usb ethernet gadget: split CDC Subset function

This is a simple "CDC Subset" (and MCCI "SAFE") function driver, extracted
from the all-in-one Ethernet gadget driver.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/gadget/Makefile

@@ -25,7 +25,7 @@ obj-$(CONFIG_USB_M66592)	+= m66592-udc.o
 C_UTILS =	composite.o usbstring.o config.o epautoconf.o
 
 g_zero-objs			:= zero.o f_sourcesink.o f_loopback.o $(C_UTILS)
-g_ether-objs			:= ether.o u_ether.o $(C_UTILS)
+g_ether-objs			:= ether.o u_ether.o f_subset.o $(C_UTILS)
 g_serial-objs			:= serial.o u_serial.o f_acm.o f_serial.o $(C_UTILS)
 g_midi-objs			:= gmidi.o usbstring.o config.o epautoconf.o
 gadgetfs-objs			:= inode.o

drivers/usb/gadget/f_subset.c

+/*
+ * f_subset.c -- "CDC Subset" Ethernet 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.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#include <linux/kernel.h>
+#include <linux/device.h>
+#include <linux/etherdevice.h>
+
+#include "u_ether.h"
+
+
+/*
+ * This function packages a simple "CDC Subset" Ethernet port with no real
+ * control mechanisms; just raw data transfer over two bulk endpoints.
+ * The data transfer model is exactly that of CDC Ethernet, which is
+ * why we call it the "CDC Subset".
+ *
+ * Because it's not standardized, this has some interoperability issues.
+ * They mostly relate to driver binding, since the data transfer model is
+ * so simple (CDC Ethernet).  The original versions of this protocol used
+ * specific product/vendor IDs:  byteswapped IDs for Digital Equipment's
+ * SA-1100 "Itsy" board, which could run Linux 2.4 kernels and supported
+ * daughtercards with USB peripheral connectors.  (It was used more often
+ * with other boards, using the Itsy identifiers.)  Linux hosts recognized
+ * this with CONFIG_USB_ARMLINUX; these devices have only one configuration
+ * and one interface.
+ *
+ * At some point, MCCI defined a (nonconformant) CDC MDLM variant called
+ * "SAFE", which happens to have a mode which is identical to the "CDC
+ * Subset" in terms of data transfer and lack of control model.  This was
+ * adopted by later Sharp Zaurus models, and by some other software which
+ * Linux hosts recognize with CONFIG_USB_NET_ZAURUS.
+ *
+ * Because Microsoft's RNDIS drivers are far from robust, we added a few
+ * descriptors to the CDC Subset code, making this code look like a SAFE
+ * implementation.  This lets you use MCCI's host side MS-Windows drivers
+ * if you get fed up with RNDIS.  It also makes it easier for composite
+ * drivers to work, since they can use class based binding instead of
+ * caring about specific product and vendor IDs.
+ */
+
+struct geth_descs {
+	struct usb_endpoint_descriptor	*in;
+	struct usb_endpoint_descriptor	*out;
+};
+
+struct f_gether {
+	struct gether			port;
+
+	char				ethaddr[14];
+
+	struct usb_descriptor_header	**fs_function;
+	struct geth_descs		fs;
+	struct usb_descriptor_header	**hs_function;
+	struct geth_descs		hs;
+};
+
+static inline struct f_gether *func_to_geth(struct usb_function *f)
+{
+	return container_of(f, struct f_gether, port.func);
+}
+
+/*-------------------------------------------------------------------------*/
+
+/*
+ * "Simple" CDC-subset option is a simple vendor-neutral model that most
+ * full speed controllers can handle:  one interface, two bulk endpoints.
+ * To assist host side drivers, we fancy it up a bit, and add descriptors so
+ * some host side drivers will understand it as a "SAFE" variant.
