[PATCH v7 3/5] iommu/of: Add msi address regions reservation helper

[Shameer Kolothum]

From: John Garry <john.garry at huawei.com>

On some platforms msi-controller address regions have to be excluded
from normal IOVA allocation in that they are detected and decoded in
a HW specific way by system components and so they cannot be considered
normal IOVA address space.

Add a helper function that retrieves msi address regions through device
tree msi mapping, so that these regions will not be translated by IOMMU
and will be excluded from IOVA allocations.

Signed-off-by: John Garry <john.garry at huawei.com>
Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi at huawei.com>
---
 drivers/iommu/of_iommu.c | 117 +++++++++++++++++++++++++++++++++++++++++++++++
 include/linux/of_iommu.h |  10 ++++
 2 files changed, 127 insertions(+)

diff --git a/drivers/iommu/of_iommu.c b/drivers/iommu/of_iommu.c
index 8cb6082..f2d1a76 100644
--- a/drivers/iommu/of_iommu.c
+++ b/drivers/iommu/of_iommu.c
@@ -21,6 +21,7 @@
 #include <linux/iommu.h>
 #include <linux/limits.h>
 #include <linux/of.h>
+#include <linux/of_address.h>
 #include <linux/of_iommu.h>
 #include <linux/of_pci.h>
 #include <linux/slab.h>
@@ -246,6 +247,122 @@ const struct iommu_ops *of_iommu_configure(struct device *dev,
 	return ops;
 }
 
+/**
+ * of_iommu_msi_get_resv_regions - Reserved region driver helper
+ * @dev: Device from iommu_get_resv_regions()
+ * @list: Reserved region list from iommu_get_resv_regions()
+ *
+ * Returns: Number of reserved regions on success (0 if no associated
+ *          msi parent), appropriate error value otherwise.
+ */
+int of_iommu_msi_get_resv_regions(struct device *dev, struct list_head *head)
+{
+	int prot = IOMMU_WRITE | IOMMU_NOEXEC | IOMMU_MMIO;
+	struct iommu_resv_region *region;
+	struct device_node *np;
+	struct resource res;
+	int i, resv = 0, mappings = 0;
+
+	if (dev_is_pci(dev)) {
+		struct device *dma_dev, *bridge;
+		struct of_phandle_args iommu_spec;
+		struct pci_dev *pdev = to_pci_dev(dev);
+		int err, count;
+		u32 rid, map_mask;
+		const __be32 *msi_map;
+
+		bridge = pci_get_host_bridge_device(pdev);
+		dma_dev = bridge->parent;
+		pci_put_host_bridge_device(bridge);
+
+		if (!dma_dev->of_node)
+			return -ENODEV;
+
+		iommu_spec.args_count = 1;
+		np = iommu_spec.np = dma_dev->of_node;
+		pci_for_each_dma_alias(pdev, __get_pci_rid, &iommu_spec);
+
+		rid = iommu_spec.args[0];
+		if (!of_property_read_u32(np, "msi-map-mask", &map_mask))
+			rid &= map_mask;
+
+		msi_map = of_get_property(np, "msi-map", NULL);
+		if (!msi_map)
+			return -ENODEV;
+
+		mappings = of_count_phandle_with_args(np, "msi-map", NULL) / 4;
+
+		for (i = 0, count = mappings; i < count; i++, msi_map += 4) {
+			struct device_node *msi_node;
+			u32 rid_base, rid_len, phandle;
+
+			rid_base = be32_to_cpup(msi_map + 0);
+			phandle = be32_to_cpup(msi_map + 1);
+			rid_len = be32_to_cpup(msi_map + 3);
+
+			/* check rid is within range */
+			if (rid < rid_base || rid >= rid_base + rid_len) {
+				mappings--;
+				continue;
+			}
+
+			msi_node = of_find_node_by_phandle(phandle);
+			if (!msi_node)
+				return -ENODEV;
+
+			err = of_address_to_resource(msi_node, 0, &res);
+			of_node_put(msi_node);
+			if (err)
+				return err;
+
+			region = iommu_alloc_resv_region(res.start,
+							 resource_size(&res),
+							 prot, IOMMU_RESV_MSI);
+			if (region) {
+				list_add_tail(&region->list, head);
+				resv++;
+			}
+		}
+	} else if (dev->of_node) {
+		struct device_node *msi_np;
+		int index = 0;
+		int tuples;
+
+		np = dev->of_node;
+
+		tuples = of_count_phandle_with_args(np, "msi-parent", NULL);
+
+		while (index < tuples) {
+			int msi_cells = 0;
+			int err;
+
+			msi_np = of_parse_phandle(np, "msi-parent", index);
+			if (!msi_np)
+				return -ENODEV;
+
+			of_property_read_u32(msi_np, "#msi-cells", &msi_cells);
+
+			err = of_address_to_resource(msi_np, 0, &res);
+			of_node_put(msi_np);
+			if (err)
+				return err;
+
+			mappings++;
+
+			region = iommu_alloc_resv_region(res.start,
+							 resource_size(&res),
+							 prot, IOMMU_RESV_MSI);
+			if (region) {
+				list_add_tail(&region->list, head);
+				resv++;
+			}
+			index += 1 + msi_cells;
+		}
+	}
+
+	return (resv == mappings) ? resv : -ENODEV;
+}
+
 static int __init of_iommu_init(void)
 {
 	struct device_node *np;
diff --git a/include/linux/of_iommu.h b/include/linux/of_iommu.h
index 13394ac..9267772 100644
--- a/include/linux/of_iommu.h
+++ b/include/linux/of_iommu.h
@@ -14,6 +14,9 @@ extern int of_get_dma_window(struct device_node *dn, const char *prefix,
 extern const struct iommu_ops *of_iommu_configure(struct device *dev,
 					struct device_node *master_np);
 
+extern int of_iommu_msi_get_resv_regions(struct device *dev,
+					struct list_head *head);
+
 #else
 
 static inline int of_get_dma_window(struct device_node *dn, const char *prefix,
@@ -29,6 +32,13 @@ static inline const struct iommu_ops *of_iommu_configure(struct device *dev,
 	return NULL;
 }
 
+static int of_iommu_msi_get_resv_regions(struct device *dev,
+					struct list_head *head)
+{
+	return -ENODEV;
+}
+
+
 #endif	/* CONFIG_OF_IOMMU */
 
 extern struct of_device_id __iommu_of_table;
-- 
1.9.1