This patch adds edid support to the qemu stdvga.  It is turned off by
default and can be enabled with the new edid property.  The patch also
adds xres and yres properties to specify the video mode you want the
guest use.  Works only with edid enabled and updated guest driver.

The mmio bar of the stdvga has some unused address space at the start.
It was reserved just in case it'll be needed for virtio, but it turned
out to not be needed for that.  So let's use that region to place the
EDID data block there.
Signed-off-by: NGerd Hoffmann <kraxel@redhat.com>
Message-id: 20180925075646.25114-6-kraxel@redhat.com

Add a qemu extented register range to the standard vga mmio bar.
Right nowe there are two registers:  One readonly register returning the
size of the region (so we can easily add more registers there if needed)
and one endian control register, so guests (especially ppc) can flip
the framebuffer endianness as they need it.
Signed-off-by: NGerd Hoffmann <kraxel@redhat.com>
Reviewed-by: NDavid Gibson <david@gibson.dropbear.id.au>

Add a standard vga variant which doesn't occupy any legacy
resources and thus can easily be used as secondary (or legacy-free)
graphics adapter.  Programming must be done using the MMIO bar.
Signed-off-by: NGerd Hoffmann <kraxel@redhat.com>

The bochs dispi interface traditionally uses port 0x1ce as 16bit index
register and port 0x1cf as 16bit data register.  The later is unaligned,
and probably for that reason the the data register was moved to 0x1d0
for non-x86 archs.

This patch makes the data register available at 0x1d0 on x86 too.  The
old x86 location is kept for compatibility reasons, so both 0x1cf and
0x1d0 can be used as data register on x86.
Signed-off-by: NGerd Hoffmann <kraxel@redhat.com>

Signed-off-by: NGerd Hoffmann <kraxel@redhat.com>
Signed-off-by: NBlue Swirl <blauwirbel@gmail.com>