hooks to use the fbscreen stuff provided by bls

Reference: /n/atom/patch/applied/fbscreen
Date: Sun Jan 10 20:03:12 CET 2016
Signed-off-by: quanstro@quanstro.net

--- /sys/src/9/bcm/screen.c	Sun Jan 10 20:03:01 2016
+++ /sys/src/9/bcm/screen.c	Sun Jan 10 20:03:03 2016
@@ -1,3 +1,7 @@
+/*
+ * bcm2385 framebuffer
+ */
+
 #include "u.h"
 #include "../port/lib.h"
 #include "mem.h"
@@ -9,10 +13,7 @@
 #include <memdraw.h>
 #include <cursor.h>
 #include "screen.h"
-
-/*
- * bcm2385 framebuffer
- */
+#include "fbscreen.h"
 
 enum {
 	Tabstop		= 4,
@@ -39,6 +40,7 @@
 Memimage *gscreen;
 
 static Memdata xgdata;
+static Fbscreen *fbscreen;
 
 static Memimage xgscreen =
 {
@@ -55,6 +57,10 @@
 	0,			/* flags */
 };
 
+static Fbscreen xfbscreen = {
+	&xgscreen,
+};
+
 static Memimage *conscol;
 static Memimage *back;
 static Memsubfont *memdefont;
@@ -116,6 +122,9 @@
 	if(mask->data->bdata == xgdata.bdata)
 		swcursoravoid(par->mr);
 
+	if(fbscreen != nil && fbscreen->draw != nil)
+		fbscreen->draw(fbscreen, par->r);
+
 	return 0;
 }
 
@@ -141,6 +150,7 @@
 void
 screeninit(void)
 {
+	char *s;
 	uchar *fb;
 	int set;
 	ulong chan;
@@ -180,6 +190,12 @@
 	screenwin();
 	screenputs = myscreenputs;
 	swcursorinit();
+
+	s = getconf("*scrhx8357d");
+	if(s != nil && atoi(s) > 0 && pitftinit(&xfbscreen) == 0){
+		fbscreen = &xfbscreen;
+		fbscreen->enable(fbscreen);
+	}
 }
 
 void
@@ -216,6 +232,8 @@
 blankscreen(int blank)
 {
 	fbblank(blank);
+	if(fbscreen != nil && fbscreen->blank != nil)
+		fbscreen->blank(fbscreen, blank);
 }
 
 static void
@@ -302,9 +320,13 @@
 	p = Pt(window.min.x, window.min.y+o);
 	memimagedraw(gscreen, r, gscreen, p, nil, p, S);
 	flushmemscreen(r);
+	if(fbscreen != nil && fbscreen->draw != nil)
+		fbscreen->draw(fbscreen, r);
 	r = Rpt(Pt(window.min.x, window.max.y-o), window.max);
 	memimagedraw(gscreen, r, back, ZP, nil, ZP, S);
 	flushmemscreen(r);
+	if(fbscreen != nil && fbscreen->draw != nil)
+		fbscreen->draw(fbscreen, r);
 
 	curpos.y -= o;
 }
--- /sys/src/9/bcm/fbscreen.h	Thu Jan  1 00:00:00 1970
+++ /sys/src/9/bcm/fbscreen.h	Sun Jan 10 20:03:03 2016
@@ -0,0 +1,20 @@
+typedef struct Fbscreen Fbscreen;
+typedef struct Hwscreen Hwscreen;
+
+struct Hwscreen {
+	char*	name;
+	Rectangle vis;
+
+	void	(*enable)(Fbscreen*);
+	void	(*disable)(Fbscreen*);
+	void	(*draw)(Fbscreen*, Rectangle);
+	void	(*flush)(Fbscreen*, Rectangle);
+	void	(*blank)(Fbscreen*, int);
+};
+
+struct Fbscreen {
+	Memimage *fb;
+	Hwscreen;
+};
+
+int pitftinit(Fbscreen*);