2 files changed, 67 insertions, 0 deletions

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 2fb2963df553..9c35be4b333f 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -25,8 +25,59 @@
 #include <linux/errno.h>
 #include <linux/iommu.h>
 
+static ssize_t show_iommu_group(struct device *dev,
+                                struct device_attribute *attr, char *buf)
+{
+        unsigned int groupid;
+
+        if (iommu_device_group(dev, &groupid))
+                return 0;
+
+        return sprintf(buf, "%u", groupid);
+}
+static DEVICE_ATTR(iommu_group, S_IRUGO, show_iommu_group, NULL);
+
+static int add_iommu_group(struct device *dev, void *data)
+{
+        unsigned int groupid;
+
+        if (iommu_device_group(dev, &groupid) == 0)
+                return device_create_file(dev, &dev_attr_iommu_group);
+
+        return 0;
+}
+
+static int remove_iommu_group(struct device *dev)
+{
+        unsigned int groupid;
+
+        if (iommu_device_group(dev, &groupid) == 0)
+                device_remove_file(dev, &dev_attr_iommu_group);
+
+        return 0;
+}
+
+static int iommu_device_notifier(struct notifier_block *nb,
+                                 unsigned long action, void *data)
+{
+        struct device *dev = data;
+
+        if (action == BUS_NOTIFY_ADD_DEVICE)
+                return add_iommu_group(dev, NULL);
+        else if (action == BUS_NOTIFY_DEL_DEVICE)
+                return remove_iommu_group(dev);
+
+        return 0;
+}
+
+static struct notifier_block iommu_device_nb = {
+        .notifier_call = iommu_device_notifier,
+};
+
 static void iommu_bus_init(struct bus_type *bus, struct iommu_ops *ops)
 {
+        bus_register_notifier(bus, &iommu_device_nb);
+        bus_for_each_dev(bus, NULL, NULL, add_iommu_group);
 }
 
 /**
@@ -186,3 +237,12 @@ int iommu_unmap(struct iommu_domain *domain, unsigned long iova, int gfp_order)
         return domain->ops->unmap(domain, iova, gfp_order);
 }
 EXPORT_SYMBOL_GPL(iommu_unmap);
+
+int iommu_device_group(struct device *dev, unsigned int *groupid)
+{
+        if (iommu_present(dev->bus) && dev->bus->iommu_ops->device_group)
+                return dev->bus->iommu_ops->device_group(dev, groupid);
+
+        return -ENODEV;
+}
+EXPORT_SYMBOL_GPL(iommu_device_group);
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 432acc4c054d..93617e7779a1 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -61,6 +61,7 @@ struct iommu_ops {
                                     unsigned long iova);
         int (*domain_has_cap)(struct iommu_domain *domain,
                               unsigned long cap);
+        int (*device_group)(struct device *dev, unsigned int *groupid);
 };
 
 extern int bus_set_iommu(struct bus_type *bus, struct iommu_ops *ops);
@@ -81,6 +82,7 @@ extern int iommu_domain_has_cap(struct iommu_domain *domain,
                                 unsigned long cap);
 extern void iommu_set_fault_handler(struct iommu_domain *domain,
                                         iommu_fault_handler_t handler);
+extern int iommu_device_group(struct device *dev, unsigned int *groupid);
 
 /**
  * report_iommu_fault() - report about an IOMMU fault to the IOMMU framework
@@ -179,6 +181,11 @@ static inline void iommu_set_fault_handler(struct iommu_domain *domain,
 {
 }
 
+static inline int iommu_device_group(struct device *dev, unsigned int *groupid);
+{
+        return -ENODEV;
+}
+
 #endif /* CONFIG_IOMMU_API */
 
 #endif /* __LINUX_IOMMU_H */