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ucm: add initial doxygen documenation
This is an attempt to explain the UCM in a more verbose way. BugLink: https://github.com/alsa-project/alsa-ucm-conf/issues/103 Signed-off-by: Jaroslav Kysela <perex@perex.cz>
This commit is contained in:
Jaroslav Kysela
parent
ebb8a6c7a1
commit
2623e4bb76
3 changed files with 572 additions and 38 deletions
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@ -1,57 +1,60 @@
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/*! \mainpage Index Preamble and License
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/*! \mainpage Index, Preamble and License
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\author Jaroslav Kysela <perex@perex.cz>
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\author Abramo Bagnara <abramo@alsa-project.org>
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\author Takashi Iwai <tiwai@suse.de>
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\author Frank van de Pol <fvdpol@coil.demon.nl>
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<H2>Preface</H2>
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<P>The Advanced Linux Sound Architecture (\e ALSA) comes with a kernel
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Preface
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-------
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The Advanced Linux Sound Architecture (\e ALSA) comes with a kernel
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API and a library API. This document describes the library API and how
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it interfaces with the kernel API.</P>
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it interfaces with the kernel API.
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<H2>Documentation License</H2>
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### Documentation License
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<P>This documentation is free; you can redistribute it without
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any restrictions. Modifications or derived work must retain
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the copyright and list all authors.</P>
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This documentation is free; you can redistribute it without
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any restrictions. Modifications or derived work must retain
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the copyright and list all authors.
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<P>This documentation is distributed in the hope that it will be
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useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.</P>
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This documentation is distributed in the hope that it will be
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useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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<H2>API usage</H2>
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<P>Application programmers should use the library API rather than the
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API usage
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---------
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Application programmers should use the library API rather than the
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kernel API. The library offers 100% of the functionality of the kernel API,
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but adds major improvements in usability, making the application code simpler
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and better looking. In addition, future fixes or compatibility code
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may be placed in the library code instead of the kernel driver.</P>
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may be placed in the library code instead of the kernel driver.
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<H2>API links</H2>
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API links
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---------
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<UL>
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<LI>Page \ref control explains the primitive controls API.
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<LI>Page \ref control_plugins explains the design of primitive control plugins.
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<LI>Page \ref hcontrol explains the high-level primitive controls API.
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<LI>Page \ref mixer explains the mixer controls API.
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<LI>Page \ref pcm explains the design of the PCM (digital audio) API.
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<LI>Page \ref pcm_plugins explains the design of PCM (digital audio) plugins.
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<LI>Page \ref pcm_external_plugins explains the external PCM plugin SDK.
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<LI>Page \ref ctl_external_plugins explains the external control plugin SDK.
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<LI>Page \ref rawmidi explains the design of the RawMidi API.
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<LI>Page \ref timer explains the design of the Timer API.
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<LI>Page \ref seq explains the design of the Sequencer API.
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<LI>Page \ref ucm explains the use case API.
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<LI>Page \ref topology explains the DSP topology API.
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</UL>
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- Page \subpage control explains the primitive controls API.
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- Page \subpage control_plugins explains the design of primitive control plugins.
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- Page \subpage hcontrol explains the high-level primitive controls API.
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- Page \subpage mixer explains the mixer controls API.
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- Page \subpage pcm explains the design of the PCM (digital audio) API.
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- Page \subpage pcm_plugins explains the design of PCM (digital audio) plugins.
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- Page \subpage pcm_external_plugins explains the external PCM plugin SDK.
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- Page \subpage ctl_external_plugins explains the external control plugin SDK.
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- Page \subpage rawmidi explains the design of the RawMidi API.
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- Page \subpage timer explains the design of the Timer API.
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- Page \subpage seq explains the design of the Sequencer API.
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- Page \subpage ucm explains the use case API.
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- Page \subpage topology explains the DSP topology API.
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<H2>Configuration</H2>
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Configuration
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-------------
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<UL>
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<LI>Page \ref conf explains the syntax of library configuration files.
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<LI>Page \ref confarg explains the run-time argument syntax.
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<LI>Page \ref conffunc explains run-time function definitions and their usage.
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<LI>Page \ref confhooks explains run-time hook definitions and their usage.
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</UL>
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- Page \subpage conf explains the syntax of library configuration.
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- Page \subpage confarg explains the run-time argument syntax.
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- Page \subpage conffunc explains run-time function definitions and their usage.
