drm/i915: Extract PPGTT pte encoding

HSW will change the PTE encoding, and laying this out now will be
helpful when we're ready to implement that. More importantly, GGTT and
PPGTT PTE encoding is quite similar, so moving this out into a helper
function will enable us to lance the AGP layer.

Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_gem_gtt.c

@@ -30,6 +30,17 @@
 
 typedef uint32_t gtt_pte_t;
 
+static inline gtt_pte_t pte_encode(struct drm_device *dev,
+				   dma_addr_t addr,
+				   gtt_pte_t cache_bits)
+{
+	gtt_pte_t pte = GEN6_PTE_VALID;
+	pte |= GEN6_PTE_ADDR_ENCODE(addr);
+	pte |= cache_bits;
+
+	return pte;
+}
+
 /* PPGTT support for Sandybdrige/Gen6 and later */
 static void i915_ppgtt_clear_range(struct i915_hw_ppgtt *ppgtt,
 				   unsigned first_entry,
@@ -41,8 +52,8 @@ static void i915_ppgtt_clear_range(struct i915_hw_ppgtt *ppgtt,
 	unsigned first_pte = first_entry % I915_PPGTT_PT_ENTRIES;
 	unsigned last_pte, i;
 
-	scratch_pte = GEN6_PTE_ADDR_ENCODE(ppgtt->scratch_page_dma_addr);
-	scratch_pte |= GEN6_PTE_VALID | GEN6_PTE_CACHE_LLC;
+	scratch_pte = pte_encode(ppgtt->dev, ppgtt->scratch_page_dma_addr,
+				 GEN6_PTE_CACHE_LLC);
 
 	while (num_entries) {
 		last_pte = first_pte + num_entries;
@@ -173,7 +184,7 @@ static void i915_ppgtt_insert_sg_entries(struct i915_hw_ppgtt *ppgtt,
 					 unsigned first_entry,
 					 gtt_pte_t pte_flags)
 {
-	gtt_pte_t *pt_vaddr, pte;
+	gtt_pte_t *pt_vaddr;
 	unsigned act_pd = first_entry / I915_PPGTT_PT_ENTRIES;
 	unsigned first_pte = first_entry % I915_PPGTT_PT_ENTRIES;
 	unsigned i, j, m, segment_len;
@@ -191,8 +202,8 @@ static void i915_ppgtt_insert_sg_entries(struct i915_hw_ppgtt *ppgtt,
 
 		for (j = first_pte; j < I915_PPGTT_PT_ENTRIES; j++) {
 			page_addr = sg_dma_address(sg) + (m << PAGE_SHIFT);
-			pte = GEN6_PTE_ADDR_ENCODE(page_addr);
-			pt_vaddr[j] = pte | pte_flags;
+			pt_vaddr[j] = pte_encode(ppgtt->dev, page_addr,
+						 pte_flags);
 
 			/* grab the next page */
 			if (++m == segment_len) {