The xpseudo_asm.h includes xreg_cortexa53.h and xpseudo_asm_gcc.h.
The xreg_cortexa53.h file contains definitions for inline assembler code. It provides inline definitions for Cortex A53 GPRs, SPRs and floating point registers.
The xpseudo_asm_gcc.h contains the definitions for the most often used inline assembler instructions, available as macros. These can be very useful for tasks such as setting or getting special purpose registers, synchronization, or cache manipulation etc. These inline assembler instructions can be used from drivers and user applications written in C.