Add i2c capability for AVR

src/board/arduino/mega2560/battery.c

@@ -0,0 +1,43 @@
+#include <stdio.h>
+
+#include <board/i2c.h>
+
+uint8_t smbus_read(uint8_t address, uint8_t command, uint16_t * data) {
+    return i2c_get(address, command, (uint8_t *)data, 2);
+}
+
+void battery_debug(void) {
+    uint16_t data = 0;
+    uint8_t err = 0;
+
+    #define command(N, A, V) { \
+        printf(#N ": "); \
+        err = smbus_read(A, V, &data); \
+        if (err) { \
+            printf("ERROR %02X\n", err); \
+            return; \
+        } \
+        printf("%04X\n", data); \
+    }
+
+    printf("Battery:\n");
+    command(Temperature, 0x0B, 0x08);
+    command(Voltage, 0x0B, 0x09);
+    command(Current, 0x0B, 0x0A);
+    command(Charge, 0x0B, 0x0D);
+
+    printf("Charger:\n");
+    command(ChargeOption0, 0x09, 0x12);
+    command(ChargeOption1, 0x09, 0x3B);
+    command(ChargeOption2, 0x09, 0x38);
+    command(ChargeOption3, 0x09, 0x37);
+    command(ChargeCurrent, 0x09, 0x14);
+    command(ChargeVoltage, 0x09, 0x15);
+    command(DishargeCurrent, 0x09, 0x39);
+    command(InputCurrent, 0x09, 0x3F);
+    command(ProchotOption0, 0x09, 0x3C);
+    command(ProchotOption1, 0x09, 0x3D);
+    command(ProchotStatus, 0x09, 0x3A);
+
+    #undef command
+}

src/board/arduino/mega2560/i2c.c

@@ -0,0 +1,10 @@
+#include <avr/io.h>
+
+#include <board/cpu.h>
+#include <board/i2c.h>
+
+void i2c_init(unsigned long baud) {
+	TWAR = 0;
+	TWBR = (uint8_t)(((F_CPU / baud) - 16 ) / 2);
+	TWCR = 0;
+}

src/board/arduino/mega2560/include/board/battery.h

@@ -0,0 +1,6 @@
+#ifndef _BOARD_BATTERY_H
+#define _BOARD_BATTERY_H
+
+void battery_debug(void);
+
+#endif // _BOARD_BATTERY_H

src/board/arduino/mega2560/include/board/i2c.h

@@ -0,0 +1,6 @@
+#ifndef _BOARD_I2C_H
+#define _BOARD_I2C_H
+
+void i2c_init(unsigned long baud);
+
+#endif // _BOARD_I2C_H

src/board/arduino/mega2560/main.c

@@ -2,9 +2,12 @@
 
 #include <arch/gpio.h>
 #include <arch/uart.h>
+#include <board/battery.h>
+#include <board/i2c.h>
 
 void init(void) {
     uart_stdio_init(0, __CONSOLE_BAUD__);
+    i2c_init(50000);
 }
 
 struct Gpio LED = GPIO(B, 7);
@@ -15,10 +18,14 @@ int main(void) {
     gpio_set_dir(&LED, true);
     gpio_set(&LED, false);
     printf("Hello from System76 EC for the Arduino Mega 2560!\n");
+
+    battery_debug();
+
     for (;;) {
         int c = getchar();
         if (c == '\r') {
             putchar('\n');
+            battery_debug();
         } else if (c > 0) {
             putchar(c);
         }