对于声卡的dai部分，因为i2s是rk3568侧的通讯总线，所以我们对于i2s的控制器这侧也需要配置正确，这样rk3568的i2s发送音频数据的时候，es8388能够正常的接收，所以有必要介绍一下rk侧的i2s的驱动，也就是dai驱动

一、代码目录

对于i2s的驱动，代码路径如下：

device/board/hihope/rk3568/audio_drivers/dai/

相应文件如下：

rk3568_dai_adapter.c  rk3568_dai_linux_driver.c  rk3568_dai_ops.c

二、代码解析

2.1 rk3568_dai_linux_driver.c

此驱动主要注册platfrom设备，读取dts的配置，设置时钟和分频，大致如下

static struct platform_driver rockchip_i2s_tdm_driver = {
    .probe = rockchip_i2s_tdm_probe,
    .remove = rockchip_i2s_tdm_remove,
    .driver = {
        .name = DRV_NAME,
        .of_match_table = of_match_ptr(rockchip_i2s_tdm_match),
        .pm = NULL,
    },
};
module_platform_driver(rockchip_i2s_tdm_driver);
 
 
static int rockchip_i2s_tdm_probe(struct platform_device *pdev)
{
    struct device_node *node = pdev->dev.of_node;
    const struct of_device_id *of_id;
    struct rk3568_i2s_tdm_dev *i2s_tdm;
    struct resource *res;
    struct device *temp_i2s_dev;
 
......
    i2s_tdm->bclk_fs = 64; // default-freq div factor is 64
    if (!of_property_read_u32(node, "rockchip,bclk-fs", &val)) {
        if ((val >= 32) && (val % 2 == 0)) // min-freq div factor is 32, and it is an integer multiple of 2
            i2s_tdm->bclk_fs = val;
    }
......
    i2s_tdm->mclk_tx = devm_clk_get(&pdev->dev, "mclk_tx");
    if (IS_ERR(i2s_tdm->mclk_tx)) {
        return PTR_ERR(i2s_tdm->mclk_tx);
    }
 
    i2s_tdm->mclk_rx = devm_clk_get(&pdev->dev, "mclk_rx");
    if (IS_ERR(i2s_tdm->mclk_rx)) {
        return PTR_ERR(i2s_tdm->mclk_rx);
    }
 
    res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 
    i2s_tdm->regmap = devm_regmap_init_mmio(&pdev->dev, devm_ioremap_resource(&pdev->dev, res),
        &rockchip_i2s_tdm_regmap_config);
    if (IS_ERR(i2s_tdm->regmap)) {
        return PTR_ERR(i2s_tdm->regmap);
    }
......
}

2.2 rk3568_dai_adapter.c

这份驱动是hdf的驱动程序，它通过HDF_INIT(g_daiDriverEntry);来注册一个hdf的驱动

/* HdfDriverEntry definitions */
struct HdfDriverEntry g_daiDriverEntry = {
    .moduleVersion = 1,
    .moduleName = "DAI_RK3568",
    .Bind = DaiDriverBind,
    .Init = DaiDriverInit,
    .Release = DaiDriverRelease,
};
HDF_INIT(g_daiDriverEntry);

对于Bind回调，绑定服务，对于Init，用作注册dai，如下

daiData = (struct DaiData *)OsalMemCalloc(sizeof(*daiData));
if (daiData == NULL) {
    AUDIO_DEVICE_LOG_ERR("malloc DaiData fail!");
    return HDF_FAILURE;
}
daiData->Read = Rk3568DeviceReadReg,
daiData->Write = Rk3568DeviceWriteReg,
daiData->DaiInit = Rk3568DaiDeviceInit,
daiData->ops = &g_daiDeviceOps,
daiData->daiInitFlag = false;
OsalMutexInit(&daiData->mutex);
daiHost->priv = daiData;
 
if (DaiGetConfigInfo(device, daiData) !=  HDF_SUCCESS) {
    AUDIO_DEVICE_LOG_ERR("get dai data fail.");
    OsalMemFree(daiData);
    return HDF_FAILURE;
}
 
if (DaiGetServiceName(device, daiData) !=  HDF_SUCCESS) {
    AUDIO_DEVICE_LOG_ERR("get service name fail.");
    OsalMemFree(daiData);
    return HDF_FAILURE;
}
 
ret = AudioSocRegisterDai(device, (void *)daiData);

