ALSA project - the C library reference
 All Data Structures Files Functions Variables Typedefs Enumerations Enumerator Macros Groups Pages
Data Structures | Macros | Typedefs | Enumerations | Functions
Topology Interface

Data Structures

struct  snd_tplg_tlv_template
 Template type for all TLV objects. More...
struct  snd_tplg_tlv_dbscale_template
 Template type for TLV Scale objects. More...
struct  snd_tplg_channel_elem
struct  snd_tplg_channel_map_template
 Template type for channel mapping. More...
struct  snd_tplg_pdata_template
 Template type for private data objects. More...
struct  snd_tplg_io_ops_template
 Template type for object operations mapping. More...
struct  snd_tplg_ctl_template
 Template type for control objects. More...
struct  snd_tplg_mixer_template
 Template type for mixer control objects. More...
struct  snd_tplg_enum_template
 Template type for enumerated control objects. More...
struct  snd_tplg_bytes_template
 Template type for TLV Scale objects. More...
struct  snd_tplg_graph_elem
 Template type for single DAPM graph element. More...
struct  snd_tplg_graph_template
 Template type for array of DAPM graph elements. More...
struct  snd_tplg_widget_template
 Template type for DAPM widget objects. More...
struct  snd_tplg_stream_template
 Stream configurations. More...
struct  snd_tplg_stream_caps_template
 Stream Capabilities. More...
struct  snd_tplg_pcm_template
 Template type for PCM (FE DAI & DAI links). More...
struct  snd_tplg_hw_config_template
 Template type to describe a physical link runtime supported hardware config, i.e. hardware audio formats. More...
struct  snd_tplg_dai_template
 Template type for physical DAI. It can be used to configure backend DAIs for DPCM. More...
struct  snd_tplg_link_template
 Template type for physical DAI Links. More...
struct  snd_tplg_obj_template_t
struct  snd_tplg_channel_template
 Template type for single channel mapping. More...
struct  snd_tplg_obj_template
 Generic Template Object. More...

Macros

#define SND_TPLG_MAX_CHAN   8
#define SND_TPLG_INDEX_ALL   0

Typedefs

typedef struct snd_tplg snd_tplg_t

Enumerations

enum  snd_tplg_type {
  SND_TPLG_TYPE_TLV = 0, SND_TPLG_TYPE_MIXER, SND_TPLG_TYPE_ENUM, SND_TPLG_TYPE_TEXT,
  SND_TPLG_TYPE_DATA, SND_TPLG_TYPE_BYTES, SND_TPLG_TYPE_STREAM_CONFIG, SND_TPLG_TYPE_STREAM_CAPS,
  SND_TPLG_TYPE_PCM, SND_TPLG_TYPE_DAPM_WIDGET, SND_TPLG_TYPE_DAPM_GRAPH, SND_TPLG_TYPE_BE,
  SND_TPLG_TYPE_CC, SND_TPLG_TYPE_MANIFEST, SND_TPLG_TYPE_TOKEN, SND_TPLG_TYPE_TUPLE,
  SND_TPLG_TYPE_LINK, SND_TPLG_TYPE_HW_CONFIG, SND_TPLG_TYPE_DAI
}

Functions

snd_tplg_tsnd_tplg_new (void)
 Create a new topology parser instance.
void snd_tplg_free (snd_tplg_t *tplg)
 Free a topology parser instance.
int snd_tplg_build_file (snd_tplg_t *tplg, const char *infile, const char *outfile)
 Parse and build topology text file into binary file.
void snd_tplg_verbose (snd_tplg_t *tplg, int verbose)
 Enable verbose reporting of binary file output.
int snd_tplg_add_object (snd_tplg_t *tplg, snd_tplg_obj_template_t *t)
 Register topology template object.
int snd_tplg_build (snd_tplg_t *tplg, const char *outfile)
 Build all registered topology data into binary file.
int snd_tplg_set_manifest_data (snd_tplg_t *tplg, const void *data, int len)
 Attach private data to topology manifest.
int snd_tplg_set_version (snd_tplg_t *tplg, unsigned int version)
 Set an optional vendor specific version number.

