四、MACHINE（simple-card.c）驱动分析

1、MACHINE相关的重要数据

struct snd_soc_dai_link {/* config - must be set by machine driver */const char *name;         /* Codec name */const char *stream_name;        /* Stream name *//** You MAY specify the link's CPU-side device, either by device name,* or by DT/OF node, but not both. If this information is omitted,* the CPU-side DAI is matched using .cpu_dai_name only, which hence* must be globally unique. These fields are currently typically used* only for codec to codec links, or systems using device tree.*/const char *cpu_name;struct device_node *cpu_of_node;/** You MAY specify the DAI name of the CPU DAI. If this information is* omitted, the CPU-side DAI is matched using .cpu_name/.cpu_of_node* only, which only works well when that device exposes a single DAI.*/const char *cpu_dai_name;/** You MUST specify the link's codec, either by device name, or by* DT/OF node, but not both.*/const char *codec_name;struct device_node *codec_of_node;/* You MUST specify the DAI name within the codec */const char *codec_dai_name;struct snd_soc_dai_link_component *codecs;unsigned int num_codecs;/** You MAY specify the link's platform/PCM/DMA driver, either by* device name, or by DT/OF node, but not both. Some forms of link* do not need a platform.*/const char *platform_name;struct device_node *platform_of_node;int id;   /* optional ID for machine driver link identification */const struct snd_soc_pcm_stream *params;unsigned int num_params;unsigned int dai_fmt;           /* format to set on init */enum snd_soc_dpcm_trigger trigger[2]; /* trigger type for DPCM *//* codec/machine specific init - e.g. add machine controls */int (*init)(struct snd_soc_pcm_runtime *rtd);/* optional hw_params re-writing for BE and FE sync */int (*be_hw_params_fixup)(struct snd_soc_pcm_runtime *rtd,struct snd_pcm_hw_params *params);/* machine stream operations */const struct snd_soc_ops *ops;const struct snd_soc_compr_ops *compr_ops;/* Mark this pcm with non atomic ops */bool nonatomic;/* For unidirectional dai links */unsigned int playback_only:1;unsigned int capture_only:1;/* Keep DAI active over suspend */unsigned int ignore_suspend:1;/* Symmetry requirements */unsigned int symmetric_rates:1;unsigned int symmetric_channels:1;unsigned int symmetric_samplebits:1;/* Do not create a PCM for this DAI link (Backend link) */unsigned int no_pcm:1;/* This DAI link can route to other DAI links at runtime (Frontend)*/unsigned int dynamic:1;/* This DAI link can be reconfigured at runtime (Backend) */unsigned int dynamic_be:1;/** This DAI can support no host IO (no pcm data is* copied to from host)*/unsigned int no_host_mode:2;/* DPCM capture and Playback support */unsigned int dpcm_capture:1;unsigned int dpcm_playback:1;/* DPCM used FE & BE merged format */unsigned int dpcm_merged_format:1;/* DPCM used FE & BE merged channel */unsigned int dpcm_merged_chan:1;/* DPCM used FE & BE merged rate */unsigned int dpcm_merged_rate:1;/* pmdown_time is ignored at stop */unsigned int ignore_pmdown_time:1;/* Do not create a PCM for this DAI link (Backend link) */unsigned int ignore:1;struct list_head list; /* DAI link list of the soc card */struct snd_soc_dobj dobj; /* For topology *//* this value determines what all ops can be started asynchronously */enum snd_soc_async_ops async_ops;
};

struct snd_soc_card {const char *name;const char *long_name;const char *driver_name;char dmi_longname[80];char topology_shortname[32];struct device *dev;struct snd_card *snd_card;struct module *owner;struct mutex mutex;struct mutex dapm_mutex;struct mutex dapm_power_mutex;bool instantiated;bool topology_shortname_created;int (*probe)(struct snd_soc_card *card);int (*late_probe)(struct snd_soc_card *card);int (*remove)(struct snd_soc_card *card);/* the pre and post PM functions are used to do any PM work before and* after the codec and DAI's do any PM work. */int (*suspend_pre)(struct snd_soc_card *card);int (*suspend_post)(struct snd_soc_card *card);int (*resume_pre)(struct snd_soc_card *card);int (*resume_post)(struct snd_soc_card *card);/* callbacks */int (*set_bias_level)(struct snd_soc_card *,struct snd_soc_dapm_context *dapm,enum snd_soc_bias_level level);int (*set_bias_level_post)(struct snd_soc_card *,struct snd_soc_dapm_context *dapm,enum snd_soc_bias_level level);int (*add_dai_link)(struct snd_soc_card *,struct snd_soc_dai_link *link);void (*remove_dai_link)(struct snd_soc_card *,struct snd_soc_dai_link *link);long pmdown_time;/* CPU <--> Codec DAI links  */struct snd_soc_dai_link *dai_link;  /* predefined links only */int num_links;  /* predefined links only */struct list_head dai_link_list; /* all links */int num_dai_links;struct list_head rtd_list;int num_rtd;/* optional codec specific configuration */struct snd_soc_codec_conf *codec_conf;int num_configs;/** optional auxiliary devices such as amplifiers or codecs with DAI* link unused*/struct snd_soc_aux_dev *aux_dev;int num_aux_devs;struct list_head aux_comp_list;const struct snd_kcontrol_new *controls;int num_controls;/** Card-specific routes and widgets.* Note: of_dapm_xxx for Device Tree; Otherwise for driver build-in.*/const struct snd_soc_dapm_widget *dapm_widgets;int num_dapm_widgets;const struct snd_soc_dapm_route *dapm_routes;int num_dapm_routes;const struct snd_soc_dapm_widget *of_dapm_widgets;int num_of_dapm_widgets;const struct snd_soc_dapm_route *of_dapm_routes;int num_of_dapm_routes;bool fully_routed;struct work_struct deferred_resume_work;/* lists of probed devices belonging to this card */struct list_head component_dev_list;struct list_head widgets;struct list_head paths;struct list_head dapm_list;struct list_head dapm_dirty;/* attached dynamic objects */struct list_head dobj_list;/* Generic DAPM context for the card */struct snd_soc_dapm_context dapm;struct snd_soc_dapm_stats dapm_stats;struct snd_soc_dapm_update *update;#ifdef CONFIG_DEBUG_FSstruct dentry *debugfs_card_root;struct dentry *debugfs_pop_time;
#endifu32 pop_time;void *drvdata;
};

