From 97502b61b071737a43322acd15b69b609aeb23b8 Mon Sep 17 00:00:00 2001
From: Jeremy Soller <jeremy@system76.com>
Date: Wed, 13 Nov 2019 19:26:04 -0700
Subject: [PATCH] Update avr i2c to match new common i2c library

---
 src/arch/avr/i2c.c                   | 87 +++++++++++++---------------
 src/board/arduino/mega2560/battery.c |  2 +-
 2 files changed, 40 insertions(+), 49 deletions(-)

diff --git a/src/arch/avr/i2c.c b/src/arch/avr/i2c.c
index e3255be..0ee788b 100644
--- a/src/arch/avr/i2c.c
+++ b/src/arch/avr/i2c.c
@@ -7,7 +7,7 @@
 
 #define TIMEOUT (F_CPU/1000)
 
-uint8_t i2c_start(uint8_t addr, bool read) {
+int i2c_start(uint8_t addr, bool read) {
 	uint32_t count;
 
 	// reset TWI control register
@@ -17,16 +17,10 @@ uint8_t i2c_start(uint8_t addr, bool read) {
 	// wait for end of transmission
 	count = TIMEOUT;
 	while(!(TWCR & (1<<TWINT)) && count > 0) count -= 1;
-	if (count == 0) {
-		printf("i2c_start timed out waiting to send start to 0x%X\n", addr);
-		return 1;
-	}
+	if (count == 0) return -1;
 
 	// check if the start condition was successfully transmitted
-	if((TWSR & 0xF8) != TW_START){
-		printf("i2c_start failed to send start condition to 0x%X\n", addr);
-		return 1;
-	}
+	if((TWSR & 0xF8) != TW_START) return -1;
 
 	// load slave addr into data register
 	TWDR = ((addr << 1) | read);
@@ -35,17 +29,11 @@ uint8_t i2c_start(uint8_t addr, bool read) {
 	// wait for end of transmission
 	count = TIMEOUT;
 	while(!(TWCR & (1<<TWINT)) && count > 0) count -= 1;
-	if (count == 0) {
-		printf("i2c_start timed out waiting to send addr to 0x%X\n", addr);
-		return 1;
-	}
+	if (count == 0) return -1;
 
 	// check if the device has acknowledged the READ / WRITE mode
 	uint8_t twst = TW_STATUS & 0xF8;
-	if ((twst != TW_MT_SLA_ACK) && (twst != TW_MR_SLA_ACK)) {
-		printf("i2c_start failed to receive ack from 0x%X\n", addr);
-		return 1;
-	}
+	if ((twst != TW_MT_SLA_ACK) && (twst != TW_MR_SLA_ACK)) return -1;
 
 	return 0;
 }
@@ -55,39 +43,42 @@ void i2c_stop(void) {
 	TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWSTO);
 }
 
-uint8_t i2c_write(uint8_t data) {
-	uint32_t count;
-
-	// load data into data register
-	TWDR = data;
-	// start transmission of data
-	TWCR = (1<<TWINT) | (1<<TWEN);
-	// wait for end of transmission
-	count = TIMEOUT;
-	while(!(TWCR & (1<<TWINT)) && count > 0) count -= 1;
-	if (count == 0) {
-		printf("i2c_write timed out waiting to send 0x%X\n", data);
-		return 1;
+int i2c_write(uint8_t * data, int length) {
+	int i;
+	for (i = 0; i < length; i++) {
+		// load data into data register
+		TWDR = data[i];
+		// start transmission of data
+		TWCR = (1<<TWINT) | (1<<TWEN);
+		// wait for end of transmission
+		uint32_t count = TIMEOUT;
+		while(!(TWCR & (1<<TWINT)) && count > 0) count -= 1;
+		// timed out
+		if (count == 0) return -1;
+		// failed to receive ack
+		if((TWSR & 0xF8) != TW_MT_DATA_ACK) return -1;
 	}
 
-	if( (TWSR & 0xF8) != TW_MT_DATA_ACK ){
-		printf("i2c_write failed to receive ack for 0x%X\n", data);
-		return 1;
+	return i;
+}
+
+int i2c_read(uint8_t * data, int length) {
+	int i;
+	for (i = 0; i < length; i++) {
+	    if ((i + 1) < length) {
+	    	// start TWI module and acknowledge data after reception
+	    	TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWEA);
+	    } else {
+	        // start receiving without acknowledging reception
+	    	TWCR = (1<<TWINT) | (1<<TWEN);
+	    }
+		// wait for end of transmission
+		uint32_t count = TIMEOUT;
+		while(!(TWCR & (1<<TWINT)) && count > 0) count -= 1;
+		if (count == 0) return -1;
+		// return received data from TWDR
+		data[i] = TWDR;
 	}
 
-	return 0;
-}
-
-uint8_t i2c_read(bool ack) {
-    if (ack) {
-    	// start TWI module and acknowledge data after reception
-    	TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWEA);
-    } else {
-        // start receiving without acknowledging reception
-    	TWCR = (1<<TWINT) | (1<<TWEN);
-    }
-	// wait for end of transmission
-	while( !(TWCR & (1<<TWINT)) );
-	// return received data from TWDR
-	return TWDR;
+	return i;
 }
diff --git a/src/board/arduino/mega2560/battery.c b/src/board/arduino/mega2560/battery.c
index 63f009f..6c9ede0 100644
--- a/src/board/arduino/mega2560/battery.c
+++ b/src/board/arduino/mega2560/battery.c
@@ -1,6 +1,6 @@
 #include <stdio.h>
 
-#include <board/i2c.h>
+#include <common/i2c.h>
 
 uint8_t smbus_read(uint8_t address, uint8_t command, uint16_t * data) {
     return i2c_get(address, command, (uint8_t *)data, 2);