Detailed Description

ALSA Topology Interface

The topology interface allows developers to define DSP topologies in a text file format and to convert the text topology to a binary topology representation that can be understood by the kernel. The topology core currently recognises the following object types :-

Topology File Format

The topology text format uses the standard ALSA configuration file format to describe each topology object type. This allows topology objects to include other topology objects as part of their definition. i.e. a TLV data object can be shared amongst many control objects that use the same TLV data.

Controls

Topology audio controls can belong to three different types :-

Each control type can contain TLV data, private data, operations and also belong to widget objects.
Control Operations
Driver Kcontrol callback info(), get() and put() operations are mapped with the CTL ops section in topology configuration files. The ctl ops section can assign operations using the standard names (listed below) for the standard kcontrol types or use ID numbers (>256) to map to bespoke driver controls.
        ops."ctl" {
                info "volsw"
                get "257"
                put "257"
        }
   
This mapping shows info() using the standard "volsw" info callback whilst the get() and put() are mapped to bespoke driver callbacks.
The Standard operations names for control get(), put() and info calls are :-

Control Access
Controls access can be specified using the "access" section. If no "access" section is defined then default RW access flags are set for normal and TLV controls.
        access [
                read
                write
                tlv_command
        ]
   
The standard access flags are as follows :-

Control TLV Data
Controls can also use TLV data to represent dB information. This can be done by defining a TLV section and using the TLV section within the control. The TLV data for DBScale types are defined as follows :-
        scale {
                min "-9000"
                step "300"
                mute "1"
        }
   
Where the meanings and values for min, step and mute are exactly the same as defined in driver code.
Control Channel Mapping
Controls can also specify which channels they are mapped with. This is useful for userspace as it allows applications to determine the correct control channel for Left and Right etc. Channel maps are defined as follows :-
        channel."name" {
                reg "0"
                shift "0"
        }
   
The channel map reg is the register offset for the control, shift is the bit shift within the register for the channel and the section name is the channel name and can be one of the following :-
  • mono # mono stream
  • fl # front left
  • fr # front right
  • rl # rear left
  • rr # rear right
  • fc # front center
  • lfe # LFE
  • sl # side left
  • sr # side right
  • rc # rear center
  • flc # front left center
  • frc # front right center
  • rlc # rear left center
  • rrc # rear right center
  • flw # front left wide
  • frw # front right wide
  • flh # front left high
  • fch # front center high
  • frh # front right high
  • tc # top center
  • tfl # top front left
  • tfr # top front right
  • tfc # top front center
  • trl # top rear left
  • trr # top rear right
  • trc # top rear center
  • tflc # top front left center
  • tfrc # top front right center
  • tsl # top side left
  • tsr # top side right
  • llfe # left LFE
  • rlfe # right LFE
  • bc # bottom center
  • blc # bottom left center
  • brc # bottom right center
    
Control Private Data
   Controls can also have private data. This can be done by defining a private
   data section and including the section within the control. The private data
   section is defined as follows :-
   
   SectionData."pdata for EQU1" {
        file "/path/to/file"
        bytes "0x12,0x34,0x56,0x78"
        shorts "0x1122,0x3344,0x5566,0x7788"
        words "0xaabbccdd,0x11223344,0x66aa77bb,0xefef1234"
        tuples "section id of the vendor tuples"
   };
   

The file, bytes, shorts, words and tuples keywords are all mutually exclusive as the private data should only be taken from one source. The private data can either be read from a separate file or defined in the topology file using the bytes, shorts, words or tuples keywords. The keyword tuples is to define vendor specific tuples. Please refer to section Vendor Tokens and Vendor tuples.

