usb: Iterator for ports

Introducing usb_for_each_port(). It works the same way as
usb_for_each_dev(), but instead of going through every USB
device in the system, it walks through the USB ports in the
system.

Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Link: https://lore.kernel.org/r/20210407065555.88110-4-heikki.krogerus@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/core/usb.c b/drivers/usb/core/usb.c
index 2ce3667..62368c4 100644 (file)
--- a/drivers/usb/core/usb.c
+++ b/drivers/usb/core/usb.c
@@ -398,6 +398,52 @@ int usb_for_each_dev(void *data, int (*fn)(struct usb_device *, void *))
 }
 EXPORT_SYMBOL_GPL(usb_for_each_dev);
 
+struct each_hub_arg {
+       void *data;
+       int (*fn)(struct device *, void *);
+};
+
+static int __each_hub(struct usb_device *hdev, void *data)
+{
+       struct each_hub_arg *arg = (struct each_hub_arg *)data;
+       struct usb_hub *hub;
+       int ret = 0;
+       int i;
+
+       hub = usb_hub_to_struct_hub(hdev);
+       if (!hub)
+               return 0;
+
+       mutex_lock(&usb_port_peer_mutex);
+
+       for (i = 0; i < hdev->maxchild; i++) {
+               ret = arg->fn(&hub->ports[i]->dev, arg->data);
+               if (ret)
+                       break;
+       }
+
+       mutex_unlock(&usb_port_peer_mutex);
+
+       return ret;
+}
+
+/**
+ * usb_for_each_port - interate over all USB ports in the system
+ * @data: data pointer that will be handed to the callback function
+ * @fn: callback function to be called for each USB port
+ *
+ * Iterate over all USB ports and call @fn for each, passing it @data. If it
+ * returns anything other than 0, we break the iteration prematurely and return
+ * that value.
+ */
+int usb_for_each_port(void *data, int (*fn)(struct device *, void *))
+{
+       struct each_hub_arg arg = {data, fn};
+
+       return usb_for_each_dev(&arg, __each_hub);
+}
+EXPORT_SYMBOL_GPL(usb_for_each_port);
+
 /**
  * usb_release_dev - free a usb device structure when all users of it are finished.
  * @dev: device that's been disconnected

diff --git a/include/linux/usb.h b/include/linux/usb.h
index ddd2f5b..eaae242 100644 (file)
--- a/include/linux/usb.h
+++ b/include/linux/usb.h
@@ -882,6 +882,15 @@ extern struct usb_host_interface *usb_find_alt_setting(
                unsigned int iface_num,
                unsigned int alt_num);
 
+#if IS_REACHABLE(CONFIG_USB)
+int usb_for_each_port(void *data, int (*fn)(struct device *, void *));
+#else
+static inline int usb_for_each_port(void *data, int (*fn)(struct device *, void *))
+{
+       return 0;
+}
+#endif
+
 /* port claiming functions */
 int usb_hub_claim_port(struct usb_device *hdev, unsigned port1,
                struct usb_dev_state *owner);