sound/firewire/oxfw/oxfw-stream.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * oxfw_stream.c - a part of driver for OXFW970/971 based devices
  *
  * Copyright (c) 2014 Takashi Sakamoto
  */

 #include "oxfw.h"
 #include <linux/delay.h>

 #define AVC_GENERIC_FRAME_MAXIMUM_BYTES	512
 #define READY_TIMEOUT_MS	600

 /*
  * According to datasheet of Oxford Semiconductor:
  *  OXFW970: 32.0/44.1/48.0/96.0 Khz, 8 audio channels I/O
  *  OXFW971: 32.0/44.1/48.0/88.2/96.0/192.0 kHz, 16 audio channels I/O, MIDI I/O
  */
 static const unsigned int oxfw_rate_table[] = {
 	[0] = 32000,
 	[1] = 44100,
 	[2] = 48000,
 	[3] = 88200,
 	[4] = 96000,
 	[5] = 192000,
 };

 /*
  * See Table 5.7 – Sampling frequency for Multi-bit Audio
  * in AV/C Stream Format Information Specification 1.1 (Apr 2005, 1394TA)
  */
 static const unsigned int avc_stream_rate_table[] = {
 	[0] = 0x02,
 	[1] = 0x03,
 	[2] = 0x04,
 	[3] = 0x0a,
 	[4] = 0x05,
 	[5] = 0x07,
 };

 static int set_rate(struct snd_oxfw *oxfw, unsigned int rate)
 {
 	int err;

 	err = avc_general_set_sig_fmt(oxfw->unit, rate,
 				      AVC_GENERAL_PLUG_DIR_IN, 0);
 	if (err < 0)
 		goto end;

 	if (oxfw->has_output)
 		err = avc_general_set_sig_fmt(oxfw->unit, rate,
 					      AVC_GENERAL_PLUG_DIR_OUT, 0);
 end:
 	return err;
 }

 static int set_stream_format(struct snd_oxfw *oxfw, struct amdtp_stream *s,
 			     unsigned int rate, unsigned int pcm_channels)
 {
 	u8 **formats;
 	struct snd_oxfw_stream_formation formation;
 	enum avc_general_plug_dir dir;
 	unsigned int len;
 	int i, err;

 	if (s == &oxfw->tx_stream) {
 		formats = oxfw->tx_stream_formats;
 		dir = AVC_GENERAL_PLUG_DIR_OUT;
 	} else {
 		formats = oxfw->rx_stream_formats;
 		dir = AVC_GENERAL_PLUG_DIR_IN;
 	}

 	/* Seek stream format for requirements. */
 	for (i = 0; i < SND_OXFW_STREAM_FORMAT_ENTRIES; i++) {
 		err = snd_oxfw_stream_parse_format(formats[i], &formation);
 		if (err < 0)
 			return err;

 		if ((formation.rate == rate) && (formation.pcm == pcm_channels))
 			break;
 	}
 	if (i == SND_OXFW_STREAM_FORMAT_ENTRIES)
 		return -EINVAL;

 	/* If assumed, just change rate. */
 	if (oxfw->assumed)
 		return set_rate(oxfw, rate);

 	/* Calculate format length. */
 	len = 5 + formats[i][4] * 2;

 	err = avc_stream_set_format(oxfw->unit, dir, 0, formats[i], len);
 	if (err < 0)
 		return err;

 	/* Some requests just after changing format causes freezing. */
 	msleep(100);

 	return 0;
 }

 static int start_stream(struct snd_oxfw *oxfw, struct amdtp_stream *stream)
 {
 	struct cmp_connection *conn;
 	int err;

 	if (stream == &oxfw->rx_stream)
 		conn = &oxfw->in_conn;
 	else
 		conn = &oxfw->out_conn;

 	err = cmp_connection_establish(conn);
 	if (err < 0)
 		return err;

 	err = amdtp_domain_add_stream(&oxfw->domain, stream,
 				      conn->resources.channel, conn->speed);
 	if (err < 0) {
 		cmp_connection_break(conn);
 		return err;
 	}

 	return 0;
 }

 static int check_connection_used_by_others(struct snd_oxfw *oxfw,
 					   struct amdtp_stream *stream)
 {
 	struct cmp_connection *conn;
 	bool used;
 	int err;

 	if (stream == &oxfw->tx_stream)
 		conn = &oxfw->out_conn;
 	else
 		conn = &oxfw->in_conn;

 	err = cmp_connection_check_used(conn, &used);
 	if ((err >= 0) && used && !amdtp_stream_running(stream)) {
 		dev_err(&oxfw->unit->device,
 			"Connection established by others: %cPCR[%d]\n",
 			(conn->direction == CMP_OUTPUT) ? 'o' : 'i',
 			conn->pcr_index);
 		err = -EBUSY;
 	}

 	return err;
 }

 static int init_stream(struct snd_oxfw *oxfw, struct amdtp_stream *stream)
 {
 	struct cmp_connection *conn;
 	enum cmp_direction c_dir;
 	enum amdtp_stream_direction s_dir;
 	unsigned int flags = 0;
 	int err;

 	if (!(oxfw->quirks & SND_OXFW_QUIRK_BLOCKING_TRANSMISSION))
 		flags |= CIP_NONBLOCKING;
 	else
 		flags |= CIP_BLOCKING;

 	// OXFW 970/971 has no function to generate playback timing according to the sequence
 	// of value in syt field, thus the packet should include NO_INFO value in the field.
 	// However, some models just ignore data blocks in packet with NO_INFO for audio data
 	// processing.
 	if (!(oxfw->quirks & SND_OXFW_QUIRK_IGNORE_NO_INFO_PACKET))
 		flags |= CIP_UNAWARE_SYT;

 	if (stream == &oxfw->tx_stream) {
 		conn = &oxfw->out_conn;
 		c_dir = CMP_OUTPUT;
 		s_dir = AMDTP_IN_STREAM;

 		if (oxfw->quirks & SND_OXFW_QUIRK_JUMBO_PAYLOAD)
 			flags |= CIP_JUMBO_PAYLOAD;
 		if (oxfw->quirks & SND_OXFW_QUIRK_WRONG_DBS)
 			flags |= CIP_WRONG_DBS;
 	} else {
 		conn = &oxfw->in_conn;
 		c_dir = CMP_INPUT;
 		s_dir = AMDTP_OUT_STREAM;
 	}

 	err = cmp_connection_init(conn, oxfw->unit, c_dir, 0);
 	if (err < 0)
 		return err;

 	err = amdtp_am824_init(stream, oxfw->unit, s_dir, flags);
 	if (err < 0) {
 		cmp_connection_destroy(conn);
 		return err;
 	}

 	return 0;
 }

 static int keep_resources(struct snd_oxfw *oxfw, struct amdtp_stream *stream)
 {
 	enum avc_general_plug_dir dir;
 	u8 **formats;
 	struct snd_oxfw_stream_formation formation;
 	struct cmp_connection *conn;
 	int i;
 	int err;

