[PATCH v4 16/26] iommu/arm-smmu-v3: Add dev_to_master() helper

[Jean-Philippe Brucker <jean-philippe@linaro.org>]

We'll need to frequently find the SMMU master associated to a device
when implementing SVA. Move it to a separate function.

Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
---
 drivers/iommu/arm-smmu-v3.c | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
index 77a846440ba6..54bd6913d648 100644
--- a/drivers/iommu/arm-smmu-v3.c
+++ b/drivers/iommu/arm-smmu-v3.c
@@ -747,6 +747,15 @@ static struct arm_smmu_domain *to_smmu_domain(struct iommu_domain *dom)
 	return container_of(dom, struct arm_smmu_domain, domain);
 }
 
+static struct arm_smmu_master *dev_to_master(struct device *dev)
+{
+	struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
+
+	if (!fwspec)
+		return NULL;
+	return fwspec->iommu_priv;
+}
+
 static void parse_driver_options(struct arm_smmu_device *smmu)
 {
 	int i = 0;
@@ -2940,15 +2949,13 @@ static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev)
 {
 	int ret = 0;
 	unsigned long flags;
-	struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
 	struct arm_smmu_device *smmu;
+	struct arm_smmu_master *master = dev_to_master(dev);
 	struct arm_smmu_domain *smmu_domain = to_smmu_domain(domain);
-	struct arm_smmu_master *master;
 
-	if (!fwspec)
+	if (!master)
 		return -ENOENT;
 
-	master = fwspec->iommu_priv;
 	smmu = master->smmu;
 
 	arm_smmu_detach_dev(master);
-- 
2.25.0