[ALSA] Add documentation for HDSP MADI

Documentation
Added documentation for HDSP MADI driver by Winfried Ritsch.
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

Documentation/sound/alsa/ALSA-Configuration.txt

@@ -674,6 +674,17 @@ Prior to version 0.9.0rc4 options had a 'snd_' prefix. This was removed.
           stage of boot sequence.  See "Early Buffer Allocation"
 	  section.
 
+  Module snd-hdspm
+  ----------------
+
+    Module for RME HDSP MADI board.
+
+    precise_ptr		- Enable precise pointer, or disable.
+    line_outs_monitor	- Send playback streams to analog outs by default.
+    enable_monitor	- Enable Analog Out on Channel 63/64 by default.
+
+    See hdspm.txt for details.
+
   Module snd-ice1712
   ------------------
 

Documentation/sound/alsa/hdspm.txt

+Software Interface ALSA-DSP MADI Driver 
+
+(translated from German, so no good English ;-), 
+2004 - winfried ritsch
+
+
+
+ Full functionality has been added to the driver. Since some of
+ the Controls and startup-options  are ALSA-Standard and only the
+ special Controls are described and discussed below.
+
+
+ hardware functionality:
+
+   
+   Audio transmission:
+
+     number of channels --  depends on transmission mode
+
+		The number of channels chosen is from 1..Nmax. The reason to
+		use for a lower number of channels is only resource allocation,
+		since unused DMA channels are disabled and less memory is
+		allocated. So also the throughput of the PCI system can be
+		scaled. (Only important for low performance boards).
+
+       Single Speed -- 1..64 channels 
+
+		 (Note: Choosing the 56channel mode for transmission or as
+		 receiver, only 56 are transmitted/received over the MADI, but
+		 all 64 channels are available for the mixer, so channel count
+		 for the driver)
+
+       Double Speed -- 1..32 channels
+
+		 Note: Choosing the 56-channel mode for
+		 transmission/receive-mode , only 28 are transmitted/received
+		 over the MADI, but all 32 channels are available for the mixer,
+		 so channel count for the driver
+
+
+       Quad Speed -- 1..16 channels 
+
+		 Note: Choosing the 56-channel mode for
+		 transmission/receive-mode , only 14 are transmitted/received
+		 over the MADI, but all 16 channels are available for the mixer,
+		 so channel count for the driver
+
+     Format -- signed 32 Bit Little Endian (SNDRV_PCM_FMTBIT_S32_LE)
+
+     Sample Rates --
+
+       Single Speed -- 32000, 44100, 48000
+
+       Double Speed -- 64000, 88200, 96000 (untested)
+
+       Quad Speed -- 128000, 176400, 192000 (untested)
+
+     access-mode -- MMAP (memory mapped), Not interleaved
+     (PCM_NON-INTERLEAVED)
+
+     buffer-sizes -- 64,128,256,512,1024,2048,8192 Samples
+
+     fragments -- 2
+
+     Hardware-pointer -- 2 Modi
+
+
+		 The Card supports the readout of the actual Buffer-pointer,
+		 where DMA reads/writes. Since of the bulk mode of PCI it is only
+		 64 Byte accurate. SO it is not really usable for the
+		 ALSA-mid-level functions (here the buffer-ID gives a better
+		 result), but if MMAP is used by the application. Therefore it
+		 can be configured at load-time with the parameter
+		 precise-pointer.
+
+
+		 (Hint: Experimenting I found that the pointer is maximum 64 to
+		 large never to small. So if you subtract 64 you always have a
+		 safe pointer for writing, which is used on this mode inside
+		 ALSA. In theory now you can get now a latency as low as 16
+		 Samples, which is a quarter of the interrupt possibilities.)
+
+       Precise Pointer -- off
+					interrupt used for pointer-calculation
+
+       Precise Pointer -- on
+					hardware pointer used.
+
+   Controller:
+
+
+	  Since DSP-MADI-Mixer has 8152 Fader, it does not make sense to
+	  use the standard mixer-controls, since this would break most of
+	  (especially graphic) ALSA-Mixer GUIs. So Mixer control has be
+	  provided by a 2-dimensional controller using the
+	  hwdep-interface. 
+
+     Also all 128+256 Peak and RMS-Meter can be accessed via the
+     hwdep-interface. Since it could be a performance problem always
+     copying and converting Peak and RMS-Levels even if you just need
+     one, I decided to export the hardware structure, so that of
+     needed some driver-guru can implement a memory-mapping of mixer
+     or peak-meters over ioctl, or also to do only copying and no
+     conversion. A test-application shows the usage of the controller.
+
+    Latency Controls --- not implemented !!!
+
+
+	   Note: Within the windows-driver the latency is accessible of a
+	   control-panel, but buffer-sizes are controlled with ALSA from
+	   hwparams-calls and should not be changed in run-state, I did not
+	   implement it here.
+
+
+    System Clock -- suspended !!!!
+
+        Name -- "System Clock Mode"
+
+        Access -- Read Write
+
+        Values -- "Master" "Slave"
+
+
+		  !!!! This is a hardware-function but is in conflict with the
+		  Clock-source controller, which is a kind of ALSA-standard. I
+		  makes sense to set the card to a special mode (master at some
+		  frequency or slave), since even not using an Audio-application
+		  a studio should have working synchronisations setup. So use
+		  Clock-source-controller instead !!!!
+
+    Clock Source  
+
+       Name -- "Sample Clock Source"
+
+       Access -- Read Write
+
