audio.c

讲述linux的初始化过程

/*
 * sound/audio.c
 *
 * Device file manager for /dev/audio
 */

/*
 * Copyright (C) by Hannu Savolainen 1993-1997
 *
 * OSS/Free for Linux is distributed under the GNU GENERAL PUBLIC LICENSE (GPL)
 * Version 2 (June 1991). See the "COPYING" file distributed with this software
 * for more info.
 */
/*
 * Thomas Sailer   : ioctl code reworked (vmalloc/vfree removed)
 * Thomas Sailer   : moved several static variables into struct audio_operations
 *                   (which is grossly misnamed btw.) because they have the same
 *                   lifetime as the rest in there and dynamic allocation saves
 *                   12k or so
 * Thomas Sailer   : use more logical O_NONBLOCK semantics
 * Daniel Rodriksson: reworked the use of the device specific copy_user
 *                    still generic
 * Horst von Brand:  Add missing #include <linux/string.h>
 */

#include <linux/stddef.h>
#include <linux/string.h>
#include <linux/kmod.h>

#include "sound_config.h"
#include "ulaw.h"
#include "coproc.h"

#define NEUTRAL8	0x80
#define NEUTRAL16	0x00


int             dma_ioctl(int dev, unsigned int cmd, caddr_t arg);

static int set_format(int dev, int fmt)
{
	if (fmt != AFMT_QUERY)
	{
		audio_devs[dev]->local_conversion = 0;

		if (!(audio_devs[dev]->format_mask & fmt))	/* Not supported */
		{
			if (fmt == AFMT_MU_LAW)
			{
				fmt = AFMT_U8;
				audio_devs[dev]->local_conversion = CNV_MU_LAW;
			}
			else
				fmt = AFMT_U8;	/* This is always supported */
		}
		audio_devs[dev]->audio_format = audio_devs[dev]->d->set_bits(dev, fmt);
		audio_devs[dev]->local_format = fmt;
	}
	else
		return audio_devs[dev]->local_format;

	if (audio_devs[dev]->local_conversion)
		return audio_devs[dev]->local_conversion;
	else 
		return audio_devs[dev]->local_format;
}

int audio_open(int dev, struct file *file)
{
	int ret;
	int bits;
	int dev_type = dev & 0x0f;
	int mode = translate_mode(file);

	dev = dev >> 4;

	if (dev_type == SND_DEV_DSP16)
		bits = 16;
	else
		bits = 8;

	if (dev < 0 || dev >= num_audiodevs)
		return -ENXIO;

	if (audio_devs[dev]->d->owner)
		__MOD_INC_USE_COUNT (audio_devs[dev]->d->owner);

	if ((ret = DMAbuf_open(dev, mode)) < 0)
		return ret;

	if (audio_devs[dev]->coproc) {
		if ((ret = audio_devs[dev]->coproc->
			open(audio_devs[dev]->coproc->devc, COPR_PCM)) < 0) {
			audio_release(dev, file);
			printk(KERN_WARNING "Sound: Can't access coprocessor device\n");
			return ret;
		}
	}
	
	audio_devs[dev]->local_conversion = 0;

	if (dev_type == SND_DEV_AUDIO)
		set_format(dev, AFMT_MU_LAW);
	else 
		set_format(dev, bits);

	audio_devs[dev]->audio_mode = AM_NONE;


	return ret;
}

static void sync_output(int dev)
{
	int             p, i;
	int             l;
	struct dma_buffparms *dmap = audio_devs[dev]->dmap_out;

	if (dmap->fragment_size <= 0)
		return;
	dmap->flags |= DMA_POST;

	/* Align the write pointer with fragment boundaries */
	
	if ((l = dmap->user_counter % dmap->fragment_size) > 0)
	{
		int len;
		unsigned long offs = dmap->user_counter % dmap->bytes_in_use;

		len = dmap->fragment_size - l;
		memset(dmap->raw_buf + offs, dmap->neutral_byte, len);
		DMAbuf_move_wrpointer(dev, len);
	}
	
