Add an interface that allows drivers to claim a framebuffer and check

whether another driver has already claimed a framebuffer.  Use this in
radeondrm(4) and simplefb(4) to prevent the latter from attaching if
radeondrm(4) is attached to the hardware that provides the framebuffer
set up by the firmware.

ok mlarkin@

1 files changed, 5 insertions, 1 deletions

diff --git a/sys/dev/fdt/simplefb.c b/sys/dev/fdt/simplefb.c
index 3be2ac6d004..6f031953a3c 100644
--- a/sys/dev/fdt/simplefb.c
+++ b/sys/dev/fdt/simplefb.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: simplefb.c,v 1.4 2018/07/31 17:25:55 fcambus Exp $	*/
+/*	$OpenBSD: simplefb.c,v 1.5 2018/08/27 09:30:07 kettenis Exp $	*/
 /*
  * Copyright (c) 2016 Mark Kettenis
  *
@@ -110,6 +110,10 @@ simplefb_match(struct device *parent, void *match, void *aux)
 {
 	struct fdt_attach_args *faa = aux;
 
+	/* Don't attach if another driver already claimed our framebuffer. */
+	if (faa->fa_nreg > 0 && rasops_check_framebuffer(faa->fa_reg[0].addr))
+		return 0;
+
 	return OF_is_compatible(faa->fa_node, "simple-framebuffer");
 }