/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
* linux/arch/arm/mach-omap2/sleep.S
*
* (C) Copyright 2004
* Texas Instruments, <www.ti.com>
* Richard Woodruff <[email protected]>
*
* (C) Copyright 2006 Nokia Corporation
* Fixed idle loop sleep
* Igor Stoppa <[email protected]>
*/
#include <linux/linkage.h>
#include <asm/assembler.h>
#include "omap24xx.h"
#include "sdrc.h"
/* First address of reserved address space? apparently valid for OMAP2 & 3 */
#define A_SDRC0_V (0xC0000000)
.text
/*
* omap24xx_cpu_suspend() - Forces OMAP into deep sleep state by completing
* SDRC shutdown then ARM shutdown. Upon wake MPU is back on so just restore
* SDRC.
*
* Input:
* R0 : DLL ctrl value pre-Sleep
* R1 : SDRC_DLLA_CTRL
* R2 : SDRC_POWER
*
* The if the DPLL is going to AutoIdle. It seems like the DPLL may be back on
* when we get called, but the DLL probably isn't. We will wait a bit more in
* case the DPLL isn't quite there yet. The code will wait on DLL for DDR even
* if in unlocked mode.
*
* For less than 242x-ES2.2 upon wake from a sleep mode where the external
* oscillator was stopped, a timing bug exists where a non-stabilized 12MHz
* clock can pass into the PRCM can cause problems at DSP and IVA.
* To work around this the code will switch to the 32kHz source prior to sleep.
* Post sleep we will shift back to using the DPLL. Apparently,
* CM_IDLEST_CLKGEN does not reflect the full clock change so you need to wait
* 3x12MHz + 3x32kHz clocks for a full switch.
*
* The DLL load value is not kept in RETENTION or OFF. It needs to be restored
* at wake
*/
.align 3
ENTRY(omap24xx_cpu_suspend)
stmfd sp!, {r0 - r12, lr} @ save registers on stack
mov r3, #0x0 @ clear for mcr call
mcr p15, 0, r3, c7, c10, 4 @ memory barrier, hope SDR/DDR finished
nop
nop
ldr r4, [r2] @ read SDRC_POWER
orr r4, r4, #0x40 @ enable self refresh on idle req
mov r5, #0x2000 @ set delay (DPLL relock + DLL relock)
str r4, [r2] @ make it so
nop
mcr p15, 0, r3, c7, c0, 4 @ wait for interrupt
nop
loop:
subs r5, r5, #0x1 @ awake, wait just a bit
bne loop
/* The DPLL has to be on before we take the DDR out of self refresh */
bic r4, r4, #0x40 @ now clear self refresh bit.
str r4, [r2] @ write to SDRC_POWER
ldr r4, A_SDRC0 @ make a clock happen
ldr r4, [r4] @ read A_SDRC0
nop @ start auto refresh only after clk ok
movs r0, r0 @ see if DDR or SDR
strne r0, [r1] @ rewrite DLLA to force DLL reload
addne r1, r1, #0x8 @ move to DLLB
strne r0, [r1] @ rewrite DLLB to force DLL reload
mov r5, #0x1000
loop2:
subs r5, r5, #0x1
bne loop2
/* resume*/
ldmfd sp!, {r0 - r12, pc} @ restore regs and return
A_SDRC0:
.word A_SDRC0_V
ENTRY(omap24xx_cpu_suspend_sz)
.word . - omap24xx_cpu_suspend
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