结构体介绍
先介绍声卡相关结构体
struct asoc_simple_priv {
struct snd_soc_card snd_card;
struct simple_dai_props {
struct asoc_simple_dai *cpu_dai;
struct asoc_simple_dai *codec_dai;
struct snd_soc_dai_link_component cpus; /* single cpu */
struct snd_soc_dai_link_component codecs; /* single codec */
struct snd_soc_dai_link_component platforms;
struct asoc_simple_data adata;
struct snd_soc_codec_conf *codec_conf;
bool mclk_fp;
unsigned int mclk_fs;
unsigned int cpu_pll_fs;
unsigned int codec_pll_fs;
} *dai_props;
struct asoc_simple_jack hp_jack;
struct asoc_simple_jack mic_jack;
struct snd_soc_dai_link *dai_link;
struct asoc_simple_dai *dais;
struct snd_soc_codec_conf *codec_conf;
struct gpio_desc *pa_gpio;
};
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;
/* Mutex for PCM operations */
struct mutex pcm_mutex;
enum snd_soc_pcm_subclass pcm_subclass;
spinlock_t dpcm_lock;
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 */
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;
bool disable_route_checks;
/* lists of probed devices belonging to this card */
struct list_head component_dev_list;
struct list_head 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_FS
struct dentry *debugfs_card_root;
#endif
#ifdef CONFIG_PM_SLEEP
struct work_struct deferred_resume_work;
#endif
u32 pop_time;
void *drvdata;
ANDROID_KABI_RESERVE(1);
ANDROID_KABI_RESERVE(2);
ANDROID_KABI_RESERVE(3);
ANDROID_KABI_RESERVE(4);
};
struct snd_card {
int number; /* number of soundcard (index to
snd_cards) */
char id[16]; /* id string of this card */
char driver[16]; /* driver name */
char shortname[32]; /* short name of this soundcard */
char longname[80]; /* name of this soundcard */
char irq_descr[32]; /* Interrupt description */
char mixername[80]; /* mixer name */
char components[128]; /* card components delimited with
space */
struct module *module; /* top-level module */
void *private_data; /* private data for soundcard */
void (*private_free) (struct snd_card *card); /* callback for freeing of
private data */
struct list_head devices; /* devices */
struct device ctl_dev; /* control device */
unsigned int last_numid; /* last used numeric ID */
struct rw_semaphore controls_rwsem; /* controls list lock */
rwlock_t ctl_files_rwlock; /* ctl_files list lock */
int controls_count; /* count of all controls */
int user_ctl_count; /* count of all user controls */
struct list_head controls; /* all controls for this card */
struct list_head ctl_files; /* active control files */
struct snd_info_entry *proc_root; /* root for soundcard specific files */
struct proc_dir_entry *proc_root_link; /* number link to real id */
struct list_head files_list; /* all files associated to this card */
struct snd_shutdown_f_ops *s_f_ops; /* file operations in the shutdown
state */
spinlock_t files_lock; /* lock the files for this card */
int shutdown; /* this card is going down */
struct completion *release_completion;
struct device *dev; /* device assigned to this card */
struct device card_dev; /* cardX object for sysfs */
const struct attribute_group *dev_groups[4]; /* assigned sysfs attr */
bool registered; /* card_dev is registered? */
wait_queue_head_t remove_sleep;
#ifdef CONFIG_PM
unsigned int power_state; /* power state */
wait_queue_head_t power_sleep;
#endif
#if IS_ENABLED(CONFIG_SND_MIXER_OSS)
struct snd_mixer_oss *mixer_oss;
int mixer_oss_change_count;
#endif
ANDROID_KABI_RESERVE(1);
ANDROID_KABI_RESERVE(2);
};可以看出，三个结构体的大致内容：
asoc_simple_priv:
-
属于该结构体的snd_soc_card
-
dai相关
-
时钟相关
-
耳机、麦克风拔插相关
-
功放相关
snd_soc_card:
-
snd_soc_card的基本信息
-
属于该结构体的snd_card
-
各种mutex(PCM、DAPM等)
-
电源管理相关的操作函数
-
回调函数(DAPM、DAI LINK)
-
DAPM、DAI LINK相关
snd_card:
-
声卡的基本信息
-
属于该声卡的control设备
-
proc文件系统的相关配置
-
sys文件系统的相关配置
流程介绍
probe()
-
为asoc_simple_priv分配空间并初始化 --- devm_kzalloc_priv() asoc_simple_init_priv()
-
判断pdev->dev的status是否为okay --- of_device_is_available()
-
最后跳到进行声卡注册 --- devm_snd_soc_register_card()
3.1 snd_soc_register_card() --- 初始化card里的内核链表以及mutex，
3.1.1 然后return snd_soc_bind_card()
snd_soc_bind_card()
-
实例化snd_soc_card --- snd_soc_instantiate_card()
snd_soc_instantiate_card()
-
初始化snd_soc_dai_link结构体（关于dai匹配）--- soc_init_dai_link()
-
初始化dapm，并把dapm->list加到card->dapm_list里面 --- snd_soc_dapm_init()
-
绑定dai link--- soc_bind_dai_link()
3.1 soc_new_pcm_runtime() --- 初始化rtd（该结构体与绑定codec和platform有关）
3.2 通过snd_soc_find_dai() 和 snd_soc_rtdcom_add()来拿到已经注册的codec和platform并添加到rtd
3.3 通过soc_add_pcm_runtime()将rtd添加到card -
绑定aux设备（耳机口），也是从component list中找到再给card --- soc_bind_aux_dev()
-
都完成都开始创建声卡 --- snd_card_new()
-
初始化dubugfs --- soc_init_card_debugfs()
-
初始化dapm部分 --- snd_soc_dapm_new_controls()
-
初始化声卡（仅一次）--- card->probe
-
初始化所有dai用到的component --- soc_probe_link_components()
-
初始化所有aux设备 --- soc_probe_aux_devices()
-
初始化dai links的时候可能会添加新的dais和dai links，所以还需要再进行一次1和3
-
初始化所有的dai link --- soc_probe_link_dais()
-
创建、添加PCM设备 --- soc_link_init()
-
连接dapm --- snd_soc_dapm_link_dai_widgets() snd_soc_dapm_connect_dai_link_widgets()
-
注册control设备 --- snd_soc_add_card_controls()
-
注册dapm的route --- snd_soc_dapm_add_routes()
-
注册设备树的dapm的route --- snd_soc_dapm_add_routes()
-
尝试设置dmi_name --- snd_soc_set_dmi_name()
-
设置snd_card->name --- snprintf(card->snd_card->**name, ...)
-
执行后部分初始化 --- card->late_probe()
-
注册dapm_widget --- snd_soc_dapm_new_widgets()
-
注册声卡 --- snd_card_register(card->snd_card)
-
检查所有dapm尾指针 --- dapm_mark_endpoints_dirty() snd_soc_dapm_sync()
snd_card_register()
-
注册声卡设备 --- device_add(&card->card_dev)
-
注册所属声卡的所有设备 --- snd_device_register_all()
-
通过 if 判断声卡是否已经注册 --- snd_cards[card->num]
-
设置card->id --- snd_card_set_id_no_lock()
-
加入到snd_cards[ ]中 --- snd_card[card->num] = card
-
注册card的proc文件--- snd_info_card_register()