linux/arch/mips/kernel/head.S
Thomas Bogendoerfer b83ba0b9df MIPS: of: Introduce helper function to get DTB
Selection of the DTB to be used was burried in more or less readable
code in head.S. Move this code into a inline helper function and
use it.

Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
2021-02-04 13:34:51 +01:00

155 lines
3.8 KiB
ArmAsm

/*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Copyright (C) 1994, 1995 Waldorf Electronics
* Written by Ralf Baechle and Andreas Busse
* Copyright (C) 1994 - 99, 2003, 06 Ralf Baechle
* Copyright (C) 1996 Paul M. Antoine
* Modified for DECStation and hence R3000 support by Paul M. Antoine
* Further modifications by David S. Miller and Harald Koerfgen
* Copyright (C) 1999 Silicon Graphics, Inc.
* Kevin Kissell, kevink@mips.com and Carsten Langgaard, carstenl@mips.com
* Copyright (C) 2000 MIPS Technologies, Inc. All rights reserved.
*/
#include <linux/init.h>
#include <linux/threads.h>
#include <asm/addrspace.h>
#include <asm/asm.h>
#include <asm/asmmacro.h>
#include <asm/irqflags.h>
#include <asm/regdef.h>
#include <asm/mipsregs.h>
#include <asm/stackframe.h>
#include <kernel-entry-init.h>
/*
* For the moment disable interrupts, mark the kernel mode and
* set ST0_KX so that the CPU does not spit fire when using
* 64-bit addresses. A full initialization of the CPU's status
* register is done later in per_cpu_trap_init().
*/
.macro setup_c0_status set clr
.set push
mfc0 t0, CP0_STATUS
or t0, ST0_KERNEL_CUMASK|\set|0x1f|\clr
xor t0, 0x1f|\clr
mtc0 t0, CP0_STATUS
.set noreorder
sll zero,3 # ehb
.set pop
.endm
.macro setup_c0_status_pri
#ifdef CONFIG_64BIT
setup_c0_status ST0_KX 0
#else
setup_c0_status 0 0
#endif
.endm
.macro setup_c0_status_sec
#ifdef CONFIG_64BIT
setup_c0_status ST0_KX ST0_BEV
#else
setup_c0_status 0 ST0_BEV
#endif
.endm
#ifndef CONFIG_NO_EXCEPT_FILL
/*
* Reserved space for exception handlers.
* Necessary for machines which link their kernels at KSEG0.
*/
.fill 0x400
#endif
EXPORT(_stext)
#ifdef CONFIG_BOOT_RAW
/*
* Give us a fighting chance of running if execution beings at the
* kernel load address. This is needed because this platform does
* not have a ELF loader yet.
*/
FEXPORT(__kernel_entry)
j kernel_entry
#endif /* CONFIG_BOOT_RAW */
__REF
NESTED(kernel_entry, 16, sp) # kernel entry point
kernel_entry_setup # cpu specific setup
setup_c0_status_pri
/* We might not get launched at the address the kernel is linked to,
so we jump there. */
PTR_LA t0, 0f
jr t0
0:
PTR_LA t0, __bss_start # clear .bss
LONG_S zero, (t0)
PTR_LA t1, __bss_stop - LONGSIZE
1:
PTR_ADDIU t0, LONGSIZE
LONG_S zero, (t0)
bne t0, t1, 1b
LONG_S a0, fw_arg0 # firmware arguments
LONG_S a1, fw_arg1
LONG_S a2, fw_arg2
LONG_S a3, fw_arg3
MTC0 zero, CP0_CONTEXT # clear context register
#ifdef CONFIG_64BIT
MTC0 zero, CP0_XCONTEXT
#endif
PTR_LA $28, init_thread_union
/* Set the SP after an empty pt_regs. */
PTR_LI sp, _THREAD_SIZE - 32 - PT_SIZE
PTR_ADDU sp, $28
back_to_back_c0_hazard
set_saved_sp sp, t0, t1
PTR_SUBU sp, 4 * SZREG # init stack pointer
#ifdef CONFIG_RELOCATABLE
/* Copy kernel and apply the relocations */
jal relocate_kernel
/* Repoint the sp into the new kernel image */
PTR_LI sp, _THREAD_SIZE - 32 - PT_SIZE
PTR_ADDU sp, $28
set_saved_sp sp, t0, t1
PTR_SUBU sp, 4 * SZREG # init stack pointer
/*
* relocate_kernel returns the entry point either
* in the relocated kernel or the original if for
* some reason relocation failed - jump there now
* with instruction hazard barrier because of the
* newly sync'd icache.
*/
jr.hb v0
#else /* !CONFIG_RELOCATABLE */
j start_kernel
#endif /* !CONFIG_RELOCATABLE */
END(kernel_entry)
#ifdef CONFIG_SMP
/*
* SMP slave cpus entry point. Board specific code for bootstrap calls this
* function after setting up the stack and gp registers.
*/
NESTED(smp_bootstrap, 16, sp)
smp_slave_setup
setup_c0_status_sec
j start_secondary
END(smp_bootstrap)
#endif /* CONFIG_SMP */