pcb_addr          167 arch/powerpc/include/asm/opal.h int64_t opal_xscom_read(uint32_t gcid, uint64_t pcb_addr, __be64 *val);
pcb_addr          168 arch/powerpc/include/asm/opal.h int64_t opal_xscom_write(uint32_t gcid, uint64_t pcb_addr, uint64_t val);