Hi,
bsp_pdi_write_indication is used by application to indicate write to special ESC registers which firmware needs to handle and value is needed only in the case of write to SM PDI control registers (ESC_ADDR_SMx_PDI_CONTROL). Here you just need to pass LSB of 32-bit word assuming start address is ESC_ADDR_SMx_PDI_CONTROL. This is another reason why we preferred 8-bit processing here...