usb: gadget: Gadget directory cleanup - group usb functions

The drivers/usb/gadget directory contains many files.
Files which are related can be distributed into separate directories.
This patch moves the USB functions implementations into a separate directory.

Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@samsung.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

1 files changed, 973 insertions, 0 deletions

diff --git a/drivers/usb/gadget/function/f_ecm.c b/drivers/usb/gadget/function/f_ecm.c
new file mode 100644
index 000000000000..798760fa7e70
--- /dev/null
+++ b/drivers/usb/gadget/function/f_ecm.c
@@ -0,0 +1,973 @@
+/*
+ * f_ecm.c -- USB CDC Ethernet (ECM) link function driver
+ *
+ * Copyright (C) 2003-2005,2008 David Brownell
+ * Copyright (C) 2008 Nokia Corporation
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+/* #define VERBOSE_DEBUG */
+
+#include <linux/slab.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/etherdevice.h>
+
+#include "u_ether.h"
+#include "u_ether_configfs.h"
+#include "u_ecm.h"
+
+
+/*
+ * This function is a "CDC Ethernet Networking Control Model" (CDC ECM)
+ * Ethernet link.  The data transfer model is simple (packets sent and
+ * received over bulk endpoints using normal short packet termination),
+ * and the control model exposes various data and optional notifications.
+ *
+ * ECM is well standardized and (except for Microsoft) supported by most
+ * operating systems with USB host support.  It's the preferred interop
+ * solution for Ethernet over USB, at least for firmware based solutions.
+ * (Hardware solutions tend to be more minimalist.)  A newer and simpler
+ * "Ethernet Emulation Model" (CDC EEM) hasn't yet caught on.
+ *
+ * Note that ECM requires the use of "alternate settings" for its data
+ * interface.  This means that the set_alt() method has real work to do,
+ * and also means that a get_alt() method is required.
+ */
+
+
+enum ecm_notify_state {
+	ECM_NOTIFY_NONE,		/* don't notify */
+	ECM_NOTIFY_CONNECT,		/* issue CONNECT next */
+	ECM_NOTIFY_SPEED,		/* issue SPEED_CHANGE next */
+};
+
+struct f_ecm {
+	struct gether			port;
+	u8				ctrl_id, data_id;
+
+	char				ethaddr[14];
+
+	struct usb_ep			*notify;
+	struct usb_request		*notify_req;
+	u8				notify_state;
+	bool				is_open;
+
+	/* FIXME is_open needs some irq-ish locking
+	 * ... possibly the same as port.ioport
+	 */
+};
+
+static inline struct f_ecm *func_to_ecm(struct usb_function *f)
+{
+	return container_of(f, struct f_ecm, port.func);
+}
+
+/* peak (theoretical) bulk transfer rate in bits-per-second */
+static inline unsigned ecm_bitrate(struct usb_gadget *g)
+{
+	if (gadget_is_superspeed(g) && g->speed == USB_SPEED_SUPER)
+		return 13 * 1024 * 8 * 1000 * 8;
+	else if (gadget_is_dualspeed(g) && g->speed == USB_SPEED_HIGH)
+		return 13 * 512 * 8 * 1000 * 8;
+	else
+		return 19 * 64 * 1 * 1000 * 8;
+}
+
+/*-------------------------------------------------------------------------*/
+
+/*
+ * Include the status endpoint if we can, even though it's optional.
+ *
+ * Use wMaxPacketSize big enough to fit CDC_NOTIFY_SPEED_CHANGE in one
+ * packet, to simplify cancellation; and a big transfer interval, to
+ * waste less bandwidth.
+ *
+ * Some drivers (like Linux 2.4 cdc-ether!) "need" it to exist even
+ * if they ignore the connect/disconnect notifications that real aether
+ * can provide.  More advanced cdc configurations might want to support
+ * encapsulated commands (vendor-specific, using control-OUT).
