drm/radeon/kms: add pageflip ioctl support (v3)

This adds support for dri2 pageflipping.

v2: precision updates from Mario Kleiner.
v3: Multihead fixes from Mario Kleiner; missing crtc offset
    add note about update pending bit on pre-avivo chips

Signed-off-by: Alex Deucher <alexdeucher@gmail.com>
Signed-off-by: Mario Kleiner <mario.kleiner@tuebingen.mpg.de>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/radeon/r100.c b/drivers/gpu/drm/radeon/r100.c
index 8e10aa9..b2e2979 100644
--- a/drivers/gpu/drm/radeon/r100.c
+++ b/drivers/gpu/drm/radeon/r100.c
@@ -68,6 +68,54 @@
  * r100,rv100,rs100,rv200,rs200,r200,rv250,rs300,rv280
  */
 
+void r100_pre_page_flip(struct radeon_device *rdev, int crtc)
+{
+	struct radeon_crtc *radeon_crtc = rdev->mode_info.crtcs[crtc];
+	u32 tmp;
+
+	/* make sure flip is at vb rather than hb */
+	tmp = RREG32(RADEON_CRTC_OFFSET_CNTL + radeon_crtc->crtc_offset);
+	tmp &= ~RADEON_CRTC_OFFSET_FLIP_CNTL;
+	WREG32(RADEON_CRTC_OFFSET_CNTL + radeon_crtc->crtc_offset, tmp);
+
+	/* set pageflip to happen as late as possible in the vblank interval.
+	 * same field for crtc1/2
+	 */
+	tmp = RREG32(RADEON_CRTC_GEN_CNTL);
+	tmp &= ~RADEON_CRTC_VSTAT_MODE_MASK;
+	WREG32(RADEON_CRTC_GEN_CNTL, tmp);
+
+	/* enable the pflip int */
+	radeon_irq_kms_pflip_irq_get(rdev, crtc);
+}
+
+void r100_post_page_flip(struct radeon_device *rdev, int crtc)
+{
+	/* disable the pflip int */
+	radeon_irq_kms_pflip_irq_put(rdev, crtc);
+}
+
+u32 r100_page_flip(struct radeon_device *rdev, int crtc_id, u64 crtc_base)
+{
+	struct radeon_crtc *radeon_crtc = rdev->mode_info.crtcs[crtc_id];
+	u32 tmp = ((u32)crtc_base) | RADEON_CRTC_OFFSET__OFFSET_LOCK;
+
+	/* Lock the graphics update lock */
+	/* update the scanout addresses */
+	WREG32(RADEON_CRTC_OFFSET + radeon_crtc->crtc_offset, tmp);
+
+	/* Note: We don't wait for update_pending to assert, as this never
+	 * happens for some reason on R1xx - R4xx. Adds a bit of imprecision.
+	 */
+
+	/* Unlock the lock, so double-buffering can take place inside vblank */
+	tmp &= ~RADEON_CRTC_OFFSET__OFFSET_LOCK;
+	WREG32(RADEON_CRTC_OFFSET + radeon_crtc->crtc_offset, tmp);
+
+	/* Return current update_pending status: */
+	return RREG32(RADEON_CRTC_OFFSET + radeon_crtc->crtc_offset) & RADEON_CRTC_OFFSET__GUI_TRIG_OFFSET;
+}
+
 void r100_pm_get_dynpm_state(struct radeon_device *rdev)
 {
 	int i;
@@ -526,10 +574,12 @@
 	if (rdev->irq.gui_idle) {
 		tmp |= RADEON_GUI_IDLE_MASK;
 	}
-	if (rdev->irq.crtc_vblank_int[0]) {
+	if (rdev->irq.crtc_vblank_int[0] ||
+	    rdev->irq.pflip[0]) {
 		tmp |= RADEON_CRTC_VBLANK_MASK;
 	}
-	if (rdev->irq.crtc_vblank_int[1]) {
+	if (rdev->irq.crtc_vblank_int[1] ||
+	    rdev->irq.pflip[1]) {
 		tmp |= RADEON_CRTC2_VBLANK_MASK;
 	}
 	if (rdev->irq.hpd[0]) {
@@ -600,14 +650,22 @@
 		}
 		/* Vertical blank interrupts */
 		if (status & RADEON_CRTC_VBLANK_STAT) {
-			drm_handle_vblank(rdev->ddev, 0);
-			rdev->pm.vblank_sync = true;
-			wake_up(&rdev->irq.vblank_queue);
+			if (rdev->irq.pflip[0])
+				radeon_crtc_handle_flip(rdev, 0);
+			if (rdev->irq.crtc_vblank_int[0]) {
+				drm_handle_vblank(rdev->ddev, 0);
+				rdev->pm.vblank_sync = true;
+				wake_up(&rdev->irq.vblank_queue);
+			}
 		}
 		if (status & RADEON_CRTC2_VBLANK_STAT) {
-			drm_handle_vblank(rdev->ddev, 1);
-			rdev->pm.vblank_sync = true;
-			wake_up(&rdev->irq.vblank_queue);
+			if (rdev->irq.pflip[1])
+				radeon_crtc_handle_flip(rdev, 1);
+			if (rdev->irq.crtc_vblank_int[1]) {
+				drm_handle_vblank(rdev->ddev, 1);
+				rdev->pm.vblank_sync = true;
+				wake_up(&rdev->irq.vblank_queue);
+			}
 		}
 		if (status & RADEON_FP_DETECT_STAT) {
 			queue_hotplug = true;