diff options
Diffstat (limited to 'include/uapi/sound/firewire.h')
-rw-r--r-- | include/uapi/sound/firewire.h | 35 |
1 files changed, 35 insertions, 0 deletions
diff --git a/include/uapi/sound/firewire.h b/include/uapi/sound/firewire.h index ae12826ed641..347fd7a05596 100644 --- a/include/uapi/sound/firewire.h +++ b/include/uapi/sound/firewire.h @@ -108,4 +108,39 @@ struct snd_firewire_tascam_state { __be32 data[SNDRV_FIREWIRE_TASCAM_STATE_COUNT]; }; +// In below MOTU models, software is allowed to control their DSP by accessing to registers. +// - 828mk2 +// - 896hd +// - Traveler +// - 8 pre +// - Ultralite +// - 4 pre +// - Audio Express +// +// On the other hand, the status of DSP is split into specific messages included in the sequence of +// isochronous packet. ALSA firewire-motu driver gathers the messages and allow userspace applications +// to read it via ioctl. In 828mk2, 896hd, and Traveler, hardware meter for all of physical inputs +// are put into the message, while one pair of physical outputs is selected. The selection is done by +// LSB one byte in asynchronous write quadlet transaction to 0x'ffff'f000'0b2c. +// +// I note that V3HD/V4HD uses asynchronous transaction for the purpose. The destination address is +// registered to 0x'ffff'f000'0b38 and '0b3c by asynchronous write quadlet request. The size of +// message differs between 23 and 51 quadlets. For the case, the number of mixer bus can be extended +// up to 12. + +#define SNDRV_FIREWIRE_MOTU_REGISTER_DSP_METER_COUNT 40 + +/** + * struct snd_firewire_motu_register_dsp_meter - the container for meter information in DSP + * controlled by register access + * @data: Signal level meters. The mapping between position and input/output channel is + * model-dependent. + * + * The structure expresses the part of DSP status for hardware meter. The u8 storage includes linear + * value for audio signal level between 0x00 and 0x7f. + */ +struct snd_firewire_motu_register_dsp_meter { + __u8 data[SNDRV_FIREWIRE_MOTU_REGISTER_DSP_METER_COUNT]; +}; + #endif /* _UAPI_SOUND_FIREWIRE_H_INCLUDED */ |