audio.c

USB Audio Class Driver

		x >>= 16;
		r += 16;
	}
	if (x >= 0x100) {
		x >>= 8;
		r += 8;
	}
	if (x >= 0x10) {
		x >>= 4;
		r += 4;
	}
	if (x >= 4) {
		x >>= 2;
		r += 2;
	}
	if (x >= 2)
		r++;
	return r;
}

/* --------------------------------------------------------------------- */

/*
 * OSS compatible ring buffer management. The ring buffer may be mmap'ed into
 * an application address space.
 *
 * I first used the rvmalloc stuff copied from bttv. Alan Cox did not like it, so
 * we now use an array of pointers to a single page each. This saves us the
 * kernel page table manipulations, but we have to do a page table alike mechanism
 * (though only one indirection) in software.
 */

static void dmabuf_release(struct dmabuf *db)
{
	unsigned int nr;
	void *p;

	for(nr = 0; nr < NRSGBUF; nr++) {
		if (!(p = db->sgbuf[nr]))
			continue;
		ClearPageReserved(virt_to_page(p));
		free_page((unsigned long)p);
		db->sgbuf[nr] = NULL;
	}
	db->mapped = db->ready = 0;
}

static int dmabuf_init(struct dmabuf *db)
{
	unsigned int nr, bytepersec, bufs;
	void *p;

	/* initialize some fields */
	db->rdptr = db->wrptr = db->total_bytes = db->count = db->error = 0;
	/* calculate required buffer size */
	bytepersec = db->srate << AFMT_BYTESSHIFT(db->format);
	bufs = 1U << DMABUFSHIFT;
	if (db->ossfragshift) {
		if ((1000 << db->ossfragshift) < bytepersec)
			db->fragshift = ld2(bytepersec/1000);
		else
			db->fragshift = db->ossfragshift;
	} else {
		db->fragshift = ld2(bytepersec/100/(db->subdivision ? db->subdivision : 1));
		if (db->fragshift < 3)
			db->fragshift = 3;
	}
	db->numfrag = bufs >> db->fragshift;
	while (db->numfrag < 4 && db->fragshift > 3) {
		db->fragshift--;
		db->numfrag = bufs >> db->fragshift;
	}
	db->fragsize = 1 << db->fragshift;
	if (db->ossmaxfrags >= 4 && db->ossmaxfrags < db->numfrag)
		db->numfrag = db->ossmaxfrags;
	db->dmasize = db->numfrag << db->fragshift;
	for(nr = 0; nr < NRSGBUF; nr++) {
		if (!db->sgbuf[nr]) {
			p = (void *)get_zeroed_page(GFP_KERNEL);
			if (!p)
				return -ENOMEM;
			db->sgbuf[nr] = p;
			SetPageReserved(virt_to_page(p));
		}
		memset(db->sgbuf[nr], AFMT_ISUNSIGNED(db->format) ? 0x80 : 0, PAGE_SIZE);
		if ((nr << PAGE_SHIFT) >= db->dmasize)
			break;
	}
	db->bufsize = nr << PAGE_SHIFT;
	db->ready = 1;
	dprintk((KERN_DEBUG "usbaudio: dmabuf_init bytepersec %d bufs %d ossfragshift %d ossmaxfrags %d "
	         "fragshift %d fragsize %d numfrag %d dmasize %d bufsize %d fmt 0x%x srate %d\n",
	         bytepersec, bufs, db->ossfragshift, db->ossmaxfrags, db->fragshift, db->fragsize,
	         db->numfrag, db->dmasize, db->bufsize, db->format, db->srate));
	return 0;
}

static int dmabuf_mmap(struct vm_area_struct *vma, struct dmabuf *db, unsigned long start, unsigned long size, pgprot_t prot)
{
	unsigned int nr;

	if (!db->ready || db->mapped || (start | size) & (PAGE_SIZE-1) || size > db->bufsize)
		return -EINVAL;
	size >>= PAGE_SHIFT;
	for(nr = 0; nr < size; nr++)
		if (!db->sgbuf[nr])
			return -EINVAL;
	db->mapped = 1;
	for(nr = 0; nr < size; nr++) {
		unsigned long pfn;

		pfn = virt_to_phys(db->sgbuf[nr]) >> PAGE_SHIFT;
		if (remap_pfn_range(vma, start, pfn, PAGE_SIZE, prot))
			return -EAGAIN;
		start += PAGE_SIZE;
	}
	return 0;
}

static void dmabuf_copyin(struct dmabuf *db, const void *buffer, unsigned int size)
{
	unsigned int pgrem, rem;

