i2c:smbus_eeprom: Add a reset function to smbus_eeprom

Reset the contents to init data and reset the offset on a machine
reset.

Signed-off-by: Corey Minyard <cminyard@mvista.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>

hw/i2c/smbus_eeprom.c

@@ -108,7 +108,17 @@ static const VMStateDescription vmstate_smbus_eeprom = {
     }
 };
 
-static void smbus_eeprom_realize(DeviceState *dev, Error **errp)
+/*
+ * Reset the EEPROM contents to the initial state on a reset.  This
+ * isn't really how an EEPROM works, of course, but the general
+ * principle of QEMU is to restore function on reset to what it would
+ * be if QEMU was stopped and started.
+ *
+ * The proper thing to do would be to have a backing blockdev to hold
+ * the contents and restore that on startup, and not do this on reset.
+ * But until that time, act as if we had been stopped and restarted.
+ */
+static void smbus_eeprom_reset(DeviceState *dev)
 {
     SMBusEEPROMDevice *eeprom = SMBUS_EEPROM(dev);
 
@@ -116,6 +126,11 @@ static void smbus_eeprom_realize(DeviceState *dev, Error **errp)
     eeprom->offset = 0;
 }
 
+static void smbus_eeprom_realize(DeviceState *dev, Error **errp)
+{
+    smbus_eeprom_reset(dev);
+}
+
 static Property smbus_eeprom_properties[] = {
     DEFINE_PROP_PTR("data", SMBusEEPROMDevice, init_data),
     DEFINE_PROP_END_OF_LIST(),
@@ -127,6 +142,7 @@ static void smbus_eeprom_class_initfn(ObjectClass *klass, void *data)
     SMBusDeviceClass *sc = SMBUS_DEVICE_CLASS(klass);
 
     dc->realize = smbus_eeprom_realize;
+    dc->reset = smbus_eeprom_reset;
     sc->receive_byte = eeprom_receive_byte;
     sc->write_data = eeprom_write_data;
     dc->props = smbus_eeprom_properties;