s3c2440 uda1341声卡驱动分析（oos）-阿里云开发者社区

1，驱动架构：
驱动分两个层次，上层是平台设备驱动，底层是audio驱动与mixer驱动。

（1）标准的平台设备驱动结构，probe与remove两个函数。
probe：
获得平台资源->申请内存区域-io内存重映射->获得并使能时钟->设置gpio口->初始化iis总线-> 初始化uda1341->audio dma初始化->注册dsp和mixer->释放内存区域。
代码及注释：

static int s3c2410iis_probe(struct platform_device *pdev) {

struct resource *res;
unsigned long flags;
int ret;

DPRINTK("s3c2410iis_probe\n");

//获得平台设备资源

res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (res == NULL) {
printk(KERN_INFO PFX "failed to get memory region resouce\n");
return -ENOENT;
}

//申请可用内存

res = request_mem_region(res->start, RESSIZE(res), pdev->name);
if(res == 0){
printk(KERN_INFO PFX "failed to request io memory region.\n");
return -ENOENT;
}

//io内存重映射

iis_base = ioremap(res->start, RESSIZE(res));
if(iis_base == 0){
printk(KERN_INFO PFX "failed to ioremap() io memory region.\n"); ret = -EINVAL;
goto free_mem_region;
}

//获得时钟资源

iis_clock = clk_get(&pdev->dev, "iis");
if (iis_clock == NULL) {
printk(KERN_INFO PFX "failed to find clock source\n");
return -ENOENT;
}
/**************************modify by lfc*****************************/
clk_enable(iis_clock);//使能时钟

/*****************************end add********************************/
//禁用本地中断，gpio口设置，恢复中断

local_irq_save(flags);

/* GPB 4: L3CLOCK, OUTPUT */
s3c2410_gpio_cfgpin(S3C2410_GPB4, S3C2410_GPB4_OUTP);
s3c2410_gpio_pullup(S3C2410_GPB4,1);
/* GPB 3: L3DATA, OUTPUT */
s3c2410_gpio_cfgpin(S3C2410_GPB3,S3C2410_GPB3_OUTP);
/* GPB 2: L3MODE, OUTPUT */
s3c2410_gpio_cfgpin(S3C2410_GPB2,S3C2410_GPB2_OUTP);
s3c2410_gpio_pullup(S3C2410_GPB2,1);
/* GPE 3: I2SSDI */
s3c2410_gpio_cfgpin(S3C2410_GPE3,S3C2410_GPE3_I2SSDI);
s3c2410_gpio_pullup(S3C2410_GPE3,1);
/* GPE 0: I2SLRCK */
s3c2410_gpio_cfgpin(S3C2410_GPE0,S3C2410_GPE0_I2SLRCK);
s3c2410_gpio_pullup(S3C2410_GPE0,1);
/* GPE 1: I2SSCLK */
s3c2410_gpio_cfgpin(S3C2410_GPE1,S3C2410_GPE1_I2SSCLK);
s3c2410_gpio_pullup(S3C2410_GPE1,1);
/* GPE 2: CDCLK */
s3c2410_gpio_cfgpin(S3C2410_GPE2,S3C2410_GPE2_CDCLK);
s3c2410_gpio_pullup(S3C2410_GPE2,1);
/* GPE 4: I2SSDO */
s3c2410_gpio_cfgpin(S3C2410_GPE4,S3C2410_GPE4_I2SSDO);
s3c2410_gpio_pullup(S3C2410_GPE4,1);

local_irq_restore(flags);

init_s3c2410_iis_bus();//初始化iis

init_uda1341();//初始化uda1341

//初始化dma ch1 ch2

output_stream.dma_ch = DMA_CH2;

if (!audio_init_dma(&output_stream, "UDA1341 out") & DMACH_LOW_LEVEL) {
audio_clear_dma(&output_stream,&s3c2410iis_dma_out);
printk( KERN_WARNING AUDIO_NAME_VERBOSE
": unable to get DMA channels\n" );
return -EBUSY;
}

input_stream.dma_ch = DMA_CH1;

if (!audio_init_dma(&input_stream, "UDA1341 in") & DMACH_LOW_LEVEL) {
audio_clear_dma(&input_stream,&s3c2410iis_dma_in);
printk( KERN_WARNING AUDIO_NAME_VERBOSE
": unable to get DMA channels\n" );
return -EBUSY;
}

//注册dsp及mixer

audio_dev_dsp = register_sound_dsp(&smdk2410_audio_fops, -1);
audio_dev_mixer = register_sound_mixer(&smdk2410_mixer_fops, -1);

printk(AUDIO_NAME_VERBOSE " initialized\n");

