rpi: a backend for Raspberry Pi

Add a new backend for the Raspberry Pi.

This backend uses the DispmanX API to initialise the display, and create
an EGLSurface, so that GLESv2 rendering is shown on the "framebuffer".
No X server is involved. All compositing happens through GLESv2.

The created EGLSurface is specifically configured as buffer content
preserving, otherwise Weston wouuld show only the latest damage and
everything else was black. This may be sub-optimal, since we are not
alternating between two buffers, like the DRM backend is, and content
preserving may imply a fullscreen copy on each frame.

Page flips are not properly hooked up yet. The display update will
block, and we use a timer to call weston_output_finish_frame(), just
like the x11 backend does.

This backend handles the VT and tty just like the DRM backend does.
While VT switching works in theory, the display output seems to be
frozen while switched away from Weston. You can still switch back.

Seats and connectors cannot be explicitly specified, and multiple seats
are not expected.

Udev is used to find the input devices. Input devices are opened
directly, weston-launch is not supported at this time. You may need to
confirm that your pi user has access to input device nodes.

The Raspberry Pi backend is built by default. It can be build-tested
without the Raspberry Pi headers and libraries, because we provide stubs
in rpi-bcm-stubs.h, but such resulting binary is non-functional. If
using stubs, the backend is built but not installed.

VT and tty handling, and udev related code are pretty much copied from
the DRM backend, hence the copyrights. The rpi-bcm-stubs.h code is
copied from the headers on Raspberry Pi, including their copyright
notice, and modified.

Signed-off-by: Pekka Paalanen <ppaalanen@gmail.com>

configure.ac

@@ -128,6 +128,24 @@ if test x$enable_android_compositor = xyes; then
   PKG_CHECK_MODULES(ANDROID_COMPOSITOR, [mtdev >= 1.1.0])
 fi
 
+
+AC_ARG_ENABLE(rpi-compositor,
+	      AS_HELP_STRING([--disable-rpi-compositor],
+	                     [do not build the Raspberry Pi backend]),,
+	      enable_rpi_compositor=yes)
+AM_CONDITIONAL(ENABLE_RPI_COMPOSITOR, test "x$enable_rpi_compositor" = "xyes")
+have_bcm_host="no"
+if test x$enable_rpi_compositor = xyes; then
+  AC_DEFINE([BUILD_RPI_COMPOSITOR], [1], [Build the compositor for Raspberry Pi])
+  PKG_CHECK_MODULES(RPI_COMPOSITOR, [libudev >= 136 mtdev >= 1.1.0])
+  PKG_CHECK_MODULES(RPI_BCM_HOST, [bcm_host],
+                    [have_bcm_host="yes"
+                     AC_DEFINE([HAVE_BCM_HOST], [1], [have Raspberry Pi BCM headers])],
+                    [AC_MSG_WARN([Raspberry Pi BCM host libraries not found, will use stubs instead.])])
+fi
+AM_CONDITIONAL(INSTALL_RPI_COMPOSITOR, test "x$have_bcm_host" = "xyes")
+
+
 AC_ARG_WITH(cairo-glesv2,
             AS_HELP_STRING([--with-cairo-glesv2],
                            [Use GLESv2 cairo instead of full GL]))

src/Makefile.am

@@ -82,6 +82,12 @@ module_LTLIBRARIES =				\
 # The real backend is built by the Android build system.
 noinst_LTLIBRARIES = $(android_backend)
 
+if INSTALL_RPI_COMPOSITOR
+module_LTLIBRARIES += $(rpi_backend)
+else
+noinst_LTLIBRARIES += $(rpi_backend)
+endif
+
 if ENABLE_X11_COMPOSITOR
 x11_backend = x11-backend.la
 x11_backend_la_LDFLAGS = -module -avoid-version
@@ -145,6 +151,27 @@ android_backend_la_SOURCES =			\
 	android-framebuffer.h
 endif
 
+if ENABLE_RPI_COMPOSITOR
+rpi_backend = rpi-backend.la
+rpi_backend_la_LDFLAGS = -module -avoid-version
+rpi_backend_la_LIBADD = $(COMPOSITOR_LIBS)	\
+	$(RPI_COMPOSITOR_LIBS)			\
+	$(RPI_BCM_HOST_LIBS)			\
+	../shared/libshared.la
+rpi_backend_la_CFLAGS =				\
+	$(GCC_CFLAGS)				\
+	$(COMPOSITOR_CFLAGS)			\
+	$(RPI_COMPOSITOR_CFLAGS)		\
+	$(RPI_BCM_HOST_CFLAGS)
+rpi_backend_la_SOURCES =			\
+	compositor-rpi.c			\
+	rpi-bcm-stubs.h 			\
+	tty.c					\
+	evdev.c					\
+	evdev.h					\
+	evdev-touchpad.c
+endif
+
 if ENABLE_HEADLESS_COMPOSITOR
 headless_backend = headless-backend.la
 headless_backend_la_LDFLAGS = -module -avoid-version

