The problem with this is that many data structures have changed. I couldn't get a single one to compile with the ICS SDK. There are many fundamental changes in the way memory is shared for preview/pictures/video, so that will need to be addressed. I have addressed picture only functionality in the skeleton driver, which will show how to transfer a picture back to the HAL.
ICS Camera Driver Overview
The driver seems to be very generic to most Qualcomm SoCs, so either approach should work for many other devices.
See CameraHal_Module.cpp from the ICS source code to see what functions needs to be implemented. It needs to be placed in /system/lib/hw/camera.<target_name_in_build.prop>.so and have the struct "camera_module_t HAL_MODULE_INFO_SYM" inside the code, which the HAL looks for before loading. Once it is loaded, you must implement a few dozen functions to get it to work.
The old drivers primary interface with Android is through libcamera. This loads liboemcamera, which sends commands to the camera kernel driver and the Snapdragon DSP. Liboemcamera is a propriatary library with no documentation apart from the source for QualcommCameraHardware.cpp (which compiles to libcamera.so). The actual Linux kernel module is just a simple I2C bridge to control the camera, and provides no real interface.
Current code/skeleton driver available:
Please do not comment in this thread unless you are able to contribute to the actual development process.