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

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *   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)
 */


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

/* 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 4

/* 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.
 */
#define USX2Y_NRPACKS_VARIABLE 1

#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(struct snd_usx2y_substream *subs)
{
	struct urb	*urb = subs->completed_urb;
	struct snd_pcm_runtime *runtime = subs->pcm_substream->runtime;
	unsigned char	*cp;
	int		i, len, lens = 0, hwptr_done = subs->hwptr_done;
	int		cnt, blen;
	struct usx2ydev	*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(KERN_ERR
				   "active frame status %i. Most probably 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) {
			cnt = runtime->buffer_size - hwptr_done;
			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;
		hwptr_done += len;
		if (hwptr_done >= 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(struct snd_usx2y_substream *subs,
				  struct urb *cap_urb,
				  struct urb *urb)
{
	struct usx2ydev *usx2y = subs->usx2y;
	struct snd_pcm_runtime *runtime = subs->pcm_substream->runtime;
	int count, counts, pack, len;

	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(KERN_ERR "should not be here with counts=%i\n", counts);
			return -EPIPE;
		}
		/* set up descriptor */
		urb->iso_frame_desc[pack].offset = pack ?
			urb->iso_frame_desc[pack - 1].offset +
			urb->iso_frame_desc[pack - 1].length :
			0;
		urb->iso_frame_desc[pack].length = cap_urb->iso_frame_desc[pack].actual_length;
	}
	if (atomic_read(&subs->state) >= STATE_PRERUNNING) {
		if (subs->hwptr + count > runtime->buffer_size) {
			/* err, the transferred area goes over buffer boundary.
			 * copy the data to the temp buffer.
			 */
			len = runtime->buffer_size - subs->hwptr;
			urb->transfer_buffer = subs->tmpbuf;
			memcpy(subs->tmpbuf, runtime->dma_area +
			       subs->hwptr * usx2y->stride, len * usx2y->stride);
			memcpy(subs->tmpbuf + len * usx2y->stride,
			       runtime->dma_area, (count - len) * usx2y->stride);
			subs->hwptr += count;
			subs->hwptr -= runtime->buffer_size;
		} else {
			/* set the buffer pointer */
			urb->transfer_buffer = runtime->dma_area +