xref: /openbmc/linux/arch/arm/mach-omap2/sleep33xx.S (revision 6a87e0f0) 
1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 * Low level suspend code for AM33XX SoCs
4 *
5 * Copyright (C) 2012-2018 Texas Instruments Incorporated - https://www.ti.com/
6 *	Dave Gerlach, Vaibhav Bedia
7 */
8
9#include <linux/linkage.h>
10#include <linux/platform_data/pm33xx.h>
11#include <linux/ti-emif-sram.h>
12#include <asm/assembler.h>
13#include <asm/page.h>
14
15#include "iomap.h"
16#include "cm33xx.h"
17#include "pm-asm-offsets.h"
18
19#define AM33XX_CM_CLKCTRL_MODULESTATE_DISABLED			0x00030000
20#define AM33XX_CM_CLKCTRL_MODULEMODE_DISABLE			0x0003
21#define AM33XX_CM_CLKCTRL_MODULEMODE_ENABLE			0x0002
22
23/* replicated define because linux/bitops.h cannot be included in assembly */
24#define BIT(nr)			(1 << (nr))
25
26	.arm
27	.arch armv7-a
28	.align 3
29
30ENTRY(am33xx_do_wfi)
31	stmfd	sp!, {r4 - r11, lr}	@ save registers on stack
32
33	/* Save wfi_flags arg to data space */
34	mov	r4, r0
35	adr	r3, am33xx_pm_ro_sram_data
36	ldr	r2, [r3, #AMX3_PM_RO_SRAM_DATA_VIRT_OFFSET]
37	str	r4, [r2, #AMX3_PM_WFI_FLAGS_OFFSET]
38
39	/* Only flush cache is we know we are losing MPU context */
40	tst	r4, #WFI_FLAG_FLUSH_CACHE
41	beq	cache_skip_flush
42
43	/*
44	 * Flush all data from the L1 and L2 data cache before disabling
45	 * SCTLR.C bit.
46	 */
47	ldr	r1, kernel_flush
48	blx	r1
49
50	/*
51	 * Clear the SCTLR.C bit to prevent further data cache
52	 * allocation. Clearing SCTLR.C would make all the data accesses
53	 * strongly ordered and would not hit the cache.
54	 */
55	mrc	p15, 0, r0, c1, c0, 0
56	bic	r0, r0, #(1 << 2)	@ Disable the C bit
57	mcr	p15, 0, r0, c1, c0, 0
58	isb
59
60	/*
61	 * Invalidate L1 and L2 data cache.
62	 */
63	ldr	r1, kernel_flush
64	blx	r1
65
66	adr	r3, am33xx_pm_ro_sram_data
67	ldr	r2, [r3, #AMX3_PM_RO_SRAM_DATA_VIRT_OFFSET]
68	ldr	r4, [r2, #AMX3_PM_WFI_FLAGS_OFFSET]
69
70cache_skip_flush:
71	/* Check if we want self refresh */
72	tst	r4, #WFI_FLAG_SELF_REFRESH
73	beq	emif_skip_enter_sr
74
75	adr	r9, am33xx_emif_sram_table
76
77	ldr	r3, [r9, #EMIF_PM_ENTER_SR_OFFSET]
78	blx	r3
79
80emif_skip_enter_sr:
81	/* Only necessary if PER is losing context */
82	tst	r4, #WFI_FLAG_SAVE_EMIF
83	beq	emif_skip_save
84
85	ldr	r3, [r9, #EMIF_PM_SAVE_CONTEXT_OFFSET]
86	blx	r3
87
88emif_skip_save:
89	/* Only can disable EMIF if we have entered self refresh */
90	tst     r4, #WFI_FLAG_SELF_REFRESH
91	beq     emif_skip_disable
92
93	/* Disable EMIF */
94	ldr     r1, virt_emif_clkctrl
95	ldr     r2, [r1]
96	bic     r2, r2, #AM33XX_CM_CLKCTRL_MODULEMODE_DISABLE
97	str     r2, [r1]
98
99	ldr	r1, virt_emif_clkctrl
100wait_emif_disable:
101	ldr	r2, [r1]
102	mov	r3, #AM33XX_CM_CLKCTRL_MODULESTATE_DISABLED
103	cmp	r2, r3
104	bne	wait_emif_disable
105
106emif_skip_disable:
107	tst	r4, #WFI_FLAG_WAKE_M3
108	beq	wkup_m3_skip
109
110	/*
111	 * For the MPU WFI to be registered as an interrupt
112	 * to WKUP_M3, MPU_CLKCTRL.MODULEMODE needs to be set
113	 * to DISABLED
114	 */
115	ldr	r1, virt_mpu_clkctrl
116	ldr	r2, [r1]
117	bic	r2, r2, #AM33XX_CM_CLKCTRL_MODULEMODE_DISABLE
118	str	r2, [r1]
119
120wkup_m3_skip:
121	/*
122	 * Execute an ISB instruction to ensure that all of the
123	 * CP15 register changes have been committed.
