From c757e8528a304214d0a9be2e99011b94bf374d37 Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Wed, 30 Jul 2014 11:33:25 +0100 Subject: [PATCH] iommu/arm-smmu: use page shift instead of page size to avoid division Arbitrary integer division is not available in all ARM CPUs, so the GCC may spit out calls to helper functions which are not implemented in the kernel. This patch avoids these problems in the SMMU driver by using page shift instead of page size, so that divisions by the page size (as required by the vSMMU code) can be expressed as a simple right shift. Signed-off-by: Will Deacon --- drivers/iommu/arm-smmu.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c index e8d311152203..482cc9e3138a 100644 --- a/drivers/iommu/arm-smmu.c +++ b/drivers/iommu/arm-smmu.c @@ -59,7 +59,7 @@ /* SMMU global address space */ #define ARM_SMMU_GR0(smmu) ((smmu)->base) -#define ARM_SMMU_GR1(smmu) ((smmu)->base + (smmu)->pagesize) +#define ARM_SMMU_GR1(smmu) ((smmu)->base + (1 << (smmu)->pgshift)) /* * SMMU global address space with conditional offset to access secure @@ -224,7 +224,7 @@ /* Translation context bank */ #define ARM_SMMU_CB_BASE(smmu) ((smmu)->base + ((smmu)->size >> 1)) -#define ARM_SMMU_CB(smmu, n) ((n) * (smmu)->pagesize) +#define ARM_SMMU_CB(smmu, n) ((n) * (1 << (smmu)->pgshift)) #define ARM_SMMU_CB_SCTLR 0x0 #define ARM_SMMU_CB_RESUME 0x8 @@ -354,7 +354,7 @@ struct arm_smmu_device { void __iomem *base; unsigned long size; - unsigned long pagesize; + unsigned long pgshift; #define ARM_SMMU_FEAT_COHERENT_WALK (1 << 0) #define ARM_SMMU_FEAT_STREAM_MATCH (1 << 1) @@ -1814,12 +1814,12 @@ static int arm_smmu_device_cfg_probe(struct arm_smmu_device *smmu) /* ID1 */ id = readl_relaxed(gr0_base + ARM_SMMU_GR0_ID1); - smmu->pagesize = (id & ID1_PAGESIZE) ? SZ_64K : SZ_4K; + smmu->pgshift = (id & ID1_PAGESIZE) ? 16 : 12; /* Check for size mismatch of SMMU address space from mapped region */ size = 1 << (((id >> ID1_NUMPAGENDXB_SHIFT) & ID1_NUMPAGENDXB_MASK) + 1); - size *= (smmu->pagesize << 1); + size *= 2 << smmu->pgshift; if (smmu->size != size) dev_warn(smmu->dev, "SMMU address space size (0x%lx) differs from mapped region size (0x%lx)!\n",