From a300a5681a40b9cc7f2b9a651f3c159e90a7753b Mon Sep 17 00:00:00 2001
From: Jeremy Soller <jeremy@system76.com>
Date: Tue, 1 Oct 2019 12:01:46 -0600
Subject: [PATCH] Attempt to initialize PWM for CPU fan

---
 src/board/system76/galp3-c/pwm.c | 24 ++++++++++++++++++++++--
 1 file changed, 22 insertions(+), 2 deletions(-)

diff --git a/src/board/system76/galp3-c/pwm.c b/src/board/system76/galp3-c/pwm.c
index 3a66f2a..4b97649 100644
--- a/src/board/system76/galp3-c/pwm.c
+++ b/src/board/system76/galp3-c/pwm.c
@@ -3,6 +3,26 @@
 void pwm_init(void) {
     // Set T0CHSEL to TACH0A and T1CHSEL to TACH1A
     TSWCTLR = 0;
-    // Turn on the CPU fan at full blast (temperature control TODO)
-    DCR2 = 0xFF;
+
+    // Disable PWM
+    ZTIER = 0;
+
+    // Set prescaler to 1159 + 1
+    C6CPRS = 0x87;
+    C6MCPRS = 0x04;
+
+    // Set cycle time to 255 + 1
+    CTR2 = 0xFF;
+
+    // Turn on the CPU fan at half blast (temperature control TODO)
+    DCR2 = 0x80;
+
+    // Set gating clock source
+    PCSGR = 0xFF;
+
+    // Set PWM2 output to use C6CPRS / CTR2
+    PCSSGL = (0b10 << 4);
+
+    // Enable PWM
+    ZTIER = (1 << 1);
 }