ACPI / processor_idle: introduce ACPI_PROCESSOR_CSTATE

ACPI 6.0 adds a new method to specify the CPU idle states(C-states)
called Low Power Idle(LPI) states. Since new architectures like ARM64
use only LPIs, introduce ACPI_PROCESSOR_CSTATE to encapsulate all the
code supporting the old style C-states(_CST).

This patch will help to extend the processor_idle module to support
LPI.

Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

3 files changed, 58 insertions, 28 deletions

diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig
index b7e2e776397d..1358fb7d7a68 100644
--- a/drivers/acpi/Kconfig
+++ b/drivers/acpi/Kconfig
@@ -213,6 +213,10 @@ config ACPI_CPU_FREQ_PSS
         bool
         select THERMAL
 
+config ACPI_PROCESSOR_CSTATE
+        def_bool y
+        depends on IA64 || X86
+
 config ACPI_PROCESSOR_IDLE
         bool
         select CPU_IDLE
diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
index 444e3745c8b3..ca0de35d1c3a 100644
--- a/drivers/acpi/processor_idle.c
+++ b/drivers/acpi/processor_idle.c
@@ -59,6 +59,12 @@ module_param(latency_factor, uint, 0644);
 
 static DEFINE_PER_CPU(struct cpuidle_device *, acpi_cpuidle_device);
 
+struct cpuidle_driver acpi_idle_driver = {
+        .name =         "acpi_idle",
+        .owner =        THIS_MODULE,
+};
+
+#ifdef CONFIG_ACPI_PROCESSOR_CSTATE
 static
 DEFINE_PER_CPU(struct acpi_processor_cx * [CPUIDLE_STATE_MAX], acpi_cstate);
 
@@ -804,11 +810,6 @@ static void acpi_idle_enter_freeze(struct cpuidle_device *dev,
         acpi_idle_do_entry(cx);
 }
 
-struct cpuidle_driver acpi_idle_driver = {
-        .name =         "acpi_idle",
-        .owner =        THIS_MODULE,
-};
-
 /**
  * acpi_processor_setup_cpuidle_cx - prepares and configures CPUIDLE
  * device i.e. per-cpu data
@@ -925,6 +926,50 @@ static int acpi_processor_setup_cpuidle_states(struct acpi_processor *pr)
         return 0;
 }
 
+static inline void acpi_processor_cstate_first_run_checks(void)
+{
+        acpi_status status;
+        static int first_run;
+
+        if (first_run)
+                return;
+        dmi_check_system(processor_power_dmi_table);
+        max_cstate = acpi_processor_cstate_check(max_cstate);
+        if (max_cstate < ACPI_C_STATES_MAX)
+                pr_notice("ACPI: processor limited to max C-state %d\n",
+                          max_cstate);
+        first_run++;
+
+        if (acpi_gbl_FADT.cst_control && !nocst) {
+                status = acpi_os_write_port(acpi_gbl_FADT.smi_command,
+                                            acpi_gbl_FADT.cst_control, 8);
+                if (ACPI_FAILURE(status))
+                        ACPI_EXCEPTION((AE_INFO, status,
+                                        "Notifying BIOS of _CST ability failed"));
+        }
+}
+#else
+
+static inline int disabled_by_idle_boot_param(void) { return 0; }
+static inline void acpi_processor_cstate_first_run_checks(void) { }
+static int acpi_processor_get_power_info(struct acpi_processor *pr)
+{
+        return -ENODEV;
+}
+
+static int acpi_processor_setup_cpuidle_cx(struct acpi_processor *pr,
+                                           struct cpuidle_device *dev)
+{
+        return -EINVAL;
+}
+
+static int acpi_processor_setup_cpuidle_states(struct acpi_processor *pr)
+{
+        return -EINVAL;
+}
+
+#endif /* CONFIG_ACPI_PROCESSOR_CSTATE */
+
 int acpi_processor_hotplug(struct acpi_processor *pr)
 {
         int ret = 0;
@@ -1015,35 +1060,16 @@ static int acpi_processor_registered;
 
 int acpi_processor_power_init(struct acpi_processor *pr)
 {
-        acpi_status status;
         int retval;
         struct cpuidle_device *dev;
-        static int first_run;
 
         if (disabled_by_idle_boot_param())
                 return 0;
 
-        if (!first_run) {
-                dmi_check_system(processor_power_dmi_table);
-                max_cstate = acpi_processor_cstate_check(max_cstate);
-                if (max_cstate < ACPI_C_STATES_MAX)
-                        printk(KERN_NOTICE
-                               "ACPI: processor limited to max C-state %d\n",
-                               max_cstate);
-                first_run++;
-        }
+        acpi_processor_cstate_first_run_checks();
 
-        if (acpi_gbl_FADT.cst_control && !nocst) {
-                status =
-                    acpi_os_write_port(acpi_gbl_FADT.smi_command, acpi_gbl_FADT.cst_control, 8);
-                if (ACPI_FAILURE(status)) {
-                        ACPI_EXCEPTION((AE_INFO, status,
-                                        "Notifying BIOS of _CST ability failed"));
-                }
-        }
-
-        acpi_processor_get_power_info(pr);
-        pr->flags.power_setup_done = 1;
+        if (!acpi_processor_get_power_info(pr))
+                pr->flags.power_setup_done = 1;
 
         /*
          * Install the idle handler if processor power management is supported.
diff --git a/include/acpi/processor.h b/include/acpi/processor.h
index 6f1805dd5d3c..48779d678122 100644
--- a/include/acpi/processor.h
+++ b/include/acpi/processor.h
@@ -242,7 +242,7 @@ extern int acpi_processor_get_performance_info(struct acpi_processor *pr);
 DECLARE_PER_CPU(struct acpi_processor *, processors);
 extern struct acpi_processor_errata errata;
 
-#ifdef ARCH_HAS_POWER_INIT
+#if defined(ARCH_HAS_POWER_INIT) && defined(CONFIG_ACPI_PROCESSOR_CSTATE)
 void acpi_processor_power_init_bm_check(struct acpi_processor_flags *flags,
                                         unsigned int cpu);
 int acpi_processor_ffh_cstate_probe(unsigned int cpu,