 	if (stream == &oxfw->rx_stream) {
 		dir = AVC_GENERAL_PLUG_DIR_IN;
 		formats = oxfw->rx_stream_formats;
 		conn = &oxfw->in_conn;
 	} else {
 		dir = AVC_GENERAL_PLUG_DIR_OUT;
 		formats = oxfw->tx_stream_formats;
 		conn = &oxfw->out_conn;
 	}

 	err = snd_oxfw_stream_get_current_formation(oxfw, dir, &formation);
 	if (err < 0)
 		return err;

 	for (i = 0; i < SND_OXFW_STREAM_FORMAT_ENTRIES; i++) {
 		struct snd_oxfw_stream_formation fmt;

 		if (formats[i] == NULL)
 			break;

 		err = snd_oxfw_stream_parse_format(formats[i], &fmt);
 		if (err < 0)
 			return err;

 		if (fmt.rate == formation.rate && fmt.pcm == formation.pcm &&
 		    fmt.midi == formation.midi)
 			break;
 	}
 	if (i == SND_OXFW_STREAM_FORMAT_ENTRIES)
 		return -EINVAL;

 	// The stream should have one pcm channels at least.
 	if (formation.pcm == 0)
 		return -EINVAL;

 	err = amdtp_am824_set_parameters(stream, formation.rate, formation.pcm,
 					 formation.midi * 8, false);
 	if (err < 0)
 		return err;

 	return cmp_connection_reserve(conn, amdtp_stream_get_max_payload(stream));
 }

 int snd_oxfw_stream_reserve_duplex(struct snd_oxfw *oxfw,
 				   struct amdtp_stream *stream,
 				   unsigned int rate, unsigned int pcm_channels,
 				   unsigned int frames_per_period,
 				   unsigned int frames_per_buffer)
 {
 	struct snd_oxfw_stream_formation formation;
 	enum avc_general_plug_dir dir;
 	int err;

 	// Considering JACK/FFADO streaming:
 	// TODO: This can be removed hwdep functionality becomes popular.
 	err = check_connection_used_by_others(oxfw, &oxfw->rx_stream);
 	if (err < 0)
 		return err;
 	if (oxfw->has_output) {
 		err = check_connection_used_by_others(oxfw, &oxfw->tx_stream);
 		if (err < 0)
 			return err;
 	}

 	if (stream == &oxfw->tx_stream)
 		dir = AVC_GENERAL_PLUG_DIR_OUT;
 	else
 		dir = AVC_GENERAL_PLUG_DIR_IN;

 	err = snd_oxfw_stream_get_current_formation(oxfw, dir, &formation);
 	if (err < 0)
 		return err;
 	if (rate == 0) {
 		rate = formation.rate;
 		pcm_channels = formation.pcm;
 	}
 	if (formation.rate != rate || formation.pcm != pcm_channels) {
 		amdtp_domain_stop(&oxfw->domain);

 		cmp_connection_break(&oxfw->in_conn);
 		cmp_connection_release(&oxfw->in_conn);

 		if (oxfw->has_output) {
 			cmp_connection_break(&oxfw->out_conn);
 			cmp_connection_release(&oxfw->out_conn);
 		}
 	}

 	if (oxfw->substreams_count == 0 ||
 	    formation.rate != rate || formation.pcm != pcm_channels) {
 		err = set_stream_format(oxfw, stream, rate, pcm_channels);
 		if (err < 0) {
 			dev_err(&oxfw->unit->device,
 				"fail to set stream format: %d\n", err);
 			return err;
 		}

 		err = keep_resources(oxfw, &oxfw->rx_stream);
 		if (err < 0)
 			return err;

 		if (oxfw->has_output) {
 			err = keep_resources(oxfw, &oxfw->tx_stream);
 			if (err < 0) {
 				cmp_connection_release(&oxfw->in_conn);
 				return err;
 			}
 		}

 		err = amdtp_domain_set_events_per_period(&oxfw->domain,
 					frames_per_period, frames_per_buffer);
 		if (err < 0) {
 			cmp_connection_release(&oxfw->in_conn);
 			if (oxfw->has_output)
 				cmp_connection_release(&oxfw->out_conn);
 			return err;
 		}
 	}

 	return 0;
 }

 int snd_oxfw_stream_start_duplex(struct snd_oxfw *oxfw)
 {
 	int err;

 	if (oxfw->substreams_count == 0)
 		return -EIO;

 	if (amdtp_streaming_error(&oxfw->rx_stream) ||
 	    amdtp_streaming_error(&oxfw->tx_stream)) {
 		amdtp_domain_stop(&oxfw->domain);

 		cmp_connection_break(&oxfw->in_conn);
 		if (oxfw->has_output)
 			cmp_connection_break(&oxfw->out_conn);
 	}

 	if (!amdtp_stream_running(&oxfw->rx_stream)) {
 		unsigned int tx_init_skip_cycles = 0;
 		bool replay_seq = false;

 		err = start_stream(oxfw, &oxfw->rx_stream);
 		if (err < 0) {
 			dev_err(&oxfw->unit->device,
 				"fail to prepare rx stream: %d\n", err);
 			goto error;
 		}

 		if (oxfw->has_output &&
 		    !amdtp_stream_running(&oxfw->tx_stream)) {
 			err = start_stream(oxfw, &oxfw->tx_stream);
 			if (err < 0) {
 				dev_err(&oxfw->unit->device,
 					"fail to prepare tx stream: %d\n", err);
 				goto error;
 			}

 			if (oxfw->quirks & SND_OXFW_QUIRK_JUMBO_PAYLOAD) {
 				// Just after changing sampling transfer frequency, many cycles are
 				// skipped for packet transmission.
 				tx_init_skip_cycles = 400;
 			} else if (oxfw->quirks & SND_OXFW_QUIRK_VOLUNTARY_RECOVERY) {
 				// It takes a bit time for target device to adjust event frequency
 				// according to nominal event frequency in isochronous packets from
 				// ALSA oxfw driver.
 				tx_init_skip_cycles = 4000;
 			} else {
 				replay_seq = true;
 			}
 		}