//释放内存区域

free_mem_region:
release_mem_region(res->start, RESSIZE(res));

return 0;
}

remove:
禁用时钟->取消dsp mixer注册->清除dma

static int s3c2410iis_remove(struct platform_device *dev) {
DPRINTK("s3c2410iis_remove\n");

if (iis_clock != NULL){
clk_disable(iis_clock);
clk_put(iis_clock);
iis_clock = NULL;
}

unregister_sound_dsp(audio_dev_dsp);
unregister_sound_mixer(audio_dev_mixer);
audio_clear_dma(&output_stream,&s3c2410iis_dma_out);
audio_clear_dma(&input_stream,&s3c2410iis_dma_in); /* input */
printk(AUDIO_NAME_VERBOSE " unloaded\n");

return 0;
}

uda1341的初始化：
设置gpio口->uda1341复位->uda1341设置

static void init_uda1341(void)
{

/* GPB 4: L3CLOCK */
/* GPB 3: L3DATA */
/* GPB 2: L3MODE */

unsigned long flags;

DPRINTK("init_uda1341\n");

uda1341_volume = 62 - ((DEF_VOLUME * 61) / 100);
uda1341_boost = 0;
// uda_sampling = DATA2_DEEMP_NONE;

// uda_sampling &= ~(DATA2_MUTE);

local_irq_save(flags);

s3c2410_gpio_setpin(S3C2410_GPB2,1);//L3MODE=1

s3c2410_gpio_setpin(S3C2410_GPB4,1);//L3CLOCK=1

local_irq_restore(flags);

uda1341_l3_address(UDA1341_REG_STATUS);
uda1341_l3_data(0x40 | STAT0_SC_384FS | STAT0_IF_MSB|STAT0_DC_FILTER); // reset uda1341

uda1341_l3_data(STAT1 | STAT1_ADC_ON | STAT1_DAC_ON);

uda1341_l3_address(UDA1341_REG_DATA0);
// uda1341_l3_data(DATA0 |DATA0_VOLUME(0x0)); // maximum volume

uda1341_l3_data(DATA0 | DATA0_VOLUME(uda1341_volume));//lfc

uda1341_l3_data(DATA1 |DATA1_BASS(uda1341_boost)| DATA1_TREBLE(0));
uda1341_l3_data((DATA2 |DATA2_DEEMP_NONE) &~(DATA2_MUTE));
uda1341_l3_data(EXTADDR(EXT2));
uda1341_l3_data(EXTDATA(EXT2_MIC_GAIN(0x6)) | EXT2_MIXMODE_CH1);//input channel 1 select(input channel 2 off)

}

（2）底层的audio和mixer其实就是字符设备，完成file_operations结构体后在上面说的probe函数中注册
audio驱动：

fops结构体

static struct file_operations smdk2410_audio_fops = {
llseek: smdk2410_audio_llseek,
write: smdk2410_audio_write,
read: smdk2410_audio_read,
poll: smdk2410_audio_poll,
ioctl: smdk2410_audio_ioctl,
open: smdk2410_audio_open,
release: smdk2410_audio_release
};

write：
判断打开标志是否可写->判断BUFFER内存空间是否可用->判断阻塞方式还是非阻塞方式->循环写入内存块，并将写好的内存块加入dma队列->返回传输字节数

static ssize_t smdk2410_audio_write(struct file *file, const char *buffer,
size_t count, loff_t * ppos)
{
const char *buffer0 = buffer;
audio_stream_t *s = &output_stream;
int chunksize, ret = 0;

DPRINTK("audio_write : start count=%d\n", count);

switch (file->f_flags & O_ACCMODE) {
case O_WRONLY:
case O_RDWR:
break;
default:
DPRINTK("EPERM\n");
return -EPERM;
}

if (!s->buffers && audio_setup_buf(s)){
DPRINTK("ENOMEM\n");
return -ENOMEM;
}

count &= ~0x03;

while (count > 0) {
audio_buf_t *b = s->buf;

if (file->f_flags & O_NONBLOCK) {
ret = -EAGAIN;
if (down_trylock(&b->sem)){
DPRINTK("down_trylock error\n");
break;
}
} else {
ret = -ERESTARTSYS;
if (down_interruptible(&b->sem)){
DPRINTK("down_interruptible error\n");
break;
}
}

if (audio_channels == 2) {//使用双频道

chunksize = s->fragsize - b->size;//当前内存块可供使用空间

if (chunksize > count)
chunksize = count;
DPRINTK("write %d to %d\n", chunksize, s->buf_idx);
if (copy_from_user(b->start + b->size, buffer, chunksize)) {
DPRINTK("copy_from_user error\n");
up(&b->sem);
return -EFAULT;
}
b->size += chunksize;//更新当前内存块的使用情况