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- Page \subpage confhooks explains run-time hook definitions and their usage.
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- Page \subpage ucm_conf explains the UCM configuration and their usage.
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*/
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@ -3,7 +3,7 @@ EXTRA_LTLIBRARIES = libucm.la
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libucm_la_SOURCES = utils.c parser.c ucm_cond.c ucm_subs.c ucm_include.c \
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ucm_regex.c ucm_exec.c main.c
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noinst_HEADERS = ucm_local.h
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noinst_HEADERS = ucm_local.h ucm_confdoc.h
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all: libucm.la
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531
src/ucm/ucm_confdoc.h
Normal file
531
src/ucm/ucm_confdoc.h
Normal file
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@ -0,0 +1,531 @@
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/*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*
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* Support for the verb/device/modifier core logic and API,
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* command line tool and file parser was kindly sponsored by
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* Texas Instruments Inc.
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* Support for multiple active modifiers and devices,
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* transition sequences, multiple client access and user defined use
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* cases was kindly sponsored by Wolfson Microelectronics PLC.
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*
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* Copyright (C) 2021 Red Hat Inc.
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* Authors: Jaroslav Kysela <perex@perex.cz>
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*/
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/**
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* \defgroup ucm_conf Use Case Configuration
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* The ALSA Use Case Configuration.
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* See \ref Usecase_conf page for more details.
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* \{
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*/
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/*! \page Usecase_conf ALSA Use Case Configuration
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The use case configuration files use \ref conf syntax to define the
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static configuration tree. This tree is evaluated (modified) at runtime
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according the conditions and dynamic variables in the configuration tree.
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The result is parsed and exported to the applications using \ref ucm API.
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### Configuration directory and main filename lookup
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The lookup paths are describen in *ucm.conf* file. The configuration
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structure looks like:
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~~~{.html}
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UseCasePath.path1 {
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Directory "conf.virt.d"
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File "${OpenName}.conf"
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}
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UseCasePath.path2 {
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Directory "external"
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File "${OpenName}.conf"
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}
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~~~
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### UCM main configuration file
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Each sound card has a master sound card file that lists all the supported
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use case verbs for that sound card. i.e.:
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~~~{.html}
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# Example master file for blah sound card
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# By Joe Blogs <joe@bloggs.org>
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# Use Case name for user interface
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Comment "Nice Abstracted Soundcard"
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# The file is divided into Use case sections. One section per use case verb.
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SectionUseCase."Voice Call" {
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File "voice_call_blah"
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Comment "Make a voice phone call."
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}
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SectionUseCase."HiFi" {
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File "hifi_blah"
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Comment "Play and record HiFi quality Music."
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}
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# Define Value defaults
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ValueDefaults {
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PlaybackChannels 4
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CaptureChannels 4
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}
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# Define boot / initialization sequence
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# This sequence is skipped, when the soundcard was already configured by system
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# (alsactl configuration was already created). The purpose is to not alter
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# ALSA card controls which may be modified by user after initial settings.
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BootSequence [
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cset "name='My control' on"
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]
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# Define fixed boot sequence
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# This sequence is always executed on boot (hotplug).
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FixedBootSequence [
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cset "name='Something to toggle' toggle"
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]
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~~~
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### UCM verb configuration file
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The verb configuration file defines devices, modifier and initialization sequences.
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It is something like a sound profile.
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~~~{.html}
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# Example Use case verb section for Voice call blah
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# By Joe Blogs <joe@blogs.com>
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# verb global section
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SectionVerb {
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# enable and disable sequences are compulsory
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EnableSequence [
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cset "name='Master Playback Switch',index=2 0,0"
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cset "name='Master Playback Volume',index=2 25,25"
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msleep 50
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cset "name='Master Playback Switch',index=2 1,1"
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cset "name='Master Playback Volume',index=2 50,50"
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]
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DisableSequence [
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cset "name='Master Playback Switch',index=2 0,0"
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cset "name='Master Playback Volume',index=2 25,25"
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msleep 50
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cset "name='Master Playback Switch',index=2 1,1"
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cset "name='Master Playback Volume',index=2 50,50"
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]
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# Optional transition verb
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TransitionSequence."ToCaseName" [
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msleep 1
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]
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# Optional TQ and device values
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Value {
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TQ HiFi
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PlaybackChannels 6
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}
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}
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# Each device is described in new section. N devices are allowed
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SectionDevice."Headphones" {
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SupportedDevice [
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"x"
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"y"
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]
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# or (not both)
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ConflictingDevice [
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"x"
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"y"
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]
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EnableSequence [
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...
