Hi,

I need a software mechanism to reboot my system (MPC8323) and I tried the shutdown utility, but it show some exception 
while rebooting and doesn't restart the system properly.
So, I decided to understand the following code taken from the directory given below
	bsp-nto640-freescale-mpc8323e-rdb-trunk/src/hardware/startup/boards/mpc8323e-rdb

filename:- callout_reboot_8323rdb.s

.include "callout.ah"		
patcher:
	# R3: syspage paddr
	# R4: syspage vaddr
	# R5: rtn dst offset
	# R6: r/w offset
	# R7: patch data
	# R8: rtn src

	stwu    %r1, -32(%r1)
	mflr    %r0
	stw     %r31, 28(%r1)
	stw     %r0, 36(%r1)
	add     %r31,%r3,%r5
	loadi	%r4, 0xF8000000
	loadi   %r3, 32
	bl      callout_io_map
	sth     %r3, 6(%r31)
	srwi    %r3,%r3, 16
	sth     %r3, 2(%r31)
	lwz     %r0, 36(%r1)
	mtlr    %r0
	lwz     %r31, 28(%r1)
	addi    %r1, %r1, 32
	blr

CALLOUT_START	reboot_mpc8323rdb, 0, patcher
	lis		%r4, 0x1234
	ori		%r4, %r4, 0x5678	
	#disable interrupts
	loadi	%r9,PPC_MSR_EE
	mfmsr	%r8
	andc	%r9,%r8,%r9
	mtmsr	%r9
	isync
	lbz		%r0, 7(%r4)
	rlwinm	%r6, %r0, 0, 24, 30
	stb		%r6, 7(%r4)
1:
	b		1b
CALLOUT_END		reboot_mpc8323rdb

But while going through the code we didn't understand what is happenning in it. Plz answer the following querries about 
the code.

a)	Here, Patcher is providing an address to Callout, what is that address?	
b)	What is significance of address 28(%r1), 36(%r1), 6(%r31), 2(%r31), 7(%r4) in the code and what is the link of these 
address with System Page Entries?
c) If possible please explain the complete flow.

Thanks,

Regards
Vijayraj