1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0-or-later
2*4882a593Smuzhiyun /*
3*4882a593Smuzhiyun * ISA DMA support functions
4*4882a593Smuzhiyun * Copyright (c) by Jaroslav Kysela <perex@perex.cz>
5*4882a593Smuzhiyun */
6*4882a593Smuzhiyun
7*4882a593Smuzhiyun /*
8*4882a593Smuzhiyun * Defining following add some delay. Maybe this helps for some broken
9*4882a593Smuzhiyun * ISA DMA controllers.
10*4882a593Smuzhiyun */
11*4882a593Smuzhiyun
12*4882a593Smuzhiyun #undef HAVE_REALLY_SLOW_DMA_CONTROLLER
13*4882a593Smuzhiyun
14*4882a593Smuzhiyun #include <linux/export.h>
15*4882a593Smuzhiyun #include <sound/core.h>
16*4882a593Smuzhiyun #include <asm/dma.h>
17*4882a593Smuzhiyun
18*4882a593Smuzhiyun /**
19*4882a593Smuzhiyun * snd_dma_program - program an ISA DMA transfer
20*4882a593Smuzhiyun * @dma: the dma number
21*4882a593Smuzhiyun * @addr: the physical address of the buffer
22*4882a593Smuzhiyun * @size: the DMA transfer size
23*4882a593Smuzhiyun * @mode: the DMA transfer mode, DMA_MODE_XXX
24*4882a593Smuzhiyun *
25*4882a593Smuzhiyun * Programs an ISA DMA transfer for the given buffer.
26*4882a593Smuzhiyun */
snd_dma_program(unsigned long dma,unsigned long addr,unsigned int size,unsigned short mode)27*4882a593Smuzhiyun void snd_dma_program(unsigned long dma,
28*4882a593Smuzhiyun unsigned long addr, unsigned int size,
29*4882a593Smuzhiyun unsigned short mode)
30*4882a593Smuzhiyun {
31*4882a593Smuzhiyun unsigned long flags;
32*4882a593Smuzhiyun
33*4882a593Smuzhiyun flags = claim_dma_lock();
34*4882a593Smuzhiyun disable_dma(dma);
35*4882a593Smuzhiyun clear_dma_ff(dma);
36*4882a593Smuzhiyun set_dma_mode(dma, mode);
37*4882a593Smuzhiyun set_dma_addr(dma, addr);
38*4882a593Smuzhiyun set_dma_count(dma, size);
39*4882a593Smuzhiyun if (!(mode & DMA_MODE_NO_ENABLE))
40*4882a593Smuzhiyun enable_dma(dma);
41*4882a593Smuzhiyun release_dma_lock(flags);
42*4882a593Smuzhiyun }
43*4882a593Smuzhiyun EXPORT_SYMBOL(snd_dma_program);
44*4882a593Smuzhiyun
45*4882a593Smuzhiyun /**
46*4882a593Smuzhiyun * snd_dma_disable - stop the ISA DMA transfer
47*4882a593Smuzhiyun * @dma: the dma number
48*4882a593Smuzhiyun *
49*4882a593Smuzhiyun * Stops the ISA DMA transfer.
50*4882a593Smuzhiyun */
snd_dma_disable(unsigned long dma)51*4882a593Smuzhiyun void snd_dma_disable(unsigned long dma)
52*4882a593Smuzhiyun {
53*4882a593Smuzhiyun unsigned long flags;
54*4882a593Smuzhiyun
55*4882a593Smuzhiyun flags = claim_dma_lock();
56*4882a593Smuzhiyun clear_dma_ff(dma);
57*4882a593Smuzhiyun disable_dma(dma);
58*4882a593Smuzhiyun release_dma_lock(flags);
59*4882a593Smuzhiyun }
60*4882a593Smuzhiyun EXPORT_SYMBOL(snd_dma_disable);
61*4882a593Smuzhiyun
62*4882a593Smuzhiyun /**
63*4882a593Smuzhiyun * snd_dma_pointer - return the current pointer to DMA transfer buffer in bytes
64*4882a593Smuzhiyun * @dma: the dma number
65*4882a593Smuzhiyun * @size: the dma transfer size
66*4882a593Smuzhiyun *
67*4882a593Smuzhiyun * Return: The current pointer in DMA transfer buffer in bytes.
68*4882a593Smuzhiyun */
snd_dma_pointer(unsigned long dma,unsigned int size)69*4882a593Smuzhiyun unsigned int snd_dma_pointer(unsigned long dma, unsigned int size)
70*4882a593Smuzhiyun {
71*4882a593Smuzhiyun unsigned long flags;
72*4882a593Smuzhiyun unsigned int result, result1;
73*4882a593Smuzhiyun
74*4882a593Smuzhiyun flags = claim_dma_lock();
75*4882a593Smuzhiyun clear_dma_ff(dma);
76*4882a593Smuzhiyun if (!isa_dma_bridge_buggy)
77*4882a593Smuzhiyun disable_dma(dma);
78*4882a593Smuzhiyun result = get_dma_residue(dma);
79*4882a593Smuzhiyun /*
80*4882a593Smuzhiyun * HACK - read the counter again and choose higher value in order to
81*4882a593Smuzhiyun * avoid reading during counter lower byte roll over if the
82*4882a593Smuzhiyun * isa_dma_bridge_buggy is set.
83*4882a593Smuzhiyun */
84*4882a593Smuzhiyun result1 = get_dma_residue(dma);
85*4882a593Smuzhiyun if (!isa_dma_bridge_buggy)
86*4882a593Smuzhiyun enable_dma(dma);
87*4882a593Smuzhiyun release_dma_lock(flags);
88*4882a593Smuzhiyun if (unlikely(result < result1))
89*4882a593Smuzhiyun result = result1;
90*4882a593Smuzhiyun #ifdef CONFIG_SND_DEBUG
91*4882a593Smuzhiyun if (result > size)
92*4882a593Smuzhiyun pr_err("ALSA: pointer (0x%x) for DMA #%ld is greater than transfer size (0x%x)\n", result, dma, size);
93*4882a593Smuzhiyun #endif
94*4882a593Smuzhiyun if (result >= size || result == 0)
95*4882a593Smuzhiyun return 0;
96*4882a593Smuzhiyun else
97*4882a593Smuzhiyun return size - result;
98*4882a593Smuzhiyun }
99*4882a593Smuzhiyun EXPORT_SYMBOL(snd_dma_pointer);
100