} else {//单频道

chunksize = (s->fragsize - b->size) >> 1;

if (chunksize > count)
chunksize = count;
DPRINTK("write %d to %d\n", chunksize*2, s->buf_idx);
if (copy_from_user_mono_stereo(b->start + b->size, buffer, chunksize)) {
DPRINTK("copy_from_user_mono_stereo error\n");
up(&b->sem);
return -EFAULT;
}
b->size += chunksize*2;
}

buffer += chunksize;
count -= chunksize;
if (b->size s->fragsize) {
up(&b->sem);
break;
}
/* 填满一块内存就交给dma去处理 */
if((ret = s3c2410_dma_enqueue(s->dma_ch, (void *) b, b->dma_addr, b->size))) {
printk("dma enqueue failed.\n");
return ret;
}
/* 把内存块加入dma队列后继续填写下一内存块 */
b->size = 0;
NEXT_BUF(s, buf);
}

if ((buffer - buffer0))
ret = buffer - buffer0;//返回已传输的字节数

DPRINTK("audio_write : end count=%d\n\n", ret);

return ret;
}

read:
判断buffer内存空间是否为空，若未空则设置buffer空间，并将buffer内存块放入dma队列->循环将内存块数据读入用户空间->返回读出字节数

static ssize_t smdk2410_audio_read(struct file *file, char *buffer,
size_t count, loff_t * ppos)
{
const char *buffer0 = buffer;
audio_stream_t *s = &input_stream;
int chunksize, ret = 0;

DPRINTK("audio_read: count=%d\n", count);
/*
if (ppos != &file->f_pos)
return -ESPIPE;
*/
if (!s->buffers) {
int i;

if (audio_setup_buf(s))
return -ENOMEM;

for (i = 0; i s->nbfrags; i++) {
audio_buf_t *b = s->buf;
down(&b->sem);
s3c2410_dma_enqueue(s->dma_ch, (void *) b, b->dma_addr, s->fragsize);
NEXT_BUF(s, buf);
}
}

while (count > 0) {
audio_buf_t *b = s->buf;

/* Wait for a buffer to become full */
if (file->f_flags & O_NONBLOCK) {
ret = -EAGAIN;
if (down_trylock(&b->sem))
break;
} else {
ret = -ERESTARTSYS;
if (down_interruptible(&b->sem))
break;
}

chunksize = b->size;
if (chunksize > count)
chunksize = count;
DPRINTK("read %d from %d\n", chunksize, s->buf_idx);
if (copy_to_user(buffer, b->start + s->fragsize - b->size,
chunksize)) {
up(&b->sem);
return -EFAULT;
}

b->size -= chunksize;

buffer += chunksize;
count -= chunksize;
if (b->size > 0) {
up(&b->sem);
break;
}

/* Make current buffer available for DMA again */
s3c2410_dma_enqueue(s->dma_ch, (void *) b, b->dma_addr, s->fragsize);

NEXT_BUF(s, buf);
}

if ((buffer - buffer0))
ret = buffer - buffer0;

// DPRINTK("audio_read: return=%d\n", ret);

return ret;
}

poll:
可读可写两部分判断是否可以无阻塞地读写（buffer信号量为大于0则可以）

static unsigned int smdk2410_audio_poll(struct file *file,struct poll_table_struct *wait)
{
unsigned int mask = 0;
int i;
DPRINTK("audio_poll(): mode=%s\n",
(file->f_mode & FMODE_WRITE) ? "w" : "");

if (file->f_mode & FMODE_READ) {
if (!input_stream.buffers && audio_setup_buf(&input_stream))
return -ENOMEM;
poll_wait(file, &input_stream.buf->wait, wait);

for (i = 0; i input_stream.nbfrags; i++) {
if (input_stream.buffers[i].sem.count > 0){
mask |= POLLIN | POLLWRNORM;
break;
}
}
}

if (file->f_mode & FMODE_WRITE) {
if (!output_stream.buffers && audio_setup_buf(&output_stream))
return -ENOMEM;
poll_wait(file, &output_stream.buf->wait, wait);
for (i = 0; i output_stream.nbfrags; i++) {
if (output_stream.buffers[i].sem.count > 0){
mask |= POLLOUT | POLLWRNORM;
break;
}
}
}

DPRINTK("audio_poll() returned mask of %s\n",(mask & POLLOUT) ? "w" : "");

return mask;
}

ioctl:
根据oos audio programe guide完成相应功能

static int smdk2410_audio_ioctl(struct inode *inode, struct file *file,
uint cmd, ulong arg)
{
long val;

