AM335x(TQ335x)学习笔记——WM8960声卡驱动移植
2016-04-21 23:42
113 查看
经过一段时间的调试，终于调好了TQ335x的声卡驱动。TQ335x采用的Codec是WM8960，本文来总结下WM8960驱动在AM335x平台上的移植方法。Linux声卡驱动架构有OSS和ALSA两种架构，目前最常用的架构是ALSA，本文也使用ALSA架构对WM8960驱动进行移植。
ASoC是对ALSA驱动架构的进一步封装。ASoC将ALSA驱动中的各模块抽象为三部分：Platform、Codec和Machine。Platform主要是平台硬件驱动，包括SoC的IIS模块、DMA等，在本文中就是指AM335x的McASP模块及AM335x用于音频读写操作的EDMA。Codec是编解码芯片驱动，在本文中就是WM8960。Machine是用来描述单板音频系统连接关系的驱动，在本文中其作用是将WM8960与McASP绑定起来，注册声卡设备节点。由于3.17版本的内核已经带有TI维护的McASP驱动和Wolf公司维护的WM8960驱动，因此，原理上讲，我们只需要编写Machine部分，建立WM8960与McASP的连接关系即可。不幸的是Wolf对WM8960的维护不是太完善，还需要我们进一步修改。下面我们来看下WM8960在TQ335x上的移植方法。
1. 在DTS中添加声卡信息
Step1. 完善sound信息
在DTS有一个节点名为sound，该节点用来描述单板上声卡设备信息，修改后的内容如下：
[cpp]
view plain
copy
sound {
compatible = "ti,tq-evm-audio";
ti,model = "AM335x-EVM";
ti,audio-codec = <&wm8960>;
ti,mcasp-controller = <&mcasp1>;
ti,codec-clock-rate = <24576000>;
ti,audio-routing =
"Headphone Jack", "HP_L",
"Headphone Jack", "HP_R",
"LINPUT1", "Line In";
};
含义解释：
(1) compatible = "ti,tq-evm-audio" --> 指定声卡兼容的设备，与Machine驱动中的compatible匹配。
(2) ti,model = "AM335x-EVM" --> 声卡的名称，原则上讲可以随意指定，但最好具有一定的可读性，这里没有修改。
(3) ti,audio-codec = <&wm8960> --> 指定单板使用的Codec，具体的Codec信息由其指向的节点wm8960描述。
(4) ti,mcasp-controller = <&mcasp1> --> 指定单板使用的Codec连接到AM335x的McASP1上，McASP1的具体信息由其指向的节点mcasp1描述。
(5) ti,codec-clock-rate = <24576000> --> 指定Codec的MCLK时钟频率，单位是HZ。TQ335x的Codec使用24.576MHZ的有源晶振提供MCLK，故设置为24576000。
(6) ti,audio-routing --> DAPM信息描述，用来指定Codec与McASP的连接关系。此处若不设置，则需要在Machine驱动中进行设置。本文在这里做了修改。
Step2. 完善Codec信息
通过阅读TQ335x的原理图可知，WM8960的控制端口连接到了AM335x的I2C0端口上，因此，可以i2c0节点内添加如下信息（类似上篇文章中触摸设备驱动节点）：
[cpp]
view plain
copy
wm8960: wm8960@1a {
compatible = "wlf,wm8960";
reg = <0x1a>;
};
含义解释：
(1) compatible = "wlf,wm8960" --> 指定Codec兼容设备，与Codec驱动中的compatible匹配。
(2) reg = <0x1a> --> WM8960的I2C地址是1A，故设置为0x1a。
Step3. 完善Platform信息
AM335x的Platform信息主要指McASP和EMDA设置信息。由于默认的DTS已经配置好了McASP及EDMA的大部分信息，需要我们配置的是McASP的pinmux和i2s信息。
(1) 修改pinmux信息需要具体参考TQ335x的原理图，下面是根据原理图中的引脚连接方式修改的pinmux信息，如果有啥不懂的可以留言讨论：
[cpp]
view plain
copy
am335x_evm_audio_pins: am335x_evm_audio_pins {
pinctrl-single,pins = <
0x1A0 (PIN_INPUT_PULLDOWN | MUX_MODE3) /* mcasp0_aclkr.mcasp1_aclkx */
0x1A4 (PIN_INPUT_PULLDOWN | MUX_MODE3) /* mcasp0_fsr.mcasp1_fsx */
0x1A8 (PIN_OUTPUT_PULLDOWN | MUX_MODE3) /* mcasp0_axr1.mcasp1_axr0 */
0x1AC (PIN_INPUT_PULLDOWN | MUX_MODE3) /* mcasp0_ahclkx.mcasp1_axr1 */
>;
};
(2) i2s的配置信息需要在mcasp1节点中修改，具体的修改如下：
[cpp]
view plain
copy
&mcasp1 {
pinctrl-names = "default";
pinctrl-0 = <&am335x_evm_audio_pins>;
status = "okay";
op-mode = <0>; /* MCASP_IIS_MODE */
tdm-slots = <2>;
/* 4 serializers */
serial-dir = < /* 0: INACTIVE, 1: TX, 2: RX */
1 2 0 0
>;
tx-num-evt = <1>;
rx-num-evt = <1>;
};
含义：
(1) pinctrl-0 = <&am335x_evm_audio_pins> --> 指定mcasp1的pinmux信息。
(2) op-mode = <0> --> 指定McASP为I2S工作模式。
(3) tdm-slots = <2> --> 指定通道数。AM335x的手册以更广泛意义的单词slot命名，具体到I2S接口，其含义就是Channel。
(4) serial-dir --> 指定serializer的方向。AM335x的手册中提到每个McASP有16个serializer，但AM335x这款芯片的McAPS只有4个serializer，分别用于AXR0、AXR1、AXR2和ARX3。由于TQ335x中将AXR0作为发送（输出）、ARX1作为接收（输入）且没有ARX2和ARX3，故设置4个serial-dir为1、2、0、0（0表示没有使用，1表示发送，2表示接收）。
(5) tx-num-evt = <1> --> 指定发送FIFO大小，本文设置为1。
(6) rx-num-evt = <1> --> 指定接收FIFO大小，本文设置为1。
至此，就完成了DTS的全部配置，后面我会将完整的DTS文件上传到我的资源。
2. Codec驱动完善
Step1. 修改Codec驱动，使其支持DTS
由于我们在DTS中指定了Codec的compatible为"wlf,wm8960"，而Linux内核自带的WM8960驱动并没有支持新式的DTS模式关联。修改方法很简单，添加i2c_driver的.driver中指定of_match_table即可，修改后的代码片段如下：
[cpp]
view plain
copy
static const struct of_device_id wm8960_of_match[] = {
{ .compatible = "wlf,wm8960", },
{ }
};
MODULE_DEVICE_TABLE(of, wm8960_of_match);
static struct i2c_driver wm8960_i2c_driver = {
.driver = {
.name = "wm8960",
.owner = THIS_MODULE,
.of_match_table = wm8960_of_match,
},
.probe = wm8960_i2c_probe,
.remove = wm8960_i2c_remove,
.id_table = wm8960_i2c_id,
};
Step2. 完善WM8960的初始化信息
默认的WM8960驱动初始化信息不够完整，还需要对WM8960进行额外的初始化，修改后的代码片段如下：
[cpp]
view plain
copy
static int wm8960_probe(struct snd_soc_codec *codec)
{
struct wm8960_priv *wm8960 = snd_soc_codec_get_drvdata(codec);
struct wm8960_data *pdata = dev_get_platdata(codec->dev);
int ret;
wm8960->set_bias_level = wm8960_set_bias_level_out3;
if (!pdata) {
dev_warn(codec->dev, "No platform data supplied\n");
} else {
if (pdata->capless)
wm8960->set_bias_level = wm8960_set_bias_level_capless;
}
ret = wm8960_reset(codec);
if (ret < 0) {
dev_err(codec->dev, "Failed to issue reset\n");
return ret;
}
wm8960->set_bias_level(codec, SND_SOC_BIAS_STANDBY);
/* Latch the update bits */
snd_soc_update_bits(codec, WM8960_LINVOL, 0x100, 0x100);
snd_soc_update_bits(codec, WM8960_RINVOL, 0x100, 0x100);
snd_soc_update_bits(codec, WM8960_LADC, 0x100, 0x100);
snd_soc_update_bits(codec, WM8960_RADC, 0x100, 0x100);
snd_soc_update_bits(codec, WM8960_LDAC, 0x100, 0x100);
snd_soc_update_bits(codec, WM8960_RDAC, 0x100, 0x100);
snd_soc_update_bits(codec, WM8960_LOUT1, 0x100, 0x100);
snd_soc_update_bits(codec, WM8960_ROUT1, 0x100, 0x100);
snd_soc_update_bits(codec, WM8960_LOUT2, 0x100, 0x100);
snd_soc_update_bits(codec, WM8960_ROUT2, 0x100, 0x100);
/* other configuration */
snd_soc_update_bits(codec, WM8960_POWER1, 0x1ea, 0x1ea);
snd_soc_update_bits(codec, WM8960_POWER2, 0x1f8, 0x1f8);
snd_soc_update_bits(codec, WM8960_POWER3, 0xcc, 0xcc);
snd_soc_update_bits(codec, WM8960_LOUTMIX, 0x100, 0x100);
snd_soc_update_bits(codec, WM8960_ROUTMIX, 0x100, 0x100);
snd_soc_update_bits(codec, WM8960_POWER3, 0xc, 0xc);
snd_soc_update_bits(codec, WM8960_LOUT1, 0x7f, 0x7f);
snd_soc_update_bits(codec, WM8960_ROUT1, 0x7f, 0x7f);
snd_soc_update_bits(codec, WM8960_IFACE2, 0x40, 0x40);
snd_soc_update_bits(codec, WM8960_MONOMIX2, 0x120, 0x120);
snd_soc_update_bits(codec, WM8960_LINPATH, 0x1f8, 0x138);
