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authorAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-08-05 17:04:01 -0300
committerAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-08-05 17:04:01 -0300
commit57f0f512b273f60d52568b8c6b77e17f5636edc0 (patch)
tree5e910f0e82173f4ef4f51111366a3f1299037a7b /arch/arm64/kernel/suspend.c
Initial import
Diffstat (limited to 'arch/arm64/kernel/suspend.c')
-rw-r--r--arch/arm64/kernel/suspend.c141
1 files changed, 141 insertions, 0 deletions
diff --git a/arch/arm64/kernel/suspend.c b/arch/arm64/kernel/suspend.c
new file mode 100644
index 000000000..d7daf45ae
--- /dev/null
+++ b/arch/arm64/kernel/suspend.c
@@ -0,0 +1,141 @@
+#include <linux/percpu.h>
+#include <linux/slab.h>
+#include <asm/cacheflush.h>
+#include <asm/debug-monitors.h>
+#include <asm/pgtable.h>
+#include <asm/memory.h>
+#include <asm/mmu_context.h>
+#include <asm/smp_plat.h>
+#include <asm/suspend.h>
+#include <asm/tlbflush.h>
+
+extern int __cpu_suspend_enter(unsigned long arg, int (*fn)(unsigned long));
+/*
+ * This is called by __cpu_suspend_enter() to save the state, and do whatever
+ * flushing is required to ensure that when the CPU goes to sleep we have
+ * the necessary data available when the caches are not searched.
+ *
+ * ptr: CPU context virtual address
+ * save_ptr: address of the location where the context physical address
+ * must be saved
+ */
+void notrace __cpu_suspend_save(struct cpu_suspend_ctx *ptr,
+ phys_addr_t *save_ptr)
+{
+ *save_ptr = virt_to_phys(ptr);
+
+ cpu_do_suspend(ptr);
+ /*
+ * Only flush the context that must be retrieved with the MMU
+ * off. VA primitives ensure the flush is applied to all
+ * cache levels so context is pushed to DRAM.
+ */
+ __flush_dcache_area(ptr, sizeof(*ptr));
+ __flush_dcache_area(save_ptr, sizeof(*save_ptr));
+}
+
+/*
+ * This hook is provided so that cpu_suspend code can restore HW
+ * breakpoints as early as possible in the resume path, before reenabling
+ * debug exceptions. Code cannot be run from a CPU PM notifier since by the
+ * time the notifier runs debug exceptions might have been enabled already,
+ * with HW breakpoints registers content still in an unknown state.
+ */
+void (*hw_breakpoint_restore)(void *);
+void __init cpu_suspend_set_dbg_restorer(void (*hw_bp_restore)(void *))
+{
+ /* Prevent multiple restore hook initializations */
+ if (WARN_ON(hw_breakpoint_restore))
+ return;
+ hw_breakpoint_restore = hw_bp_restore;
+}
+
+/*
+ * __cpu_suspend
+ *
+ * arg: argument to pass to the finisher function
+ * fn: finisher function pointer
+ *
+ */
+int __cpu_suspend(unsigned long arg, int (*fn)(unsigned long))
+{
+ struct mm_struct *mm = current->active_mm;
+ int ret;
+ unsigned long flags;
+
+ /*
+ * From this point debug exceptions are disabled to prevent
+ * updates to mdscr register (saved and restored along with
+ * general purpose registers) from kernel debuggers.
+ */
+ local_dbg_save(flags);
+
+ /*
+ * mm context saved on the stack, it will be restored when
+ * the cpu comes out of reset through the identity mapped
+ * page tables, so that the thread address space is properly
+ * set-up on function return.
+ */
+ ret = __cpu_suspend_enter(arg, fn);
+ if (ret == 0) {
+ /*
+ * We are resuming from reset with TTBR0_EL1 set to the
+ * idmap to enable the MMU; restore the active_mm mappings in
+ * TTBR0_EL1 unless the active_mm == &init_mm, in which case
+ * the thread entered __cpu_suspend with TTBR0_EL1 set to
+ * reserved TTBR0 page tables and should be restored as such.
+ */
+ if (mm == &init_mm)
+ cpu_set_reserved_ttbr0();
+ else
+ cpu_switch_mm(mm->pgd, mm);
+
+ flush_tlb_all();
+
+ /*
+ * Restore per-cpu offset before any kernel
+ * subsystem relying on it has a chance to run.
+ */
+ set_my_cpu_offset(per_cpu_offset(smp_processor_id()));
+
+ /*
+ * Restore HW breakpoint registers to sane values
+ * before debug exceptions are possibly reenabled
+ * through local_dbg_restore.
+ */
+ if (hw_breakpoint_restore)
+ hw_breakpoint_restore(NULL);
+ }
+
+ /*
+ * Restore pstate flags. OS lock and mdscr have been already
+ * restored, so from this point onwards, debugging is fully
+ * renabled if it was enabled when core started shutdown.
+ */
+ local_dbg_restore(flags);
+
+ return ret;
+}
+
+struct sleep_save_sp sleep_save_sp;
+phys_addr_t sleep_idmap_phys;
+
+static int __init cpu_suspend_init(void)
+{
+ void *ctx_ptr;
+
+ /* ctx_ptr is an array of physical addresses */
+ ctx_ptr = kcalloc(mpidr_hash_size(), sizeof(phys_addr_t), GFP_KERNEL);
+
+ if (WARN_ON(!ctx_ptr))
+ return -ENOMEM;
+
+ sleep_save_sp.save_ptr_stash = ctx_ptr;
+ sleep_save_sp.save_ptr_stash_phys = virt_to_phys(ctx_ptr);
+ sleep_idmap_phys = virt_to_phys(idmap_pg_dir);
+ __flush_dcache_area(&sleep_save_sp, sizeof(struct sleep_save_sp));
+ __flush_dcache_area(&sleep_idmap_phys, sizeof(sleep_idmap_phys));
+
+ return 0;
+}
+early_initcall(cpu_suspend_init);