	/*
	 * Clean all unused buffer fragments.
	 */

	p = dmap->qtail;
	dmap->flags |= DMA_POST;

	for (i = dmap->qlen + 1; i < dmap->nbufs; i++)
	{
		p = (p + 1) % dmap->nbufs;
		if (((dmap->raw_buf + p * dmap->fragment_size) + dmap->fragment_size) >
			(dmap->raw_buf + dmap->buffsize))
				printk(KERN_ERR "audio: Buffer error 2\n");

		memset(dmap->raw_buf + p * dmap->fragment_size,
			dmap->neutral_byte,
			dmap->fragment_size);
	}

	dmap->flags |= DMA_DIRTY;
}

void audio_release(int dev, struct file *file)
{
	int             mode = translate_mode(file);

	dev = dev >> 4;

	/*
	 * We do this in DMAbuf_release(). Why are we doing it
	 * here? Why don't we test the file mode before setting
	 * both flags? DMAbuf_release() does.
	 * ...pester...pester...pester...
	 */
	audio_devs[dev]->dmap_out->closing = 1;
	audio_devs[dev]->dmap_in->closing = 1;

	/*
	 * We need to make sure we allocated the dmap_out buffer
	 * before we go mucking around with it in sync_output().
	 */
	if (mode & OPEN_WRITE)
		sync_output(dev);

	if (audio_devs[dev]->coproc)
		audio_devs[dev]->coproc->close(audio_devs[dev]->coproc->devc, COPR_PCM);
	DMAbuf_release(dev, mode);

	if (audio_devs[dev]->d->owner)
		__MOD_DEC_USE_COUNT (audio_devs[dev]->d->owner);
}

static void translate_bytes(const unsigned char *table, unsigned char *buff, int n)
{
	unsigned long   i;

	if (n <= 0)
		return;

	for (i = 0; i < n; ++i)
		buff[i] = table[buff[i]];
}

int audio_write(int dev, struct file *file, const char *buf, int count)
{
	int c, p, l, buf_size, used, returned;
	int err;
	char *dma_buf;

	dev = dev >> 4;

	p = 0;
	c = count;
	
	if(count < 0)
		return -EINVAL;

	if (!(audio_devs[dev]->open_mode & OPEN_WRITE))
		return -EPERM;

	if (audio_devs[dev]->flags & DMA_DUPLEX)
		audio_devs[dev]->audio_mode |= AM_WRITE;
	else
		audio_devs[dev]->audio_mode = AM_WRITE;

	if (!count)		/* Flush output */
	{
		  sync_output(dev);
		  return 0;
	}
	
	while (c)
	{
		if ((err = DMAbuf_getwrbuffer(dev, &dma_buf, &buf_size, !!(file->f_flags & O_NONBLOCK))) < 0)
		{
			    /* Handle nonblocking mode */
			if ((file->f_flags & O_NONBLOCK) && err == -EAGAIN)
				return p? p : -EAGAIN;	/* No more space. Return # of accepted bytes */
			return err;
		}
		l = c;

		if (l > buf_size)
			l = buf_size;

		returned = l;
		used = l;
		if (!audio_devs[dev]->d->copy_user)
		{
			if ((dma_buf + l) >
				(audio_devs[dev]->dmap_out->raw_buf + audio_devs[dev]->dmap_out->buffsize))
			{
				printk(KERN_ERR "audio: Buffer error 3 (%lx,%d), (%lx, %d)\n", (long) dma_buf, l, (long) audio_devs[dev]->dmap_out->raw_buf, (int) audio_devs[dev]->dmap_out->buffsize);
				return -EDOM;
			}
			if (dma_buf < audio_devs[dev]->dmap_out->raw_buf)
			{
				printk(KERN_ERR "audio: Buffer error 13 (%lx<%lx)\n", (long) dma_buf, (long) audio_devs[dev]->dmap_out->raw_buf);
				return -EDOM;
			}
			if(copy_from_user(dma_buf, &(buf)[p], l))
				return -EFAULT;
		} 
		else audio_devs[dev]->d->copy_user (dev,
						dma_buf, 0,
						buf, p,
						c, buf_size,
						&used, &returned,
						l);
		l = returned;

