做面食专业网站,如何设计公司logo,吉安网站,东莞家用台灯东莞网站建设一、什么是ASOC
在嵌入式系统里面的声卡驱动为ASOC#xff08;ALSA System on Chip#xff09; #xff0c;它是在ALSA 驱动程序上封装的一层#xff0c;分为3大部分#xff0c;Machine#xff0c;Platform和Codec ,三部分的关系如下图所示#xff1a;其中Machine是指我…一、什么是ASOC
在嵌入式系统里面的声卡驱动为ASOCALSA System on Chip 它是在ALSA 驱动程序上封装的一层分为3大部分MachinePlatform和Codec ,三部分的关系如下图所示其中Machine是指我们的开发板Platform是指Soc,而Codec是指编解码器如uda1341 二、嵌入式系统声卡注册过程
这里我们以mini2440开发板为例
安装新驱动insmod alsa/driver/myalsa/platform/s3c2440_iis.ko
insmod alsa/driver/myalsa/platform/s3c2440_dma.ko
insmod alsa/driver/myalsa/codec/uda1341.ko
insmod alsa/driver/myalsa/machine/s3c2440_uda1341.ko
首先我们往内核安装我们写好的声卡驱动Machine部分的ko文件一定要放在最后面Platform和Codec 则无特殊要求下面会讲为什么
1.platform部分
1.1 cpu_dai 安装s3c2440_iis.ko的时候会注册平台驱动s3c24xx_iis_driver因为内核中有名字同为s3c24xx-iis的平台设备所以调用了对应的probe函数s3c24xx_iis_dev_probe该函数最终会把s3c24xx_i2s_daicpu_dai硬件操作相关放入链表dai_list并命名为s3c24xx-iis后面Machine驱动根据这个名字来实例化声卡
1. platform:
1.1 s3c24xx-i2s.c : 把s3c24xx_i2s_dai放入链表dai_list, .name s3c24xx-iis,
s3c24xx_iis_dev_probesnd_soc_register_dai(pdev-dev, s3c24xx_i2s_dai);list_add(dai-list, dai_list);
平台驱动
static struct platform_driver s3c24xx_iis_driver {.probe s3c24xx_iis_dev_probe,.remove s3c24xx_iis_dev_remove,.driver {.name s3c24xx-iis,.owner THIS_MODULE,},
};平台设备
struct platform_device s3c_device_iis {.name s3c24xx-iis,.id -1,.num_resources ARRAY_SIZE(s3c_iis_resource),.resource s3c_iis_resource,.dev {.dma_mask s3c_device_iis_dmamask,.coherent_dma_mask 0xffffffffUL}
};
static struct snd_soc_dai_ops s3c24xx_i2s_dai_ops {.trigger s3c24xx_i2s_trigger,.hw_params s3c24xx_i2s_hw_params,.set_fmt s3c24xx_i2s_set_fmt,.set_clkdiv s3c24xx_i2s_set_clkdiv,.set_sysclk s3c24xx_i2s_set_sysclk,
};//cpu_dai相关的硬件操作
static struct snd_soc_dai_driver s3c24xx_i2s_dai {.probe s3c24xx_i2s_probe,.suspend s3c24xx_i2s_suspend,.resume s3c24xx_i2s_resume,.playback {.channels_min 2,.channels_max 2,.rates S3C24XX_I2S_RATES,.formats SNDRV_PCM_FMTBIT_S8 | SNDRV_PCM_FMTBIT_S16_LE,},.capture {.channels_min 2,.channels_max 2,.rates S3C24XX_I2S_RATES,.formats SNDRV_PCM_FMTBIT_S8 | SNDRV_PCM_FMTBIT_S16_LE,},.ops s3c24xx_i2s_dai_ops,
};
1.2 platform_dma
安装s3c2440_dma.ko时把samsung_asoc_platform放入了链表platform_list并命名为samsung-audio后面Machineko驱动根据这个名字来实例化声卡
1.2 sound/soc/samsung/dma.c : 把samsung_asoc_platform放入了链表platform_list, .name samsung-audio,
samsung_asoc_platform_probesnd_soc_register_platform(pdev-dev, samsung_asoc_platform);list_add(platform-list, platform_list);
static struct snd_pcm_ops dma_ops {.open dma_open,.close dma_close,.ioctl snd_pcm_lib_ioctl,.hw_params dma_hw_params,.hw_free dma_hw_free,.prepare dma_prepare,.trigger dma_trigger,.pointer dma_pointer,.mmap dma_mmap,
};
//cpu_dam相关的硬件操作
static struct snd_soc_platform_driver samsung_asoc_platform {.ops dma_ops,.pcm_new dma_new,.pcm_free dma_free_dma_buffers,