124	 */
125	isb
126
127	/*
128	 * Execute a barrier instruction to ensure that all cache,
129	 * TLB and branch predictor maintenance operations issued
130	 * have completed.
131	 */
132	dsb
133	dmb
134
135	/*
136	 * Execute a WFI instruction and wait until the
137	 * STANDBYWFI output is asserted to indicate that the
138	 * CPU is in idle and low power state. CPU can specualatively
139	 * prefetch the instructions so add NOPs after WFI. Thirteen
140	 * NOPs as per Cortex-A8 pipeline.
141	 */
142	wfi
143
144	nop
145	nop
146	nop
147	nop
148	nop
149	nop
150	nop
151	nop
152	nop
153	nop
154	nop
155	nop
156	nop
157
158	/* We come here in case of an abort due to a late interrupt */
159
160	/* Set MPU_CLKCTRL.MODULEMODE back to ENABLE */
161	ldr	r1, virt_mpu_clkctrl
162	mov	r2, #AM33XX_CM_CLKCTRL_MODULEMODE_ENABLE
163	str	r2, [r1]
164
165	/* Re-enable EMIF */
166	ldr	r1, virt_emif_clkctrl
167	mov	r2, #AM33XX_CM_CLKCTRL_MODULEMODE_ENABLE
168	str	r2, [r1]
169wait_emif_enable:
170	ldr	r3, [r1]
171	cmp	r2, r3
172	bne	wait_emif_enable
173
174	/* Only necessary if PER is losing context */
175	tst	r4, #WFI_FLAG_SELF_REFRESH
176	beq	emif_skip_exit_sr_abt
177
178	adr	r9, am33xx_emif_sram_table
179	ldr	r1, [r9, #EMIF_PM_ABORT_SR_OFFSET]
180	blx	r1
181
182emif_skip_exit_sr_abt:
183	tst	r4, #WFI_FLAG_FLUSH_CACHE
184	beq	cache_skip_restore
185
186	/*
187	 * Set SCTLR.C bit to allow data cache allocation
188	 */
189	mrc	p15, 0, r0, c1, c0, 0
190	orr	r0, r0, #(1 << 2)	@ Enable the C bit
191	mcr	p15, 0, r0, c1, c0, 0
192	isb
193
194cache_skip_restore:
195	/* Let the suspend code know about the abort */
196	mov	r0, #1
197	ldmfd	sp!, {r4 - r11, pc}	@ restore regs and return
198ENDPROC(am33xx_do_wfi)
199
200	.align
201ENTRY(am33xx_resume_offset)
202	.word . - am33xx_do_wfi
203
204ENTRY(am33xx_resume_from_deep_sleep)
205	/* Re-enable EMIF */
206	ldr	r0, phys_emif_clkctrl
207	mov	r1, #AM33XX_CM_CLKCTRL_MODULEMODE_ENABLE
208	str	r1, [r0]
209wait_emif_enable1:
210	ldr	r2, [r0]
211	cmp	r1, r2
212	bne	wait_emif_enable1
213
214	adr	r9, am33xx_emif_sram_table
215
216	ldr	r1, [r9, #EMIF_PM_RESTORE_CONTEXT_OFFSET]
217	blx	r1
218
219	ldr	r1, [r9, #EMIF_PM_EXIT_SR_OFFSET]
220	blx	r1
221
222resume_to_ddr:
223	/* We are back. Branch to the common CPU resume routine */
224	mov	r0, #0
225	ldr	pc, resume_addr
226ENDPROC(am33xx_resume_from_deep_sleep)
227
228/*
229 * Local variables
230 */
231	.align
232kernel_flush:
233	.word   v7_flush_dcache_all
234virt_mpu_clkctrl:
235	.word	AM33XX_CM_MPU_MPU_CLKCTRL
236virt_emif_clkctrl:
237	.word	AM33XX_CM_PER_EMIF_CLKCTRL
238phys_emif_clkctrl:
239	.word	(AM33XX_CM_BASE + AM33XX_CM_PER_MOD + \
240		AM33XX_CM_PER_EMIF_CLKCTRL_OFFSET)
241
242.align 3
243/* DDR related defines */
244am33xx_emif_sram_table:
245	.space EMIF_PM_FUNCTIONS_SIZE
246
247ENTRY(am33xx_pm_sram)
248	.word am33xx_do_wfi
249	.word am33xx_do_wfi_sz
250	.word am33xx_resume_offset
251	.word am33xx_emif_sram_table
252	.word am33xx_pm_ro_sram_data
253
254resume_addr:
255.word  cpu_resume - PAGE_OFFSET + 0x80000000
256
257.align 3
258ENTRY(am33xx_pm_ro_sram_data)
259	.space AMX3_PM_RO_SRAM_DATA_SIZE
260
261ENTRY(am33xx_do_wfi_sz)
262	.word	. - am33xx_do_wfi
263