===================================================================
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;
}
static int __init audio_init_dma(audio_stream_t * s, char *desc)
{
int ret ;
s3c2410_dmasrc_t source;
int hwcfg;
unsigned long devaddr;
dmach_t channel;
int dcon;
unsigned int flags = 0;
if(s->dma_ch == DMA_CH2){
channel = 2;
source = S3C2410_DMASRC_MEM;
hwcfg = 3;
devaddr = 0x55000010;
dcon = 0xa0800000;
flags = S3C2410_DMAF_AUTOSTART;
ret = s3c2410_dma_request(s->dma_ch, &s3c2410iis_dma_out, NULL);
s3c2410_dma_devconfig(channel, source, hwcfg, devaddr);
s3c2410_dma_config(channel, 2, dcon);
s3c2410_dma_set_buffdone_fn(channel, audio_dmaout_done_callback);
s3c2410_dma_setflags(channel, flags);
s->dma_ok = 1;
return ret;
}
else if(s->dma_ch == DMA_CH1){
channel =1;
source =S3C2410_DMASRC_HW;
hwcfg =3;
devaddr = 0x55000010;
dcon = 0xa2900000;
flags = S3C2410_DMAF_AUTOSTART;
ret = s3c2410_dma_request(s->dma_ch, &s3c2410iis_dma_in, NULL);
s3c2410_dma_devconfig(channel, source, hwcfg, devaddr);
s3c2410_dma_config(channel, 2, dcon);
s3c2410_dma_set_buffdone_fn(channel, audio_dmain_done_callback);
s3c2410_dma_setflags(channel, flags);
s->dma_ok =1;
return ret ;
}
else
return 1;
}
小弟搞uda1341的录音部分已多时,现在终于可以正常播音、录音了，现把驱程公开，希望对正在为此问题烦恼的朋友有所帮助^_^
首先说明一下：
1、 驱程源于中国linux公社->嵌入式linux2.6内核专题：
上的牛貼，稍加修改就可以使用madplay正常播放mp3，但它提供的源码录音部分没做好。
2、 小弟参考网上其它大虾的讨论和三星、uda1341的datasheet修改了驱动程序（见红色部分），其中smdk2410_audio_read函数中注释了：
if (ppos != &file->f_pos)
return -ESPIPE;
部分是因为此处会造成死锁的现象，也就是经常在网上看到的：
cat: Read error: Illegal seek
3、 按照第2步修改了驱动程序后还是不行，出现：
dma1: loadbuffer:timeout loading buffer
的错误，一直没搞清楚为什么。
最后，参考华恒提供的uda13800驱程，修改了dcon寄存器的配置（如蓝色部分），困扰了我一个月的问题终于解决了^_^
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