From 1f9b32916b0859cda5ca40f785fbffd45b3e5a25 Mon Sep 17 00:00:00 2001
From: Mitchel Humpherys <mitchelh@codeaurora.org>
Date: Thu, 9 Jul 2015 16:59:02 -0700
Subject: [PATCH] iommu: Add iommu_trigger_fault

It can be useful to trigger an IOMMU fault during development and
debugging.  Add support to the IOMMU framework to do so.

Change-Id: I908c9f5b52c6abe937f031de546d290027ba64b5
Signed-off-by: Mitchel Humpherys <mitchelh@codeaurora.org>
---
 drivers/iommu/iommu.c | 15 +++++++++++++++
 include/linux/iommu.h |  7 +++++++
 2 files changed, 22 insertions(+)

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 9821a73c33a8..9959b48e6f18 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -886,6 +886,21 @@ void iommu_set_fault_handler(struct iommu_domain *domain,
 }
 EXPORT_SYMBOL_GPL(iommu_set_fault_handler);
 
+/**
+ * iommu_trigger_fault() - trigger an IOMMU fault
+ * @domain: iommu domain
+ *
+ * Triggers a fault on the device to which this domain is attached.
+ *
+ * This function should only be used for debugging purposes, for obvious
+ * reasons.
+ */
+void iommu_trigger_fault(struct iommu_domain *domain)
+{
+	if (domain->ops->trigger_fault)
+		domain->ops->trigger_fault(domain);
+}
+
 struct iommu_domain *iommu_domain_alloc(struct bus_type *bus)
 {
 	struct iommu_domain *domain;
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 2e5b071d82d0..520cc5b4dae1 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -116,6 +116,7 @@ enum iommu_attr {
  * @domain_get_attr: Query domain attributes
  * @domain_set_attr: Change domain attributes
  * @pgsize_bitmap: bitmap of supported page sizes
+ * @trigger_fault: trigger a fault on the device attached to an iommu domain
  */
 struct iommu_ops {
 	bool (*capable)(enum iommu_cap);
@@ -150,6 +151,7 @@ struct iommu_ops {
 	u32 (*domain_get_windows)(struct iommu_domain *domain);
 	int (*dma_supported)(struct iommu_domain *domain, struct device *dev,
 			     u64 mask);
+	void (*trigger_fault)(struct iommu_domain *domain);
 
 	unsigned long pgsize_bitmap;
 };
@@ -185,6 +187,7 @@ extern phys_addr_t iommu_iova_to_phys_hard(struct iommu_domain *domain,
 					   dma_addr_t iova);
 extern void iommu_set_fault_handler(struct iommu_domain *domain,
 			iommu_fault_handler_t handler, void *token);
+extern void iommu_trigger_fault(struct iommu_domain *domain);
 
 extern int iommu_attach_group(struct iommu_domain *domain,
 			      struct iommu_group *group);
@@ -374,6 +377,10 @@ static inline void iommu_set_fault_handler(struct iommu_domain *domain,
 {
 }
 
+static inline void iommu_trigger_fault(struct iommu_domain *domain)
+{
+}
+
 static inline int iommu_attach_group(struct iommu_domain *domain,
 				     struct iommu_group *group)
 {
-- 
2.11.0