I can find the hardware documentation for both Raspberry Pi 1's and Raspberry Pi 2's SoC on the Documentation - Hardware site from raspberrypi.org (Broadcom BCM2835 and Broadcom BCM2836).
However, I couldn't find any documentation for the Raspberry Pi 3 Model B's SoC (Broadcom BCM2837), which I purchased recently.
Is there any similar document what you can recommend for Raspberry Pi 3?
Depending on what you want to accomplish with the documentation, you might find your answers in a few different places.
I found this general discussion quite helpful:
And for the CPU itself:
http://www.arm.com/products/processors/cortex-a/cortex-a53-processor.php
And for the VideoCore, this:
https://docs.broadcom.com/docs-and-downloads/docs/support/videocore/VideoCoreIV-AG100-R.pdf
I've found a BCM2837 datasheet linked from Stanford's CS 140e class. It does correctly map the peripherals to address 0x3Fnnnnnnn, unlike 0x20nnnnnn for the BCM2835.
It's at https://web.stanford.edu/class/cs140e/docs/BCM2837-ARM-Peripherals.pdf
This is the description on the class web page:
Our modified version of the BCM2835 documentation with fixes for the BCM2837 and known errata.
The documentation also contains a section for the RPI 3 specifically: https://www.raspberrypi.org/documentation/hardware/raspberrypi/bcm2837/README.md which says:
This is the Broadcom chip used in the Raspberry Pi 3, and in later models of the Raspberry Pi 2. The underlying architecture of the BCM2837 is identical to the BCM2836.
So you can look up the docs for the Pi 2 on a sibling page https://www.raspberrypi.org/documentation/hardware/raspberrypi/bcm2836/README.md which say:
The underlying architecture in BCM2836 is identical to BCM2835.
which is at: https://www.raspberrypi.org/documentation/hardware/raspberrypi/bcm2835/README.md
So I guess you can somewhat trust in the PDFs for the Pi 1 and Pi 2 pages:
The BMC2837 PDF is also available on the raspberrypi github: https://github.com/raspberrypi/documentation/files/1888662/BCM2837-ARM-Peripherals.-.Revised.-.V2-1.pdf
It seems that BCM2837 shares MIPI interface with camera module, thus distributing the 4 lanes to 2 lane MIPI for DSI and another two for camera support. That's why resolution of display is only 800x600 pixel. If You can use a chip like ICN6202, You can probably convert existing 2 lanes to LVDS and have a third party LCD, but abandoning the camera and using 4 lane MIPI to LVDS would mean to setting the broadcomm chip, without documentation impossible.
