AC'97 Audio driver

[Jan Vesely]

Implement a driver for an audio device compliant with the AC'97 specification pluggable into the HelenOS audio subsystem (Hound).

Details

Although HelenOS has a sound server that can mix output from multiple applications, currently only Sound Blaster 16 and Intel HDA hardware is supported. This former is not practically usable on today's hardware outside of emulators such as QEMU.

The goal of this ticket is to implement a driver for AC'97 class of audio devices that would be pluggable into to the sound subsystem and to the device driver framework implemented in HelenOS. The driver should at least support audio playback on virtual devices emulated in VirtualBox and QEMU and optionally on actual hardware.

AC'97 devices are simpler than Intel HDA devices. This ticket should be considered an easier alternative to ticket #575. The difficulty can be further scaled down by limiting the scope to a specific AC'97 revision.

Gains and Benefits

Although replaced by the newer Intel HDA standard, the AC'97 devices were the de facto standard in previous generations of sound cards for PC. Implementing a driver for sound output output via Intel HD Audio would allow to use HelenOS sound system on real hardware, improving the user experience and overall usefulness of the system from the end-user point of view.

Difficulty

Medium

Required skills

A successful applicant will have good skills of programming in the C language and the ability to survive in a non-standard non-POSIX environment. Previous experience with driver or sound system implementation would be beneficial, as well as the knowledge of I/O device architecture (PCI, MMIO, DMA).

Documentation

• ​Audio Codec ‘97
• ​Intel ® 82801AA (ICH) & Intel ® 82801AB (ICH0) I/O Controller Hub AC ’97

Possible mentors

HelenOS Core Team, Jiri Svoboda

[Jiri Svoboda]

In VirtualBox, ICH 97 is the default audio device in the OS profile Other - Other/Unknown [64-bit]. Therefore supporting this device would simplify use in VirtualBox / increase the chance that somebody would get audio running the first time around.