[PATCH 09/39] drm/i915/gtt: Compute the radix for gen8 page table levels

[Chris Wilson]

The radix levels of each page directory are easily determined so replace
the numerous hardcoded constants with precomputed derived constants.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/i915_gem_gtt.c | 39 +++++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
index 2fc60e8acd9a..271305705c1c 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
@@ -868,6 +868,45 @@ static int gen8_ppgtt_notify_vgt(struct i915_ppgtt *ppgtt, bool create)
 	return 0;
 }
 
+/* Index shifts into the pagetable are offset by GEN8_PTE_SHIFT [12] */
+#define gen8_pd_shift(lvl) ((lvl) * ilog2(I915_PDES))
+#define gen8_pd_index(i, lvl) i915_pde_index((i), gen8_pd_shift(lvl))
+#define __gen8_pte_shift(lvl) (GEN8_PTE_SHIFT + gen8_pd_shift(lvl))
+#define __gen8_pte_index(a, lvl) i915_pde_index((a), __gen8_pte_shift(lvl))
+
+static inline unsigned int
+gen8_pd_range(u64 addr, u64 end, int lvl, unsigned int *idx)
+{
+	const int shift = gen8_pd_shift(lvl);
+	const u64 mask = ~0ull << gen8_pd_shift(lvl + 1);
+
+	GEM_BUG_ON(addr >= end);
+	end += ~mask >> gen8_pd_shift(1);
+
+	*idx = i915_pde_index(addr, shift);
+	if ((addr ^ end) & mask)
+		return I915_PDES - *idx;
+	else
+		return i915_pde_index(end, shift) - *idx;
+}
+
+static inline bool gen8_pd_subsumes(u64 addr, u64 end, int lvl)
+{
+	const u64 mask = ~0ull << gen8_pd_shift(lvl + 1);
+
+	GEM_BUG_ON(addr >= end);
+	return (addr ^ end) & mask && (addr & ~mask) == 0;
+}
+
+static inline unsigned int gen8_pt_count(u64 addr, u64 end)
+{
+	GEM_BUG_ON(addr >= end);
+	if ((addr ^ end) & ~I915_PDE_MASK)
+		return I915_PDES - (addr & I915_PDE_MASK);
+	else
+		return end - addr;
+}
+
 static void gen8_free_page_tables(struct i915_address_space *vm,
 				  struct i915_page_directory *pd)
 {
-- 
2.20.1