BIOS Version

You can check the current BIOS and ECP versions on your ThinkPad by using dmidecode. For example:

# dmidecode -s bios-version

6DET52WW (3.02 )

# dmidecode -t 11

# dmidecode 3.1
Getting SMBIOS data from sysfs.
SMBIOS 2.4 present.

Handle 0x001D, DMI type 11, 5 bytes
OEM Strings
	String 1: IBM ThinkPad Embedded Controller -[7XHT22WW-1.04    ]-

Showing BIOS version 3.02 (6DET52WW) and ECP version 1.04 (7XHT22WW).

Alternatively you can grep the information from dmesg

$ dmesg | grep "ThinkPad BIOS"

[    3.758331] thinkpad_acpi: ThinkPad BIOS 6DET52WW (3.02 ), EC 7XHT22WW-1.04