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/smp_plat.h> 9 #include <asm/suspend.h> 10 #include <asm/tlbflush.h> 11 12 extern int __cpu_suspend_enter(unsigned long arg, int (*fn)(unsigned long)); 13 /* 14 * This is called by __cpu_suspend_enter() to save the state, and do whatever 15 * flushing is required to ensure that when the CPU goes to sleep we have 16 * the necessary data available when the caches are not searched. 17 * 18 * ptr: CPU context virtual address 19 * save_ptr: address of the location where the context physical address 20 * must be saved 21 */ 22 void notrace __cpu_suspend_save(struct cpu_suspend_ctx *ptr, 23 phys_addr_t *save_ptr) 24 { 25 *save_ptr = virt_to_phys(ptr); 26 27 cpu_do_suspend(ptr); 28 /* 29 * Only flush the context that must be retrieved with the MMU 30 * off. VA primitives ensure the flush is applied to all 31 * cache levels so context is pushed to DRAM. 32 */ 33 __flush_dcache_area(ptr, sizeof(*ptr)); 34 __flush_dcache_area(save_ptr, sizeof(*save_ptr)); 35 } 36 37 /* 38 * This hook is provided so that cpu_suspend code can restore HW 39 * breakpoints as early as possible in the resume path, before reenabling 40 * debug exceptions. Code cannot be run from a CPU PM notifier since by the 41 * time the notifier runs debug exceptions might have been enabled already, 42 * with HW breakpoints registers content still in an unknown state. 43 */ 44 void (*hw_breakpoint_restore)(void *); 45 void __init cpu_suspend_set_dbg_restorer(void (*hw_bp_restore)(void *)) 46 { 47 /* Prevent multiple restore hook initializations */ 48 if (WARN_ON(hw_breakpoint_restore)) 49 return; 50 hw_breakpoint_restore = hw_bp_restore; 51 } 52 53 /** 54 * cpu_suspend() - function to enter a low-power state 55 * @arg: argument to pass to CPU suspend operations 56 * 57 * Return: 0 on success, -EOPNOTSUPP if CPU suspend hook not initialized, CPU 58 * operations back-end error code otherwise. 59 */ 60 int cpu_suspend(unsigned long arg) 61 { 62 int cpu = smp_processor_id(); 63 64 /* 65 * If cpu_ops have not been registered or suspend 66 * has not been initialized, cpu_suspend call fails early. 67 */ 68 if (!cpu_ops[cpu] || !cpu_ops[cpu]->cpu_suspend) 69 return -EOPNOTSUPP; 70 return cpu_ops[cpu]->cpu_suspend(arg); 71 } 72 73 /* 74 * __cpu_suspend 75 * 76 * arg: argument to pass to the finisher function 77 * fn: finisher function pointer 78 * 79 */ 80 int __cpu_suspend(unsigned long arg, int (*fn)(unsigned long)) 81 { 82 struct mm_struct *mm = current->active_mm; 83 int ret; 84 unsigned long flags; 85 86 /* 87 * From this point debug exceptions are disabled to prevent 88 * updates to mdscr register (saved and restored along with 89 * general purpose registers) from kernel debuggers. 90 */ 91 local_dbg_save(flags); 92 93 /* 94 * mm context saved on the stack, it will be restored when 95 * the cpu comes out of reset through the identity mapped 96 * page tables, so that the thread address space is properly 97 * set-up on function return. 98 */ 99 ret = __cpu_suspend_enter(arg, fn); 100 if (ret == 0) { 101 cpu_switch_mm(mm->pgd, mm); 102 flush_tlb_all(); 103 104 /* 105 * Restore per-cpu offset before any kernel 106 * subsystem relying on it has a chance to run. 107 */ 108 set_my_cpu_offset(per_cpu_offset(smp_processor_id())); 109 110 /* 111 * Restore HW breakpoint registers to sane values 112 * before debug exceptions are possibly reenabled 113 * through local_dbg_restore. 114 */ 115 if (hw_breakpoint_restore) 116 hw_breakpoint_restore(NULL); 117 } 118 119 /* 120 * Restore pstate flags. OS lock and mdscr have been already 121 * restored, so from this point onwards, debugging is fully 122 * renabled if it was enabled when core started shutdown. 123 */ 124 local_dbg_restore(flags); 125 126 return ret; 127 } 128 129 extern struct sleep_save_sp sleep_save_sp; 130 extern phys_addr_t sleep_idmap_phys; 131 132 static int __init cpu_suspend_init(void) 133 { 134 void *ctx_ptr; 135 136 /* ctx_ptr is an array of physical addresses */ 137 ctx_ptr = kcalloc(mpidr_hash_size(), sizeof(phys_addr_t), GFP_KERNEL); 138 139 if (WARN_ON(!ctx_ptr)) 140 return -ENOMEM; 141 142 sleep_save_sp.save_ptr_stash = ctx_ptr; 143 sleep_save_sp.save_ptr_stash_phys = virt_to_phys(ctx_ptr); 144 sleep_idmap_phys = virt_to_phys(idmap_pg_dir); 145 __flush_dcache_area(&sleep_save_sp, sizeof(struct sleep_save_sp)); 146 __flush_dcache_area(&sleep_idmap_phys, sizeof(sleep_idmap_phys)); 147 148 return 0; 149 } 150 early_initcall(cpu_suspend_init); 151