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1 | /* |
2 | * ISA DMA support functions |
3 | * Copyright (c) by Jaroslav Kysela <perex@perex.cz> |
4 | * |
5 | * |
6 | * This program is free software; you can redistribute it and/or modify |
7 | * it under the terms of the GNU General Public License as published by |
8 | * the Free Software Foundation; either version 2 of the License, or |
9 | * (at your option) any later version. |
10 | * |
11 | * This program is distributed in the hope that it will be useful, |
12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
14 | * GNU General Public License for more details. |
15 | * |
16 | * You should have received a copy of the GNU General Public License |
17 | * along with this program; if not, write to the Free Software |
18 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
19 | * |
20 | */ |
21 | |
22 | /* |
23 | * Defining following add some delay. Maybe this helps for some broken |
24 | * ISA DMA controllers. |
25 | */ |
26 | |
27 | #undef HAVE_REALLY_SLOW_DMA_CONTROLLER |
28 | |
29 | #include <sound/core.h> |
30 | #include <asm/dma.h> |
31 | |
32 | /** |
33 | * snd_dma_program - program an ISA DMA transfer |
34 | * @dma: the dma number |
35 | * @addr: the physical address of the buffer |
36 | * @size: the DMA transfer size |
37 | * @mode: the DMA transfer mode, DMA_MODE_XXX |
38 | * |
39 | * Programs an ISA DMA transfer for the given buffer. |
40 | */ |
41 | void snd_dma_program(unsigned long dma, |
42 | unsigned long addr, unsigned int size, |
43 | unsigned short mode) |
44 | { |
45 | unsigned long flags; |
46 | |
47 | flags = claim_dma_lock(); |
48 | disable_dma(dma); |
49 | clear_dma_ff(dma); |
50 | set_dma_mode(dma, mode); |
51 | set_dma_addr(dma, addr); |
52 | set_dma_count(dma, size); |
53 | if (!(mode & DMA_MODE_NO_ENABLE)) |
54 | enable_dma(dma); |
55 | release_dma_lock(flags); |
56 | } |
57 | |
58 | EXPORT_SYMBOL(snd_dma_program); |
59 | |
60 | /** |
61 | * snd_dma_disable - stop the ISA DMA transfer |
62 | * @dma: the dma number |
63 | * |
64 | * Stops the ISA DMA transfer. |
65 | */ |
66 | void snd_dma_disable(unsigned long dma) |
67 | { |
68 | unsigned long flags; |
69 | |
70 | flags = claim_dma_lock(); |
71 | clear_dma_ff(dma); |
72 | disable_dma(dma); |
73 | release_dma_lock(flags); |
74 | } |
75 | |
76 | EXPORT_SYMBOL(snd_dma_disable); |
77 | |
78 | /** |
79 | * snd_dma_pointer - return the current pointer to DMA transfer buffer in bytes |
80 | * @dma: the dma number |
81 | * @size: the dma transfer size |
82 | * |
83 | * Returns the current pointer in DMA tranfer buffer in bytes |
84 | */ |
85 | unsigned int snd_dma_pointer(unsigned long dma, unsigned int size) |
86 | { |
87 | unsigned long flags; |
88 | unsigned int result, result1; |
89 | |
90 | flags = claim_dma_lock(); |
91 | clear_dma_ff(dma); |
92 | if (!isa_dma_bridge_buggy) |
93 | disable_dma(dma); |
94 | result = get_dma_residue(dma); |
95 | /* |
96 | * HACK - read the counter again and choose higher value in order to |
97 | * avoid reading during counter lower byte roll over if the |
98 | * isa_dma_bridge_buggy is set. |
99 | */ |
100 | result1 = get_dma_residue(dma); |
101 | if (!isa_dma_bridge_buggy) |
102 | enable_dma(dma); |
103 | release_dma_lock(flags); |
104 | if (unlikely(result < result1)) |
105 | result = result1; |
106 | #ifdef CONFIG_SND_DEBUG |
107 | if (result > size) |
108 | snd_printk(KERN_ERR "pointer (0x%x) for DMA #%ld is greater than transfer size (0x%x)\n", result, dma, size); |
109 | #endif |
110 | if (result >= size || result == 0) |
111 | return 0; |
112 | else |
113 | return size - result; |
114 | } |
115 | |
116 | EXPORT_SYMBOL(snd_dma_pointer); |
117 |
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