1 #include <linux/percpu.h>
2 #include <linux/slab.h>
3 #include <asm/cacheflush.h>
4 #include <asm/cpu_ops.h>
5 #include <asm/debug-monitors.h>
6 #include <asm/pgtable.h>
7 #include <asm/memory.h>
8 #include <asm/mmu_context.h>
9 #include <asm/smp_plat.h>
10 #include <asm/suspend.h>
11 #include <asm/tlbflush.h>
13 extern int __cpu_suspend_enter(unsigned long arg, int (*fn)(unsigned long));
15 * This is called by __cpu_suspend_enter() to save the state, and do whatever
16 * flushing is required to ensure that when the CPU goes to sleep we have
17 * the necessary data available when the caches are not searched.
19 * ptr: CPU context virtual address
20 * save_ptr: address of the location where the context physical address
23 void notrace __cpu_suspend_save(struct cpu_suspend_ctx *ptr,
24 phys_addr_t *save_ptr)
26 *save_ptr = virt_to_phys(ptr);
30 * Only flush the context that must be retrieved with the MMU
31 * off. VA primitives ensure the flush is applied to all
32 * cache levels so context is pushed to DRAM.
34 __flush_dcache_area(ptr, sizeof(*ptr));
35 __flush_dcache_area(save_ptr, sizeof(*save_ptr));
39 * This hook is provided so that cpu_suspend code can restore HW
40 * breakpoints as early as possible in the resume path, before reenabling
41 * debug exceptions. Code cannot be run from a CPU PM notifier since by the
42 * time the notifier runs debug exceptions might have been enabled already,
43 * with HW breakpoints registers content still in an unknown state.
45 void (*hw_breakpoint_restore)(void *);
46 void __init cpu_suspend_set_dbg_restorer(void (*hw_bp_restore)(void *))
48 /* Prevent multiple restore hook initializations */
49 if (WARN_ON(hw_breakpoint_restore))
51 hw_breakpoint_restore = hw_bp_restore;
55 * cpu_suspend() - function to enter a low-power state
56 * @arg: argument to pass to CPU suspend operations
58 * Return: 0 on success, -EOPNOTSUPP if CPU suspend hook not initialized, CPU
59 * operations back-end error code otherwise.
61 int cpu_suspend(unsigned long arg)
63 int cpu = smp_processor_id();
66 * If cpu_ops have not been registered or suspend
67 * has not been initialized, cpu_suspend call fails early.
69 if (!cpu_ops[cpu] || !cpu_ops[cpu]->cpu_suspend)
71 return cpu_ops[cpu]->cpu_suspend(arg);
77 * arg: argument to pass to the finisher function
78 * fn: finisher function pointer
81 int __cpu_suspend(unsigned long arg, int (*fn)(unsigned long))
83 struct mm_struct *mm = current->active_mm;
88 * From this point debug exceptions are disabled to prevent
89 * updates to mdscr register (saved and restored along with
90 * general purpose registers) from kernel debuggers.
92 local_dbg_save(flags);
95 * mm context saved on the stack, it will be restored when
96 * the cpu comes out of reset through the identity mapped
97 * page tables, so that the thread address space is properly
98 * set-up on function return.
100 ret = __cpu_suspend_enter(arg, fn);
103 * We are resuming from reset with TTBR0_EL1 set to the
104 * idmap to enable the MMU; restore the active_mm mappings in
105 * TTBR0_EL1 unless the active_mm == &init_mm, in which case
106 * the thread entered __cpu_suspend with TTBR0_EL1 set to
107 * reserved TTBR0 page tables and should be restored as such.
110 cpu_set_reserved_ttbr0();
112 cpu_switch_mm(mm->pgd, mm);
117 * Restore per-cpu offset before any kernel
118 * subsystem relying on it has a chance to run.
120 set_my_cpu_offset(per_cpu_offset(smp_processor_id()));
123 * Restore HW breakpoint registers to sane values
124 * before debug exceptions are possibly reenabled
125 * through local_dbg_restore.
127 if (hw_breakpoint_restore)
128 hw_breakpoint_restore(NULL);
132 * Restore pstate flags. OS lock and mdscr have been already
133 * restored, so from this point onwards, debugging is fully
134 * renabled if it was enabled when core started shutdown.
136 local_dbg_restore(flags);
141 struct sleep_save_sp sleep_save_sp;
142 phys_addr_t sleep_idmap_phys;
144 static int __init cpu_suspend_init(void)
148 /* ctx_ptr is an array of physical addresses */
149 ctx_ptr = kcalloc(mpidr_hash_size(), sizeof(phys_addr_t), GFP_KERNEL);
151 if (WARN_ON(!ctx_ptr))
154 sleep_save_sp.save_ptr_stash = ctx_ptr;
155 sleep_save_sp.save_ptr_stash_phys = virt_to_phys(ctx_ptr);
156 sleep_idmap_phys = virt_to_phys(idmap_pg_dir);
157 __flush_dcache_area(&sleep_save_sp, sizeof(struct sleep_save_sp));
158 __flush_dcache_area(&sleep_idmap_phys, sizeof(sleep_idmap_phys));
162 early_initcall(cpu_suspend_init);