of/pci: Add of_pci_dma_configure() to update DMA configuration

Add of_pci_dma_configure() to allow updating the DMA configuration of the
PCI device using the configuration from DT of the parent of the root bridge
device.  Use the newly added APIs pci_get/put_host_bridge_device() for
implementing this.

[bhelgaas: fold in fix for host bridges with no parent OF device]
Tested-by: Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com> (AMD Seattle)
Signed-off-by: Murali Karicheri <m-karicheri2@ti.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Rob Herring <robh+dt@kernel.org>
Acked-by: Will Deacon <will.deacon@arm.com>
CC: Joerg Roedel <joro@8bytes.org>
CC: Grant Likely <grant.likely@linaro.org>
CC: Russell King <linux@arm.linux.org.uk>
CC: Arnd Bergmann <arnd@arndb.de>

1 files changed, 21 insertions, 0 deletions

diff --git a/drivers/of/of_pci.c b/drivers/of/of_pci.c
index 62426d81a4d6..5751dc5b6494 100644
--- a/drivers/of/of_pci.c
+++ b/drivers/of/of_pci.c
@@ -2,6 +2,7 @@
 #include <linux/export.h>
 #include <linux/of.h>
 #include <linux/of_address.h>
+#include <linux/of_device.h>
 #include <linux/of_pci.h>
 #include <linux/slab.h>
 
@@ -116,6 +117,26 @@ int of_get_pci_domain_nr(struct device_node *node)
 }
 EXPORT_SYMBOL_GPL(of_get_pci_domain_nr);
 
+/**
+ * of_pci_dma_configure - Setup DMA configuration
+ * @dev: ptr to pci_dev struct of the PCI device
+ *
+ * Function to update PCI devices's DMA configuration using the same
+ * info from the OF node of host bridge's parent (if any).
+ */
+void of_pci_dma_configure(struct pci_dev *pci_dev)
+{
+	struct device *dev = &pci_dev->dev;
+	struct device *bridge = pci_get_host_bridge_device(pci_dev);
+
+	if (!bridge->parent)
+		return;
+
+	of_dma_configure(dev, bridge->parent->of_node);
+	pci_put_host_bridge_device(bridge);
+}
+EXPORT_SYMBOL_GPL(of_pci_dma_configure);
+
 #if defined(CONFIG_OF_ADDRESS)
 /**
  * of_pci_get_host_bridge_resources - Parse PCI host bridge resources from DT