   It's easy to use a vendor tuples object to define a C structure instance.
   And a data section can include multiple vendor tuples objects:
   
   SectionData."data element name" {
        index "1"       #Index number
        tuples [
                "id of the 1st vendor tuples section"
                "id of the 2nd vendor tuples section"
                ...
        ]
   };
   
   
How to define an element with private data
   An element can refer to a single data section or multiple data
   sections.
   
To refer to a single data section:
   
   Sectionxxx."element name" {
      ...
        data "name of data section"             # optional private data
   }
   
   
To refer to multiple data sections:
   
   Sectionxxx."element name" {
        ...
        data [                                          # optional private data
                "name of 1st data section"
                "name of 2nd data section"
                ...
        ]
   }
   

And data of these sections will be merged in the same order as they are in the list, as the element's private data for kernel.

   
Vendor Tokens
A vendor token list is defined as a new section. Each token element is a pair of string ID and integer value. And both the ID and value are vendor-specific.
   SectionVendorTokens."id of the vendor tokens" {
        comment "optional comments"
        VENDOR_TOKEN_ID1 "1"
        VENDOR_TOKEN_ID2 "2"
        VENDOR_TOKEN_ID3 "3"
        ...
   }
   
Vendor Tuples
Vendor tuples are defined as a new section. It contains a reference to a vendor token list and several tuple arrays. All arrays share a vendor token list, defined by the tokens keyword. Each tuple array is for a specific type, defined by the string following the tuples keyword. Supported types are: string, uuid, bool, byte, short and word.
   SectionVendorTuples."id of the vendor tuples" {
        tokens "id of the vendor tokens"
        tuples."string" {
                VENDOR_TOKEN_ID1 "character string"
                ...
        }
        tuples."uuid" {                 # 16 characters separated by commas
                VENDOR_TOKEN_ID2 "0x01,0x02,...,0x0f"
                ...
        }
        tuples."bool" {
                VENDOR_TOKEN_ID3 "true/false"
                ...
        }
        tuples."byte" {
                VENDOR_TOKEN_ID4 "0x11"
                VENDOR_TOKEN_ID5 "0x22"
                ...
        }
        tuples."short" {
                VENDOR_TOKEN_ID6 "0x1122"
                VENDOR_TOKEN_ID7 "0x3344"
                ...
        }
        tuples."word" {
                VENDOR_TOKEN_ID8 "0x11223344"
                VENDOR_TOKEN_ID9 "0x55667788"
                ...
        }
   }
   

To define multiple vendor tuples of same type, please append some characters after the type string ("string", "uuid", "bool", "byte", "short" or "word"), to avoid ID duplication in the SectionVendorTuples.
The parser will check the first few characters in ID to get the tuple type. Here is an example:

   SectionVendorTuples."id of the vendor tuples" {
      ...
        tuples."word.module0" {
                VENDOR_TOKEN_PARAM_ID1 "0x00112233"
                VENDOR_TOKEN_PARAM_ID2 "0x44556677"
                ...
        }
        tuples."word.module2" {
                VENDOR_TOKEN_PARAM_ID1 "0x11223344"
                VENDOR_TOKEN_PARAM_ID2 "0x55667788"
                ...
        }
        ...
   }
   
Mixer Controls
A mixer control is defined as a new section that can include channel mapping, TLV data, callback operations and private data. The mixer section also includes a few other config options that are shown here :-
   SectionControlMixer."mixer name" {
        comment "optional comments"
        index "1"                       # Index number
        channel."name" {                # Channel maps
           ....
        }
        ops."ctl" {                     # Ops callback functions
           ....
        }
        max "32"                        # Max control value
        invert "0"                      # Whether control values are inverted
        tlv "tld_data"                  # optional TLV data
        data "pdata for mixer1"         # optional private data
   }
   
