分析声卡WM8960
- cd /proc/device-tree
- find * -iname i2s*
aliases/i2s __overrides__/i2s soc/gpio@7e200000/i2s soc/i2s@7e203000 __symbols__/i2s_pins __symbols__/i2s - soc/i2s@7e203000
- cat soc/i2s@7e203000/compatible
brcm,bcm2835-i2s - arch/arm/boot/dts/bcm283x.dtsi
/dts-v1/;
/plugin/;
/ {
compatible = "brcm,bcm2708";
fragment@0 {
target = <&i2s>;
__overlay__ {
status = "okay";
};
};
fragment@1 {
target-path="/";
__overlay__ {
wm8960_mclk: wm8960_mclk {
compatible = "fixed-clock";
#clock-cells = <0>;
clock-frequency = <12288000>;
};
};
};
fragment@2 {
target = <&i2c1>;
__overlay__ {
#address-cells = <1>;
#size-cells = <0>;
status = "okay";
wm8960: wm8960{
compatible = "wlf,wm8960";
reg = <0x1a>;
#sound-dai-cells = <0>;
AVDD-supply = <&vdd_5v0_reg>;
DVDD-supply = <&vdd_3v3_reg>;
};
};
};
fragment@3 {
target = <&sound>;
slave_overlay: __overlay__ {
compatible = "simple-audio-card";
simple-audio-card,format = "i2s";
simple-audio-card,name = "wm8960-soundcard";
status = "okay";
simple-audio-card,widgets =
"Microphone", "Mic Jack",
"Line", "Line In",
"Line", "Line Out",
"Speaker", "Speaker",
"Headphone", "Headphone Jack";
simple-audio-card,routing =
"Headphone Jack", "HP_L",
"Headphone Jack", "HP_R",
"Speaker", "SPK_LP",
"Speaker", "SPK_LN",
"LINPUT1", "Mic Jack",
"LINPUT3", "Mic Jack",
"RINPUT1", "Mic Jack",
"RINPUT2", "Mic Jack";
simple-audio-card,cpu {
sound-dai = <&i2s>;
};
dailink0_slave: simple-audio-card,codec {
sound-dai = <&wm8960>;
clocks = <&wm8960_mclk>;
clock-names = "mclk";
};
};
};
__overrides__ {
alsaname = <&slave_overlay>,"simple-audio-card,name";
compatible = <&wm8960>,"compatible";
master = <0>,"=2!3";
};
};
- CPU DAI:主控端的 Audio Data Interface，比如 I²S,Spdif,Pdm,Tdm
- CODEC DAI：即 Codec
- DAI_LINK:绑定 Cpu_Dai 和 Codec_Dai 为一个声卡，等同于 Machine Driver。
- DMAENGINE：用于 Cpu 和 I²S/Spdif 等 Dai 之间的 Dma 传输引擎，实际是通过Dma来进行数据的搬运。
- DAPM：动态音频电源管理，用于动态管理 Codec 等的电源管理，根据通路的开启配置开关，以达到保证功能的前提下功耗尽量小。
- JACK:耳机的接口检测，大部分使用 Codec 自身的检测机制，小部分使用 IO 来进行模拟。
- 一个声卡包含 cpu_dai, codec_dai, 以及 dai_link 组成，分别对应 cpu dai 的 dirver，比如 I²S driver, spdif driver；codec driver；dai_link driver，也就 是 machine driver，内核中支持两种方式创建声卡，一种是通用的 simple-card framework，一种是传统的编写自定义的 machine driver 来创建。
- Simple card 即简单通用的 machine driver， 如果 simple-card 框架足够满足需求，建议优先使用 simple card 框架，简单，方便，且易用。
- codec驱动：负责音频解码。这部分代码完全无平台无关，设备原厂提供，我们只需要把它加进内核编译就好了。
- platform驱动：与处理器芯片相关，这部分代码在该芯片商用之前方案产商提供的demo板已完全确定了，也就是说我们只需要使用就可以了。
- machine驱动：machine驱动是耦合platform和codec驱动，同时与上层交互的代码。由于上层是标准的alsa架构，所以下层接口肯定要做了统一，
@startsalt
* sound/soc/generic/simple-card.c
* module_platform_driver(asoc_simple_card);
* static struct platform_driver asoc_simple_card
* .of_match_table = asoc_simple_of_match,
* static const struct of_device_id asoc_simple_of_match[]
* { .compatible = "simple-audio-card", },
* .probe = asoc_simple_card_probe,
* ret = asoc_simple_card_parse_of(np, priv);
* ret = snd_soc_of_parse_audio_simple_widgets(&priv->snd_card, PREFIX "widgets");
* ret = snd_soc_of_parse_audio_routing(&priv->snd_card, PREFIX "routing");
* ret = asoc_simple_card_dai_link_of(node, priv, 0, true);
* snd_soc_card_set_drvdata(&priv->snd_card, priv);
* ret = devm_snd_soc_register_card(dev, card);
* ret = snd_soc_register_card(card);
* ret = soc_init_dai_link(card, link);
* ret = snd_soc_init_multicodec(card, link); // 初始化codec数据
* dai_link->num_codecs = 1;
* dai_link->codecs[0].name = dai_link->codec_name;
* dai_link->codecs[0].of_node = dai_link->codec_of_node;
* dai_link->codecs[0].dai_name = dai_link->codec_dai_name;
* ret = snd_soc_instantiate_card(card);
