i2c: initial bus drivers for am335x and dm37xx

Change-Id: I478704fbf30dbf6d3382bcbfb11e75b512c032a1

etc/system.conf

@@ -589,6 +589,25 @@ service gpio
 
 };
 
+service i2c
+{
+	system
+		PRIVCTL		#  4
+		IRQCTL          # 19
+	;
+	irq
+		# DM37XX (BeagleBoard-xM)
+		56	# I2C module 1
+		57	# I2C module 2
+		61	# I2C module 3
+		# AM335X (BeagleBone)
+		70	# I2C module 1
+		71	# I2C module 2
+		30	# I2C module 3
+	;
+	ipc SYSTEM RS DS;
+};
+
 service vbox
 {
 	system

etc/usr/rc

@@ -183,6 +183,19 @@ start)
     daemonize syslogd
     echo .
 
+    # i2c only supported on ARM at the moment
+    if [ $ARCH = earm ]
+    then
+	echo -n "Starting i2c subsystem: "
+	for bus in 1 2 3
+	do
+		test -e /dev/i2c-${bus} || (cd /dev && MAKEDEV i2c-${bus})
+		up i2c -dev /dev/i2c-${bus} -label i2c.${bus} \
+			-args instance=${bus}
+	done
+	echo .
+    fi
+
     if [ "$net" ]
     then
 	if [ -f /etc/rc.net ]