This patch adds a new API "device_connection_find_by_graph()" to
find device connection by using graph.
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx>
---
Documentation/driver-api/device_connection.rst | 4 +--
drivers/base/devcon.c | 43 ++++++++++++++++++++++++++
include/linux/device.h | 2 ++
3 files changed, 47 insertions(+), 2 deletions(-)
diff --git a/Documentation/driver-api/device_connection.rst b/Documentation/driver-api/device_connection.rst
index affbc556..2e2d26f 100644
--- a/Documentation/driver-api/device_connection.rst
+++ b/Documentation/driver-api/device_connection.rst
@@ -19,7 +19,7 @@ Device connections alone do not create a dependency between the two devices.
They are only descriptions which are not tied to either of the devices directly.
A dependency between the two devices exists only if one of the two endpoint
devices requests a reference to the other. The descriptions themselves can be
-defined in firmware (not yet supported) or they can be built-in.
+defined in firmware or they can be built-in.
Usage
-----
@@ -40,4 +40,4 @@ API
---
.. kernel-doc:: drivers/base/devcon.c
- : functions: device_connection_find_match device_connection_find device_connection_add device_connection_remove
+ : functions: device_connection_find_match device_connection_find device_connection_add device_connection_remove device_connection_find_by_graph
diff --git a/drivers/base/devcon.c b/drivers/base/devcon.c
index d427e80..5a0da33 100644
--- a/drivers/base/devcon.c
+++ b/drivers/base/devcon.c
@@ -7,6 +7,7 @@
*/
#include <linux/device.h>
+#include <linux/property.h>
static DEFINE_MUTEX(devcon_lock);
static LIST_HEAD(devcon_list);
@@ -134,3 +135,45 @@ void device_connection_remove(struct device_connection *con)
mutex_unlock(&devcon_lock);
}
EXPORT_SYMBOL_GPL(device_connection_remove);
+
+static int generic_graph_match(struct device *dev, void *fwnode)
+{
+ return dev->fwnode == fwnode;
+}
+
+/**
+ * device_connection_find_by_graph - Find two devices connected together
+ * @dev: Device to find connected device
+ * @port: identifier of the @dev port node
+ * @endpoint: identifier of the @dev endpoint node
+ *
+ * Find a connection with @port and @endpoint by using graph between @dev and
+ * another device. On success returns handle to the device that is connected
+ * to @dev, with the reference count for the found device incremented. Returns
+ * NULL if no matching connection was found, or ERR_PTR(-EPROBE_DEFER) when
+ * a connection was found but the other device has not been enumerated yet.
+ */
+struct device *device_connection_find_by_graph(struct device *dev, u32 port,
+ u32 endpoint)
+{
+ struct bus_type *bus;
+ struct fwnode_handle *remote;
+ struct device *conn;
+
+ remote = fwnode_graph_get_remote_node(dev_fwnode(dev), port, endpoint);
+ if (!remote)
+ return NULL;
+
+ for (bus = generic_match_buses[0]; bus; bus++) {
+ conn = bus_find_device(bus, NULL, remote, generic_graph_match);
+ if (conn)
+ return conn;
+ }
+
+ /*
+ * We only get called if a connection was found, tell the caller to
+ * wait for the other device to show up.
+ */
+ return ERR_PTR(-EPROBE_DEFER);
+}
+EXPORT_SYMBOL_GPL(device_connection_find_by_graph);
diff --git a/include/linux/device.h b/include/linux/device.h
index 0059b99..58f8544 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -751,6 +751,8 @@ void *device_connection_find_match(struct device *dev, const char *con_id,
void device_connection_add(struct device_connection *con);
void device_connection_remove(struct device_connection *con);
+struct device *device_connection_find_by_graph(struct device *dev, u32 port,
+ u32 endpoint);
/**
* enum device_link_state - Device link states.
--
1.9.1
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