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研发客服一、实验环境
1.1 虚拟机环境
a) Vmware版本：Vmware Workstation 12.5.7
b) Ubuntu版本：9.10
c) 内核版本：2.6.31.14
d) toolchain版本：arm-linux-gcc 4.3.2
1.2 开发板
优龙FS2410开发板，UDA1341声卡
内核版本：3.4.2
二、编写代码
2.1 实现machine驱动的框架（s3c2440_uda1341.c）
（参考soundsocsamsungs3c24xx_uda134x.c）
1. 分配注册一个名为soc-audio的平台设备
2. 这个平台设备有一个私有数据 snd_soc_card，里面有一项snd_soc_dai_link，被用来决定ASOC各部分的驱动
static struct snd_soc_ops s3c2440_uda1341_ops = {
// .startup = s3c24xx_uda134x_startup, //从内核移植过来后，先暂时屏蔽掉这些函数，等用到的时候再加
// .shutdown = s3c24xx_uda134x_shutdown,
// .hw_params = s3c24xx_uda134x_hw_params,
};
static struct snd_soc_dai_link s3c2440_uda1341_dai_link = {
.name = "100ask_UDA1341",
.stream_name = "100ask_UDA1341",
.codec_name = "uda1341-codec", //必须和codec驱动的名字相同
.codec_dai_name = "uda1341-iis", //必须和codec_dai驱动的名字相同
.cpu_dai_name = "s3c2440-iis", //必须和cpu_dai驱动的名字相同
.ops = &s3c2440_uda1341_ops,
.platform_name = "s3c2440-dma",
};
static struct snd_soc_card myalsa_card = {
.name = "S3C2440_UDA1341",
.owner = THIS_MODULE,
.dai_link = &s3c2440_uda1341_dai_link, // snd_soc_dai_link被用来决定ASOC各部分的驱动
.num_links = 1,
};
static void asoc_release(struct device * dev)
{
}
static struct platform_device asoc_dev = {
.name = "soc-audio",
.id = -1,
.dev = {
.release = asoc_release,
},
};
static int s3c2440_uda1341_init(void)
{
platform_set_drvdata(&asoc_dev, &myalsa_card); //这个平台设备有一个私有数据 snd_soc_card
platform_device_register(&asoc_dev); //分配注册一个名为soc-audio的平台设备
return 0;
}
2.2 实现codec驱动的框架（uda1341.c）
（参考soundsoccodecsuda134x.c）
1. 构造一个snd_soc_dai_driver
static const struct snd_soc_dai_ops uda1341_dai_ops = {
// .startup = uda134x_startup, //从内核移植过来后，先暂时屏蔽掉这些函数，等用到的时候再加
// .shutdown = uda134x_shutdown,
// .hw_params = uda134x_hw_params,
// .digital_mute = uda134x_mute,
// .set_sysclk = uda134x_set_dai_sysclk,
// .set_fmt = uda134x_set_dai_fmt,
};
static struct snd_soc_dai_driver uda1341_dai = {
.name = "uda1341-iis", //必须和machine驱动的s3c2440_uda1341_dai_link.codec_dai_name一致
/* playback capabilities */
//playback和capture的各个属性值会被用于在soc_pcm_open里调用诸如 runtime->hw.rate_min = max(codec_dai_drv->playback.rate_min, cpu_dai_drv->playback.rate_min);
.playback = {
.stream_name = "Playback",
.channels_min = 1,
.channels_max = 2,
.rates = UDA134X_RATES,
.formats = UDA134X_FORMATS,
},
/* capture capabilities */
.capture = {
.stream_name = "Capture",
.channels_min = 1,
.channels_max = 2,
.rates = UDA134X_RATES,
.formats = UDA134X_FORMATS,
},
/* pcm operations */
.ops = &uda1341_dai_ops,
};
2. 构造一个snd_soc_codec_driver
static struct snd_soc_codec_driver soc_codec_dev_uda1341 = {
// .probe = uda134x_soc_probe, // 从内核移植过来后，先暂时屏蔽掉这些函数，等用到时候再加