};
2. codec注册部分
安装uda1341.ko 时把soc_codec_dev_uda134x和uda134x_dai分别放入dai_list和codec_list链表用于后面的Machineko驱动实例化声卡
2. codec: uda134x.c
uda134x_codec_probesnd_soc_register_codec(pdev-dev,soc_codec_dev_uda134x, uda134x_dai, 1);struct snd_soc_codec *codec;codec-driver codec_drv; soc_codec_dev_uda134xsnd_soc_register_dais(dev, dai_drv, num_dai); // uda134x_dailist_add(dai-list, dai_list); : 把uda134x_dai放入了链表dai_listlist_add(codec-list, codec_list); 把soc_codec_dev_uda134x放入了链表codec_list
//设置codec芯片的硬件操作
static struct snd_soc_codec_driver soc_codec_dev_uda134x {.probe uda134x_soc_probe,.remove uda134x_soc_remove,.suspend uda134x_soc_suspend,.resume uda134x_soc_resume,.reg_cache_size sizeof(uda134x_reg),.reg_word_size sizeof(u8),.reg_cache_default uda134x_reg,.reg_cache_step 1,.read uda134x_read_reg_cache,.write uda134x_write,.set_bias_level uda134x_set_bias_level,
}; static struct snd_soc_dai_ops uda134x_dai_ops {.startup uda134x_startup,.shutdown uda134x_shutdown,.hw_params uda134x_hw_params,.digital_mute uda134x_mute,.set_sysclk uda134x_set_dai_sysclk,.set_fmt uda134x_set_dai_fmt,
};//codec_dai相关的硬件操作
static struct snd_soc_dai_driver uda134x_dai {.name uda134x-hifi,/* playback capabilities */.playback {.stream_name Playback,.channels_min 1,.channels_max 2,.rates UDA134X_RATES,.formats UDA134X_FORMATS,},/* capture capabilities */.capture {.stream_name Capture,.channels_min 1,.channels_max 2,.rates UDA134X_RATES,.formats UDA134X_FORMATS,},/* pcm operations */.ops uda134x_dai_ops,
};
3. machine部分
machine部分内容很多总的调用过程如下
s3c24xx_uda134x_probes3c24xx_uda134x_snd_device platform_device_alloc(soc-audio, -1);platform_set_drvdata(s3c24xx_uda134x_snd_device, snd_soc_s3c24xx_uda134x); platform_device_add(s3c24xx_uda134x_snd_device);.....soc_probesnd_soc_register_card(card); // card snd_soc_s3c24xx_uda134xcard-rtd devm_kzalloc(card-dev,...card-rtd[i].dai_link card-dai_link[i]; // s3c24xx_uda134x_dai_linklist_add(card-list, card_list);snd_soc_instantiate_cards(); // 实例化声卡snd_soc_instantiate_card(card);3.1 /* bind DAIs */for (i 0; i card-num_links; i)soc_bind_dai_link(card, i);3.1.1 /* find CPU DAI */rtd-cpu_dai cpu_dai; //s3c24xx_i2s_dai3.1.2 /* find_codec */rtd-codec codec; // codec, codec-driversoc_codec_dev_uda134x3.1.3 /* find CODEC DAI */ rtd-codec_dai codec_dai; // uda134x_dai3.1.4 /* find_platform */rtd-platform platform; // samsung_asoc_platform3.2 /* initialize the register cache for each available codec */ret snd_soc_init_codec_cache(codec, compress_type);3.3 snd_card_createerr snd_ctl_create(card);static struct snd_device_ops ops {.dev_free snd_ctl_dev_free,.dev_register snd_ctl_dev_register,.dev_disconnect snd_ctl_dev_disconnect,};snd_device_new(card, SNDRV_DEV_CONTROL, card, ops);dev-ops ops;3.4 /* early DAI link probe */soc_probe_dai_link /* probe the cpu_dai *//* probe the CODEC *//* probe the platform *//* probe the CODEC DAI *//* create the pcm */ret soc_new_pcm(rtd, num);struct snd_pcm_ops *soc_pcm_ops rtd-ops;soc_pcm_ops-open soc_pcm_open;soc_pcm_ops-close soc_pcm_close;soc_pcm_ops-hw_params soc_pcm_hw_params;soc_pcm_ops-hw_free soc_pcm_hw_free;soc_pcm_ops-prepare soc_pcm_prepare;soc_pcm_ops-trigger soc_pcm_trigger;soc_pcm_ops-pointer soc_pcm_pointer;snd_pcm_newstatic struct snd_device_ops ops {.dev_free snd_pcm_dev_free,.dev_register snd_pcm_dev_register,.dev_disconnect snd_pcm_dev_disconnect,};err snd_device_new(card, SNDRV_DEV_PCM, pcm, ops)dev-ops ops;pcm-private_data rtd;3.5 snd_card_registersnd_device_register_allerr dev-ops-dev_register(dev)调用前面snd_pcm_new的snd_pcm_dev_registersnd_pcm_dev_registererr snd_register_device_for_dev(devtype, pcm-card,pcm-device,snd_pcm_f_ops[cidx],pcm, str, dev);
安装s3c2440_uda1341.ko时注册平台驱动s3c24xx_uda134x_driver因为内核中有同名的平台设备mini2440_audio所以调用了s3c24xx_uda134x_probe函数
//平台驱动
static struct platform_driver s3c24xx_uda134x_driver {.probe s3c24xx_uda134x_probe,.remove s3c24xx_uda134x_remove,.driver {.name s3c24xx_uda134x,.owner THIS_MODULE,},
};//平台设备
static struct platform_device mini2440_audio {.name s3c24xx_uda134x,.id 0,.dev {.platform_data mini2440_audio_pins,},
};
①s3c24xx_uda134x_probe函数调用platform_set_drvdata把snd_soc_card结构体snd_soc_s3c24xx_uda134x含有dai_link用来负责连接Platform 和Codec实例化的时候会用到保存在pdevplatform_device-dev-p-driver_data中然后platform_device_add(s3c24xx_uda134x_snd_device)因为内核中有同名的平台驱动soc_driver所以调用该驱动的probe函数(soc_probe函数) s3c24xx_uda134x_snd_device platform_device_alloc(soc-audio, -1);platform_set_drvdata(s3c24xx_uda134x_snd_device, snd_soc_s3c24xx_uda134x); dev_set_drvdata(pdev-dev, data);dev-p-driver_data data; platform_device_add(s3c24xx_uda134x_snd_device);
//指定了platform和codec
static struct snd_soc_dai_link s3c24xx_uda134x_dai_link {.name UDA134X,.stream_name UDA134X,.codec_name uda134x-codec,.codec_dai_name uda134x-hifi,.cpu_dai_name s3c24xx-iis,.ops s3c24xx_uda134x_ops,.platform_name samsung-audio,
};static struct snd_soc_card snd_soc_s3c24xx_uda134x {.name S3C24XX_UDA134X,.dai_link s3c24xx_uda134x_dai_link,.num_links 1, //只有1个dai_link
};
/* ASoC platform driver */
static struct platform_driver soc_driver {.driver {.name soc-audio,.owner THIS_MODULE,.pm snd_soc_pm_ops,},.probe soc_probe,.remove soc_remove,
};
②soc_probe函数调用platform_get_drvdata函数把第①步的snd_soc_card结构体snd_soc_s3c24xx_uda134x含有dai_link用来负责连接Platform和Codec实例化的时候会用到取出来然后调用snd_soc_register_card函数注册它。
soc_probestruct snd_soc_card *card platform_get_drvdata(pdev);return dev-p-driver_data;snd_soc_register_card(card); // card snd_soc_s3c24xx_uda134x
