linux/arch/sh/kernel/head.S
Paul Mundt aba1030a7e sh: Bring SMP support back from the dead.
There was a very preliminary bunch of SMP code scattered around for the
SH7604 microcontrollers from way back when, and it has mostly suffered
bitrot since then. With the tree already having been slowly getting
prepped for SMP, this plugs in most of the remaining platform-independent
bits.

Signed-off-by: Magnus Damm <damm@igel.co.jp>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2007-09-21 18:32:32 +09:00

121 lines
2.5 KiB
ArmAsm

/* $Id: head.S,v 1.7 2003/09/01 17:58:19 lethal Exp $
*
* arch/sh/kernel/head.S
*
* Copyright (C) 1999, 2000 Niibe Yutaka & Kaz Kojima
*
* 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.
*
* Head.S contains the SH exception handlers and startup code.
*/
#include <linux/linkage.h>
#include <asm/thread_info.h>
#ifdef CONFIG_CPU_SH4A
#define SYNCO() synco
#define PREFI(label, reg) \
mov.l label, reg; \
prefi @reg
#else
#define SYNCO()
#define PREFI(label, reg)
#endif
.section .empty_zero_page, "aw"
ENTRY(empty_zero_page)
.long 1 /* MOUNT_ROOT_RDONLY */
.long 0 /* RAMDISK_FLAGS */
.long 0x0200 /* ORIG_ROOT_DEV */
.long 1 /* LOADER_TYPE */
.long 0x00360000 /* INITRD_START */
.long 0x000a0000 /* INITRD_SIZE */
.long 0
1:
.skip PAGE_SIZE - empty_zero_page - 1b
.section .text.head, "ax"
/*
* Condition at the entry of _stext:
*
* BSC has already been initialized.
* INTC may or may not be initialized.
* VBR may or may not be initialized.
* MMU may or may not be initialized.
* Cache may or may not be initialized.
* Hardware (including on-chip modules) may or may not be initialized.
*
*/
ENTRY(_stext)
! Initialize Status Register
mov.l 1f, r0 ! MD=1, RB=0, BL=0, IMASK=0xF
ldc r0, sr
! Initialize global interrupt mask
#ifdef CONFIG_CPU_HAS_SR_RB
mov #0, r0
ldc r0, r6_bank
#endif
/*
* Prefetch if possible to reduce cache miss penalty.
*
* We do this early on for SH-4A as a micro-optimization,
* as later on we will have speculative execution enabled
* and this will become less of an issue.
*/
PREFI(5f, r0)
PREFI(6f, r0)
!
mov.l 2f, r0
mov r0, r15 ! Set initial r15 (stack pointer)
#ifdef CONFIG_CPU_HAS_SR_RB
mov.l 7f, r0
ldc r0, r7_bank ! ... and initial thread_info
#endif
! Clear BSS area
#ifdef CONFIG_SMP
mov.l 3f, r0
cmp/eq #0, r0 ! skip clear if set to zero
bt 10f
#endif
mov.l 3f, r1
add #4, r1
mov.l 4f, r2
mov #0, r0
9: cmp/hs r2, r1
bf/s 9b ! while (r1 < r2)
mov.l r0,@-r2
10:
! Additional CPU initialization
mov.l 6f, r0
jsr @r0
nop
SYNCO() ! Wait for pending instructions..
! Start kernel
mov.l 5f, r0
jmp @r0
nop
.balign 4
#if defined(CONFIG_CPU_SH2)
1: .long 0x000000F0 ! IMASK=0xF
#else
1: .long 0x400080F0 ! MD=1, RB=0, BL=0, FD=1, IMASK=0xF
#endif
ENTRY(stack_start)
2: .long init_thread_union+THREAD_SIZE
3: .long __bss_start
4: .long _end
5: .long start_kernel
6: .long sh_cpu_init
7: .long init_thread_union