 		// NOTE: The device ignores presentation time expressed by the value of syt field
 		// of CIP header in received packets. The sequence of the number of data blocks per
 		// packet is important for media clock recovery.
 		err = amdtp_domain_start(&oxfw->domain, tx_init_skip_cycles, replay_seq, false);
 		if (err < 0)
 			goto error;

 		if (!amdtp_domain_wait_ready(&oxfw->domain, READY_TIMEOUT_MS)) {
 			err = -ETIMEDOUT;
 			goto error;
 		}
 	}

 	return 0;
 error:
 	amdtp_domain_stop(&oxfw->domain);

 	cmp_connection_break(&oxfw->in_conn);
 	if (oxfw->has_output)
 		cmp_connection_break(&oxfw->out_conn);

 	return err;
 }

 void snd_oxfw_stream_stop_duplex(struct snd_oxfw *oxfw)
 {
 	if (oxfw->substreams_count == 0) {
 		amdtp_domain_stop(&oxfw->domain);

 		cmp_connection_break(&oxfw->in_conn);
 		cmp_connection_release(&oxfw->in_conn);

 		if (oxfw->has_output) {
 			cmp_connection_break(&oxfw->out_conn);
 			cmp_connection_release(&oxfw->out_conn);
 		}
 	}
 }

 static void destroy_stream(struct snd_oxfw *oxfw, struct amdtp_stream *stream)
 {
 	struct cmp_connection *conn;

 	if (stream == &oxfw->tx_stream)
 		conn = &oxfw->out_conn;
 	else
 		conn = &oxfw->in_conn;

 	amdtp_stream_destroy(stream);
 	cmp_connection_destroy(conn);
 }

 int snd_oxfw_stream_init_duplex(struct snd_oxfw *oxfw)
 {
 	int err;

 	err = init_stream(oxfw, &oxfw->rx_stream);
 	if (err < 0)
 		return err;

 	if (oxfw->has_output) {
 		err = init_stream(oxfw, &oxfw->tx_stream);
 		if (err < 0) {
 			destroy_stream(oxfw, &oxfw->rx_stream);
 			return err;
 		}
 	}

 	err = amdtp_domain_init(&oxfw->domain);
 	if (err < 0) {
 		destroy_stream(oxfw, &oxfw->rx_stream);
 		if (oxfw->has_output)
 			destroy_stream(oxfw, &oxfw->tx_stream);
 	}

 	return err;
 }

 // This function should be called before starting the stream or after stopping
 // the streams.
 void snd_oxfw_stream_destroy_duplex(struct snd_oxfw *oxfw)
 {
 	amdtp_domain_destroy(&oxfw->domain);

 	destroy_stream(oxfw, &oxfw->rx_stream);

 	if (oxfw->has_output)
 		destroy_stream(oxfw, &oxfw->tx_stream);
 }

 void snd_oxfw_stream_update_duplex(struct snd_oxfw *oxfw)
 {
 	amdtp_domain_stop(&oxfw->domain);

 	cmp_connection_break(&oxfw->in_conn);

 	amdtp_stream_pcm_abort(&oxfw->rx_stream);

 	if (oxfw->has_output) {
 		cmp_connection_break(&oxfw->out_conn);

 		amdtp_stream_pcm_abort(&oxfw->tx_stream);
 	}
 }

 int snd_oxfw_stream_get_current_formation(struct snd_oxfw *oxfw,
 				enum avc_general_plug_dir dir,
 				struct snd_oxfw_stream_formation *formation)
 {
 	u8 *format;
 	unsigned int len;
 	int err;

 	len = AVC_GENERIC_FRAME_MAXIMUM_BYTES;
 	format = kmalloc(len, GFP_KERNEL);
 	if (format == NULL)
 		return -ENOMEM;

 	err = avc_stream_get_format_single(oxfw->unit, dir, 0, format, &len);
 	if (err < 0)
 		goto end;
 	if (len < 3) {
 		err = -EIO;
 		goto end;
 	}

 	err = snd_oxfw_stream_parse_format(format, formation);
 end:
 	kfree(format);
 	return err;
 }

 /*
  * See Table 6.16 - AM824 Stream Format
  *     Figure 6.19 - format_information field for AM824 Compound
  * in AV/C Stream Format Information Specification 1.1 (Apr 2005, 1394TA)
  * Also 'Clause 12 AM824 sequence adaption layers' in IEC 61883-6:2005
  */
 int snd_oxfw_stream_parse_format(u8 *format,
 				 struct snd_oxfw_stream_formation *formation)
 {
 	unsigned int i, e, channels, type;

 	memset(formation, 0, sizeof(struct snd_oxfw_stream_formation));

 	/*
 	 * this module can support a hierarchy combination that:
 	 *  Root:	Audio and Music (0x90)
 	 *  Level 1:	AM824 Compound  (0x40)
 	 */
 	if ((format[0] != 0x90) || (format[1] != 0x40))
 		return -ENXIO;

 	/* check the sampling rate */
 	for (i = 0; i < ARRAY_SIZE(avc_stream_rate_table); i++) {
 		if (format[2] == avc_stream_rate_table[i])
 			break;
 	}
 	if (i == ARRAY_SIZE(avc_stream_rate_table))
 		return -ENXIO;

 	formation->rate = oxfw_rate_table[i];

 	for (e = 0; e < format[4]; e++) {
 		channels = format[5 + e * 2];
 		type = format[6 + e * 2];

 		switch (type) {
 		/* IEC 60958 Conformant, currently handled as MBLA */
 		case 0x00:
 		/* Multi Bit Linear Audio (Raw) */
 		case 0x06:
 			formation->pcm += channels;
 			break;
 		/* MIDI Conformant */
 		case 0x0d:
 			formation->midi = channels;
 			break;
 		/* IEC 61937-3 to 7 */
 		case 0x01:
 		case 0x02:
 		case 0x03:
 		case 0x04:
 		case 0x05:
 		/* Multi Bit Linear Audio */
 		case 0x07:	/* DVD-Audio */
 		case 0x0c:	/* High Precision */
 		/* One Bit Audio */
 		case 0x08:	/* (Plain) Raw */
 		case 0x09:	/* (Plain) SACD */
 		case 0x0a:	/* (Encoded) Raw */
 		case 0x0b:	/* (Encoded) SACD */
 		/* SMPTE Time-Code conformant */
 		case 0x0e:
 		/* Sample Count */
 		case 0x0f:
 		/* Anciliary Data */
 		case 0x10:
 		/* Synchronization Stream (Stereo Raw audio) */
 		case 0x40:
 		/* Don't care */
 		case 0xff:
 		default:
 			return -ENXIO;	/* not supported */
 		}
 	}

 	if (formation->pcm  > AM824_MAX_CHANNELS_FOR_PCM ||
 	    formation->midi > AM824_MAX_CHANNELS_FOR_MIDI)
 		return -ENXIO;

 	return 0;
 }

 static int
 assume_stream_formats(struct snd_oxfw *oxfw, enum avc_general_plug_dir dir,
 		      unsigned int pid, u8 *buf, unsigned int *len,
 		      u8 **formats)
 {
 	struct snd_oxfw_stream_formation formation;
 	unsigned int i, eid;
 	int err;

 	/* get format at current sampling rate */
 	err = avc_stream_get_format_single(oxfw->unit, dir, pid, buf, len);
 	if (err < 0) {
 		dev_err(&oxfw->unit->device,
 		"fail to get current stream format for isoc %s plug %d:%d\n",
 			(dir == AVC_GENERAL_PLUG_DIR_IN) ? "in" : "out",
 			pid, err);
 		goto end;
 	}

