| # SPDX-License-Identifier: GPL-2.0+ |
| # |
| # Copyright 2018 Google LLC |
| # |
| |
| config CROS_FLAG |
| bool "Chromium OS verified boot flags" |
| depends on DM |
| help |
| Chromium OS includes a number of features which are controlled by |
| hardware such as GPIOs or TPM settings. This uclass implements a |
| way of reading these 'vboot' flags, with the each driver advertising |
| the flags it can read and a method for reading those flags. |
| |
| Flags are normally read using vboot_flag_read_walk(). This checks each |
| driver to find the one that implements the requested flag. |
| |
| Typically the flag values do not change value over the course of a |
| boot, but this is not always true. For example, VBOOT_FLAG_LID_OPEN |
| is 1 when the lid is open on a clamshell device, and 0 if the lid is |
| closed. In this case vboot_flag_read_walk_prev() can be used to read |
| the current value of the flag, along with the previous value. This |
| allows transitions to be detected. |
| |
| config CROS_FLAG_GPIO |
| bool "Flags controlled by a GPIO" |
| depends on CROS_FLAG |
| help |
| Enable support for a Chromium OS flag which is controlled by a GPIO. |
| The flag is 1 if the GPIO is high and 0 if the GPIO is low. |
| |
| For sandbox only, the initial value of the flag can be provided in |
| the device tree, for testing purposes. |
| |
| config CROS_FLAG_CONST |
| bool "Flags controlled by a constant" |
| depends on CROS_FLAG |
| help |
| Enable support for a Chromium OS flag which is always the same value, |
| as specified by the device-tree node. The value does not change at |
| all over the life of the verified boot session. This can be useful |
| for flags which are not supported on a particular platform. |
| |
| config CROS_FLAG_CROS_EC |
| bool "Flags controlled by Chromium OS EC" |
| depends on CROS_FLAG |
| help |
| Enable support for a Chromium OS flag which is provided by the EC. |
| This typically involves sending a message to the EC to read the |
| flag. An example might be reading recovery mode, since the EC is |
| able to check the keyboard on start-up for that key combination. |
| |
| config CROS_FLAG_KEY |
| bool "Flags controlled by a keypress" |
| depends on CROS_FLAG && SANDBOX |
| help |
| Enable support for a Chromium OS flag which is controlled by a |
| keypress captured early during start-up. This is only provided for |
| use with sandbox. A short delay at start-up allows capturing the |
| keys to be read by this driver - see cros_ec_check_keyboard(). |
| |
| config CROS_FLAG_SYSINFO |
| bool "Flags controlled by coreboot sysinfo" |
| depends on CROS_FLAG && X86 |
| help |
| Enable support for a Chromium OS flag which is controlled by |
| information received by coreboot in its 'sysinfo' structure. This is |
| used when coreboot is the first bootloader and it chain-loads into |
| U-Boot. Since many of the flags can only be read very early in boot, |
| this provides a way to keep a consistent flag value throughout the |
| boot. |
