200 lines
5.3 KiB
C
200 lines
5.3 KiB
C
/*
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* Line 6 Linux USB driver
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*
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* Copyright (C) 2004-2010 Markus Grabner (grabner@icg.tugraz.at)
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation, version 2.
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*
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*/
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/*
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PCM interface to POD series devices.
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*/
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#ifndef PCM_H
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#define PCM_H
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#include <sound/pcm.h>
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#include "driver.h"
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/*
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number of USB frames per URB
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The Line 6 Windows driver always transmits two frames per packet, but
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the Linux driver performs significantly better (i.e., lower latency)
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with only one frame per packet.
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*/
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#define LINE6_ISO_PACKETS 1
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/* in a "full speed" device (such as the PODxt Pro) this means 1ms,
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* for "high speed" it's 1/8ms
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*/
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#define LINE6_ISO_INTERVAL 1
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#define LINE6_IMPULSE_DEFAULT_PERIOD 100
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/*
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Get substream from Line 6 PCM data structure
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*/
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#define get_substream(line6pcm, stream) \
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(line6pcm->pcm->streams[stream].substream)
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/*
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PCM mode bits.
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There are several features of the Line 6 USB driver which require PCM
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data to be exchanged with the device:
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*) PCM playback and capture via ALSA
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*) software monitoring (for devices without hardware monitoring)
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*) optional impulse response measurement
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However, from the device's point of view, there is just a single
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capture and playback stream, which must be shared between these
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subsystems. It is therefore necessary to maintain the state of the
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subsystems with respect to PCM usage.
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We define two bit flags, "opened" and "running", for each playback
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or capture stream. Both can contain the bit flag corresponding to
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LINE6_STREAM_* type,
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LINE6_STREAM_PCM = ALSA PCM playback or capture
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LINE6_STREAM_MONITOR = software monitoring
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IMPULSE = optional impulse response measurement
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The opened flag indicates whether the buffer is allocated while
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the running flag indicates whether the stream is running.
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For monitor or impulse operations, the driver needs to call
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line6_pcm_acquire() or line6_pcm_release() with the appropriate
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LINE6_STREAM_* flag.
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*/
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/* stream types */
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enum {
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LINE6_STREAM_PCM,
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LINE6_STREAM_MONITOR,
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LINE6_STREAM_IMPULSE,
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LINE6_STREAM_CAPTURE_HELPER,
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};
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/* misc bit flags for PCM operation */
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enum {
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LINE6_FLAG_PAUSE_PLAYBACK,
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LINE6_FLAG_PREPARED,
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};
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struct line6_pcm_properties {
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struct snd_pcm_hardware playback_hw, capture_hw;
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struct snd_pcm_hw_constraint_ratdens rates;
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int bytes_per_channel;
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};
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struct line6_pcm_stream {
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/* allocated URBs */
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struct urb **urbs;
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/* Temporary buffer;
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* Since the packet size is not known in advance, this buffer is
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* large enough to store maximum size packets.
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*/
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unsigned char *buffer;
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/* Free frame position in the buffer. */
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snd_pcm_uframes_t pos;
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/* Count processed bytes;
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* This is modulo period size (to determine when a period is finished).
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*/
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unsigned bytes;
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/* Counter to create desired sample rate */
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unsigned count;
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/* period size in bytes */
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unsigned period;
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/* Processed frame position in the buffer;
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* The contents of the ring buffer have been consumed by the USB
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* subsystem (i.e., sent to the USB device) up to this position.
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*/
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snd_pcm_uframes_t pos_done;
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/* Bit mask of active URBs */
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unsigned long active_urbs;
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/* Bit mask of URBs currently being unlinked */
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unsigned long unlink_urbs;
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/* Spin lock to protect updates of the buffer positions (not contents)
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*/
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spinlock_t lock;
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/* Bit flags for operational stream types */
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unsigned long opened;
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/* Bit flags for running stream types */
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unsigned long running;
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int last_frame;
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};
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struct snd_line6_pcm {
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/* Pointer back to the Line 6 driver data structure */
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struct usb_line6 *line6;
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/* Properties. */
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struct line6_pcm_properties *properties;
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/* ALSA pcm stream */
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struct snd_pcm *pcm;
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/* protection to state changes of in/out streams */
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struct mutex state_mutex;
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/* Capture and playback streams */
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struct line6_pcm_stream in;
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struct line6_pcm_stream out;
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/* Previously captured frame (for software monitoring) */
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unsigned char *prev_fbuf;
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/* Size of previously captured frame (for software monitoring/sync) */
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int prev_fsize;
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/* Maximum size of USB packet */
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int max_packet_size_in;
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int max_packet_size_out;
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/* PCM playback volume (left and right) */
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int volume_playback[2];
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/* PCM monitor volume */
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int volume_monitor;
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/* Volume of impulse response test signal (if zero, test is disabled) */
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int impulse_volume;
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/* Period of impulse response test signal */
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int impulse_period;
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/* Counter for impulse response test signal */
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int impulse_count;
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/* Several status bits (see LINE6_FLAG_*) */
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unsigned long flags;
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};
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extern int line6_init_pcm(struct usb_line6 *line6,
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struct line6_pcm_properties *properties);
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extern int snd_line6_trigger(struct snd_pcm_substream *substream, int cmd);
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extern int snd_line6_prepare(struct snd_pcm_substream *substream);
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extern int snd_line6_hw_params(struct snd_pcm_substream *substream,
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struct snd_pcm_hw_params *hw_params);
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extern int snd_line6_hw_free(struct snd_pcm_substream *substream);
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extern snd_pcm_uframes_t snd_line6_pointer(struct snd_pcm_substream *substream);
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extern void line6_pcm_disconnect(struct snd_line6_pcm *line6pcm);
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extern int line6_pcm_acquire(struct snd_line6_pcm *line6pcm, int type,
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bool start);
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extern void line6_pcm_release(struct snd_line6_pcm *line6pcm, int type);
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#endif
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