the following patch was just integrated into master: commit db4ce0735688cb695465e162974d88f95e8a4833 Author: Gabe Black gabeblack@google.com Date: Thu Mar 29 18:04:56 2012 -0700
Set up ChromeOS dev mode, recovery, and write protect GPIOs on Emerald Lake 2.
The Emerald Lake 2 CRB wasn't designed with ChromeOS in mind, so there aren't any actual developer mode, recovery mode, or write protect switches, let alone GPIOs to read them from. Instead, I've commandeered signals connected to GPIOs which are for other things but which aren't used by hardware or, for instance, the EC to do something Coreboot doesn't control.
The recovery mode switch is connected to GPIO 22 and is called BIOS_REC on the schematic. The name is at least very reminiscent of the right thing even if it's supposed to be used for something else. There's a jumper on the board labelled J8G1 which can force the line to ground, and if not, there's a switch on the front of the case which toggles its value. "RECOVER" is for recovery mode and "KEEP" is for normal mode.
The developer mode switch is connected to GPIO 57 and is called SV_DET on the schematic. It's connected to a jumper labelled J8E2 on the board and, as far as I can tell, can't be controlled in any other way. When the jumper is in place and the pins are shorted, developer mode is selected. When the jumper is removed, normal mode is selected.
The write protect is connected to GPIO 48 which is called BIOS_RESP on the schematic. It's connected to a jumper labelled J8E3 which, like j8E2, seems to be the only way to control the line it's on. When the jumper is in place, write protect is "disabled", and when it's in place it's "enabled" even though there's no functional difference.
The input for the recovery mode switch was chosen because of the name it already had on the CRB, BIOS recovery, and because there's a switch to control it on the front of the case which makes it easy to get at. The jumpers for developer mode and recovery mode were chosen because there weren't very many options available, and of those these were next to each other which should make them easier to find and work with. It might be a good idea to wire toggle switches up to the pins of those jumpers so they'll be easy to identify, can be labelled, and would be easier to work with than little jumpers in the middle of the motherboard.
Change-Id: Ib2c3dc05077dacfbede596dae143ed81a99dbebd Signed-off-by: Gabe Black gabeblack@google.com
Build-Tested: build bot (Jenkins) at Tue May 1 03:15:02 2012, giving +1 See http://review.coreboot.org/965 for details.
-gerrit