[PATCH v10 1/6] usb: gadget: udc: core: Introduce check_config to verify USB configuration

[Wesley Cheng]

Some UDCs may have constraints on how many high bandwidth endpoints it can
support in a certain configuration.  This API allows for the composite
driver to pass down the total number of endpoints to the UDC so it can verify
it has the required resources to support the configuration.

Signed-off-by: Wesley Cheng <wcheng@xxxxxxxxxxxxxx>
---
 drivers/usb/gadget/udc/core.c | 25 +++++++++++++++++++++++++
 include/linux/usb/gadget.h    |  5 +++++
 2 files changed, 30 insertions(+)

diff --git a/drivers/usb/gadget/udc/core.c b/drivers/usb/gadget/udc/core.c
index b7f0b1e..e33ae2d 100644
--- a/drivers/usb/gadget/udc/core.c
+++ b/drivers/usb/gadget/udc/core.c
@@ -1003,6 +1003,31 @@ int usb_gadget_ep_match_desc(struct usb_gadget *gadget,
 }
 EXPORT_SYMBOL_GPL(usb_gadget_ep_match_desc);
 
+/**
+ * usb_gadget_check_config - checks if the UDC can support the number of eps
+ * @gadget: controller to check the USB configuration
+ * @ep_map: bitmap of endpoints being requested by a USB configuration
+ *
+ * Ensure that a UDC is able to support the number of endpoints within a USB
+ * configuration, and that there are no resource limitations to support all
+ * requested eps.
+ *
+ * Returns zero on success, else a negative errno.
+ */
+int usb_gadget_check_config(struct usb_gadget *gadget, unsigned long ep_map)
+{
+	int ret = 0;
+
+	if (!gadget->ops->check_config)
+		goto out;
+
+	ret = gadget->ops->check_config(gadget, ep_map);
+
+out:
+	return ret;
+}
+EXPORT_SYMBOL_GPL(usb_gadget_check_config);
+
 /* ------------------------------------------------------------------------- */
 
 static void usb_gadget_state_work(struct work_struct *work)
diff --git a/include/linux/usb/gadget.h b/include/linux/usb/gadget.h
index 75c7538..fcde3b3 100644
--- a/include/linux/usb/gadget.h
+++ b/include/linux/usb/gadget.h
@@ -329,6 +329,7 @@ struct usb_gadget_ops {
 	struct usb_ep *(*match_ep)(struct usb_gadget *,
 			struct usb_endpoint_descriptor *,
 			struct usb_ss_ep_comp_descriptor *);
+	int	(*check_config)(struct usb_gadget *gadget, unsigned long ep_map);
 };
 
 /**
@@ -608,6 +609,7 @@ int usb_gadget_connect(struct usb_gadget *gadget);
 int usb_gadget_disconnect(struct usb_gadget *gadget);
 int usb_gadget_deactivate(struct usb_gadget *gadget);
 int usb_gadget_activate(struct usb_gadget *gadget);
+int usb_gadget_check_config(struct usb_gadget *gadget, unsigned long ep_map);
 #else
 static inline int usb_gadget_frame_number(struct usb_gadget *gadget)
 { return 0; }
@@ -631,6 +633,9 @@ static inline int usb_gadget_deactivate(struct usb_gadget *gadget)
 { return 0; }
 static inline int usb_gadget_activate(struct usb_gadget *gadget)
 { return 0; }
+static inline int usb_gadget_check_config(struct usb_gadget *gadget,
+					  unsigned long ep_map)
+{ return 0; }
 #endif /* CONFIG_USB_GADGET */
 
 /*-------------------------------------------------------------------------*/
-- 
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