Documentation: Add Asus P2B-LS

Change-Id: Ib885c4dd8472ed2b0a61c548f6ef652979a33153
Signed-off-by: Keith Hui <buurin@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/61537
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>

1 files changed, 108 insertions, 0 deletions

diff --git a/Documentation/mainboard/asus/p2b-ls.md b/Documentation/mainboard/asus/p2b-ls.md
new file mode 100644
index 0000000000..bdb6d7df4f
--- /dev/null
+++ b/Documentation/mainboard/asus/p2b-ls.md
@@ -0,0 +1,108 @@
+# ASUS P2B-LS
+
+This page describes how to run coreboot on the ASUS P2B-LS mainboard.
+
+## Variants
+
+- P2B-LS
+- P2B-L (Same circuit board with SCSI components omitted)
+- P2B-S (Same circuit board with ethernet components omitted)
+
+## Flashing coreboot
+
+```eval_rst
++---------------------+---------------------------+
+| Type                | Value                     |
++=====================+===========================+
+| Model               | SST 39SF020A (or similar) |
++---------------------+---------------------------+
+| Protocol            | Parallel                  |
++---------------------+---------------------------+
+| Size                | 256 KiB                   |
++---------------------+---------------------------+
+| Package             | DIP-32                    |
++---------------------+---------------------------+
+| Socketed            | yes                       |
++---------------------+---------------------------+
+| Write protection    | no                        |
++---------------------+---------------------------+
+| Dual BIOS feature   | no                        |
++---------------------+---------------------------+
+| Internal flashing   | yes                       |
++---------------------+---------------------------+
+```
+
+[flashrom] works out of the box since 0.9.2.
+Because of deficiency in vendor firmware, user needs to override the laptop
+warning as prompted. Once coreboot is in place there will be no further issue.
+
+### CPU microcode considerations
+
+By default, this board includes microcode updates for 5 families of Intel CPUs
+because of the wide variety of CPUs the board supports, directly or with an
+adapter. These take up a third of the total flash space leaving only 20kB free
+in the final cbfs image. It may be necessary to build a custom microcode update
+file by manually concatenating files in 3rdparty/intel-microcode/intel-ucode
+for only CPU models that the board will actually be run with.
+
+## Working
+
+- Slot 1 and Socket 370 CPUs and their L1/L2 caches
+- PS/2 keyboard with SeaBIOS (See [Known issues])
+- IDE hard drives
+- Ethernet (-LS, -L; Intel 82558)
+- SCSI (-LS, -S; Adaptec AIC7890)
+- USB
+- ISA add-on cards
+- PCI add-on cards
+- AGP graphics card
+- Floppy
+- Serial ports 1 and 2
+- Reboot
+- Soft off
+
+## Known issues
+
+- PS/2 keyboard may not be usable until Linux has completely booted.
+  With SeaBIOS as payload, setting keyboard initialization timeout to
+  500ms may fix the issue.
+
+- i440BX does not support 256Mbit RAM modules. If installed, coreboot
+  will attempt to initialize them at half their capacity anyway
+  whereas vendor firmware will not boot at all.
+
+- ECC memory can be used, but ECC support is still pending.
+
+- Termination is enabled for all SCSI ports (if equipped). Support to
+  disable termination is pending. Note that the SCSI-68 port is
+  always terminated, even with vendor firmware.
+
+## Untested
+
+- Parallel port
+- EDO memory
+- Infrared
+- PC speaker
+
+## Not working
+
+- S3 suspend to RAM
+
+## Technology
+
+```eval_rst
++------------------+--------------------------------------------------+
+| Northbridge      | :doc:`../../northbridge/intel/i440bx/index`      |
++------------------+--------------------------------------------------+
+| Southbridge      | i82371eb                                         |
++------------------+--------------------------------------------------+
+| CPU              | P6 family for Slot 1 and Socket 370              |
+|                  | (all models from model_63x to model_6bx)         |
++------------------+--------------------------------------------------+
+| Super I/O        | winbond/w83977tf                                 |
++------------------+--------------------------------------------------+
+```
+
+## Extra resources
+
+[flashrom]: https://flashrom.org/Flashrom