// .remove = uda134x_soc_remove,
// .suspend = uda134x_soc_suspend,
// .resume = uda134x_soc_resume,
// .reg_cache_size = sizeof(uda134x_reg),
// .reg_word_size = sizeof(u8),
// .reg_cache_default = uda134x_reg,
// .reg_cache_step = 1,
// .read = uda134x_read_reg_cache,
// .write = uda134x_write,
// .set_bias_level = uda134x_set_bias_level,
};
3. 注册它们（一个小技巧：因为snd_soc_register_codec需要传入device参数，所以无法直接在uda1341_init()里调用snd_soc_register_codec，所以多绕一道弯子，通过注册platform_device、platform_driver，在其probe()函数中调用snd_soc_register_codec）
static struct platform_device uda1341_dev = {
.name = "uda1341-codec", //必须和machine驱动的s3c2440_uda1341_dai_link.codec_name一致
.id = -1,
.dev = {
.release = uda1341_dev_release,
},
};
struct platform_driver uda1341_drv = {
.probe = uda1341_probe, //在里面会调用snd_soc_register_codec注册codec驱动和codec_dai驱动
.remove = uda1341_remove,
.driver = {
.name = "uda1341-codec", //必须和uda1341_dev的name一致
}
};
static int uda1341_init(void)
{
platform_device_register(&uda1341_dev);
platform_driver_register(&uda1341_drv);
return 0;
}
static void uda1341_exit(void)
{
platform_device_unregister(&uda1341_dev);
platform_driver_unregister(&uda1341_drv);
}
module_init(uda1341_init);
module_exit(uda1341_exit);
MODULE_LICENSE("GPL");
2.3 实现cpu_dai驱动的框架（s3c2440_iis.c）
（参考soundsocsamsungs3c24xx-i2s.c）
1. 构造一个snd_soc_codec_driver
static const struct snd_soc_dai_ops s3c2440_i2s_dai_ops = {
//.trigger = s3c24xx_i2s_trigger, //从内核移植过来后，先暂时屏蔽掉这些函数，等用到的时候再加
// .hw_params = s3c24xx_i2s_hw_params,
// .set_fmt = s3c24xx_i2s_set_fmt,
// .set_clkdiv = s3c24xx_i2s_set_clkdiv,
// .set_sysclk = s3c24xx_i2s_set_syscl
};
#define S3C24XX_I2S_RATES
(SNDRV_PCM_RATE_8000 | SNDRV_PCM_RATE_11025 | SNDRV_PCM_RATE_16000 |
SNDRV_PCM_RATE_22050 | SNDRV_PCM_RATE_32000 | SNDRV_PCM_RATE_44100 |
SNDRV_PCM_RATE_48000 | SNDRV_PCM_RATE_88200 | SNDRV_PCM_RATE_96000)
static struct snd_soc_dai_driver s3c2440_i2s_dai = { //没有name，其实snd_soc_register_dai()里会把s3c2440_iis_dev的name复制给dai->name
// .probe = s3c24xx_i2s_probe, //从内核移植过来后，先暂时屏蔽掉这些函数，等用到时候再加
// .suspend = s3c24xx_i2s_suspend,
// .resume = s3c24xx_i2s_resum
.playback = {
.channels_min = 2,
.channels_max = 2,
.rates = S3C24XX_I2S_RATES,
.formats = SNDRV_PCM_FMTBIT_S8 | SNDRV_PCM_FMTBIT_S16_LE,},
.capture = {
.channels_min = 2,
.channels_max = 2,
.rates = S3C24XX_I2S_RATES,
.formats = SNDRV_PCM_FMTBIT_S8 | SNDRV_PCM_FMTBIT_S16_LE,},
.ops = &s3c2440_i2s_dai_ops,
};
2. 注册它
static int s3c2440_iis_probe(struct platform_device *pdev)
{
return snd_soc_register_dai(&pdev->dev, &s3c2440_i2s_dai);
}
static int s3c2440_iis_remove(struct platform_device *pdev)
{
snd_soc_unregister_dai(&pdev->dev);
return 0;
}
static void s3c2440_iis_release(struct device * dev)