 	/* parse and set stream format */
 	eid = 0;
 	err = snd_oxfw_stream_parse_format(buf, &formation);
 	if (err < 0)
 		goto end;

 	formats[eid] = devm_kmemdup(&oxfw->card->card_dev, buf, *len,
 				    GFP_KERNEL);
 	if (!formats[eid]) {
 		err = -ENOMEM;
 		goto end;
 	}

 	/* apply the format for each available sampling rate */
 	for (i = 0; i < ARRAY_SIZE(oxfw_rate_table); i++) {
 		if (formation.rate == oxfw_rate_table[i])
 			continue;

 		err = avc_general_inquiry_sig_fmt(oxfw->unit,
 						  oxfw_rate_table[i],
 						  dir, pid);
 		if (err < 0)
 			continue;

 		eid++;
 		formats[eid] = devm_kmemdup(&oxfw->card->card_dev, buf, *len,
 					    GFP_KERNEL);
 		if (formats[eid] == NULL) {
 			err = -ENOMEM;
 			goto end;
 		}
 		formats[eid][2] = avc_stream_rate_table[i];
 	}

 	err = 0;
 	oxfw->assumed = true;
 end:
 	return err;
 }

 static int fill_stream_formats(struct snd_oxfw *oxfw,
 			       enum avc_general_plug_dir dir,
 			       unsigned short pid)
 {
 	u8 *buf, **formats;
 	unsigned int len, eid = 0;
 	struct snd_oxfw_stream_formation dummy;
 	int err;

 	buf = kmalloc(AVC_GENERIC_FRAME_MAXIMUM_BYTES, GFP_KERNEL);
 	if (buf == NULL)
 		return -ENOMEM;

 	if (dir == AVC_GENERAL_PLUG_DIR_OUT)
 		formats = oxfw->tx_stream_formats;
 	else
 		formats = oxfw->rx_stream_formats;

 	/* get first entry */
 	len = AVC_GENERIC_FRAME_MAXIMUM_BYTES;
 	err = avc_stream_get_format_list(oxfw->unit, dir, 0, buf, &len, 0);
 	if (err == -ENXIO) {
 		/* LIST subfunction is not implemented */
 		len = AVC_GENERIC_FRAME_MAXIMUM_BYTES;
 		err = assume_stream_formats(oxfw, dir, pid, buf, &len,
 					    formats);
 		goto end;
 	} else if (err < 0) {
 		dev_err(&oxfw->unit->device,
 			"fail to get stream format %d for isoc %s plug %d:%d\n",
 			eid, (dir == AVC_GENERAL_PLUG_DIR_IN) ? "in" : "out",
 			pid, err);
 		goto end;
 	}

 	/* LIST subfunction is implemented */
 	while (eid < SND_OXFW_STREAM_FORMAT_ENTRIES) {
 		/* The format is too short. */
 		if (len < 3) {
 			err = -EIO;
 			break;
 		}

 		/* parse and set stream format */
 		err = snd_oxfw_stream_parse_format(buf, &dummy);
 		if (err < 0)
 			break;

 		formats[eid] = devm_kmemdup(&oxfw->card->card_dev, buf, len,
 					    GFP_KERNEL);
 		if (!formats[eid]) {
 			err = -ENOMEM;
 			break;
 		}

 		/* get next entry */
 		len = AVC_GENERIC_FRAME_MAXIMUM_BYTES;
 		err = avc_stream_get_format_list(oxfw->unit, dir, 0,
 						 buf, &len, ++eid);
 		/* No entries remained. */
 		if (err == -EINVAL) {
 			err = 0;
 			break;
 		} else if (err < 0) {
 			dev_err(&oxfw->unit->device,
 			"fail to get stream format %d for isoc %s plug %d:%d\n",
 				eid, (dir == AVC_GENERAL_PLUG_DIR_IN) ? "in" :
 									"out",
 				pid, err);
 			break;
 		}
 	}
 end:
 	kfree(buf);
 	return err;
 }

 int snd_oxfw_stream_discover(struct snd_oxfw *oxfw)
 {
 	u8 plugs[AVC_PLUG_INFO_BUF_BYTES];
 	struct snd_oxfw_stream_formation formation;
 	u8 *format;
 	unsigned int i;
 	int err;

 	/* the number of plugs for isoc in/out, ext in/out  */
 	err = avc_general_get_plug_info(oxfw->unit, 0x1f, 0x07, 0x00, plugs);
 	if (err < 0) {
 		dev_err(&oxfw->unit->device,
 		"fail to get info for isoc/external in/out plugs: %d\n",
 			err);
 		goto end;
 	} else if ((plugs[0] == 0) && (plugs[1] == 0)) {
 		err = -ENXIO;
 		goto end;
 	}

 	/* use oPCR[0] if exists */
 	if (plugs[1] > 0) {
 		err = fill_stream_formats(oxfw, AVC_GENERAL_PLUG_DIR_OUT, 0);
 		if (err < 0) {
 			if (err != -ENXIO)
 				return err;

 			// The oPCR is not available for isoc communication.
 			err = 0;
 		} else {
 			for (i = 0; i < SND_OXFW_STREAM_FORMAT_ENTRIES; i++) {
 				format = oxfw->tx_stream_formats[i];
 				if (format == NULL)
 					continue;
 				err = snd_oxfw_stream_parse_format(format,
 								   &formation);
 				if (err < 0)
 					continue;

 				/* Add one MIDI port. */
 				if (formation.midi > 0)
 					oxfw->midi_input_ports = 1;
 			}

 			oxfw->has_output = true;
 		}
 	}

 	/* use iPCR[0] if exists */
 	if (plugs[0] > 0) {
 		err = fill_stream_formats(oxfw, AVC_GENERAL_PLUG_DIR_IN, 0);
 		if (err < 0) {
 			if (err != -ENXIO)
 				return err;

 			// The iPCR is not available for isoc communication.
 			err = 0;
 		} else {
 			for (i = 0; i < SND_OXFW_STREAM_FORMAT_ENTRIES; i++) {
 				format = oxfw->rx_stream_formats[i];
 				if (format == NULL)
 					continue;
 				err = snd_oxfw_stream_parse_format(format,
 								   &formation);
 				if (err < 0)
 					continue;

 				/* Add one MIDI port. */
 				if (formation.midi > 0)
 					oxfw->midi_output_ports = 1;
 			}

 			oxfw->has_input = true;
 		}
 	}
 end:
 	return err;
 }

 void snd_oxfw_stream_lock_changed(struct snd_oxfw *oxfw)
 {
 	oxfw->dev_lock_changed = true;
 	wake_up(&oxfw->hwdep_wait);
 }

 int snd_oxfw_stream_lock_try(struct snd_oxfw *oxfw)
 {
 	int err;

 	spin_lock_irq(&oxfw->lock);

