mb/asus/p5qc: Add ASUS P5Q as a variant (with documentation)

Change-Id: I6c7bbb89af88cce1a53c21a4b4d8bc1c284e1cb2
Signed-off-by: Ivan Vatlin <jenrus@tuta.io>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/38143
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>

Documentation/mainboard/asus/p5q.md

@@ -0,0 +1,77 @@
+# ASUS P5Q
+
+This page describes how to run coreboot on the [ASUS P5Q] desktop board.
+
+## TODO
+
+The following things are working in this coreboot port:
+
++ PCI slots
++ PCI-e slots
++ Onboard Ethernet
++ USB
++ Onboard sound card
++ PS/2 keyboard
++ All 4 DIMM slots
++ S3 suspend and resume
++ Red SATA ports
+
+The following things are still missing from this coreboot port:
+
++ PS/2 mouse support
++ PATA aka IDE (because of buggy IDE controller)
++ Fan control (will be working on 100% power)
++ TPM module (support not implemented)
+
+The following things are untested on this coreboot port:
+
++ S/PDIF
++ CD Audio In
++ Floppy disk drive
++ FireWire: PCI device shows up and driver loads, no further test
+
+
+## Flashing coreboot
+
+```eval_rst
++-------------------+----------------+
+| Type              | Value          |
++===================+================+
+| Socketed flash    | Yes            |
++-------------------+----------------+
+| Model             | MX25L8005      |
++-------------------+----------------+
+| Size              | 1 MiB          |
++-------------------+----------------+
+| Package           | Socketed DIP-8 |
++-------------------+----------------+
+| Write protection  | No             |
++-------------------+----------------+
+| Dual BIOS feature | No             |
++-------------------+----------------+
+| Internal flashing | Yes            |
++-------------------+----------------+
+```
+
+You can flash coreboot into your motherboard using [this guide].
+
+## Technology
+
+```eval_rst
++------------------+---------------------------------------------------+
+| Northbridge      | Intel P45 (called x4x in coreboot code)           |
++------------------+---------------------------------------------------+
+| Southbridge      | Intel ICH10R (called i82801jx in coreboot code)   |
++------------------+---------------------------------------------------+
+| CPU (LGA775)     | Model f4x, f6x, 6fx, 1067x (Pentium 4, d, Core 2) |
++------------------+---------------------------------------------------+
+| SuperIO          | Winbond W83667HG                                  |
++------------------+---------------------------------------------------+
+| Coprocessor      | No                                                |
++------------------+---------------------------------------------------+
+| Clockgen (CK505) | ICS 9LPRS918JKLF                                  |
++------------------+---------------------------------------------------+
+```
+
+[ASUS P5Q]: https://www.asus.com/Motherboards/P5Q
+[this guide]: https://doc.coreboot.org/flash_tutorial/int_flashrom.html