③snd_soc_register_card函数取出snd_soc_card结构体的dai_linksnd_soc_s3c24xx_uda134x结构体只有一个dai_link这里的for只执行一次然后调用snd_soc_instantiate_cards函数实例化声卡其实就是根据snd_soc_s3c24xx_uda134x结构体里面的dai_link指定的名字在dai_list、platform_list、codec_list链表找到我们之前platform和codec注册部分放入队列的那四个结构体。soc_bind_dai_link函数逐个扫描这三个链表根据card-dai_link[]中的名称进行匹配匹配后把相应的codecdai和platform实例赋值到snd_soc_cardcard-rtd[]中snd_soc_pcm_runtime。经过这个过程后snd_soc_pcm_runtimecard-rtd中保存了本Machine中使用的CodecDAI和Platform驱动的信息
snd_soc_register_cardcard-rtd kzalloc(sizeof(struct snd_soc_pcm_runtime) *(card-num_links card-num_aux_devs),GFP_KERNEL);for (i 0; i card-num_links; i)card-rtd[i].dai_link card-dai_link[i];list_add(card-list, card_list);snd_soc_instantiate_cards();snd_soc_instantiate_card(card);soc_bind_dai_link(card, i);/* find CPU DAI */rtd-cpu_dai cpu_dai; //s3c24xx_i2s_dai/* find_codec */rtd-codec codec; // codec, codec-driversoc_codec_dev_uda134x/* find CODEC DAI */ rtd-codec_dai codec_dai; // uda134x_dai/* find_platform */rtd-platform platform; // samsung_asoc_platform
④调用传统ALSA声卡驱动的APIsnd_card_create函数该函数再调用snd_ctl_createsnd_ctl_create函数调用snd_device_new把snd_device_ops结构体ops填充到snd_device的ops成员dev-ops ops;然后把snd_device挂到snd_cardcard-devices链表中。后面第⑧步snd_card_register的时候会用到snd_device_ops结构体的dev_register成员。目前我们只是先把它挂在一个链表中如下图 3.3 snd_card_createerr snd_ctl_create(card);static struct snd_device_ops ops {.dev_free snd_ctl_dev_free,.dev_register snd_ctl_dev_register,.dev_disconnect snd_ctl_dev_disconnect,};snd_device_new(card, SNDRV_DEV_CONTROL, card, ops);dev-ops ops; ⑤soc_probe_dai_link函数先是调用前面第三步找出来的cpu_dai等的probe函数例如s3c24xx_i2s_dai结构体的s3c24xx_iis_dev_probe说白了就是硬件初始化。然后调用soc_new_pcm。
soc_probe_dai_link /* probe the cpu_dai */ret cpu_dai-driver-probe(cpu_dai);/* probe the CODEC */ret soc_probe_codec(card, codec);/* probe the platform */ret platform-driver-probe(platform);/* probe the CODEC DAI */ret codec_dai-driver-probe(codec_dai);/* create the pcm */ret soc_new_pcm(rtd, num);
⑥soc_new_pcm函数函数先是给card-rtd-ops结构体里的函数指针赋值APP调用的程序的过程中会通过这些函数再去调用到硬件相关的函数如前面platform的s3c24xx_i2s_dai然后把card-rtd-ops的地址赋给substream-ops。最后调用snd_pcm_new。
ret soc_new_pcm(rtd, num);struct snd_pcm_ops *soc_pcm_ops rtd-ops;soc_pcm_ops-open soc_pcm_open;soc_pcm_ops-close soc_pcm_close;soc_pcm_ops-hw_params soc_pcm_hw_params;soc_pcm_ops-hw_free soc_pcm_hw_free;soc_pcm_ops-prepare soc_pcm_prepare;soc_pcm_ops-trigger soc_pcm_trigger;soc_pcm_ops-pointer soc_pcm_pointer;snd_pcm_newsnd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK, soc_pcm_ops);substream-ops ops;
或snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_CAPTURE, soc_pcm_ops);substream-ops ops;
⑦snd_pcm_new是传统的ALSA声卡驱动API这一步和第④步是相似的区别在于第④步对应的是snd_control这里是snd_pcm的。snd_pcm_new执行完又回到soc_new_pcm函数的这里有一个(snd_pcm)pcm-private_data rtd;后面我们APP调用程序的时候会从pcm-private_data取出rtdrtd里有对应我们开发板的cpu_dai、codec_dai...
