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+/* 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 <r-woodruff2@ti.com>
+ *
+ * (C) Copyright 2006 Nokia Corporation
+ * Fixed idle loop sleep
+ * Igor Stoppa <igor.stoppa@nokia.com>
+ */
+
+#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