snd_soc_update_bits(codec, WM8960_LINVOL, 0x19f, 0x11f);
snd_soc_update_bits(codec, WM8960_RINVOL, 0x19f, 0x11f);
snd_soc_update_bits(codec, WM8960_LOUT2, 0x1ff, 0x1ff);
snd_soc_update_bits(codec, WM8960_ROUT2, 0x1ff, 0x1ff);
snd_soc_update_bits(codec, WM8960_CLASSD3, 0x1a, 0x12);
snd_soc_update_bits(codec, WM8960_CLASSD1, 0xc0, 0xc0);
snd_soc_add_codec_controls(codec, wm8960_snd_controls,
ARRAY_SIZE(wm8960_snd_controls));
wm8960_add_widgets(codec);
return 0;
}
具体的含义可以参考WM8960的芯片手册，这里我就不一一介绍了。
Step3. 调整WM8960驱动结构
内核中自带的WM8960驱动结构很旧，编写Machine是需要过多的了解Codec芯片内部细节，本文对WM8960的驱动结构进行了调整，可以使Machine忽略Codec的内部细节。
修改的大体内容如下：
(1) 添加set_sysclk函数，接收Machine设置的sysclk时钟频率。具体本文就是DTS中设置的24576000。
(2) 在hw_params中添加BCLK、DACCLK、ADCCLK的配置操作。hw_params可以根据参数和sysclk对以上参数进行设置，放在这里很合适。
(3) 去除函数wm8960_set_dai_clkdiv，并将wm8960_set_dai_pll设置为驱动内部函数，不作为set_pll接口提供给内核驱动（实际上内核驱动也不调用这个函数）。
Step4. 修改WM8960的route信息
根据TQ335x的原理图可知，使用WM8960进行录音或放音时使用的LRCLK是同一个，都是DACCLK，故在snd_soc_dapm_route添加如下两行信息：
[cpp]
view plain
copy
{ "Left DAC", NULL, "Left Input Mixer" },
{ "Right DAC", NULL, "Right Input Mixer" },
这样在录音时也会使能DAC产生LRCLK。
由于调试时间比较长，可能有些修改我没有描述到，完整的wm8960.c文件我会一并上传到我的资源，可以下载参考。
3. 编写Machine驱动
内核代码有个很好的例子就是davinci-evm.c，这是am335x-evm评估板的Machine驱动，该评估采用的Codec并不是WM8960，因此，我们在该文件中添加WM8960信息即可。具体的修改如下：
Step1. 添加compatible信息。修改后的内容如下：
[cpp]
view plain
copy
static const struct of_device_id davinci_evm_dt_ids[] = {
{
.compatible = "ti,tq-evm-audio",
.data = (void *) &evm_dai_wm8960,
},
{
.compatible = "ti,da830-evm-audio",
.data = (void *) &evm_dai_tlv320aic3x,
},
{ /* sentinel */ }
};
Step2. 实现em_dai_wm8960。需要添加如下代码：
[cpp]
view plain
copy
static struct snd_soc_dai_link evm_dai_wm8960 = {
.name = "wm8960",
.stream_name = "wm8960-hifi",
.codec_dai_name = "wm8960-hifi",
.ops = &evm_wm8960_ops,
.init = evm_wm8960_init,
.dai_fmt = SND_SOC_DAIFMT_I2S | SND_SOC_DAIFMT_CBM_CFM |
SND_SOC_DAIFMT_NB_NF,
};
含义：
(1) codec_dai_name = "wm8960-hifi" --> 指定codec设备名称，与wm8960.c中指定的相同即可。
(2) ops --> 指定wm8960的各种操作函数，本文仅实现了hw_params函数。
(3) init --> 指定wm8960的初始化函数，主要是完成dapm相关的初始化。
(4) dai_fmt --> 指定音频的接口方式、主从关系和时钟翻转信息。SND_SOC_DAIFMT_I2S表示音频接口采用I2S协议；SND_SOC_DAIFMT_CBM_CFM表示Codec的BCLK为Master，LRCLK为Master，即wm8960为主，AM335x为从；SND_SOC_DAIFMT_NB_NF表示BCLK和LRCLK都不需要翻转。
Step3.实现evm_wm8960_init
这一部分主要是dapm相关的设置，本人理解也不是非常深刻，直接贴上代码，具体如下：
[cpp]
view plain
copy
static const struct snd_soc_dapm_widget evm_wm8960_dapm_widgets[] = {
SND_SOC_DAPM_SPK("Audio Out1", NULL),
SND_SOC_DAPM_MIC("my Mic", NULL),
SND_SOC_DAPM_MIC("my Line IN", NULL),
};
static const struct snd_kcontrol_new evm_wm8960_controls[] = {
SOC_DAPM_PIN_SWITCH("Audio Out1"),
SOC_DAPM_PIN_SWITCH("my Mic"),
SOC_DAPM_PIN_SWITCH("my Line IN"),
};
static const struct snd_soc_dapm_route evm_wm8960_audio_map[] = {
/* Connections to the ... */
{"Audio Out1", NULL, "HP_L"},
{"Audio Out1", NULL, "HP_R"},
/* Mic */
{"LINPUT1", NULL, "MICB"},
{"MICB", NULL, "my Mic"},
/* Line in */
{"LINPUT3", NULL, "my Line IN"},
{"RINPUT3", NULL, "my Line IN"},
};
static int evm_wm8960_init(struct snd_soc_pcm_runtime *rtd)
{
int err;
struct snd_soc_codec *codec = rtd->codec;
struct snd_soc_dapm_context *dapm = &codec->dapm;
snd_soc_dapm_new_controls(dapm, evm_wm8960_dapm_widgets,
ARRAY_SIZE(evm_wm8960_dapm_widgets ) );
err = snd_soc_add_codec_controls(codec, evm_wm8960_controls,
ARRAY_SIZE(evm_wm8960_controls));
if (err < 0)
return err;
snd_soc_dapm_add_routes(dapm, evm_wm8960_audio_map,
ARRAY_SIZE(evm_wm8960_audio_map));
snd_soc_dapm_enable_pin(dapm, "Audio Out1");
snd_soc_dapm_enable_pin(dapm, "my Mic");
snd_soc_dapm_sync( dapm );
return 0;
}
Step4. 实现evm_wm8960_ops及相关函数，需要添加如下代码：
[cpp]
view plain
copy
static int evm_wm8960_hw_params(struct snd_pcm_substream *substream,
struct snd_pcm_hw_params *params)
{
struct snd_soc_pcm_runtime *rtd = substream->private_data;
struct snd_soc_dai *codec_dai = rtd->codec_dai;
struct snd_soc_dai *cpu_dai = rtd->cpu_dai;
struct snd_soc_card *soc_card = rtd->card;
int ret = 0;
unsigned sysclk = ((struct snd_soc_card_drvdata_davinci *)
snd_soc_card_get_drvdata(soc_card))->sysclk;
/* set the codec system clock */
ret = snd_soc_dai_set_sysclk(codec_dai, 0, sysclk, SND_SOC_CLOCK_IN);
if (ret < 0)
return ret;
/* set the CPU system clock */
ret = snd_soc_dai_set_sysclk(cpu_dai, 0, sysclk, SND_SOC_CLOCK_IN);
if (ret < 0)
return ret;
return 0;
}
static struct snd_soc_ops evm_wm8960_ops = {
.startup = evm_startup,
.shutdown = evm_shutdown,
.hw_params = evm_wm8960_hw_params,
};
至此，就完成了代码移植的全部工作，修改涉及到的三个文件是：tq335x.dts、davinci-evm.c和wm8960.c，修改后的这三个文件我会上传到我的资源，如有需要，请去我的资源中下载。
4. 配置内核
完成了代码的移植工作之后还需要对内核进一步配置。默认的内核将ALSA作为module加载，本文将编译进内核。具体步骤如下：
Step1. 修改sound/soc/codecs/Kconfig，添加wm8960编译选项，修改后的内容如下：
[cpp]
view plain
copy
config SND_SOC_WM8960
tristate "Wolfson Microelectronics WM8960 CODEC"
depends on I2C && INPUT
Step2. 通过menuconfig配置内核
执行指令：
[cpp]
view plain
copy
make ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- menuconfig
进行如下修改：
[cpp]
view plain
copy
Device Drivers --->
<*> Sound card support --->
<*> Advanced Linux Sound Architecture --->
<*> ALSA for SoC audio support --->
<*> SoC Audio for Texas Instruments chips using eDMA (AM33XX/43XX)
-*- Multichannel Audio Serial Port (McASP) support
<*> SoC Audio for the AM33XX chip based boards
CODEC drivers --->
<*> Wolfson Microelectronics WM8960 CODEC
重新编译内核：
[cpp]
view plain
copy
make ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- -j8
5. 效果
将编译后的内核文件zImage和tq335x.dtb文件拷贝SD卡并启动开发板，按任意键进入uboot命令模式，输入如下指令：
[cpp]
view plain
copy
load mmc 0:1 0x88000000 /boot/tq335x.dtb
load mmc 0:1 0x82000000 /boot/zImage
bootz 0x82000000 - 0x88000000
通过上面的三条指令可以启动内核，完整的Log信息如下：
[cpp]
view plain
copy
Starting kernel ...
