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< div class = " wh_topic_content body " > < main role = "main" > < article class = "- topic/topic concept/concept topic concept" role = "article" aria-labelledby = "ariaid-title1" > < span class = "edit-link" style = "font-size:12px; opacity:0.6; text-align:right; vertical-align:middle" > < a target = "_blank" href = "http://172.16.35.88/tasks/jdssno1uvvbf2mltu9kb9v3if05d5gopuakboe8hlud18rma/edit/F:/aicdita/aicdita-cn/topics/sdk/i2s/i2s_key_procedure.dita" > Edit online< / a > < / span > < h1 class = "- topic/title title topictitle1" id = "ariaid-title1" > 关键流程设计< / h1 > < div class = "date inPage" > 2 Dec 2024< / div > < div style = "color: gray;" >
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< / div > < div class = "- topic/body concept/conbody body conbody" > < section class = "- topic/section section" id = "i2s_key_procedures__section_nh2_5g3_d1c" data-ofbid = "i2s_key_procedures__section_nh2_5g3_d1c" > < h2 class = "- topic/title title sectiontitle" > 操作函数集实现< / h2 >
< p class = "- topic/p p" data-ofbid = "d303369e27__20250121171808" > 在 S 的驱动设计中， ， < / p >
< ol class = "- topic/ol ol" id = "i2s_key_procedures__ol_oh2_5g3_d1c" data-ofbid = "i2s_key_procedures__ol_oh2_5g3_d1c" > < li class = "- topic/li li" data-ofbid = "d303369e31__20250121171808" >
< p class = "- topic/p p" data-ofbid = "d303369e33__20250121171808" > cpu_dai 时钟配置函数，通常由 machine 驱动调用< / p >
< ul class = "- topic/ul ul" id = "i2s_key_procedures__ul_ph2_5g3_d1c" data-ofbid = "i2s_key_procedures__ul_ph2_5g3_d1c" > < li class = "- topic/li li" data-ofbid = "d303369e37__20250121171808" >
< p class = "- topic/p p" data-ofbid = "d303369e39__20250121171808" > set_sysclk： < / p >
< / li > < li class = "- topic/li li" data-ofbid = "d303369e42__20250121171808" >
< p class = "- topic/p p" data-ofbid = "d303369e44__20250121171808" > set_clkdiv： ， < / p >
< / li > < li class = "- topic/li li" data-ofbid = "d303369e47__20250121171808" >
< p class = "- topic/p p" data-ofbid = "d303369e49__20250121171808" > set_bclk_ratio： < / p >
< / li > < / ul >
< / li > < li class = "- topic/li li" data-ofbid = "d303369e53__20250121171808" >
< p class = "- topic/p p" data-ofbid = "d303369e55__20250121171808" > cpu_dai 格式设置，通常由 machine 驱动调用< / p >
< ul class = "- topic/ul ul" id = "i2s_key_procedures__ul_qh2_5g3_d1c" data-ofbid = "i2s_key_procedures__ul_qh2_5g3_d1c" > < li class = "- topic/li li" data-ofbid = "d303369e59__20250121171808" >
< p class = "- topic/p p" data-ofbid = "d303369e61__20250121171808" > set_fmt： ， < / p >
< / li > < li class = "- topic/li li" data-ofbid = "d303369e64__20250121171808" >
< p class = "- topic/p p" data-ofbid = "d303369e66__20250121171808" > set_tdm_slot： < / p >
< / li > < li class = "- topic/li li" data-ofbid = "d303369e69__20250121171808" >
< p class = "- topic/p p" data-ofbid = "d303369e71__20250121171808" > set_channel_map： < / p >
< / li > < / ul >
< / li > < li class = "- topic/li li" data-ofbid = "d303369e75__20250121171808" >
< p class = "- topic/p p" data-ofbid = "d303369e77__20250121171808" > ALSA PCM 音频操作，由 ALSA 的 soc-core 在执行音频操作时调用< / p >
