[Linux Audio Driver] Android 10 machine driver probe函数分析

0. 背景

平台：Qualcomm 5G SM6350、android10、kernel version： msm-4.19。

本文重点分析machine driver里面的msm_asoc_machine_probe函数，这个是machie驱动的核心代码，涉及声卡解析注册，CPU dai和codec dai绑定，麦克偏置解析配置routing、耳机麦克检测（欧-美标兼容）、MI2S主、从模式配置，以及新增的LPASS音频投票机制。

此外，msm_asoc_machine_probe函数也可以说就干了一件事：
实例化结构体snd_soc_card。

那个，兄弟们转载博客还是希望附上我的转载链接啊，不要直接copy，也是尊重人不是 -_-。

1. msm_asoc_machine_probe

代码位置：

./vendor/qcom/opensource/audio-kernel/asoc/kona.c

msm_asoc_machine_probe整个函数如下：

static int msm_asoc_machine_probe(struct platform_device *pdev)
{
   
   
	struct snd_soc_card *card = NULL;
	struct msm_asoc_mach_data *pdata = NULL;
	const char *mbhc_audio_jack_type = NULL;
	int ret = 0;
	uint index = 0;
	struct clk *lpass_audio_hw_vote = NULL;

	if (!pdev->dev.of_node) {
   
   
		dev_err(&pdev->dev, "%s: No platform supplied from device tree\n", __func__);
		return -EINVAL;
	}

	pdata = devm_kzalloc(&pdev->dev,
			sizeof(struct msm_asoc_mach_data), GFP_KERNEL);
	if (!pdata)
		return -ENOMEM;

	of_property_read_u32(pdev->dev.of_node,
				"qcom,lito-is-v2-enabled",
				&pdata->lito_v2_enabled);


	card = populate_snd_card_dailinks(&pdev->dev);
	if (!card) {
   
   
		dev_err(&pdev->dev, "%s: Card uninitialized\n", __func__);
		ret = -EINVAL;
		goto err;
	}

	card->dev = &pdev->dev;
	platform_set_drvdata(pdev, card);
	snd_soc_card_set_drvdata(card, pdata);

	ret = snd_soc_of_parse_card_name(card, "qcom,model");
	if (ret) {
   
   
		dev_err(&pdev->dev, "%s: parse card name failed, err:%d\n",
			__func__, ret);
		goto err;
	}


	ret = snd_soc_of_parse_audio_routing(card, "qcom,audio-routing");
	if (ret) {
   
   
		dev_err(&pdev->dev, "%s: parse audio routing failed, err:%d\n",
			__func__, ret);
		goto err;
	}


	ret = msm_populate_dai_link_component_of_node(card);
	if (ret) {
   
   
		ret = -EPROBE_DEFER;
		goto err;
	}


	ret = msm_init_aux_dev(pdev, card);
	if (ret)
		goto err;


	ret = devm_snd_soc_register_card(&pdev->dev, card);
	if (ret == -EPROBE_DEFER) {
   
   
		if (codec_reg_done)
			ret = -EINVAL;
		goto err;
	} else if (ret) {
   
   
		dev_err(&pdev->dev, "%s: snd_soc_register_card failed (%d)\n",
			__func__, ret);
		goto err;
	}
	dev_err(&pdev->dev, "%s: Sound card %s registered\n", __func__, card->name);


	kona_parse_aw87xx_mode(pdev, pdata);
	pdata->spk_ext_pa_gpio_p = of_parse_phandle(pdev->dev.of_node, 
	"qcom,msm-spk-ext-pa-gpios", 0);
	if (!pdata->spk_ext_pa_gpio_p) {
   
   
		pr_err("%s: property %s not detected in node %s\n", __func__, 
		"qcom,msm-spk-ext-pa-gpios", pdev->dev.of_node->full_name);
	}else{
   
   
		ret = msm_cdc_pinctrl_select_sleep_state(pdata->spk_ext_pa_gpio_p);
		if (ret < 0) {
   
   
			pr_err("%s: gpio set cannot be activated %s\n", __func__, "speaker_pa_gpio");
			return ret;
		}
	}

	ret = of_property_read_u32(pdev->dev.of_node, "qcom,tdm-max-slots",
				   &pdata->tdm_max_slots);
	if (ret) {
   
   
		dev_err(&pdev->dev, "%s: No DT match for tdm max slots\n",
			__func__);
	}
	if ((pdata->tdm_max_slots <= 0) || (pdata->tdm_max_slots >
	    TDM_MAX_SLOTS)) {
   
   
		pdata->tdm_max_slots = TDM_MAX_SLOTS;
		dev_err(&pdev->dev, "%s: Using default tdm max slot: %d\n",
			__func__, pdata->tdm_max_slots);
	}

	pdata->hph_en1_gpio_p = of_parse_phandle(pdev->dev.of_node,
						"qcom,hph-en1-gpio", 0);
	if (!pdata->hph_en1_gpio_p) {
   
   
		dev_dbg(&pdev->dev, "%s: property %s not detected in node %s\n",
			__func__, "qcom,hph-en1-gpio",
			pdev->dev.of_node->full_name);
	}

	pdata->hph_en0_gpio_p = of_parse_phandle(pdev->dev.of_node,
						"qcom,hph-en0-gpio", 0);
	if (!pdata->hph_en0_gpio_p) {
   
   
		dev_dbg(&pdev->dev,