 	/* user land lock this */
 	if (oxfw->dev_lock_count < 0) {
 		err = -EBUSY;
 		goto end;
 	}

 	/* this is the first time */
 	if (oxfw->dev_lock_count++ == 0)
 		snd_oxfw_stream_lock_changed(oxfw);
 	err = 0;
 end:
 	spin_unlock_irq(&oxfw->lock);
 	return err;
 }

 void snd_oxfw_stream_lock_release(struct snd_oxfw *oxfw)
 {
 	spin_lock_irq(&oxfw->lock);

 	if (WARN_ON(oxfw->dev_lock_count <= 0))
 		goto end;
 	if (--oxfw->dev_lock_count == 0)
 		snd_oxfw_stream_lock_changed(oxfw);
 end:
 	spin_unlock_irq(&oxfw->lock);
 }
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* oxfw_stream.c - a part of driver for OXFW970/971 based devices
	*
	* Copyright (c) 2014 Takashi Sakamoto
	*/

	#include "oxfw.h"
	#include <linux/delay.h>

	#define AVC_GENERIC_FRAME_MAXIMUM_BYTES 512
	#define READY_TIMEOUT_MS 600

	/*
	* According to datasheet of Oxford Semiconductor:
	* OXFW970: 32.0/44.1/48.0/96.0 Khz, 8 audio channels I/O
	* OXFW971: 32.0/44.1/48.0/88.2/96.0/192.0 kHz, 16 audio channels I/O, MIDI I/O
	*/
	static const unsigned int oxfw_rate_table[] = {
	[0] = 32000,
	[1] = 44100,
	[2] = 48000,
	[3] = 88200,
	[4] = 96000,
	[5] = 192000,
	};

	/*
	* See Table 5.7 – Sampling frequency for Multi-bit Audio
	* in AV/C Stream Format Information Specification 1.1 (Apr 2005, 1394TA)
	*/
	static const unsigned int avc_stream_rate_table[] = {
	[0] = 0x02,
	[1] = 0x03,
	[2] = 0x04,
	[3] = 0x0a,
	[4] = 0x05,
	[5] = 0x07,
	};

	static int set_rate(struct snd_oxfw *oxfw, unsigned int rate)
	{
	int err;

	err = avc_general_set_sig_fmt(oxfw->unit, rate,
	AVC_GENERAL_PLUG_DIR_IN, 0);
	if (err < 0)
	goto end;

	if (oxfw->has_output)
	err = avc_general_set_sig_fmt(oxfw->unit, rate,
	AVC_GENERAL_PLUG_DIR_OUT, 0);
	end:
	return err;
	}

	static int set_stream_format(struct snd_oxfw oxfw, struct amdtp_stream s,
	unsigned int rate, unsigned int pcm_channels)
	{
	u8 **formats;
	struct snd_oxfw_stream_formation formation;
	enum avc_general_plug_dir dir;
	unsigned int len;
	int i, err;

	if (s == &oxfw->tx_stream) {
	formats = oxfw->tx_stream_formats;
	dir = AVC_GENERAL_PLUG_DIR_OUT;
	} else {
	formats = oxfw->rx_stream_formats;
	dir = AVC_GENERAL_PLUG_DIR_IN;
	}

	/* Seek stream format for requirements. */
	for (i = 0; i < SND_OXFW_STREAM_FORMAT_ENTRIES; i++) {
	err = snd_oxfw_stream_parse_format(formats[i], &formation);
	if (err < 0)
	return err;

	if ((formation.rate == rate) && (formation.pcm == pcm_channels))
	break;
	}
	if (i == SND_OXFW_STREAM_FORMAT_ENTRIES)
	return -EINVAL;

	/* If assumed, just change rate. */
	if (oxfw->assumed)
	return set_rate(oxfw, rate);

	/* Calculate format length. */
	len = 5 + formats[i][4] * 2;

	err = avc_stream_set_format(oxfw->unit, dir, 0, formats[i], len);
	if (err < 0)
	return err;

	/* Some requests just after changing format causes freezing. */
	msleep(100);

	return 0;
	}

	static int start_stream(struct snd_oxfw oxfw, struct amdtp_stream stream)
	{
	struct cmp_connection *conn;
	int err;

	if (stream == &oxfw->rx_stream)
	conn = &oxfw->in_conn;
	else
	conn = &oxfw->out_conn;

	err = cmp_connection_establish(conn);
	if (err < 0)
	return err;

	err = amdtp_domain_add_stream(&oxfw->domain, stream,
	conn->resources.channel, conn->speed);
	if (err < 0) {
	cmp_connection_break(conn);
	return err;
	}

	return 0;
	}

	static int check_connection_used_by_others(struct snd_oxfw *oxfw,
	struct amdtp_stream *stream)
	{
	struct cmp_connection *conn;
	bool used;
	int err;

	if (stream == &oxfw->tx_stream)
	conn = &oxfw->out_conn;
	else
	conn = &oxfw->in_conn;

	err = cmp_connection_check_used(conn, &used);
	if ((err >= 0) && used && !amdtp_stream_running(stream)) {
	dev_err(&oxfw->unit->device,
	"Connection established by others: %cPCR[%d]\n",
	(conn->direction == CMP_OUTPUT) ? 'o' : 'i',
	conn->pcr_index);
	err = -EBUSY;
	}

	return err;
	}

	static int init_stream(struct snd_oxfw oxfw, struct amdtp_stream stream)
	{
	struct cmp_connection *conn;
	enum cmp_direction c_dir;
	enum amdtp_stream_direction s_dir;
	unsigned int flags = 0;
	int err;

	if (!(oxfw->quirks & SND_OXFW_QUIRK_BLOCKING_TRANSMISSION))
	flags \|= CIP_NONBLOCKING;
	else
	flags \|= CIP_BLOCKING;

	// OXFW 970/971 has no function to generate playback timing according to the sequence
	// of value in syt field, thus the packet should include NO_INFO value in the field.
	// However, some models just ignore data blocks in packet with NO_INFO for audio data
	// processing.
	if (!(oxfw->quirks & SND_OXFW_QUIRK_IGNORE_NO_INFO_PACKET))
	flags \|= CIP_UNAWARE_SYT;

	if (stream == &oxfw->tx_stream) {
	conn = &oxfw->out_conn;
	c_dir = CMP_OUTPUT;
	s_dir = AMDTP_IN_STREAM;

	if (oxfw->quirks & SND_OXFW_QUIRK_JUMBO_PAYLOAD)
	flags \|= CIP_JUMBO_PAYLOAD;
	if (oxfw->quirks & SND_OXFW_QUIRK_WRONG_DBS)
	flags \|= CIP_WRONG_DBS;
	} else {
	conn = &oxfw->in_conn;
	c_dir = CMP_INPUT;
	s_dir = AMDTP_OUT_STREAM;
	}