< ul class = "- topic/ul ul" id = "i2s_key_procedures__ul_rh2_5g3_d1c" data-ofbid = "i2s_key_procedures__ul_rh2_5g3_d1c" > < li class = "- topic/li li" data-ofbid = "d303369e81__20250121171808" >
< p class = "- topic/p p" data-ofbid = "d303369e83__20250121171808" > hw_params： ， ， < / p >
< / li > < li class = "- topic/li li" data-ofbid = "d303369e86__20250121171808" >
< p class = "- topic/p p" data-ofbid = "d303369e88__20250121171808" > trigger： ， < / p >
< / li > < / ul >
< / li > < / ol >
< div class = "- topic/p p" data-ofbid = "d303369e93__20250121171808" > 在 S 的驱动中，需要实现的接口有：< pre class = "+ topic/pre pr-d/codeblock pre codeblock language-c" id = "i2s_key_procedures__codeblock_kzc_wg3_d1c" data-ofbid = "i2s_key_procedures__codeblock_kzc_wg3_d1c" > < strong class = "hl-keyword" > static< / strong > < strong class = "hl-keyword" > const< / strong > < strong class = "hl-keyword" > struct< / strong > snd_soc_dai_ops aic_i2s_dai_ops = {
.set_sysclk = aic_i2s_set_sysclk,
.set_bclk_ratio = aic_i2s_set_bclk_ratio,
.set_fmt = aic_i2s_set_fmt,
.set_tdm_slot = aic_i2s_set_tdm_slot,
.hw_params = aic_i2s_hw_params,
.trigger = aic_i2s_trigger,
};< / pre > < / div >
< p class = "- topic/p p" data-ofbid = "d303369e98__20250121171808" > 在实现的几个接口函数中，除 params 和 trigger 外，其它函数是需要在 machine 驱动中根据 I2S 和 codec 双方所支持的格式、时钟等进行调用设置的，使 S 和 codec 两边的格式设置相同。< / p >
< / section > < section class = "- topic/section section" id = "i2s_key_procedures__section_th2_5g3_d1c" data-ofbid = "i2s_key_procedures__section_th2_5g3_d1c" > < h2 class = "- topic/title title sectiontitle" > I2S 时钟设置< / h2 >
< div class = "- topic/p p" data-ofbid = "d303369e106__20250121171808" >
< ol class = "- topic/ol ol" id = "i2s_key_procedures__ol_v4j_xg3_d1c" data-ofbid = "i2s_key_procedures__ol_v4j_xg3_d1c" > < li class = "- topic/li li" data-ofbid = "d303369e109__20250121171808" > MCLK
主时钟设置。< p class = "- topic/p p" data-ofbid = "d303369e111__20250121171808" > MCLK 是 S 的主时钟，主要作用是向外部的 codec 芯片提供工作时钟，由 S 模块的工作时钟分频得到。在驱动中由 sysclk 设置 MCLK 的频率， ， ， ， ， < / p > < / li > < li class = "- topic/li li" data-ofbid = "d303369e113__20250121171808" > LRCK 和 BCLK
左右声道时钟设置。< p class = "- topic/p p" data-ofbid = "d303369e115__20250121171808" > LRCK 是左右声道时钟。LRCK 的时钟频率等于 fs， ， ， （ ） ， ， ， ， （ ） ， < / p > < / li > < li class = "- topic/li li" data-ofbid = "d303369e117__20250121171808" > period
bytes 对齐< div class = "- topic/p p" data-ofbid = "d303369e119__20250121171808" > 在使用 DMA 传输音频数据时， ， < pre class = "+ topic/pre pr-d/codeblock pre codeblock language-c" id = "i2s_key_procedures__codeblock_qd3_1h3_d1c" data-ofbid = "i2s_key_procedures__codeblock_qd3_1h3_d1c" > < strong class = "hl-keyword" > static< / strong > < strong class = "hl-keyword" > int< / strong > aic_i2s_startup(< strong class = "hl-keyword" > struct< / strong > snd_pcm_substream *substream,
< strong class = "hl-keyword" > struct< / strong > snd_soc_dai *dai)
{
< strong class = "hl-keyword" > int< / strong > ret;
< em class = "hl-comment" > /* Make sure that the period bytes are 8/128 bytes aligned according to
* the DMA transfer requested.