[ 0.000000] Booting Linux on physical CPU 0x0
[ 0.000000] Linux version 3.17.2 (lilianrong@smarter) (gcc version 4.7.3 (Ubuntu/Linaro 4.7.3-12ubuntu1) ) #68 SMP Sat Dec 20 00:03:09 CST 2014
[ 0.000000] CPU: ARMv7 Processor [413fc082] revision 2 (ARMv7), cr=10c5387d
[ 0.000000] CPU: PIPT / VIPT nonaliasing data cache, VIPT aliasing instruction cache
[ 0.000000] Machine model: TI AM335x EVM
[ 0.000000] cma: Reserved 16 MiB at 9e800000
[ 0.000000] Memory policy: Data cache writeback
[ 0.000000] HighMem zone: 1048574 pages exceeds freesize 0
[ 0.000000] CPU: All CPU(s) started in SVC mode.
[ 0.000000] AM335X ES2.1 (sgx neon )
[ 0.000000] PERCPU: Embedded 9 pages/cpu @dfa99000 s14336 r8192 d14336 u36864
[ 0.000000] Built 1 zonelists in Zone order, mobility grouping on. Total pages: 129792
[ 0.000000] Kernel command line: console=ttyO0,115200n8 root=/dev/mmcblk0p2 rw rootfstype=ext3 rootwait
[ 0.000000] PID hash table entries: 2048 (order: 1, 8192 bytes)
[ 0.000000] Dentry cache hash table entries: 65536 (order: 6, 262144 bytes)
[ 0.000000] Inode-cache hash table entries: 32768 (order: 5, 131072 bytes)
[ 0.000000] Memory: 484124K/523264K available (6070K kernel code, 666K rwdata, 2444K rodata, 410K init, 8214K bss, 39140K reserved, 0K highmem)
[ 0.000000] Virtual kernel memory layout:
[ 0.000000] vector : 0xffff0000 - 0xffff1000 ( 4 kB)
[ 0.000000] fixmap : 0xffc00000 - 0xffe00000 (2048 kB)
[ 0.000000] vmalloc : 0xe0800000 - 0xff000000 ( 488 MB)
[ 0.000000] lowmem : 0xc0000000 - 0xe0000000 ( 512 MB)
[ 0.000000] pkmap : 0xbfe00000 - 0xc0000000 ( 2 MB)
[ 0.000000] modules : 0xbf000000 - 0xbfe00000 ( 14 MB)
[ 0.000000] .text : 0xc0008000 - 0xc0858bc0 (8515 kB)
[ 0.000000] .init : 0xc0859000 - 0xc08bf800 ( 410 kB)
[ 0.000000] .data : 0xc08c0000 - 0xc0966b50 ( 667 kB)
[ 0.000000] .bss : 0xc0966b50 - 0xc116c6e0 (8215 kB)
[ 0.000000] Hierarchical RCU implementation.
[ 0.000000] RCU restricting CPUs from NR_CPUS=2 to nr_cpu_ids=1.
[ 0.000000] RCU: Adjusting geometry for rcu_fanout_leaf=16, nr_cpu_ids=1
[ 0.000000] NR_IRQS:16 nr_irqs:16 16
[ 0.000000] IRQ: Found an INTC at 0xfa200000 (revision 5.0) with 128 interrupts
[ 0.000000] Total of 128 interrupts on 1 active controller
[ 0.000000] OMAP clockevent source: timer2 at 24000000 Hz
[ 0.000015] sched_clock: 32 bits at 24MHz, resolution 41ns, wraps every 178956969942ns
[ 0.000061] OMAP clocksource: timer1 at 24000000 Hz
[ 0.000798] Console: colour dummy device 80x30
[ 0.000849] Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar
[ 0.000858] ... MAX_LOCKDEP_SUBCLASSES: 8
[ 0.000865] ... MAX_LOCK_DEPTH: 48
[ 0.000873] ... MAX_LOCKDEP_KEYS: 8191
[ 0.000880] ... CLASSHASH_SIZE: 4096
[ 0.000887] ... MAX_LOCKDEP_ENTRIES: 32768
[ 0.000894] ... MAX_LOCKDEP_CHAINS: 65536
[ 0.000901] ... CHAINHASH_SIZE: 32768
[ 0.000909] memory used by lock dependency info: 5167 kB
[ 0.000916] per task-struct memory footprint: 1152 bytes
[ 0.000956] Calibrating delay loop... 996.14 BogoMIPS (lpj=4980736)
[ 0.079039] pid_max: default: 32768 minimum: 301
[ 0.079431] Security Framework initialized
[ 0.079555] Mount-cache hash table entries: 1024 (order: 0, 4096 bytes)
[ 0.079568] Mountpoint-cache hash table entries: 1024 (order: 0, 4096 bytes)
[ 0.081736] CPU: Testing write buffer coherency: ok
[ 0.082916] CPU0: thread -1, cpu 0, socket -1, mpidr 0
[ 0.083033] Setting up static identity map for 0x805bf4f0 - 0x805bf560
[ 0.086259] Brought up 1 CPUs
[ 0.086278] SMP: Total of 1 processors activated.
[ 0.086288] CPU: All CPU(s) started in SVC mode.
[ 0.088875] devtmpfs: initialized
[ 0.097689] VFP support v0.3: implementor 41 architecture 3 part 30 variant c rev 3
[ 0.133508] omap_hwmod: tptc0 using broken dt data from edma
[ 0.133865] omap_hwmod: tptc1 using broken dt data from edma
[ 0.134203] omap_hwmod: tptc2 using broken dt data from edma
[ 0.142102] omap_hwmod: debugss: _wait_target_disable failed
[ 0.200093] pinctrl core: initialized pinctrl subsystem
[ 0.202608] regulator-dummy: no parameters
[ 0.232298] NET: Registered protocol family 16
[ 0.240800] DMA: preallocated 256 KiB pool for atomic coherent allocations
[ 0.243054] cpuidle: using governor ladder
[ 0.243083] cpuidle: using governor menu
[ 0.255025] OMAP GPIO hardware version 0.1
[ 0.270226] omap-gpmc 50000000.gpmc: could not find pctldev for node /pinmux@44e10800/nandflash_pins_s0, deferring probe
[ 0.270268] platform 50000000.gpmc: Driver omap-gpmc requests probe deferral
[ 0.274762] hw-breakpoint: debug architecture 0x4 unsupported.
[ 0.319722] edma-dma-engine edma-dma-engine.0: TI EDMA DMA engine driver
[ 0.321054] vbat: 5000 mV
[ 0.321851] lis3_reg: no parameters
[ 0.325260] SCSI subsystem initialized
[ 0.326060] usbcore: registered new interface driver usbfs
[ 0.326235] usbcore: registered new interface driver hub
[ 0.330180] usbcore: registered new device driver usb
[ 0.331021] omap_i2c 44e0b000.i2c: could not find pctldev for node /pinmux@44e10800/pinmux_i2c0_pins, deferring probe
[ 0.331059] platform 44e0b000.i2c: Driver omap_i2c requests probe deferral
[ 0.331115] omap_i2c 4802a000.i2c: could not find pctldev for node /pinmux@44e10800/pinmux_i2c1_pins, deferring probe
[ 0.331139] platform 4802a000.i2c: Driver omap_i2c requests probe deferral
[ 0.332318] Advanced Linux Sound Architecture Driver Initialized.
[ 0.335684] Switched to clocksource timer1
[ 0.486994] NET: Registered protocol family 2
[ 0.488860] TCP established hash table entries: 4096 (order: 2, 16384 bytes)
[ 0.489040] TCP bind hash table entries: 4096 (order: 5, 147456 bytes)
[ 0.490403] TCP: Hash tables configured (established 4096 bind 4096)
[ 0.490593] TCP: reno registered
[ 0.490617] UDP hash table entries: 256 (order: 2, 20480 bytes)
[ 0.490807] UDP-Lite hash table entries: 256 (order: 2, 20480 bytes)
[ 0.491827] NET: Registered protocol family 1
[ 0.493704] RPC: Registered named UNIX socket transport module.
[ 0.493729] RPC: Registered udp transport module.
[ 0.493738] RPC: Registered tcp transport module.
[ 0.493747] RPC: Registered tcp NFSv4.1 backchannel transport module.
[ 0.495022] hw perfevents: enabled with armv7_cortex_a8 PMU driver, 5 counters available
[ 0.499438] futex hash table entries: 256 (order: 2, 16384 bytes)
[ 0.504727] VFS: Disk quotas dquot_6.5.2
[ 0.504882] Dquot-cache hash table entries: 1024 (order 0, 4096 bytes)
[ 0.507359] NFS: Registering the id_resolver key type
[ 0.507727] Key type id_resolver registered
[ 0.507743] Key type id_legacy registered
[ 0.507886] jffs2: version 2.2. (NAND) (SUMMARY) 漏 2001-2006 Red Hat, Inc.
[ 0.508320] msgmni has been set to 977
[ 0.513238] io scheduler noop registered
[ 0.513269] io scheduler deadline registered
[ 0.513341] io scheduler cfq registered (default)
[ 0.515815] pinctrl-single 44e10800.pinmux: 142 pins at pa f9e10800 size 568
[ 0.520975] backlight supply power not found, using dummy regulator
[ 0.524309] Serial: 8250/16550 driver, 4 ports, IRQ sharing enabled
[ 0.530939] omap_uart 44e09000.serial: no wakeirq for uart0
[ 0.531575] 44e09000.serial: ttyO0 at MMIO 0x44e09000 (irq = 88, base_baud = 3000000) is a OMAP UART0
[ 1.231857] console [ttyO0] enabled
[ 1.241315] omap_rng 48310000.rng: OMAP Random Number Generator ver. 20
[ 1.248987] [drm] Initialized drm 1.1.0 20060810
[ 1.261218] [drm] Supports vblank timestamp caching Rev 2 (21.10.2013).