+ */
+
+#define ECM_STATUS_INTERVAL_MS		32
+#define ECM_STATUS_BYTECOUNT		16	/* 8 byte header + data */
+
+
+/* interface descriptor: */
+
+static struct usb_interface_assoc_descriptor
+ecm_iad_descriptor = {
+	.bLength =		sizeof ecm_iad_descriptor,
+	.bDescriptorType =	USB_DT_INTERFACE_ASSOCIATION,
+
+	/* .bFirstInterface =	DYNAMIC, */
+	.bInterfaceCount =	2,	/* control + data */
+	.bFunctionClass =	USB_CLASS_COMM,
+	.bFunctionSubClass =	USB_CDC_SUBCLASS_ETHERNET,
+	.bFunctionProtocol =	USB_CDC_PROTO_NONE,
+	/* .iFunction =		DYNAMIC */
+};
+
+
+static struct usb_interface_descriptor ecm_control_intf = {
+	.bLength =		sizeof ecm_control_intf,
+	.bDescriptorType =	USB_DT_INTERFACE,
+
+	/* .bInterfaceNumber = DYNAMIC */
+	/* status endpoint is optional; this could be patched later */
+	.bNumEndpoints =	1,
+	.bInterfaceClass =	USB_CLASS_COMM,
+	.bInterfaceSubClass =	USB_CDC_SUBCLASS_ETHERNET,
+	.bInterfaceProtocol =	USB_CDC_PROTO_NONE,
+	/* .iInterface = DYNAMIC */
+};
+
+static struct usb_cdc_header_desc ecm_header_desc = {
+	.bLength =		sizeof ecm_header_desc,
+	.bDescriptorType =	USB_DT_CS_INTERFACE,
+	.bDescriptorSubType =	USB_CDC_HEADER_TYPE,
+
+	.bcdCDC =		cpu_to_le16(0x0110),
+};
+
+static struct usb_cdc_union_desc ecm_union_desc = {
+	.bLength =		sizeof(ecm_union_desc),
+	.bDescriptorType =	USB_DT_CS_INTERFACE,
+	.bDescriptorSubType =	USB_CDC_UNION_TYPE,
+	/* .bMasterInterface0 =	DYNAMIC */
+	/* .bSlaveInterface0 =	DYNAMIC */
+};
+
+static struct usb_cdc_ether_desc ecm_desc = {
+	.bLength =		sizeof ecm_desc,
+	.bDescriptorType =	USB_DT_CS_INTERFACE,
+	.bDescriptorSubType =	USB_CDC_ETHERNET_TYPE,
+
+	/* this descriptor actually adds value, surprise! */
+	/* .iMACAddress = DYNAMIC */
+	.bmEthernetStatistics =	cpu_to_le32(0), /* no statistics */
+	.wMaxSegmentSize =	cpu_to_le16(ETH_FRAME_LEN),
+	.wNumberMCFilters =	cpu_to_le16(0),
+	.bNumberPowerFilters =	0,
+};
+
+/* the default data interface has no endpoints ... */
+
+static struct usb_interface_descriptor ecm_data_nop_intf = {
+	.bLength =		sizeof ecm_data_nop_intf,
+	.bDescriptorType =	USB_DT_INTERFACE,
+
+	.bInterfaceNumber =	1,
+	.bAlternateSetting =	0,
+	.bNumEndpoints =	0,
+	.bInterfaceClass =	USB_CLASS_CDC_DATA,
+	.bInterfaceSubClass =	0,
+	.bInterfaceProtocol =	0,
+	/* .iInterface = DYNAMIC */
+};
+
+/* ... but the "real" data interface has two bulk endpoints */
+
+static struct usb_interface_descriptor ecm_data_intf = {
+	.bLength =		sizeof ecm_data_intf,
+	.bDescriptorType =	USB_DT_INTERFACE,
+
+	.bInterfaceNumber =	1,
+	.bAlternateSetting =	1,
+	.bNumEndpoints =	2,
+	.bInterfaceClass =	USB_CLASS_CDC_DATA,
+	.bInterfaceSubClass =	0,
+	.bInterfaceProtocol =	0,
+	/* .iInterface = DYNAMIC */
+};
+
+/* full speed support: */
+
+static struct usb_endpoint_descriptor fs_ecm_notify_desc = {
+	.bLength =		USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType =	USB_DT_ENDPOINT,
+
+	.bEndpointAddress =	USB_DIR_IN,
+	.bmAttributes =		USB_ENDPOINT_XFER_INT,
+	.wMaxPacketSize =	cpu_to_le16(ECM_STATUS_BYTECOUNT),
+	.bInterval =		ECM_STATUS_INTERVAL_MS,
+};
+
+static struct usb_endpoint_descriptor fs_ecm_in_desc = {
+	.bLength =		USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType =	USB_DT_ENDPOINT,
+
+	.bEndpointAddress =	USB_DIR_IN,
+	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
+};
+
+static struct usb_endpoint_descriptor fs_ecm_out_desc = {
+	.bLength =		USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType =	USB_DT_ENDPOINT,
+
+	.bEndpointAddress =	USB_DIR_OUT,
+	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
+};
+
+static struct usb_descriptor_header *ecm_fs_function[] = {
+	/* CDC ECM control descriptors */
+	(struct usb_descriptor_header *) &ecm_iad_descriptor,
+	(struct usb_descriptor_header *) &ecm_control_intf,
+	(struct usb_descriptor_header *) &ecm_header_desc,
+	(struct usb_descriptor_header *) &ecm_union_desc,
+	(struct usb_descriptor_header *) &ecm_desc,
+
+	/* NOTE: status endpoint might need to be removed */