DPRINTK("smdk2410_audio_ioctl\n");

switch (cmd) {
case SNDCTL_DSP_SETFMT:
get_user(val, (long *) arg);
if (val & AUDIO_FMT_MASK) {
audio_fmt = val;
break;
} else
return -EINVAL;

case SNDCTL_DSP_CHANNELS:
case SNDCTL_DSP_STEREO:
get_user(val, (long *) arg);
if (cmd == SNDCTL_DSP_STEREO)
val = val ? 2 : 1;
if (val != 1 && val != 2)
return -EINVAL;
DPRINTK("audio_channels set to %d\n", val);
audio_channels = val;
break;

case SOUND_PCM_READ_CHANNELS:
DPRINTK("audio_channels is %d\n", audio_channels);
put_user(audio_channels, (long *) arg);
break;

case SNDCTL_DSP_SPEED:
get_user(val, (long *) arg);
val = audio_set_dsp_speed(val);
if (val 0)
return -EINVAL;
put_user(val, (long *) arg);
break;

case SOUND_PCM_READ_RATE:
put_user(audio_rate, (long *) arg);
break;

case SNDCTL_DSP_GETFMTS:
put_user(AUDIO_FMT_MASK, (long *) arg);
break;

case SNDCTL_DSP_GETBLKSIZE:
if(file->f_mode & FMODE_WRITE)
return put_user(audio_fragsize, (long *) arg);
else
return put_user(audio_fragsize, (int *) arg);

case SNDCTL_DSP_SETFRAGMENT:
if (file->f_mode & FMODE_WRITE) {
if (output_stream.buffers)
return -EBUSY;
get_user(val, (long *) arg);
audio_fragsize = 1 (val & 0xFFFF);
if (audio_fragsize 16)
audio_fragsize = 16;
if (audio_fragsize > 16384)
audio_fragsize = 16384;
audio_nbfrags = (val >> 16) & 0x7FFF;
if (audio_nbfrags 2)
audio_nbfrags = 2;
if (audio_nbfrags * audio_fragsize > 128 * 1024)
audio_nbfrags = 128 * 1024 / audio_fragsize;
if (audio_setup_buf(&output_stream))
return -ENOMEM;

}
if (file->f_mode & FMODE_READ) {
if (input_stream.buffers)
return -EBUSY;
get_user(val, (int *) arg);
audio_fragsize = 1 (val & 0xFFFF);
if (audio_fragsize 16)
audio_fragsize = 16;
if (audio_fragsize > 16384)
audio_fragsize = 16384;
audio_nbfrags = (val >> 16) & 0x7FFF;
if (audio_nbfrags 2)
audio_nbfrags = 2;
if (audio_nbfrags * audio_fragsize > 128 * 1024)
audio_nbfrags = 128 * 1024 / audio_fragsize;
if (audio_setup_buf(&input_stream))
return -ENOMEM;

}
break;

case SNDCTL_DSP_SYNC:
return audio_sync(file);

case SNDCTL_DSP_GETOSPACE:
{
audio_stream_t *s = &output_stream;
audio_buf_info *inf = (audio_buf_info *) arg;
int err = access_ok(VERIFY_WRITE, inf, sizeof(*inf));
int i;
int frags = 0, bytes = 0;

if (err)
return err;
for (i = 0; i s->nbfrags; i++) {
if (s->buffers[i].sem.count > 0) {
if (s->buffers[i].size == 0) frags++;
bytes += s->fragsize - s->buffers[i].size;
}
}
put_user(frags, &inf->fragments);
put_user(s->nbfrags, &inf->fragstotal);
put_user(s->fragsize, &inf->fragsize);
put_user(bytes, &inf->bytes);
break;
}

case SNDCTL_DSP_GETISPACE:
{
audio_stream_t *s = &input_stream;
audio_buf_info *inf = (audio_buf_info *) arg;
int err = access_ok(VERIFY_WRITE, inf, sizeof(*inf));
int i;
int frags = 0, bytes = 0;

if (!(file->f_mode & FMODE_READ))
return -EINVAL;

if (err)
return err;
for(i = 0; i s->nbfrags; i++){
if (s->buffers[i].sem.count > 0)
{
if (s->buffers[i].size == s->fragsize)
frags++;
bytes += s->buffers[i].size;
}
}
put_user(frags, &inf->fragments);
put_user(s->nbfrags, &inf->fragstotal);
put_user(s->fragsize, &inf->fragsize);
put_user(bytes, &inf->bytes);
break;
}

case SNDCTL_DSP_RESET:
if (file->f_mode & FMODE_READ) {
audio_clear_buf(&input_stream);
}
if (file->f_mode & FMODE_WRITE) {
audio_clear_buf(&output_stream);
}
return 0;

case SNDCTL_DSP_NONBLOCK:
file->f_flags |= O_NONBLOCK;
return 0;

case SNDCTL_DSP_POST:
case SNDCTL_DSP_SUBDIVIDE:
case SNDCTL_DSP_GETCAPS:
case SNDCTL_DSP_GETTRIGGER:
case SNDCTL_DSP_SETTRIGGER:
case SNDCTL_DSP_GETIPTR:
case SNDCTL_DSP_GETOPTR:
case SNDCTL_DSP_MAPINBUF:
case SNDCTL_DSP_MAPOUTBUF:
case SNDCTL_DSP_SETSYNCRO:
case SNDCTL_DSP_SETDUPLEX:
return -ENOSYS;
default:
return smdk2410_mixer_ioctl(inode, file, cmd, arg);
}

return 0;
}

open：
判断设备是否正忙->设置相关参数->初始化iis总线->清除缓冲区

static int smdk2410_audio_open(struct inode *inode, struct file *file)
{
int cold = !audio_active;

