1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * atmel-pcm-dma.c -- ALSA PCM DMA support for the Atmel SoC.
4 *
5 * Copyright (C) 2012 Atmel
6 *
7 * Author: Bo Shen <voice.shen@atmel.com>
8 *
9 * Based on atmel-pcm by:
10 * Sedji Gaouaou <sedji.gaouaou@atmel.com>
11 * Copyright 2008 Atmel
12 */
13
14#include <linux/module.h>
15#include <linux/init.h>
16#include <linux/platform_device.h>
17#include <linux/slab.h>
18#include <linux/dma-mapping.h>
19#include <linux/dmaengine.h>
20#include <linux/atmel-ssc.h>
21
22#include <sound/core.h>
23#include <sound/pcm.h>
24#include <sound/pcm_params.h>
25#include <sound/soc.h>
26#include <sound/dmaengine_pcm.h>
27
28#include "atmel-pcm.h"
29
30/*--------------------------------------------------------------------------*\
31 * Hardware definition
32\*--------------------------------------------------------------------------*/
33static const struct snd_pcm_hardware atmel_pcm_dma_hardware = {
34 .info = SNDRV_PCM_INFO_MMAP |
35 SNDRV_PCM_INFO_MMAP_VALID |
36 SNDRV_PCM_INFO_INTERLEAVED |
37 SNDRV_PCM_INFO_RESUME |
38 SNDRV_PCM_INFO_PAUSE,
39 .period_bytes_min = 256, /* lighting DMA overhead */
40 .period_bytes_max = 2 * 0xffff, /* if 2 bytes format */
41 .periods_min = 8,
42 .periods_max = 1024, /* no limit */
43 .buffer_bytes_max = 512 * 1024,
44};
45
46/*
47 * atmel_pcm_dma_irq: SSC interrupt handler for DMAENGINE enabled SSC
48 *
49 * We use DMAENGINE to send/receive data to/from SSC so this ISR is only to
50 * check if any overrun occured.
51 */
52static void atmel_pcm_dma_irq(u32 ssc_sr,
53 struct snd_pcm_substream *substream)
54{
55 struct snd_soc_pcm_runtime *rtd = snd_soc_substream_to_rtd(substream);
56 struct atmel_pcm_dma_params *prtd;
57
58 prtd = snd_soc_dai_get_dma_data(snd_soc_rtd_to_cpu(rtd, 0), substream);
59
60 if (ssc_sr & prtd->mask->ssc_error) {
61 if (snd_pcm_running(substream))
62 pr_warn("atmel-pcm: buffer %s on %s (SSC_SR=%#x)\n",
63 substream->stream == SNDRV_PCM_STREAM_PLAYBACK
64 ? "underrun" : "overrun", prtd->name,
65 ssc_sr);
66
67 /* stop RX and capture: will be enabled again at restart */
68 ssc_writex(prtd->ssc->regs, SSC_CR, prtd->mask->ssc_disable);
69 snd_pcm_stop_xrun(substream);
70
71 /* now drain RHR and read status to remove xrun condition */
72 ssc_readx(prtd->ssc->regs, SSC_RHR);
73 ssc_readx(prtd->ssc->regs, SSC_SR);
74 }
75}
76
77static int atmel_pcm_configure_dma(struct snd_pcm_substream *substream,
78 struct snd_pcm_hw_params *params, struct dma_slave_config *slave_config)
79{
80 struct snd_soc_pcm_runtime *rtd = snd_soc_substream_to_rtd(substream);
81 struct atmel_pcm_dma_params *prtd;
82 struct ssc_device *ssc;
83 int ret;
84
85 prtd = snd_soc_dai_get_dma_data(snd_soc_rtd_to_cpu(rtd, 0), substream);
86 ssc = prtd->ssc;
87
88 ret = snd_hwparams_to_dma_slave_config(substream, params, slave_config);
89 if (ret) {
90 pr_err("atmel-pcm: hwparams to dma slave configure failed\n");
91 return ret;
92 }
93
94 slave_config->dst_addr = ssc->phybase + SSC_THR;
95 slave_config->dst_maxburst = 1;
96
97 slave_config->src_addr = ssc->phybase + SSC_RHR;
98 slave_config->src_maxburst = 1;
99
100 prtd->dma_intr_handler = atmel_pcm_dma_irq;
101
102 return 0;
103}
104
105static const struct snd_dmaengine_pcm_config atmel_dmaengine_pcm_config = {
106 .prepare_slave_config = atmel_pcm_configure_dma,
107 .pcm_hardware = &atmel_pcm_dma_hardware,
108 .prealloc_buffer_size = 64 * 1024,
109};
110
111int atmel_pcm_dma_platform_register(struct device *dev)
112{
113 return devm_snd_dmaengine_pcm_register(dev,
114 config: &atmel_dmaengine_pcm_config, flags: 0);
115}
116EXPORT_SYMBOL(atmel_pcm_dma_platform_register);
117
118MODULE_AUTHOR("Bo Shen <voice.shen@atmel.com>");
119MODULE_DESCRIPTION("Atmel DMA based PCM module");
120MODULE_LICENSE("GPL");
121

source code of linux/sound/soc/atmel/atmel-pcm-dma.c