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/*
* arch/ppc/boot/simple/head.S
*
* Initial board bringup code for many different boards.
*
* Author: Tom Rini
* trini@mvista.com
* Derived from arch/ppc/boot/prep/head.S (Cort Dougan, many others).
*
* 2001-2004 (c) MontaVista, Software, Inc. This file is licensed under
* the terms of the GNU General Public License version 2. This program
* is licensed "as is" without any warranty of any kind, whether express
* or implied.
*/
#include <linux/config.h>
#include <asm/reg.h>
#include <asm/cache.h>
#include <asm/ppc_asm.h>
.text
/*
* Begin at some arbitrary location in RAM or Flash
* Initialize core registers
* Configure memory controller (Not executing from RAM)
* Move the boot code to the link address (8M)
* Setup C stack
* Initialize UART
* Decompress the kernel to 0x0
* Jump to the kernel entry
*
*/
.globl start
start:
bl start_
#ifdef CONFIG_IBM_OPENBIOS
/* The IBM "Tree" bootrom knows that the address of the bootrom
* read only structure is 4 bytes after _start.
*/
.long 0x62726f6d # structure ID - "brom"
.long 0x5f726f00 # - "_ro\0"
.long 1 # structure version
.long bootrom_cmdline # address of *bootrom_cmdline
#endif
start_:
#ifdef CONFIG_FORCE
/* We have some really bad firmware. We must disable the L1
* icache/dcache now or the board won't boot.
*/
li r4,0x0000
isync
mtspr SPRN_HID0,r4
sync
isync
#endif
#if defined(CONFIG_MBX) || defined(CONFIG_RPX8260) || defined(CONFIG_PPC_PREP)
mr r29,r3 /* On the MBX860, r3 is the board info pointer.
* On the RPXSUPER, r3 points to the NVRAM
* configuration keys.
* On PReP, r3 is the pointer to the residual data.
*/
#endif
mflr r3 /* Save our actual starting address. */
/* The following functions we call must not modify r3 or r4.....
*/
#ifdef CONFIG_6xx
/* On PReP we must look at the OpenFirmware pointer and sanity
* test it. On other platforms, we disable the MMU right now
* and other bits.
*/
#ifdef CONFIG_PPC_PREP
/*
* Save the OF pointer to r25, but only if the entry point is in a sane
* location; if not we store 0. If there is no entry point, or it is
* invalid, we establish the default MSR value immediately. Otherwise,
* we defer doing that, to allow OF functions to be called, until we
* begin uncompressing the kernel.
*/
lis r8,0x0fff /* r8 = 0x0fffffff */
ori r8,r8,0xffff
subc r8,r8,r5 /* r8 = (r5 <= r8) ? ~0 : 0 */
subfe r8,r8,r8
nand r8,r8,r8
and. r5,r5,r8 /* r5 will be cleared if (r5 > r8) */
bne+ haveOF
li r8,MSR_IP|MSR_FP /* Not OF: set MSR immediately */
mtmsr r8
isync
haveOF:
mr r25,r5
#else
bl disable_6xx_mmu
#endif
bl disable_6xx_l1cache
CLEAR_CACHES
#endif
#ifdef CONFIG_8xx
mfmsr r8 /* Turn off interrupts */
li r9,0
ori r9,r9,MSR_EE
andc r8,r8,r9
mtmsr r8
/* We do this because some boot roms don't initialize the
* processor correctly. Don't do this if you want to debug
* using a BDM device.
*/
li r4,0 /* Zero DER to prevent FRZ */
mtspr SPRN_DER,r4
#endif
#if defined(CONFIG_MBX) || defined(CONFIG_RPX8260) || defined(CONFIG_PPC_PREP)
mr r4,r29 /* put the board info pointer where the relocate
* routine will find it
*/
#endif
/* Get the load address.
*/
subi r3, r3, 4 /* Get the actual IP, not NIP */
b relocate
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