[PATCH v15 12/12] of: Add plumbing for restricted DMA pool

[Claire Chang <tientzu@xxxxxxxxxxxx>]

If a device is not behind an IOMMU, we look up the device node and set
up the restricted DMA when the restricted-dma-pool is presented.

Signed-off-by: Claire Chang <tientzu@xxxxxxxxxxxx>
Tested-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>
Tested-by: Will Deacon <will@xxxxxxxxxx>
---
 drivers/of/address.c    | 33 +++++++++++++++++++++++++++++++++
 drivers/of/device.c     |  3 +++
 drivers/of/of_private.h |  6 ++++++
 3 files changed, 42 insertions(+)

diff --git a/drivers/of/address.c b/drivers/of/address.c
index 73ddf2540f3f..cdf700fba5c4 100644
--- a/drivers/of/address.c
+++ b/drivers/of/address.c
@@ -8,6 +8,7 @@
 #include <linux/logic_pio.h>
 #include <linux/module.h>
 #include <linux/of_address.h>
+#include <linux/of_reserved_mem.h>
 #include <linux/pci.h>
 #include <linux/pci_regs.h>
 #include <linux/sizes.h>
@@ -1022,6 +1023,38 @@ int of_dma_get_range(struct device_node *np, const 
struct bus_dma_region **map)
        of_node_put(node);
        return ret;
 }
+
+int of_dma_set_restricted_buffer(struct device *dev, struct device_node *np)
+{
+       struct device_node *node, *of_node = dev->of_node;
+       int count, i;
+
+       count = of_property_count_elems_of_size(of_node, "memory-region",
+                                               sizeof(u32));
+       /*
+        * If dev->of_node doesn't exist or doesn't contain memory-region, try
+        * the OF node having DMA configuration.
+        */
+       if (count <= 0) {
+               of_node = np;
+               count = of_property_count_elems_of_size(
+                       of_node, "memory-region", sizeof(u32));
+       }
+
+       for (i = 0; i < count; i++) {
+               node = of_parse_phandle(of_node, "memory-region", i);
+               /*
+                * There might be multiple memory regions, but only one
+                * restricted-dma-pool region is allowed.
+                */
+               if (of_device_is_compatible(node, "restricted-dma-pool") &&
+                   of_device_is_available(node))
+                       return of_reserved_mem_device_init_by_idx(dev, of_node,
+                                                                 i);
+       }
+
+       return 0;
+}
 #endif /* CONFIG_HAS_DMA */
 
 /**
diff --git a/drivers/of/device.c b/drivers/of/device.c
index 6cb86de404f1..e68316836a7a 100644
--- a/drivers/of/device.c
+++ b/drivers/of/device.c
@@ -165,6 +165,9 @@ int of_dma_configure_id(struct device *dev, struct 
device_node *np,
 
        arch_setup_dma_ops(dev, dma_start, size, iommu, coherent);
 
+       if (!iommu)
+               return of_dma_set_restricted_buffer(dev, np);
+
        return 0;
 }
 EXPORT_SYMBOL_GPL(of_dma_configure_id);
diff --git a/drivers/of/of_private.h b/drivers/of/of_private.h
index d9e6a324de0a..25cebbed5f02 100644
--- a/drivers/of/of_private.h
+++ b/drivers/of/of_private.h
@@ -161,12 +161,18 @@ struct bus_dma_region;
 #if defined(CONFIG_OF_ADDRESS) && defined(CONFIG_HAS_DMA)
 int of_dma_get_range(struct device_node *np,
                const struct bus_dma_region **map);
+int of_dma_set_restricted_buffer(struct device *dev, struct device_node *np);
 #else
 static inline int of_dma_get_range(struct device_node *np,
                const struct bus_dma_region **map)
 {
        return -ENODEV;
 }
+static inline int of_dma_set_restricted_buffer(struct device *dev,
+                                              struct device_node *np)
+{
+       return -ENODEV;
+}
 #endif
 
 #endif /* _LINUX_OF_PRIVATE_H */
-- 
2.32.0.288.g62a8d224e6-goog