[XEN][RFC PATCH v2 07/12] xen/smmu: Add remove_device callback for smmu_iommu ops

[Vikram Garhwal <fnu.vikram@xxxxxxxxxx>]

Add remove_device callback for removing the device entry from smmu-master using
 following steps:
    1. Find if SMMU master exists for the device node.
    2. Remove the SMMU master

Signed-off-by: Vikram Garhwal <fnu.vikram@xxxxxxxxxx>
---
 xen/drivers/passthrough/device_tree.c | 30 ++++++++++++++++++++++++++++++
 xen/include/xen/iommu.h               |  2 ++
 2 files changed, 32 insertions(+)

diff --git a/xen/drivers/passthrough/device_tree.c 
b/xen/drivers/passthrough/device_tree.c
index 98f2aa0..9d9eed8 100644
--- a/xen/drivers/passthrough/device_tree.c
+++ b/xen/drivers/passthrough/device_tree.c
@@ -127,6 +127,36 @@ int iommu_release_dt_devices(struct domain *d)
     return 0;
 }
 
+int iommu_remove_dt_device(struct dt_device_node *np)
+{
+    const struct iommu_ops *ops = iommu_get_ops();
+    struct device *dev = dt_to_dev(np);
+    int rc;
+
+    if ( !ops )
+        return -EOPNOTSUPP;
+
+    if ( iommu_dt_device_is_assigned(np) )
+        return -EPERM;
+
+    /*
+     * The driver which supports generic IOMMU DT bindings must have
+     * these callback implemented.
+     */
+    if ( !ops->remove_device )
+        return -EOPNOTSUPP;
+
+    /*
+     * Remove master device from the IOMMU if latter is present and available.
+     */
+    rc = ops->remove_device(0, dev);
+
+    if ( rc == 0 )
+        iommu_fwspec_free(dev);
+
+    return rc;
+}
+
 int iommu_add_dt_device(struct dt_device_node *np)
 {
     const struct iommu_ops *ops = iommu_get_ops();
diff --git a/xen/include/xen/iommu.h b/xen/include/xen/iommu.h
index 6b2cdff..c4d5d12 100644
--- a/xen/include/xen/iommu.h
+++ b/xen/include/xen/iommu.h
@@ -215,6 +215,8 @@ int iommu_release_dt_devices(struct domain *d);
  */
 int iommu_add_dt_device(struct dt_device_node *np);
 
+int iommu_remove_dt_device(struct dt_device_node *np);
+
 int iommu_do_dt_domctl(struct xen_domctl *, struct domain *,
                        XEN_GUEST_HANDLE_PARAM(xen_domctl_t));
 
-- 
2.7.4