*/< / em >
< strong class = "hl-keyword" > if< / strong > (of_device_is_compatible(dai-> dev-> of_node,
< span class = "hl-string" > "artinchip,aic-i2s-v1.0"< / span > )) {
ret = snd_pcm_hw_constraint_step(substream-> runtime, < span class = "hl-number" > 0< / span > ,
SNDRV_PCM_HW_PARAM_PERIOD_BYTES, < span class = "hl-number" > 8< / span > );
< strong class = "hl-keyword" > if< / strong > (ret < < span class = "hl-number" > 0< / span > ) {
dev_err(dai-> dev,
< span class = "hl-string" > "Could not apply period step: %d\n"< / span > , ret);
< strong class = "hl-keyword" > return< / strong > ret;
}
ret = snd_pcm_hw_constraint_step(substream-> runtime, < span class = "hl-number" > 0< / span > ,
SNDRV_PCM_HW_PARAM_BUFFER_BYTES, < span class = "hl-number" > 8< / span > );
< strong class = "hl-keyword" > if< / strong > (ret < < span class = "hl-number" > 0< / span > ) {
dev_err(dai-> dev,
< span class = "hl-string" > "Could not apply buffer step: %d\n"< / span > , ret);
< strong class = "hl-keyword" > return< / strong > ret;
}
} < strong class = "hl-keyword" > else< / strong > {
ret = snd_pcm_hw_constraint_step(substream-> runtime, < span class = "hl-number" > 0< / span > ,
SNDRV_PCM_HW_PARAM_PERIOD_BYTES, < span class = "hl-number" > 128< / span > );
< strong class = "hl-keyword" > if< / strong > (ret < < span class = "hl-number" > 0< / span > ) {
dev_err(dai-> dev,
< span class = "hl-string" > "Could not apply period step: %d\n"< / span > , ret);
< strong class = "hl-keyword" > return< / strong > ret;
}
ret = snd_pcm_hw_constraint_step(substream-> runtime, < span class = "hl-number" > 0< / span > ,
SNDRV_PCM_HW_PARAM_BUFFER_BYTES, < span class = "hl-number" > 128< / span > );
< strong class = "hl-keyword" > if< / strong > (ret < < span class = "hl-number" > 0< / span > ) {
dev_err(dai-> dev,
< span class = "hl-string" > "Could not apply buffer step: %d\n"< / span > , ret);
< strong class = "hl-keyword" > return< / strong > ret;
}
}
< strong class = "hl-keyword" > return< / strong > ret;
}< / pre > < / div > < / li > < / ol >
< / div >
< / section > < section class = "- topic/section section" id = "i2s_key_procedures__section_bhv_2yl_4dc" data-ofbid = "i2s_key_procedures__section_bhv_2yl_4dc" > < h2 class = "- topic/title title sectiontitle" > < strong class = "+ topic/ph hi-d/b ph b" > Record 流程< / strong > < / h2 >
< ul class = "- topic/ul ul" id = "i2s_key_procedures__ul_xt4_fnf_fdc" data-ofbid = "i2s_key_procedures__ul_xt4_fnf_fdc" > < li class = "- topic/li li" data-ofbid = "d303369e132__20250121171808" >
< div class = "- topic/div div section" id = "i2s_key_procedures__id8" >
< strong class = "+ topic/ph hi-d/b ph b" > < code class = "+ topic/ph pr-d/codeph ph codeph" > init< / code > 流程< / strong >
< ol class = "- topic/ol ol arabic simple" id = "i2s_key_procedures__ol_fvg_kkf_fdc" data-ofbid = "i2s_key_procedures__ol_fvg_kkf_fdc" > < li class = "- topic/li li" data-ofbid = "d303369e142__20250121171808" >
< p class = "- topic/p p" data-ofbid = "d303369e144__20250121171808" > 初始化 DMA 传输的起始地址、< span class = "+ topic/keyword pr-d/parmname keyword parmname" > buf_len< / span > 以及
< span class = "+ topic/keyword pr-d/parmname keyword parmname" > period_len< / span > 。< / p >
< p class = "- topic/p p" data-ofbid = "d303369e153__20250121171808" > I2S 模块使用 DMA 传输音频数据，
传输时的起始地址（即 RX buffer 地址）以及
< span class = "+ topic/keyword pr-d/parmname keyword parmname" > buf_len< / span > ， < span class = "+ topic/keyword pr-d/parmname keyword parmname" > period_len< / span > 。< / p >
< / li > < li class = "- topic/li li" data-ofbid = "d303369e162__20250121171808" >
< p class = "- topic/p p" data-ofbid = "d303369e164__20250121171808" > 注册 HAL 层的回调函数。< / p >
