1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Copyright (C) 2014 Imagination Technologies Ltd.
4 *
5 * CPU PM notifiers for saving/restoring general CPU state.
6 */
7
8 #include <linux/cpu_pm.h>
9 #include <linux/init.h>
10
11 #include <asm/dsp.h>
12 #include <asm/fpu.h>
13 #include <asm/mmu_context.h>
14 #include <asm/pm.h>
15 #include <asm/watch.h>
16
17 /* Used by PM helper macros in asm/pm.h */
18 struct mips_static_suspend_state mips_static_suspend_state;
19
20 /**
21 * mips_cpu_save() - Save general CPU state.
22 * Ensures that general CPU context is saved, notably FPU and DSP.
23 */
24 static int mips_cpu_save(void)
25 {
26 /* Save FPU state */
27 lose_fpu(1);
28
29 /* Save DSP state */
30 save_dsp(current);
31
32 return 0;
33 }
34
35 /**
36 * mips_cpu_restore() - Restore general CPU state.
37 * Restores important CPU context.
38 */
39 static void mips_cpu_restore(void)
40 {
41 unsigned int cpu = smp_processor_id();
42
43 /* Restore ASID */
44 if (current->mm)
45 write_c0_entryhi(cpu_asid(cpu, current->mm));
46
47 /* Restore DSP state */
48 restore_dsp(current);
49
50 /* Restore UserLocal */
51 if (cpu_has_userlocal)
52 write_c0_userlocal(current_thread_info()->tp_value);
53
54 /* Restore watch registers */
55 __restore_watch(current);
56 }
57
58 /**
59 * mips_pm_notifier() - Notifier for preserving general CPU context.
60 * @self: Notifier block.
61 * @cmd: CPU PM event.
62 * @v: Private data (unused).
63 *
64 * This is called when a CPU power management event occurs, and is used to
65 * ensure that important CPU context is preserved across a CPU power down.
66 */
67 static int mips_pm_notifier(struct notifier_block *self, unsigned long cmd,
68 void *v)
69 {
70 int ret;
71
72 switch (cmd) {
73 case CPU_PM_ENTER:
74 ret = mips_cpu_save();
75 if (ret)
76 return NOTIFY_STOP;
77 break;
78 case CPU_PM_ENTER_FAILED:
79 case CPU_PM_EXIT:
80 mips_cpu_restore();
81 break;
82 }
83
84 return NOTIFY_OK;
85 }
86
87 static struct notifier_block mips_pm_notifier_block = {
88 .notifier_call = mips_pm_notifier,
89 };
90
91 static int __init mips_pm_init(void)
92 {
93 return cpu_pm_register_notifier(&mips_pm_notifier_block);
94 }
95 arch_initcall(mips_pm_init);
96
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