+	(struct usb_descriptor_header *) &fs_ecm_notify_desc,
+
+	/* data interface, altsettings 0 and 1 */
+	(struct usb_descriptor_header *) &ecm_data_nop_intf,
+	(struct usb_descriptor_header *) &ecm_data_intf,
+	(struct usb_descriptor_header *) &fs_ecm_in_desc,
+	(struct usb_descriptor_header *) &fs_ecm_out_desc,
+	NULL,
+};
+
+/* high speed support: */
+
+static struct usb_endpoint_descriptor hs_ecm_notify_desc = {
+	.bLength =		USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType =	USB_DT_ENDPOINT,
+
+	.bEndpointAddress =	USB_DIR_IN,
+	.bmAttributes =		USB_ENDPOINT_XFER_INT,
+	.wMaxPacketSize =	cpu_to_le16(ECM_STATUS_BYTECOUNT),
+	.bInterval =		USB_MS_TO_HS_INTERVAL(ECM_STATUS_INTERVAL_MS),
+};
+
+static struct usb_endpoint_descriptor hs_ecm_in_desc = {
+	.bLength =		USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType =	USB_DT_ENDPOINT,
+
+	.bEndpointAddress =	USB_DIR_IN,
+	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
+	.wMaxPacketSize =	cpu_to_le16(512),
+};
+
+static struct usb_endpoint_descriptor hs_ecm_out_desc = {
+	.bLength =		USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType =	USB_DT_ENDPOINT,
+
+	.bEndpointAddress =	USB_DIR_OUT,
+	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
+	.wMaxPacketSize =	cpu_to_le16(512),
+};
+
+static struct usb_descriptor_header *ecm_hs_function[] = {
+	/* CDC ECM control descriptors */
+	(struct usb_descriptor_header *) &ecm_iad_descriptor,
+	(struct usb_descriptor_header *) &ecm_control_intf,
+	(struct usb_descriptor_header *) &ecm_header_desc,
+	(struct usb_descriptor_header *) &ecm_union_desc,
+	(struct usb_descriptor_header *) &ecm_desc,
+
+	/* NOTE: status endpoint might need to be removed */
+	(struct usb_descriptor_header *) &hs_ecm_notify_desc,
+
+	/* data interface, altsettings 0 and 1 */
+	(struct usb_descriptor_header *) &ecm_data_nop_intf,
+	(struct usb_descriptor_header *) &ecm_data_intf,
+	(struct usb_descriptor_header *) &hs_ecm_in_desc,
+	(struct usb_descriptor_header *) &hs_ecm_out_desc,
+	NULL,
+};
+
+/* super speed support: */
+
+static struct usb_endpoint_descriptor ss_ecm_notify_desc = {
+	.bLength =		USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType =	USB_DT_ENDPOINT,
+
+	.bEndpointAddress =	USB_DIR_IN,
+	.bmAttributes =		USB_ENDPOINT_XFER_INT,
+	.wMaxPacketSize =	cpu_to_le16(ECM_STATUS_BYTECOUNT),
+	.bInterval =		USB_MS_TO_HS_INTERVAL(ECM_STATUS_INTERVAL_MS),
+};
+
+static struct usb_ss_ep_comp_descriptor ss_ecm_intr_comp_desc = {
+	.bLength =		sizeof ss_ecm_intr_comp_desc,
+	.bDescriptorType =	USB_DT_SS_ENDPOINT_COMP,
+
+	/* the following 3 values can be tweaked if necessary */
+	/* .bMaxBurst =		0, */
+	/* .bmAttributes =	0, */
+	.wBytesPerInterval =	cpu_to_le16(ECM_STATUS_BYTECOUNT),
+};
+
+static struct usb_endpoint_descriptor ss_ecm_in_desc = {
+	.bLength =		USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType =	USB_DT_ENDPOINT,
+
+	.bEndpointAddress =	USB_DIR_IN,
+	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
+	.wMaxPacketSize =	cpu_to_le16(1024),
+};
+
+static struct usb_endpoint_descriptor ss_ecm_out_desc = {
+	.bLength =		USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType =	USB_DT_ENDPOINT,
+
+	.bEndpointAddress =	USB_DIR_OUT,
+	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
+	.wMaxPacketSize =	cpu_to_le16(1024),
+};
+
+static struct usb_ss_ep_comp_descriptor ss_ecm_bulk_comp_desc = {
+	.bLength =		sizeof ss_ecm_bulk_comp_desc,
+	.bDescriptorType =	USB_DT_SS_ENDPOINT_COMP,
+
+	/* the following 2 values can be tweaked if necessary */
+	/* .bMaxBurst =		0, */
+	/* .bmAttributes =	0, */
+};
+
+static struct usb_descriptor_header *ecm_ss_function[] = {
+	/* CDC ECM control descriptors */
+	(struct usb_descriptor_header *) &ecm_iad_descriptor,
+	(struct usb_descriptor_header *) &ecm_control_intf,
+	(struct usb_descriptor_header *) &ecm_header_desc,
+	(struct usb_descriptor_header *) &ecm_union_desc,
+	(struct usb_descriptor_header *) &ecm_desc,
+
