Introduce support for Systems Management Driver over WMI for Dell Sys…

…tems

The Dell WMI Systems Management Driver provides a sysfs
interface for systems management to enable BIOS configuration
capability on certain Dell Systems.

This driver allows user to configure Dell systems with a
uniform common interface. To facilitate this, the patch
introduces a generic way for driver to be able to create
configurable BIOS Attributes available in Setup (F2) screen.

Cc: Hans de Goede <hdegoede@redhat.com>
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: mark gross <mgross@linux.intel.com>

Co-developed-by: Mario Limonciello <mario.limonciello@dell.com>
Signed-off-by: Mario Limonciello <mario.limonciello@dell.com>
Co-developed-by: Prasanth KSR <prasanth.ksr@dell.com>
Signed-off-by: Prasanth KSR <prasanth.ksr@dell.com>
Signed-off-by: Divya Bharathi <divya_bharathi@dell.com>

Documentation/ABI/testing/sysfs-platform-dell-wmi-sysman

@@ -0,0 +1,175 @@
+What:		/sys/devices/platform/dell-wmi-sysman/attributes/
+Date:		December 2020
+KernelVersion:	5.10
+Contact:	Divya Bharathi <Divya.Bharathi@Dell.com>,
+		Mario Limonciello <mario.limonciello@dell.com>,
+		Prasanth KSR <prasanth.ksr@dell.com>
+Description:
+		The Dell WMI Systems Management Driver provides a sysfs interface
+		for systems management software to enable BIOS configuration
+		capability on certain Dell systems. This directory exposes
+		interfaces for interacting with BIOS attributes.
+
+		Attributes can accept a set of pre-defined valid values (enumeration)
+		or a range of numerical values (integer) or a string.
+
+		current_value:	A file that can be read to obtain the current
+		value of the <attr>
+
+		This file can also be written to in order to update
+		the value of a <attr>
+
+		default_value:	A file that can be read to obtain the default
+		value of the <attr>
+
+		display_name:	A file that can be read to obtain a user friendly
+		description of the at <attr>
+
+		display_name_language_code:	A file that can be read to obtain
+		the IETF language tag corresponding to the "display_name" of the <attr>
+
+		modifier:	A file that can be read to obtain attribute-level
+		dependency rule. It says an attribute X will become read-only or
+		suppressed, if/if-not attribute Y is configured.
+
+		modifier rules can be in following format,
+		[ReadOnlyIf:<attribute>=<value>]
+		[ReadOnlyIfNot:<attribute>=<value>]
+		[SuppressIf:<attribute>=<value>]
+		[SuppressIfNot:<attribute>=<value>]
+
+		For example,
+		AutoOnFri/modifier has value,
+			[SuppressIfNot:AutoOn=SelectDays]
+		This means AutoOnFri will be supressed in BIOS setup if AutoOn
+		attribute is not "SelectDays" and its value will not be effective
+		through sysfs until this rule is met.
+
+		"enumeration"-type specific properties:
+
+		possible_values:	A file that can be read to obtain the possible
+		values of the <attr>. Values are separated using semi-colon.
+
+		value_modifier:	A file that can be read to obtain value-level
+		dependency. This file is similar to modifier but here, an attribute's
+		current value will be forcefully changed based dependent attributes
+		value.
+
+		value_modifier rules can be in following format,
+		<value>[ForceIf:<attribute>=<value>]
+		<value>[ForceIfNot:<attribute>=<value>]
+
+		For example,
+		LegacyOrom/value_modifier has value,
+			Disabled[ForceIf:SecureBoot=Enabled]
+		This means LegacyOrom's current value will be forced to "Disabled"
+		in BIOS setup if SecureBoot is Enabled and its value will not be
+		effective through sysfs until this rule is met.
+
+		"integer"-type specific properties:
+
+		min_value:	A file that can be read to obtain the lower
+		bound value of the <attr>
+
+		max_value:	A file that can be read to obtain the upper
+		bound value of the <attr>
+
+		scalar_increment:	A file that can be read to obtain the
+		resolution of the incremental value this attribute accepts.
+
+		"string"-type specific properties:
+
+		max_length:	A file that can be read to obtain the maximum
+		length value of the <attr>
+
+		min_length:	A file that can be read to obtain the minimum
+		length value of the <attr>
+
+What:		/sys/devices/platform/dell-wmi-sysman/passwords/
+Date:		December 2020
+KernelVersion:	5.10
+Contact:	Divya Bharathi <Divya.Bharathi@Dell.com>,
+		Mario Limonciello <mario.limonciello@dell.com>,
+		Prasanth KSR <prasanth.ksr@dell.com>
+
+		A BIOS Admin password and System Password can be set, reset or
+		cleared using these attributes. An "Admin" password is used for
+		preventing modification to the BIOS settings. A "System" password is
+		required to boot a machine.
+
+		is_password_set:	A file that can be read
+		to obtain flag to see if a password is set on <attr>
+
+		max_password_length:	A file that can be read to obtain the
+		maximum length of the Password
+
+		min_password_length:	A file that can be read to obtain the
+		minimum length of the Password
+
+		current_password: A write only value used for privileged access
+		such as setting attributes when a system or admin password is set
+		or resetting to a new password
+
+		new_password: A write only value that when used in tandem with
+		current_password will reset a system or admin password.
+
+		Note, password management is session specific. If Admin/System
+		password is set, same password must be writen into current_password
+		file (requied for pasword-validation) and must be cleared once the
+		session	is over. For example,
+			echo "password" > current_password
+			echo "disabled" > TouchScreen/current_value
+			echo "" > current_password
+
+
+What:		/sys/devices/platform/dell-wmi-sysman/attributes/reset_bios
+Date:		December 2020
+KernelVersion:	5.10
+Contact:	Divya Bharathi <Divya.Bharathi@Dell.com>,
+		Mario Limonciello <mario.limonciello@dell.com>,
+		Prasanth KSR <prasanth.ksr@dell.com>
+Description:
+		This attribute can be used to reset the BIOS Configuration.
+		Specifically, it tells which type of reset BIOS configuration is being
+		requested on the host.
+
+		Reading from it returns a list of supported options encoded as:
+
+			'builtinsafe' (Built in safe configuration profile)
+			'lastknowngood' (Last known good saved configuration profile)
+			'factory' (Default factory settings configuration profile)
+			'custom' (Custom saved configuration profile)
+
+		The currently selected option is printed in square brackets as
+		shown below:
+
+		# echo "factory" > sys/devices/platform/dell-wmi-sysman/attributes/reset_bios
+
+		# cat sys/devices/platform/dell-wmi-sysman/attributes/reset_bios
+		# builtinsafe lastknowngood [factory] custom
+
+		Note that any changes to this attribute requires a reboot
+		for changes to take effect.
+
+What:		/sys/devices/platform/dell-wmi-sysman/attributes/pending_reboot
+Date:		December 2020
+KernelVersion:	5.10
+Contact:	Divya Bharathi <Divya.Bharathi@Dell.com>,
+		Mario Limonciello <mario.limonciello@dell.com>,
+		Prasanth KSR <prasanth.ksr@dell.com>
+Description:
+		A read-only attribute reads 1 if a reboot is necessary to apply
+		pending BIOS attribute changes.
+
+			0:	All BIOS attributes setting are current
+			1:	A reboot is necessary to get pending BIOS attribute changes
+				applied
+
+
+		Note, userspace applications need to follow below steps for efficient
+		BIOS management,
+		1.	Check if admin password is set. If yes, follow session method for
+			password management as briefed under password section above.
+		2.	Before setting any attribute, check if it has any modifiers
+			or value_modifiers. If yes, incorporate them and then modify
+			attribute.

