ec/system76/ec: Add config for 2nd fan without dGPU

The darp10 has a second fan but no dGPU. The NFAN Method must exist, so
use the default hwmon names of "fan1" and "fan2" for labels.

Change-Id: Icde5dec82262d9262b046c1557167801af8e5cb2
Signed-off-by: Tim Crawford <tcrawford@system76.com>

Author: crawfxrd

src/ec/system76/ec/Kconfig

@@ -6,21 +6,27 @@ config EC_SYSTEM76_EC
 	  System76 EC
 
 config EC_SYSTEM76_EC_BAT_THRESHOLDS
-	depends on EC_SYSTEM76_EC
 	bool
 	default y
+	depends on EC_SYSTEM76_EC
 
-config EC_SYSTEM76_EC_DGPU
+config EC_SYSTEM76_EC_FAN2
+	bool
+	default n
 	depends on EC_SYSTEM76_EC
+
+config EC_SYSTEM76_EC_DGPU
 	bool
 	default n
+	select EC_SYSTEM76_EC_FAN2
+	depends on EC_SYSTEM76_EC
 
 config EC_SYSTEM76_EC_LOCKDOWN
-	depends on EC_SYSTEM76_EC
 	bool
 	default n
+	depends on EC_SYSTEM76_EC
 
 config EC_SYSTEM76_EC_OLED
-	depends on EC_SYSTEM76_EC
 	bool
 	default n
+	depends on EC_SYSTEM76_EC

src/ec/system76/ec/acpi/s76.asl

@@ -126,9 +126,14 @@ Device (S76D) {
 	// Fan names
 	Method (NFAN, 0, Serialized) {
 		Return (Package() {
-			"CPU fan",
 #if CONFIG(EC_SYSTEM76_EC_DGPU)
+			"CPU fan",
 			"GPU fan",
+#elif CONFIG(EC_SYSTEM76_EC_FAN2)
+			"fan1",
+			"fan2",
+#else
+			"CPU fan",
 #endif
 		})
 	}

src/mainboard/system76/mtl/Kconfig

@@ -28,12 +28,14 @@ config BOARD_SYSTEM76_MTL_COMMON
 
 config BOARD_SYSTEM76_DARP10
 	select BOARD_SYSTEM76_MTL_COMMON
+	select EC_SYSTEM76_EC_FAN2
 	select MAINBOARD_USES_IFD_GBE_REGION
 	select SOC_INTEL_ENABLE_USB4_PCIE_RESOURCES
 	select SOC_INTEL_METEORLAKE_U_H
 
 config BOARD_SYSTEM76_DARP10_B
 	select BOARD_SYSTEM76_MTL_COMMON
+	select EC_SYSTEM76_EC_FAN2
 	select MAINBOARD_USES_IFD_GBE_REGION
 	select SOC_INTEL_ENABLE_USB4_PCIE_RESOURCES
 	select SOC_INTEL_METEORLAKE_U_H