platform/chrome: Add ChromeOS ACPI device driver

The x86 Chromebooks have the ChromeOS ACPI device. This driver attaches
to the ChromeOS ACPI device and exports the values reported by ACPI in a
sysfs directory. This data isn't present in ACPI tables when read
through ACPI tools, hence a driver is needed to do it. The driver gets
data from firmware using the ACPI component of the kernel. The ACPI values
are presented in string form (numbers as decimal values) or binary
blobs, and can be accessed as the contents of the appropriate read only
files in the standard ACPI device's sysfs directory tree. This data is
consumed by the ChromeOS user space.

Reviewed-by: Guenter Roeck <groeck@chromium.org>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Co-developed-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
Signed-off-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
Signed-off-by: Tzung-Bi Shih <tzungbi@kernel.org>
Link: https://lore.kernel.org/r/Yn4OKYrtV35Dv+nd@debian-BULLSEYE-live-builder-AMD64

1 files changed, 126 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/sysfs-driver-chromeos-acpi b/Documentation/ABI/testing/sysfs-driver-chromeos-acpi
new file mode 100644
index 000000000000..5b59ef9d7b37
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-driver-chromeos-acpi
@@ -0,0 +1,126 @@
+What:		/sys/bus/platform/devices/GGL0001:*/BINF.2
+Date:		May 2022
+KernelVersion:	5.19
+Description:
+		This file shows information about the current boot of
+		the active EC firmware.
+		  * 0 - Read only (recovery) firmware.
+		  * 1 - Rewritable firmware.
+
+What:		/sys/bus/platform/devices/GGL0001:*/BINF.3
+Date:		May 2022
+KernelVersion:	5.19
+Description:
+		This file shows information about the current boot of
+		the active main	firmware type.
+		  * 0 - Recovery.
+		  * 1 - Normal.
+		  * 2 - Developer.
+		  * 3 - Netboot (factory installation only).
+
+What:		/sys/bus/platform/devices/GGL0001:*/CHSW
+Date:		May 2022
+KernelVersion:	5.19
+Description:
+		This file shows the switch position for the Chrome OS specific
+		hardware switches.
+		  * 0   - No changes.
+		  * 2   - Recovery button was pressed when firmware booted.
+		  * 4   - Recovery button was pressed when EC firmware booted.
+		  * 32  - Developer switch was enabled when firmware booted.
+		  * 512 - Firmware write protection was disabled when firmware
+			  booted.
+
+What:		/sys/bus/platform/devices/GGL0001:*/FMAP
+Date:		May 2022
+KernelVersion:	5.19
+Description:
+		This file shows the physical memory address of the start of
+		the main processor firmware flashmap.
+
+What:		/sys/bus/platform/devices/GGL0001:*/FRID
+Date:		May 2022
+KernelVersion:	5.19
+Description:
+		This file shows the firmware version for the read-only portion
+		of the main processor firmware.
+
+What:		/sys/bus/platform/devices/GGL0001:*/FWID
+Date:		May 2022
+KernelVersion:	5.19
+Description:
+		This file shows the firmware version for the rewritable portion
+		of the main processor firmware.
+
+What:		/sys/bus/platform/devices/GGL0001:*/GPIO.X/GPIO.0
+Date:		May 2022
+KernelVersion:	5.19
+Description:
+		This file shows the type of the GPIO signal for the Chrome OS
+		specific GPIO assignments.
+		  * 1   - Recovery button.
+		  * 2   - Developer mode switch.
+		  * 3   - Firmware write protection switch.
+		  * 256 to 511 - Debug header GPIO 0 to GPIO 255.
+
+What:		/sys/bus/platform/devices/GGL0001:*/GPIO.X/GPIO.1
+Date:		May 2022
+KernelVersion:	5.19
+Description:
+		This file shows the signal attributes of the GPIO signal.
+		  * 0 - Signal is active low.
+		  * 1 - Signal is active high.
+
+What:		/sys/bus/platform/devices/GGL0001:*/GPIO.X/GPIO.2
+Date:		May 2022
+KernelVersion:	5.19
+Description:
+		This file shows the GPIO number on the specified GPIO
+		controller.
+
+What:		/sys/bus/platform/devices/GGL0001:*/GPIO.X/GPIO.3
+Date:		May 2022
+KernelVersion:	5.19
+Description:
+		This file shows the name of the GPIO controller.
+
+What:		/sys/bus/platform/devices/GGL0001:*/HWID
+Date:		May 2022
+KernelVersion:	5.19
+Description:
+		This file shows the hardware ID for the Chromebook.
+
+What:		/sys/bus/platform/devices/GGL0001:*/MECK
+Date:		May 2022
+KernelVersion:	5.19
+Description:
+		This binary file returns the SHA-1 or SHA-256 hash that is
+		read out of the Management Engine extended registers during
+		boot. The hash is exported vi ACPI so the OS can verify that
+		the Management Engine firmware has not changed. If Management
+		Engine is not present, or if the firmware was unable to read the
+		extended registers, this buffer size can be zero.
+
+What:		/sys/bus/platform/devices/GGL0001:*/VBNV.0
+Date:		May 2022
+KernelVersion:	5.19
+Description:
+		This file shows the offset in CMOS bank 0 of the verified boot
+		non-volatile storage block, counting from the first writable
+		CMOS byte (that is, 'offset = 0' is the byte following the 14
+		bytes of clock data).
+
+What:		/sys/bus/platform/devices/GGL0001:*/VBNV.1
+Date:		May 2022
+KernelVersion:	5.19
+Description:
+		This file shows the size in bytes of the verified boot
+		non-volatile storage block.
+
+What:		/sys/bus/platform/devices/GGL0001:*/VDAT
+Date:		May 2022
+KernelVersion:	5.19
+Description:
+		This binary file returns the verified boot data block shared
+		between the firmware verification step and the kernel
+		verification step.