The section name is used to define the mixer name. The index number can be used to identify topology objects groups(index "0" is common, fit for all user cases).This allows driver operations on objects with index number N and can be used to add/remove pipelines of objects whilst other objects are unaffected.
Byte Controls
A byte control is defined as a new section that can include channel mapping, TLV data, callback operations and private data. The bytes section also includes a few other config options that are shown here :-
   SectionControlBytes."name" {
        comment "optional comments"
        index "1"                       # Index number
        channel."name" {                # Channel maps
           ....
        }
        ops."ctl" {                     # Ops callback functions
           ....
        }
        base "0"                        # Register base
        num_regs "16"                   # Number of registers
        mask "0xff"                     # Mask
        max "255"                       # Maximum value
        tlv "tld_data"                  # optional TLV data
        data "pdata for mixer1"         # optional private data
   }
   
Enumerated Controls
A enumerated control is defined as a new section (like mixer and byte) that can include channel mapping, callback operations, private data and text strings to represent the enumerated control options.
The text strings for the enumerated controls are defined in a separate section as follows :-
   SectionText."name" {
                Values [
                        "value1"
                        "value2"
                        "value3"
                ]
   }
   
All the enumerated text values are listed in the values list.
The enumerated control is similar to the other controls and defined as follows :-
   SectionControlMixer."name" {
        comment "optional comments"
        index "1"                       # Index number
        texts "EQU1"                    # Enumerated text items
        channel."name" {                # Channel maps
           ....
        }
        ops."ctl" {                     # Ops callback functions
           ....
        }
        data "pdata for mixer1"         # optional private data
   }
   

DAPM Graph

DAPM graphs can easily be defined using the topology file. The format is very similar to the DAPM graph kernel format. :-
   SectionGraph."dsp" {
        index "1"                       # Index number
        lines [
                "sink1, control, source1"
                "sink2, , source2"
        ]
   }
   
The lines in the graph are defined as a variable size list of sinks, controls and sources. The control name is optional as some graph lines have no associated controls. The section name can be used to differentiate the graph with other graphs, it's not used by the kernel atm.

DAPM Widgets

DAPM widgets are similar to controls in that they can include many other objects. Widgets can contain private data, mixer controls and enum controls.The following widget types are supported and match the driver types :- Widgets are defined as follows :-
   SectionWidget."name" {

 index "1"                       # Index number

 type "aif_in"                   # Widget type - detailed above
 stream_name "name"              # Stream name

 no_pm "true"                    # No PM control bit.
 reg "20"                        # PM bit register offset
 shift "0"                       # PM bit register shift
 invert "1                       # PM bit is inverted
 subseq "8"                      # subsequence number

 event_type "1"                  # DAPM widget event type
 event_flags "1"                 # DAPM widget event flags

 mixer "name"                    # Optional Mixer Control
 enum "name"                     # Optional Enum Control

 data "name"                     # optional private data

}

The section name is the widget name. The mixer and enum fields are mutually exclusive and used to include controls into the widget. The index and data fields are the same for widgets as they are for controls whilst the other fields map on very closely to the driver widget fields.
Widget Private Data
Widget can have private data. For the format of the private data, please refer to section Control Private Data.

PCM Capabilities

Topology can also define the PCM capabilities of front end or physical DAIs. Capabilities can be defined with the following section :-
   SectionPCMCapabilities."name" {
        formats "S24_LE,S16_LE"         # Supported formats
        rate_min "48000"                # Max supported sample rate
        rate_max "48000"                # Min supported sample rate
        channels_min "2"                # Min number of channels
        channels_max "2"                # max number of channels
   }
   

The supported formats use the same naming convention as the driver macros. The PCM capabilities name can be referred to and included by PCM and physical DAI sections.

PCM Configurations

PCM runtime configurations can be defined for playback and capture stream directions with the following section :-
   SectionPCMConfig."name" {
        config."playback" {             # playback config
                format "S16_LE"         # playback format
                rate "48000"            # playback sample rate
                channels "2"            # playback channels
                tdm_slot "0xf"          # playback TDM slot
        }
        config."capture" {              # capture config
                format "S16_LE"         # capture format
                rate "48000"            # capture sample rate
                channels "2"            # capture channels
                tdm_slot "0xf"          # capture TDM slot
        }
   }
   
The supported formats use the same naming convention as the driver macros. The PCM configuration name can be referred to and included by PCM and physical link sections.

