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/* linux/arch/arm/plat-s3c24xx/sleep.S
*
* Copyright (c) 2004 Simtec Electronics
* Ben Dooks <ben@simtec.co.uk>
*
* S3C2410 Power Manager (Suspend-To-RAM) support
*
* Based on PXA/SA1100 sleep code by:
* Nicolas Pitre, (c) 2002 Monta Vista Software Inc
* Cliff Brake, (c) 2001
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include <linux/linkage.h>
#include <asm/assembler.h>
#include <mach/hardware.h>
#include <mach/map.h>
#include <mach/regs-gpio.h>
#include <mach/regs-clock.h>
#include <mach/regs-mem.h>
#include <plat/regs-serial.h>
/* CONFIG_DEBUG_RESUME is dangerous if your bootloader does not
* reset the UART configuration, only enable if you really need this!
*/
//#define CONFIG_DEBUG_RESUME
.text
/* s3c_cpu_save
*
* save enough of the CPU state to allow us to re-start
* pm.c code. as we store items like the sp/lr, we will
* end up returning from this function when the cpu resumes
* so the return value is set to mark this.
*
* This arangement means we avoid having to flush the cache
* from this code.
*
* entry:
* r0 = pointer to save block
*
* exit:
* r0 = 0 => we stored everything
* 1 => resumed from sleep
*/
ENTRY(s3c_cpu_save)
stmfd sp!, { r4 - r12, lr }
@@ store co-processor registers
mrc p15, 0, r4, c13, c0, 0 @ PID
mrc p15, 0, r5, c3, c0, 0 @ Domain ID
mrc p15, 0, r6, c2, c0, 0 @ translation table base address
mrc p15, 0, r7, c1, c0, 0 @ control register
stmia r0, { r4 - r13 }
mov r0, #0
ldmfd sp, { r4 - r12, pc }
@@ return to the caller, after having the MMU
@@ turned on, this restores the last bits from the
@@ stack
resume_with_mmu:
mov r0, #1
ldmfd sp!, { r4 - r12, pc }
.ltorg
@@ the next bits sit in the .data segment, even though they
@@ happen to be code... the s3c_sleep_save_phys needs to be
@@ accessed by the resume code before it can restore the MMU.
@@ This means that the variable has to be close enough for the
@@ code to read it... since the .text segment needs to be RO,
@@ the data segment can be the only place to put this code.
.data
.global s3c_sleep_save_phys
s3c_sleep_save_phys:
.word 0
/* sleep magic, to allow the bootloader to check for an valid
* image to resume to. Must be the first word before the
* s3c_cpu_resume entry.
*/
.word 0x2bedf00d
/* s3c_cpu_resume
*
* resume code entry for bootloader to call
*
* we must put this code here in the data segment as we have no
* other way of restoring the stack pointer after sleep, and we
* must not write to the code segment (code is read-only)
*/
ENTRY(s3c_cpu_resume)
mov r0, #PSR_I_BIT | PSR_F_BIT | SVC_MODE
msr cpsr_c, r0
@@ load UART to allow us to print the two characters for
@@ resume debug
mov r2, #S3C24XX_PA_UART & 0xff000000
orr r2, r2, #S3C24XX_PA_UART & 0xff000
#if 0
/* SMDK2440 LED set */
mov r14, #S3C24XX_PA_GPIO
ldr r12, [ r14, #0x54 ]
bic r12, r12, #3<<4
orr r12, r12, #1<<7
str r12, [ r14, #0x54 ]
#endif
#ifdef CONFIG_DEBUG_RESUME
mov r3, #'L'
strb r3, [ r2, #S3C2410_UTXH ]
1001:
ldrb r14, [ r3, #S3C2410_UTRSTAT ]
tst r14, #S3C2410_UTRSTAT_TXE
beq 1001b
#endif /* CONFIG_DEBUG_RESUME */
mov r1, #0
mcr p15, 0, r1, c8, c7, 0 @@ invalidate I & D TLBs
mcr p15, 0, r1, c7, c7, 0 @@ invalidate I & D caches
ldr r0, s3c_sleep_save_phys @ address of restore block
ldmia r0, { r4 - r13 }
mcr p15, 0, r4, c13, c0, 0 @ PID
mcr p15, 0, r5, c3, c0, 0 @ Domain ID
mcr p15, 0, r6, c2, c0, 0 @ translation table base
#ifdef CONFIG_DEBUG_RESUME
mov r3, #'R'
strb r3, [ r2, #S3C2410_UTXH ]
#endif
ldr r2, =resume_with_mmu
mcr p15, 0, r7, c1, c0, 0 @ turn on MMU, etc
nop @ second-to-last before mmu
mov pc, r2 @ go back to virtual address
.ltorg
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