	db->total_bytes += size;
	for (;;) {
		if (size <= 0)
			return;
		pgrem = ((~db->wrptr) & (PAGE_SIZE-1)) + 1;
		if (pgrem > size)
			pgrem = size;
		rem = db->dmasize - db->wrptr;
		if (pgrem > rem)
			pgrem = rem;
		memcpy((db->sgbuf[db->wrptr >> PAGE_SHIFT]) + (db->wrptr & (PAGE_SIZE-1)), buffer, pgrem);
		size -= pgrem;
		buffer += pgrem;
		db->wrptr += pgrem;
		if (db->wrptr >= db->dmasize)
			db->wrptr = 0;
	}
}

static void dmabuf_copyout(struct dmabuf *db, void *buffer, unsigned int size)
{
	unsigned int pgrem, rem;

	db->total_bytes += size;
	for (;;) {
		if (size <= 0)
			return;
		pgrem = ((~db->rdptr) & (PAGE_SIZE-1)) + 1;
		if (pgrem > size)
			pgrem = size;
		rem = db->dmasize - db->rdptr;
		if (pgrem > rem)
			pgrem = rem;
		memcpy(buffer, (db->sgbuf[db->rdptr >> PAGE_SHIFT]) + (db->rdptr & (PAGE_SIZE-1)), pgrem);
		size -= pgrem;
		buffer += pgrem;
		db->rdptr += pgrem;
		if (db->rdptr >= db->dmasize)
			db->rdptr = 0;
	}
}

static int dmabuf_copyin_user(struct dmabuf *db, unsigned int ptr, const void __user *buffer, unsigned int size)
{
	unsigned int pgrem, rem;

	if (!db->ready || db->mapped)
		return -EINVAL;
	for (;;) {
		if (size <= 0)
			return 0;
		pgrem = ((~ptr) & (PAGE_SIZE-1)) + 1;
		if (pgrem > size)
			pgrem = size;
		rem = db->dmasize - ptr;
		if (pgrem > rem)
			pgrem = rem;
		if (copy_from_user((db->sgbuf[ptr >> PAGE_SHIFT]) + (ptr & (PAGE_SIZE-1)), buffer, pgrem))
			return -EFAULT;
		size -= pgrem;
		buffer += pgrem;
		ptr += pgrem;
		if (ptr >= db->dmasize)
			ptr = 0;
	}
}

static int dmabuf_copyout_user(struct dmabuf *db, unsigned int ptr, void __user *buffer, unsigned int size)
{
	unsigned int pgrem, rem;

	if (!db->ready || db->mapped)
		return -EINVAL;
	for (;;) {
		if (size <= 0)
			return 0;
		pgrem = ((~ptr) & (PAGE_SIZE-1)) + 1;
		if (pgrem > size)
			pgrem = size;
		rem = db->dmasize - ptr;
		if (pgrem > rem)
			pgrem = rem;
		if (copy_to_user(buffer, (db->sgbuf[ptr >> PAGE_SHIFT]) + (ptr & (PAGE_SIZE-1)), pgrem))
			return -EFAULT;
		size -= pgrem;
		buffer += pgrem;
		ptr += pgrem;
		if (ptr >= db->dmasize)
			ptr = 0;
	}
}

/* --------------------------------------------------------------------- */
/*
 * USB I/O code. We do sample format conversion if necessary
 */

static void usbin_stop(struct usb_audiodev *as)
{
	struct usbin *u = &as->usbin;
	unsigned long flags;
	unsigned int i, notkilled = 1;

	spin_lock_irqsave(&as->lock, flags);
	u->flags &= ~FLG_RUNNING;
	i = u->flags;
	spin_unlock_irqrestore(&as->lock, flags);
	while (i & (FLG_URB0RUNNING|FLG_URB1RUNNING|FLG_SYNC0RUNNING|FLG_SYNC1RUNNING)) {
		set_current_state(notkilled ? TASK_INTERRUPTIBLE : TASK_UNINTERRUPTIBLE);
		schedule_timeout(1);
		spin_lock_irqsave(&as->lock, flags);
		i = u->flags;
		spin_unlock_irqrestore(&as->lock, flags);
		if (notkilled && signal_pending(current)) {
			if (i & FLG_URB0RUNNING)
				usb_kill_urb(u->durb[0].urb);
			if (i & FLG_URB1RUNNING)
				usb_kill_urb(u->durb[1].urb);
			if (i & FLG_SYNC0RUNNING)
				usb_kill_urb(u->surb[0].urb);
			if (i & FLG_SYNC1RUNNING)
				usb_kill_urb(u->surb[1].urb);
			notkilled = 0;
		}
	}
	set_current_state(TASK_RUNNING);
	if (u->durb[0].urb->transfer_buffer)
		kfree(u->durb[0].urb->transfer_buffer);
	if (u->durb[1].urb->transfer_buffer)
		kfree(u->durb[1].urb->transfer_buffer);
	if (u->surb[0].urb->transfer_buffer)
		kfree(u->surb[0].urb->transfer_buffer);
	if (u->surb[1].urb->transfer_buffer)
		kfree(u->surb[1].urb->transfer_buffer);
	u->durb[0].urb->transfer_buffer = u->durb[1].urb->transfer_buffer = 
		u->surb[0].urb->transfer_buffer = u->surb[1].urb->transfer_buffer = NULL;
}

