[V4 PATCH 4/6] device property: Introduces device_dma_is_coherent()

[Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com>]

Currently, device drivers, which support both OF and ACPI,
need to call two separate APIs, of_dma_is_coherent() and
acpi_dma_is_coherent()) to determine device coherency attribute.

This patch simplifies this process by introducing a new device
property API, device_dma_is_coherent(), which calls the appropriate
interface based on the booting architecture.

Signed-off-by: Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com>
CC: Rafael J. Wysocki <rjw@rjwysocki.net>
---
 drivers/base/property.c  | 12 ++++++++++++
 include/linux/property.h |  2 ++
 2 files changed, 14 insertions(+)

diff --git a/drivers/base/property.c b/drivers/base/property.c
index 1d0b116..8123c6e 100644
--- a/drivers/base/property.c
+++ b/drivers/base/property.c
@@ -14,6 +14,7 @@
 #include <linux/export.h>
 #include <linux/kernel.h>
 #include <linux/of.h>
+#include <linux/of_address.h>
 #include <linux/property.h>
 
 /**
@@ -519,3 +520,14 @@ unsigned int device_get_child_node_count(struct device *dev)
 	return count;
 }
 EXPORT_SYMBOL_GPL(device_get_child_node_count);
+
+bool device_dma_is_coherent(struct device *dev)
+{
+	if (IS_ENABLED(CONFIG_OF) && dev->of_node)
+		return of_dma_is_coherent(dev->of_node);
+	else if (has_acpi_companion(dev))
+		return acpi_dma_is_coherent(acpi_node(dev->fwnode));
+
+	return false;
+}
+EXPORT_SYMBOL_GPL(device_dma_is_coherent);
diff --git a/include/linux/property.h b/include/linux/property.h
index de8bdf4..76ebde9 100644
--- a/include/linux/property.h
+++ b/include/linux/property.h
@@ -164,4 +164,6 @@ struct property_set {
 
 void device_add_property_set(struct device *dev, struct property_set *pset);
 
+bool device_dma_is_coherent(struct device *dev);
+
 #endif /* _LINUX_PROPERTY_H_ */
-- 
2.1.0