* ret = soc_bind_dai_link(card, dai_link);
* if (soc_is_dai_link_bound(card, dai_link)) // 如果已经绑定了就不用再绑定
* rtd = soc_new_pcm_runtime(card, dai_link);
* cpu_dai_component.name = dai_link->cpu_name;
* cpu_dai_component.of_node = dai_link->cpu_of_node; // 使用of_node进行匹配
* rtd->cpu_dai = snd_soc_find_dai(&cpu_dai_component); // 查找能够匹配的of_node匹配上的DAI，不是名字
* for_each_component(component)
* list_for_each_entry(component, &component_list, list)
* if (!snd_soc_is_matching_component(dlc, component))
* if (dlc->of_node && component_of_node != dlc->of_node) return 0; // of_node进行匹配
* if (dlc->name && strcmp(component->name, dlc->name)) return 0;
* snd_soc_rtdcom_add(rtd, rtd->cpu_dai->component); // esai dai
* snd_soc_rtdcom_add(rtd, codec_dais[i]->component); // codec dai
* snd_soc_rtdcom_add(rtd, component); // platform
* ret = soc_probe_link_components(card, rtd, order); // 调用component的probe函数
* ret = soc_probe_component(card, component);
* if (!strcmp(component->name, "snd-soc-dummy")) return 0;
* ret = component->driver->probe(component);
* ret = component->init(component);
* ret = soc_probe_link_dais(card, rtd, order);
* ret = soc_new_pcm(rtd, num); // <--------到这里创建出PCM
* ret = snd_pcm_new(rtd->card->snd_card, new_name, num, playback, capture, &pcm);
* return _snd_pcm_new(card, id, device, playback_count, capture_count, false, rpcm);
* static struct snd_device_ops ops = { .dev_free = snd_pcm_dev_free, .dev_register = snd_pcm_dev_register, .dev_disconnect = snd_pcm_dev_disconnect, };
* snd_pcm_dev_register // 这个回调函数会在声卡的注册阶段创建pcm设备节点/dev/snd/pcmCxxDxxp和/dev/snd/pcmCxxDxxc
* err = snd_pcm_add(pcm); // 将pcm加入到全局变量snd_pcm_devices，之后会创建/proc/asound/pcm文件
* err = snd_register_device(devtype, pcm->card, pcm->device, &snd_pcm_f_ops[cidx], pcm, &pcm->streams[cidx].dev);
* err = snd_pcm_new_stream(pcm, SNDRV_PCM_STREAM_PLAYBACK, playback_count);
* err = snd_pcm_new_stream(pcm, SNDRV_PCM_STREAM_CAPTURE, capture_count);
* err = snd_device_new(card, SNDRV_DEV_PCM, pcm, internal ? &internal_ops : &ops);
* ret = snd_card_register(card->snd_card);
@endsalt- http://www.waveshare.net/wiki/WM8960_Audio_HAT
- git clone https://github.com/waveshare/WM8960-Audio-HAT
- cd WM8960-Audio-HAT
- sudo ./install.sh
- sudo reboot
- sudo dkms status
- aplay -l
- arecord -l
- sudo arecord -f cd -Dhw:0 | aplay -Dhw:0
Recording WAVE 'stdin' : Signed 16 bit Little Endian, Rate 44100 Hz, Stereo Playing WAVE 'stdin' : Signed 16 bit Little Endian, Rate 44100 Hz, Stereo ^CAborted by signal Interrupt... Aborted by signal Interrupt... - sudo dkms remove -m wm8960-soundcard -v 0.1 --all
- find /lib/* -iname snd-soc-simple-card*
- sudo rmmod snd-soc-simple-card
- make
- sudo insmod snd-soc-wm8960-soundcard.ko
- sudo rmmod snd-soc-wm8960-soundcard.ko
#!/bin/bash
set -x
exec 1>/var/log/$(basename $0).log 2>&1
#enable i2c interface
dtparam i2c_arm=on
modprobe i2c-dev
sleep 1
# pi@raspberrypi:WM8960-Audio-HAT $ i2cdetect -y 1 0x1a 0x1a
# 0 1 2 3 4 5 6 7 8 9 a b c d e f
# 00:
# 10: UU
# 20:
# 30:
# 40:
# 50:
# 60:
# 70:
is_1a=$(i2cdetect -y 1 0x1a 0x1a | egrep "(1a|UU)" | awk '{print $2}')
if [ "x${is_1a}" != "x" ] ; then
echo "install wm8960-soundcard"
dtoverlay wm8960-soundcard
sleep 1
rm /etc/asound.conf
rm /var/lib/alsa/asound.state
echo "create wm8960-soundcard configure file"
ln -s /etc/wm8960-soundcard/asound.conf /etc/asound.conf
echo "create wm8960-soundcard status file"
ln -s /etc/wm8960-soundcard/wm8960_asound.state /var/lib/alsa/asound.state
fi
alsactl restore
#Fore 3.5mm ('headphone') jack
amixer cset numid=3 1