< p class = "- topic/p p" data-ofbid = "d303369e167__20250121171808" > 在 Driver 层驱动，将 < span class = "+ topic/keyword pr-d/parmname keyword parmname" > buf_len< / span > 配置为
< span class = "+ topic/keyword pr-d/parmname keyword parmname" > period_len< / span > 的 2 倍，
< span class = "+ topic/keyword pr-d/parmname keyword parmname" > period_len< / span > 长度的数据，触发一次 DMA 中断，通知 CPU 向
pipe 设备写入数据。< / p >
< / li > < / ol > < / div >
< / li > < li class = "- topic/li li" data-ofbid = "d303369e180__20250121171808" >
< div class = "- topic/div div section" id = "i2s_key_procedures__id9" >
< strong class = "+ topic/ph hi-d/b ph b" > < code class = "+ topic/ph pr-d/codeph ph codeph" > start< / code > 流程< / strong >
< p class = "- topic/p p" data-ofbid = "d303369e189__20250121171808" > 按照 RT-Thread audio 的框架，在执行 < span class = "+ topic/keyword pr-d/apiname keyword apiname" > rt_device_open< / span > 时，就会调用
< code class = "+ topic/ph pr-d/codeph ph codeph" > start< / code > 流程，开始音频的录制，然后再通过
< span class = "+ topic/keyword pr-d/apiname keyword apiname" > rt_device_control< / span >
设置音频的格式（采样率，通道数等）。按照这个流程，最开始可能会录制一段不符合设置的音频格式的数据，这显然是不合理的。所以，在 Driver
层的驱动实现中，< code class = "+ topic/ph pr-d/codeph ph codeph" > start< / code >
流程并未做任何处理，而是在设置完音频格式后才开始音频的录制。< / p > < / div >
< / li > < li class = "- topic/li li" data-ofbid = "d303369e204__20250121171808" >
< div class = "- topic/div div section" id = "i2s_key_procedures__id10" >
< strong class = "+ topic/ph hi-d/b ph b" > DMA 中断流程< / strong >
< p class = "- topic/p p" data-ofbid = "d303369e211__20250121171808" > DMA 每传输完 < span class = "+ topic/keyword pr-d/parmname keyword parmname" > period_len< / span > 长度的数据后，触发一次 DMA 中断，然后通过 DMA
回调函数的逐级调用，最终调用 < span class = "+ topic/keyword pr-d/apiname keyword apiname" > rt_audio_rx_done< / span > ，将 RX buffer 的数据写入到
pipe 设备，每次写入 < span class = "+ topic/keyword pr-d/parmname keyword parmname" > period_len< / span > 长度的音频数据。< / p > < / div >
< / li > < / ul >
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< div class = " wh_topic_toc " > < div class = "wh_topic_label" > 在本页上< / div > < ul > < li class = "section-item" > < div class = "section-title" > < a href = "#i2s_key_procedures__section_nh2_5g3_d1c" data-tocid = "i2s_key_procedures__section_nh2_5g3_d1c" > 操作函数集实现< / a > < / div > < / li > < li class = "section-item" > < div class = "section-title" > < a href = "#i2s_key_procedures__section_th2_5g3_d1c" data-tocid = "i2s_key_procedures__section_th2_5g3_d1c" > I2S 时钟设置< / a > < / div > < / li > < li class = "section-item" > < div class = "section-title" > < a href = "#i2s_key_procedures__section_bhv_2yl_4dc" data-tocid = "i2s_key_procedures__section_bhv_2yl_4dc" > < strong class = "+ topic/ph hi-d/b ph b" > Record 流程< / strong > < / a > < / div > < / li > < / ul > < / div >
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< style > < ! - -
.p1 {
font-family: FangZhengShuSong, Times, serif;
}
.p2 {
font-family: Arial, Helvetica, sans-serif;
}
.p3 {
font-family: "Lucida Console", "Courier New", monospace;
}
-->< / style >
< div class = "webhelp.fragment.footer" >
< p class = "p1" > Copyright © 2019-2024 广东匠芯创科技有限公司. All rights reserved.< / p >
< / div > < div >
< div class = "generation_time" >
Update Time: 2025-01-21
< / div >
< / div >
< / div >
< / footer >
< div id = "go2top" class = "d-print-none" >
< span class = "oxy-icon oxy-icon-up" > < / span >
< / div >
< div id = "modal_img_large" class = "modal" >
< span class = "close oxy-icon oxy-icon-remove" > < / span >
< div id = "modal_img_container" > < / div >
< div id = "caption" > < / div >
< / div >
< script src = "${pd}/publishing/publishing-styles-AIC-template/js/custom.js" defer = "defer" > < / script >
< / body >
2025-01-23 16:37:00 +08:00
< / html >