DPRINTK("audio_open\n");
if ((file->f_flags & O_ACCMODE) == O_RDONLY) {
if (audio_rd_refcount || audio_wr_refcount)
return -EBUSY;
audio_rd_refcount++;
} else if ((file->f_flags & O_ACCMODE) == O_WRONLY) {
if (audio_wr_refcount)
return -EBUSY;
audio_wr_refcount++;
} else if ((file->f_flags & O_ACCMODE) == O_RDWR) {
if (audio_rd_refcount || audio_wr_refcount)
return -EBUSY;
audio_rd_refcount++;
audio_wr_refcount++;
} else
return -EINVAL;

if (cold) {
audio_rate = AUDIO_RATE_DEFAULT;
audio_channels = AUDIO_CHANNELS_DEFAULT;
audio_fragsize = AUDIO_FRAGSIZE_DEFAULT;
audio_nbfrags = AUDIO_NBFRAGS_DEFAULT;
if ((file->f_mode & FMODE_WRITE)){
init_s3c2410_iis_bus_tx();//可写则初始化iis发送

audio_clear_buf(&output_stream);
}
if ((file->f_mode & FMODE_READ)){
init_s3c2410_iis_bus_rx();//可读则初始化iis接收

audio_clear_buf(&input_stream);
}
}
return 0;
}

release：
清除缓冲区，读写计数归0

static int smdk2410_audio_release(struct inode *inode, struct file *file)
{
DPRINTK("audio_release\n");

if (file->f_mode & FMODE_READ) {
if (audio_rd_refcount == 1)
audio_clear_buf(&input_stream);
audio_rd_refcount = 0;
}

if(file->f_mode & FMODE_WRITE) {
if (audio_wr_refcount == 1) {
audio_sync(file);
audio_clear_buf(&output_stream);
audio_wr_refcount = 0;
}
}

return 0;
}

mixer驱动：
fops结构体

static struct file_operations smdk2410_mixer_fops = {
ioctl: smdk2410_mixer_ioctl,
open: smdk2410_mixer_open,
release: smdk2410_mixer_release
};

ioctl：
同样根据oos audio programe guide完成相应功能，通过audio的ioctl调用

static int smdk2410_mixer_ioctl(struct inode *inode, struct file *file,
unsigned int cmd, unsigned long arg)
{
int ret;
long val = 0;

DPRINTK("smdk2410_mixer_ioctl\n");

switch (cmd) {
case SOUND_MIXER_INFO:
{
mixer_info info;
strncpy(info.id, "UDA1341", sizeof(info.id));
strncpy(info.name,"Philips UDA1341", sizeof(info.name));
info.modify_counter = audio_mix_modcnt;
return copy_to_user((void *)arg, &info, sizeof(info));
}

case SOUND_OLD_MIXER_INFO:
{
_old_mixer_info info;
strncpy(info.id, "UDA1341", sizeof(info.id));
strncpy(info.name,"Philips UDA1341", sizeof(info.name));
return copy_to_user((void *)arg, &info, sizeof(info));
}

case SOUND_MIXER_READ_STEREODEVS:
return put_user(0, (long *) arg);

case SOUND_MIXER_READ_CAPS:
val = SOUND_CAP_EXCL_INPUT;
return put_user(val, (long *) arg);

case SOUND_MIXER_WRITE_VOLUME:
ret = get_user(val, (long *) arg);
if (ret)
return ret;
uda1341_volume = 63 - (((val & 0xff) + 1) * 63) / 100;
uda1341_l3_address(UDA1341_REG_DATA0);
uda1341_l3_data(uda1341_volume);
break;

case SOUND_MIXER_READ_VOLUME:
val = ((63 - uda1341_volume) * 100) / 63;
val |= val 8;
return put_user(val, (long *) arg);

case SOUND_MIXER_READ_IGAIN:
val = ((31- mixer_igain) * 100) / 31;
return put_user(val, (int *) arg);

case SOUND_MIXER_WRITE_IGAIN:
ret = get_user(val, (int *) arg);
if (ret)
return ret;
mixer_igain = 31 - (val * 31 / 100);
/* use mixer gain channel 1*/
uda1341_l3_address(UDA1341_REG_DATA0);
uda1341_l3_data(EXTADDR(EXT0));
uda1341_l3_data(EXTDATA(EXT0_CH1_GAIN(mixer_igain)));
break;

default:
DPRINTK("mixer ioctl %u unknown\n", cmd);
return -ENOSYS;
}

open，release：
空函数，略
以上ioctl参考资料：
http://manuals.opensound.com/developer/ioctl.html