		if (audio_devs[dev]->local_conversion & CNV_MU_LAW)
		{
			/*
			 * This just allows interrupts while the conversion is running
			 */
			sti();
			translate_bytes(ulaw_dsp, (unsigned char *) dma_buf, l);
		}
		c -= used;
		p += used;
		DMAbuf_move_wrpointer(dev, l);

	}

	return count;
}

int audio_read(int dev, struct file *file, char *buf, int count)
{
	int             c, p, l;
	char           *dmabuf;
	int             buf_no;

	dev = dev >> 4;
	p = 0;
	c = count;

	if (!(audio_devs[dev]->open_mode & OPEN_READ))
		return -EPERM;

	if ((audio_devs[dev]->audio_mode & AM_WRITE) && !(audio_devs[dev]->flags & DMA_DUPLEX))
		sync_output(dev);

	if (audio_devs[dev]->flags & DMA_DUPLEX)
		audio_devs[dev]->audio_mode |= AM_READ;
	else
		audio_devs[dev]->audio_mode = AM_READ;

	while(c)
	{
		if ((buf_no = DMAbuf_getrdbuffer(dev, &dmabuf, &l, !!(file->f_flags & O_NONBLOCK))) < 0)
		{
			/*
			 *	Nonblocking mode handling. Return current # of bytes
			 */

			if (p > 0) 		/* Avoid throwing away data */
				return p;	/* Return it instead */

			if ((file->f_flags & O_NONBLOCK) && buf_no == -EAGAIN)
				return -EAGAIN;

			return buf_no;
		}
		if (l > c)
			l = c;

		/*
		 * Insert any local processing here.
		 */

		if (audio_devs[dev]->local_conversion & CNV_MU_LAW)
		{
			/*
			 * This just allows interrupts while the conversion is running
			 */
			sti();

			translate_bytes(dsp_ulaw, (unsigned char *) dmabuf, l);
		}
		
		{
			char           *fixit = dmabuf;

			if(copy_to_user(&(buf)[p], fixit, l))
				return -EFAULT;
		};

		DMAbuf_rmchars(dev, buf_no, l);

		p += l;
		c -= l;
	}

	return count - c;
}

int audio_ioctl(int dev, struct file *file, unsigned int cmd, caddr_t arg)
{
	int val, count;
	unsigned long flags;
	struct dma_buffparms *dmap;

	dev = dev >> 4;

	if (_IOC_TYPE(cmd) == 'C')	{
		if (audio_devs[dev]->coproc)	/* Coprocessor ioctl */
			return audio_devs[dev]->coproc->ioctl(audio_devs[dev]->coproc->devc, cmd, arg, 0);
		/* else
		        printk(KERN_DEBUG"/dev/dsp%d: No coprocessor for this device\n", dev); */
		return -ENXIO;
	}
	else switch (cmd) 
	{
		case SNDCTL_DSP_SYNC:
			if (!(audio_devs[dev]->open_mode & OPEN_WRITE))
				return 0;
			if (audio_devs[dev]->dmap_out->fragment_size == 0)
				return 0;
			sync_output(dev);
			DMAbuf_sync(dev);
			DMAbuf_reset(dev);
			return 0;

		case SNDCTL_DSP_POST:
			if (!(audio_devs[dev]->open_mode & OPEN_WRITE))
				return 0;
			if (audio_devs[dev]->dmap_out->fragment_size == 0)
				return 0;
			audio_devs[dev]->dmap_out->flags |= DMA_POST | DMA_DIRTY;
			sync_output(dev);
			dma_ioctl(dev, SNDCTL_DSP_POST, (caddr_t) 0);
			return 0;

