cpufreq: Rank modules and choose the best one

headers/os/drivers/cpufreq.h

@@ -17,6 +17,8 @@ const int kCPUPerformanceScaleMax = 1000;
 typedef struct cpufreq_module_info {
 	module_info		info;
 
+	float			rank;
+
 	status_t		(*increase_performance)(int delta, bool allowBoost);
 	status_t		(*decrease_performance)(int delta);
 } cpufreq_module_info;

src/add-ons/kernel/power/cpufreq/intel_pstates/intel_pstates.cpp

@@ -222,6 +222,8 @@ static cpufreq_module_info sIntelPStates = {
 		std_ops,
 	},
 
+	1.0f,
+
 	increase_performance,
 	decrease_performance,
 };

src/system/kernel/cpu.cpp

@@ -63,13 +63,22 @@ load_cpufreq_module()
 	while (true) {
 		char name[B_FILE_NAME_LENGTH];
 		size_t nameLength = sizeof(name);
+		cpufreq_module_info* current = NULL;
 
 		if (read_next_module_name(cookie, name, &nameLength) != B_OK)
 			break;
 
-		if (get_module(name, (module_info**)&sCPUPerformanceModule) == B_OK) {
+		if (get_module(name, (module_info**)&current) == B_OK) {
 			dprintf("found cpufreq module: %s\n", name);
-			break;
+
+			if (sCPUPerformanceModule != NULL) {
+				if (sCPUPerformanceModule->rank < current->rank) {
+					put_module(sCPUPerformanceModule->info.name);
+					sCPUPerformanceModule = current;
+				} else
+					put_module(name);
+			} else
+				sCPUPerformanceModule = current; 
 		}
 	}