README: drop extra bridge details
Drop extra bridge details from this README as this information is not
kept in the implementation and details that are kept are stored in the
openbmc/docs design.
Signed-off-by: Patrick Venture <venture@google.com>
Change-Id: Ia4c8064e5720efdb7bf6e24d45c95998c10ba995
diff --git a/README.md b/README.md
index 34fa32c..03f0da5 100644
--- a/README.md
+++ b/README.md
@@ -39,45 +39,3 @@
is assumed to be the tarball contents and is written into `/tmp/{tarball_name}.gz`
TODO: Flesh out the UBI approach.
-
-## Bridge Options
-
-### P2A
-
-The PCI-to-AHB bridge is only available on some systems, and provides a 64-KiB
-region that can be pointed anywhere in BMC memory space.
-
-It is controlled by two PCIe MMIO addresses that are based on BAR1. Further
-specifics can be found in the ASPEED data sheet. However, the way it works in
-this instance is that the BMC has configured a region of physical memory it
-plans to use as this buffer region. The BMC returns the address to host program
-so it can configure the PCIe MMIO registers properly for that address.
-
-As an example, a 64-KiB region a platform can use for this
-approach is the last 64-KiB of the VGA reserved region: `0x47ff0000`.
-
-### LPC
-
-Like the P2A mechanism, the BMC must have already allocated a memory region
-with a platform-defined size. This region is mapped to LPC space at the request
-of the host, which also specifies the LPC address and region size in the
-mapping request subcommand. The host can then read the _actual_ LPC address at
-which the BMC was able to map, checking that it's usable.
-
-**Note: Not yet implemented for Stat metadata**
-The command will return 1 byte in the response body with value:
-
-* 0x00 on success (1 byte)
-* 0x16 (EINVAL) if the BMC is not expecting an LPC bridge (1 byte)
-* 0x1B (EFBIG) if the length argument is larger than the BMC can map at the
- requested address, followed by a 32-bit "length" payload representing the
- maximal buffer size that BMC can map. (5 bytes)
-
-After a success map to LPC space, the host can use FlashRequestRegion to read
-the LPC address of the chunk mapped, which should match that requested.
-
-### USB
-
-As future work, USB should be considered an option for staging the image to be
-copied to the BMC.
-