iommu: Make .release_device optional

Many drivers do nothing meaningful for .release_device, and it's neatly
abstracted to just two callsites in the core code, so let's make it
optional to implement.

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/bda9d3eb4527eac8f6544a15067e2529cca54a2e.1655822151.git.robin.murphy@arm.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

Author: rmurphy-arm

drivers/iommu/fsl_pamu_domain.c

@@ -447,15 +447,10 @@ static struct iommu_device *fsl_pamu_probe_device(struct device *dev)
 	return &pamu_iommu;
 }
 
-static void fsl_pamu_release_device(struct device *dev)
-{
-}
-
 static const struct iommu_ops fsl_pamu_ops = {
 	.capable	= fsl_pamu_capable,
 	.domain_alloc	= fsl_pamu_domain_alloc,
 	.probe_device	= fsl_pamu_probe_device,
-	.release_device	= fsl_pamu_release_device,
 	.device_group   = fsl_pamu_device_group,
 	.default_domain_ops = &(const struct iommu_domain_ops) {
 		.attach_dev	= fsl_pamu_attach_device,

drivers/iommu/iommu.c

@@ -259,7 +259,8 @@ static int __iommu_probe_device(struct device *dev, struct list_head *group_list
 	return 0;
 
 out_release:
-	ops->release_device(dev);
+	if (ops->release_device)
+		ops->release_device(dev);
 
 out_module_put:
 	module_put(ops->owner);
@@ -337,7 +338,8 @@ void iommu_release_device(struct device *dev)
 	iommu_device_unlink(dev->iommu->iommu_dev, dev);
 
 	ops = dev_iommu_ops(dev);
-	ops->release_device(dev);
+	if (ops->release_device)
+		ops->release_device(dev);
 
 	iommu_group_remove_device(dev);
 	module_put(ops->owner);

drivers/iommu/msm_iommu.c

@@ -394,10 +394,6 @@ static struct iommu_device *msm_iommu_probe_device(struct device *dev)
 	return &iommu->iommu;
 }
 
-static void msm_iommu_release_device(struct device *dev)
-{
-}
-
 static int msm_iommu_attach_dev(struct iommu_domain *domain, struct device *dev)
 {
 	int ret = 0;
@@ -677,7 +673,6 @@ irqreturn_t msm_iommu_fault_handler(int irq, void *dev_id)
 static struct iommu_ops msm_iommu_ops = {
 	.domain_alloc = msm_iommu_domain_alloc,
 	.probe_device = msm_iommu_probe_device,
-	.release_device = msm_iommu_release_device,
 	.device_group = generic_device_group,
 	.pgsize_bitmap = MSM_IOMMU_PGSIZES,
 	.of_xlate = qcom_iommu_of_xlate,

drivers/iommu/sun50i-iommu.c

@@ -738,8 +738,6 @@ static struct iommu_device *sun50i_iommu_probe_device(struct device *dev)
 	return &iommu->iommu;
 }
 
-static void sun50i_iommu_release_device(struct device *dev) {}
-
 static struct iommu_group *sun50i_iommu_device_group(struct device *dev)
 {
 	struct sun50i_iommu *iommu = sun50i_iommu_from_dev(dev);
@@ -764,7 +762,6 @@ static const struct iommu_ops sun50i_iommu_ops = {
 	.domain_alloc	= sun50i_iommu_domain_alloc,
 	.of_xlate	= sun50i_iommu_of_xlate,
 	.probe_device	= sun50i_iommu_probe_device,
-	.release_device	= sun50i_iommu_release_device,
 	.default_domain_ops = &(const struct iommu_domain_ops) {
 		.attach_dev	= sun50i_iommu_attach_device,
 		.detach_dev	= sun50i_iommu_detach_device,

drivers/iommu/tegra-gart.c

@@ -246,10 +246,6 @@ static struct iommu_device *gart_iommu_probe_device(struct device *dev)
 	return &gart_handle->iommu;
 }
 
-static void gart_iommu_release_device(struct device *dev)
-{
-}
-
 static int gart_iommu_of_xlate(struct device *dev,
 			       struct of_phandle_args *args)
 {
@@ -273,7 +269,6 @@ static void gart_iommu_sync(struct iommu_domain *domain,
 static const struct iommu_ops gart_iommu_ops = {
 	.domain_alloc	= gart_iommu_domain_alloc,
 	.probe_device	= gart_iommu_probe_device,
-	.release_device	= gart_iommu_release_device,
 	.device_group	= generic_device_group,
 	.pgsize_bitmap	= GART_IOMMU_PGSIZES,
 	.of_xlate	= gart_iommu_of_xlate,

drivers/iommu/tegra-smmu.c

@@ -864,8 +864,6 @@ static struct iommu_device *tegra_smmu_probe_device(struct device *dev)
 	return &smmu->iommu;
 }
 
-static void tegra_smmu_release_device(struct device *dev) {}
-
 static const struct tegra_smmu_group_soc *
 tegra_smmu_find_group(struct tegra_smmu *smmu, unsigned int swgroup)
 {
@@ -966,7 +964,6 @@ static int tegra_smmu_of_xlate(struct device *dev,
 static const struct iommu_ops tegra_smmu_ops = {
 	.domain_alloc = tegra_smmu_domain_alloc,
 	.probe_device = tegra_smmu_probe_device,
-	.release_device = tegra_smmu_release_device,
 	.device_group = tegra_smmu_device_group,
 	.of_xlate = tegra_smmu_of_xlate,
 	.pgsize_bitmap = SZ_4K,