    rk809_sound: rk809-sound {status = "okay";compatible = "simple-audio-card";simple-audio-card,format = "i2s";simple-audio-card,name = "rockchip,rk809-codec";simple-audio-card,mclk-fs = <256>;simple-audio-card,widgets ="Microphone", "Mic Jack","Headphone", "Headphone Jack";simple-audio-card,routing ="Mic Jack", "MICBIAS1","IN1P", "Mic Jack","Headphone Jack", "HPOL","Headphone Jack", "HPOR";simple-audio-card,cpu {sound-dai = <&i2s1_8ch>;};simple-audio-card,codec {sound-dai = <&rk809_codec>;};};

static int asoc_simple_card_probe(struct platform_device *pdev)
{struct snd_soc_dai_link *dai_link;struct snd_soc_card *card;...//初始化snd_soc_cardcard = simple_priv_to_card(priv);card->owner       = THIS_MODULE;card->dev     = dev;card->dai_link        = priv->dai_link;card->num_links     = num;card->probe       = asoc_simple_soc_card_probe;//从DTS中获取cpu_dai\codec_dai节点、widgets、routing等信息，填充snd_soc_dai_linkasoc_simple_card_parse_of(priv);->asoc_simple_card_of_parse_widgets(card, PREFIX); asoc_simple_card_of_parse_routing(card, PREFIX, 1);asoc_simple_card_dai_link_of(node, priv, 0, true);//实例化和填充card，绑定dailink，创建音频节点pcmC0D0P，并完成cpu_dai和codec的probe devm_snd_soc_register_card(dev, card);snd_soc_register_card(card);->snd_soc_instantiate_card(card); ...
}

    devm_snd_soc_register_card(dev, card);snd_soc_register_card(card);->snd_soc_instantiate_card(card); ->soc_bind_dai_link(card, &card->dai_link[i]);snd_card_new(card->dev, SNDRV_DEFAULT_IDX1, SNDRV_DEFAULT_STR1,card->owner, 0, &card->snd_card); //绑定完成后申请一个声卡card->probe(card); //仅初始化一次声卡soc_probe_link_components(card, rtd, order); //probe 该声卡dai_link上的所有components组件soc_probe_link_dais(card, rtd, order); //probe 该声卡所有dai_link->//建立playback stream/capture stream，相应的substream也同时建立,ops绑定snd_pcm_dev_register，回调函数会在声卡的 注册阶段被调用soc_new_pcm(rtd, num); // 设置操作该pcm的控制/操作接口函数snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK, &rtd->ops);snd_card_register(card->snd_card);   //注册声卡，遍历声卡下的所有逻辑设备，调用各设备的注册回调函数，对于pcm，就是上面提到的snd_pcm_dev_register函数，该回调函数建立了和用户空间应用程序（alsa-lib）通信所用的设备文件节点:/dev/snd/pcmCxxDxxp 和 /dev/snd/pcmCxxDxxc

const struct file_operations snd_pcm_f_ops[2] = {{.owner =       THIS_MODULE,.write =       snd_pcm_write,.write_iter =        snd_pcm_writev,.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,.read_iter =      snd_pcm_readv,.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,}
};

int soc_new_pcm(struct snd_soc_pcm_runtime *rtd, int num)
{.../* ASoC PCM operations */if (rtd->dai_link->dynamic) {rtd->ops.open        = dpcm_fe_dai_open;rtd->ops.hw_params   = dpcm_fe_dai_hw_params;rtd->ops.prepare    = dpcm_fe_dai_prepare;rtd->ops.trigger  = dpcm_fe_dai_trigger;rtd->ops.hw_free  = dpcm_fe_dai_hw_free;rtd->ops.close        = dpcm_fe_dai_close;rtd->ops.pointer    = soc_pcm_pointer;rtd->ops.ioctl        = soc_pcm_ioctl;} else {rtd->ops.open       = soc_pcm_open;rtd->ops.hw_params   = soc_pcm_hw_params;rtd->ops.prepare    = soc_pcm_prepare;rtd->ops.trigger  = soc_pcm_trigger;rtd->ops.hw_free  = soc_pcm_hw_free;rtd->ops.close        = soc_pcm_close;rtd->ops.pointer    = soc_pcm_pointer;rtd->ops.ioctl        = soc_pcm_ioctl;}...if (playback)snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK, &rtd->ops);if (capture)snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_CAPTURE, &rtd->ops);...
}