Revert "ACPI: processor: Do not expose global variable acpi_idle_driver"

Revert commit 559f2ea ACPI: processor: Do not expose global variable
acpi_idle_driver" because it depends on a problematic one.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Author: rafaeljw

drivers/acpi/processor_driver.c

@@ -166,7 +166,8 @@ static int __acpi_processor_start(struct acpi_device *device)
 	if (result && !IS_ENABLED(CONFIG_ACPI_CPU_FREQ_PSS))
 		dev_dbg(&device->dev, "CPPC data invalid or not present\n");
 
-	acpi_processor_power_init(pr);
+	if (cpuidle_get_driver() == &acpi_idle_driver)
+		acpi_processor_power_init(pr);
 
 	acpi_pss_perf_init(pr);
 

drivers/acpi/processor_idle.c

@@ -51,7 +51,7 @@ module_param(latency_factor, uint, 0644);
 
 static DEFINE_PER_CPU(struct cpuidle_device *, acpi_cpuidle_device);
 
-static struct cpuidle_driver acpi_idle_driver = {
+struct cpuidle_driver acpi_idle_driver = {
 	.name =		"acpi_idle",
 	.owner =	THIS_MODULE,
 };
@@ -1404,13 +1404,6 @@ void acpi_processor_power_init(struct acpi_processor *pr)
 {
 	struct cpuidle_device *dev;
 
-	/*
-	 * The code below only works if the current cpuidle driver is the ACPI
-	 * idle driver.
-	 */
-	if (cpuidle_get_driver() != &acpi_idle_driver)
-		return;
-
 	if (disabled_by_idle_boot_param())
 		return;
 

include/acpi/processor.h

@@ -417,6 +417,7 @@ static inline void acpi_processor_throttling_init(void) {}
 #endif	/* CONFIG_ACPI_CPU_FREQ_PSS */
 
 /* in processor_idle.c */
+extern struct cpuidle_driver acpi_idle_driver;
 #ifdef CONFIG_ACPI_PROCESSOR_IDLE
 void acpi_processor_power_init(struct acpi_processor *pr);
 void acpi_processor_power_exit(struct acpi_processor *pr);