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1162b070 VG |
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. | |
1162b070 VG |
17 | */ |
18 | ||
19 | #include <linux/dma-mapping.h> | |
20 | #include <linux/dma-debug.h> | |
21 | #include <linux/export.h> | |
f2b0b25a | 22 | #include <asm/cache.h> |
1162b070 VG |
23 | #include <asm/cacheflush.h> |
24 | ||
25 | /* | |
26 | * Helpers for Coherent DMA API. | |
27 | */ | |
28 | void *dma_alloc_noncoherent(struct device *dev, size_t size, | |
29 | dma_addr_t *dma_handle, gfp_t gfp) | |
30 | { | |
31 | void *paddr; | |
32 | ||
33 | /* This is linear addr (0x8000_0000 based) */ | |
34 | paddr = alloc_pages_exact(size, gfp); | |
35 | if (!paddr) | |
36 | return NULL; | |
37 | ||
38 | /* This is bus address, platform dependent */ | |
454bfda9 | 39 | *dma_handle = (dma_addr_t)paddr; |
1162b070 VG |
40 | |
41 | return paddr; | |
42 | } | |
43 | EXPORT_SYMBOL(dma_alloc_noncoherent); | |
44 | ||
45 | void dma_free_noncoherent(struct device *dev, size_t size, void *vaddr, | |
46 | dma_addr_t dma_handle) | |
47 | { | |
454bfda9 | 48 | free_pages_exact((void *)dma_handle, size); |
1162b070 VG |
49 | } |
50 | EXPORT_SYMBOL(dma_free_noncoherent); | |
51 | ||
52 | void *dma_alloc_coherent(struct device *dev, size_t size, | |
53 | dma_addr_t *dma_handle, gfp_t gfp) | |
54 | { | |
55 | void *paddr, *kvaddr; | |
56 | ||
f2b0b25a AB |
57 | /* |
58 | * IOC relies on all data (even coherent DMA data) being in cache | |
59 | * Thus allocate normal cached memory | |
60 | * | |
61 | * The gains with IOC are two pronged: | |
62 | * -For streaming data, elides needs for cache maintenance, saving | |
63 | * cycles in flush code, and bus bandwidth as all the lines of a | |
64 | * buffer need to be flushed out to memory | |
65 | * -For coherent data, Read/Write to buffers terminate early in cache | |
66 | * (vs. always going to memory - thus are faster) | |
67 | */ | |
fd0881a2 | 68 | if (is_isa_arcv2() && ioc_exists) |
f2b0b25a AB |
69 | return dma_alloc_noncoherent(dev, size, dma_handle, gfp); |
70 | ||
1162b070 VG |
71 | /* This is linear addr (0x8000_0000 based) */ |
72 | paddr = alloc_pages_exact(size, gfp); | |
73 | if (!paddr) | |
74 | return NULL; | |
75 | ||
76 | /* This is kernel Virtual address (0x7000_0000 based) */ | |
77 | kvaddr = ioremap_nocache((unsigned long)paddr, size); | |
f718c2ef VG |
78 | if (kvaddr == NULL) |
79 | return NULL; | |
1162b070 VG |
80 | |
81 | /* This is bus address, platform dependent */ | |
454bfda9 | 82 | *dma_handle = (dma_addr_t)paddr; |
1162b070 | 83 | |
795f4558 VG |
84 | /* |
85 | * Evict any existing L1 and/or L2 lines for the backing page | |
86 | * in case it was used earlier as a normal "cached" page. | |
87 | * Yeah this bit us - STAR 9000898266 | |
88 | * | |
89 | * Although core does call flush_cache_vmap(), it gets kvaddr hence | |
90 | * can't be used to efficiently flush L1 and/or L2 which need paddr | |
91 | * Currently flush_cache_vmap nukes the L1 cache completely which | |
92 | * will be optimized as a separate commit | |
93 | */ | |
94 | dma_cache_wback_inv((unsigned long)paddr, size); | |
95 | ||
1162b070 VG |
96 | return kvaddr; |
97 | } | |
98 | EXPORT_SYMBOL(dma_alloc_coherent); | |
99 | ||
100 | void dma_free_coherent(struct device *dev, size_t size, void *kvaddr, | |
101 | dma_addr_t dma_handle) | |
102 | { | |
fd0881a2 | 103 | if (is_isa_arcv2() && ioc_exists) |
f2b0b25a AB |
104 | return dma_free_noncoherent(dev, size, kvaddr, dma_handle); |
105 | ||
1162b070 VG |
106 | iounmap((void __force __iomem *)kvaddr); |
107 | ||
454bfda9 | 108 | free_pages_exact((void *)dma_handle, size); |
1162b070 VG |
109 | } |
110 | EXPORT_SYMBOL(dma_free_coherent); | |
111 | ||
112 | /* | |
113 | * Helper for streaming DMA... | |
114 | */ | |
115 | void __arc_dma_cache_sync(unsigned long paddr, size_t size, | |
116 | enum dma_data_direction dir) | |
117 | { | |
118 | __inline_dma_cache_sync(paddr, size, dir); | |
119 | } | |
120 | EXPORT_SYMBOL(__arc_dma_cache_sync); |