ACPI: cpufreq: Add highest perf change notification

Platform firmware sends notify 0x85 to inform the OS that the highest
performance of a CPU has changed.

This will be used by the AMD P-state driver to update the ranking of
preferred cores and set the priority of cores accordingly.

Tested-by: Oleksandr Natalenko <[e-mail]>
Reviewed-by: Mario Limonciello <[e-mail]>
Reviewed-by: Huang Rui <[e-mail]>
Reviewed-by: Perry Yuan <[e-mail]>
Signed-off-by: Meng Li <[e-mail]>
Link: https://uefi.org/specs/ACPI/6.5/05_ACPI_Software_Programming_Model.html#processor-device-notification-values
[ rjw: New subject, changelog edits ]
Signed-off-by: Rafael J. Wysocki <[e-mail]>

drivers/acpi/processor_driver.c

···
 #define ACPI_PROCESSOR_NOTIFY_PERFORMANCE 0x80
 #define ACPI_PROCESSOR_NOTIFY_POWER	0x81
 #define ACPI_PROCESSOR_NOTIFY_THROTTLING	0x82
+#define ACPI_PROCESSOR_NOTIFY_HIGEST_PERF_CHANGED	0x85
 
 MODULE_AUTHOR("Paul Diefenbaugh");
 MODULE_DESCRIPTION("ACPI Processor Driver");
···
 		break;
 	case ACPI_PROCESSOR_NOTIFY_THROTTLING:
 		acpi_processor_tstate_has_changed(pr);
+		acpi_bus_generate_netlink_event(device->pnp.device_class,
+						  dev_name(&device->dev), event, 0);
+		break;
+	case ACPI_PROCESSOR_NOTIFY_HIGEST_PERF_CHANGED:
+		cpufreq_update_limits(pr->id);
 		acpi_bus_generate_netlink_event(device->pnp.device_class,
 						  dev_name(&device->dev), event, 0);
 		break;

include/linux/cpufreq.h

···
 	return false;
 }
 static inline void disable_cpufreq(void) { }
+static inline void cpufreq_update_limits(unsigned int cpu) { }
 #endif
 
 #ifdef CONFIG_CPU_FREQ_STAT