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
52 ENTRY(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
65 loop:
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
81 loop2:
82 subs r5, r5, #0x1
83 bne loop2
84 /* resume*/
85 ldmfd sp!, {r0 - r12, pc} @ restore regs and return
86
87 A_SDRC0:
88 .word A_SDRC0_V
89
90 ENTRY(omap24xx_cpu_suspend_sz)
91 .word . - omap24xx_cpu_suspend