	err = cmp_connection_init(conn, oxfw->unit, c_dir, 0);
	if (err < 0)
	return err;

	err = amdtp_am824_init(stream, oxfw->unit, s_dir, flags);
	if (err < 0) {
	cmp_connection_destroy(conn);
	return err;
	}

	return 0;
	}

	static int keep_resources(struct snd_oxfw oxfw, struct amdtp_stream stream)
	{
	enum avc_general_plug_dir dir;
	u8 **formats;
	struct snd_oxfw_stream_formation formation;
	struct cmp_connection *conn;
	int i;
	int err;

	if (stream == &oxfw->rx_stream) {
	dir = AVC_GENERAL_PLUG_DIR_IN;
	formats = oxfw->rx_stream_formats;
	conn = &oxfw->in_conn;
	} else {
	dir = AVC_GENERAL_PLUG_DIR_OUT;
	formats = oxfw->tx_stream_formats;
	conn = &oxfw->out_conn;
	}

	err = snd_oxfw_stream_get_current_formation(oxfw, dir, &formation);
	if (err < 0)
	return err;

	for (i = 0; i < SND_OXFW_STREAM_FORMAT_ENTRIES; i++) {
	struct snd_oxfw_stream_formation fmt;

	if (formats[i] == NULL)
	break;

	err = snd_oxfw_stream_parse_format(formats[i], &fmt);
	if (err < 0)
	return err;

	if (fmt.rate == formation.rate && fmt.pcm == formation.pcm &&
	fmt.midi == formation.midi)
	break;
	}
	if (i == SND_OXFW_STREAM_FORMAT_ENTRIES)
	return -EINVAL;

	// The stream should have one pcm channels at least.
	if (formation.pcm == 0)
	return -EINVAL;

	err = amdtp_am824_set_parameters(stream, formation.rate, formation.pcm,
	formation.midi * 8, false);
	if (err < 0)
	return err;

	return cmp_connection_reserve(conn, amdtp_stream_get_max_payload(stream));
	}

	int snd_oxfw_stream_reserve_duplex(struct snd_oxfw *oxfw,
	struct amdtp_stream *stream,
	unsigned int rate, unsigned int pcm_channels,
	unsigned int frames_per_period,
	unsigned int frames_per_buffer)
	{
	struct snd_oxfw_stream_formation formation;
	enum avc_general_plug_dir dir;
	int err;

	// Considering JACK/FFADO streaming:
	// TODO: This can be removed hwdep functionality becomes popular.
	err = check_connection_used_by_others(oxfw, &oxfw->rx_stream);
	if (err < 0)
	return err;
	if (oxfw->has_output) {
	err = check_connection_used_by_others(oxfw, &oxfw->tx_stream);
	if (err < 0)
	return err;
	}

	if (stream == &oxfw->tx_stream)
	dir = AVC_GENERAL_PLUG_DIR_OUT;
	else
	dir = AVC_GENERAL_PLUG_DIR_IN;

	err = snd_oxfw_stream_get_current_formation(oxfw, dir, &formation);
	if (err < 0)
	return err;
	if (rate == 0) {
	rate = formation.rate;
	pcm_channels = formation.pcm;
	}
	if (formation.rate != rate \|\| formation.pcm != pcm_channels) {
	amdtp_domain_stop(&oxfw->domain);

	cmp_connection_break(&oxfw->in_conn);
	cmp_connection_release(&oxfw->in_conn);

	if (oxfw->has_output) {
	cmp_connection_break(&oxfw->out_conn);
	cmp_connection_release(&oxfw->out_conn);
	}
	}

	if (oxfw->substreams_count == 0 \|\|
	formation.rate != rate \|\| formation.pcm != pcm_channels) {
	err = set_stream_format(oxfw, stream, rate, pcm_channels);
	if (err < 0) {
	dev_err(&oxfw->unit->device,
	"fail to set stream format: %d\n", err);
	return err;
	}

	err = keep_resources(oxfw, &oxfw->rx_stream);
	if (err < 0)
	return err;

	if (oxfw->has_output) {
	err = keep_resources(oxfw, &oxfw->tx_stream);
	if (err < 0) {
	cmp_connection_release(&oxfw->in_conn);
	return err;
	}
	}

	err = amdtp_domain_set_events_per_period(&oxfw->domain,
	frames_per_period, frames_per_buffer);
	if (err < 0) {
	cmp_connection_release(&oxfw->in_conn);
	if (oxfw->has_output)
	cmp_connection_release(&oxfw->out_conn);
	return err;
	}
	}

	return 0;
	}

	int snd_oxfw_stream_start_duplex(struct snd_oxfw *oxfw)
	{
	int err;

	if (oxfw->substreams_count == 0)
	return -EIO;

	if (amdtp_streaming_error(&oxfw->rx_stream) \|\|
	amdtp_streaming_error(&oxfw->tx_stream)) {
	amdtp_domain_stop(&oxfw->domain);

	cmp_connection_break(&oxfw->in_conn);
	if (oxfw->has_output)
	cmp_connection_break(&oxfw->out_conn);
	}

	if (!amdtp_stream_running(&oxfw->rx_stream)) {
	unsigned int tx_init_skip_cycles = 0;
	bool replay_seq = false;

	err = start_stream(oxfw, &oxfw->rx_stream);
	if (err < 0) {
	dev_err(&oxfw->unit->device,
	"fail to prepare rx stream: %d\n", err);
	goto error;
	}

	if (oxfw->has_output &&
	!amdtp_stream_running(&oxfw->tx_stream)) {
	err = start_stream(oxfw, &oxfw->tx_stream);
	if (err < 0) {
	dev_err(&oxfw->unit->device,
	"fail to prepare tx stream: %d\n", err);
	goto error;
	}

	if (oxfw->quirks & SND_OXFW_QUIRK_JUMBO_PAYLOAD) {
	// Just after changing sampling transfer frequency, many cycles are
	// skipped for packet transmission.
	tx_init_skip_cycles = 400;
	} else if (oxfw->quirks & SND_OXFW_QUIRK_VOLUNTARY_RECOVERY) {
	// It takes a bit time for target device to adjust event frequency
	// according to nominal event frequency in isochronous packets from
	// ALSA oxfw driver.
	tx_init_skip_cycles = 4000;
	} else {
	replay_seq = true;
	}
	}

