On Tue, Feb 01, 2011 at 07:17:41PM +0530, Anirudh Ghayal wrote:

One-touch headset controller is a hardware module in Qualcomm's PMIC8058.
It supports headset insert/remove and switch press/release detection events
over 3 MIC BIAS lines. The MIC BIAS lines can be configured to support
headset detection or act as regular BIAS lines.

This should probably be integrated with ASoC for management of the
biases if nothing else, though it'd also allow other stuff.  ALSA has
support for creating input devices from jacks already.

+	input_set_capability(ipd, EV_SW, SW_HEADPHONE_INSERT);
+	input_set_capability(ipd, EV_KEY, KEY_MEDIA);

The ALSA (well, ASoC) stuff would also allow the input device to be
merged with that for other detection methods so if you've got a headset
jack capable of detecting other things (eg, mechanical insertion or
separate mic and headphone detection).