drm/vc4: Add KMS support for Raspberry Pi.

This is enough for fbcon and bringing up X using
xf86-video-modesetting.  It doesn't support the 3D accelerator or
power management yet.

v2: Drop FB_HELPER select thanks to Archit's patches.  Do manual init
    ordering instead of using the .load hook.  Structure registration
    more like tegra's, but still using the typical "component" code.
    Drop no-op hooks for atomic_begin and mode_fixup() now that
    they're optional.  Drop sentinel in Makefile.  Fix minor style
    nits I noticed on another reread.

v3: Use the new bcm2835 clk driver to manage pixel/HSM clocks instead
    of having a fixed video mode.  Use exynos-style component driver
    matching instead of devicetree nodes to list the component driver
    instances.  Rename compatibility strings to say bcm2835, and
    distinguish pv0/1/2.  Clean up some h/vsync code, and add in
    interlaced mode setup.  Fix up probe/bind error paths.  Use
    bitops.h macros for vc4_regs.h

v4: Include i2c.h, allow building under COMPILE_TEST, drop msleep now
    that other bugs have been fixed, add timeouts to cpu_relax()
    loops, rename hpd-gpio to hpd-gpios.

Signed-off-by: Eric Anholt <eric@anholt.net>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/vc4/vc4_kms.c b/drivers/gpu/drm/vc4/vc4_kms.c
new file mode 100644
index 0000000..c241c8f
--- /dev/null
+++ b/drivers/gpu/drm/vc4/vc4_kms.c
@@ -0,0 +1,54 @@
+/*
+ * Copyright (C) 2015 Broadcom
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+/**
+ * DOC: VC4 KMS
+ *
+ * This is the general code for implementing KMS mode setting that
+ * doesn't clearly associate with any of the other objects (plane,
+ * crtc, HDMI encoder).
+ */
+
+#include "drm_crtc.h"
+#include "drm_atomic_helper.h"
+#include "drm_crtc_helper.h"
+#include "drm_plane_helper.h"
+#include "drm_fb_cma_helper.h"
+#include "vc4_drv.h"
+
+static const struct drm_mode_config_funcs vc4_mode_funcs = {
+	.atomic_check = drm_atomic_helper_check,
+	.atomic_commit = drm_atomic_helper_commit,
+	.fb_create = drm_fb_cma_create,
+};
+
+int vc4_kms_load(struct drm_device *dev)
+{
+	int ret;
+
+	ret = drm_vblank_init(dev, dev->mode_config.num_crtc);
+	if (ret < 0) {
+		dev_err(dev->dev, "failed to initialize vblank\n");
+		return ret;
+	}
+
+	dev->mode_config.max_width = 2048;
+	dev->mode_config.max_height = 2048;
+	dev->mode_config.funcs = &vc4_mode_funcs;
+	dev->mode_config.preferred_depth = 24;
+
+	drm_mode_config_reset(dev);
+
+	drm_fbdev_cma_init(dev, 32,
+			   dev->mode_config.num_crtc,
+			   dev->mode_config.num_connector);
+
+	drm_kms_helper_poll_init(dev);
+
+	return 0;
+}