On 01/23/2015 06:41 PM, Bjorn Helgaas wrote:

On Fri, Jan 23, 2015 at 05:32:37PM -0500, Murali Karicheri wrote:

quoted

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.

Cc: Joerg Roedel<joro@8bytes.org>
Cc: Grant Likely<redacted>
Cc: Rob Herring<robh+dt@kernel.org>
Cc: Bjorn Helgaas<bhelgaas@google.com>
Cc: Will Deacon<redacted>
Cc: Russell King<redacted>
Cc: Arnd Bergmann<arnd@arndb.de>
Cc: Suravee Suthikulpanit<Suravee.Suthikulpanit@amd.com>

Signed-off-by: Murali Karicheri<redacted>
---
  drivers/of/of_pci.c    |   39 +++++++++++++++++++++++++++++++++++++++
  include/linux/of_pci.h |   12 ++++++++++++
  2 files changed, 51 insertions(+)

diff --git a/drivers/of/of_pci.c b/drivers/of/of_pci.c
index 88471d3..34878c9 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>

@@ -229,6 +230,44 @@ parse_failed:
  	return err;
  }
  EXPORT_SYMBOL_GPL(of_pci_get_host_bridge_resources);
+
+/**
+ * of_get_pci_root_bridge_parent - get the OF node of the root bridge's parent
+ * @dev: ptr to pci_dev struct of the pci device
+ *
+ * This function will traverse the bus up to the root bus starting with
+ * the child and return the OF node ptr to root bridge device's parent device.
+ */
+struct device_node *of_get_pci_root_bridge_parent(struct pci_dev *dev)

I'm not an OF person, but this interface seems like it might be too
special-purpose.  Maybe it would be enough to add
"of_get_pci_root_bridge()", and the caller could do this:

     struct device *bridge = of_get_pci_root_bridge(dev);
     struct device_node *parent_np = bridge->parent->of_node;

Also, the name "of_get_..." suggests that it increments a refcount, as
of_get_parent() does.  But you aren't doing anything with the refcount.

But I guess an "of_get_pci_root_bridge()" isn't doing anything OF-related,
so maybe we should just add a "pci_get_host_bridge(struct pci_dev *)"
to PCI instead.

Bjorn,

Thanks for the comment.

I think adding pci_get_host_bridge() is a good idea. There is already 
similar function in host-bridge.c. I have added this function re-using 
existing function find_pci_root_bus(). See the incremental diff below 
after this change. Does this look good?

diff --git a/drivers/of/of_pci.c b/drivers/of/of_pci.c
index 34878c9..77b15b5 100644
--- a/drivers/of/of_pci.c
+++ b/drivers/of/of_pci.c

@@ -232,26 +232,6 @@ parse_failed:
  EXPORT_SYMBOL_GPL(of_pci_get_host_bridge_resources);

  /**
- * of_get_pci_root_bridge_parent - get the OF node of the root bridge's 

parent
- * @dev: ptr to pci_dev struct of the pci device
- *
- * This function will traverse the bus up to the root bus starting with
- * the child and return the OF node ptr to root bridge device's parent 
device.
- */
-struct device_node *of_get_pci_root_bridge_parent(struct pci_dev *dev)
-{
-       struct pci_bus *bus = dev->bus;
-       struct device *bridge;
-
-       while (!pci_is_root_bus(bus))
-               bus = bus->parent;
-       bridge = bus->bridge;
-
-       return bridge->parent->of_node;
-}
-EXPORT_SYMBOL_GPL(of_get_pci_root_bridge_parent);
-
-/**
   * of_pci_dma_configure - Setup DMA configuration
   * @dev: ptr to pci_dev struct of the pci device
   *

@@ -261,10 +241,9 @@ EXPORT_SYMBOL_GPL(of_get_pci_root_bridge_parent);
  void of_pci_dma_configure(struct pci_dev *pci_dev)
  {
         struct device *dev = &pci_dev->dev;
-       struct device_node *parent_np;
+       struct device *bridge = pci_get_host_bridge(pci_dev);

