forked from Minki/linux
7a2eacb759
Shoves a magic word in to the empty_zero_page section for the bootloader to work out whether to start the kernel in 29-bit or 32-bit mode. [ Renesas CPUs already take care of the initial PMB mappings entirely in hardware and decide on 29-bit/32-bit physical depending on which pin powered up the CPU, so this is mostly for ST parts. -- PFM ]. Signed-off-by: Stuart Menefy <stuart.menefy@st.com> Signed-off-by: Paul Mundt <lethal@linux-sh.org>
125 lines
2.6 KiB
ArmAsm
125 lines
2.6 KiB
ArmAsm
/* $Id: head.S,v 1.7 2003/09/01 17:58:19 lethal Exp $
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*
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* arch/sh/kernel/head.S
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*
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* Copyright (C) 1999, 2000 Niibe Yutaka & Kaz Kojima
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*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file "COPYING" in the main directory of this archive
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* for more details.
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*
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* Head.S contains the SH exception handlers and startup code.
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*/
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#include <linux/linkage.h>
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#include <asm/thread_info.h>
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#ifdef CONFIG_CPU_SH4A
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#define SYNCO() synco
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#define PREFI(label, reg) \
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mov.l label, reg; \
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prefi @reg
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#else
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#define SYNCO()
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#define PREFI(label, reg)
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#endif
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.section .empty_zero_page, "aw"
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ENTRY(empty_zero_page)
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.long 1 /* MOUNT_ROOT_RDONLY */
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.long 0 /* RAMDISK_FLAGS */
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.long 0x0200 /* ORIG_ROOT_DEV */
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.long 1 /* LOADER_TYPE */
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.long 0x00360000 /* INITRD_START */
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.long 0x000a0000 /* INITRD_SIZE */
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#ifdef CONFIG_32BIT
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.long 0x53453f00 + 32 /* "SE?" = 32 bit */
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#else
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.long 0x53453f00 + 29 /* "SE?" = 29 bit */
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#endif
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1:
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.skip PAGE_SIZE - empty_zero_page - 1b
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.section .text.head, "ax"
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/*
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* Condition at the entry of _stext:
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*
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* BSC has already been initialized.
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* INTC may or may not be initialized.
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* VBR may or may not be initialized.
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* MMU may or may not be initialized.
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* Cache may or may not be initialized.
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* Hardware (including on-chip modules) may or may not be initialized.
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*
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*/
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ENTRY(_stext)
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! Initialize Status Register
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mov.l 1f, r0 ! MD=1, RB=0, BL=0, IMASK=0xF
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ldc r0, sr
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! Initialize global interrupt mask
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#ifdef CONFIG_CPU_HAS_SR_RB
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mov #0, r0
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ldc r0, r6_bank
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#endif
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/*
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* Prefetch if possible to reduce cache miss penalty.
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*
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* We do this early on for SH-4A as a micro-optimization,
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* as later on we will have speculative execution enabled
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* and this will become less of an issue.
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*/
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PREFI(5f, r0)
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PREFI(6f, r0)
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!
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mov.l 2f, r0
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mov r0, r15 ! Set initial r15 (stack pointer)
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#ifdef CONFIG_CPU_HAS_SR_RB
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mov.l 7f, r0
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ldc r0, r7_bank ! ... and initial thread_info
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#endif
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! Clear BSS area
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#ifdef CONFIG_SMP
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mov.l 3f, r0
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cmp/eq #0, r0 ! skip clear if set to zero
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bt 10f
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#endif
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mov.l 3f, r1
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add #4, r1
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mov.l 4f, r2
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mov #0, r0
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9: cmp/hs r2, r1
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bf/s 9b ! while (r1 < r2)
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mov.l r0,@-r2
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10:
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! Additional CPU initialization
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mov.l 6f, r0
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jsr @r0
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nop
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SYNCO() ! Wait for pending instructions..
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! Start kernel
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mov.l 5f, r0
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jmp @r0
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nop
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.balign 4
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#if defined(CONFIG_CPU_SH2)
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1: .long 0x000000F0 ! IMASK=0xF
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#else
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1: .long 0x400080F0 ! MD=1, RB=0, BL=0, FD=1, IMASK=0xF
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#endif
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ENTRY(stack_start)
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2: .long init_thread_union+THREAD_SIZE
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3: .long __bss_start
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4: .long _end
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5: .long start_kernel
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6: .long sh_cpu_init
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7: .long init_thread_union
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