+ *
+ * "SAFE" loosely follows CDC WMC MDLM, violating the spec in various ways.
+ * Data endpoints live in the control interface, there's no data interface.
+ * And it's not used to talk to a cell phone radio.
+ */
+
+/* interface descriptor: */
+
+static struct usb_interface_descriptor subset_data_intf __initdata = {
+	.bLength =		sizeof subset_data_intf,
+	.bDescriptorType =	USB_DT_INTERFACE,
+
+	/* .bInterfaceNumber = DYNAMIC */
+	.bAlternateSetting =	0,
+	.bNumEndpoints =	2,
+	.bInterfaceClass =      USB_CLASS_COMM,
+	.bInterfaceSubClass =	USB_CDC_SUBCLASS_MDLM,
+	.bInterfaceProtocol =	0,
+	/* .iInterface = DYNAMIC */
+};
+
+static struct usb_cdc_header_desc header_desc __initdata = {
+	.bLength =		sizeof header_desc,
+	.bDescriptorType =	USB_DT_CS_INTERFACE,
+	.bDescriptorSubType =	USB_CDC_HEADER_TYPE,
+
+	.bcdCDC =		__constant_cpu_to_le16(0x0110),
+};
+
+static struct usb_cdc_mdlm_desc mdlm_desc __initdata = {
+	.bLength =		sizeof mdlm_desc,
+	.bDescriptorType =	USB_DT_CS_INTERFACE,
+	.bDescriptorSubType =	USB_CDC_MDLM_TYPE,
+
+	.bcdVersion =		__constant_cpu_to_le16(0x0100),
+	.bGUID = {
+		0x5d, 0x34, 0xcf, 0x66, 0x11, 0x18, 0x11, 0xd6,
+		0xa2, 0x1a, 0x00, 0x01, 0x02, 0xca, 0x9a, 0x7f,
+	},
+};
+
+/* since "usb_cdc_mdlm_detail_desc" is a variable length structure, we
+ * can't really use its struct.  All we do here is say that we're using
+ * the submode of "SAFE" which directly matches the CDC Subset.
+ */
+static u8 mdlm_detail_desc[] __initdata = {
+	6,
+	USB_DT_CS_INTERFACE,
+	USB_CDC_MDLM_DETAIL_TYPE,
+
+	0,	/* "SAFE" */
+	0,	/* network control capabilities (none) */
+	0,	/* network data capabilities ("raw" encapsulation) */
+};
+
+static struct usb_cdc_ether_desc ether_desc __initdata = {
+	.bLength =		sizeof ether_desc,
+	.bDescriptorType =	USB_DT_CS_INTERFACE,
+	.bDescriptorSubType =	USB_CDC_ETHERNET_TYPE,
+
+	/* this descriptor actually adds value, surprise! */
+	/* .iMACAddress = DYNAMIC */
+	.bmEthernetStatistics =	__constant_cpu_to_le32(0), /* no statistics */
+	.wMaxSegmentSize =	__constant_cpu_to_le16(ETH_FRAME_LEN),
+	.wNumberMCFilters =	__constant_cpu_to_le16(0),
+	.bNumberPowerFilters =	0,
+};
+
+/* full speed support: */
+
+static struct usb_endpoint_descriptor fs_in_desc __initdata = {
+	.bLength =		USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType =	USB_DT_ENDPOINT,
+
+	.bEndpointAddress =	USB_DIR_IN,
+	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
+};
+
+static struct usb_endpoint_descriptor fs_out_desc __initdata = {
+	.bLength =		USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType =	USB_DT_ENDPOINT,
+
+	.bEndpointAddress =	USB_DIR_OUT,
+	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
+};
+
+static struct usb_descriptor_header *fs_eth_function[] __initdata = {
+	(struct usb_descriptor_header *) &subset_data_intf,
+	(struct usb_descriptor_header *) &header_desc,
+	(struct usb_descriptor_header *) &mdlm_desc,
+	(struct usb_descriptor_header *) &mdlm_detail_desc,
+	(struct usb_descriptor_header *) &ether_desc,
+	(struct usb_descriptor_header *) &fs_in_desc,
+	(struct usb_descriptor_header *) &fs_out_desc,
+	NULL,
+};
+
+/* high speed support: */
+
+static struct usb_endpoint_descriptor hs_in_desc __initdata = {
+	.bLength =		USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType =	USB_DT_ENDPOINT,
+
+	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
+	.wMaxPacketSize =	__constant_cpu_to_le16(512),