PCM (Front-end DAI & DAI link)

PCM sections define the supported capabilities and configurations for supported playback and capture streams, names and flags for front end DAI & DAI links. Topology kernel driver will use a PCM object to create a pair of FE DAI & DAI links.
   SectionPCM."name" {
        index "1"                       # Index number
        id "0"                          # used for binding to the PCM
        dai."name of front-end DAI" {
                id "0"          # used for binding to the front-end DAI
        }
        pcm."playback" {
                capabilities "capabilities1"    # capabilities for playback
                configs [               # supported configs for playback
                        "config1"
                        "config2"
                ]
        }
        pcm."capture" {
                capabilities "capabilities2"    # capabilities for capture
                configs [               # supported configs for capture
                        "config1"
                        "config2"
                        "config3"
                ]
        }
        # Optional boolean flags
        symmetric_rates                 "true"
        symmetric_channels              "true"
        symmetric_sample_bits           "false"
        data "name"                     # optional private data
   }
   

Physical DAI Link Configurations

The runtime configurations of a physical DAI link can be defined by SectionLink.
Backend DAI links belong to physical links, and can be configured by either SectionLink or SectionBE, with same syntax. But SectionBE is deprecated atm since the internal processing is actually same.
   SectionLink."name" {
        index "1"                       # Index number
        id "0"                          # used for binding to the link
        stream_name "name"              # used for binding to the link
        hw_configs [    # runtime supported HW configurations, optional
                "config1"
                "config2"
                ...
        ]
        default_hw_conf_id "1"          #default HW config ID for init
        # Optional boolean flags
        symmetric_rates                 "true"
        symmetric_channels              "false"
        symmetric_sample_bits           "true"
        data "name"                     # optional private data
   }
   
A physical link can refer to multiple runtime supported hardware configurations, which is defined by SectionHWConfig.
   SectionHWConfig."name" {
        id "1"                          # used for binding to the config
        format "I2S"                    # physical audio format.
        bclk   "master"                 # Platform is master of bit clock
        fsync  "slave"                  # Platform is slave of fsync
   }
   

Physical DAI

A physical DAI (e.g. backend DAI for DPCM) is defined as a new section that can include a unique ID, playback and capture stream capabilities, optional flags, and private data.
Its PCM stream capablities are same as those for PCM objects, please refer to section 'PCM Capabilities'.
   SectionDAI."name" {
        index "1"                       # Index number
        id "0"                          # used for binding to the Backend DAI
        pcm."playback" {
                capabilities "capabilities1"    # capabilities for playback
        }
        pcm."capture" {
                capabilities "capabilities2"    # capabilities for capture
        }
        symmetric_rates "true"                  # optional flags
        symmetric_channels "true"
        symmetric_sample_bits "false"
        data "name"                     # optional private data
   }
   

Manifest Private Data

Manfiest may have private data. Users need to define a manifest section and add the references to 1 or multiple data sections. Please refer to section 'How to define an element with private data'.
And the text conf file can have at most 1 manifest section.

Manifest section is defined as follows :-
   SectionManifest"name" {
        data "name"                     # optional private data
   }
   

Include other files

Users may include other files in a text conf file via alsaconf syntax <path/to/configuration-file>. This allows users to define common info in separate files (e.g. vendor tokens, tuples) and share them for different platforms, thus save the total size of config files.
Users can also specifiy additional configuraiton directories relative to "/usr/share/alsa/" to search the included files, via alsaconf syntax <searchfdir:/relative-path/to/usr/share/alsa>.