	// NOTE: The device ignores presentation time expressed by the value of syt field
	// of CIP header in received packets. The sequence of the number of data blocks per
	// packet is important for media clock recovery.
	err = amdtp_domain_start(&oxfw->domain, tx_init_skip_cycles, replay_seq, false);
	if (err < 0)
	goto error;

	if (!amdtp_domain_wait_ready(&oxfw->domain, READY_TIMEOUT_MS)) {
	err = -ETIMEDOUT;
	goto error;
	}
	}

	return 0;
	error:
	amdtp_domain_stop(&oxfw->domain);

	cmp_connection_break(&oxfw->in_conn);
	if (oxfw->has_output)
	cmp_connection_break(&oxfw->out_conn);

	return err;
	}

	void snd_oxfw_stream_stop_duplex(struct snd_oxfw *oxfw)
	{
	if (oxfw->substreams_count == 0) {
	amdtp_domain_stop(&oxfw->domain);

	cmp_connection_break(&oxfw->in_conn);
	cmp_connection_release(&oxfw->in_conn);

	if (oxfw->has_output) {
	cmp_connection_break(&oxfw->out_conn);
	cmp_connection_release(&oxfw->out_conn);
	}
	}
	}

	static void destroy_stream(struct snd_oxfw oxfw, struct amdtp_stream stream)
	{
	struct cmp_connection *conn;

	if (stream == &oxfw->tx_stream)
	conn = &oxfw->out_conn;
	else
	conn = &oxfw->in_conn;

	amdtp_stream_destroy(stream);
	cmp_connection_destroy(conn);
	}

	int snd_oxfw_stream_init_duplex(struct snd_oxfw *oxfw)
	{
	int err;

	err = init_stream(oxfw, &oxfw->rx_stream);
	if (err < 0)
	return err;

	if (oxfw->has_output) {
	err = init_stream(oxfw, &oxfw->tx_stream);
	if (err < 0) {
	destroy_stream(oxfw, &oxfw->rx_stream);
	return err;
	}
	}

	err = amdtp_domain_init(&oxfw->domain);
	if (err < 0) {
	destroy_stream(oxfw, &oxfw->rx_stream);
	if (oxfw->has_output)
	destroy_stream(oxfw, &oxfw->tx_stream);
	}

	return err;
	}

	// This function should be called before starting the stream or after stopping
	// the streams.
	void snd_oxfw_stream_destroy_duplex(struct snd_oxfw *oxfw)
	{
	amdtp_domain_destroy(&oxfw->domain);

	destroy_stream(oxfw, &oxfw->rx_stream);

	if (oxfw->has_output)
	destroy_stream(oxfw, &oxfw->tx_stream);
	}

	void snd_oxfw_stream_update_duplex(struct snd_oxfw *oxfw)
	{
	amdtp_domain_stop(&oxfw->domain);

	cmp_connection_break(&oxfw->in_conn);

	amdtp_stream_pcm_abort(&oxfw->rx_stream);

	if (oxfw->has_output) {
	cmp_connection_break(&oxfw->out_conn);

	amdtp_stream_pcm_abort(&oxfw->tx_stream);
	}
	}

	int snd_oxfw_stream_get_current_formation(struct snd_oxfw *oxfw,
	enum avc_general_plug_dir dir,
	struct snd_oxfw_stream_formation *formation)
	{
	u8 *format;
	unsigned int len;
	int err;

	len = AVC_GENERIC_FRAME_MAXIMUM_BYTES;
	format = kmalloc(len, GFP_KERNEL);
	if (format == NULL)
	return -ENOMEM;

	err = avc_stream_get_format_single(oxfw->unit, dir, 0, format, &len);
	if (err < 0)
	goto end;
	if (len < 3) {
	err = -EIO;
	goto end;
	}

	err = snd_oxfw_stream_parse_format(format, formation);
	end:
	kfree(format);
	return err;
	}

	/*
	* See Table 6.16 - AM824 Stream Format
	* Figure 6.19 - format_information field for AM824 Compound
	* in AV/C Stream Format Information Specification 1.1 (Apr 2005, 1394TA)
	* Also 'Clause 12 AM824 sequence adaption layers' in IEC 61883-6:2005
	*/
	int snd_oxfw_stream_parse_format(u8 *format,
	struct snd_oxfw_stream_formation *formation)
	{
	unsigned int i, e, channels, type;

	memset(formation, 0, sizeof(struct snd_oxfw_stream_formation));

	/*
	* this module can support a hierarchy combination that:
	* Root: Audio and Music (0x90)
	* Level 1: AM824 Compound (0x40)
	*/
	if ((format[0] != 0x90) \|\| (format[1] != 0x40))
	return -ENXIO;

	/* check the sampling rate */
	for (i = 0; i < ARRAY_SIZE(avc_stream_rate_table); i++) {
	if (format[2] == avc_stream_rate_table[i])
	break;
	}
	if (i == ARRAY_SIZE(avc_stream_rate_table))
	return -ENXIO;

	formation->rate = oxfw_rate_table[i];

	for (e = 0; e < format[4]; e++) {
	channels = format[5 + e * 2];
	type = format[6 + e * 2];

	switch (type) {
	/* IEC 60958 Conformant, currently handled as MBLA */
	case 0x00:
	/* Multi Bit Linear Audio (Raw) */
	case 0x06:
	formation->pcm += channels;
	break;
	/* MIDI Conformant */
	case 0x0d:
	formation->midi = channels;
	break;
	/* IEC 61937-3 to 7 */
	case 0x01:
	case 0x02:
	case 0x03:
	case 0x04:
	case 0x05:
	/* Multi Bit Linear Audio */
	case 0x07: /* DVD-Audio */
	case 0x0c: /* High Precision */
	/* One Bit Audio */
	case 0x08: /* (Plain) Raw */
	case 0x09: /* (Plain) SACD */
	case 0x0a: /* (Encoded) Raw */
	case 0x0b: /* (Encoded) SACD */
	/* SMPTE Time-Code conformant */
	case 0x0e:
	/* Sample Count */
	case 0x0f:
	/* Anciliary Data */
	case 0x10:
	/* Synchronization Stream (Stereo Raw audio) */
	case 0x40:
	/* Don't care */
	case 0xff:
	default:
	return -ENXIO; /* not supported */
	}
	}

	if (formation->pcm > AM824_MAX_CHANNELS_FOR_PCM \|\|
	formation->midi > AM824_MAX_CHANNELS_FOR_MIDI)
	return -ENXIO;

	return 0;
	}

	static int
	assume_stream_formats(struct snd_oxfw *oxfw, enum avc_general_plug_dir dir,
	unsigned int pid, u8 buf, unsigned int len,
	u8 **formats)
	{
	struct snd_oxfw_stream_formation formation;
	unsigned int i, eid;
	int err;

	/* get format at current sampling rate */
	err = avc_stream_get_format_single(oxfw->unit, dir, pid, buf, len);
	if (err < 0) {
	dev_err(&oxfw->unit->device,
	"fail to get current stream format for isoc %s plug %d:%d\n",
	(dir == AVC_GENERAL_PLUG_DIR_IN) ? "in" : "out",
	pid, err);
	goto end;
	}

	/* parse and set stream format */
	eid = 0;
	err = snd_oxfw_stream_parse_format(buf, &formation);
	if (err < 0)
	goto end;

	formats[eid] = devm_kmemdup(&oxfw->card->card_dev, buf, *len,
	GFP_KERNEL);
	if (!formats[eid]) {
	err = -ENOMEM;
	goto end;
	}

