platform/x86: think-lmi: Add WMI interface support on Lenovo platforms

For Lenovo platforms that support a WMI interface to the BIOS add
support, using the firmware-attributes class, to allow users to access
and modify various BIOS related settings.
Signed-off-by: Mark Pearson <markpearson@lenovo.com>
Link: https://lore.kernel.org/r/20210530223111.25929-3-markpearson@lenovo.comReviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

Documentation/ABI/testing/sysfs-class-firmware-attributes

@@ -197,8 +197,24 @@ Description:
 		Drivers may emit a CHANGE uevent when a password is set or unset
 		userspace may check it again.
 
-		On Dell systems, if Admin password is set, then all BIOS attributes
+		On Dell and Lenovo systems, if Admin password is set, then all BIOS attributes
 		require password validation.
+		On Lenovo systems if you change the Admin password the new password is not active until
+		the next boot.
+
+		Lenovo specific class extensions
+		------------------------------
+
+		On Lenovo systems the following additional settings are available:
+
+		lenovo_encoding:
+					The encoding method that is used. This can be either "ascii"
+					or "scancode". Default is set to "ascii"
+
+		lenovo_kbdlang:
+					The keyboard language method that is used. This is generally a
+					two char code (e.g. "us", "fr", "gr") and may vary per platform.
+					Default is set to "us"
 
 What:		/sys/class/firmware-attributes/*/attributes/pending_reboot
 Date:		February 2021

MAINTAINERS

@@ -18163,6 +18163,13 @@ W:	http://thinkwiki.org/wiki/Ibm-acpi
 T:	git git://repo.or.cz/linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git
 F:	drivers/platform/x86/thinkpad_acpi.c
 
+THINKPAD LMI DRIVER
+M:	Mark Pearson <markpearson@lenovo.com>
+L:	platform-driver-x86@vger.kernel.org
+S:	Maintained
+F:	Documentation/ABI/testing/sysfs-class-firmware-attributes
+F:	drivers/platform/x86/think-lmi.?
+
 THUNDERBOLT DMA TRAFFIC TEST DRIVER
 M:	Isaac Hazan <isaac.hazan@intel.com>
 L:	linux-usb@vger.kernel.org

drivers/platform/x86/Kconfig

@@ -640,6 +640,17 @@ config THINKPAD_ACPI_HOTKEY_POLL
 	  If you are not sure, say Y here.  The driver enables polling only if
 	  it is strictly necessary to do so.
 
+config THINKPAD_LMI
+	tristate "Lenovo WMI-based systems management driver"
+	depends on ACPI_WMI
+	select FW_ATTR_CLASS
+	help
+	  This driver allows changing BIOS settings on Lenovo machines whose
+	  BIOS support the WMI interface.
+
+	  To compile this driver as a module, choose M here: the module will
+	  be called think-lmi.
+
 config INTEL_ATOMISP2_LED
 	tristate "Intel AtomISP2 camera LED driver"
 	depends on GPIOLIB && LEDS_GPIO

drivers/platform/x86/Makefile

@@ -63,6 +63,7 @@ obj-$(CONFIG_IBM_RTL)		+= ibm_rtl.o
 obj-$(CONFIG_IDEAPAD_LAPTOP)	+= ideapad-laptop.o
 obj-$(CONFIG_SENSORS_HDAPS)	+= hdaps.o
 obj-$(CONFIG_THINKPAD_ACPI)	+= thinkpad_acpi.o
+obj-$(CONFIG_THINKPAD_LMI)	+= think-lmi.o
 
 # Intel
 obj-$(CONFIG_INTEL_ATOMISP2_LED)	+= intel_atomisp2_led.o

drivers/platform/x86/think-lmi.h

+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#ifndef _THINK_LMI_H_
+#define _THINK_LMI_H_
+
+#include <linux/types.h>
+
+#define TLMI_SETTINGS_COUNT  256
+#define TLMI_SETTINGS_MAXLEN 512
+#define TLMI_PWD_BUFSIZE     129
+#define TLMI_PWDTYPE_MAXLEN   64
+#define TLMI_ENC_MAXLEN       64
+#define TLMI_LANG_MAXLEN       4
+#define TLMI_PWDTYPE_LEN       4
+/*
+ * Longest string should be in the set command: allow size of BIOS
+ * option and choice
+ */
+#define TLMI_GETSET_MAXLEN (TLMI_SETTINGS_MAXLEN + TLMI_SETTINGS_MAXLEN)
+
+/* Possible error values */
+struct tlmi_err_codes {
+	const char *err_str;
+	int err_code;
+};
+
+enum encoding_option {
+	TLMI_ENCODING_ASCII,
+	TLMI_ENCODING_SCANCODE,
+};
+
+/* password configuration details */
+struct tlmi_pwdcfg {
+	uint32_t password_mode;
+	uint32_t password_state;
+	uint32_t min_length;
+	uint32_t max_length;
+	uint32_t supported_encodings;
+	uint32_t supported_keyboard;
+};
+
+/* password setting details */
+struct tlmi_pwd_setting {
+	struct kobject kobj;
+	bool valid;
+	char display_name[TLMI_PWDTYPE_MAXLEN];
+	char password[TLMI_PWD_BUFSIZE];
+	const char *pwd_type;
+	const char *role;
+	int minlen;
+	int maxlen;
+	enum encoding_option encoding;
+	char kbdlang[TLMI_LANG_MAXLEN];
+};
+
+/* Attribute setting details */
+struct tlmi_attr_setting {
+	struct kobject kobj;
+	int index;
+	char display_name[TLMI_SETTINGS_MAXLEN];
+	char *possible_values;
+};
+
+struct think_lmi {
+	struct wmi_device *wmi_device;
+
+	int settings_count;
+	bool can_set_bios_settings;
+	bool can_get_bios_selections;
+	bool can_set_bios_password;
+	bool can_get_password_settings;
+
+	struct tlmi_attr_setting *setting[TLMI_SETTINGS_COUNT];
+	struct device *class_dev;
+	struct kset *attribute_kset;
+	struct kset *authentication_kset;
+	struct tlmi_pwd_setting *pwd_admin;
+	struct tlmi_pwd_setting *pwd_power;
+};
+
+#endif /* !_THINK_LMI_H_ */