drm/vc4: Add DPI driver

The DPI interface involves taking a ton of our GPIOs to be used as
outputs, and routing display signals over them in parallel.

v2: Use display_info.bus_formats[] to replace our custom DT
    properties.
v3: Rebase on V3D documentation changes.
v4: Fix rebase detritus from V3D documentation changes.

Signed-off-by: Eric Anholt <eric@anholt.net>
Acked-by: Rob Herring <robh@kernel.org>
diff --git a/drivers/gpu/drm/vc4/vc4_drv.h b/drivers/gpu/drm/vc4/vc4_drv.h
index fa2ad15..37cac59 100644
--- a/drivers/gpu/drm/vc4/vc4_drv.h
+++ b/drivers/gpu/drm/vc4/vc4_drv.h
@@ -16,6 +16,7 @@
 	struct vc4_hvs *hvs;
 	struct vc4_crtc *crtc[3];
 	struct vc4_v3d *v3d;
+	struct vc4_dpi *dpi;
 
 	struct drm_fbdev_cma *fbdev;
 
@@ -422,6 +423,10 @@
 /* vc4_drv.c */
 void __iomem *vc4_ioremap_regs(struct platform_device *dev, int index);
 
+/* vc4_dpi.c */
+extern struct platform_driver vc4_dpi_driver;
+int vc4_dpi_debugfs_regs(struct seq_file *m, void *unused);
+
 /* vc4_gem.c */
 void vc4_gem_init(struct drm_device *dev);
 void vc4_gem_destroy(struct drm_device *dev);