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]
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DisableSequence [
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...
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]
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TransitionSequence."ToDevice" [
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...
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]
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Value {
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PlaybackVolume "name='Master Playback Volume',index=2"
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PlaybackSwitch "name='Master Playback Switch',index=2"
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PlaybackPCM "hw:${CardId},4"
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}
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}
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# Each modifier is described in new section. N modifiers are allowed
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SectionModifier."Capture Voice" {
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Comment "Record voice call"
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SupportedDevice [
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"x"
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"y"
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]
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# or (not both)
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ConflictingDevice [
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"x"
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"y"
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]
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EnableSequence [
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...
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]
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DisableSequence [
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...
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]
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TransitionSequence."ToModifierName" [
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...
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]
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# Optional TQ and ALSA PCMs
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Value {
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TQ Voice
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CapturePCM "hw:${CardId},11"
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PlaybackVolume "name='Master Playback Volume',index=2"
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PlaybackSwitch "name='Master Playback Switch',index=2"
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}
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}
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~~~
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### Sequence commands
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Command name | Description
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---------------|----------------------------------------------
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cdev ARG | ALSA control device name for snd_ctl_open()
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cset ARG | ALSA control set - snd_ctl_ascii_elem_id_parse() + snd_ctl_ascii_value_parse()
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cset-new ARG | Create new ALSA user control element - snd_ctl_ascii_elem_id_parse() + description
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ctl-remove ARG | Remove ALSA user control element - snd_ctl_ascii_elem_id_parse()
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sysw ARG | write to sysfs tree
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usleep ARG | sleep for specified amount of microseconds
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msleep ARG | sleep for specified amount of milliseconds
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exec ARG | execute a specific command (without shell - *man execv*)
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shell ARG | execute a specific command (using shell - *man system*)
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cfg-save ARG | save LibraryConfig to a file
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~~~{.html}
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# Examples
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cset "name='PCM Playback Volue',index=2 99"
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cset-new "name='Bool2' type=bool,count=2 1,0"
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cset-new "name='Enum' type=enum,labels='L1;L2;L3' 'L2'"
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ctl-remove "name='Bool2'"
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sysw "-/class/sound/ctl-led/speaker/card${CardNumber}/attach:Speaker Channel Switch"
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usleep 10
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exec "/bin/echo hello"
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shell "set"
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cfg-save "/tmp/test.conf:+pcm"
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~~~
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### Naming (devices, verbs)
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See the SND_USE_CASE_VERB constains like #SND_USE_CASE_VERB_HIFI for the full list of known verbs.
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See the SND_USE_CASE_DEV constants like #SND_USE_CASE_DEV_SPEAKER for the full list of known devices.
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If multiple devices with the same name exists, the number suffixes should
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be added to these names like HDMI1,HDMI2,HDMI3 etc. No number gaps are
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allowed. The names with numbers must be continuous. It is allowed to put
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a whitespace between name and index (like 'Line 1') for the better
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readability. The device names 'Line 1' and 'Line1' are equal for
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this purpose.
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If EnableSequence/DisableSequence controls independent paths in the hardware
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it is also recommended to split playback and capture UCM devices and use
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the number suffixes. Example use case: Use the integrated microphone
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in the laptop instead the microphone in headphones.
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The preference of the devices is determined by the priority value (higher value = higher priority).
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See the SND_USE_CASE_MOD constants like #SND_USE_CASE_MOD_ECHO_REF for the full list of known modifiers.
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### Boot (alsactl)
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The *FixedBootSequence* is executed at each boot. The *BootSequence* is executed only
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if the card's configuration is missing. The purpose is to let the users modify the
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configuration like volumes or switches. The alsactl ensures the persistency (store
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the state of the controls to the /var tree and loads the previous state in the next
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boot).
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### Device volume
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It is expected that the applications handle the volume settings. It is not recommended
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to set the fixed values for the volume settings to the Enable / Disable sequences for
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verbs or devices, if the device exports the hardware volume (MixerElem or Volume/Switch
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values). The default volume settings should be set in the *BootSequence*.
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### Dynamic configuration tree
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The evaluation order may look a bit different from the user perspective.
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At first, the standard alsa-lib configuration tree is parsed. All other
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layers on top are working with this tree. It may shift / move the configuration
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blocks from the configuration files as they are placed to the tree internally.