+};
+
+static struct usb_endpoint_descriptor hs_out_desc __initdata = {
+	.bLength =		USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType =	USB_DT_ENDPOINT,
+
+	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
+	.wMaxPacketSize =	__constant_cpu_to_le16(512),
+};
+
+static struct usb_descriptor_header *hs_eth_function[] __initdata = {
+	(struct usb_descriptor_header *) &subset_data_intf,
+	(struct usb_descriptor_header *) &header_desc,
+	(struct usb_descriptor_header *) &mdlm_desc,
+	(struct usb_descriptor_header *) &mdlm_detail_desc,
+	(struct usb_descriptor_header *) &ether_desc,
+	(struct usb_descriptor_header *) &hs_in_desc,
+	(struct usb_descriptor_header *) &hs_out_desc,
+	NULL,
+};
+
+/* string descriptors: */
+
+static struct usb_string geth_string_defs[] = {
+	[0].s = "CDC Ethernet Subset/SAFE",
+	[1].s = NULL /* DYNAMIC */,
+	{  } /* end of list */
+};
+
+static struct usb_gadget_strings geth_string_table = {
+	.language =		0x0409,	/* en-us */
+	.strings =		geth_string_defs,
+};
+
+static struct usb_gadget_strings *geth_strings[] = {
+	&geth_string_table,
+	NULL,
+};
+
+/*-------------------------------------------------------------------------*/
+
+static int geth_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
+{
+	struct f_gether		*geth = func_to_geth(f);
+	struct usb_composite_dev *cdev = f->config->cdev;
+	struct net_device	*net;
+
+	/* we know alt == 0, so this is an activation or a reset */
+
+	if (geth->port.in_ep->driver_data) {
+		DBG(cdev, "reset cdc subset\n");
+		gether_disconnect(&geth->port);
+	}
+
+	DBG(cdev, "init + activate cdc subset\n");
+	geth->port.in = ep_choose(cdev->gadget,
+			geth->hs.in, geth->fs.in);
+	geth->port.out = ep_choose(cdev->gadget,
+			geth->hs.out, geth->fs.out);
+
+	net = gether_connect(&geth->port);
+	return IS_ERR(net) ? PTR_ERR(net) : 0;
+}
+
+static void geth_disable(struct usb_function *f)
+{
+	struct f_gether	*geth = func_to_geth(f);
+	struct usb_composite_dev *cdev = f->config->cdev;
+
+	DBG(cdev, "net deactivated\n");
+	gether_disconnect(&geth->port);
+}
+
+/*-------------------------------------------------------------------------*/
+
+/* serial function driver setup/binding */
+
+static int __init
+geth_bind(struct usb_configuration *c, struct usb_function *f)
+{
+	struct usb_composite_dev *cdev = c->cdev;
+	struct f_gether		*geth = func_to_geth(f);
+	int			status;
+	struct usb_ep		*ep;
+
+	/* allocate instance-specific interface IDs */
+	status = usb_interface_id(c, f);
+	if (status < 0)
+		goto fail;
+	subset_data_intf.bInterfaceNumber = status;
+
+	status = -ENODEV;
+
+	/* allocate instance-specific endpoints */
+	ep = usb_ep_autoconfig(cdev->gadget, &fs_in_desc);
+	if (!ep)
+		goto fail;
+	geth->port.in_ep = ep;
+	ep->driver_data = cdev;	/* claim */
+
+	ep = usb_ep_autoconfig(cdev->gadget, &fs_out_desc);
+	if (!ep)
+		goto fail;
+	geth->port.out_ep = ep;
+	ep->driver_data = cdev;	/* claim */
+
+	/* copy descriptors, and track endpoint copies */
+	f->descriptors = usb_copy_descriptors(fs_eth_function);
+
+	geth->fs.in = usb_find_endpoint(fs_eth_function,
+			f->descriptors, &fs_in_desc);
+	geth->fs.out = usb_find_endpoint(fs_eth_function,
+			f->descriptors, &fs_out_desc);
+
+
+	/* support all relevant hardware speeds... we expect that when
+	 * hardware is dual speed, all bulk-capable endpoints work at
+	 * both speeds
+	 */
+	if (gadget_is_dualspeed(c->cdev->gadget)) {
+		hs_in_desc.bEndpointAddress =
