一、環境介紹

linux 版本：6.6.52

soc：imx9331

codec：nau88c10

使用的內核文件為 Image，dtb 文件為：imx93-11x11-evk.dtb

二、硬件檢查

• i2s 信號線要接對

• i2c 控制信號建議為 4.7k 上拉

• codec 供電可以按參考設計來

三、驅動修改

先配置 sai 信號，我的板子使用的是 sai2，所以我配置如下

&sai2 {
	pinctrl-names = "default", "sleep";
	pinctrl-0 = <&pinctrl_sai2>;
	pinctrl-1 = <&pinctrl_sai2_sleep>;
	assigned-clocks = <&clk IMX93_CLK_SAI2>;
	assigned-clock-parents = <&clk IMX93_CLK_AUDIO_PLL>;
	assigned-clock-rates = <12288000>;
	fsl,sai-mclk-direction-output;
	status = "okay";
};

	pinctrl_sai2: sai2grp {
		fsl,pins = <
			MX93_PAD_ENET2_TX_CTL__SAI2_TX_SYNC		0x31e
			MX93_PAD_ENET2_TXC__SAI2_TX_BCLK		0x31e
			MX93_PAD_ENET2_RD2__SAI2_MCLK			0x31e
			MX93_PAD_ENET2_RX_CTL__SAI2_TX_DATA00	0x31e
			MX93_PAD_ENET2_TD3__SAI2_RX_DATA00		0x31e
		>;
	};

	pinctrl_sai2_sleep: sai2grpsleep {
		fsl,pins = <
			MX93_PAD_ENET2_TX_CTL__GPIO4_IO20		0x51e
			MX93_PAD_ENET2_TXC__GPIO4_IO21			0x51e
			MX93_PAD_ENET2_RD2__GPIO4_IO26			0x51e
			MX93_PAD_ENET2_RX_CTL__GPIO4_IO22		0x51e
			MX93_PAD_ENET2_TD3__GPIO4_IO16			0x51e
		>;
	};

再配置 codec，codec 的 7 位讀寫地址為 0x1a；因為要用到 imx9331 給的 mclk；所以添加了一個時鐘配置

&lpi2c1 {
	#address-cells = <1>;
	#size-cells = <0>;
	clock-frequency = <400000>;
	pinctrl-names = "default", "sleep";
	pinctrl-0 = <&pinctrl_lpi2c1>;
	pinctrl-1 = <&pinctrl_lpi2c1>;
	status = "okay";

	codec: nau8810@1a {
		#sound-dai-cells = <0>;
		compatible = "nuvoton,nau8810";
		reg = <0x1a>;

		clocks = <&clk IMX93_CLK_SAI2>;
		clock-name = "mclk";
	};
};

再配置 machine 驅動的硬件信息，參考原先的 codec，修改如下

audio-routing 是更具 machine 驅動，和 codec 驅動的 struct snd_soc_dapm_widget 來填寫的；

	sound-nau8810 {
		compatible = "fsl,imx-audio-nau8810";
		model = "nau8810-audio";
		audio-cpu = <&sai2>;
		audio-codec = <&codec>;
		audio-routing =
			"Ext Spk", "MONOOUT",
			"Ext Spk", "SPKOUTP",
			"Ext Spk", "SPKOUTN",
			"AMIC", "MICN",
			"AMIC", "MICP";
	};

 修改 machine 驅動，更具參考板的 compatible 字符串，找到驅動 fsl-asoc-card.c

// 添加頭文件
#include "../codecs/nau8810.h"

// 注釋掉以下代碼
static int fsl_asoc_card_hw_free(struct snd_pcm_substream *substream)
{
    ......
#if 0
		ret = snd_soc_dai_set_pll(asoc_rtd_to_codec(rtd, 0),
					  codec_priv->pll_id, 0, 0, 0);
		if (ret && ret != -ENOTSUPP) {
			dev_err(dev, "failed to stop FLL: %d\n", ret);
			return ret;
		}
#endif
    ......
}

// 添加聲卡 nau8810 的信息
static int fsl_asoc_card_probe(struct platform_device *pdev)
{
    ......
	} else if (of_device_is_compatible(np, "fsl,imx-audio-wm8904")) {
		codec_dai_name = "wm8904-hifi";
		priv->codec_priv.mclk_id = WM8904_FLL_MCLK;
		priv->codec_priv.fll_id = WM8904_CLK_FLL;
		priv->codec_priv.pll_id = WM8904_FLL_MCLK;
		priv->dai_fmt |= SND_SOC_DAIFMT_CBP_CFP;
		priv->card_type = CARD_WM8904;
	} else if (of_device_is_compatible(np, "fsl,imx-audio-nau8810")) {
		codec_dai_name = "nau8810-hifi";
		priv->codec_priv.mclk_id = NAU8810_SCLK_MCLK;
		priv->codec_priv.fll_id = NAU8810_SCLK_PLL;
		priv->codec_priv.pll_id = NAU8810_SCLK_PLL;
		priv->dai_fmt |= SND_SOC_DAIFMT_CBM_CFM;
		if (codec_dev) {
			priv->codec_priv.mclk = devm_clk_get(codec_dev, NULL);
			printk("trans mclk rate %ld\n", clk_get_rate(priv->codec_priv.mclk));
		}
	} else {
		dev_err(&pdev->dev, "unknown Device Tree compatible\n");
		ret = -EINVAL;
		goto asrc_fail;
	}
	......
}

四、測試聲卡

可以通過 alsa 工具來測試聲卡

# 顯示所有可以配置的控件
amixer controls

# SPKOUT 非靜音
amixer cset numid=36 off
# SPKOUT 靜音
amixer cset numid=36 on

# MONOOUT 非靜音
amixer cset numid=39 off
# MONOOUT 靜音
amixer cset numid=39 on

# 調整 MONOOUT 音量（SPKOUT 也會被一起調節）
amixer cset numid=7 220

# 調整 MIC 音量
amixer cset numid=11 230

# 調整 SPKOUT 音量
amixer cset numid=37 63

# 邊錄邊放
arecord -f S16_LE -r 8000 -c 2 | aplay -