[ 1.268316] [drm] No driver support for vblank timestamp query.
[ 1.320991] Console: switching to colour frame buffer device 100x30
[ 1.332042] tilcdc 4830e000.lcdc: fb0: frame buffer device
[ 1.337919] tilcdc 4830e000.lcdc: registered panic notifier
[ 1.343814] [drm] Initialized tilcdc 1.0.0 20121205 on minor 0
[ 1.380804] brd: module loaded
[ 1.398539] loop: module loaded
[ 1.404724] mtdoops: mtd device (mtddev=name/number) must be supplied
[ 1.414737] usbcore: registered new interface driver asix
[ 1.420619] usbcore: registered new interface driver ax88179_178a
[ 1.427154] usbcore: registered new interface driver cdc_ether
[ 1.433416] usbcore: registered new interface driver smsc95xx
[ 1.439572] usbcore: registered new interface driver net1080
[ 1.445625] usbcore: registered new interface driver cdc_subset
[ 1.451932] usbcore: registered new interface driver zaurus
[ 1.457997] usbcore: registered new interface driver cdc_ncm
[ 1.465136] usbcore: registered new interface driver cdc_wdm
[ 1.471412] usbcore: registered new interface driver usb-storage
[ 1.477942] usbcore: registered new interface driver usbtest
[ 1.486105] mousedev: PS/2 mouse device common for all mice
[ 1.496690] omap_rtc 44e3e000.rtc: rtc core: registered 44e3e000.rtc as rtc0
[ 1.504827] i2c /dev entries driver
[ 1.508655] Driver for 1-wire Dallas network protocol.
[ 1.517293] omap_wdt: OMAP Watchdog Timer Rev 0x01: initial timeout 60 sec
[ 1.527282] omap_hsmmc 48060000.mmc: unable to get vmmc regulator -517
[ 1.534612] platform 48060000.mmc: Driver omap_hsmmc requests probe deferral
[ 1.544215] ledtrig-cpu: registered to indicate activity on CPUs
[ 1.551195] usbcore: registered new interface driver usbhid
[ 1.557065] usbhid: USB HID core driver
[ 1.575960] davinci_evm sound: ASoC: CODEC (null) not registered
[ 1.582524] davinci_evm sound: snd_soc_register_card failed (-517)
[ 1.589121] platform sound: Driver davinci_evm requests probe deferral
[ 1.596830] oprofile: using arm/armv7
[ 1.601311] TCP: cubic registered
[ 1.604789] Initializing XFRM netlink socket
[ 1.609445] NET: Registered protocol family 17
[ 1.614179] NET: Registered protocol family 15
[ 1.619196] Key type dns_resolver registered
[ 1.623867] omap_voltage_late_init: Voltage driver support not added
[ 1.630565] sr_dev_init: No voltage domain specified for smartreflex0. Cannot initialize
[ 1.639038] sr_dev_init: No voltage domain specified for smartreflex1. Cannot initialize
[ 1.648614] ThumbEE CPU extension supported.
[ 1.653130] Registering SWP/SWPB emulation handler
[ 1.658211] SmartReflex Class3 initialized
[ 1.667886] omap-gpmc 50000000.gpmc: GPMC revision 6.0
[ 1.674877] nand: device found, Manufacturer ID: 0xec, Chip ID: 0xd3
[ 1.681647] nand: Samsung NAND 1GiB 3,3V 8-bit
[ 1.686312] nand: 1024MiB, SLC, page size: 2048, OOB size: 64
[ 1.692312] nand: error: CONFIG_MTD_NAND_OMAP_BCH not enabled
[ 1.698428] omap2-nand: probe of omap2-nand.0 failed with error -22
[ 1.790962] tps65910 0-002d: No interrupt support, no core IRQ
[ 1.807488] vrtc: 1800 mV
[ 1.810865] vrtc: supplied by vbat
[ 1.818190] vio: at 1500 mV
[ 1.821460] vio: supplied by vbat
[ 1.828397] vdd_mpu: 912 <--> 1312 mV at 1325 mV
[ 1.833532] vdd_mpu: supplied by vbat
[ 1.840598] vdd_core: 912 <--> 1150 mV at 1137 mV
[ 1.845924] vdd_core: supplied by vbat
[ 1.852537] vdd3: 5000 mV
[ 1.858001] vdig1: at 1800 mV
[ 1.861420] vdig1: supplied by vbat
[ 1.867904] vdig2: at 1800 mV
[ 1.871302] vdig2: supplied by vbat
[ 1.878529] vpll: at 1800 mV
[ 1.881866] vpll: supplied by vbat
[ 1.888426] vdac: at 1800 mV
[ 1.891747] vdac: supplied by vbat
[ 1.898169] vaux1: at 1800 mV
[ 1.901568] vaux1: supplied by vbat
[ 1.908027] vaux2: at 3300 mV
[ 1.911421] vaux2: supplied by vbat
[ 1.917833] vaux33: at 3300 mV
[ 1.921323] vaux33: supplied by vbat
[ 1.927806] vmmc: 1800 <--> 3300 mV at 3300 mV
[ 1.932761] vmmc: supplied by vbat
[ 1.938842] vbb: at 3000 mV
[ 1.942302] vbb: supplied by vbat
[ 1.949841] omap_i2c 44e0b000.i2c: bus 0 rev0.11 at 400 kHz
[ 1.963667] omap_i2c 4802a000.i2c: bus 1 rev0.11 at 100 kHz
[ 2.007363] wm8960 0-001a: No platform data supplied
[ 2.084399] mmc0: host does not support reading read-only switch. assuming write-enable.
[ 2.095817] mmc0: new high speed SDHC card at address aaaa
[ 2.104312] mmcblk0: mmc0:aaaa SL16G 14.8 GiB
[ 2.116665] mmcblk0: p1 p2
[ 2.131506] davinci_evm sound: wm8960-hifi <-> 4803c000.mcasp mapping ok
[ 2.215823] davinci_mdio 4a101000.mdio: davinci mdio revision 1.6
[ 2.222212] davinci_mdio 4a101000.mdio: detected phy mask ffffffde
[ 2.232273] libphy: 4a101000.mdio: probed
[ 2.236597] davinci_mdio 4a101000.mdio: phy[0]: device 4a101000.mdio:00, driver unknown
[ 2.244957] davinci_mdio 4a101000.mdio: phy[5]: device 4a101000.mdio:05, driver unknown
[ 2.254567] cpsw 4a100000.ethernet: Detected MACID = c4:ed:ba:88:b5:e4
[ 2.266507] input: gpio_keyad@0 as /devices/gpio_keyad@0/input/input0
[ 2.276227] omap_rtc 44e3e000.rtc: setting system clock to 2000-01-01 00:00:00 UTC (946684800)
[ 2.285247] sr_init: No PMIC hook to init smartreflex
[ 2.290884] sr_init: platform driver register failed for SR
[ 2.313832] lis3_reg: disabling
[ 2.317496] ALSA device list:
[ 2.320598] #0: AM335x-EVM
[ 2.434398] kjournald starting. Commit interval 5 seconds
[ 2.444085] EXT3-fs (mmcblk0p2): using internal journal
[ 2.452049] EXT3-fs (mmcblk0p2): recovery complete
[ 2.457123] EXT3-fs (mmcblk0p2): mounted filesystem with ordered data mode
[ 2.464445] VFS: Mounted root (ext3 filesystem) on device 179:2.
[ 2.474111] devtmpfs: mounted
[ 2.478057] Freeing unused kernel memory: 408K (c0859000 - c08bf000)
----------mount all..........
----------Starting mdev......
Please press Enter to activate this console.
