sound/usb/line6/pcm.h

   1 /*
   2  * Line 6 Linux USB driver
   3  *
   4  * Copyright (C) 2004-2010 Markus Grabner (grabner@icg.tugraz.at)
   5  *
   6  *      This program is free software; you can redistribute it and/or
   7  *      modify it under the terms of the GNU General Public License as
   8  *      published by the Free Software Foundation, version 2.
   9  *
  10  */
  11
  12 /*
  13         PCM interface to POD series devices.
  14 */
  15
  16 #ifndef PCM_H
  17 #define PCM_H
  18
  19 #include <sound/pcm.h>
  20
  21 #include "driver.h"
  22
  23 /*
  24         number of USB frames per URB
  25         The Line 6 Windows driver always transmits two frames per packet, but
  26         the Linux driver performs significantly better (i.e., lower latency)
  27         with only one frame per packet.
  28 */
  29 #define LINE6_ISO_PACKETS       1
  30
  31 /* in a "full speed" device (such as the PODxt Pro) this means 1ms,
  32  *  for "high speed" it's 1/8ms
  33  */
  34 #define LINE6_ISO_INTERVAL      1
  35
  36 #define LINE6_IMPULSE_DEFAULT_PERIOD 100
  37
  38 /*
  39         Get substream from Line 6 PCM data structure
  40 */
  41 #define get_substream(line6pcm, stream) \
  42                 (line6pcm->pcm->streams[stream].substream)
  43
  44 /*
  45         PCM mode bits.
  46
  47         There are several features of the Line 6 USB driver which require PCM
  48         data to be exchanged with the device:
  49         *) PCM playback and capture via ALSA
  50         *) software monitoring (for devices without hardware monitoring)
  51         *) optional impulse response measurement
  52         However, from the device's point of view, there is just a single
  53         capture and playback stream, which must be shared between these
  54         subsystems. It is therefore necessary to maintain the state of the
  55         subsystems with respect to PCM usage.
  56
  57         We define two bit flags, "opened" and "running", for each playback
  58         or capture stream.  Both can contain the bit flag corresponding to
  59         LINE6_STREAM_* type,
  60           LINE6_STREAM_PCM = ALSA PCM playback or capture
  61           LINE6_STREAM_MONITOR = software monitoring
  62           IMPULSE = optional impulse response measurement
  63         The opened flag indicates whether the buffer is allocated while
  64         the running flag indicates whether the stream is running.
  65
  66         For monitor or impulse operations, the driver needs to call
  67         line6_pcm_acquire() or line6_pcm_release() with the appropriate
  68         LINE6_STREAM_* flag.
  69 */
  70
  71 /* stream types */
  72 enum {
  73         LINE6_STREAM_PCM,
  74         LINE6_STREAM_MONITOR,
  75         LINE6_STREAM_IMPULSE,
  76         LINE6_STREAM_CAPTURE_HELPER,
  77 };
  78
  79 /* misc bit flags for PCM operation */
  80 enum {
  81         LINE6_FLAG_PAUSE_PLAYBACK,
  82         LINE6_FLAG_PREPARED,
  83 };
  84
  85 struct line6_pcm_properties {
  86         struct snd_pcm_hardware playback_hw, capture_hw;
  87         struct snd_pcm_hw_constraint_ratdens rates;
  88         int bytes_per_channel;
  89 };
  90
  91 struct line6_pcm_stream {
  92         /* allocated URBs */
  93         struct urb **urbs;
  94
  95         /* Temporary buffer;
  96          * Since the packet size is not known in advance, this buffer is
  97          * large enough to store maximum size packets.
  98          */
  99         unsigned char *buffer;
 100
 101         /* Free frame position in the buffer. */
 102         snd_pcm_uframes_t pos;
 103
 104         /* Count processed bytes;
 105          * This is modulo period size (to determine when a period is finished).
 106          */
 107         unsigned bytes;
 108
 109         /* Counter to create desired sample rate */
 110         unsigned count;
 111
 112         /* period size in bytes */
 113         unsigned period;
 114
 115         /* Processed frame position in the buffer;
 116          * The contents of the ring buffer have been consumed by the USB
 117          * subsystem (i.e., sent to the USB device) up to this position.
 118          */
 119         snd_pcm_uframes_t pos_done;
 120
 121         /* Bit mask of active URBs */
 122         unsigned long active_urbs;
 123
 124         /* Bit mask of URBs currently being unlinked */
 125         unsigned long unlink_urbs;
 126
 127         /* Spin lock to protect updates of the buffer positions (not contents)
 128          */
 129         spinlock_t lock;
 130
 131         /* Bit flags for operational stream types */
 132         unsigned long opened;
 133
 134         /* Bit flags for running stream types */
 135         unsigned long running;
 136
 137         int last_frame;
 138 };
 139
 140 struct snd_line6_pcm {
 141         /* Pointer back to the Line 6 driver data structure */
 142         struct usb_line6 *line6;
 143
 144         /* Properties. */
 145         struct line6_pcm_properties *properties;
 146
 147         /* ALSA pcm stream */
 148         struct snd_pcm *pcm;
 149
 150         /* protection to state changes of in/out streams */
 151         struct mutex state_mutex;
 152
 153         /* Capture and playback streams */
 154         struct line6_pcm_stream in;
 155         struct line6_pcm_stream out;
 156
 157         /* Previously captured frame (for software monitoring) */
 158         unsigned char *prev_fbuf;
 159
 160         /* Size of previously captured frame (for software monitoring/sync) */
 161         int prev_fsize;
 162
 163         /* Maximum size of USB packet */
 164         int max_packet_size_in;
 165         int max_packet_size_out;
 166
 167         /* PCM playback volume (left and right) */
 168         int volume_playback[2];
 169
 170         /* PCM monitor volume */
 171         int volume_monitor;
 172
 173         /* Volume of impulse response test signal (if zero, test is disabled) */
 174         int impulse_volume;
 175
 176         /* Period of impulse response test signal */
 177         int impulse_period;
 178
 179         /* Counter for impulse response test signal */
 180         int impulse_count;
 181
 182         /* Several status bits (see LINE6_FLAG_*) */
 183         unsigned long flags;
 184 };
 185
 186 extern int line6_init_pcm(struct usb_line6 *line6,
 187                           struct line6_pcm_properties *properties);
 188 extern int snd_line6_trigger(struct snd_pcm_substream *substream, int cmd);
 189 extern int snd_line6_prepare(struct snd_pcm_substream *substream);
 190 extern int snd_line6_hw_params(struct snd_pcm_substream *substream,
 191                                struct snd_pcm_hw_params *hw_params);
 192 extern int snd_line6_hw_free(struct snd_pcm_substream *substream);
 193 extern snd_pcm_uframes_t snd_line6_pointer(struct snd_pcm_substream *substream);
 194 extern void line6_pcm_disconnect(struct snd_line6_pcm *line6pcm);
 195 extern int line6_pcm_acquire(struct snd_line6_pcm *line6pcm, int type,
 196                                bool start);
 197 extern void line6_pcm_release(struct snd_line6_pcm *line6pcm, int type);
 198
 199 #endif