高通Audio中ASOC的codec驱动(二)
继上一篇文章:高通Audio中ASOC的machine驱动(一)
ASOC的出现是为了让codec独立于CPU,减少和CPU之间的耦合,这样同一个codec驱动就无需修改就可以匹配任何一款平台。
在Machine中已经知道,snd_soc_dai_link结构就指明了该Machine所使用的Platform和Codec。在Codec这边通过codec_dai和Platform侧的cpu_dai相互通信,既然相互通信,就需要遵守一定的规则,其中codec_dai和cpu_dai统一抽象为struct snd_soc_dai结构,而将dai的相关操作使用snd_soc_dai_driver抽象。同时也需要对所有的codec设备进行抽象封装,linux使用snd_soc_codec进行所有codec设备的抽象,而将codec的驱动抽象为snd_soc_codec_driver结构。
1、重要的数据结构:
所有简单来说,Codec侧有四个重要的数据结构:
struct snd_soc_dai,struct snd_soc_dai_driver,struct snd_soc_codec,struct snd_soc_codec_driver。
snd_soc_dai:
1 /* 2 * Digital Audio Interface runtime data. 3 * 4 * Holds runtime data for a DAI. 5 */ 6 struct snd_soc_dai { 7 const char *name; /* dai的名字 */ 8 struct device *dev; /* 设备指针 */ 9 10 /* driver ops */ 11 struct snd_soc_dai_driver *driver; /* 指向dai驱动结构的指针 */ 12 13 /* DAI runtime info */ 14 unsigned int capture_active:1; /* stream is in use */ 15 unsigned int playback_active:1; /* stream is in use */ 16 17 /* DAI DMA data */ 18 void *playback_dma_data; /* 用于管理playback dma */ 19 void *capture_dma_data; /* 用于管理capture dma */ 20 21 /* parent platform/codec */ 22 union { 23 struct snd_soc_platform *platform; /* 如果是cpu dai,指向所绑定的平台 */ 24 struct snd_soc_codec *codec; /* 如果是codec dai指向所绑定的codec */ 25 }; 26 struct snd_soc_card *card; /* 指向Machine驱动中的crad实例 */ 27 };
snd_soc_dai_driver:
1 /* 2 * Digital Audio Interface Driver. 3 * 4 * Describes the Digital Audio Interface in terms of its ALSA, DAI and AC97 5 * operations and capabilities. Codec and platform drivers will register this 6 * structure for every DAI they have. 7 * 8 * This structure covers the clocking, formating and ALSA operations for each 9 * interface. 10 */ 11 struct snd_soc_dai_driver { 12 /* DAI description */ 13 const char *name; /* dai驱动名字 */ 14 15 /* DAI driver callbacks */ 16 int (*probe)(struct snd_soc_dai *dai); /* dai驱动的probe函数,由snd_soc_instantiate_card回调 */ 17 int (*remove)(struct snd_soc_dai *dai); 18 int (*suspend)(struct snd_soc_dai *dai); /* 电源管理 */ 19 int (*resume)(struct snd_soc_dai *dai); 20 21 /* ops */ 22 const struct snd_soc_dai_ops *ops; /* 指向本dai的snd_soc_dai_ops结构 */ 23 24 /* DAI capabilities */ 25 struct snd_soc_pcm_stream capture; /* 描述capture的能力 */ 26 struct snd_soc_pcm_stream playback; /* 描述playback的能力 */ 27 };
snd_soc_codec:
1 /* SoC Audio Codec device */ 2 struct snd_soc_codec { 3 const char *name; /* Codec的名字*/ 4 struct device *dev; /* 指向Codec设备的指针 */ 5 const struct snd_soc_codec_driver *driver; /* 指向该codec的驱动的指针 */ 6 struct snd_soc_card *card; /* 指向Machine驱动的card实例 */ 7 int num_dai; /* 该Codec数字接口的个数,目前越来越多的Codec带有多个I2S或者是PCM接口 */ 8 int (*volatile_register)(...); /* 用于判定某一寄存器是否是volatile */ 9 int (*readable_register)(...); /* 用于判定某一寄存器是否可读 */ 10 int (*writable_register)(...); /* 用于判定某一寄存器是否可写 */ 11 12 /* runtime */ 13 ...... 14 /* codec IO */ 15 void *control_data; /* 该指针指向的结构用于对codec的控制,通常和read,write字段联合使用 */ 16 enum snd_soc_control_type control_type;/* 可以是SND_SOC_SPI,SND_SOC_I2C,SND_SOC_REGMAP中的一种 */ 17 unsigned int (*read)(struct snd_soc_codec *, unsigned int); /* 读取Codec寄存器的函数 */ 18 int (*write)(struct snd_soc_codec *, unsigned int, unsigned int); /* 写入Codec寄存器的函数 */ 19 /* dapm */ 20 struct snd_soc_dapm_context dapm; /* 用于DAPM控件 */ 21 };