+	/* NOTE: status endpoint might need to be removed */
+	(struct usb_descriptor_header *) &ss_ecm_notify_desc,
+	(struct usb_descriptor_header *) &ss_ecm_intr_comp_desc,
+
+	/* data interface, altsettings 0 and 1 */
+	(struct usb_descriptor_header *) &ecm_data_nop_intf,
+	(struct usb_descriptor_header *) &ecm_data_intf,
+	(struct usb_descriptor_header *) &ss_ecm_in_desc,
+	(struct usb_descriptor_header *) &ss_ecm_bulk_comp_desc,
+	(struct usb_descriptor_header *) &ss_ecm_out_desc,
+	(struct usb_descriptor_header *) &ss_ecm_bulk_comp_desc,
+	NULL,
+};
+
+/* string descriptors: */
+
+static struct usb_string ecm_string_defs[] = {
+	[0].s = "CDC Ethernet Control Model (ECM)",
+	[1].s = "",
+	[2].s = "CDC Ethernet Data",
+	[3].s = "CDC ECM",
+	{  } /* end of list */
+};
+
+static struct usb_gadget_strings ecm_string_table = {
+	.language =		0x0409,	/* en-us */
+	.strings =		ecm_string_defs,
+};
+
+static struct usb_gadget_strings *ecm_strings[] = {
+	&ecm_string_table,
+	NULL,
+};
+
+/*-------------------------------------------------------------------------*/
+
+static void ecm_do_notify(struct f_ecm *ecm)
+{
+	struct usb_request		*req = ecm->notify_req;
+	struct usb_cdc_notification	*event;
+	struct usb_composite_dev	*cdev = ecm->port.func.config->cdev;
+	__le32				*data;
+	int				status;
+
+	/* notification already in flight? */
+	if (!req)
+		return;
+
+	event = req->buf;
+	switch (ecm->notify_state) {
+	case ECM_NOTIFY_NONE:
+		return;
+
+	case ECM_NOTIFY_CONNECT:
+		event->bNotificationType = USB_CDC_NOTIFY_NETWORK_CONNECTION;
+		if (ecm->is_open)
+			event->wValue = cpu_to_le16(1);
+		else
+			event->wValue = cpu_to_le16(0);
+		event->wLength = 0;
+		req->length = sizeof *event;
+
+		DBG(cdev, "notify connect %s\n",
+				ecm->is_open ? "true" : "false");
+		ecm->notify_state = ECM_NOTIFY_SPEED;
+		break;
+
+	case ECM_NOTIFY_SPEED:
+		event->bNotificationType = USB_CDC_NOTIFY_SPEED_CHANGE;
+		event->wValue = cpu_to_le16(0);
+		event->wLength = cpu_to_le16(8);
+		req->length = ECM_STATUS_BYTECOUNT;
+
+		/* SPEED_CHANGE data is up/down speeds in bits/sec */
+		data = req->buf + sizeof *event;
+		data[0] = cpu_to_le32(ecm_bitrate(cdev->gadget));
+		data[1] = data[0];
+
+		DBG(cdev, "notify speed %d\n", ecm_bitrate(cdev->gadget));
+		ecm->notify_state = ECM_NOTIFY_NONE;
+		break;
+	}
+	event->bmRequestType = 0xA1;
+	event->wIndex = cpu_to_le16(ecm->ctrl_id);
+
+	ecm->notify_req = NULL;
+	status = usb_ep_queue(ecm->notify, req, GFP_ATOMIC);
+	if (status < 0) {
+		ecm->notify_req = req;
+		DBG(cdev, "notify --> %d\n", status);
+	}
+}
+
+static void ecm_notify(struct f_ecm *ecm)
+{
+	/* NOTE on most versions of Linux, host side cdc-ethernet
+	 * won't listen for notifications until its netdevice opens.
+	 * The first notification then sits in the FIFO for a long
+	 * time, and the second one is queued.
+	 */
+	ecm->notify_state = ECM_NOTIFY_CONNECT;
+	ecm_do_notify(ecm);
+}
+
+static void ecm_notify_complete(struct usb_ep *ep, struct usb_request *req)
+{
+	struct f_ecm			*ecm = req->context;
+	struct usb_composite_dev	*cdev = ecm->port.func.config->cdev;
+	struct usb_cdc_notification	*event = req->buf;
+
+	switch (req->status) {
+	case 0:
+		/* no fault */
+		break;
+	case -ECONNRESET:
+	case -ESHUTDOWN:
+		ecm->notify_state = ECM_NOTIFY_NONE;
+		break;
+	default:
+		DBG(cdev, "event %02x --> %d\n",
+			event->bNotificationType, req->status);
+		break;
+	}
+	ecm->notify_req = req;
+	ecm_do_notify(ecm);
+}
+
+static int ecm_setup(struct usb_function *f, const struct usb_ctrlrequest *ctrl)
+{
+	struct f_ecm		*ecm = func_to_ecm(f);
+	struct usb_composite_dev *cdev = f->config->cdev;
+	struct usb_request	*req = cdev->req;
+	int			value = -EOPNOTSUPP;
+	u16			w_index = le16_to_cpu(ctrl->wIndex);
+	u16			w_value = le16_to_cpu(ctrl->wValue);
+	u16			w_length = le16_to_cpu(ctrl->wLength);
+
+	/* composite driver infrastructure handles everything except
+	 * CDC class messages; interface activation uses set_alt().