-       parent_np = of_get_pci_root_bridge_parent(pci_dev);
-       of_dma_configure(dev, parent_np);
+       of_dma_configure(dev, bridge->parent->of_node);
  }
  EXPORT_SYMBOL_GPL(of_pci_dma_configure);

diff --git a/drivers/pci/host-bridge.c b/drivers/pci/host-bridge.c
index 0e5f3c9..9803aa6 100644
--- a/drivers/pci/host-bridge.c
+++ b/drivers/pci/host-bridge.c

@@ -23,6 +23,13 @@ static struct pci_host_bridge 

*find_pci_host_bridge(struct pci_bus *bus)
         return to_pci_host_bridge(root_bus->bridge);
  }

+struct device *pci_get_host_bridge(struct pci_dev *dev)
+{
+       struct pci_bus *root_bus = find_pci_root_bus(dev->bus);
+
+       return root_bus->bridge;
+}
+
  void pci_set_host_bridge_release(struct pci_host_bridge *bridge,
                                  void (*release_fn)(struct 
pci_host_bridge *),
                                  void *release_data)

diff --git a/include/linux/pci.h b/include/linux/pci.h
index 9603094..5bcdfa6 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h

@@ -513,6 +513,8 @@ static inline struct pci_dev 

*pci_upstream_bridge(struct pci_dev *dev)
         return dev->bus->self;
  }

+struct device *pci_get_host_bridge(struct pci_dev *dev);
+
  #ifdef CONFIG_PCI_MSI
  static inline bool pci_dev_msi_enabled(struct pci_dev *pci_dev)
  {

@@ -1823,6 +1825,7 @@ int pci_vpd_find_tag(const u8 *buf, unsigned int 

off, unsigned int len, u8 rdt);
  int pci_vpd_find_info_keyword(const u8 *buf, unsigned int off,
                               unsigned int len, const char *kw);

  /* PCI <-> OF binding helpers */
  #ifdef CONFIG_OF
  struct device_node;

Bjorn

quoted

+{
+	struct pci_bus *bus = dev->bus;
+	struct device *bridge;
+
+	while (!pci_is_root_bus(bus))
+		bus = bus->parent;
+	bridge = bus->bridge;
+
+	return bridge->parent->of_node;
+}
+EXPORT_SYMBOL_GPL(of_get_pci_root_bridge_parent);
+
+/**
+ * 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 root host bridge's parent.
+ */
+void of_pci_dma_configure(struct pci_dev *pci_dev)
+{
+	struct device *dev =&pci_dev->dev;
+	struct device_node *parent_np;
+
+	parent_np = of_get_pci_root_bridge_parent(pci_dev);
+	of_dma_configure(dev, parent_np);
+}
+EXPORT_SYMBOL_GPL(of_pci_dma_configure);
+
  #endif /* CONFIG_OF_ADDRESS */

  #ifdef CONFIG_PCI_MSI

diff --git a/include/linux/of_pci.h b/include/linux/of_pci.h
index ce0e5ab..0465a2a 100644
--- a/include/linux/of_pci.h
+++ b/include/linux/of_pci.h

@@ -16,6 +16,8 @@ int of_pci_get_devfn(struct device_node *np);
  int of_irq_parse_and_map_pci(const struct pci_dev *dev, u8 slot, u8 pin);
  int of_pci_parse_bus_range(struct device_node *node, struct resource *res);
  int of_get_pci_domain_nr(struct device_node *node);
+struct device_node *of_get_pci_root_bridge_parent(struct pci_dev *dev);
+void of_pci_dma_configure(struct pci_dev *pci_dev);
  #else
  static inline int of_irq_parse_pci(const struct pci_dev *pdev, struct of_phandle_args *out_irq)
  {

@@ -50,6 +52,16 @@ of_get_pci_domain_nr(struct device_node *node)
  {
  	return -1;
  }
+
+static inline struct device_node
+*of_get_pci_root_bridge_parent(struct pci_dev *dev)
+{
+	return NULL;
+}
+
+static inline void of_pci_dma_configure(struct pci_dev *pci_dev)
+{
+}
  #endif

  #if defined(CONFIG_OF_ADDRESS)
--

1.7.9.5

-- 
Murali Karicheri
Linux Kernel, Texas Instruments