@tq335x #
从Log信息中很容易看到ALSA device list已经出现了AM335x-EVM项。到这里TQ335x已经能够识别到声卡了。
6. 测试
测试ALSA声卡驱动的常用方法是移植alsa-lib和alsa-utils，使用alsa-utils提供的arecord来测试声卡的录音，aplay来测试播放。alsa-lib和alsa-utils的移植教程有很多，这里我就不多讲了（如果有不明白这块的可以留言）。
录音测试：
[cpp]
view plain
copy
arecord -f cd test.wav
播放测试：
[cpp]
view plain
copy
aplay test.wav
播放时就可以听到之前录制的声音的。
7. 总结
调试声卡驱动大约进行了三周，也算是略有心得。
(1) 必要的工具：我调试的时候手头上工具不够齐全。我是在家里调试的，没有示波器，也就无法测量BCLK和LRCLK时钟，调试了很久都不知道WM8960到底有没有工作，因此，必要的工具可以有效的提高调试效率。
(2) 先调试放音，wm8960放音再调试录音。放音可以很容易检测效果，录音则没有方便的检测手段。同时，放音的配置比录音要简单些，可以有效检测驱动部分是否存在问题。
以上是完整的WM8960驱动移植过程，如果疑问欢迎留言讨论。
本文作者：girlkoo
本文连接：/article/1329492.html
ASoC是对ALSA驱动架构的进一步封装。ASoC将ALSA驱动中的各模块抽象为三部分：Platform、Codec和Machine。Platform主要是平台硬件驱动，包括SoC的IIS模块、DMA等，在本文中就是指AM335x的McASP模块及AM335x用于音频读写操作的EDMA。Codec是编解码芯片驱动，在本文中就是WM8960。Machine是用来描述单板音频系统连接关系的驱动，在本文中其作用是将WM8960与McASP绑定起来，注册声卡设备节点。由于3.17版本的内核已经带有TI维护的McASP驱动和Wolf公司维护的WM8960驱动，因此，原理上讲，我们只需要编写Machine部分，建立WM8960与McASP的连接关系即可。不幸的是Wolf对WM8960的维护不是太完善，还需要我们进一步修改。下面我们来看下WM8960在TQ335x上的移植方法。
1. 在DTS中添加声卡信息
Step1. 完善sound信息
在DTS有一个节点名为sound，该节点用来描述单板上声卡设备信息，修改后的内容如下：
[cpp]
view plain
copy
sound {
compatible = "ti,tq-evm-audio";
ti,model = "AM335x-EVM";
ti,audio-codec = <&wm8960>;
ti,mcasp-controller = <&mcasp1>;
ti,codec-clock-rate = <24576000>;
ti,audio-routing =
"Headphone Jack", "HP_L",
"Headphone Jack", "HP_R",
"LINPUT1", "Line In";
};
含义解释：
(1) compatible = "ti,tq-evm-audio" --> 指定声卡兼容的设备，与Machine驱动中的compatible匹配。
(2) ti,model = "AM335x-EVM" --> 声卡的名称，原则上讲可以随意指定，但最好具有一定的可读性，这里没有修改。
(3) ti,audio-codec = <&wm8960> --> 指定单板使用的Codec，具体的Codec信息由其指向的节点wm8960描述。
(4) ti,mcasp-controller = <&mcasp1> --> 指定单板使用的Codec连接到AM335x的McASP1上，McASP1的具体信息由其指向的节点mcasp1描述。
(5) ti,codec-clock-rate = <24576000> --> 指定Codec的MCLK时钟频率，单位是HZ。TQ335x的Codec使用24.576MHZ的有源晶振提供MCLK，故设置为24576000。
(6) ti,audio-routing --> DAPM信息描述，用来指定Codec与McASP的连接关系。此处若不设置，则需要在Machine驱动中进行设置。本文在这里做了修改。
Step2. 完善Codec信息
通过阅读TQ335x的原理图可知，WM8960的控制端口连接到了AM335x的I2C0端口上，因此，可以i2c0节点内添加如下信息（类似上篇文章中触摸设备驱动节点）：
[cpp]
view plain
copy
wm8960: wm8960@1a {
compatible = "wlf,wm8960";
reg = <0x1a>;
};
含义解释：
(1) compatible = "wlf,wm8960" --> 指定Codec兼容设备，与Codec驱动中的compatible匹配。
(2) reg = <0x1a> --> WM8960的I2C地址是1A，故设置为0x1a。
Step3. 完善Platform信息
AM335x的Platform信息主要指McASP和EMDA设置信息。由于默认的DTS已经配置好了McASP及EDMA的大部分信息，需要我们配置的是McASP的pinmux和i2s信息。
(1) 修改pinmux信息需要具体参考TQ335x的原理图，下面是根据原理图中的引脚连接方式修改的pinmux信息，如果有啥不懂的可以留言讨论：
[cpp]
view plain
copy
am335x_evm_audio_pins: am335x_evm_audio_pins {
pinctrl-single,pins = <
0x1A0 (PIN_INPUT_PULLDOWN | MUX_MODE3) /* mcasp0_aclkr.mcasp1_aclkx */
0x1A4 (PIN_INPUT_PULLDOWN | MUX_MODE3) /* mcasp0_fsr.mcasp1_fsx */
0x1A8 (PIN_OUTPUT_PULLDOWN | MUX_MODE3) /* mcasp0_axr1.mcasp1_axr0 */
0x1AC (PIN_INPUT_PULLDOWN | MUX_MODE3) /* mcasp0_ahclkx.mcasp1_axr1 */
>;
};
(2) i2s的配置信息需要在mcasp1节点中修改，具体的修改如下：
[cpp]
view plain
copy
&mcasp1 {
pinctrl-names = "default";
pinctrl-0 = <&am335x_evm_audio_pins>;
status = "okay";
op-mode = <0>; /* MCASP_IIS_MODE */
tdm-slots = <2>;
/* 4 serializers */
serial-dir = < /* 0: INACTIVE, 1: TX, 2: RX */
1 2 0 0
>;
tx-num-evt = <1>;
rx-num-evt = <1>;
};
含义：
(1) pinctrl-0 = <&am335x_evm_audio_pins> --> 指定mcasp1的pinmux信息。
(2) op-mode = <0> --> 指定McASP为I2S工作模式。
(3) tdm-slots = <2> --> 指定通道数。AM335x的手册以更广泛意义的单词slot命名，具体到I2S接口，其含义就是Channel。
(4) serial-dir --> 指定serializer的方向。AM335x的手册中提到每个McASP有16个serializer，但AM335x这款芯片的McAPS只有4个serializer，分别用于AXR0、AXR1、AXR2和ARX3。由于TQ335x中将AXR0作为发送（输出）、ARX1作为接收（输入）且没有ARX2和ARX3，故设置4个serial-dir为1、2、0、0（0表示没有使用，1表示发送，2表示接收）。
(5) tx-num-evt = <1> --> 指定发送FIFO大小，本文设置为1。
(6) rx-num-evt = <1> --> 指定接收FIFO大小，本文设置为1。
至此，就完成了DTS的全部配置，后面我会将完整的DTS文件上传到我的资源。
2. Codec驱动完善
Step1. 修改Codec驱动，使其支持DTS
由于我们在DTS中指定了Codec的compatible为"wlf,wm8960"，而Linux内核自带的WM8960驱动并没有支持新式的DTS模式关联。修改方法很简单，添加i2c_driver的.driver中指定of_match_table即可，修改后的代码片段如下：
[cpp]
view plain
copy
static const struct of_device_id wm8960_of_match[] = {
{ .compatible = "wlf,wm8960", },
{ }
};
MODULE_DEVICE_TABLE(of, wm8960_of_match);
static struct i2c_driver wm8960_i2c_driver = {
.driver = {
.name = "wm8960",
.owner = THIS_MODULE,
.of_match_table = wm8960_of_match,
},
.probe = wm8960_i2c_probe,
.remove = wm8960_i2c_remove,
.id_table = wm8960_i2c_id,
};
Step2. 完善WM8960的初始化信息
默认的WM8960驱动初始化信息不够完整，还需要对WM8960进行额外的初始化，修改后的代码片段如下：
[cpp]
view plain
copy
static int wm8960_probe(struct snd_soc_codec *codec)
{
struct wm8960_priv *wm8960 = snd_soc_codec_get_drvdata(codec);
struct wm8960_data *pdata = dev_get_platdata(codec->dev);
int ret;
wm8960->set_bias_level = wm8960_set_bias_level_out3;
if (!pdata) {
dev_warn(codec->dev, "No platform data supplied\n");
} else {
if (pdata->capless)
wm8960->set_bias_level = wm8960_set_bias_level_capless;
}
ret = wm8960_reset(codec);
if (ret < 0) {
dev_err(codec->dev, "Failed to issue reset\n");
return ret;
}
wm8960->set_bias_level(codec, SND_SOC_BIAS_STANDBY);
/* Latch the update bits */
snd_soc_update_bits(codec, WM8960_LINVOL, 0x100, 0x100);
snd_soc_update_bits(codec, WM8960_RINVOL, 0x100, 0x100);
snd_soc_update_bits(codec, WM8960_LADC, 0x100, 0x100);
snd_soc_update_bits(codec, WM8960_RADC, 0x100, 0x100);
snd_soc_update_bits(codec, WM8960_LDAC, 0x100, 0x100);
snd_soc_update_bits(codec, WM8960_RDAC, 0x100, 0x100);
snd_soc_update_bits(codec, WM8960_LOUT1, 0x100, 0x100);
snd_soc_update_bits(codec, WM8960_ROUT1, 0x100, 0x100);
snd_soc_update_bits(codec, WM8960_LOUT2, 0x100, 0x100);
snd_soc_update_bits(codec, WM8960_ROUT2, 0x100, 0x100);
/* other configuration */
snd_soc_update_bits(codec, WM8960_POWER1, 0x1ea, 0x1ea);
snd_soc_update_bits(codec, WM8960_POWER2, 0x1f8, 0x1f8);
snd_soc_update_bits(codec, WM8960_POWER3, 0xcc, 0xcc);
snd_soc_update_bits(codec, WM8960_LOUTMIX, 0x100, 0x100);
snd_soc_update_bits(codec, WM8960_ROUTMIX, 0x100, 0x100);
snd_soc_update_bits(codec, WM8960_POWER3, 0xc, 0xc);
snd_soc_update_bits(codec, WM8960_LOUT1, 0x7f, 0x7f);
snd_soc_update_bits(codec, WM8960_ROUT1, 0x7f, 0x7f);
snd_soc_update_bits(codec, WM8960_IFACE2, 0x40, 0x40);
snd_soc_update_bits(codec, WM8960_MONOMIX2, 0x120, 0x120);
snd_soc_update_bits(codec, WM8960_LINPATH, 0x1f8, 0x138);
snd_soc_update_bits(codec, WM8960_LINVOL, 0x19f, 0x11f);
snd_soc_update_bits(codec, WM8960_RINVOL, 0x19f, 0x11f);