2，dma分析
(1)两个相关结构体：

buffer 结构:

typedef struct {
int size; /* buffer size */
char *start; /* point to actual buffer */
dma_addr_t dma_addr; /* physical buffer address */
struct semaphore sem; /* down before touching the buffer */
wait_queue_head_t wait;
int master; /* owner for buffer allocation, contain size when true */
} audio_buf_t;

内存块结构：

typedef struct {
audio_buf_t *buffers; /* pointer to audio buffer structures */
audio_buf_t *buf; /* current buffer used by read/write */
u_int buf_idx; /* index for the pointer above */
u_int fragsize; /* fragment i.e. buffer size */
u_int nbfrags; /* nbr of fragments */
dmach_t dma_ch; /* DMA channel (channel2 for audio) */
u_int dma_ok;
} audio_stream_t;

(2)dma使用过程：
首先是在probe函数中调用audio_init_dma初始化dma：

static int __init audio_init_dma(audio_stream_t * s, char *desc)
{
int ret ;
enum s3c2410_dmasrc source;
int hwcfg;
unsigned long devaddr;
int dcon;
unsigned int flags = 0;

DPRINTK("audio_init_dma\n");

if(s->dma_ch == DMA_CH2){//dma通道2初始化

source = S3C2410_DMASRC_MEM;
hwcfg = 3;
devaddr = 0x55000010;
dcon = (131) | (030) | (024);
flags = S3C2410_DMAF_AUTOSTART;

ret = s3c2410_dma_request(s->dma_ch, &s3c2410iis_dma_out, NULL);//为out申请dma通道

if (!ret & DMACH_LOW_LEVEL) {
printk(KERN_ERR "failed to get dma channel\n");
return ret;
}

//4个dma相关设置：device设置，传输设置，回调函数设置，标志设置

s3c2410_dma_devconfig(s->dma_ch, source, hwcfg, devaddr);
s3c2410_dma_config(s->dma_ch, 2, dcon);
s3c2410_dma_set_buffdone_fn(s->dma_ch, audio_dmaout_done_callback);
s3c2410_dma_setflags(s->dma_ch, flags);
s->dma_ok = 1;
return ret;
}
else if(s->dma_ch == DMA_CH1){
source =S3C2410_DMASRC_HW;
hwcfg =3;
devaddr = 0x55000010;
dcon = (131) | (123) | (224);
flags = S3C2410_DMAF_AUTOSTART;

ret = s3c2410_dma_request(s->dma_ch, &s3c2410iis_dma_in, NULL);//为in申请dma通道

if (!ret & DMACH_LOW_LEVEL) {
printk(KERN_ERR "failed to get dma channel\n");
return ret;
}

//同上，4个dma相关设置：device设置，传输设置，回调函数设置，标志设置

s3c2410_dma_devconfig(s->dma_ch, source, hwcfg, devaddr);
s3c2410_dma_config(s->dma_ch, 2, dcon);
s3c2410_dma_set_buffdone_fn(s->dma_ch, audio_dmain_done_callback);
s3c2410_dma_setflags(s->dma_ch, flags);
s->dma_ok =1;
return ret ;
}
else
return 1;
}

接着在读写函数中调用建audio_setup_buf立dma内存空间（读为in通道建立，写为out通道建立）：

static int audio_setup_buf(audio_stream_t * s)
{
int frag;
int dmasize = 0;
char *dmabuf = 0;
dma_addr_t dmaphys = 0;

DPRINTK("audio_setup_buf\n");
if (s->buffers)
return -EBUSY;

s->nbfrags = audio_nbfrags;
s->fragsize = audio_fragsize;

s->buffers = (audio_buf_t *)
kmalloc(sizeof(audio_buf_t) * s->nbfrags, GFP_KERNEL);//动态获得内存块空间

if (!s->buffers)
goto err;
memset(s->buffers, 0, sizeof(audio_buf_t) * s->nbfrags);

for (frag = 0; frag s->nbfrags; frag++) {//为内存块每个buffer建立dma映射

audio_buf_t *b = &s->buffers[frag];

if (!dmasize) {
dmasize = (s->nbfrags - frag) * s->fragsize;
do {
dmabuf = dma_alloc_coherent(NULL, dmasize, &dmaphys, GFP_KERNEL|GFP_DMA);//dma一致性映射建立，dmabuf指向开始处

