of: introduce of_dma_is_coherent() helper

The of_dma_is_coherent() helper parses the given DT device
node to see if the "dma-coherent" property is supported and
returns true or false accordingly.

If the arch is always coherent or always noncoherent, then the default
DMA ops has to be specified accordingly.

Cc: Greg Kroah-Hartman <[email protected]>
Cc: Russell King <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Olof Johansson <[email protected]>
Cc: Grant Likely <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: Linus Walleij <[email protected]>
Reviewed-by: Rob Herring <[email protected]>
Signed-off-by: Santosh Shilimkar <[email protected]>
Signed-off-by: Grygorii Strashko <[email protected]>

diff --git a/drivers/of/address.c b/drivers/of/address.c
index c54baee87d93aba6e3e5a5879251dae750a36dad..d244b2859aac631b17dca4ecc16920e83fdc51a5 100644 (file)
--- a/drivers/of/address.c
+++ b/drivers/of/address.c
@@ -808,3 +808,26 @@ out:
        return ret;
 }
 EXPORT_SYMBOL_GPL(of_dma_get_range);
+
+/**
+ * of_dma_is_coherent - Check if device is coherent
+ * @np:        device node
+ *
+ * It returns true if "dma-coherent" property was found
+ * for this device in DT.
+ */
+bool of_dma_is_coherent(struct device_node *np)
+{
+       struct device_node *node = of_node_get(np);
+
+       while (node) {
+               if (of_property_read_bool(node, "dma-coherent")) {
+                       of_node_put(node);
+                       return true;
+               }
+               node = of_get_next_parent(node);
+       }
+       of_node_put(node);
+       return false;
+}
+EXPORT_SYMBOL_GPL(of_dma_is_coherent);
\ No newline at end of file

diff --git a/include/linux/of_address.h b/include/linux/of_address.h
index 4d7b325af2ca49f68096b3d8e41ad5b4f6818dd0..839a3521b28ebfd7e941e29f32e67bc0fd816886 100644 (file)
--- a/include/linux/of_address.h
+++ b/include/linux/of_address.h
@@ -65,6 +65,7 @@ extern struct of_pci_range *of_pci_range_parser_one(
                                        struct of_pci_range *range);
 extern int of_dma_get_range(struct device_node *np, u64 *dma_addr,
                                u64 *paddr, u64 *size);
+extern bool of_dma_is_coherent(struct device_node *np);
 #else /* CONFIG_OF_ADDRESS */
 static inline struct device_node *of_find_matching_node_by_address(
                                        struct device_node *from,
@@ -98,6 +99,11 @@ static inline int of_dma_get_range(struct device_node *np, u64 *dma_addr,
 {
        return -ENODEV;
 }
+
+static inline bool of_dma_is_coherent(struct device_node *np)
+{
+       return false;
+}
 #endif /* CONFIG_OF_ADDRESS */
 
 #ifdef CONFIG_OF