src/rpi-bcm-stubs.h

+/*
+Copyright (c) 2012, Broadcom Europe Ltd
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+    * Redistributions of source code must retain the above copyright
+      notice, this list of conditions and the following disclaimer.
+    * Redistributions in binary form must reproduce the above copyright
+      notice, this list of conditions and the following disclaimer in the
+      documentation and/or other materials provided with the distribution.
+    * Neither the name of the copyright holder nor the
+      names of its contributors may be used to endorse or promote products
+      derived from this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY
+DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
+
+/*
+ * This file provides just enough types and stubs, so that the rpi-backend
+ * can be built without the real headers and libraries of the Raspberry Pi.
+ *
+ * This file CANNOT be used to build a working rpi-backend, it is intended
+ * only for build-testing, when the proper headers are not available.
+ */
+
+#ifndef RPI_BCM_STUBS
+#define RPI_BCM_STUBS
+
+#include <stdint.h>
+
+/* from /opt/vc/include/bcm_host.h */
+
+static inline void bcm_host_init(void) {}
+static inline void bcm_host_deinit(void) {}
+
+/* from /opt/vc/include/interface/vctypes/vc_display_types.h */
+
+typedef enum
+{
+	VCOS_DISPLAY_INPUT_FORMAT_INVALID = 0,
+} DISPLAY_INPUT_FORMAT_T;
+
+/* from /opt/vc/include/interface/vctypes/vc_image_types.h */
+
+typedef struct tag_VC_RECT_T {
+	int32_t x;
+	int32_t y;
+	int32_t width;
+	int32_t height;
+} VC_RECT_T;
+
+typedef enum {
+	VC_IMAGE_ROT0,
+} VC_IMAGE_TRANSFORM_T;
+
+/* from /opt/vc/include/interface/vmcs_host/vc_dispmanx_types.h */
+
+typedef uint32_t DISPMANX_DISPLAY_HANDLE_T;
+typedef uint32_t DISPMANX_UPDATE_HANDLE_T;
+typedef uint32_t DISPMANX_ELEMENT_HANDLE_T;
+typedef uint32_t DISPMANX_RESOURCE_HANDLE_T;
+typedef uint32_t DISPMANX_PROTECTION_T;
+
+#define DISPMANX_NO_HANDLE 0
+#define DISPMANX_PROTECTION_NONE  0
+#define DISPMANX_ID_HDMI      2
+
+typedef enum {
+	/* Bottom 2 bits sets the alpha mode */
+	DISPMANX_FLAGS_ALPHA_FROM_SOURCE = 0,
+	DISPMANX_FLAGS_ALPHA_FIXED_ALL_PIXELS = 1,
+	DISPMANX_FLAGS_ALPHA_FIXED_NON_ZERO = 2,
+	DISPMANX_FLAGS_ALPHA_FIXED_EXCEED_0X07 = 3,
+
+	DISPMANX_FLAGS_ALPHA_PREMULT = 1 << 16,
+	DISPMANX_FLAGS_ALPHA_MIX = 1 << 17
+} DISPMANX_FLAGS_ALPHA_T;
+
+typedef struct {
+	DISPMANX_FLAGS_ALPHA_T flags;
+	uint32_t opacity;
+	DISPMANX_RESOURCE_HANDLE_T mask;
+} VC_DISPMANX_ALPHA_T;
+
+typedef struct {
+	int32_t width;
+	int32_t height;
+	VC_IMAGE_TRANSFORM_T transform;
+	DISPLAY_INPUT_FORMAT_T input_format;
+} DISPMANX_MODEINFO_T;
+
+typedef enum {
+	DISPMANX_NO_ROTATE = 0,
+} DISPMANX_TRANSFORM_T;
+
+typedef struct {
+	uint32_t dummy;
+} DISPMANX_CLAMP_T;
+
+/* from /opt/vc/include/interface/vmcs_host/vc_dispmanx.h */
+
+static inline int
+vc_dispmanx_rect_set(VC_RECT_T *rect, uint32_t x_offset, uint32_t y_offset,
+		     uint32_t width, uint32_t height)
+{
+	rect->x = x_offset;
+	rect->y = y_offset;
+	rect->width = width;
+	rect->height = height;
+	return 0;
+}
+
+static inline DISPMANX_DISPLAY_HANDLE_T
+vc_dispmanx_display_open(uint32_t device)
+{
+	return -1;
+}
+
+static inline int
+vc_dispmanx_display_close(DISPMANX_DISPLAY_HANDLE_T display)
+{
+	return -1;
+}
+
+static inline int
+vc_dispmanx_display_get_info(DISPMANX_DISPLAY_HANDLE_T display,
+			     DISPMANX_MODEINFO_T *pinfo)
+{
+	return -1;
+}
+
+static inline DISPMANX_UPDATE_HANDLE_T
+vc_dispmanx_update_start(int32_t priority)
+{
+	return -1;
+}
+
+static inline DISPMANX_ELEMENT_HANDLE_T
+vc_dispmanx_element_add(DISPMANX_UPDATE_HANDLE_T update,
+			DISPMANX_DISPLAY_HANDLE_T display,
+			int32_t layer,
+			const VC_RECT_T *dest_rect,
+			DISPMANX_RESOURCE_HANDLE_T src,
+			const VC_RECT_T *src_rect,
+			DISPMANX_PROTECTION_T protection,
+			VC_DISPMANX_ALPHA_T *alpha,
+			DISPMANX_CLAMP_T *clamp,
+			DISPMANX_TRANSFORM_T transform)
+{
+	return -1;
+}
+
+static inline int
+vc_dispmanx_element_remove(DISPMANX_UPDATE_HANDLE_T update,
+			   DISPMANX_ELEMENT_HANDLE_T element)
+{
+	return -1;
+}
+
+static inline int
+vc_dispmanx_update_submit_sync(DISPMANX_UPDATE_HANDLE_T update)
+{
+	return -1;
+}
+
+/* from /opt/vc/include/EGL/eglplatform.h */
+
+typedef struct {
+	DISPMANX_ELEMENT_HANDLE_T element;
+	int width;
+	int height;
+} EGL_DISPMANX_WINDOW_T;
+
+#endif /* RPI_BCM_STUBS */