+	 */
+	switch ((ctrl->bRequestType << 8) | ctrl->bRequest) {
+	case ((USB_DIR_OUT | USB_TYPE_CLASS | USB_RECIP_INTERFACE) << 8)
+			| USB_CDC_SET_ETHERNET_PACKET_FILTER:
+		/* see 6.2.30: no data, wIndex = interface,
+		 * wValue = packet filter bitmap
+		 */
+		if (w_length != 0 || w_index != ecm->ctrl_id)
+			goto invalid;
+		DBG(cdev, "packet filter %02x\n", w_value);
+		/* REVISIT locking of cdc_filter.  This assumes the UDC
+		 * driver won't have a concurrent packet TX irq running on
+		 * another CPU; or that if it does, this write is atomic...
+		 */
+		ecm->port.cdc_filter = w_value;
+		value = 0;
+		break;
+
+	/* and optionally:
+	 * case USB_CDC_SEND_ENCAPSULATED_COMMAND:
+	 * case USB_CDC_GET_ENCAPSULATED_RESPONSE:
+	 * case USB_CDC_SET_ETHERNET_MULTICAST_FILTERS:
+	 * case USB_CDC_SET_ETHERNET_PM_PATTERN_FILTER:
+	 * case USB_CDC_GET_ETHERNET_PM_PATTERN_FILTER:
+	 * case USB_CDC_GET_ETHERNET_STATISTIC:
+	 */
+
+	default:
+invalid:
+		DBG(cdev, "invalid control req%02x.%02x v%04x i%04x l%d\n",
+			ctrl->bRequestType, ctrl->bRequest,
+			w_value, w_index, w_length);
+	}
+
+	/* respond with data transfer or status phase? */
+	if (value >= 0) {
+		DBG(cdev, "ecm req%02x.%02x v%04x i%04x l%d\n",
+			ctrl->bRequestType, ctrl->bRequest,
+			w_value, w_index, w_length);
+		req->zero = 0;
+		req->length = value;
+		value = usb_ep_queue(cdev->gadget->ep0, req, GFP_ATOMIC);
+		if (value < 0)
+			ERROR(cdev, "ecm req %02x.%02x response err %d\n",
+					ctrl->bRequestType, ctrl->bRequest,
+					value);
+	}
+
+	/* device either stalls (value < 0) or reports success */
+	return value;
+}
+
+
+static int ecm_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
+{
+	struct f_ecm		*ecm = func_to_ecm(f);
+	struct usb_composite_dev *cdev = f->config->cdev;
+
+	/* Control interface has only altsetting 0 */
+	if (intf == ecm->ctrl_id) {
+		if (alt != 0)
+			goto fail;
+
+		if (ecm->notify->driver_data) {
+			VDBG(cdev, "reset ecm control %d\n", intf);
+			usb_ep_disable(ecm->notify);
+		}
+		if (!(ecm->notify->desc)) {
+			VDBG(cdev, "init ecm ctrl %d\n", intf);
+			if (config_ep_by_speed(cdev->gadget, f, ecm->notify))
+				goto fail;
+		}
+		usb_ep_enable(ecm->notify);
+		ecm->notify->driver_data = ecm;
+
+	/* Data interface has two altsettings, 0 and 1 */
+	} else if (intf == ecm->data_id) {
+		if (alt > 1)
+			goto fail;
+
+		if (ecm->port.in_ep->driver_data) {
+			DBG(cdev, "reset ecm\n");
+			gether_disconnect(&ecm->port);
+		}
+
+		if (!ecm->port.in_ep->desc ||
+		    !ecm->port.out_ep->desc) {
+			DBG(cdev, "init ecm\n");
+			if (config_ep_by_speed(cdev->gadget, f,
+					       ecm->port.in_ep) ||
+			    config_ep_by_speed(cdev->gadget, f,
+					       ecm->port.out_ep)) {
+				ecm->port.in_ep->desc = NULL;
+				ecm->port.out_ep->desc = NULL;
+				goto fail;
+			}
+		}
+
+		/* CDC Ethernet only sends data in non-default altsettings.
+		 * Changing altsettings resets filters, statistics, etc.
+		 */
+		if (alt == 1) {
+			struct net_device	*net;
+
+			/* Enable zlps by default for ECM conformance;
+			 * override for musb_hdrc (avoids txdma ovhead).