		case SNDCTL_DSP_RESET:
			audio_devs[dev]->audio_mode = AM_NONE;
			DMAbuf_reset(dev);
			return 0;

		case SNDCTL_DSP_GETFMTS:
			val = audio_devs[dev]->format_mask | AFMT_MU_LAW;
			break;
	
		case SNDCTL_DSP_SETFMT:
			if (get_user(val, (int *)arg))
				return -EFAULT;
			val = set_format(dev, val);
			break;

		case SNDCTL_DSP_GETISPACE:
			if (!(audio_devs[dev]->open_mode & OPEN_READ))
				return 0;
  			if ((audio_devs[dev]->audio_mode & AM_WRITE) && !(audio_devs[dev]->flags & DMA_DUPLEX))
  				return -EBUSY;
			return dma_ioctl(dev, cmd, arg);

		case SNDCTL_DSP_GETOSPACE:
			if (!(audio_devs[dev]->open_mode & OPEN_WRITE))
				return -EPERM;
  			if ((audio_devs[dev]->audio_mode & AM_READ) && !(audio_devs[dev]->flags & DMA_DUPLEX))
  				return -EBUSY;
			return dma_ioctl(dev, cmd, arg);
		
		case SNDCTL_DSP_NONBLOCK:
			file->f_flags |= O_NONBLOCK;
			return 0;

		case SNDCTL_DSP_GETCAPS:
				val = 1 | DSP_CAP_MMAP;	/* Revision level of this ioctl() */
				if (audio_devs[dev]->flags & DMA_DUPLEX &&
					audio_devs[dev]->open_mode == OPEN_READWRITE)
					val |= DSP_CAP_DUPLEX;
				if (audio_devs[dev]->coproc)
					val |= DSP_CAP_COPROC;
				if (audio_devs[dev]->d->local_qlen)	/* Device has hidden buffers */
					val |= DSP_CAP_BATCH;
				if (audio_devs[dev]->d->trigger)	/* Supports SETTRIGGER */
					val |= DSP_CAP_TRIGGER;
				break;
			
		case SOUND_PCM_WRITE_RATE:
			if (get_user(val, (int *)arg))
				return -EFAULT;
			val = audio_devs[dev]->d->set_speed(dev, val);
			break;

		case SOUND_PCM_READ_RATE:
			val = audio_devs[dev]->d->set_speed(dev, 0);
			break;
			
		case SNDCTL_DSP_STEREO:
			if (get_user(val, (int *)arg))
				return -EFAULT;
			if (val > 1 || val < 0)
				return -EINVAL;
			val = audio_devs[dev]->d->set_channels(dev, val + 1) - 1;
			break;

		case SOUND_PCM_WRITE_CHANNELS:
			if (get_user(val, (int *)arg))
				return -EFAULT;
			val = audio_devs[dev]->d->set_channels(dev, val);
			break;

		case SOUND_PCM_READ_CHANNELS:
			val = audio_devs[dev]->d->set_channels(dev, 0);
			break;
		
		case SOUND_PCM_READ_BITS:
			val = audio_devs[dev]->d->set_bits(dev, 0);
			break;

		case SNDCTL_DSP_SETDUPLEX:
			if (audio_devs[dev]->open_mode != OPEN_READWRITE)
				return -EPERM;
			return (audio_devs[dev]->flags & DMA_DUPLEX) ? 0 : -EIO;

		case SNDCTL_DSP_PROFILE:
			if (get_user(val, (int *)arg))
				return -EFAULT;
			if (audio_devs[dev]->open_mode & OPEN_WRITE)
				audio_devs[dev]->dmap_out->applic_profile = val;
			if (audio_devs[dev]->open_mode & OPEN_READ)
				audio_devs[dev]->dmap_in->applic_profile = val;
			return 0;