snd_soc_update_bits(codec, WM8960_LOUT2, 0x1ff, 0x1ff);
snd_soc_update_bits(codec, WM8960_ROUT2, 0x1ff, 0x1ff);
snd_soc_update_bits(codec, WM8960_CLASSD3, 0x1a, 0x12);
snd_soc_update_bits(codec, WM8960_CLASSD1, 0xc0, 0xc0);
snd_soc_add_codec_controls(codec, wm8960_snd_controls,
ARRAY_SIZE(wm8960_snd_controls));
wm8960_add_widgets(codec);
return 0;
}
具体的含义可以参考WM8960的芯片手册，这里我就不一一介绍了。
Step3. 调整WM8960驱动结构
内核中自带的WM8960驱动结构很旧，编写Machine是需要过多的了解Codec芯片内部细节，本文对WM8960的驱动结构进行了调整，可以使Machine忽略Codec的内部细节。
修改的大体内容如下：
(1) 添加set_sysclk函数，接收Machine设置的sysclk时钟频率。具体本文就是DTS中设置的24576000。
(2) 在hw_params中添加BCLK、DACCLK、ADCCLK的配置操作。hw_params可以根据参数和sysclk对以上参数进行设置，放在这里很合适。
(3) 去除函数wm8960_set_dai_clkdiv，并将wm8960_set_dai_pll设置为驱动内部函数，不作为set_pll接口提供给内核驱动（实际上内核驱动也不调用这个函数）。
Step4. 修改WM8960的route信息
根据TQ335x的原理图可知，使用WM8960进行录音或放音时使用的LRCLK是同一个，都是DACCLK，故在snd_soc_dapm_route添加如下两行信息：
[cpp]
view plain
copy
{ "Left DAC", NULL, "Left Input Mixer" },
{ "Right DAC", NULL, "Right Input Mixer" },
这样在录音时也会使能DAC产生LRCLK。
由于调试时间比较长，可能有些修改我没有描述到，完整的wm8960.c文件我会一并上传到我的资源，可以下载参考。
3. 编写Machine驱动
内核代码有个很好的例子就是davinci-evm.c，这是am335x-evm评估板的Machine驱动，该评估采用的Codec并不是WM8960，因此，我们在该文件中添加WM8960信息即可。具体的修改如下：
Step1. 添加compatible信息。修改后的内容如下：
[cpp]
view plain
copy
static const struct of_device_id davinci_evm_dt_ids[] = {
{
.compatible = "ti,tq-evm-audio",
.data = (void *) &evm_dai_wm8960,
},
{
.compatible = "ti,da830-evm-audio",
.data = (void *) &evm_dai_tlv320aic3x,
},
{ /* sentinel */ }
};
Step2. 实现em_dai_wm8960。需要添加如下代码：
[cpp]
view plain
copy
static struct snd_soc_dai_link evm_dai_wm8960 = {
.name = "wm8960",
.stream_name = "wm8960-hifi",
.codec_dai_name = "wm8960-hifi",
.ops = &evm_wm8960_ops,
.init = evm_wm8960_init,
.dai_fmt = SND_SOC_DAIFMT_I2S | SND_SOC_DAIFMT_CBM_CFM |
SND_SOC_DAIFMT_NB_NF,
};
含义：
(1) codec_dai_name = "wm8960-hifi" --> 指定codec设备名称，与wm8960.c中指定的相同即可。
(2) ops --> 指定wm8960的各种操作函数，本文仅实现了hw_params函数。
(3) init --> 指定wm8960的初始化函数，主要是完成dapm相关的初始化。
(4) dai_fmt --> 指定音频的接口方式、主从关系和时钟翻转信息。SND_SOC_DAIFMT_I2S表示音频接口采用I2S协议；SND_SOC_DAIFMT_CBM_CFM表示Codec的BCLK为Master，LRCLK为Master，即wm8960为主，AM335x为从；SND_SOC_DAIFMT_NB_NF表示BCLK和LRCLK都不需要翻转。
Step3.实现evm_wm8960_init
这一部分主要是dapm相关的设置，本人理解也不是非常深刻，直接贴上代码，具体如下：
[cpp]
view plain
copy
static const struct snd_soc_dapm_widget evm_wm8960_dapm_widgets[] = {
SND_SOC_DAPM_SPK("Audio Out1", NULL),
SND_SOC_DAPM_MIC("my Mic", NULL),
SND_SOC_DAPM_MIC("my Line IN", NULL),
};
static const struct snd_kcontrol_new evm_wm8960_controls[] = {
SOC_DAPM_PIN_SWITCH("Audio Out1"),
SOC_DAPM_PIN_SWITCH("my Mic"),
SOC_DAPM_PIN_SWITCH("my Line IN"),
};
static const struct snd_soc_dapm_route evm_wm8960_audio_map[] = {
/* Connections to the ... */
{"Audio Out1", NULL, "HP_L"},
{"Audio Out1", NULL, "HP_R"},
/* Mic */
{"LINPUT1", NULL, "MICB"},
{"MICB", NULL, "my Mic"},
/* Line in */
{"LINPUT3", NULL, "my Line IN"},
{"RINPUT3", NULL, "my Line IN"},
};
static int evm_wm8960_init(struct snd_soc_pcm_runtime *rtd)
{
int err;
struct snd_soc_codec *codec = rtd->codec;
struct snd_soc_dapm_context *dapm = &codec->dapm;
snd_soc_dapm_new_controls(dapm, evm_wm8960_dapm_widgets,
ARRAY_SIZE(evm_wm8960_dapm_widgets ) );
err = snd_soc_add_codec_controls(codec, evm_wm8960_controls,
ARRAY_SIZE(evm_wm8960_controls));
if (err < 0)
return err;
snd_soc_dapm_add_routes(dapm, evm_wm8960_audio_map,
ARRAY_SIZE(evm_wm8960_audio_map));
snd_soc_dapm_enable_pin(dapm, "Audio Out1");
snd_soc_dapm_enable_pin(dapm, "my Mic");
snd_soc_dapm_sync( dapm );
return 0;
}
Step4. 实现evm_wm8960_ops及相关函数，需要添加如下代码：
[cpp]
view plain
copy
static int evm_wm8960_hw_params(struct snd_pcm_substream *substream,
struct snd_pcm_hw_params *params)
{
struct snd_soc_pcm_runtime *rtd = substream->private_data;
struct snd_soc_dai *codec_dai = rtd->codec_dai;
struct snd_soc_dai *cpu_dai = rtd->cpu_dai;
struct snd_soc_card *soc_card = rtd->card;
int ret = 0;
unsigned sysclk = ((struct snd_soc_card_drvdata_davinci *)
snd_soc_card_get_drvdata(soc_card))->sysclk;
/* set the codec system clock */
ret = snd_soc_dai_set_sysclk(codec_dai, 0, sysclk, SND_SOC_CLOCK_IN);
if (ret < 0)
return ret;
/* set the CPU system clock */
ret = snd_soc_dai_set_sysclk(cpu_dai, 0, sysclk, SND_SOC_CLOCK_IN);
if (ret < 0)
return ret;
return 0;
}
static struct snd_soc_ops evm_wm8960_ops = {
.startup = evm_startup,
.shutdown = evm_shutdown,
.hw_params = evm_wm8960_hw_params,
};
至此，就完成了代码移植的全部工作，修改涉及到的三个文件是：tq335x.dts、davinci-evm.c和wm8960.c，修改后的这三个文件我会上传到我的资源，如有需要，请去我的资源中下载。
4. 配置内核
完成了代码的移植工作之后还需要对内核进一步配置。默认的内核将ALSA作为module加载，本文将编译进内核。具体步骤如下：
Step1. 修改sound/soc/codecs/Kconfig，添加wm8960编译选项，修改后的内容如下：
[cpp]
view plain
copy
config SND_SOC_WM8960
tristate "Wolfson Microelectronics WM8960 CODEC"
depends on I2C && INPUT
Step2. 通过menuconfig配置内核
执行指令：
[cpp]
view plain
copy
make ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- menuconfig
进行如下修改：
[cpp]
view plain
copy
Device Drivers --->
<*> Sound card support --->
<*> Advanced Linux Sound Architecture --->
<*> ALSA for SoC audio support --->
<*> SoC Audio for Texas Instruments chips using eDMA (AM33XX/43XX)
-*- Multichannel Audio Serial Port (McASP) support
<*> SoC Audio for the AM33XX chip based boards
CODEC drivers --->
<*> Wolfson Microelectronics WM8960 CODEC
重新编译内核：
[cpp]
view plain
copy
make ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- -j8
5. 效果
将编译后的内核文件zImage和tq335x.dtb文件拷贝SD卡并启动开发板，按任意键进入uboot命令模式，输入如下指令：
[cpp]
view plain
copy
load mmc 0:1 0x88000000 /boot/tq335x.dtb
load mmc 0:1 0x82000000 /boot/zImage
bootz 0x82000000 - 0x88000000
通过上面的三条指令可以启动内核，完整的Log信息如下：
[cpp]
view plain
copy
Starting kernel ...
[ 0.000000] Booting Linux on physical CPU 0x0
[ 0.000000] Linux version 3.17.2 (lilianrong@smarter) (gcc version 4.7.3 (Ubuntu/Linaro 4.7.3-12ubuntu1) ) #68 SMP Sat Dec 20 00:03:09 CST 2014
[ 0.000000] CPU: ARMv7 Processor [413fc082] revision 2 (ARMv7), cr=10c5387d
[ 0.000000] CPU: PIPT / VIPT nonaliasing data cache, VIPT aliasing instruction cache
[ 0.000000] Machine model: TI AM335x EVM
[ 0.000000] cma: Reserved 16 MiB at 9e800000
[ 0.000000] Memory policy: Data cache writeback
[ 0.000000] HighMem zone: 1048574 pages exceeds freesize 0
[ 0.000000] CPU: All CPU(s) started in SVC mode.