+			 */
+			ecm->port.is_zlp_ok = !(gadget_is_musbhdrc(cdev->gadget)
+				);
+			ecm->port.cdc_filter = DEFAULT_FILTER;
+			DBG(cdev, "activate ecm\n");
+			net = gether_connect(&ecm->port);
+			if (IS_ERR(net))
+				return PTR_ERR(net);
+		}
+
+		/* NOTE this can be a minor disagreement with the ECM spec,
+		 * which says speed notifications will "always" follow
+		 * connection notifications.  But we allow one connect to
+		 * follow another (if the first is in flight), and instead
+		 * just guarantee that a speed notification is always sent.
+		 */
+		ecm_notify(ecm);
+	} else
+		goto fail;
+
+	return 0;
+fail:
+	return -EINVAL;
+}
+
+/* Because the data interface supports multiple altsettings,
+ * this ECM function *MUST* implement a get_alt() method.
+ */
+static int ecm_get_alt(struct usb_function *f, unsigned intf)
+{
+	struct f_ecm		*ecm = func_to_ecm(f);
+
+	if (intf == ecm->ctrl_id)
+		return 0;
+	return ecm->port.in_ep->driver_data ? 1 : 0;
+}
+
+static void ecm_disable(struct usb_function *f)
+{
+	struct f_ecm		*ecm = func_to_ecm(f);
+	struct usb_composite_dev *cdev = f->config->cdev;
+
+	DBG(cdev, "ecm deactivated\n");
+
+	if (ecm->port.in_ep->driver_data)
+		gether_disconnect(&ecm->port);
+
+	if (ecm->notify->driver_data) {
+		usb_ep_disable(ecm->notify);
+		ecm->notify->driver_data = NULL;
+		ecm->notify->desc = NULL;
+	}
+}
+
+/*-------------------------------------------------------------------------*/
+
+/*
+ * Callbacks let us notify the host about connect/disconnect when the
+ * net device is opened or closed.
+ *
+ * For testing, note that link states on this side include both opened
+ * and closed variants of:
+ *
+ *   - disconnected/unconfigured
+ *   - configured but inactive (data alt 0)
+ *   - configured and active (data alt 1)
+ *
+ * Each needs to be tested with unplug, rmmod, SET_CONFIGURATION, and
+ * SET_INTERFACE (altsetting).  Remember also that "configured" doesn't
+ * imply the host is actually polling the notification endpoint, and
+ * likewise that "active" doesn't imply it's actually using the data
+ * endpoints for traffic.
+ */
+
+static void ecm_open(struct gether *geth)
+{
+	struct f_ecm		*ecm = func_to_ecm(&geth->func);
+
+	DBG(ecm->port.func.config->cdev, "%s\n", __func__);
+
+	ecm->is_open = true;
+	ecm_notify(ecm);
+}
+
+static void ecm_close(struct gether *geth)
+{
+	struct f_ecm		*ecm = func_to_ecm(&geth->func);
+
+	DBG(ecm->port.func.config->cdev, "%s\n", __func__);
+
+	ecm->is_open = false;
+	ecm_notify(ecm);
+}
+
+/*-------------------------------------------------------------------------*/
+
+/* ethernet function driver setup/binding */
+
+static int
+ecm_bind(struct usb_configuration *c, struct usb_function *f)
+{
+	struct usb_composite_dev *cdev = c->cdev;
+	struct f_ecm		*ecm = func_to_ecm(f);
+	struct usb_string	*us;
+	int			status;
+	struct usb_ep		*ep;
+
+	struct f_ecm_opts	*ecm_opts;
+
+	if (!can_support_ecm(cdev->gadget))
+		return -EINVAL;
+
+	ecm_opts = container_of(f->fi, struct f_ecm_opts, func_inst);
+
+	/*
+	 * in drivers/usb/gadget/configfs.c:configfs_composite_bind()
+	 * configurations are bound in sequence with list_for_each_entry,