+       Values -- "AutoSync", "Internal 32.0 kHz", "Internal 44.1 kHz",
+       "Internal 48.0 kHz", "Internal 64.0 kHz", "Internal 88.2 kHz",
+       "Internal 96.0 kHz"
+
+		 Choose between Master at a specific Frequency and so also the
+		 Speed-mode or Slave (Autosync). Also see  "Preferred Sync Ref"
+
+
+       !!!! This is no pure hardware function but was implemented by
+       ALSA by some ALSA-drivers before, so I use it also. !!!
+
+
+    Preferred Sync Ref
+
+       Name -- "Preferred Sync Reference"
+
+       Access -- Read Write
+
+       Values -- "Word" "MADI"
+
+
+		 Within the Auto-sync-Mode the preferred Sync Source can be
+		 chosen. If it is not available another is used if possible.
+
+		 Note: Since MADI has a much higher bit-rate than word-clock, the
+		 card should synchronise better in MADI Mode. But since the
+		 RME-PLL is very good, there are almost no problems with
+		 word-clock too. I never found a difference.
+
+
+    TX 64 channel --- 
+
+       Name -- "TX 64 channels mode"
+
+       Access -- Read Write
+
+       Values -- 0 1
+
+		 Using 64-channel-modus (1) or 56-channel-modus for
+		 MADI-transmission (0).
+
+
+		 Note: This control is for output only. Input-mode is detected
+		 automatically from hardware sending MADI.
+
+
+    Clear TMS ---
+
+       Name -- "Clear Track Marker"
+
+       Access -- Read Write
+
+       Values -- 0 1
+
+
+		 Don't use to lower 5 Audio-bits on AES as additional Bits.
+        
+
+    Safe Mode oder Auto Input --- 
+
+       Name -- "Safe Mode"
+
+       Access -- Read Write
+
+       Values -- 0 1
+
+       (default on)
+
+		 If on (1), then if either the optical or coaxial connection
+		 has a failure, there is a takeover to the working one, with no
+		 sample failure. Its only useful if you use the second as a
+		 backup connection.
+
+    Input --- 
+
+       Name -- "Input Select"
+
+       Access -- Read Write
+
+       Values -- optical coaxial
+
+
+		 Choosing the Input, optical or coaxial. If Safe-mode is active,
+		 this is the preferred Input.
+
+-------------- Mixer ----------------------
+
+    Mixer
+
+       Name -- "Mixer"
+
+       Access -- Read Write
+
+       Values - <channel-number 0-127> <Value 0-65535>
+
+
+		 Here as a first value the channel-index is taken to get/set the
+		 corresponding mixer channel, where 0-63 are the input to output
+		 fader and 64-127 the playback to outputs fader. Value 0
+		 is channel muted 0 and 32768 an amplification of  1.
+
+    Chn 1-64
+
+       fast mixer for the ALSA-mixer utils. The diagonal of the
+       mixer-matrix is implemented from playback to output.
+       
+
+    Line Out
+
+       Name  -- "Line Out"
+
+       Access -- Read Write
+
+       Values -- 0 1
+
+		 Switching on and off the analog out, which has nothing to do
+		 with mixing or routing. the analog outs reflects channel 63,64.
+
+
+--- information (only read access):
+ 
+    Sample Rate
+
+       Name -- "System Sample Rate"
+
+       Access -- Read-only
+
+		 getting the sample rate.
+
+
+    External Rate measured
+
+       Name -- "External Rate"
+
+       Access -- Read only
+
+
+		 Should be "Autosync Rate", but Name used is
+		 ALSA-Scheme. External Sample frequency liked used on Autosync is
+		 reported.
+
+
+    MADI Sync Status
+
+       Name -- "MADI Sync Lock Status"
+
+       Access -- Read
+
+       Values -- 0,1,2
+
+       MADI-Input is 0=Unlocked, 1=Locked, or 2=Synced.
+
+
+    Word Clock Sync Status
+
+       Name -- "Word Clock Lock Status"
+
+       Access -- Read
+
+       Values -- 0,1,2
+
+       Word Clock Input is 0=Unlocked, 1=Locked, or 2=Synced.
+
+    AutoSync
+
+       Name -- "AutoSync Reference"
+
+       Access -- Read
+
+       Values -- "WordClock", "MADI", "None"
+
+		 Sync-Reference is either "WordClock", "MADI" or none.
+
+   RX 64ch --- noch nicht implementiert
+
+       MADI-Receiver is in 64 channel mode oder 56 channel mode.
+
+
+   AB_inp   --- not tested 
+
+		 Used input for Auto-Input.
+
+
+   actual Buffer Position --- not implemented
+
+	   !!! this is a ALSA internal function, so no control is used !!!
+
+
+
+Calling Parameter:
+
+   index int array (min = 1, max = 8), 
+     "Index value for RME HDSPM interface." card-index within ALSA
+
+     note: ALSA-standard
+
+   id string array (min = 1, max = 8), 
+     "ID string for RME HDSPM interface."
+
+     note: ALSA-standard
+
+   enable int array (min = 1, max = 8), 
+     "Enable/disable specific HDSPM sound-cards."
+
+     note: ALSA-standard
+
+   precise_ptr int array (min = 1, max = 8), 
+     "Enable precise pointer, or disable."
+
+     note: Use only when the application supports this (which is a special case).
+
+   line_outs_monitor int array (min = 1, max = 8), 
+     "Send playback streams to analog outs by default."
+
+
+	  note: each playback channel is mixed to the same numbered output
+	  channel (routed). This is against the ALSA-convention, where all
+	  channels have to be muted on after loading the driver, but was
+	  used before on other cards, so i historically use it again)
+
+
+
+   enable_monitor int array (min = 1, max = 8), 
+     "Enable Analog Out on Channel 63/64 by default."
+
+      note: here the analog output is enabled (but not routed).
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