddr, size_t size, 98 enum dma_data_direction dir) 99 { 100 __inline_dma_cache_sync(paddr, size, dir); 101 } 102 EXPORT_SYMBOL(__arc_dma_cache_sync); 103