SWSR register in MPC555

Started by Mohan kumar July 17, 2008
Hi all,

The below line from MPC555, SECTION 6.10.
The SWT service sequence consists of the following two steps:
1. Write 0x556C to the Software Service Register (SWSR)
2. Write 0xAA39 to the SWSR
The service sequence clears the watchdog timer and the timing process
begins again. If any value other than 0x556C or 0xAA39 is written to the
SWSR, the entire sequence must start over.

My question is,
1. Is the user defined software checks whether SWSR is written in proper
sequence or it is inbuilt property in the powerpc processor to find this.