arch/arm64/kernel/suspend.c

   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 phys_addr_t sleep_aee_rec_cpu_dormant_va;
  13
  14 #define pclog()                                                         \
  15         do {                                                            \
  16                 __asm__ __volatile__  (                                 \
  17                         "mrs    x7, mpidr_el1 \n\t"                     \
  18                         "ubfx   x8, x7, #0, #8 \n\t"                    \
  19                         "ubfx   x9, x7, #8, #8 \n\t"                    \
  20                         "add    x8, x8, x9, lsl #2 \n\t"                \
  21                         "ldr    x9, =sleep_aee_rec_cpu_dormant_va \n\t" \
  22                         "ldr    x9, [x9] \n\t"                          \
  23                         "cbz    x9, 1f \n\t"                            \
  24                         "adr    x10, 1f \n\t"                           \
  25                         "str    x10, [ x9, x8, lsl #3 ] \n\t"           \
  26                         "1: \n\t"                                       \
  27                         ::: "x7", "x8", "x9", "x10");                   \
  28         } while(0)
  29
  30 extern int __cpu_suspend(unsigned long);
  31 /*
  32  * This is called by __cpu_suspend() to save the state, and do whatever
  33  * flushing is required to ensure that when the CPU goes to sleep we have
  34  * the necessary data available when the caches are not searched.
  35  *
  36  * @arg: Argument to pass to suspend operations
  37  * @ptr: CPU context virtual address
  38  * @save_ptr: address of the location where the context physical address
  39  *            must be saved
  40  */
  41 int __cpu_suspend_finisher(unsigned long arg, struct cpu_suspend_ctx *ptr,
  42                            phys_addr_t *save_ptr)
  43 {
  44         int cpu = smp_processor_id();
  45
  46         *save_ptr = virt_to_phys(ptr);
  47
  48         cpu_do_suspend(ptr);
  49         /*
  50          * Only flush the context that must be retrieved with the MMU
  51          * off. VA primitives ensure the flush is applied to all
  52          * cache levels so context is pushed to DRAM.
  53          */
  54         __flush_dcache_area(ptr, sizeof(*ptr));
  55         __flush_dcache_area(save_ptr, sizeof(*save_ptr));
  56
  57         return cpu_ops[cpu]->cpu_suspend(arg);
  58 }
  59
  60 /*
  61  * This hook is provided so that cpu_suspend code can restore HW
  62  * breakpoints as early as possible in the resume path, before reenabling
  63  * debug exceptions. Code cannot be run from a CPU PM notifier since by the
  64  * time the notifier runs debug exceptions might have been enabled already,
  65  * with HW breakpoints registers content still in an unknown state.
  66  */
  67 void (*hw_breakpoint_restore)(void *);
  68 void __init cpu_suspend_set_dbg_restorer(void (*hw_bp_restore)(void *))
  69 {
  70         /* Prevent multiple restore hook initializations */
  71         if (WARN_ON(hw_breakpoint_restore))
  72                 return;
  73         hw_breakpoint_restore = hw_bp_restore;
  74 }
  75
  76 /**
  77  * cpu_suspend
  78  *
  79  * @arg: argument to pass to the finisher function
  80  */
  81 int cpu_suspend(unsigned long arg)
  82 {
  83         struct mm_struct *mm = current->active_mm;
  84         int ret, cpu = smp_processor_id();
  85         unsigned long flags;
  86
  87         /*
  88          * If cpu_ops have not been registered or suspend
  89          * has not been initialized, cpu_suspend call fails early.
  90          */
  91         if (!cpu_ops[cpu] || !cpu_ops[cpu]->cpu_suspend)
  92                 return -EOPNOTSUPP;
  93
  94         /*
  95          * From this point debug exceptions are disabled to prevent
  96          * updates to mdscr register (saved and restored along with
  97          * general purpose registers) from kernel debuggers.
  98          */
  99         local_dbg_save(flags);
 100
 101         /*
 102          * mm context saved on the stack, it will be restored when
 103          * the cpu comes out of reset through the identity mapped
 104          * page tables, so that the thread address space is properly
 105          * set-up on function return.
 106          */
 107         ret = __cpu_suspend(arg);
 108         pclog();
 109
 110         if (ret == 0) {
 111                 cpu_switch_mm(mm->pgd, mm);
 112                 flush_tlb_all();
 113
 114                 /*
 115                  * Restore per-cpu offset before any kernel
 116                  * subsystem relying on it has a chance to run.
 117                  */
 118                 set_my_cpu_offset(per_cpu_offset(cpu));
 119
 120                 /*
 121                  * Restore HW breakpoint registers to sane values
 122                  * before debug exceptions are possibly reenabled
 123                  * through local_dbg_restore.
 124                  */
 125                 if (hw_breakpoint_restore)
 126                         hw_breakpoint_restore(NULL);
 127         }
 128
 129         /*
 130          * Restore pstate flags. OS lock and mdscr have been already
 131          * restored, so from this point onwards, debugging is fully
 132          * renabled if it was enabled when core started shutdown.
 133          */
 134         local_dbg_restore(flags);
 135
 136         return ret;
 137 }
 138
 139 extern struct sleep_save_sp sleep_save_sp;
 140 extern phys_addr_t sleep_idmap_phys;
 141
 142 static int cpu_suspend_init(void)
 143 {
 144         void *ctx_ptr;
 145
 146         /* ctx_ptr is an array of physical addresses */
 147         ctx_ptr = kcalloc(mpidr_hash_size(), sizeof(phys_addr_t), GFP_KERNEL);
 148
 149         if (WARN_ON(!ctx_ptr))
 150                 return -ENOMEM;
 151
 152         sleep_save_sp.save_ptr_stash = ctx_ptr;
 153         sleep_save_sp.save_ptr_stash_phys = virt_to_phys(ctx_ptr);
 154         sleep_idmap_phys = virt_to_phys(idmap_pg_dir);
 155         __flush_dcache_area(&sleep_save_sp, sizeof(struct sleep_save_sp));
 156         __flush_dcache_area(&sleep_idmap_phys, sizeof(sleep_idmap_phys));
 157
 158         return 0;
 159 }
 160 early_initcall(cpu_suspend_init);