If you have a TPM security chip in your system, which
implements the Trusted Computing Group's specification,
say Yes and it will be accessible from within Linux. For
more information see <http://www.trustedcomputinggroup.org>.
An implementation of the Trusted Software Stack (TSS), the
userspace enablement piece of the specification, can be
obtained at: <http://sourceforge.net/projects/trousers>. To
compile this driver as a module, choose M here; the module
will be called tpm. If unsure, say N.
Note: For more TPM drivers enable CONFIG_PNP, CONFIG_ACPI
and CONFIG_PNPACPI.

source code:

drivers/char/tpm/tpm.c