s3c2440 uda1341声卡驱动分析（oos） (2011-03-10 12:56)转载

s3c2440 uda1341声卡驱动分析（oos） (2011-03-10 12:56)转载
标签: 声卡驱动 分类：

音、视频驱动
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 = (1<<31) | (0<<30) | (0<<24); 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 = (1<<31) | (1<<23) | (2<<24); 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：

[align=center]<IMG src="http://blogimg.chinaunix.net/blog/upfile2/090627173501.jpg" width=500 onload="javascript:if(this.width>500)this.width=500;" border=0>[/align]
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：

[align=center]<IMG src="http://blogimg.chinaunix.net/blog/upfile2/090627173710.jpg" width=500 onload="javascript:if(this.width>500)this.width=500;" border=0>[/align]

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：

[align=center]<IMG src="http://blogimg.chinaunix.net/blog/upfile2/090627180823.jpg" width=500 onload="javascript:if(this.width>500)this.width=500;" border=0>[/align]

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