iommu/tegra-smmu: Extract tegra_smmu_pte_get_use()

Extract the use count reference accounting into a separate function and
separate it from allocating the PTE.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
[treding@nvidia.com: extract and write commit message]
Signed-off-by: Thierry Reding <treding@nvidia.com>

1 files changed, 11 insertions, 6 deletions

diff --git a/drivers/iommu/tegra-smmu.c b/drivers/iommu/tegra-smmu.c
index 27d31f62a822..74ad1f43265a 100644
--- a/drivers/iommu/tegra-smmu.c
+++ b/drivers/iommu/tegra-smmu.c
@@ -522,7 +522,7 @@ static u32 *tegra_smmu_pte_lookup(struct tegra_smmu_as *as, unsigned long iova,
 static u32 *as_get_pte(struct tegra_smmu_as *as, dma_addr_t iova,
                        dma_addr_t *dmap)
 {
-        u32 *pd = page_address(as->pd), *pt;
+        u32 *pd = page_address(as->pd);
         unsigned int pde = iova_pd_index(iova);
         struct tegra_smmu *smmu = as->smmu;
 
@@ -563,13 +563,14 @@ static u32 *as_get_pte(struct tegra_smmu_as *as, dma_addr_t iova,
                 *dmap = smmu_pde_to_dma(pd[pde]);
         }
 
-        pt = tegra_smmu_pte_offset(as->pts[pde], iova);
+        return tegra_smmu_pte_offset(as->pts[pde], iova);
+}
 
-        /* Keep track of entries in this page table. */
-        if (*pt == 0)
-                as->count[pde]++;
+static void tegra_smmu_pte_get_use(struct tegra_smmu_as *as, unsigned long iova)
+{
+        unsigned int pd_index = iova_pd_index(iova);
 
-        return pt;
+        as->count[pd_index]++;
 }
 
 static void tegra_smmu_pte_put_use(struct tegra_smmu_as *as, unsigned long iova)
@@ -630,6 +631,10 @@ static int tegra_smmu_map(struct iommu_domain *domain, unsigned long iova,
         if (!pte)
                 return -ENOMEM;
 
+        /* If we aren't overwriting a pre-existing entry, increment use */
+        if (*pte == 0)
+                tegra_smmu_pte_get_use(as, iova);
+
         tegra_smmu_set_pte(as, iova, pte, pte_dma,
                            __phys_to_pfn(paddr) | SMMU_PTE_ATTR);