Commit 74c5b31c authored by Mike Waychison's avatar Mike Waychison Committed by Greg Kroah-Hartman
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driver: Google EFI SMI 



The "gsmi" driver bridges userland with firmware specific routines for
accessing hardware.

Currently, this driver only supports NVRAM and eventlog information.
Deprecated functions have been removed from the driver, though their
op-codes are left in place so that they are not re-used.

This driver works by trampolining into the firmware via the smi_command
outlined in the FADT table.  Three protocols are used due to various
limitations over time, but all are included herein.

This driver should only ever load on Google boards, identified by either
a "Google, Inc." board vendor string in DMI, or "GOOGLE" in the OEM
strings of the FADT ACPI table.  This logic happens in
gsmi_system_valid().

Signed-off-by: default avatarDuncan Laurie <dlaurie@google.com>
Signed-off-by: default avatarAaron Durbin <adurbin@google.com>
Signed-off-by: default avatarMike Waychison <mikew@google.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent f548ccd4

Documentation/ABI/testing/sysfs-firmware-gsmi

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What:		/sys/firmware/gsmi

Date:		March 2011

Contact:	Mike Waychison <mikew@google.com>

Description:

		Some servers used internally at Google have firmware

		that provides callback functionality via explicit SMI

		triggers.  Some of the callbacks are similar to those

		provided by the EFI runtime services page, but due to

		historical reasons this different entry-point has been

		used.



		The gsmi driver implements the kernel's abstraction for

		these firmware callbacks.  Currently, this functionality

		is limited to handling the system event log and getting

		access to EFI-style variables stored in nvram.



		Layout:



		/sys/firmware/gsmi/vars:



			This directory has the same layout (and

			underlying implementation as /sys/firmware/efi/vars.

			See Documentation/ABI/*/sysfs-firmware-efi-vars

			for more information on how to interact with

			this structure.



		/sys/firmware/gsmi/append_to_eventlog - write-only:



			This file takes a binary blob and passes it onto

			the firmware to be timestamped and appended to

			the system eventlog.  The binary format is

			interpreted by the firmware and may change from

			platform to platform.  The only kernel-enforced

			requirement is that the blob be prefixed with a

			32bit host-endian type used as part of the

			firmware call.



		/sys/firmware/gsmi/clear_config - write-only:



			Writing any value to this file will cause the

			entire firmware configuration to be reset to

			"factory defaults".  Callers should assume that

			a reboot is required for the configuration to be

			cleared.



		/sys/firmware/gsmi/clear_eventlog - write-only:



			This file is used to clear out a portion/the

			whole of the system event log.  Values written

			should be values between 1 and 100 inclusive (in

			ASCII) representing the fraction of the log to

			clear.  Not all platforms support fractional

			clearing though, and this writes to this file

			will error out if the firmware doesn't like your

			submitted fraction.



			Callers should assume that a reboot is needed

			for this operation to complete.

drivers/firmware/Kconfig

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@@ -157,4 +157,6 @@ config SIGMA 
	  If unsure, say N here.  Drivers that need these helpers will select

	  this option automatically.



source "drivers/firmware/google/Kconfig"



endmenu

drivers/firmware/Makefile

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@@ -13,3 +13,5 @@ obj-$(CONFIG_ISCSI_IBFT_FIND) += iscsi_ibft_find.o 
obj-$(CONFIG_ISCSI_IBFT)	+= iscsi_ibft.o

obj-$(CONFIG_FIRMWARE_MEMMAP)	+= memmap.o

obj-$(CONFIG_SIGMA)		+= sigma.o



obj-y  += google/

drivers/firmware/google/Kconfig

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config GOOGLE_SMI

	tristate "SMI interface for Google platforms"

	depends on ACPI && DMI

	select EFI_VARS

	help

	  Say Y here if you want to enable SMI callbacks for Google

	  platforms.  This provides an interface for writing to and

	  clearing the EFI event log and reading and writing NVRAM

	  variables.

drivers/firmware/google/Makefile

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obj-$(CONFIG_GOOGLE_SMI)		+= gsmi.o

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