snd_soc_codec_driver:
1 /* codec driver */ 2 struct snd_soc_codec_driver { 3 /* driver ops */ 4 int (*probe)(struct snd_soc_codec *); /* codec驱动的probe函数,由snd_soc_instantiate_card回调 */ 5 int (*remove)(struct snd_soc_codec *); 6 int (*suspend)(struct snd_soc_codec *); /* 电源管理 */ 7 int (*resume)(struct snd_soc_codec *); /* 电源管理 */ 8 9 /* Default control and setup, added after probe() is run */ 10 const struct snd_kcontrol_new *controls; /* 音频控件指针 */ 11 const struct snd_soc_dapm_widget *dapm_widgets; /* dapm部件指针 */ 12 const struct snd_soc_dapm_route *dapm_routes; /* dapm路由指针 */ 13 14 /* codec wide operations */ 15 int (*set_sysclk)(...); /* 时钟配置函数 */ 16 int (*set_pll)(...); /* 锁相环配置函数 */ 17 18 /* codec IO */ 19 unsigned int (*read)(...); /* 读取codec寄存器函数 */ 20 int (*write)(...); /* 写入codec寄存器函数 */ 21 int (*volatile_register)(...); /* 用于判定某一寄存器是否是volatile */ 22 int (*readable_register)(...); /* 用于判定某一寄存器是否可读 */ 23 int (*writable_register)(...); /* 用于判定某一寄存器是否可写 */ 24 25 /* codec bias level */ 26 int (*set_bias_level)(...); /* 偏置电压配置函数 */ 27 28 };
2、Codec代码分析:
2.1 找到codec的代码:
如何找到codec的代码呢? 答案是通过machine中的snd_soc_dai_link结构:
1 { 2 .name = LPASS_BE_TERT_MI2S_TX, 3 .stream_name = "Tertiary MI2S Capture", 4 .cpu_dai_name = "msm-dai-q6-mi2s.2", 5 .platform_name = "msm-pcm-routing", 6 .codec_name = MSM8X16_CODEC_NAME, 7 .codec_dai_name = "msm8x16_wcd_i2s_tx1", 8 .no_pcm = 1, 9 .be_id = MSM_BACKEND_DAI_TERTIARY_MI2S_TX, 10 .be_hw_params_fixup = msm_tx_be_hw_params_fixup, 11 .ops = &msm8x16_mi2s_be_ops, 12 .ignore_suspend = 1, 13 },
由dai_link中codec_name,可以知道我们的codec驱动在哪。
由高通Audio中ASOC的machine驱动这篇文章中的匹配并注册相应驱动的那一章分析可知,codec驱动代码就是msm8x16-wcd.c这个文件;
3、查看codec的probe函数:
因为Codec驱动的代码要做到平台无关性,要使得Machine驱动能够使用该Codec,Codec驱动的首要任务就是确定snd_soc_codec和snd_soc_dai的实例,并把它们注册到系统中,注册后的codec和dai才能为Machine驱动所用。
1 static int msm8x16_wcd_spmi_probe(struct spmi_device *spmi) 2 { 3 int ret = 0; 4 struct msm8x16_wcd *msm8x16 = NULL; 5 struct msm8x16_wcd_pdata *pdata; 6 struct resource *wcd_resource; 7 int modem_state; 8 9 dev_dbg(&spmi->dev, "%s(%d):slave ID = 0x%x\n", 10 __func__, __LINE__, spmi->sid); 11 12 modem_state = apr_get_modem_state(); 13 if (modem_state != APR_SUBSYS_LOADED) { 14 dev_dbg(&spmi->dev, "Modem is not loaded yet %d\n", 15 modem_state); 16 return -EPROBE_DEFER; 17 } 18 19 wcd_resource = spmi_get_resource(spmi, NULL, IORESOURCE_MEM, 0); 20 if (!wcd_resource) { 21 dev_err(&spmi->dev, "Unable to get Tombak base address\n"); 22 return -ENXIO; 23 } 24 25 switch (wcd_resource->start) { 26 case TOMBAK_CORE_0_SPMI_ADDR: 27 msm8x16_wcd_modules[0].spmi = spmi; 28 msm8x16_wcd_modules[0].base = (spmi->sid << 16) + 29 wcd_resource->start; 