	/* apply the format for each available sampling rate */
	for (i = 0; i < ARRAY_SIZE(oxfw_rate_table); i++) {
	if (formation.rate == oxfw_rate_table[i])
	continue;

	err = avc_general_inquiry_sig_fmt(oxfw->unit,
	oxfw_rate_table[i],
	dir, pid);
	if (err < 0)
	continue;

	eid++;
	formats[eid] = devm_kmemdup(&oxfw->card->card_dev, buf, *len,
	GFP_KERNEL);
	if (formats[eid] == NULL) {
	err = -ENOMEM;
	goto end;
	}
	formats[eid][2] = avc_stream_rate_table[i];
	}

	err = 0;
	oxfw->assumed = true;
	end:
	return err;
	}

	static int fill_stream_formats(struct snd_oxfw *oxfw,
	enum avc_general_plug_dir dir,
	unsigned short pid)
	{
	u8 buf, *formats;
	unsigned int len, eid = 0;
	struct snd_oxfw_stream_formation dummy;
	int err;

	buf = kmalloc(AVC_GENERIC_FRAME_MAXIMUM_BYTES, GFP_KERNEL);
	if (buf == NULL)
	return -ENOMEM;

	if (dir == AVC_GENERAL_PLUG_DIR_OUT)
	formats = oxfw->tx_stream_formats;
	else
	formats = oxfw->rx_stream_formats;

	/* get first entry */
	len = AVC_GENERIC_FRAME_MAXIMUM_BYTES;
	err = avc_stream_get_format_list(oxfw->unit, dir, 0, buf, &len, 0);
	if (err == -ENXIO) {
	/* LIST subfunction is not implemented */
	len = AVC_GENERIC_FRAME_MAXIMUM_BYTES;
	err = assume_stream_formats(oxfw, dir, pid, buf, &len,
	formats);
	goto end;
	} else if (err < 0) {
	dev_err(&oxfw->unit->device,
	"fail to get stream format %d for isoc %s plug %d:%d\n",
	eid, (dir == AVC_GENERAL_PLUG_DIR_IN) ? "in" : "out",
	pid, err);
	goto end;
	}

	/* LIST subfunction is implemented */
	while (eid < SND_OXFW_STREAM_FORMAT_ENTRIES) {
	/* The format is too short. */
	if (len < 3) {
	err = -EIO;
	break;
	}

	/* parse and set stream format */
	err = snd_oxfw_stream_parse_format(buf, &dummy);
	if (err < 0)
	break;

	formats[eid] = devm_kmemdup(&oxfw->card->card_dev, buf, len,
	GFP_KERNEL);
	if (!formats[eid]) {
	err = -ENOMEM;
	break;
	}

	/* get next entry */
	len = AVC_GENERIC_FRAME_MAXIMUM_BYTES;
	err = avc_stream_get_format_list(oxfw->unit, dir, 0,
	buf, &len, ++eid);
	/* No entries remained. */
	if (err == -EINVAL) {
	err = 0;
	break;
	} else if (err < 0) {
	dev_err(&oxfw->unit->device,
	"fail to get stream format %d for isoc %s plug %d:%d\n",
	eid, (dir == AVC_GENERAL_PLUG_DIR_IN) ? "in" :
	"out",
	pid, err);
	break;
	}
	}
	end:
	kfree(buf);
	return err;
	}

	int snd_oxfw_stream_discover(struct snd_oxfw *oxfw)
	{
	u8 plugs[AVC_PLUG_INFO_BUF_BYTES];
	struct snd_oxfw_stream_formation formation;
	u8 *format;
	unsigned int i;
	int err;

	/* the number of plugs for isoc in/out, ext in/out */
	err = avc_general_get_plug_info(oxfw->unit, 0x1f, 0x07, 0x00, plugs);
	if (err < 0) {
	dev_err(&oxfw->unit->device,
	"fail to get info for isoc/external in/out plugs: %d\n",
	err);
	goto end;
	} else if ((plugs[0] == 0) && (plugs[1] == 0)) {
	err = -ENXIO;
	goto end;
	}

	/* use oPCR[0] if exists */
	if (plugs[1] > 0) {
	err = fill_stream_formats(oxfw, AVC_GENERAL_PLUG_DIR_OUT, 0);
	if (err < 0) {
	if (err != -ENXIO)
	return err;

	// The oPCR is not available for isoc communication.
	err = 0;
	} else {
	for (i = 0; i < SND_OXFW_STREAM_FORMAT_ENTRIES; i++) {
	format = oxfw->tx_stream_formats[i];
	if (format == NULL)
	continue;
	err = snd_oxfw_stream_parse_format(format,
	&formation);
	if (err < 0)
	continue;

	/* Add one MIDI port. */
	if (formation.midi > 0)
	oxfw->midi_input_ports = 1;
	}

	oxfw->has_output = true;
	}
	}

	/* use iPCR[0] if exists */
	if (plugs[0] > 0) {
	err = fill_stream_formats(oxfw, AVC_GENERAL_PLUG_DIR_IN, 0);
	if (err < 0) {
	if (err != -ENXIO)
	return err;

	// The iPCR is not available for isoc communication.
	err = 0;
	} else {
	for (i = 0; i < SND_OXFW_STREAM_FORMAT_ENTRIES; i++) {
	format = oxfw->rx_stream_formats[i];
	if (format == NULL)
	continue;
	err = snd_oxfw_stream_parse_format(format,
	&formation);
	if (err < 0)
	continue;

	/* Add one MIDI port. */
	if (formation.midi > 0)
	oxfw->midi_output_ports = 1;
	}

	oxfw->has_input = true;
	}
	}
	end:
	return err;
	}

	void snd_oxfw_stream_lock_changed(struct snd_oxfw *oxfw)
	{
	oxfw->dev_lock_changed = true;
	wake_up(&oxfw->hwdep_wait);
	}

	int snd_oxfw_stream_lock_try(struct snd_oxfw *oxfw)
	{
	int err;

	spin_lock_irq(&oxfw->lock);

	/* user land lock this */
	if (oxfw->dev_lock_count < 0) {
	err = -EBUSY;
	goto end;
	}

	/* this is the first time */
	if (oxfw->dev_lock_count++ == 0)
	snd_oxfw_stream_lock_changed(oxfw);
	err = 0;
	end:
	spin_unlock_irq(&oxfw->lock);
	return err;
	}

	void snd_oxfw_stream_lock_release(struct snd_oxfw *oxfw)
	{
	spin_lock_irq(&oxfw->lock);

	if (WARN_ON(oxfw->dev_lock_count <= 0))
	goto end;
	if (--oxfw->dev_lock_count == 0)
	snd_oxfw_stream_lock_changed(oxfw);
	end:
	spin_unlock_irq(&oxfw->lock);
	}