snd_pcm_newstatic struct snd_device_ops ops {.dev_free snd_pcm_dev_free,.dev_register snd_pcm_dev_register,.dev_disconnect snd_pcm_dev_disconnect,};err snd_device_new(card, SNDRV_DEV_PCM, pcm, ops)dev-ops ops;pcm-private_data rtd;
⑧snd_card_register该函数会调用前面第④、⑦步的snd_ctl_dev_register和snd_pcm_dev_register通过snd_device_register_all()注册所有挂在该声卡下的逻辑设备snd_device_register_all()实际上是通过snd_card的devices链表遍历所有的snd_device并且调用snd_device的ops-dev_register()来实现各自设备的注册的这两个函数也是传统的ALSA声卡的API它们最后都会调用到snd_register_device_for_dev函数将snd_ctl_f_ops、snd_pcm_f_ops作为snd_register_device_for_dev的参数被传入并被记录在snd_minors[minor]中的字段f_ops中并创建设备节点device_createclass_create则是在sound_core.c中。用户程序需要打开control、pcm设备时驱动程序通过snd_minors[]全局数组和此设备号可以获得snd_ctl_f_ops、snd_pcm_f_ops结构中的各个回调函数在另外一篇文章里介绍
3.5 snd_card_registersnd_device_register_allerr dev-ops-dev_register(dev)调用前面snd_ctl_create的snd_ctl_dev_register和snd_pcm_new的snd_pcm_dev_registersnd_ctl_dev_registersnd_register_device(SNDRV_DEVICE_TYPE_CONTROL, card, -1,snd_ctl_f_ops, card, name)snd_register_device_for_devpreg-type type;preg-card card ? card-number : -1;preg-device dev;preg-f_ops f_ops;preg-private_data private_data;snd_minors[minor] preg;preg-dev device_create(sound_class, device, MKDEV(major, minor),private_data, %s, name);和snd_pcm_dev_registererr snd_register_device_for_dev(devtype, pcm-card,pcm-device,snd_pcm_f_ops[cidx],pcm, str, dev);
static const struct file_operations snd_ctl_f_ops
{.owner THIS_MODULE,.read snd_ctl_read,.open snd_ctl_open,.release snd_ctl_release,.llseek no_llseek,.poll snd_ctl_poll,.unlocked_ioctl snd_ctl_ioctl,.compat_ioctl snd_ctl_ioctl_compat,.fasync snd_ctl_fasync,
};const struct file_operations snd_pcm_f_ops[2] {{.owner THIS_MODULE,.write snd_pcm_write,.aio_write snd_pcm_aio_write,.open snd_pcm_playback_open,.release snd_pcm_release,.llseek no_llseek,.poll snd_pcm_playback_poll,.unlocked_ioctl snd_pcm_playback_ioctl,.compat_ioctl snd_pcm_ioctl_compat,.mmap snd_pcm_mmap,.fasync snd_pcm_fasync,.get_unmapped_area snd_pcm_get_unmapped_area,},{.owner THIS_MODULE,.read snd_pcm_read,.aio_read snd_pcm_aio_read,.open snd_pcm_capture_open,.release snd_pcm_release,.llseek no_llseek,.poll snd_pcm_capture_poll,.unlocked_ioctl snd_pcm_capture_ioctl,.compat_ioctl snd_pcm_ioctl_compat,.mmap snd_pcm_mmap,.fasync snd_pcm_fasync,.get_unmapped_area snd_pcm_get_unmapped_area,}
};至此machine部分的任务已经完成。 4. 字符设备注册
在sound/core/sound.c中有alsa_sound_init()函数register_chrdev中的参数major与之前创建pcm设备是device_create时的major是同一个这样的结果是当应用程序open设备文件/dev/snd/pcmCxDxp时会进入snd_fops的open回调函数该open函数以次设备号为索引从snd_minors全局数组中取出当初注册conrol、pcm设备时填充的snd_minor结构然后从snd_minor结构中取出control、pcm设备的f_ops并且把file-f_op替换为pcm设备的f_ops紧接着直接调用pcm设备的f_ops-open()...
#define CONFIG_SND_MAJOR 116 /* standard configuration */
static int major CONFIG_SND_MAJOR;static const struct file_operations snd_fops
{.owner THIS_MODULE,.open snd_open,.llseek noop_llseek,
};alsa_sound_initregister_chrdev(major, alsa, snd_fops)
调用过程我们在下一篇文章再来详细介绍。
