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 <linux/export.h>
30#include <sound/core.h>
31#include <asm/dma.h>
32
33/**
34 * snd_dma_program - program an ISA DMA transfer
35 * @dma: the dma number
36 * @addr: the physical address of the buffer
37 * @size: the DMA transfer size
38 * @mode: the DMA transfer mode, DMA_MODE_XXX
39 *
40 * Programs an ISA DMA transfer for the given buffer.
41 */
42void snd_dma_program(unsigned long dma,
43		     unsigned long addr, unsigned int size,
44                     unsigned short mode)
45{
46	unsigned long flags;
47
48	flags = claim_dma_lock();
49	disable_dma(dma);
50	clear_dma_ff(dma);
51	set_dma_mode(dma, mode);
52	set_dma_addr(dma, addr);
53	set_dma_count(dma, size);
54	if (!(mode & DMA_MODE_NO_ENABLE))
55		enable_dma(dma);
56	release_dma_lock(flags);
57}
58
59EXPORT_SYMBOL(snd_dma_program);
60
61/**
62 * snd_dma_disable - stop the ISA DMA transfer
63 * @dma: the dma number
64 *
65 * Stops the ISA DMA transfer.
66 */
67void snd_dma_disable(unsigned long dma)
68{
69	unsigned long flags;
70
71	flags = claim_dma_lock();
72	clear_dma_ff(dma);
73	disable_dma(dma);
74	release_dma_lock(flags);
75}
76
77EXPORT_SYMBOL(snd_dma_disable);
78
79/**
80 * snd_dma_pointer - return the current pointer to DMA transfer buffer in bytes
81 * @dma: the dma number
82 * @size: the dma transfer size
83 *
84 * Return: The current pointer in DMA transfer buffer in bytes.
85 */
86unsigned int snd_dma_pointer(unsigned long dma, unsigned int size)
87{
88	unsigned long flags;
89	unsigned int result, result1;
90
91	flags = claim_dma_lock();
92	clear_dma_ff(dma);
93	if (!isa_dma_bridge_buggy)
94		disable_dma(dma);
95	result = get_dma_residue(dma);
96	/*
97	 * HACK - read the counter again and choose higher value in order to
98	 * avoid reading during counter lower byte roll over if the
99	 * isa_dma_bridge_buggy is set.
100	 */
101	result1 = get_dma_residue(dma);
102	if (!isa_dma_bridge_buggy)
103		enable_dma(dma);
104	release_dma_lock(flags);
105	if (unlikely(result < result1))
106		result = result1;
107#ifdef CONFIG_SND_DEBUG
108	if (result > size)
109		pr_err("ALSA: pointer (0x%x) for DMA #%ld is greater than transfer size (0x%x)\n", result, dma, size);
110#endif
111	if (result >= size || result == 0)
112		return 0;
113	else
114		return size - result;
115}
116
117EXPORT_SYMBOL(snd_dma_pointer);
118