From fc3bad29a2a31555bccaaacb6af6d20b7bb1b7f6 Mon Sep 17 00:00:00 2001
From: Tim Crawford <tcrawford@system76.com>
Date: Mon, 6 May 2024 15:57:54 -0600
Subject: [PATCH] pnp: Match EC2I programming guide

Use the sequence specified by the flowcharts in the ITE manuals.

Ref: IT5570E V0.3.2 datasheet; 7.15.5 EC2I Programming Guide
Signed-off-by: Tim Crawford <tcrawford@system76.com>
---
 src/board/system76/common/pnp.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/src/board/system76/common/pnp.c b/src/board/system76/common/pnp.c
index f6cc4b7..abdf663 100644
--- a/src/board/system76/common/pnp.c
+++ b/src/board/system76/common/pnp.c
@@ -13,22 +13,29 @@ volatile uint8_t __xdata __at(0x1204) IBMAE;
 volatile uint8_t __xdata __at(0x1205) IBCTL;
 
 uint8_t ec2i_read(uint8_t port) {
+    uint8_t ihd;
+
     while (IBCTL & (BIT(2) | BIT(1))) {}
-    IBCTL = 1;
-    IBMAE = 1;
     IHIOA = port;
-    IBCTL |= BIT(1);
+    IBMAE = BIT(0);
+    IBCTL = BIT(1);
+    IBCTL |= BIT(0);
     while (IBCTL & BIT(1)) {}
-    return IHD;
+    ihd = IHD;
+    IBMAE = 0;
+    IBCTL = 0;
+    return ihd;
 }
 
 void ec2i_write(uint8_t port, uint8_t data) {
     while (IBCTL & (BIT(2) | BIT(1))) {}
-    IBCTL = 1;
-    IBMAE = 1;
     IHIOA = port;
     IHD = data;
+    IBMAE = BIT(0);
+    IBCTL = BIT(0);
     while (IBCTL & BIT(2)) {}
+    IBMAE = 0;
+    IBCTL = 0;
 }
 
 uint8_t pnp_read(uint8_t reg) {