[ 0.000000] AM335X ES2.1 (sgx neon )
[ 0.000000] PERCPU: Embedded 9 pages/cpu @dfa99000 s14336 r8192 d14336 u36864
[ 0.000000] Built 1 zonelists in Zone order, mobility grouping on. Total pages: 129792
[ 0.000000] Kernel command line: console=ttyO0,115200n8 root=/dev/mmcblk0p2 rw rootfstype=ext3 rootwait
[ 0.000000] PID hash table entries: 2048 (order: 1, 8192 bytes)
[ 0.000000] Dentry cache hash table entries: 65536 (order: 6, 262144 bytes)
[ 0.000000] Inode-cache hash table entries: 32768 (order: 5, 131072 bytes)
[ 0.000000] Memory: 484124K/523264K available (6070K kernel code, 666K rwdata, 2444K rodata, 410K init, 8214K bss, 39140K reserved, 0K highmem)
[ 0.000000] Virtual kernel memory layout:
[ 0.000000] vector : 0xffff0000 - 0xffff1000 ( 4 kB)
[ 0.000000] fixmap : 0xffc00000 - 0xffe00000 (2048 kB)
[ 0.000000] vmalloc : 0xe0800000 - 0xff000000 ( 488 MB)
[ 0.000000] lowmem : 0xc0000000 - 0xe0000000 ( 512 MB)
[ 0.000000] pkmap : 0xbfe00000 - 0xc0000000 ( 2 MB)
[ 0.000000] modules : 0xbf000000 - 0xbfe00000 ( 14 MB)
[ 0.000000] .text : 0xc0008000 - 0xc0858bc0 (8515 kB)
[ 0.000000] .init : 0xc0859000 - 0xc08bf800 ( 410 kB)
[ 0.000000] .data : 0xc08c0000 - 0xc0966b50 ( 667 kB)
[ 0.000000] .bss : 0xc0966b50 - 0xc116c6e0 (8215 kB)
[ 0.000000] Hierarchical RCU implementation.
[ 0.000000] RCU restricting CPUs from NR_CPUS=2 to nr_cpu_ids=1.
[ 0.000000] RCU: Adjusting geometry for rcu_fanout_leaf=16, nr_cpu_ids=1
[ 0.000000] NR_IRQS:16 nr_irqs:16 16
[ 0.000000] IRQ: Found an INTC at 0xfa200000 (revision 5.0) with 128 interrupts
[ 0.000000] Total of 128 interrupts on 1 active controller
[ 0.000000] OMAP clockevent source: timer2 at 24000000 Hz
[ 0.000015] sched_clock: 32 bits at 24MHz, resolution 41ns, wraps every 178956969942ns
[ 0.000061] OMAP clocksource: timer1 at 24000000 Hz
[ 0.000798] Console: colour dummy device 80x30
[ 0.000849] Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar
[ 0.000858] ... MAX_LOCKDEP_SUBCLASSES: 8
[ 0.000865] ... MAX_LOCK_DEPTH: 48
[ 0.000873] ... MAX_LOCKDEP_KEYS: 8191
[ 0.000880] ... CLASSHASH_SIZE: 4096
[ 0.000887] ... MAX_LOCKDEP_ENTRIES: 32768
[ 0.000894] ... MAX_LOCKDEP_CHAINS: 65536
[ 0.000901] ... CHAINHASH_SIZE: 32768
[ 0.000909] memory used by lock dependency info: 5167 kB
[ 0.000916] per task-struct memory footprint: 1152 bytes
[ 0.000956] Calibrating delay loop... 996.14 BogoMIPS (lpj=4980736)
[ 0.079039] pid_max: default: 32768 minimum: 301
[ 0.079431] Security Framework initialized
[ 0.079555] Mount-cache hash table entries: 1024 (order: 0, 4096 bytes)
[ 0.079568] Mountpoint-cache hash table entries: 1024 (order: 0, 4096 bytes)
[ 0.081736] CPU: Testing write buffer coherency: ok
[ 0.082916] CPU0: thread -1, cpu 0, socket -1, mpidr 0
[ 0.083033] Setting up static identity map for 0x805bf4f0 - 0x805bf560
[ 0.086259] Brought up 1 CPUs
[ 0.086278] SMP: Total of 1 processors activated.
[ 0.086288] CPU: All CPU(s) started in SVC mode.
[ 0.088875] devtmpfs: initialized
[ 0.097689] VFP support v0.3: implementor 41 architecture 3 part 30 variant c rev 3
[ 0.133508] omap_hwmod: tptc0 using broken dt data from edma
[ 0.133865] omap_hwmod: tptc1 using broken dt data from edma
[ 0.134203] omap_hwmod: tptc2 using broken dt data from edma
[ 0.142102] omap_hwmod: debugss: _wait_target_disable failed
[ 0.200093] pinctrl core: initialized pinctrl subsystem
[ 0.202608] regulator-dummy: no parameters
[ 0.232298] NET: Registered protocol family 16
[ 0.240800] DMA: preallocated 256 KiB pool for atomic coherent allocations
[ 0.243054] cpuidle: using governor ladder
[ 0.243083] cpuidle: using governor menu
[ 0.255025] OMAP GPIO hardware version 0.1
[ 0.270226] omap-gpmc 50000000.gpmc: could not find pctldev for node /pinmux@44e10800/nandflash_pins_s0, deferring probe
[ 0.270268] platform 50000000.gpmc: Driver omap-gpmc requests probe deferral
[ 0.274762] hw-breakpoint: debug architecture 0x4 unsupported.
[ 0.319722] edma-dma-engine edma-dma-engine.0: TI EDMA DMA engine driver
[ 0.321054] vbat: 5000 mV
[ 0.321851] lis3_reg: no parameters
[ 0.325260] SCSI subsystem initialized
[ 0.326060] usbcore: registered new interface driver usbfs
[ 0.326235] usbcore: registered new interface driver hub
[ 0.330180] usbcore: registered new device driver usb
[ 0.331021] omap_i2c 44e0b000.i2c: could not find pctldev for node /pinmux@44e10800/pinmux_i2c0_pins, deferring probe
[ 0.331059] platform 44e0b000.i2c: Driver omap_i2c requests probe deferral
[ 0.331115] omap_i2c 4802a000.i2c: could not find pctldev for node /pinmux@44e10800/pinmux_i2c1_pins, deferring probe
[ 0.331139] platform 4802a000.i2c: Driver omap_i2c requests probe deferral
[ 0.332318] Advanced Linux Sound Architecture Driver Initialized.
[ 0.335684] Switched to clocksource timer1
[ 0.486994] NET: Registered protocol family 2
[ 0.488860] TCP established hash table entries: 4096 (order: 2, 16384 bytes)
[ 0.489040] TCP bind hash table entries: 4096 (order: 5, 147456 bytes)
[ 0.490403] TCP: Hash tables configured (established 4096 bind 4096)
[ 0.490593] TCP: reno registered
[ 0.490617] UDP hash table entries: 256 (order: 2, 20480 bytes)
[ 0.490807] UDP-Lite hash table entries: 256 (order: 2, 20480 bytes)
[ 0.491827] NET: Registered protocol family 1
[ 0.493704] RPC: Registered named UNIX socket transport module.
[ 0.493729] RPC: Registered udp transport module.
[ 0.493738] RPC: Registered tcp transport module.
[ 0.493747] RPC: Registered tcp NFSv4.1 backchannel transport module.
[ 0.495022] hw perfevents: enabled with armv7_cortex_a8 PMU driver, 5 counters available
[ 0.499438] futex hash table entries: 256 (order: 2, 16384 bytes)
[ 0.504727] VFS: Disk quotas dquot_6.5.2
[ 0.504882] Dquot-cache hash table entries: 1024 (order 0, 4096 bytes)
[ 0.507359] NFS: Registering the id_resolver key type
[ 0.507727] Key type id_resolver registered
[ 0.507743] Key type id_legacy registered
[ 0.507886] jffs2: version 2.2. (NAND) (SUMMARY) 漏 2001-2006 Red Hat, Inc.
[ 0.508320] msgmni has been set to 977
[ 0.513238] io scheduler noop registered
[ 0.513269] io scheduler deadline registered
[ 0.513341] io scheduler cfq registered (default)
[ 0.515815] pinctrl-single 44e10800.pinmux: 142 pins at pa f9e10800 size 568
[ 0.520975] backlight supply power not found, using dummy regulator
[ 0.524309] Serial: 8250/16550 driver, 4 ports, IRQ sharing enabled
[ 0.530939] omap_uart 44e09000.serial: no wakeirq for uart0
[ 0.531575] 44e09000.serial: ttyO0 at MMIO 0x44e09000 (irq = 88, base_baud = 3000000) is a OMAP UART0
[ 1.231857] console [ttyO0] enabled
[ 1.241315] omap_rng 48310000.rng: OMAP Random Number Generator ver. 20
[ 1.248987] [drm] Initialized drm 1.1.0 20060810
[ 1.261218] [drm] Supports vblank timestamp caching Rev 2 (21.10.2013).
[ 1.268316] [drm] No driver support for vblank timestamp query.