30 wcd9xxx_spmi_set_dev(msm8x16_wcd_modules[0].spmi, 0); 31 device_init_wakeup(&spmi->dev, true); 32 break; 33 case TOMBAK_CORE_1_SPMI_ADDR: 34 msm8x16_wcd_modules[1].spmi = spmi; 35 msm8x16_wcd_modules[1].base = (spmi->sid << 16) + 36 wcd_resource->start; 37 wcd9xxx_spmi_set_dev(msm8x16_wcd_modules[1].spmi, 1); 38 if (wcd9xxx_spmi_irq_init()) { 39 dev_err(&spmi->dev, 40 "%s: irq initialization failed\n", __func__); 41 } else { 42 dev_dbg(&spmi->dev, 43 "%s: irq initialization passed\n", __func__); 44 } 45 goto rtn; 46 default: 47 ret = -EINVAL; 48 goto rtn; 49 } 50 51 52 dev_dbg(&spmi->dev, "%s(%d):start addr = 0x%pa\n", 53 __func__, __LINE__, &wcd_resource->start); 54 55 if (wcd_resource->start != TOMBAK_CORE_0_SPMI_ADDR) 56 goto rtn; 57 58 dev_set_name(&spmi->dev, "%s", MSM8X16_CODEC_NAME); 59 if (spmi->dev.of_node) { 60 dev_dbg(&spmi->dev, "%s:Platform data from device tree\n", 61 __func__); 62 pdata = msm8x16_wcd_populate_dt_pdata(&spmi->dev); 63 spmi->dev.platform_data = pdata; 64 } else { 65 dev_dbg(&spmi->dev, "%s:Platform data from board file\n", 66 __func__); 67 pdata = spmi->dev.platform_data; 68 } 69 70 msm8x16 = kzalloc(sizeof(struct msm8x16_wcd), GFP_KERNEL); 71 if (msm8x16 == NULL) { 72 dev_err(&spmi->dev, 73 "%s: error, allocation failed\n", __func__); 74 ret = -ENOMEM; 75 goto rtn; 76 } 77 78 msm8x16->dev = &spmi->dev; 79 msm8x16->read_dev = __msm8x16_wcd_reg_read; 80 msm8x16->write_dev = __msm8x16_wcd_reg_write; 81 ret = msm8x16_wcd_init_supplies(msm8x16, pdata); 82 if (ret) { 83 dev_err(&spmi->dev, "%s: Fail to enable Codec supplies\n", 84 __func__); 85 goto err_codec; 86 } 87 88 ret = msm8x16_wcd_enable_static_supplies(msm8x16, pdata); 89 if (ret) { 90 dev_err(&spmi->dev, 91 "%s: Fail to enable Codec pre-reset supplies\n", 92 __func__); 93 goto err_codec; 94 } 95 usleep_range(5, 6); 96 97 ret = msm8x16_wcd_device_init(msm8x16); 98 if (ret) { 99 dev_err(&spmi->dev, 100 "%s:msm8x16_wcd_device_init failed with error %d\n", 101 __func__, ret); 102 goto err_supplies; 103 } 104 dev_set_drvdata(&spmi->dev, msm8x16); 105 106 ret = snd_soc_register_codec(&spmi->dev, &soc_codec_dev_msm8x16_wcd, 107 msm8x16_wcd_i2s_dai, 108 ARRAY_SIZE(msm8x16_wcd_i2s_dai)); 109 if (ret) { 110 dev_err(&spmi->dev, 111 "%s:snd_soc_register_codec failed with error %d\n", 112 __func__, ret); 113 } else { 114 goto rtn; 115 } 116 err_supplies: 117 msm8x16_wcd_disable_supplies(msm8x16, pdata); 118 err_codec: 119 kfree(msm8x16); 120 rtn: 121 return ret; 122 }
SPMI总线是高通电源管理的一种规范,也就是通过PMU控制音频(具体我也不够了解,有待以后深入理解)
看看最重要的函数:
1 ret = snd_soc_register_codec(&spmi->dev, &soc_codec_dev_msm8x16_wcd, 2 msm8x16_wcd_i2s_dai, 3 ARRAY_SIZE(msm8x16_wcd_i2s_dai));
此函数通过snd_soc_register_codec函数注册了wcd9320的codec,同时传入了snd_soc_codec_driver和snd_soc_dai_driver结构。
