Linux内核注册一个声卡的示例

Linux 内核中注册声卡的示例如下：

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <sound/core.h>
#include <sound/pcm.h>
#include <sound/pcm_params.h>
#include <sound/soc.h>
#include <sound/initval.h>

static int my_card_register(struct snd_soc_card *card)
{
    int ret;
    struct snd_soc_dai_link *dai_link;
    struct snd_soc_dai *dai;

    dai_link = devm_kzalloc(card->dev, sizeof(*dai_link), GFP_KERNEL);
    if (!dai_link)
        return -ENOMEM;

    dai_link->name = "My Card";
    dai_link->stream_name = "My Card";
    dai_link->platform_name = "platform-name";
    dai_link->codec_name = "codec-name";
    dai_link->codec_dai_name = "codec-dai-name";
    dai_link->cpu_dai_name = "cpu-dai-name";

    dai = asoc_rtd_to_codec(rtd, 0);
    dai->driver->playback.channels_min = 2;
    dai->driver->playback.channels_max = 2;
    dai->driver->capture.channels_min = 2;
    dai->driver->capture.channels_max = 2;

    ret = snd_soc_register_card(card);
    if (ret) {
        dev_err(card->dev, "snd_soc_register_card() failed: %d\n", ret);
        return ret;
    }

    return 0;
}

static int my_driver_probe(struct platform_device *pdev)
{
    struct snd_soc_card *card;
    int ret;

    card = devm_kzalloc(&pdev->dev, sizeof(*card), GFP_KERNEL);
    if (!card)
        return -ENOMEM;

    card->dev = &pdev->dev;
    card->owner = THIS_MODULE;

    ret = my_card_register(card);
    if (ret)
        return ret;

    platform_set_drvdata(pdev, card);

    return 0;
}

static int my_driver_remove(struct platform_device *pdev)
{
    struct snd_soc_card *card = platform_get_drvdata(pdev);

    snd_soc_unregister_card(card);

    return 0;
}

static const struct of_device_id my_of_match[] = {
    { .compatible = "my-card" },
    {},
};
MODULE_DEVICE_TABLE(of, my_of_match);

static struct platform_driver my_driver = {