xref: /openbmc/linux/arch/arm/mach-omap2/sleep24xx.S (revision 1a59d1b8)
1/* SPDX-License-Identifier: GPL-2.0-or-later */
2/*
3 * linux/arch/arm/mach-omap2/sleep.S
4 *
5 * (C) Copyright 2004
6 * Texas Instruments, <www.ti.com>
7 * Richard Woodruff <r-woodruff2@ti.com>
8 *
9 * (C) Copyright 2006 Nokia Corporation
10 * Fixed idle loop sleep
11 * Igor Stoppa <igor.stoppa@nokia.com>
12 */
13
14#include <linux/linkage.h>
15#include <asm/assembler.h>
16
17#include "omap24xx.h"
18#include "sdrc.h"
19
20/* First address of reserved address space?  apparently valid for OMAP2 & 3 */
21#define A_SDRC0_V		(0xC0000000)
22
23	.text
24
25/*
26 * omap24xx_cpu_suspend() - Forces OMAP into deep sleep state by completing
27 * SDRC shutdown then ARM shutdown.  Upon wake MPU is back on so just restore
28 * SDRC.
29 *
30 * Input:
31 * R0 :	DLL ctrl value pre-Sleep
32 * R1 : SDRC_DLLA_CTRL
33 * R2 : SDRC_POWER
34 *
35 * The if the DPLL is going to AutoIdle. It seems like the DPLL may be back on
36 * when we get called, but the DLL probably isn't.  We will wait a bit more in
37 * case the DPLL isn't quite there yet. The code will wait on DLL for DDR even
38 * if in unlocked mode.
39 *
40 * For less than 242x-ES2.2 upon wake from a sleep mode where the external
41 * oscillator was stopped, a timing bug exists where a non-stabilized 12MHz
42 * clock can pass into the PRCM can cause problems at DSP and IVA.
43 * To work around this the code will switch to the 32kHz source prior to sleep.
44 * Post sleep we will shift back to using the DPLL.  Apparently,
45 * CM_IDLEST_CLKGEN does not reflect the full clock change so you need to wait
46 * 3x12MHz + 3x32kHz clocks for a full switch.
47 *
48 * The DLL load value is not kept in RETENTION or OFF.	It needs to be restored
49 * at wake
50 */
51	.align	3
52ENTRY(omap24xx_cpu_suspend)
53	stmfd	sp!, {r0 - r12, lr}	@ save registers on stack
54	mov	r3, #0x0		@ clear for mcr call
55	mcr	p15, 0, r3, c7, c10, 4	@ memory barrier, hope SDR/DDR finished
56	nop
57	nop
58	ldr	r4, [r2]		@ read SDRC_POWER
59	orr	r4, r4, #0x40		@ enable self refresh on idle req
60	mov	r5, #0x2000		@ set delay (DPLL relock + DLL relock)
61	str	r4, [r2]		@ make it so
62	nop
63	mcr	p15, 0, r3, c7, c0, 4	@ wait for interrupt
64	nop
65loop:
66	subs	r5, r5, #0x1		@ awake, wait just a bit
67	bne	loop
68
69	/* The DPLL has to be on before we take the DDR out of self refresh */
70	bic	r4, r4, #0x40		@ now clear self refresh bit.
71	str	r4, [r2]		@ write to SDRC_POWER
72	ldr	r4, A_SDRC0		@ make a clock happen
73	ldr	r4, [r4]		@ read A_SDRC0
74	nop				@ start auto refresh only after clk ok
75	movs	r0, r0			@ see if DDR or SDR
76	strne	r0, [r1]		@ rewrite DLLA to force DLL reload
77	addne	r1, r1, #0x8		@ move to DLLB
78	strne	r0, [r1]		@ rewrite DLLB to force DLL reload
79
80	mov	r5, #0x1000
81loop2:
82	subs	r5, r5, #0x1
83	bne	loop2
84	/* resume*/
85	ldmfd	sp!, {r0 - r12, pc}	@ restore regs and return
86
87A_SDRC0:
88	.word A_SDRC0_V
89
90ENTRY(omap24xx_cpu_suspend_sz)
91	.word	. - omap24xx_cpu_suspend
92