1 static struct snd_soc_codec_driver soc_codec_dev_msm8x16_wcd = { 2 .probe = msm8x16_wcd_codec_probe, /*codec驱动的probe函数,由snd_soc_instantiate_card回调*/ 3 .remove = msm8x16_wcd_codec_remove, 4 5 .read = msm8x16_wcd_read, 6 .write = msm8x16_wcd_write, 7 8 .suspend = msm8x16_wcd_suspend, /*电源管理*/ 9 .resume = msm8x16_wcd_resume, /*电源管理*/ 10 11 .readable_register = msm8x16_wcd_readable, 12 .volatile_register = msm8x16_wcd_volatile, 13 14 .reg_cache_size = MSM8X16_WCD_CACHE_SIZE, 15 .reg_cache_default = msm8x16_wcd_reset_reg_defaults, 16 .reg_word_size = 1, 17 18 .controls = msm8x16_wcd_snd_controls, 19 .num_controls = ARRAY_SIZE(msm8x16_wcd_snd_controls), 20 .dapm_widgets = msm8x16_wcd_dapm_widgets, 21 .num_dapm_widgets = ARRAY_SIZE(msm8x16_wcd_dapm_widgets), 22 .dapm_routes = audio_map, 23 .num_dapm_routes = ARRAY_SIZE(audio_map), 24 };
snd_soc_dai_driver结构:
1 static struct snd_soc_dai_driver msm8x16_wcd_i2s_dai[] = { 2 { 3 .name = "msm8x16_wcd_i2s_rx1", 4 .id = AIF1_PB, 5 .playback = { 6 .stream_name = "AIF1 Playback", 7 .rates = MSM8X16_WCD_RATES, 8 .formats = MSM8X16_WCD_FORMATS, 9 .rate_max = 192000, 10 .rate_min = 8000, 11 .channels_min = 1, 12 .channels_max = 3, 13 }, 14 .ops = &msm8x16_wcd_dai_ops, 15 }, 16 { 17 .name = "msm8x16_wcd_i2s_tx1", 18 .id = AIF1_CAP, 19 .capture = { 20 .stream_name = "AIF1 Capture", 21 .rates = MSM8X16_WCD_RATES, 22 .formats = MSM8X16_WCD_FORMATS, 23 .rate_max = 192000, 24 .rate_min = 8000, 25 .channels_min = 1, 26 .channels_max = 4, 27 }, 28 .ops = &msm8x16_wcd_dai_ops, 29 }, 30 };
4、snd_soc_register_codec函数分析:
首先,它申请了一个snd_soc_codec结构的实例:
1 codec = kzalloc(sizeof(struct snd_soc_codec), GFP_KERNEL);
确定codec的名字,这个名字很重要,Machine驱动定义的snd_soc_dai_link中会指定每个link的codec和dai的名字,进行匹配绑定时就是通过和这里的名字比较,从而找到该Codec的!
1 codec->name = fmt_single_name(dev, &codec->id);
然后初始化它的各个字段,多数字段的值来自上面定义的snd_soc_codec_driver的实例:
1 codec->write = codec_drv->write; 2 codec->read = codec_drv->read; 3 codec->volatile_register = codec_drv->volatile_register; 4 codec->readable_register = codec_drv->readable_register; 5 codec->writable_register = codec_drv->writable_register; 6 codec->ignore_pmdown_time = codec_drv->ignore_pmdown_time; 7 codec->dapm.bias_level = SND_SOC_BIAS_OFF; 8 codec->dapm.dev = dev; 9 codec->dapm.codec = codec; 10 codec->dapm.seq_notifier = codec_drv->seq_notifier; 11 codec->dapm.stream_event = codec_drv->stream_event; 12 codec->dev = dev; 13 codec->driver = codec_drv; 14 codec->num_dai = num_dai;
在做了一些寄存器缓存的初始化和配置工作后,通过snd_soc_register_dais函数对本Codec的dai进行注册:
1 /* register any DAIs */ 2 ret = snd_soc_register_dais(dev, dai_drv, num_dai); 3 if (ret < 0) { 4 dev_err(codec->dev, "ASoC: Failed to regster DAIs: %d\n", ret); 5 goto fail_codec_name; 6 }
它把codec实例链接到全局链表codec_list中:
1 mutex_lock(&client_mutex); 2 list_add(&codec->list, &codec_list); 3 mutex_unlock(&client_mutex);
并且调用snd_soc_instantiate_cards对machine驱动进行一次匹配绑定的操作;
至此,codec的注册就分析完毕。
关于codec侧驱动总结:
1. 分配名字为"codec_name"的平台驱动,注册。
2. 定义struct snd_soc_codec_driver结构,设置,初始化。
2. 定义struct snd_soc_codec_driver结构,设置,初始化。
3. 定义struct snd_soc_dai_driver结构,设置,初始化。
4. 调用snd_soc_register_codec函数注册codec。