[ 1.320991] Console: switching to colour frame buffer device 100x30
[ 1.332042] tilcdc 4830e000.lcdc: fb0: frame buffer device
[ 1.337919] tilcdc 4830e000.lcdc: registered panic notifier
[ 1.343814] [drm] Initialized tilcdc 1.0.0 20121205 on minor 0
[ 1.380804] brd: module loaded
[ 1.398539] loop: module loaded
[ 1.404724] mtdoops: mtd device (mtddev=name/number) must be supplied
[ 1.414737] usbcore: registered new interface driver asix
[ 1.420619] usbcore: registered new interface driver ax88179_178a
[ 1.427154] usbcore: registered new interface driver cdc_ether
[ 1.433416] usbcore: registered new interface driver smsc95xx
[ 1.439572] usbcore: registered new interface driver net1080
[ 1.445625] usbcore: registered new interface driver cdc_subset
[ 1.451932] usbcore: registered new interface driver zaurus
[ 1.457997] usbcore: registered new interface driver cdc_ncm
[ 1.465136] usbcore: registered new interface driver cdc_wdm
[ 1.471412] usbcore: registered new interface driver usb-storage
[ 1.477942] usbcore: registered new interface driver usbtest
[ 1.486105] mousedev: PS/2 mouse device common for all mice
[ 1.496690] omap_rtc 44e3e000.rtc: rtc core: registered 44e3e000.rtc as rtc0
[ 1.504827] i2c /dev entries driver
[ 1.508655] Driver for 1-wire Dallas network protocol.
[ 1.517293] omap_wdt: OMAP Watchdog Timer Rev 0x01: initial timeout 60 sec
[ 1.527282] omap_hsmmc 48060000.mmc: unable to get vmmc regulator -517
[ 1.534612] platform 48060000.mmc: Driver omap_hsmmc requests probe deferral
[ 1.544215] ledtrig-cpu: registered to indicate activity on CPUs
[ 1.551195] usbcore: registered new interface driver usbhid
[ 1.557065] usbhid: USB HID core driver
[ 1.575960] davinci_evm sound: ASoC: CODEC (null) not registered
[ 1.582524] davinci_evm sound: snd_soc_register_card failed (-517)
[ 1.589121] platform sound: Driver davinci_evm requests probe deferral
[ 1.596830] oprofile: using arm/armv7
[ 1.601311] TCP: cubic registered
[ 1.604789] Initializing XFRM netlink socket
[ 1.609445] NET: Registered protocol family 17
[ 1.614179] NET: Registered protocol family 15
[ 1.619196] Key type dns_resolver registered
[ 1.623867] omap_voltage_late_init: Voltage driver support not added
[ 1.630565] sr_dev_init: No voltage domain specified for smartreflex0. Cannot initialize
[ 1.639038] sr_dev_init: No voltage domain specified for smartreflex1. Cannot initialize
[ 1.648614] ThumbEE CPU extension supported.
[ 1.653130] Registering SWP/SWPB emulation handler
[ 1.658211] SmartReflex Class3 initialized
[ 1.667886] omap-gpmc 50000000.gpmc: GPMC revision 6.0
[ 1.674877] nand: device found, Manufacturer ID: 0xec, Chip ID: 0xd3
[ 1.681647] nand: Samsung NAND 1GiB 3,3V 8-bit
[ 1.686312] nand: 1024MiB, SLC, page size: 2048, OOB size: 64
[ 1.692312] nand: error: CONFIG_MTD_NAND_OMAP_BCH not enabled
[ 1.698428] omap2-nand: probe of omap2-nand.0 failed with error -22
[ 1.790962] tps65910 0-002d: No interrupt support, no core IRQ
[ 1.807488] vrtc: 1800 mV
[ 1.810865] vrtc: supplied by vbat
[ 1.818190] vio: at 1500 mV
[ 1.821460] vio: supplied by vbat
[ 1.828397] vdd_mpu: 912 <--> 1312 mV at 1325 mV
[ 1.833532] vdd_mpu: supplied by vbat
[ 1.840598] vdd_core: 912 <--> 1150 mV at 1137 mV
[ 1.845924] vdd_core: supplied by vbat
[ 1.852537] vdd3: 5000 mV
[ 1.858001] vdig1: at 1800 mV
[ 1.861420] vdig1: supplied by vbat
[ 1.867904] vdig2: at 1800 mV
[ 1.871302] vdig2: supplied by vbat
[ 1.878529] vpll: at 1800 mV
[ 1.881866] vpll: supplied by vbat
[ 1.888426] vdac: at 1800 mV
[ 1.891747] vdac: supplied by vbat
[ 1.898169] vaux1: at 1800 mV
[ 1.901568] vaux1: supplied by vbat
[ 1.908027] vaux2: at 3300 mV
[ 1.911421] vaux2: supplied by vbat
[ 1.917833] vaux33: at 3300 mV
[ 1.921323] vaux33: supplied by vbat
[ 1.927806] vmmc: 1800 <--> 3300 mV at 3300 mV
[ 1.932761] vmmc: supplied by vbat
[ 1.938842] vbb: at 3000 mV
[ 1.942302] vbb: supplied by vbat
[ 1.949841] omap_i2c 44e0b000.i2c: bus 0 rev0.11 at 400 kHz
[ 1.963667] omap_i2c 4802a000.i2c: bus 1 rev0.11 at 100 kHz
[ 2.007363] wm8960 0-001a: No platform data supplied
[ 2.084399] mmc0: host does not support reading read-only switch. assuming write-enable.
[ 2.095817] mmc0: new high speed SDHC card at address aaaa
[ 2.104312] mmcblk0: mmc0:aaaa SL16G 14.8 GiB
[ 2.116665] mmcblk0: p1 p2
[ 2.131506] davinci_evm sound: wm8960-hifi <-> 4803c000.mcasp mapping ok
[ 2.215823] davinci_mdio 4a101000.mdio: davinci mdio revision 1.6
[ 2.222212] davinci_mdio 4a101000.mdio: detected phy mask ffffffde
[ 2.232273] libphy: 4a101000.mdio: probed
[ 2.236597] davinci_mdio 4a101000.mdio: phy[0]: device 4a101000.mdio:00, driver unknown
[ 2.244957] davinci_mdio 4a101000.mdio: phy[5]: device 4a101000.mdio:05, driver unknown
[ 2.254567] cpsw 4a100000.ethernet: Detected MACID = c4:ed:ba:88:b5:e4
[ 2.266507] input: gpio_keyad@0 as /devices/gpio_keyad@0/input/input0
[ 2.276227] omap_rtc 44e3e000.rtc: setting system clock to 2000-01-01 00:00:00 UTC (946684800)
[ 2.285247] sr_init: No PMIC hook to init smartreflex
[ 2.290884] sr_init: platform driver register failed for SR
[ 2.313832] lis3_reg: disabling
[ 2.317496] ALSA device list:
[ 2.320598] #0: AM335x-EVM
[ 2.434398] kjournald starting. Commit interval 5 seconds
[ 2.444085] EXT3-fs (mmcblk0p2): using internal journal
[ 2.452049] EXT3-fs (mmcblk0p2): recovery complete
[ 2.457123] EXT3-fs (mmcblk0p2): mounted filesystem with ordered data mode
[ 2.464445] VFS: Mounted root (ext3 filesystem) on device 179:2.
[ 2.474111] devtmpfs: mounted
[ 2.478057] Freeing unused kernel memory: 408K (c0859000 - c08bf000)
----------mount all..........
----------Starting mdev......
Please press Enter to activate this console.
@tq335x #
从Log信息中很容易看到ALSA device list已经出现了AM335x-EVM项。到这里TQ335x已经能够识别到声卡了。
6. 测试
测试ALSA声卡驱动的常用方法是移植alsa-lib和alsa-utils，使用alsa-utils提供的arecord来测试声卡的录音，aplay来测试播放。alsa-lib和alsa-utils的移植教程有很多，这里我就不多讲了（如果有不明白这块的可以留言）。
录音测试：
[cpp]
view plain
copy
arecord -f cd test.wav
播放测试：
[cpp]
view plain
copy
aplay test.wav
播放时就可以听到之前录制的声音的。
7. 总结
调试声卡驱动大约进行了三周，也算是略有心得。
(1) 必要的工具：我调试的时候手头上工具不够齐全。我是在家里调试的，没有示波器，也就无法测量BCLK和LRCLK时钟，调试了很久都不知道WM8960到底有没有工作，因此，必要的工具可以有效的提高调试效率。
(2) 先调试放音，wm8960放音再调试录音。放音可以很容易检测效果，录音则没有方便的检测手段。同时，放音的配置比录音要简单些，可以有效检测驱动部分是否存在问题。
以上是完整的WM8960驱动移植过程，如果疑问欢迎留言讨论。
本文作者：girlkoo
本文连接：/article/1329492.html
内容来自用户分享和网络整理，不保证内容的准确性，如有侵权内容，可联系管理员处理 
相关文章推荐
- javaweb中HTTP协议
- android学习 一
- ARM六种寻址方式的汇编实现
- Linux 中断底半部机制
- Android的menu(菜单)按钮的使用（by 星空武哥）
- Linux下编写运行访问MYSQL的程序以及MYSQL在linux下的下载安装
- 20150116--Cookie+Session-02
- 机器人网站查询
- WEB服务器6--IIS架构补充篇
- 第八周——第九周学习总结
- Linux系统 工作笔记
- MySQL_Php.php
- codec-wm8960分析
- 有效回文串
- 杭州--4.21
- 数据挖掘导论--数据
- 我和我的同伴是如何用具体的代码例子，说明源代码管理的基本操作
- QLabel显示边框
- 机器人的雅克比矩阵
- Flink如何应对背压问题