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.
For the architectures which are fully dma coherent and don't need per device
property, it can enable CONFIG_ARCH_IS_DMA_COHERENT config option which
enables DMA coherent for all devices by default.
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Russell King <linux@xxxxxxxxxxxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Olof Johansson <olof@xxxxxxxxx>
Cc: Grant Likely <grant.likely@xxxxxxxxxx>
Cc: Rob Herring <robh+dt@xxxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Linus Walleij <linus.walleij@xxxxxxxxxx>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@xxxxxx>
---
drivers/of/platform.c | 31 +++++++++++++++++++++++++++++++
include/linux/of_platform.h | 6 ++++++
2 files changed, 37 insertions(+)
diff --git a/drivers/of/platform.c b/drivers/of/platform.c
index 2265a55..bd080db 100644
--- a/drivers/of/platform.c
+++ b/drivers/of/platform.c
@@ -570,4 +570,35 @@ 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.
+ */
+#ifndef CONFIG_ARCH_IS_DMA_COHERENT
+bool of_dma_is_coherent(struct device_node *np)
+{
+ struct device_node *node = np;
+
+ while (node) {
+ if (of_property_read_bool(node, "dma-coherent")) {
+ of_node_put(node);
+ return true;
+ }
+ node = of_get_next_parent(node);
+ }
+ return false;
+}
+EXPORT_SYMBOL_GPL(of_dma_is_coherent);
+#else
+inline bool of_dma_is_coherent(struct device_node *np)
+{
+ /* ARCH is fully dma coherent and don't need per device control */
+ return true;
+}
+EXPORT_SYMBOL_GPL(of_dma_is_coherent);
+#endif
#endif /* CONFIG_OF_ADDRESS */
diff --git a/include/linux/of_platform.h b/include/linux/of_platform.h
index ba7d3dc..48e0748 100644
--- a/include/linux/of_platform.h
+++ b/include/linux/of_platform.h
@@ -74,6 +74,7 @@ extern int of_platform_populate(struct device_node *root,
struct device *parent);
extern int of_dma_get_range(struct device_node *np, dma_addr_t *dma_addr,
phys_addr_t *paddr, phys_addr_t *size);
+extern bool of_dma_is_coherent(struct device_node *np);
#else
static inline int of_platform_populate(struct device_node *root,
const struct of_device_id *matches,
@@ -88,6 +89,11 @@ static inline int of_dma_get_range(struct device_node *np, dma_addr_t *dma_addr,
{
return -ENODEV;
}
+
+static inline bool of_dma_is_coherent(struct device_node *np)
+{
+ return false;
+}
#endif
#endif /* _LINUX_OF_PLATFORM_H */
--
1.7.9.5
--
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