soc/intel/apollolake: Make usage of RAPL selectable

Apollo Lake SoC supports configuration of Running Average Power Limits
(RAPL) for package domain. This feature is not required for all APL
mainboards. According to the APL SoC EDS Vol 4 chapter 18.4 Power
Limiting Control it is not necessary to enable the RAPL algorithm per
default. For that reason make the RAPL configuration selectable.

Change-Id: Ib737b162f72b76c15e5768859f9099e2e7ef6426
Signed-off-by: Mario Scheithauer <mario.scheithauer@siemens.com>
Reviewed-on: https://review.coreboot.org/20759
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>

src/soc/intel/apollolake/Kconfig

@@ -342,4 +342,12 @@ config CPU_BCLK_MHZ
 	int
 	default 100
 
+config APL_SKIP_SET_POWER_LIMITS
+	bool
+	default n
+	help
+	  Some Apollo Lake mainboards do not need the Running Average Power
+	  Limits (RAPL) algorithm for a constant power management.
+	  Set this config option to skip the RAPL configuration.
+
 endif

src/soc/intel/apollolake/chip.c

@@ -223,6 +223,11 @@ static void set_power_limits(void)
 	uint32_t tdp, min_power, max_power;
 	uint32_t pl2_val;
 
+	if (IS_ENABLED(CONFIG_APL_SKIP_SET_POWER_LIMITS)) {
+		printk(BIOS_INFO, "Skip the RAPL settings.\n");
+		return;
+	}
+
 	if (!dev || !dev->chip_info) {
 		printk(BIOS_ERR, "BUG! Could not find SOC devicetree config\n");
 		return;