+	 * in each configuration its functions are bound in sequence
+	 * with list_for_each_entry, so we assume no race condition
+	 * with regard to ecm_opts->bound access
+	 */
+	if (!ecm_opts->bound) {
+		mutex_lock(&ecm_opts->lock);
+		gether_set_gadget(ecm_opts->net, cdev->gadget);
+		status = gether_register_netdev(ecm_opts->net);
+		mutex_unlock(&ecm_opts->lock);
+		if (status)
+			return status;
+		ecm_opts->bound = true;
+	}
+
+	us = usb_gstrings_attach(cdev, ecm_strings,
+				 ARRAY_SIZE(ecm_string_defs));
+	if (IS_ERR(us))
+		return PTR_ERR(us);
+	ecm_control_intf.iInterface = us[0].id;
+	ecm_data_intf.iInterface = us[2].id;
+	ecm_desc.iMACAddress = us[1].id;
+	ecm_iad_descriptor.iFunction = us[3].id;
+
+	/* allocate instance-specific interface IDs */
+	status = usb_interface_id(c, f);
+	if (status < 0)
+		goto fail;
+	ecm->ctrl_id = status;
+	ecm_iad_descriptor.bFirstInterface = status;
+
+	ecm_control_intf.bInterfaceNumber = status;
+	ecm_union_desc.bMasterInterface0 = status;
+
+	status = usb_interface_id(c, f);
+	if (status < 0)
+		goto fail;
+	ecm->data_id = status;
+
+	ecm_data_nop_intf.bInterfaceNumber = status;
+	ecm_data_intf.bInterfaceNumber = status;
+	ecm_union_desc.bSlaveInterface0 = status;
+
+	status = -ENODEV;
+
+	/* allocate instance-specific endpoints */
+	ep = usb_ep_autoconfig(cdev->gadget, &fs_ecm_in_desc);
+	if (!ep)
+		goto fail;
+	ecm->port.in_ep = ep;
+	ep->driver_data = cdev;	/* claim */
+
+	ep = usb_ep_autoconfig(cdev->gadget, &fs_ecm_out_desc);
+	if (!ep)
+		goto fail;
+	ecm->port.out_ep = ep;
+	ep->driver_data = cdev;	/* claim */
+
+	/* NOTE:  a status/notification endpoint is *OPTIONAL* but we
+	 * don't treat it that way.  It's simpler, and some newer CDC
+	 * profiles (wireless handsets) no longer treat it as optional.
+	 */
+	ep = usb_ep_autoconfig(cdev->gadget, &fs_ecm_notify_desc);
+	if (!ep)
+		goto fail;
+	ecm->notify = ep;
+	ep->driver_data = cdev;	/* claim */
+
+	status = -ENOMEM;
+
+	/* allocate notification request and buffer */
+	ecm->notify_req = usb_ep_alloc_request(ep, GFP_KERNEL);
+	if (!ecm->notify_req)
+		goto fail;
+	ecm->notify_req->buf = kmalloc(ECM_STATUS_BYTECOUNT, GFP_KERNEL);
+	if (!ecm->notify_req->buf)
+		goto fail;
+	ecm->notify_req->context = ecm;
+	ecm->notify_req->complete = ecm_notify_complete;
+
+	/* support all relevant hardware speeds... we expect that when
+	 * hardware is dual speed, all bulk-capable endpoints work at
+	 * both speeds
+	 */
+	hs_ecm_in_desc.bEndpointAddress = fs_ecm_in_desc.bEndpointAddress;
+	hs_ecm_out_desc.bEndpointAddress = fs_ecm_out_desc.bEndpointAddress;
+	hs_ecm_notify_desc.bEndpointAddress =
+		fs_ecm_notify_desc.bEndpointAddress;
+
+	ss_ecm_in_desc.bEndpointAddress = fs_ecm_in_desc.bEndpointAddress;
+	ss_ecm_out_desc.bEndpointAddress = fs_ecm_out_desc.bEndpointAddress;
+	ss_ecm_notify_desc.bEndpointAddress =
+		fs_ecm_notify_desc.bEndpointAddress;
+
+	status = usb_assign_descriptors(f, ecm_fs_function, ecm_hs_function,
+			ecm_ss_function);
+	if (status)
+		goto fail;
+
+	/* NOTE:  all that is done without knowing or caring about
+	 * the network link ... which is unavailable to this code
+	 * until we're activated via set_alt().
