From a4c4c34ff9a7f02c134ab1b74f0a41594f7f3b26 Mon Sep 17 00:00:00 2001
From: Jeremy Soller <jeremy@system76.com>
Date: Tue, 1 Oct 2019 12:00:33 -0600
Subject: [PATCH] Use SMBus for console output

---
 src/board/system76/galp3-c/stdio.c | 60 +++++++++++++++++-------------
 src/ec/it8587e/include/ec/smbus.h  | 46 +++++++++++++++++++++++
 2 files changed, 81 insertions(+), 25 deletions(-)
 create mode 100644 src/ec/it8587e/include/ec/smbus.h

diff --git a/src/board/system76/galp3-c/stdio.c b/src/board/system76/galp3-c/stdio.c
index 3dbdeef..2cd8153 100644
--- a/src/board/system76/galp3-c/stdio.c
+++ b/src/board/system76/galp3-c/stdio.c
@@ -1,38 +1,48 @@
 #include <stdio.h>
 
-#include <arch/timer.h>
-#include <board/kbscan.h>
+#include <ec/smbus.h>
 
-// Wait 25 us
-// 65536 - (25 / 1.304) = 65517
-void parallel_delay(void) {
-    timer_mode_1(65517);
-    timer_wait();
-    timer_stop();
-}
+void i2c_write(unsigned char value) {
+    for (;;) {
+        // Wait for last command
+        while (HOSTAA & 1) {}
 
-// This takes a time of 25 us * 3 = 75 us
-// That produces a frequency of 13.333 KHz
-// Which produces a bitrate of 106.667 KHz
-void parallel_write(unsigned char value) {
-    // Make sure clock is high
-    KSOH1 = 0xFF;
-    parallel_delay();
+        // Clear result
+        HOSTAA = HOSTAA;
 
-    // Set value
-    KSOL = value;
-    parallel_delay();
+        // Clock down to 50 KHz
+        SCLKTSA = 1;
 
-    // Set clock low
-    KSOH1 = 0;
-    parallel_delay();
+        // Enable host interface with i2c compatibility
+        HOCTL2A = (1 << 1) | (1 << 0);
 
-    // Set clock high again
-    KSOH1 = 0xFF;
+        // Write value to 0x76
+        TRASLAA = (0x76 << 1) | (0 << 1);
+        HOCMDA = value;
+
+        // Start command
+        HOCTLA = (1 << 6) | (0b001 << 2);
+
+        // Wait for command to start
+        while (!(HOSTAA & 1)) {}
+
+        // Wait for command to finish
+        while (HOSTAA & 1) {}
+
+        // Read and clear status
+        uint8_t status = HOSTAA;
+        HOSTAA = status;
+
+        // If there were no errors, return
+        uint8_t error = (1 << 6) | (1 << 5) | (1 << 4) | (1 << 3) | (1 << 2);
+        if (!(status & error)) {
+            break;
+        }
+    }
 }
 
 int putchar(int c) {
     unsigned char byte = (unsigned char)c;
-    parallel_write(byte);
+    i2c_write(byte);
     return (int)byte;
 }
diff --git a/src/ec/it8587e/include/ec/smbus.h b/src/ec/it8587e/include/ec/smbus.h
new file mode 100644
index 0000000..2f864bb
--- /dev/null
+++ b/src/ec/it8587e/include/ec/smbus.h
@@ -0,0 +1,46 @@
+#ifndef _EC_SMBUS_H
+#define _EC_SMBUS_H
+
+#include <stdint.h>
+
+// Host status for channel A
+volatile uint8_t __xdata __at(0x1C00) HOSTAA;
+// Host control for channel A
+volatile uint8_t __xdata __at(0x1C01) HOCTLA;
+// Host command for channel A
+volatile uint8_t __xdata __at(0x1C02) HOCMDA;
+// Transmit slave address for channel A
+volatile uint8_t __xdata __at(0x1C03) TRASLAA;
+// Host data 0 for channel A
+volatile uint8_t __xdata __at(0x1C04) D0REGA;
+// Host data 1 for channel A
+volatile uint8_t __xdata __at(0x1C05) D1REGA;
+// Host block data byte for channel A
+volatile uint8_t __xdata __at(0x1C06) HOBDBA;
+// Packet error check for channel A
+volatile uint8_t __xdata __at(0x1C07) PECERCA;
+// Receive slave address for channel A
+volatile uint8_t __xdata __at(0x1C08) RESLADRA;
+// Receive slave address 2 for channel A
+volatile uint8_t __xdata __at(0x1C3F) RESLADR2A;
+// Slave data for channel A
+volatile uint8_t __xdata __at(0x1C09) SLDAA;
+// SMBus pin control for channel A
+volatile uint8_t __xdata __at(0x1C0A) SMBPCTLA;
+// Slave status for channel A
+volatile uint8_t __xdata __at(0x1C0B) SLSTAA;
+// Slave interrupt control for channel A
+volatile uint8_t __xdata __at(0x1C0C) SICRA;
+// Notify device address for channel A
+volatile uint8_t __xdata __at(0x1C0D) NDADRA;
+// Notify data low byte for channel A
+volatile uint8_t __xdata __at(0x1C0E) NDLBA;
+// Notify data high byte for channel A
+volatile uint8_t __xdata __at(0x1C0F) NDHBA;
+// Host control 2 for channel A
+volatile uint8_t __xdata __at(0x1C10) HOCTL2A;
+// SMCLK timing setting for channel A
+volatile uint8_t __xdata __at(0x1C10) SCLKTSA;
+
+
+#endif // _EC_SMBUS_H