RK3399 Android7.1虚拟声卡驱动添加的步骤分享

Platform: RK3399
OS: Android 7.1
Kernel: v4.4.83

需求：

当前默认一个普通的codec已经无法满足需求了，如回声消除，降噪，唤醒等功能。

RK3399平台的I2S0通道提供最高8路通道录音支持。如果拿到一个麦克阵列，那么可以添加到此路通道上。

I2S1就接普通codec.

代码实现：

firefly平台也有对应的实现，可参考。

这部分代码是由rockchip罗工实现，感谢他，也让我对audio有了进一步了解。

/*

rk_pcm_codec.c -- Rockchip PCM codecs driver
Copyright (c) 2016, ROCKCHIP CORPORATION. All rights reserved.
Author: Xiaotan Luo <lxt@rock-chips.com>

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License version 2 and
only version 2 as published by the Free Software Foundation.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
*/
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/slab.h>
#include <linux/of.h>
#include <linux/of_gpio.h>
#include <sound/soc.h>
#include <sound/pcm.h>
#include <sound/initval.h>

#if 1
#define DBG(x...) printk(KERN_INFO "rk_pcm_codec :"x)
#else
#define DBG(x...) do { } while (0)
#endif
#define FORMATS (SNDRV_PCM_FMTBIT_S16_LE | SNDRV_PCM_FMTBIT_S20_3LE |
SNDRV_PCM_FMTBIT_S24_LE| SNDRV_PCM_FMTBIT_S32_LE)
struct snd_soc_dai_driver sph0645lm4h_card_dai = {
.name = "rockchip-sph0645lm4h-card-hifi",
.capture = {
.stream_name = "HiFi Capture",
.channels_min = 2,
.channels_max = 8,
.rates = (
SNDRV_PCM_RATE_8000|
SNDRV_PCM_RATE_16000|
SNDRV_PCM_RATE_32000 |
SNDRV_PCM_RATE_44100 |
SNDRV_PCM_RATE_48000 |
SNDRV_PCM_RATE_96000 |
SNDRV_PCM_RATE_192000),
.formats = FORMATS,
},

};

static struct snd_soc_codec_driver soc_codec_dev_sph0645lm4h_card;

static int rockchip_sph0645lm4h_card_audio_probe(struct platform_device *pdev)
{
int ret;

//set dev name to driver->name for sound card register
//printk("%s,%s\n",__FILE__,__FUNCTION__);
dev_set_name(&pdev->dev, "%s", pdev->dev.driver->name);

ret = snd_soc_register_codec(&pdev->dev,
	&soc_codec_dev_sph0645lm4h_card,
	&sph0645lm4h_card_dai, 1);

if (ret)
	printk("%s() register card failed:%d\n", __FUNCTION__, ret);
printk("---------------------rockchip_pcm_card_audio_probe111-------------------\n");
return ret;

}

static int rockchip_sph0645lm4h_card_audio_remove(struct platform_device *pdev)
{
snd_soc_unregister_codec(&pdev->dev);

return 0;

}

#ifdef CONFIG_OF
static const struct of_device_id rockchip_sph0645lm4h_card_of_match[] = {
{ .compatible = "rockchip-sph0645lm4h-codec", },
{},
};
MODULE_DEVICE_TABLE(of, rockchip_sph0645lm4h_card_of_match);
#endif /* CONFIG_OF */

static struct platform_driver rockchip_sph0645lm4h_card_audio_driver = {
.driver = {
.name = "rockchip-sph0645lm4h-codec",
.owner = THIS_MODULE,
.of_match_table = of_match_ptr(rockchip_sph0645lm4h_card_of_match),
},
.probe = rockchip_sph0645lm4h_card_audio_probe,
.remove = rockchip_sph0645lm4h_card_audio_remove,
};

module_platform_driver(rockchip_sph0645lm4h_card_audio_driver);

MODULE_DESCRIPTION("ASoC Rockchip PCM codec driver");
MODULE_AUTHOR("Xiaotan Luo <lxt@rock-chips.com>");
MODULE_LICENSE("GPL v2");

原作者：KrisFei