ec/system76/ec: Add manual fan control

system76/ec#512 added a manual fan control option.

In PWM control mode, the system firmware or OS is responsible for
setting the fan target duty to manage thermals. CTR0 in the EC code
determines the maximum valid PWM duty, which is hard-coded to 255.

RPM target is not supported.

Change-Id: Iba8cd5ac540f9fdc20473831787cafb6c1fd8129
Signed-off-by: Tim Crawford <[email protected]>

Author: crawfxrd

src/ec/system76/ec/acpi/ec_ram.asl

@@ -42,6 +42,7 @@ Field (ERAM, ByteAcc, Lock, Preserve)
 	DUT2, 8,	// Fan 2 duty
 	RPM1, 16,	// Fan 1 RPM
 	RPM2, 16,	// Fan 2 RPM
+	FCTL, 8,	// Fan control mode
 	Offset (0xD9),
 	AIRP, 8,	// Airplane mode LED
 	WINF, 8,	// Enable ACPI brightness controls

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

@@ -154,6 +154,32 @@ Device (S76D) {
 		Return ((Local1 << 8) | Local0)
 	}
 
+	// Set fan duty
+	// - Arg0: Fan select
+	// - Arg1: PWM duty (0-255)
+	Method (SFD, 2, Serialized) {
+		If (^^PCI0.LPCB.EC0.ECOK) {
+			// Fail here, but EC will also ignore writes if fan is
+			// set to automatic control.
+			If (^^PCI0.LPCB.EC0.FCTL == 0) {
+				Return (0xFF)
+			}
+
+			If (ToInteger (Arg0) == 0) {
+				^^PCI0.LPCB.EC0.DUT1 = Arg1
+				Return (0x00)
+			}
+#if CONFIG(EC_SYSTEM76_EC_FAN2)
+			If (ToInteger (Arg0) == 1) {
+				^^PCI0.LPCB.EC0.DUT2 = Arg1
+				Return (0x00)
+			}
+#endif
+		}
+
+		Return (0xFF)
+	}
+
 	// Temperature names
 	Method (NTMP, 0, Serialized) {
 		Return (Package() {
@@ -166,7 +192,7 @@ Device (S76D) {
 
 	// Get temperature
 	Method (GTMP, 1, Serialized) {
-		Local0 = 0;
+		Local0 = 0
 		If (^^PCI0.LPCB.EC0.ECOK) {
 			If (Arg0 == 0) {
 				Local0 = ^^PCI0.LPCB.EC0.TMP1
@@ -176,4 +202,34 @@ Device (S76D) {
 		}
 		Return (Local0)
 	}
+
+	// Get fan control mode
+	// - 0: EC automatic control
+	// - 1: Host control via target PWM
+	// - 2: Host control via target RPM
+	Method (GFCM, 0, Serialized) {
+		Local0 = 0xFF
+		If (^^PCI0.LPCB.EC0.ECOK) {
+			Local0 = ^^PCI0.LPCB.EC0.FCTL
+		}
+		Return (Local0)
+	}
+
+	// Set fan control mode
+	// - 0: EC automatic control
+	// - 1: Host control via target PWM
+	// - 2: Host control via target RPM
+	Method (SFCM, 1, Serialized) {
+		If (^^PCI0.LPCB.EC0.ECOK) {
+			Switch (ToInteger (Arg0)) {
+				Case (0x00) {
+					^^PCI0.LPCB.EC0.FCTL = Arg0
+				}
+
+				Case (0x01) {
+					^^PCI0.LPCB.EC0.FCTL = Arg0
+				}
+			}
+		}
+	}
 }