hw/m68k: add a dummy SWIM floppy controller

SWIM (Sander-Wozniak Integrated Machine) is the floppy controller of
the 680x0 Macintosh.

This patch introduces only the basic support: it allows to switch from
IWM (Integrated WOZ Machine) mode to the SWIM mode and makes the linux
driver happy.

It cannot read any floppy image.

Co-developed-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
Reviewed-by: Hervé Poussineau <hpoussin@reactos.org>
Message-Id: <20191026164546.30020-10-laurent@vivier.eu>

MAINTAINERS

@@ -923,9 +923,11 @@ S: Maintained
 F: hw/misc/mac_via.c
 F: hw/nubus/*
 F: hw/display/macfb.c
+F: hw/block/swim.c
 F: include/hw/misc/mac_via.h
 F: include/hw/nubus/*
 F: include/hw/display/macfb.h
+F: include/hw/block/swim.h
 
 MicroBlaze Machines
 -------------------

hw/block/Kconfig

@@ -37,3 +37,6 @@ config VHOST_USER_BLK
     # Only PCI devices are provided for now
     default y if VIRTIO_PCI
     depends on VIRTIO && VHOST_USER && LINUX
+
+config SWIM
+    bool

hw/block/Makefile.objs

@@ -8,6 +8,7 @@ common-obj-$(CONFIG_XEN) += xen-block.o
 common-obj-$(CONFIG_ECC) += ecc.o
 common-obj-$(CONFIG_ONENAND) += onenand.o
 common-obj-$(CONFIG_NVME_PCI) += nvme.o
+common-obj-$(CONFIG_SWIM) += swim.o
 
 obj-$(CONFIG_SH4) += tc58128.o