[PATCH v3 1/6] ARM/dma-mapping: Add arm_iommu_release_device()

[Lu Baolu]

It is like arm_iommu_detach_device() except it handles the special case
of being called under an iommu driver's release operation. In this case
the driver must have already detached the device from any attached
domain before calling this function.

Replace arm_iommu_detach_device() with arm_iommu_release_device() in the
release path of the ipmmu-vmsa driver.

The bonus is that it also removes a obstacle of arm_iommu_detach_device()
re-entering the iommu core during release_device. With this removed, the
iommu core code could be simplified a lot.

Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
---
 arch/arm/include/asm/dma-iommu.h |  1 +
 arch/arm/mm/dma-mapping.c        | 25 +++++++++++++++++++++++++
 drivers/iommu/ipmmu-vmsa.c       | 15 +++++++++++++--
 3 files changed, 39 insertions(+), 2 deletions(-)

diff --git a/arch/arm/include/asm/dma-iommu.h b/arch/arm/include/asm/dma-iommu.h
index fe9ef6f79e9c..ea7198a17861 100644
--- a/arch/arm/include/asm/dma-iommu.h
+++ b/arch/arm/include/asm/dma-iommu.h
@@ -31,6 +31,7 @@ void arm_iommu_release_mapping(struct dma_iommu_mapping *mapping);
 int arm_iommu_attach_device(struct device *dev,
 					struct dma_iommu_mapping *mapping);
 void arm_iommu_detach_device(struct device *dev);
+void arm_iommu_release_device(struct device *dev);
 
 #endif /* __KERNEL__ */
 #endif
diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index 8bc01071474a..96fa27f4a164 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -1682,6 +1682,31 @@ int arm_iommu_attach_device(struct device *dev,
 }
 EXPORT_SYMBOL_GPL(arm_iommu_attach_device);
 
+/**
+ * arm_iommu_release_device
+ * @dev: valid struct device pointer
+ *
+ * This is like arm_iommu_detach_device() except it handles the special
+ * case of being called under an iommu driver's release operation. In this
+ * case the driver must have already detached the device from any attached
+ * domain before calling this function.
+ */
+void arm_iommu_release_device(struct device *dev)
+{
+	struct dma_iommu_mapping *mapping;
+
+	mapping = to_dma_iommu_mapping(dev);
+	if (!mapping) {
+		dev_warn(dev, "Not attached\n");
+		return;
+	}
+
+	kref_put(&mapping->kref, release_iommu_mapping);
+	to_dma_iommu_mapping(dev) = NULL;
+	set_dma_ops(dev, NULL);
+}
+EXPORT_SYMBOL_GPL(arm_iommu_release_device);
+
 /**
  * arm_iommu_detach_device
  * @dev: valid struct device pointer
diff --git a/drivers/iommu/ipmmu-vmsa.c b/drivers/iommu/ipmmu-vmsa.c
index bdf1a4e5eae0..de9c74cf61a4 100644
--- a/drivers/iommu/ipmmu-vmsa.c
+++ b/drivers/iommu/ipmmu-vmsa.c
@@ -30,7 +30,7 @@
 #define arm_iommu_create_mapping(...)	NULL
 #define arm_iommu_attach_device(...)	-ENODEV
 #define arm_iommu_release_mapping(...)	do {} while (0)
-#define arm_iommu_detach_device(...)	do {} while (0)
+#define arm_iommu_release_device(...)	do {} while (0)
 #endif
 
 #define IPMMU_CTX_MAX		16U
@@ -820,7 +820,18 @@ static void ipmmu_probe_finalize(struct device *dev)
 
 static void ipmmu_release_device(struct device *dev)
 {
-	arm_iommu_detach_device(dev);
+	struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
+	struct ipmmu_vmsa_device *mmu = to_ipmmu(dev);
+	unsigned int i;
+
+	for (i = 0; i < fwspec->num_ids; ++i) {
+		unsigned int utlb = fwspec->ids[i];
+
+		ipmmu_imuctr_write(mmu, utlb, 0);
+		mmu->utlb_ctx[utlb] = IPMMU_CTX_INVALID;
+	}
+
+	arm_iommu_release_device(dev);
 }
 
 static struct iommu_group *ipmmu_find_group(struct device *dev)
-- 
2.34.1