From 017c03c9a35bd97b9cff1f1a9cbdbff2ca239cc8 Mon Sep 17 00:00:00 2001
From: Tim Crawford <tcrawford@system76.com>
Date: Tue, 4 Feb 2025 13:30:10 -0700
Subject: [PATCH] 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 <tcrawford@system76.com>
---
 src/ec/system76/ec/acpi/ec_ram.asl |  1 +
 src/ec/system76/ec/acpi/s76.asl    | 58 +++++++++++++++++++++++++++++-
 2 files changed, 58 insertions(+), 1 deletion(-)

diff --git a/src/ec/system76/ec/acpi/ec_ram.asl b/src/ec/system76/ec/acpi/ec_ram.asl
index cb5bcf14441..e41fc9a98da 100644
--- a/src/ec/system76/ec/acpi/ec_ram.asl
+++ b/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
diff --git a/src/ec/system76/ec/acpi/s76.asl b/src/ec/system76/ec/acpi/s76.asl
index f3e2deccdff..84e50011bca 100644
--- a/src/ec/system76/ec/acpi/s76.asl
+++ b/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
+				}
+			}
+		}
+	}
 }