path: root/sound/usb/usx2y/usbusx2yaudio.c

/*
 *   US-X2Y AUDIO
 *   Copyright (c) 2002-2004 by Karsten Wiese
 *
 *   based on
 *
 *   (Tentative) USB Audio Driver for ALSA
 *
 *   Main and PCM part
 *
 *   Copyright (c) 2002 by Takashi Iwai <tiwai@suse.de>
 *
 *   Many codes borrowed from audio.c by 
 *	    Alan Cox (alan@lxorguk.ukuu.org.uk)
 *	    Thomas Sailer (sailer@ife.ee.ethz.ch)
 *
 *
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation; either version 2 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program; if not, write to the Free Software
 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
 */


#include <sound/driver.h>
#include <linux/interrupt.h>
#include <linux/usb.h>
#include <sound/core.h>
#include <sound/info.h>
#include <sound/pcm.h>
#include <sound/pcm_params.h>
#include "usx2y.h"
#include "usbusx2y.h"

#define USX2Y_NRPACKS 4			/* Default value used for nr of packs per urb.
					  1 to 4 have been tested ok on uhci.
					  To use 3 on ohci, you'd need a patch:
					  look for "0000425-linux-2.6.9-rc4-mm1_ohci-hcd.patch.gz" on
					  "https://bugtrack.alsa-project.org/alsa-bug/bug_view_page.php?bug_id=0000425"
					  .
					  1, 2 and 4 work out of the box on ohci, if I recall correctly.
					  Bigger is safer operation,
					  smaller gives lower latencies.
					*/
#define USX2Y_NRPACKS_VARIABLE y	/* If your system works ok with this module's parameter
					   nrpacks set to 1, you might as well comment 
					   this #define out, and thereby produce smaller, faster code.
					   You'd also set USX2Y_NRPACKS to 1 then.
					*/

#ifdef USX2Y_NRPACKS_VARIABLE
 static int nrpacks = USX2Y_NRPACKS; /* number of packets per urb */
 #define  nr_of_packs() nrpacks
 module_param(nrpacks, int, 0444);
 MODULE_PARM_DESC(nrpacks, "Number of packets per URB.");
#else
 #define nr_of_packs() USX2Y_NRPACKS
#endif


static int usX2Y_urb_capt_retire(snd_usX2Y_substream_t *subs)
{
	struct urb	*urb = subs->completed_urb;
	snd_pcm_runtime_t *runtime = subs->pcm_substream->runtime;
	unsigned char	*cp;
	int 		i, len, lens = 0, hwptr_done = subs->hwptr_done;
	usX2Ydev_t	*usX2Y = subs->usX2Y;

	for (i = 0; i < nr_of_packs(); i++) {
		cp = (unsigned char*)urb->transfer_buffer + urb->iso_frame_desc[i].offset;
		if (urb->iso_frame_desc[i].status) { /* active? hmm, skip this */
			snd_printk("activ frame status %i. Most propably some hardware problem.\n", urb->iso_frame_desc[i].status);
			return urb->iso_frame_desc[i].status;
		}
		len = urb->iso_frame_desc[i].actual_length / usX2Y->stride;
		if (! len) {
			snd_printd("0 == len ERROR!\n");
			continue;
		}

		/* copy a data chunk */
		if ((hwptr_done + len) > runtime->buffer_size) {
			int cnt = runtime->buffer_size - hwptr_done;
			int blen = cnt * usX2Y->stride;
			memcpy(runtime->dma_area + hwptr_done * usX2Y->stride, cp, blen);
			memcpy(runtime->dma_area, cp + blen, len * usX2Y->stride - blen);
		} else {
			memcpy(runtime->dma_area + hwptr_done * usX2Y->stride, cp, len * usX2Y->stride);
		}
		lens += len;
		if ((hwptr_done += len) >= runtime->buffer_size)
			hwptr_done -= runtime->buffer_size;
	}

	subs->hwptr_done = hwptr_done;
	subs->transfer_done += lens;
	/* update the pointer, call callback if necessary */
	if (subs->transfer_done >= runtime->period_size) {
		subs->transfer_done -= runtime->period_size;
		snd_pcm_period_elapsed(subs->pcm_substream);
	}
	return 0;
}
/*
 * prepare urb for playback data pipe
 *
 * we copy the data directly from the pcm buffer.
 * the current position to be copied is held in hwptr field.
 * since a urb can handle only a single linear buffer, if the total
 * transferred area overflows the buffer boundary, we cannot send
 * it directly from the buffer.  thus the data is once copied to
 * a temporary buffer and urb points to that.
 */
static int usX2Y_urb_play_prepare(snd_usX2Y_substream_t *subs,
				  struct urb *cap_urb,
				  struct urb *urb)
{
	int count, counts, pack;
	usX2Ydev_t* usX2Y = subs->usX2Y;
	snd_pcm_runtime_t *runtime = subs->pcm_substream->runtime;

	count = 0;
	for (pack = 0; pack <  nr_of_packs(); pack++) {
		/* calculate the size of a packet */
		counts = cap_urb->iso_frame_desc[pack].actual_length / usX2Y->stride;
		count += counts;
		if (counts < 43 || counts > 50) {
			snd_printk("should not be here with counts=%i\n", counts);
			return