經過一段時間的調試，終于調好了tq335x的聲霸卡驅動。tq335x采用的codec是wm8960，本文來總結下wm8960驅動在am335x平台上的移植方法。linux聲霸卡驅動架構有oss和alsa兩種架構，目前最常用的架構是alsa，本文也使用alsa架構對wm8960驅動進行移植。
asoc是對alsa驅動架構的進一步封裝。asoc将alsa驅動中的各子產品抽象為三部分：platform、codec和machine。platform主要是平台硬體驅動，包括soc的iis子產品、dma等，在本文中就是指am335x的mcasp子產品及am335x用于音頻讀寫操作的edma。codec是編解碼晶片驅動，在本文中就是wm8960。machine是用來描述單闆音頻系統連接配接關系的驅動，在本文中其作用是将wm8960與mcasp綁定起來，注冊聲霸卡裝置節點。由于3.17版本的核心已經帶有ti維護的mcasp驅動和wolf公司維護的wm8960驅動，是以，原理上講，我們隻需要編寫machine部分，建立wm8960與mcasp的連接配接關系即可。不幸的是wolf對wm8960的維護不是太完善，還需要我們進一步修改。下面我們來看下wm8960在tq335x上的移植方法。
1. 在dts中添加聲霸卡資訊
step1. 完善sound資訊
在dts有一個節點名為sound，該節點用來描述單闆上聲霸卡裝置資訊，修改後的内容如下：
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";
};
含義解釋：
(1) compatible = "ti,tq-evm-audio" --> 指定聲霸卡相容的裝置，與machine驅動中的compatible比對。
(2) ti,model = "am335x-evm" --> 聲霸卡的名稱，原則上講可以随意指定，但最好具有一定的可讀性，這裡沒有修改。
(3) ti,audio-codec = <&wm8960> --> 指定單闆使用的codec，具體的codec資訊由其指向的節點wm8960描述。
(4) ti,mcasp-controller = <&mcasp1> --> 指定單闆使用的codec連接配接到am335x的mcasp1上，mcasp1的具體資訊由其指向的節點mcasp1描述。
(5) ti,codec-clock-rate = <24576000> --> 指定codec的mclk時鐘頻率，機關是hz。tq335x的codec使用24.576mhz的有源晶振提供mclk，故設定為24576000。
(6) ti,audio-routing --> dapm資訊描述，用來指定codec與mcasp的連接配接關系。此處若不設定，則需要在machine驅動中進行設定。本文在這裡做了修改。
step2. 完善codec資訊
通過閱讀tq335x的原理圖可知，wm8960的控制端口連接配接到了am335x的i2c0端口上，是以，可以i2c0節點内添加如下資訊（類似上篇文章中觸摸裝置驅動節點）：
wm8960: wm8960@1a {
compatible = "wlf,wm8960";
reg = <0x1a>;
(1) compatible = "wlf,wm8960" --> 指定codec相容裝置，與codec驅動中的compatible比對。
(2) reg = <0x1a> --> wm8960的i2c位址是1a，故設定為0x1a。
step3. 完善platform資訊
am335x的platform資訊主要指mcasp和emda設定資訊。由于預設的dts已經配置好了mcasp及edma的大部分資訊，需要我們配置的是mcasp的pinmux和i2s資訊。
(1) 修改pinmux資訊需要具體參考tq335x的原理圖，下面是根據原理圖中的引腳連接配接方式修改的pinmux資訊，如果有啥不懂的可以留言讨論：
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的配置資訊需要在mcasp1節點中修改，具體的修改如下：
&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>;
含義：
(1) pinctrl-0 = <&am335x_evm_audio_pins> --> 指定mcasp1的pinmux資訊。
(2) op-mode = <0> --> 指定mcasp為i2s工作模式。
(3) tdm-slots = <2> --> 指定通道數。am335x的手冊以更廣泛意義的單詞slot命名，具體到i2s接口，其含義就是channel。
(4) serial-dir --> 指定serializer的方向。am335x的手冊中提到每個mcasp有16個serializer，但am335x這款晶片的mcaps隻有4個serializer，分别用于axr0、axr1、axr2和arx3。由于tq335x中将axr0作為發送（輸出）、arx1作為接收（輸入）且沒有arx2和arx3，故設定4個serial-dir為1、2、0、0（0表示沒有使用，1表示發送，2表示接收）。
(5) tx-num-evt = <1> --> 指定發送fifo大小，本文設定為1。
(6) rx-num-evt = <1> --> 指定接收fifo大小，本文設定為1。
至此，就完成了dts的全部配置，後面我會将完整的dts檔案上傳到我的資源。
2. codec驅動完善
step1. 修改codec驅動，使其支援dts
由于我們在dts中指定了codec的compatible為"wlf,wm8960"，而linux核心自帶的wm8960驅動并沒有支援新式的dts模式關聯。修改方法很簡單，添加i2c_driver的.driver中指定of_match_table即可，修改後的代碼片段如下：
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的初始化資訊
預設的wm8960驅動初始化資訊不夠完整，還需要對wm8960進行額外的初始化，修改後的代碼片段如下：
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;
}
具體的含義可以參考wm8960的晶片手冊，這裡我就不一一介紹了。
step3. 調整wm8960驅動結構
核心中自帶的wm8960驅動結構很舊，編寫machine是需要過多的了解codec晶片内部細節，本文對wm8960的驅動結構進行了調整，可以使machine忽略codec的内部細節。
修改的大體内容如下：
