/* Copyright 2000  AG Electronics Ltd. */
/* This code is distributed without warranty under the GPL v2 (see COPYING) */

/*
 * The aim of this code is to bring the machine from power-on to the point 
 * where we can jump to the the main LinuxBIOS entry point hardwaremain()
 * which is written in C.
 *
 * At power-on, we have no RAM, a memory-mapped I/O space, and we are executing
 * out of ROM, generally at 0xfff00100.
 *
 * Before we jump to harwaremain() we want to do the following:
 *
 * - enable L1 I/D caches, otherwise performance will be slow
 * - set up DBATs for the following regions:
 *   - RAM (generally 0x00000000 -> 0x7fffffff)
 *   - ROM (_ROMBASE -> _ROMBASE + ROM_SIZE)
 *   - I/O (generally 0xfc000000 -> 0xfdffffff)
 *   - the main purpose for setting up the DBATs is so the I/O region
 *     can be marked cache inhibited/write through
 * - set up IBATs for RAM and ROM
 *
 */

#define BSP_IOREGION1	0x80000000
#define BSP_IOMASK1	BAT_BL_256M | BAT_VALID_SUPERVISOR | BAT_VALID_USER
#define BSP_IOREGION2	0xFD000000
#define BSP_IOMASK2	BAT_BL_64M | BAT_VALID_SUPERVISOR | BAT_VALID_USER

        isync

	/* 
	 * Disable dcache and MMU, so we're in a known state
	 */   
        li      r0, 0
	sync
        mtspr	HID0, r0
        sync
        mtmsr	r0 
        isync

	/*
	 * Invalidate D & I BATS
	 */
        mtibatu 0, r0
        mtibatu 1, r0
        mtibatu 2, r0
        mtibatu 3, r0
	isync
        mtdbatu 0, r0
        mtdbatu 1, r0
        mtdbatu 2, r0
        mtdbatu 3, r0
	isync

	/*
	 * Clear segment registers (LinuxBIOS doesn't use these)
	 */
	li	r3, 15
1:	mtsrin  r3, r0
	subic.	r3, r3, 1
	bge	1b
	isync

        /*
	 * Set up DBATs 
	 *
	 * DBAT0 covers RAM (0 -> 0x0FFFFFFF) (256Mb)
	 * DBAT1 covers PCI memory and ROM (0xFD000000 -> 0xFFFFFFFF) (64Mb)
	 * DBAT2 covers PCI memory (0x80000000 -> 0x8FFFFFFF) (256Mb)
	 * DBAT3 is not used
	 */
        lis     r2, 0@h
        ori     r3, r2, BAT_BL_256M | BAT_VALID_SUPERVISOR | BAT_VALID_USER
        ori     r2, r2, BAT_READ_WRITE | BAT_GUARDED
        mtdbatu 0, r3
        mtdbatl 0, r2
	isync

        lis     r2, BSP_IOREGION2@h
        ori     r3, r2, BAT_BL_64M | BAT_VALID_SUPERVISOR | BAT_VALID_USER
        ori     r2, r2, BAT_CACHE_INHIBITED | BAT_GUARDED | BAT_READ_WRITE
        mtdbatu 1, r3
        mtdbatl 1, r2
	isync

        lis     r2, BSP_IOREGION1@h
        ori     r3, r2, BAT_BL_256M | BAT_VALID_SUPERVISOR | BAT_VALID_USER
        ori     r2, r2, BAT_CACHE_INHIBITED | BAT_GUARDED | BAT_READ_WRITE
        mtdbatu 2, r3
        mtdbatl 2, r2
	isync

	/*
	 * IBATS
	 *
	 * IBAT0 covers RAM (0 -> 256Mb)
	 * IBAT1 covers ROM (_ROMBASE -> _ROMBASE+ROM_SIZE)
	 */
        lis     r2, 0@h
        ori     r3, r2, BAT_BL_256M | BAT_VALID_SUPERVISOR | BAT_VALID_USER
        ori     r2, r2, BAT_READ_WRITE
        mtibatu 0, r3
        mtibatl 0, r2
	isync

        lis     r2, _ROMBASE@h
#if ROM_SIZE > 1048576
        ori     r3, r2, BAT_BL_16M | BAT_VALID_SUPERVISOR | BAT_VALID_USER
#else
        ori     r3, r2, BAT_BL_1M | BAT_VALID_SUPERVISOR | BAT_VALID_USER
#endif
        ori     r2, r2, BAT_READ_ONLY
        mtibatu 1, r3
        mtibatl 1, r2
	isync

        /*
	 * Enable MMU 
	 */
        mfmsr   r2
        ori     r2, r2, MSR_DR | MSR_IR
        mtmsr   r2
        isync
	sync

        /*
	 * Enable and invalidate the L1 icache 
	 */
        mfspr   r2, HID0
        ori     r2, r2, HID0_ICE | HID0_ICFI
	isync
        mtspr   HID0, r2
        /*
	 * Enable and invalidate the L1 dcache 
	 */
        mfspr   r2, HID0
        ori     r2, r2, HID0_DCE | HID0_DCFI
	sync
        mtspr   HID0, r2

	/*
	 * Initialize data cache blocks 
	 * (assumes cache block size of 32 bytes)
	 */
	lis	r1, DCACHE_RAM_BASE@h
	ori	r1, r1, DCACHE_RAM_BASE@l
	li 	r3, (DCACHE_RAM_SIZE / 32)
	mtctr	r3
0:	dcbz	r0, r1
	addi	r1, r1, 32
	bdnz	0b