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> 12 13 extern int __cpu_suspend_enter(unsigned long arg, int (*fn)(unsigned long)); 14 /* 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. 18 * 19 * ptr: CPU context virtual address 20 * save_ptr: address of the location where the context physical address 21 * must be saved 22 */ 23 void notrace __cpu_suspend_save(struct cpu_suspend_ctx *ptr, 24 phys_addr_t *save_ptr) 25 { 26 *save_ptr = virt_to_phys(ptr); 27 28 cpu_do_suspend(ptr); 29 /* 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. 33 */ 34 __flush_dcache_area(ptr, sizeof(*ptr)); 35 __flush_dcache_area(save_ptr, sizeof(*save_ptr)); 36 } 37 38 /* 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. 44 */ 45 void (*hw_breakpoint_restore)(void *); 46 void __init cpu_suspend_set_dbg_restorer(void (*hw_bp_restore)(void *)) 47 { 48 /* Prevent multiple restore hook initializations */ 49 if (WARN_ON(hw_breakpoint_restore)) 50 return; 51 hw_breakpoint_restore = hw_bp_restore; 52 } 53 54 /** 55 * cpu_suspend() - function to enter a low-power state 56 * @arg: argument to pass to CPU suspend operations 57 * 58 * Return: 0 on success, -EOPNOTSUPP if CPU suspend hook not initialized, CPU 59 * operations back-end error code otherwise. 60 */ 61 int cpu_suspend(unsigned long arg) 62 { 63 int cpu = smp_processor_id(); 64 65 /* 66 * If cpu_ops have not been registered or suspend 67 * has not been initialized, cpu_suspend call fails early. 68 */ 69 if (!cpu_ops[cpu] || !cpu_ops[cpu]->cpu_suspend) 70 return -EOPNOTSUPP; 71 return cpu_ops[cpu]->cpu_suspend(arg); 72 } 73 74 /* 75 * __cpu_suspend 76 * 77 * arg: argument to pass to the finisher function 78 * fn: finisher function pointer 79 * 80 */ 81 int __cpu_suspend(unsigned long arg, int (*fn)(unsigned long)) 82 { 83 struct mm_struct *mm = current->active_mm; 84 int ret; 85 unsigned long flags; 86 87 /* 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. 91 */ 92 local_dbg_save(flags); 93 94 /* 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. 99 */ 100 ret = __cpu_suspend_enter(arg, fn); 101 if (ret == 0) { 102 /* 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. 108 */ 109 if (mm == &init_mm) 110 cpu_set_reserved_ttbr0(); 111 else 112 cpu_switch_mm(mm->pgd, mm); 113 114 flush_tlb_all(); 115 116 /* 117 * Restore per-cpu offset before any kernel 118 * subsystem relying on it has a chance to run. 119 */ 120 set_my_cpu_offset(per_cpu_offset(smp_processor_id())); 121 122 /* 123 * Restore HW breakpoint registers to sane values 124 * before debug exceptions are possibly reenabled 125 * through local_dbg_restore. 126 */ 127 if (hw_breakpoint_restore) 128 hw_breakpoint_restore(NULL); 129 } 130 131 /* 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. 135 */ 136 local_dbg_restore(flags); 137 138 return ret; 139 } 140 141 struct sleep_save_sp sleep_save_sp; 142 phys_addr_t sleep_idmap_phys; 143 144 static int __init cpu_suspend_init(void) 145 { 146 void *ctx_ptr; 147 148 /* ctx_ptr is an array of physical addresses */ 149 ctx_ptr = kcalloc(mpidr_hash_size(), sizeof(phys_addr_t), GFP_KERNEL); 150 151 if (WARN_ON(!ctx_ptr)) 152 return -ENOMEM; 153 154 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)); 159 160 return 0; 161 } 162 early_initcall(cpu_suspend_init); 163