[PATCH v13 12/19] iommu/exynos: change rwlock to spinlock

[Shaik Ameer Basha]

From: Cho KyongHo <pullip.cho at samsung.com>

Since acquiring read_lock is not more frequent than write_lock, it is
not beneficial to use rwlock, this commit changes rwlock to spinlock.

Reviewed-by: Grant Grundler <grundler at chromium.org>
Signed-off-by: Cho KyongHo <pullip.cho at samsung.com>
Signed-off-by: Shaik Ameer Basha <shaik.ameer at samsung.com>
---
 drivers/iommu/exynos-iommu.c |   27 ++++++++++++++-------------
 1 file changed, 14 insertions(+), 13 deletions(-)

diff --git a/drivers/iommu/exynos-iommu.c b/drivers/iommu/exynos-iommu.c
index c1be65f..d89ad5f 100644
--- a/drivers/iommu/exynos-iommu.c
+++ b/drivers/iommu/exynos-iommu.c
@@ -164,7 +164,7 @@ struct sysmmu_drvdata {
 	struct clk *clk;
 	struct clk *clk_master;
 	int activations;
-	rwlock_t lock;
+	spinlock_t lock;
 	struct iommu_domain *domain;
 	phys_addr_t pgtable;
 };
@@ -263,12 +263,13 @@ static irqreturn_t exynos_sysmmu_irq(int irq, void *dev_id)
 	unsigned long addr = -1;
 	int ret = -ENOSYS;
 
-	read_lock(&data->lock);
-
 	WARN_ON(!is_sysmmu_active(data));
 
+	spin_lock(&data->lock);
+
 	if (!IS_ERR(data->clk_master))
 		clk_enable(data->clk_master);
+
 	itype = (enum exynos_sysmmu_inttype)
 		__ffs(__raw_readl(data->sfrbase + REG_INT_STATUS));
 	if (WARN_ON(!((itype >= 0) && (itype < SYSMMU_FAULT_UNKNOWN))))
@@ -302,7 +303,7 @@ static irqreturn_t exynos_sysmmu_irq(int irq, void *dev_id)
 	if (!IS_ERR(data->clk_master))
 		clk_disable(data->clk_master);
 
-	read_unlock(&data->lock);
+	spin_unlock(&data->lock);
 
 	return IRQ_HANDLED;
 }
@@ -312,7 +313,7 @@ static bool __exynos_sysmmu_disable(struct sysmmu_drvdata *data)
 	unsigned long flags;
 	bool disabled = false;
 
-	write_lock_irqsave(&data->lock, flags);
+	spin_lock_irqsave(&data->lock, flags);
 
 	if (!set_sysmmu_inactive(data))
 		goto finish;
@@ -330,7 +331,7 @@ static bool __exynos_sysmmu_disable(struct sysmmu_drvdata *data)
 	data->pgtable = 0;
 	data->domain = NULL;
 finish:
-	write_unlock_irqrestore(&data->lock, flags);
+	spin_unlock_irqrestore(&data->lock, flags);
 
 	if (disabled)
 		dev_dbg(data->sysmmu, "Disabled\n");
@@ -353,7 +354,7 @@ static int __exynos_sysmmu_enable(struct sysmmu_drvdata *data,
 	int ret = 0;
 	unsigned long flags;
 
-	write_lock_irqsave(&data->lock, flags);
+	spin_lock_irqsave(&data->lock, flags);
 
 	if (!set_sysmmu_active(data)) {
 		if (WARN_ON(pgtable != data->pgtable)) {
@@ -384,7 +385,7 @@ static int __exynos_sysmmu_enable(struct sysmmu_drvdata *data,
 
 	dev_dbg(data->sysmmu, "Enabled\n");
 finish:
-	write_unlock_irqrestore(&data->lock, flags);
+	spin_unlock_irqrestore(&data->lock, flags);
 
 	return ret;
 }
@@ -431,7 +432,7 @@ static void sysmmu_tlb_invalidate_entry(struct device *dev, unsigned long iova,
 	unsigned long flags;
 	struct sysmmu_drvdata *data = dev_get_drvdata(dev->archdata.iommu);
 
-	read_lock_irqsave(&data->lock, flags);
+	spin_lock_irqsave(&data->lock, flags);
 
 	if (is_sysmmu_active(data)) {
 		unsigned int maj;
@@ -465,7 +466,7 @@ static void sysmmu_tlb_invalidate_entry(struct device *dev, unsigned long iova,
 		dev_dbg(data->sysmmu, "Disabled. Skipping invalidating TLB.\n");
 	}
 
-	read_unlock_irqrestore(&data->lock, flags);
+	spin_unlock_irqrestore(&data->lock, flags);
 }
 
 void exynos_sysmmu_tlb_invalidate(struct device *dev)
@@ -473,7 +474,7 @@ void exynos_sysmmu_tlb_invalidate(struct device *dev)
 	unsigned long flags;
 	struct sysmmu_drvdata *data = dev_get_drvdata(dev->archdata.iommu);
 
-	read_lock_irqsave(&data->lock, flags);
+	spin_lock_irqsave(&data->lock, flags);
 
 	if (is_sysmmu_active(data)) {
 		if (!IS_ERR(data->clk_master))
@@ -488,7 +489,7 @@ void exynos_sysmmu_tlb_invalidate(struct device *dev)
 		dev_dbg(data->sysmmu, "Disabled. Skipping invalidating TLB.\n");
 	}
 
-	read_unlock_irqrestore(&data->lock, flags);
+	spin_unlock_irqrestore(&data->lock, flags);
 }
 
 static int exynos_sysmmu_probe(struct platform_device *pdev)
@@ -543,7 +544,7 @@ static int exynos_sysmmu_probe(struct platform_device *pdev)
 	}
 
 	data->sysmmu = dev;
-	rwlock_init(&data->lock);
+	spin_lock_init(&data->lock);
 	INIT_LIST_HEAD(&data->node);
 
 	platform_set_drvdata(pdev, data);
-- 
1.7.9.5