所以这里涉及一个dai的结构体，用于触发startup和hwparams以及trigger时的i2s的寄存器设置，如下：

struct AudioDaiOps g_daiDeviceOps = {
    .Startup = Rk3568DaiStartup,
    .HwParams = Rk3568DaiHwParams,
    .Trigger = Rk3568NormalTrigger,
};

2.3 rk3568_dai_ops.c

对于startup回调，这里i2s不需要做任何事情

对于hwparams回调，这里需要根据实际的参数，设置i2s的寄存器，时钟，如下：

int32_t Rk3568DaiHwParams(const struct AudioCard *card, const struct AudioPcmHwParams *param)
{
    int ret;
    uint32_t bitWidth;
    struct DaiDevice *dai = NULL;
    struct DaiData *data = DaiDataFromCard(card);
    struct platform_device *platformdev = NULL;
    struct rk3568_i2s_tdm_dev *i2sTdm = NULL;
 
    if (card == NULL || card->rtd == NULL || param == NULL || param->cardServiceName == NULL) {
        AUDIO_DEVICE_LOG_ERR("input para is NULL.");
        return HDF_ERR_INVALID_PARAM;
    }
    if (data == NULL) {
        AUDIO_DEVICE_LOG_ERR("data is nullptr.");
        return HDF_FAILURE;
    }
    dai = card->rtd->cpuDai;
    platformdev = GetPlatformDev(dai);
    if (platformdev == NULL) {
        AUDIO_DEVICE_LOG_ERR("platformdev is NULL.");
        return HDF_FAILURE;
    }
    data->pcmInfo.channels = param->channels;
 
    AUDIO_DEVICE_LOG_DEBUG("channels count : %d .", param->channels);
    if (AudioFormatToBitWidth(param->format, &bitWidth) != HDF_SUCCESS) {
        AUDIO_DEVICE_LOG_ERR("AudioFormatToBitWidth error");
        return HDF_FAILURE;
    }
    data->pcmInfo.bitWidth = bitWidth;
    data->pcmInfo.rate = param->rate;
    data->pcmInfo.streamType = param->streamType;
 
    i2sTdm = dev_get_drvdata(&platformdev->dev);
    if (i2sTdm == NULL) {
        AUDIO_DEVICE_LOG_ERR("i2sTdm is null");
        return HDF_FAILURE;
    }
    ret = RK3568I2sTdmSetSysClk(i2sTdm, param);
    if (ret != HDF_SUCCESS) {
        AUDIO_DEVICE_LOG_ERR("RK3568I2sTdmSetSysClk error");
        return HDF_FAILURE;
    }
    ret = RK3568I2sTdmSetMclk(i2sTdm, param);
    if (ret != HDF_SUCCESS) {
        AUDIO_DEVICE_LOG_ERR("RK3568I2sTdmSetMclk error");
        return HDF_FAILURE;
    }
    AUDIO_DEVICE_LOG_DEBUG("success");
    return HDF_SUCCESS;
}

对于trigger回调，判断是否是stop/pause，start/resume，来控制i2s的寄存器，如下

static int32_t Rk3568TxAndRxSetReg(struct rk3568_i2s_tdm_dev *i2sTdm,
    enum AudioStreamType streamType, int on)
{
    int ret;
 
    if (i2sTdm == NULL || i2sTdm->regmap == NULL) {
        AUDIO_DEVICE_LOG_ERR("i2sTdm is null");
        return HDF_FAILURE;
    }
 
    if (on) {       // when start/resume
        ret = Rk3568TxAndRxStart(i2sTdm, streamType);
        if (ret != HDF_SUCCESS) {
            AUDIO_DEVICE_LOG_ERR("Rk3568TxAndRxStart is failed");
            return HDF_FAILURE;
        }
    } else {     // when stop/pause
        ret = Rk3568TxAndRxStop(i2sTdm, streamType);
        if (ret != HDF_SUCCESS) {
            AUDIO_DEVICE_LOG_ERR("Rk3568TxAndRxStop is failed");
            return HDF_FAILURE;
        }
    }
 
    AUDIO_DEVICE_LOG_DEBUG("success");
    return HDF_SUCCESS;
}

三、总结

至此，rk3568的i2s的hdf驱动解析完成，我们可以知道，对于i2s，我们应该在合适的时候对其设置rk3568这侧的寄存器，让其按照指定的方式和codec进行通讯，所以需要这么一个hdf driver。