{
}
static struct platform_device s3c2440_iis_dev = {
.name = "s3c2440-iis", //必须和machine驱动的s3c2440_uda1341_dai_link.cpu_dai_name一致
.id = -1,
.dev = {
.release = s3c2440_iis_release,
},
};
struct platform_driver s3c2440_iis_drv = {
.probe = s3c2440_iis_probe,
.remove = s3c2440_iis_remove,
.driver = {
.name = "s3c2440-iis", //必须和s3c2440_iis_dev的name一致
}
};
static int s3c2440_iis_init(void)
{
platform_device_register(&s3c2440_iis_dev);
platform_driver_register(&s3c2440_iis_drv);
return 0;
}
static void s3c2440_iis_exit(void)
{
struct clk *clk;
platform_device_unregister(&s3c2440_iis_dev);
platform_driver_unregister(&s3c2440_iis_drv);
}
static void s3c2440_iis_exit(void)
{
platform_device_unregister(&s3c2440_iis_dev);
platform_driver_unregister(&s3c2440_iis_drv);
}
module_init(s3c2440_iis_init);
module_exit(s3c2440_iis_exit);
MODULE_LICENSE("GPL");
2.4 实现platform驱动的框架（s3c2440_dma.c）
(参考 soundsocsamsungdma.c)
1. 构造一个snd_soc_platform_driver
static struct snd_pcm_ops dma_ops = {
// .open = dma_open, //从内核移植过来后，先暂时屏蔽掉这些函数，等用到的时候再加
// .close = dma_close,
// .ioctl = snd_pcm_lib_ioctl,
// .hw_params = dma_hw_params,
// .hw_free = dma_hw_free,
// .prepare = dma_prepare,
// .trigger = dma_trigger,
// .pointer = dma_pointer,
// .mmap = dma_mmap,
};
static struct snd_soc_platform_driver s3c2440_dma_platform = {
.ops = &s3c2440_dma_ops,
// .pcm_new = dma_new, //从内核移植过来后，先暂时屏蔽掉这些函数，等用到的时候再加
// .pcm_free = dma_free_dma_buffer
};
2. 注册它
static int s3c2440_dma_probe(struct platform_device *pdev)
{
return snd_soc_register_platform(&pdev->dev, &s3c2440_dma_platform);
}
static int s3c2440_dma_remove(struct platform_device *pdev)
{
snd_soc_unregister_platform(&pdev->dev);
return 0;
}
static void s3c2440_dma_release(struct device * dev)
{
}
static struct platform_device s3c2440_dma_dev = {
.name = "s3c2440-dma", //必须和machine驱动的s3c2440_uda1341_dai_link. platform_name一致
.id = -1,
.dev = {
.release = s3c2440_dma_release,
},
};
struct platform_driver s3c2440_dma_drv = {
.probe = s3c2440_dma_probe,
.remove = s3c2440_dma_remove,
.driver = {
.name = "s3c2440-dma", //必须和s3c2440_dma_dev的name一致
}
};
static int s3c2440_dma_init(void)
{
dma_regs = ioremap(DMA2_BASE_ADDR, sizeof(struct s3c_dma_regs));
platform_device_register(&s3c2440_dma_dev);
platform_driver_register(&s3c2440_dma_drv);
return 0;
}
static void s3c2440_dma_exit(void)
{
platform_device_unregister(&s3c2440_dma_dev);
platform_driver_unregister(&s3c2440_dma_drv);
iounmap(dma_regs);
}
module_init(s3c2440_dma_init);
module_exit(s3c2440_dma_exit);
MODULE_LICENSE("GPL");
三、参考资料
1. 韦东山 嵌入式Linux视频教程_3期项目实战之ALSA声卡：第2课第1.1_17节_ALSA声卡08_从零编写之框架
2. DroidPhone 《Linux ALSA 声卡驱动》