+	 */
+
+	ecm->port.open = ecm_open;
+	ecm->port.close = ecm_close;
+
+	DBG(cdev, "CDC Ethernet: %s speed IN/%s OUT/%s NOTIFY/%s\n",
+			gadget_is_superspeed(c->cdev->gadget) ? "super" :
+			gadget_is_dualspeed(c->cdev->gadget) ? "dual" : "full",
+			ecm->port.in_ep->name, ecm->port.out_ep->name,
+			ecm->notify->name);
+	return 0;
+
+fail:
+	if (ecm->notify_req) {
+		kfree(ecm->notify_req->buf);
+		usb_ep_free_request(ecm->notify, ecm->notify_req);
+	}
+
+	/* we might as well release our claims on endpoints */
+	if (ecm->notify)
+		ecm->notify->driver_data = NULL;
+	if (ecm->port.out_ep)
+		ecm->port.out_ep->driver_data = NULL;
+	if (ecm->port.in_ep)
+		ecm->port.in_ep->driver_data = NULL;
+
+	ERROR(cdev, "%s: can't bind, err %d\n", f->name, status);
+
+	return status;
+}
+
+static inline struct f_ecm_opts *to_f_ecm_opts(struct config_item *item)
+{
+	return container_of(to_config_group(item), struct f_ecm_opts,
+			    func_inst.group);
+}
+
+/* f_ecm_item_ops */
+USB_ETHERNET_CONFIGFS_ITEM(ecm);
+
+/* f_ecm_opts_dev_addr */
+USB_ETHERNET_CONFIGFS_ITEM_ATTR_DEV_ADDR(ecm);
+
+/* f_ecm_opts_host_addr */
+USB_ETHERNET_CONFIGFS_ITEM_ATTR_HOST_ADDR(ecm);
+
+/* f_ecm_opts_qmult */
+USB_ETHERNET_CONFIGFS_ITEM_ATTR_QMULT(ecm);
+
+/* f_ecm_opts_ifname */
+USB_ETHERNET_CONFIGFS_ITEM_ATTR_IFNAME(ecm);
+
+static struct configfs_attribute *ecm_attrs[] = {
+	&f_ecm_opts_dev_addr.attr,
+	&f_ecm_opts_host_addr.attr,
+	&f_ecm_opts_qmult.attr,
+	&f_ecm_opts_ifname.attr,
+	NULL,
+};
+
+static struct config_item_type ecm_func_type = {
+	.ct_item_ops	= &ecm_item_ops,
+	.ct_attrs	= ecm_attrs,
+	.ct_owner	= THIS_MODULE,
+};
+
+static void ecm_free_inst(struct usb_function_instance *f)
+{
+	struct f_ecm_opts *opts;
+
+	opts = container_of(f, struct f_ecm_opts, func_inst);
+	if (opts->bound)
+		gether_cleanup(netdev_priv(opts->net));
+	else
+		free_netdev(opts->net);
+	kfree(opts);
+}
+
+static struct usb_function_instance *ecm_alloc_inst(void)
+{
+	struct f_ecm_opts *opts;
+
+	opts = kzalloc(sizeof(*opts), GFP_KERNEL);
+	if (!opts)
+		return ERR_PTR(-ENOMEM);
+	mutex_init(&opts->lock);
+	opts->func_inst.free_func_inst = ecm_free_inst;
+	opts->net = gether_setup_default();
+	if (IS_ERR(opts->net)) {
+		struct net_device *net = opts->net;
+		kfree(opts);
+		return ERR_CAST(net);
+	}
+
+	config_group_init_type_name(&opts->func_inst.group, "", &ecm_func_type);
+
+	return &opts->func_inst;
+}
+
+static void ecm_free(struct usb_function *f)
+{
+	struct f_ecm *ecm;
+	struct f_ecm_opts *opts;
+
+	ecm = func_to_ecm(f);
+	opts = container_of(f->fi, struct f_ecm_opts, func_inst);
+	kfree(ecm);
+	mutex_lock(&opts->lock);
+	opts->refcnt--;
+	mutex_unlock(&opts->lock);
+}
+
+static void ecm_unbind(struct usb_configuration *c, struct usb_function *f)
+{
+	struct f_ecm		*ecm = func_to_ecm(f);
+
+	DBG(c->cdev, "ecm unbind\n");
+
+	usb_free_all_descriptors(f);
+
+	kfree(ecm->notify_req->buf);
+	usb_ep_free_request(ecm->notify, ecm->notify_req);
+}
+
+static struct usb_function *ecm_alloc(struct usb_function_instance *fi)
+{
+	struct f_ecm	*ecm;
+	struct f_ecm_opts *opts;
+	int status;
+
+	/* allocate and initialize one new instance */
+	ecm = kzalloc(sizeof(*ecm), GFP_KERNEL);
+	if (!ecm)
+		return ERR_PTR(-ENOMEM);
+
+	opts = container_of(fi, struct f_ecm_opts, func_inst);
+	mutex_lock(&opts->lock);
+	opts->refcnt++;
+
+	/* export host's Ethernet address in CDC format */
+	status = gether_get_host_addr_cdc(opts->net, ecm->ethaddr,
+					  sizeof(ecm->ethaddr));
+	if (status < 12) {
+		kfree(ecm);
+		mutex_unlock(&opts->lock);
+		return ERR_PTR(-EINVAL);
+	}
+	ecm_string_defs[1].s = ecm->ethaddr;
+
+	ecm->port.ioport = netdev_priv(opts->net);
+	mutex_unlock(&opts->lock);
+	ecm->port.cdc_filter = DEFAULT_FILTER;
+
+	ecm->port.func.name = "cdc_ethernet";
+	/* descriptors are per-instance copies */
+	ecm->port.func.bind = ecm_bind;
+	ecm->port.func.unbind = ecm_unbind;
+	ecm->port.func.set_alt = ecm_set_alt;
+	ecm->port.func.get_alt = ecm_get_alt;
+	ecm->port.func.setup = ecm_setup;
+	ecm->port.func.disable = ecm_disable;
+	ecm->port.func.free_func = ecm_free;
+
+	return &ecm->port.func;
+}
+
+DECLARE_USB_FUNCTION_INIT(ecm, ecm_alloc_inst, ecm_alloc);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("David Brownell");