WM8960驱动的移植记录

sparkle-cliz

一，前言：WM8960是一个音频CODEC，与CPU通过I2S进行数据传输，CPU通过I2C对WM8960进行控制。
Kernel:linux- 2.6.28.10 +TCC8900平台
二，实现I2C控制接口，在drivers/i2c/chips下加一个i2c驱动。Tcc_wm8960.c
#include
#include
#include
#include 2c.h>

#define WM8960_SLAVE_ADDR  0x1a
static unsigned short probe_i2c[] = {0, WM8960_SLAVE_ADDR, I2C_CLIENT_END}; /* { i2c_num, i2c_addr } */
static unsigned short dummy[] = {I2C_CLIENT_END};

static struct i2c_client_address_data addr_data = {
       .normal_i2c = dummy,
       .probe = probe_i2c,
       .ignore = dummy,
};

static struct i2c_driver wm8960_i2c_driver;
struct i2c_client *wm8960_i2c_client;
EXPORT_SYMBOL(wm8960_i2c_client);

static int wm8960_i2c_probe(struct i2c_adapter *adap, int addr, int kind)
{
       struct i2c_client *i2c;

       i2c = kzalloc(sizeof(*i2c), GFP_KERNEL);
       if (!i2c)
              return -ENOMEM;

       strcpy(i2c->name, "WM8960");
       i2c->flags = 0;
       i2c->addr = addr;
       i2c->adapter = adap;
       i2c->driver = &wm8960_i2c_driver;

       wm8960_i2c_client = i2c;

       return i2c_attach_client(i2c);
}

static int wm8960_i2c_detach(struct i2c_client *client)
{
       i2c_detach_client(client);
       kfree(wm8960_i2c_client);
       return 0;
}

static int wm8960_i2c_attach(struct i2c_adapter *adap)
{
       return i2c_probe(adap, &addr_data, wm8960_i2c_probe);
}

static struct i2c_driver wm8960_i2c_driver = {
       .driver = {
              .name = "WM8960",
              .owner = THIS_MODULE,
       },
       .id = -1,
       .attach_adapter = wm8960_i2c_attach,
       .detach_client = wm8960_i2c_detach,
};

static int __init wm8960_i2c_init(void)
{
       return i2c_add_driver(&wm8960_i2c_driver);
}

static void __exit wm8960_i2c_exit(void)
{
       i2c_del_driver(&wm8960_i2c_driver);
}

module_init(wm8960_i2c_init);
module_exit(wm8960_i2c_exit);

MODULE_AUTHOR("Telechips Inc. SYS4-3 linux@telechips.com");
MODULE_DESCRIPTION("WM8960 I2C driver");
MODULE_LICENSE("GPL");

这个i2c驱动写得很简单，最重要的是导出了wm8960_i2c_client这样一个i2c_client，写wm8960寄存器就是通过这个i2c_client完成的。
三，参照sound/soc/codecs目录下的wm8731.c写出一个wm8960.c。
四，修改一下sound/soc/tcc/tcc_board.c，主要是与wm8960有联系的地方改一下。关于声卡驱动的架构以后有空再写一篇分析出来。
五，修改一下相应目录下的Kconfig和Makefile。
六，测试结果如下：
/nand2/mplayer # ./mplayer-y justonelastdance.mp3
MPlayer SVN-r4-4.3.2 (C) 2000-2009 MPlayer Team

Playing justonelastdance.mp3.
Audio only file format detected.
Clip info:
Title: Just One Last Dance
Artist: Sarah Connor
Album: Key To My Soul
Year: 2003
Comment: http://www.joyui.com        
Track: 3
Genre: Pop
==========================================================================
Opening audio decoder: [mp3lib] MPEG layer-2, layer-3
AUDIO: 44100 Hz, 2 ch, s16le, 192.0 kbit/13.61% (ratio: 24000->176400)
Selected audio codec: [mp3] afm: mp3lib (mp3lib MPEG layer-2, layer-3)
==========================================================================
[AO OSS] audio_setup: Can't open audio device /dev/dsp: No such device or address
alsa-init: requested format: 44100 Hz, 2 channels, 9
alsa-init: using ALSA 1.0.15
soc_pcm_open
[AO] device [default], mode [0], return [0]
== alsa-debug ==
totsize=0x10000 period=0x4000  period num=4
== alsa-debug == set_dma_outbuffer, addr[0x41040000], len[65536], period[16384]
== alsa-debug == [set_dma_outbuffer] HwTxDaParam [0xFFF00004]
== alsa-debug == [set_dma_outbuffer] HwTxDaTCnt [1023]
======================================
    set [2] channels
======================================
AO: [alsa] 44100Hz 2ch s16le (2 bytes per sample)
Video: no video
Starting playback...
A:   8.3 (08.2) of 268.0 (04:28.0) 10.4%                                       

MPlayer interrupted by signal 2 in module: play_audio
A:   8.4 (08.4) of 268.0 (04:28.0) 10.4%

动人的声音就出来了。

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