For example, file A and file B are two text conf files for platform X, they will be installed to /usr/share/alsa/topology/platformx. If we need file A to include file B, in file A we can add:
<searchdir:topology/platformx>
<name-of-file-B>

ALSA conf will search and open an included file in the following order of priority:

  1. directly open the file by its name;
  2. search for the file name in "/usr/share/alsa";
  3. search for the file name in user specified subdirectories under "/usr/share/alsa".
The order of the included files need not to be same as their dependencies, since the topology library will load them all before parsing their dependencies.
The configuration directories defined by a file will only be used to search the files included by this file.

Macro Definition Documentation

#define SND_TPLG_INDEX_ALL   0

Fit for all user cases

#define SND_TPLG_MAX_CHAN   8

Maximum number of channels supported in one control


Typedef Documentation

typedef struct snd_tplg snd_tplg_t

Topology context


Enumeration Type Documentation

Topology object types

Enumerator:
SND_TPLG_TYPE_TLV 

TLV Data

SND_TPLG_TYPE_MIXER 

Mixer control

SND_TPLG_TYPE_ENUM 

Enumerated control

SND_TPLG_TYPE_TEXT 

Text data

SND_TPLG_TYPE_DATA 

Private data

SND_TPLG_TYPE_BYTES 

Byte control

SND_TPLG_TYPE_STREAM_CONFIG 

PCM Stream configuration

SND_TPLG_TYPE_STREAM_CAPS 

PCM Stream capabilities

SND_TPLG_TYPE_PCM 

PCM stream device

SND_TPLG_TYPE_DAPM_WIDGET 

DAPM widget

SND_TPLG_TYPE_DAPM_GRAPH 

DAPM graph elements

SND_TPLG_TYPE_BE 

BE DAI link

SND_TPLG_TYPE_CC 

Hostless codec <-> codec link

SND_TPLG_TYPE_MANIFEST 

Topology manifest

SND_TPLG_TYPE_TOKEN 

Vendor tokens

SND_TPLG_TYPE_TUPLE 

Vendor tuples

SND_TPLG_TYPE_LINK 

Physical DAI link

SND_TPLG_TYPE_HW_CONFIG 

Link HW config

SND_TPLG_TYPE_DAI 

Physical DAI


Function Documentation

int snd_tplg_add_object ( snd_tplg_t tplg,
snd_tplg_obj_template_t t 
)

Register topology template object.

Parameters:
tplgTopology instance.
tTemplate object.
Returns:
Zero on success, otherwise a negative error code
int snd_tplg_build ( snd_tplg_t tplg,
const char *  outfile 
)

Build all registered topology data into binary file.

Parameters:
tplgTopology instance.
outfileBinary topology output file.
Returns:
Zero on success, otherwise a negative error code
int snd_tplg_build_file ( snd_tplg_t tplg,
const char *  infile,
const char *  outfile 
)

Parse and build topology text file into binary file.

Parameters:
tplgTopology instance.
infileTopology text input file to be parsed
outfileBinary topology output file.
Returns:
Zero on success, otherwise a negative error code
void snd_tplg_free ( snd_tplg_t tplg)

Free a topology parser instance.

Parameters:
tplgTopology parser instance
snd_tplg_t* snd_tplg_new ( void  )

Create a new topology parser instance.

Returns:
New topology parser instance
int snd_tplg_set_manifest_data ( snd_tplg_t tplg,
const void *  data,
int  len 
)

Attach private data to topology manifest.

Parameters:
tplgTopology instance.
dataPrivate data.
lenLength of data in bytes.
Returns:
Zero on success, otherwise a negative error code
int snd_tplg_set_version ( snd_tplg_t tplg,
unsigned int  version 
)

Set an optional vendor specific version number.

Parameters:
tplgTopology instance.
versionVendor specific version number.
Returns:
Zero on success, otherwise a negative error code
void snd_tplg_verbose ( snd_tplg_t tplg,
int  verbose 
)

Enable verbose reporting of binary file output.

Parameters:
tplgTopology Instance
verboseEnable verbose output level if non zero