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~~~{.html}
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Example configuration | Parsed static tree | Identical static tree
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----------------------------+-------------------------+-------------------------------
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If.1 { | If { | If.1.True.Define.VAR "A"
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True.Define.VAR "A" | 1.True.Define.VAR "A" | If.2.True.Define.VAR "C"
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} | 2.True.Define.VAR "C" | Define.VAR "B"
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Define.VAR "B" | } |
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If.2 { | Define.VAR "B" |
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True.Define.VAR "C" | |
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} | |
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~~~
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Even if one or both conditions are evaluated as true, the variable _VAR_ will
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be evaluated always as **B** because the first _If_ block was before the non-nested
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_Define_ . The second _If_ block was appended to the first _If_ block (before
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_Define_ in the configuration tree) in the text configuration parser.
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### Syntax
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Unless described, the syntax version 4 is used.
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~~~
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Syntax 4
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~~~
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### Include
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There are two ways to include other configuration files.
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#### Static include
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The static include is inherited from the standard alsa-lib configuration
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syntax. It can be placed anywhere in the configuration files. The search
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path is composed from the root alsa configuration path (usually
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_/usr/share/alsa_) and _ucm2_ directory.
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~~~{.html}
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<some/path/file.conf> # include file using the search path
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</absolute/path/file.conf> # include file using the absolute path
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~~~
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#### Lazy include
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The lazy include is evaluated at runtime. The root path is the ucm2
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tree. The absolute include appends the ucm2 absolute path to the
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specified path. The relative include is relative to the file which
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contains the _Include_ configuration block.
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~~~{.html}
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Include.id1.File "/some/path/file.conf" # absolute include (in the ucm2 tree)
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Include.id2.File "subdir/file.conf" # relative include to the current configuration directory (UseCasePath)
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~~~
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### Configuration tree evaluation
|
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The evaluation of the static configuration tree is proceed in
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the specific order (see table bellow). When the dynamic configuration
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tree changes, the evaluation sequence is restarted to evaluate
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all possible changes (new *Define* or *Include* or *If* blocks).
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Evaluation order | Configuration block | Evaluation restart
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------------------:|---------------------|--------------------
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1 | Define | No
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2 | Include | Yes
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3 | If | Yes
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### Substitutions
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The dynamic tree identifiers and assigned values in the configuration tree are
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substituted. The substitutes strings are in the table bellow.
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Substituted string | Value
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---------------------|---------------------
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${OpenName} | Original UCM card name (passed to snd_use_case_mgr_open())
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${ConfLibDir} | Library top-level configuration directory (e.g. /usr/share/alsa)
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${ConfTopDir} | Top-level UCM configuration directory (e.g. /usr/share/alsa/ucm2)
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||||
${ConfDir} | Card's UCM configuration directory (e.g. /usr/share/alsa/ucm2/conf.d/USB-Audio)
|
||||
${ConfName} | Configuration name (e.g. USB-Audio.conf)
|
||||
${CardNumber} | Real ALSA card number (or empty string for the virtual UCM card)
|
||||
${CardId} | ALSA card identifier (see snd_ctl_card_info_get_id())
|
||||
${CardDriver} | ALSA card driver (see snd_ctl_card_info_get_driver())
|
||||
${CardName} | ALSA card name (see snd_ctl_card_info_get_name())
|
||||
${CardLongName} | ALSA card long name (see snd_ctl_card_info_get_longname())
|
||||
${CardComponents} | ALSA card components (see snd_ctl_card_info_get_components())
|
||||
${env:<str>} | Environment variable <str>
|
||||
${sys:<str>} | Contents of sysfs file <str>
|
||||
${var:<str>} | UCM parser variable (set using a _Define_ block)
|
||||
${eval:<str>} | Evaluate expression like *($var+2)/3* [**Syntax 5**]
|
||||
${find-card:<str>} | Find a card - see _Find card substitution_ section
|
||||
${find-device:<str>} | Find a device - see _Find device substitution_ section
|
||||
|
||||
#### Find card substitution
|
||||
|
||||
This substitutions finds the ALSA card and returns the appropriate identifier or
|
||||
the card number (see return argument).