if (!dmabuf)
dmasize -= s->fragsize;
} while (!dmabuf && dmasize);
if (!dmabuf)
goto err;
b->master = dmasize;
}

b->start = dmabuf;
b->dma_addr = dmaphys;
sema_init(&b->sem, 1);//初始化buffer信号量

DPRINTK("buf %d: start %p dma %d\n", frag, b->start, b->dma_addr);
init_waitqueue_head(&b->wait);//初始化buffer等待队列头

dmabuf += s->fragsize;//改变dma虚地址

dmaphys += s->fragsize;//改变dma总线地址

dmasize -= s->fragsize;//改变dma size

}

s->buf_idx = 0;
s->buf = &s->buffers[0];
return 0;

err:
printk(AUDIO_NAME ": unable to allocate audio memory\n ");
audio_clear_buf(s);
return -ENOMEM;
}

然后再使用int s3c2410_dma_enqueue(unsigned int channel, void *id,
dma_addr_t data, int size) 发起一次dma传输

最后传输结束后调用回调函数（内核调用）

static void audio_dmaout_done_callback(struct s3c2410_dma_chan *ch, void *buf, int size,
enum s3c2410_dma_buffresult result)
{
audio_buf_t *b = (audio_buf_t *) buf;

DPRINTK("audio_dmaout_done_callback\n");

up(&b->sem);
wake_up(&b->wait);
}

static void audio_dmain_done_callback(struct s3c2410_dma_chan *ch, void *buf, int size,
enum s3c2410_dma_buffresult result)
{
audio_buf_t *b = (audio_buf_t *) buf;

DPRINTK("audio_dmain_done_callback\n");

b->size = size;
up(&b->sem);
wake_up(&b->wait);
}

3，L3总线分析
uda1341 datasheet上的时序图：

地址：

驱动中的实现代码：

static void uda1341_l3_address(u8 data)
{
int i;
unsigned long flags;

local_irq_save(flags);

// write_gpio_bit(GPIO_L3MODE, 0);

s3c2410_gpio_setpin(S3C2410_GPB2,0);
// write_gpio_bit(GPIO_L3CLOCK, 1);

s3c2410_gpio_setpin(S3C2410_GPB4,1);
udelay(1);

for (i = 0; i 8; i++) {//从0位开始，按照时序图，逐位写入地址

if (data & 0x1) {
s3c2410_gpio_setpin(S3C2410_GPB4,0);
s3c2410_gpio_setpin(S3C2410_GPB3,1);
udelay(1);
s3c2410_gpio_setpin(S3C2410_GPB4,1);
} else {
s3c2410_gpio_setpin(S3C2410_GPB4,0);
s3c2410_gpio_setpin(S3C2410_GPB3,0);
udelay(1);
s3c2410_gpio_setpin(S3C2410_GPB4,1);
}
data >>= 1;
}

s3c2410_gpio_setpin(S3C2410_GPB2,1);
s3c2410_gpio_setpin(S3C2410_GPB4,1);
local_irq_restore(flags);
}

数据：

驱动中的实现代码：

static void uda1341_l3_data(u8 data)
{
int i;
unsigned long flags;

local_irq_save(flags);
udelay(1);

for (i = 0; i 8; i++) {
if (data & 0x1) {
s3c2410_gpio_setpin(S3C2410_GPB4,0);
s3c2410_gpio_setpin(S3C2410_GPB3,1);
udelay(1);
s3c2410_gpio_setpin(S3C2410_GPB4,1);
} else {
s3c2410_gpio_setpin(S3C2410_GPB4,0);
s3c2410_gpio_setpin(S3C2410_GPB3,0);
udelay(1);
s3c2410_gpio_setpin(S3C2410_GPB4,1);
}

data >>= 1;
}

local_irq_restore(flags);
}

向指定地址写入数据，总时序图：

L3总线简述：
首先写入地址，时序为 L3MODE置电平->L3CLOCK置高电平->L3CLOCK置低电平->写一位地址->延时->L3CLOCK置高电平->L3CLOCK置低电平，开始写地址下一位->...8位地址写完->L3MODE，L3CLOCK置高电平
然后开始写入数据，时序为 L3CLOCK置低电平->写一位数据->延时->L3CLOCK置高电平->L3CLOCK置低电平，开始写下一位数据->...8位数据写完，向之前写入的地址地址，一次写数据完成

功能：
通过向DATA0和STATUS两个寄存器写入数据，来控制uda1341。

4，iis总线分析
L3总线是用来控制uda1341的，iis总线则用来收发音频数据。
首先在probe函数中初始化iis总线：

static void init_s3c2410_iis_bus(void){
DPRINTK("init_s3c2410_iis_bus\n");
writel(0, iis_base + S3C2410_IISPSR);
writel(0, iis_base + S3C2410_IISCON);
writel(0, iis_base + S3C2410_IISMOD);
writel(0, iis_base + S3C2410_IISFCON);
clk_disable(iis_clock);
}