static inline void usbin_release(struct usb_audiodev *as)
{
	usbin_stop(as);
}

static void usbin_disc(struct usb_audiodev *as)
{
	struct usbin *u = &as->usbin;

	unsigned long flags;

	spin_lock_irqsave(&as->lock, flags);
	u->flags &= ~(FLG_RUNNING | FLG_CONNECTED);
	spin_unlock_irqrestore(&as->lock, flags);
	usbin_stop(as);
}

static void conversion(const void *ibuf, unsigned int ifmt, void *obuf, unsigned int ofmt, void *tmp, unsigned int scnt)
{
	unsigned int cnt, i;
	__s16 *sp, *sp2, s;
	unsigned char *bp;

	cnt = scnt;
	if (AFMT_ISSTEREO(ifmt))
		cnt <<= 1;
	sp = ((__s16 *)tmp) + cnt;
	switch (ifmt & ~AFMT_STEREO) {
	case AFMT_U8:
		for (bp = ((unsigned char *)ibuf)+cnt, i = 0; i < cnt; i++) {
			bp--;
			sp--;
			*sp = (*bp ^ 0x80) << 8;
		}
		break;
			
	case AFMT_S8:
		for (bp = ((unsigned char *)ibuf)+cnt, i = 0; i < cnt; i++) {
			bp--;
			sp--;
			*sp = *bp << 8;
		}
		break;
		
	case AFMT_U16_LE:
		for (bp = ((unsigned char *)ibuf)+2*cnt, i = 0; i < cnt; i++) {
			bp -= 2;
			sp--;
			*sp = (bp[0] | (bp[1] << 8)) ^ 0x8000;
		}
		break;

	case AFMT_U16_BE:
		for (bp = ((unsigned char *)ibuf)+2*cnt, i = 0; i < cnt; i++) {
			bp -= 2;
			sp--;
			*sp = (bp[1] | (bp[0] << 8)) ^ 0x8000;
		}
		break;

	case AFMT_S16_LE:
		for (bp = ((unsigned char *)ibuf)+2*cnt, i = 0; i < cnt; i++) {
			bp -= 2;
			sp--;
			*sp = bp[0] | (bp[1] << 8);
		}
		break;

	case AFMT_S16_BE:
		for (bp = ((unsigned char *)ibuf)+2*cnt, i = 0; i < cnt; i++) {
			bp -= 2;
			sp--;
			*sp = bp[1] | (bp[0] << 8);
		}
		break;
	}
	if (!AFMT_ISSTEREO(ifmt) && AFMT_ISSTEREO(ofmt)) {
		/* expand from mono to stereo */
		for (sp = ((__s16 *)tmp)+scnt, sp2 = ((__s16 *)tmp)+2*scnt, i = 0; i < scnt; i++) {
			sp--;
			sp2 -= 2;
			sp2[0] = sp2[1] = sp[0];
		}
	}
	if (AFMT_ISSTEREO(ifmt) && !AFMT_ISSTEREO(ofmt)) {
		/* contract from stereo to mono */
		for (sp = sp2 = ((__s16 *)tmp), i = 0; i < scnt; i++, sp++, sp2 += 2)
			sp[0] = (sp2[0] + sp2[1]) >> 1;
	}
	cnt = scnt;
	if (AFMT_ISSTEREO(ofmt))
		cnt <<= 1;
	sp = ((__s16 *)tmp);
	bp = ((unsigned char *)obuf);
	switch (ofmt & ~AFMT_STEREO) {
	case AFMT_U8:
		for (i = 0; i < cnt; i++, sp++, bp++)
			*bp = (*sp >> 8) ^ 0x80;
		break;

	case AFMT_S8:
		for (i = 0; i < cnt; i++, sp++, bp++)
			*bp = *sp >> 8;
		break;

	case AFMT_U16_LE:
		for (i = 0; i < cnt; i++, sp++, bp += 2) {
			s = *sp;
			bp[0] = s;
			bp[1] = (s >> 8) ^ 0x80;
		}
		break;

	case AFMT_U16_BE:
		for (i = 0; i < cnt; i++, sp++, bp += 2) {
			s = *sp;
			bp[1] = s;
			bp[0] = (s >> 8) ^ 0x80;
		}
		break;

	case AFMT_S16_LE:
		for (i = 0; i < cnt; i++, sp++, bp += 2) {
			s = *sp;
			bp[0] = s;
			bp[1] = s >> 8;
		}
		break;

	case AFMT_S16_BE:
		for (i = 0; i < cnt; i++, sp++, bp += 2) {
			s = *sp;
			bp[1] = s;
			bp[0] = s >> 8;
		}
		break;
	}
	
}

static void usbin_convert(struct usbin *u, unsigned char *buffer, unsigned int samples)