+				fs_in_desc.bEndpointAddress;
+		hs_out_desc.bEndpointAddress =
+				fs_out_desc.bEndpointAddress;
+
+		/* copy descriptors, and track endpoint copies */
+		f->hs_descriptors = usb_copy_descriptors(hs_eth_function);
+
+		geth->hs.in = usb_find_endpoint(hs_eth_function,
+				f->hs_descriptors, &hs_in_desc);
+		geth->hs.out = usb_find_endpoint(hs_eth_function,
+				f->hs_descriptors, &hs_out_desc);
+	}
+
+	/* 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().
+	 */
+
+	DBG(cdev, "CDC Subset: %s speed IN/%s OUT/%s\n",
+			gadget_is_dualspeed(c->cdev->gadget) ? "dual" : "full",
+			geth->port.in_ep->name, geth->port.out_ep->name);
+	return 0;
+
+fail:
+	/* we might as well release our claims on endpoints */
+	if (geth->port.out)
+		geth->port.out_ep->driver_data = NULL;
+	if (geth->port.in)
+		geth->port.in_ep->driver_data = NULL;
+
+	ERROR(cdev, "%s: can't bind, err %d\n", f->name, status);
+
+	return status;
+}
+
+static void
+geth_unbind(struct usb_configuration *c, struct usb_function *f)
+{
+	if (gadget_is_dualspeed(c->cdev->gadget))
+		usb_free_descriptors(f->hs_descriptors);
+	usb_free_descriptors(f->descriptors);
+	geth_string_defs[1].s = NULL;
+	kfree(func_to_geth(f));
+}
+
+/**
+ * geth_bind_config - add CDC Subset network link to a configuration
+ * @c: the configuration to support the network link
+ * @ethaddr: a buffer in which the ethernet address of the host side
+ *	side of the link was recorded
+ * Context: single threaded during gadget setup
+ *
+ * Returns zero on success, else negative errno.
+ *
+ * Caller must have called @gether_setup().  Caller is also responsible
+ * for calling @gether_cleanup() before module unload.
+ */
+int __init geth_bind_config(struct usb_configuration *c, u8 ethaddr[ETH_ALEN])
+{
+	struct f_gether	*geth;
+	int		status;
+
+	if (!ethaddr)
+		return -EINVAL;
+
+	/* maybe allocate device-global string IDs */
+	if (geth_string_defs[0].id == 0) {
+
+		/* interface label */
+		status = usb_string_id(c->cdev);
+		if (status < 0)
+			return status;
+		geth_string_defs[0].id = status;
+		subset_data_intf.iInterface = status;
+
+		/* MAC address */
+		status = usb_string_id(c->cdev);
+		if (status < 0)
+			return status;
+		geth_string_defs[1].id = status;
+		ether_desc.iMACAddress = status;
+	}
+
+	/* allocate and initialize one new instance */
+	geth = kzalloc(sizeof *geth, GFP_KERNEL);
+	if (!geth)
+		return -ENOMEM;
+
+	/* export host's Ethernet address in CDC format */
+	snprintf(geth->ethaddr, sizeof geth->ethaddr,
+		"%02X%02X%02X%02X%02X%02X",
+		ethaddr[0], ethaddr[1], ethaddr[2],
+		ethaddr[3], ethaddr[4], ethaddr[5]);
+	geth_string_defs[1].s = geth->ethaddr;
+
+	geth->port.cdc_filter = DEFAULT_FILTER;
+
+	geth->port.func.name = "cdc_subset";
+	geth->port.func.strings = geth_strings;
+	geth->port.func.bind = geth_bind;
+	geth->port.func.unbind = geth_unbind;
+	geth->port.func.set_alt = geth_set_alt;
+	geth->port.func.disable = geth_disable;
+
+	status = usb_add_function(c, &geth->port.func);
+	if (status) {
+		geth_string_defs[1].s = NULL;
+		kfree(geth);
+	}
+	return status;
+}

drivers/usb/gadget/u_ether.h

@@ -80,4 +80,7 @@ void gether_cleanup(void);
 struct net_device *gether_connect(struct gether *);
 void gether_disconnect(struct gether *);
 
+/* each configuration may bind one instance of an ethernet link */
+int geth_bind_config(struct usb_configuration *c, u8 ethaddr[ETH_ALEN]);
+
 #endif /* __U_ETHER_H */