MAINTAINERS

@@ -4879,6 +4879,15 @@ M:	Mario Limonciello <mario.limonciello@dell.com>
 S:	Maintained
 F:	drivers/platform/x86/dell-wmi-descriptor.c
 
+DELL WMI SYSMAN DRIVER
+M:	Divya Bharathi <divya.bharathi@dell.com>
+M:	Mario Limonciello <mario.limonciello@dell.com>
+M:	Prasanth Ksr <prasanth.ksr@dell.com>
+L:	platform-driver-x86@vger.kernel.org
+S:	Maintained
+F:	drivers/platform/x86/dell-wmi-*-attributes.*
+F:	drivers/platform/x86/dell-wmi-*-interface.c
+
 DELL WMI NOTIFICATIONS DRIVER
 M:	Matthew Garrett <mjg59@srcf.ucam.org>
 M:	Pali Rohár <pali@kernel.org>

drivers/platform/x86/Kconfig

@@ -430,6 +430,18 @@ config DELL_WMI
 	  To compile this driver as a module, choose M here: the module will
 	  be called dell-wmi.
 
+config DELL_WMI_SYSMAN
+	tristate "Dell WMI Systems management WMI driver"
+	depends on ACPI_WMI
+	depends on DMI
+	select NLS
+	help
+	  This driver allows changing BIOS settings on many Dell machines from
+	  2018 and newer without the use of any additional software.
+
+	  To compile this driver as a module, choose M here: the module will
+	  be called dell-wmi-sysman.
+
 config DELL_WMI_DESCRIPTOR
 	tristate
 	depends on ACPI_WMI

drivers/platform/x86/Makefile

@@ -47,6 +47,14 @@ obj-$(CONFIG_DELL_WMI)			+= dell-wmi.o
 obj-$(CONFIG_DELL_WMI_DESCRIPTOR)	+= dell-wmi-descriptor.o
 obj-$(CONFIG_DELL_WMI_AIO)		+= dell-wmi-aio.o
 obj-$(CONFIG_DELL_WMI_LED)		+= dell-wmi-led.o
+obj-$(CONFIG_DELL_WMI_SYSMAN)  += dell-wmi-sysman.o
+dell-wmi-sysman-objs := dell-wmi-sysman-attributes.o \
+				 dell-wmi-enum-attributes.o \
+				 dell-wmi-int-attributes.o \
+				 dell-wmi-string-attributes.o \
+				 dell-wmi-passobj-attributes.o \
+				 dell-wmi-passwordattr-interface.o \
+				 dell-wmi-biosattr-interface.o
 
 # Fujitsu
 obj-$(CONFIG_AMILO_RFKILL)	+= amilo-rfkill.o