然后在open函数中，视打开方式来初始化iis总线（收、发）

static void init_s3c2410_iis_bus_rx(void)
{
unsigned int iiscon, iismod, iisfcon;
char *dstr;

DPRINTK("init_s3c2410_iis_bus_rx\n");
//Kill everything...

writel(0, iis_base + S3C2410_IISPSR);
writel(0, iis_base + S3C2410_IISCON);
writel(0, iis_base + S3C2410_IISMOD);
writel(0, iis_base + S3C2410_IISFCON);

clk_enable(iis_clock);

iiscon = iismod = iisfcon = 0;

//Setup basic stuff

iiscon |= S3C2410_IISCON_PSCEN; // Enable prescaler

iismod |= S3C2410_IISMOD_MASTER; // Set interface to Master Mode

iismod |= S3C2410_IISMOD_LR_LLOW; // Low for left channel

iismod |= S3C2410_IISMOD_MSB; // IIS format

iismod |= S3C2410_IISMOD_16BIT; // Serial data bit/channel is 16 bit

iismod |= S3C2410_IISMOD_384FS; // Master clock freq = 384 fs

iismod |= S3C2410_IISMOD_32FS; // 32 fs

iisfcon|= S3C2410_IISFCON_RXDMA | S3C2410_IISFCON_RXENABLE; //Set RX FIFO acces mode to DMA

//iisfcon|= S3C2410_IISFCON_TXDMA; //Set RX FIFO acces mode to DMA

iiscon |= S3C2410_IISCON_RXDMAEN | S3C2410_IISCON_IISEN; //Enable RX DMA service request

//iiscon |= S3C2410_IISCON_TXIDLE; //Set TX channel idle

iiscon &= (~S3C2410_IISCON_RXIDLE);

iismod |= S3C2410_IISMOD_RXMODE; //Set RX Mode

iismod |= S3C2410_IISMOD_TXMODE;
dstr="RX";
//setup the prescaler

audio_set_dsp_speed(audio_rate);

//iiscon has to be set last - it enables the interface

writel(iismod, iis_base + S3C2410_IISMOD);
writel(iisfcon, iis_base + S3C2410_IISFCON);
writel(iiscon, iis_base + S3C2410_IISCON);
}

static void init_s3c2410_iis_bus_tx(void)
{
unsigned int iiscon, iismod, iisfcon;
char *dstr;

DPRINTK("init_s3c2410_iis_bus_tx\n");
//Kill everything...

writel(0, iis_base + S3C2410_IISPSR);
writel(0, iis_base + S3C2410_IISCON);
writel(0, iis_base + S3C2410_IISMOD);
writel(0, iis_base + S3C2410_IISFCON);

clk_enable(iis_clock);

iiscon = iismod = iisfcon = 0;

//Setup basic stuff

iiscon |= S3C2410_IISCON_PSCEN; // Enable prescaler

iismod |= S3C2410_IISMOD_MASTER; // Set interface to Master Mode

iismod |= S3C2410_IISMOD_LR_LLOW; // Low for left channel

iismod |= S3C2410_IISMOD_MSB; // MSB format

iismod |= S3C2410_IISMOD_16BIT; // Serial data bit/channel is 16 bit

iismod |= S3C2410_IISMOD_384FS; // Master clock freq = 384 fs

iismod |= S3C2410_IISMOD_32FS; // 32 fs

iisfcon|= S3C2410_IISFCON_RXDMA; //Set RX FIFO acces mode to DMA

iisfcon|= S3C2410_IISFCON_TXDMA; //Set TX FIFO acces mode to DMA

iiscon |= S3C2410_IISCON_TXDMAEN | S3C2410_IISCON_IISEN; //Enable TX DMA service request

//iiscon |= S3C2410_IISCON_RXIDLE; //Set RX channel idle

iiscon &= ~S3C2410_IISCON_TXIDLE;
iismod |= S3C2410_IISMOD_TXMODE; //Set TX Mode

iismod |= S3C2410_IISMOD_RXMODE;
iisfcon|= S3C2410_IISFCON_TXENABLE; //Enable TX Fifo

dstr="TX";

//setup the prescaler

audio_set_dsp_speed(audio_rate);

//iiscon has to be set last - it enables the interface

writel(iismod, iis_base + S3C2410_IISMOD);
writel(iisfcon, iis_base + S3C2410_IISFCON);
writel(iiscon, iis_base + S3C2410_IISCON);
}

文章来自

http://blogold.chinaunix.net/u3/97285/showart_1979063.html

s3c2440 uda1341声卡驱动分析（oos）

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