idle, x86: Allow off-lined CPU to enter deeper C states

Currently when a CPU is off-lined it enters either MWAIT-based idle or,
if MWAIT is not desired or supported, HLT-based idle (which places the
processor in C1 state). This patch allows processors without MWAIT
support to stay in states deeper than C1.

Signed-off-by: Boris Ostrovsky <boris.ostrovsky@amd.com>
Signed-off-by: Len Brown <len.brown@intel.com>

1 files changed, 31 insertions, 0 deletions

diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
index 0e8e2de2ed3e..6b1d32a161ae 100644
--- a/drivers/acpi/processor_idle.c
+++ b/drivers/acpi/processor_idle.c
@@ -770,6 +770,35 @@ static int acpi_idle_enter_c1(struct cpuidle_device *dev,
         return index;
 }
 
+
+/**
+ * acpi_idle_play_dead - enters an ACPI state for long-term idle (i.e. off-lining)
+ * @dev: the target CPU
+ * @index: the index of suggested state
+ */
+static int acpi_idle_play_dead(struct cpuidle_device *dev, int index)
+{
+        struct cpuidle_state_usage *state_usage = &dev->states_usage[index];
+        struct acpi_processor_cx *cx = cpuidle_get_statedata(state_usage);
+
+        ACPI_FLUSH_CPU_CACHE();
+
+        while (1) {
+
+                if (cx->entry_method == ACPI_CSTATE_HALT)
+                        halt();
+                else if (cx->entry_method == ACPI_CSTATE_SYSTEMIO) {
+                        inb(cx->address);
+                        /* See comment in acpi_idle_do_entry() */
+                        inl(acpi_gbl_FADT.xpm_timer_block.address);
+                } else
+                        return -ENODEV;
+        }
+
+        /* Never reached */
+        return 0;
+}
+
 /**
  * acpi_idle_enter_simple - enters an ACPI state without BM handling
  * @dev: the target CPU
@@ -1077,12 +1106,14 @@ static int acpi_processor_setup_cpuidle_states(struct acpi_processor *pr)
                                 state->flags |= CPUIDLE_FLAG_TIME_VALID;
 
                         state->enter = acpi_idle_enter_c1;
+                        state->enter_dead = acpi_idle_play_dead;
                         drv->safe_state_index = count;
                         break;
 
                         case ACPI_STATE_C2:
                         state->flags |= CPUIDLE_FLAG_TIME_VALID;
                         state->enter = acpi_idle_enter_simple;
+                        state->enter_dead = acpi_idle_play_dead;
                         drv->safe_state_index = count;
                         break;