(1) 添加set_sysclk函數，接收machine設定的sysclk時鐘頻率。具體本文就是dts中設定的24576000。
(2) 在hw_params中添加bclk、dacclk、adcclk的配置操作。hw_params可以根據參數和sysclk對以上參數進行設定，放在這裡很合适。
(3) 去除函數wm8960_set_dai_clkdiv，并将wm8960_set_dai_pll設定為驅動内部函數，不作為set_pll接口提供給核心驅動（實際上核心驅動也不調用這個函數）。
step4. 修改wm8960的route資訊
根據tq335x的原理圖可知，使用wm8960進行錄音或放音時使用的lrclk是同一個，都是dacclk，故在snd_soc_dapm_route添加如下兩行資訊：
{ "left dac", null, "left input mixer" },
{ "right dac", null, "right input mixer" },
這樣在錄音時也會使能dac産生lrclk。
由于調試時間比較長，可能有些修改我沒有描述到，完整的wm8960.c檔案我會一并上傳到我的資源，可以下載下傳參考。
3. 編寫machine驅動
核心代碼有個很好的例子就是davinci-evm.c，這是am335x-evm評估闆的machine驅動，該評估采用的codec并不是wm8960，是以，我們在該檔案中添加wm8960資訊即可。具體的修改如下：
step1. 添加compatible資訊。修改後的内容如下：
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. 實作em_dai_wm8960。需要添加如下代碼：
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,
(1) codec_dai_name = "wm8960-hifi" --> 指定codec裝置名稱，與wm8960.c中指定的相同即可。
(2) ops --> 指定wm8960的各種操作函數，本文僅實作了hw_params函數。
(3) init --> 指定wm8960的初始化函數，主要是完成dapm相關的初始化。
(4) dai_fmt --> 指定音頻的接口方式、主從關系和時鐘翻轉資訊。snd_soc_daifmt_i2s表示音頻接口采用i2s協定；snd_soc_daifmt_cbm_cfm表示codec的bclk為master，lrclk為master，即wm8960為主，am335x為從；snd_soc_daifmt_nb_nf表示bclk和lrclk都不需要翻轉。
step3.實作evm_wm8960_init
這一部分主要是dapm相關的設定，本人了解也不是非常深刻，直接貼上代碼，具體如下：
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 );
step4. 實作evm_wm8960_ops及相關函數，需要添加如下代碼：
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)
/* set the cpu system clock */
ret = snd_soc_dai_set_sysclk(cpu_dai, 0, sysclk, snd_soc_clock_in);
static struct snd_soc_ops evm_wm8960_ops = {
.startup = evm_startup,
.shutdown = evm_shutdown,
.hw_params = evm_wm8960_hw_params,
至此，就完成了代碼移植的全部工作，修改涉及到的三個檔案是：tq335x.dts、davinci-evm.c和wm8960.c，修改後的這三個檔案我會上傳到我的資源，如有需要，請去我的資源中下載下傳。
4. 配置核心
完成了代碼的移植工作之後還需要對核心進一步配置。預設的核心将alsa作為module加載，本文将編譯進核心。具體步驟如下：
step1. 修改sound/soc/codecs/kconfig，添加wm8960編譯選項，修改後的内容如下：
config snd_soc_wm8960
tristate "wolfson microelectronics wm8960 codec"
depends on i2c && input
step2. 通過menuconfig配置核心
執行指令：
make arch=arm cross_compile=arm-linux-gnueabi- menuconfig
進行如下修改：
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
重新編譯核心：
make arch=arm cross_compile=arm-linux-gnueabi- -j8
5. 效果
将編譯後的核心檔案zimage和tq335x.dtb檔案拷貝sd卡并啟動開發闆，按任意鍵進入uboot指令模式，輸入如下指令：
load mmc 0:1 0x88000000 /boot/tq335x.dtb
load mmc 0:1 0x82000000 /boot/zimage
bootz 0x82000000 - 0x88000000
通過上面的三條指令可以啟動核心，完整的log資訊如下：
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 #
從log資訊中很容易看到alsa device list已經出現了am335x-evm項。到這裡tq335x已經能夠識别到聲霸卡了。
6. 測試
測試alsa聲霸卡驅動的常用方法是移植alsa-lib和alsa-utils，使用alsa-utils提供的arecord來測試聲霸卡的錄音，aplay來測試播放。alsa-lib和alsa-utils的移植教程有很多，這裡我就不多講了（如果有不明白這塊的可以留言）。
錄音測試：
arecord -f cd test.wav
播放測試：
aplay test.wav
播放時就可以聽到之前錄制的聲音的。
7. 總結
調試聲霸卡驅動大約進行了三周，也算是略有心得。
(1) 必要的工具：我調試的時候手頭上工具不夠齊全。我是在家裡調試的，沒有示波器，也就無法測量bclk和lrclk時鐘，調試了很久都不知道wm8960到底有沒有工作，是以，必要的工具可以有效的提高調試效率。
(2) 先調試放音，wm8960放音再調試錄音。放音可以很容易檢測效果，錄音則沒有友善的檢測手段。同時，放音的配置比錄音要簡單些，可以有效檢測驅動部分是否存在問題。
以上是完整的wm8960驅動移植過程，如果疑問歡迎留言讨論。