|
||||
|
||||
Usage example:
|
||||
|
||||
~~~{.html}
|
||||
${find-card:field=name,regex='^acp$',return=number}
|
||||
~~~
|
||||
|
||||
Arguments:
|
||||
|
||||
Argument | Description
|
||||
---------------------|-----------------------
|
||||
return | return value type (id, number), id is the default
|
||||
field | field for the lookup (id, driver, name, longname, mixername, components)
|
||||
regex | regex string for the field match
|
||||
|
||||
#### Find device substitution
|
||||
|
||||
Usage example:
|
||||
|
||||
~~~{.html}
|
||||
${find-device:type=pcm,field=name,regex='DMIC'}
|
||||
~~~
|
||||
|
||||
Arguments:
|
||||
|
||||
Argument | Description
|
||||
---------------------|-----------------------
|
||||
type | device type (pcm)
|
||||
stream | stream type (playback, capture), playback is default
|
||||
field | field for the lookup (id, name, subname)
|
||||
regex | regex string for the field match
|
||||
|
||||
|
||||
### Variable defines
|
||||
|
||||
The variables can be defined and altered with the *Define* or *DefineRegex* blocks.
|
||||
The *Define* block looks like:
|
||||
|
||||
~~~{.html}
|
||||
Define {
|
||||
variable1 "a"
|
||||
variable2 "b"
|
||||
}
|
||||
~~~
|
||||
|
||||
The *DefineRegex* allows substring extraction like:
|
||||
|
||||
~~~{.html}
|
||||
DefineRegex.rval {
|
||||
Regex "(hello)|(regex)"
|
||||
String "hello, it's my regex"
|
||||
}
|
||||
~~~
|
||||
|
||||
The result will be stored to variables *rval1* as *hello* and *rval2* as *regex* (every matched
|
||||
substrings are stored to a separate variable with the sequence number postfix.
|
||||
|
||||
Variables can be substituted using the `${var:rval1}` reference for example.
|
||||
|
||||
### Conditions
|
||||
|
||||
The configuration tree evaluation supports the conditions - *If* blocks. Each *If* blocks
|
||||
must define a *Condition* block and *True* or *False* blocks or both. The *True* or *False*
|
||||
blocks will be merged to the parent tree (where the *If* block is defined) when
|
||||
the *Condition* is evaluated.
|
||||
|
||||
Example:
|
||||
|
||||
~~~{.html}
|
||||
If.uniqueid {
|
||||
Condition {
|
||||
Type String
|
||||
Haystack "abcd"
|
||||
Needle "a"
|
||||
}
|
||||
True {
|
||||
Define.a a
|
||||
define.b b
|
||||
}
|
||||
}
|
||||
~~~
|
||||
|
||||
#### True (Type AlwaysTrue)
|
||||
|
||||
Execute only *True* block. It may be used to change the evaluation order as
|
||||
explained in the *Configuration Tree* paragraph.
|
||||
|
||||
#### String is empty (Type String)
|
||||
|
||||
Field | Description
|
||||
---------------------|-----------------------
|
||||
Empty | string
|
||||
|
||||
#### Strings are equal (Type String)
|
||||
|
||||
Field | Description
|
||||
---------------------|-----------------------
|
||||
String1 | string
|
||||
String2 | substring in string
|
||||
|
||||
#### Substring is present (Type String)
|
||||
|
||||
Field | Description
|
||||
---------------------|-----------------------
|
||||
Haystack | string
|
||||
Needle | substring in string
|
||||
|
||||
#### Regex match (Type RegexMatch)
|
||||
|
||||
Field | Description
|
||||
---------------------|-----------------------
|
||||
String | string
|
||||
Regex | regex expression (extended posix, ignore case)
|
||||
|
||||
#### ALSA control element exists (Type ControlExists)
|
||||
|
||||
Field | Description
|
||||
---------------------|-----------------------
|
||||
Device | ALSA control device (see snd_ctl_open())
|
||||
Control | control in ASCII (parsed using snd_ctl_ascii_elem_id_parse())
|
||||
ControlEnum | value for the enum control (optional)
|
||||
|
||||
Example:
|
||||
|
||||
~~~{.html}
|
||||
If.fmic {
|
||||
Condition {
|
||||
Type ControlExists
|
||||
Control "name='Front Mic Playback Switch'"
|
||||
}
|
||||
True {
|
||||
...
|
||||
}
|
||||
}
|
||||
~~~
|
||||
|
||||
|
||||
*/
|
||||
|
||||
/**
|
||||
\}
|
||||
*/
|
||||
Loading…
Add table
Add a link
Reference in a new issue