[17/56] drm/i915: Page table helpers, and define renames

These page table helpers make the code much cleaner. There is some
room to use the arch/x86 header files. The reason I've opted not to is
in several cases, the definitions are dictated by the CONFIG_ options
which do not always indicate the restrictions in the GPU. While here,
clean up the defines to have more concise names, and consolidate between
gen6 and gen8 where appropriate.

v2: Use I915_PAGE_SIZE to remove PAGE_SIZE dep in the new code (Jesse)
Fix bugged I915_PTE_MASK define, which was unused (Chris)
BUG_ON bad length/size - taking directly from Chris (Chris)
define NUM_PTE (Chris)

I've made a lot of tiny errors in these helpers. Often I'd correct an
error only to introduce another one. While IGT was capable of catching
them, the tests often took a while to catch, and where hard/slow to
debug in the kernel. As a result, to test this, I compiled
i915_gem_gtt.h in userspace, and ran tests from userspace. What follows
isn't by any means complete, but it was able to catch lot of bugs. Gen8
is also untested, but since the current code is almost identical, I feel
pretty comfortable with that.

void test_pte(uint32_t base) {
        uint32_t ret;
        assert_pte_index((base + 0), 0);
        assert_pte_index((base + 1), 0);
        assert_pte_index((base + 0x1000), 1);
        assert_pte_index((base + (1<<22)), 0);
        assert_pte_index((base + ((1<<22) - 1)), 1023);
        assert_pte_index((base + (1<<21)), 512);

        assert_pte_count(base + 0, 0, 0);
        assert_pte_count(base + 0, 1, 1);
        assert_pte_count(base + 0, 0x1000, 1);
        assert_pte_count(base + 0, 0x1001, 2);
        assert_pte_count(base + 0, 1<<21, 512);

        assert_pte_count(base + 0, 1<<22, 1024);
        assert_pte_count(base + 0, (1<<22) - 1, 1024);
        assert_pte_count(base + (1<<21), 1<<22, 512);
        assert_pte_count(base + (1<<21), (1<<22)+1, 512);
        assert_pte_count(base + (1<<21), 10<<22, 512);
}

void test_pde(uint32_t base) {
        assert(gen6_pde_index(base + 0) == 0);
        assert(gen6_pde_index(base + 1) == 0);
        assert(gen6_pde_index(base + (1<<21)) == 0);
        assert(gen6_pde_index(base + (1<<22)) == 1);
        assert(gen6_pde_index(base + ((256<<22)))== 256);
        assert(gen6_pde_index(base + ((512<<22))) == 0);
        assert(gen6_pde_index(base + ((513<<22))) == 1); /* This is
actually not possible on gen6 */

        assert(gen6_pde_count(base + 0, 0) == 0);
        assert(gen6_pde_count(base + 0, 1) == 1);
        assert(gen6_pde_count(base + 0, 1<<21) == 1);
        assert(gen6_pde_count(base + 0, 1<<22) == 1);
        assert(gen6_pde_count(base + 0, (1<<22) + 0x1000) == 2);
        assert(gen6_pde_count(base + 0x1000, 1<<22) == 2);
        assert(gen6_pde_count(base + 0, 511<<22) == 511);
        assert(gen6_pde_count(base + 0, 512<<22) == 512);
        assert(gen6_pde_count(base + 0x1000, 512<<22) == 512);
        assert(gen6_pde_count(base + (1<<22), 512<<22) == 511);
}

int main()
{
        test_pde(0);
        while (1)
                test_pte(rand() & ~((1<<22) - 1));

        return 0;
}

Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
---
 drivers/gpu/drm/i915/i915_gem_gtt.c |  88 +++++++++++++-------------
 drivers/gpu/drm/i915/i915_gem_gtt.h | 123 +++++++++++++++++++++++++++++++++---
 2 files changed, 156 insertions(+), 55 deletions(-)

[17/56] drm/i915: Page table helpers, and define renames

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