drm/i915: extract dri1 breadcrumb update from irq handler

... and hide it in i915_dma.c.

This way all the legacy stuff dealing with READ_BREADCRUMB and
LP_RING and friends is in i915_dma.c.

v2: Rebase on top of Chris Wilson's rework irq handling code.

Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Acked-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
index 6f6c4bd..30cb446 100644
--- a/drivers/gpu/drm/i915/i915_dma.c
+++ b/drivers/gpu/drm/i915/i915_dma.c
@@ -47,6 +47,19 @@
 #include <acpi/video.h>
 #include <asm/pat.h>
 
+void i915_update_dri1_breadcrumb(struct drm_device *dev)
+{
+	drm_i915_private_t *dev_priv = dev->dev_private;
+	struct drm_i915_master_private *master_priv;
+
+	if (dev->primary->master) {
+		master_priv = dev->primary->master->driver_priv;
+		if (master_priv->sarea_priv)
+			master_priv->sarea_priv->last_dispatch =
+				READ_BREADCRUMB(dev_priv);
+	}
+}
+
 static void i915_write_hws_pga(struct drm_device *dev)
 {
 	drm_i915_private_t *dev_priv = dev->dev_private;