wusb: add the USB wusb-cbaf driver

Add a driver for cable based associated of (Wireless) USB devices.

Signed-off-by: David Vrabel <david.vrabel@csr.com>

2 files changed, 623 insertions, 1 deletions

diff --git a/drivers/usb/wusbcore/Makefile b/drivers/usb/wusbcore/Makefile
index ea1dbfca613..6504f42ca36 100644
--- a/drivers/usb/wusbcore/Makefile
+++ b/drivers/usb/wusbcore/Makefile
@@ -1,4 +1,4 @@
-obj-$(CONFIG_USB_WUSB)		+= wusbcore.o
+obj-$(CONFIG_USB_WUSB)		+= wusbcore.o wusb-cbaf.o
 
 wusbcore-objs := 	\
 	crypto.o	\
@@ -10,3 +10,5 @@ wusbcore-objs := 	\
 	reservation.o	\
 	security.o	\
 	wusbhc.o
+
+wusb-cbaf-objs := cbaf.o
diff --git a/drivers/usb/wusbcore/cbaf.c b/drivers/usb/wusbcore/cbaf.c
new file mode 100644
index 00000000000..584eabe274b
--- /dev/null
+++ b/drivers/usb/wusbcore/cbaf.c
@@ -0,0 +1,620 @@
+/*
+ * Wireless USB - Cable Based Association
+ *
+ *
+ * Copyright (C) 2006 Intel Corporation
+ * Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License version
+ * 2 as published by the Free Software Foundation.
+ *
+ * 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., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ *
+ *
+ * WUSB devices have to be paired (authenticated in WUSB lingo) so
+ * that they can connect to the system.
+ *
+ * One way of pairing is using CBA-Cable Based Authentication, devices
+ * that can connect via wired or wireless USB. First time you plug
+ * them with a cable, pairing is done between host and device and
+ * subsequent times, you can connect wirelessly without having to
+ * pair. That's the idea.
+ *
+ * This driver does nothing Earth shattering. It just provides an
+ * interface to chat with the wire-connected device so we can get a
+ * CDID (device ID) that might have been previously associated to a
+ * CHID (host ID) and to set up a new <CHID,CDID,CK> triplet
+ * (connection context), with the CK being the secret, or connection
+ * key. This is the pairing data.
+ *
+ * When a device with the CBA capability connects, the probe routine
+ * just creates a bunch of sysfs files that a user space enumeration
+ * manager uses to allow it to connect wirelessly to the system or not.
+ *
+ * The process goes like this:
+ *
+ * 1. device plugs, cbaf is loaded, notifications happen
+ *
+ * 2. the connection manager sees a device with CBAF capability (the
+ *    wusb_{host_info,cdid,cc} files are in /sys/device/blah/OURDEVICE).
+ *
+ * 3. CM (connection manager) writes the CHID (host ID) and a host
+ *    name into the wusb_host_info file. This gets sent to the device.
+ *
+ * 4. CM cats the wusb_cdid file; this asks the device if it has any
+ *    CDID associated to the CHDI we just wrote before. If it does, it
+ *    is printed, along with the device 'friendly name' and the band
+ *    groups the device supports.
+ *
+ * 5. CM looks up its database
+ *
+ * 5.1  If it has a matching CHID,CDID entry, the device has been
+ *      authorized before (paired). Now we can optionally ask the user
+ *      if he wants to allow the device to connect. Then we generate a
+ *      new CDID and CK, send it to the device and update the database
+ *      (writing to the wusb_cc file so they are uploaded to the device).
+ *
+ * 5.2  If the CDID is zero (or we didn't find a matching CDID in our
+ *      database), we assume the device is not known. We ask the user
+ *      if s/he wants to allow the device to be connected wirelessly
+ *      to the system. If nope, nothing else is done (FIXME: maybe
+ *      send a zero CDID to clean up our CHID?). If yes, we generate
+ *      random CDID and CKs (and write them to the wusb_cc file so
+ *      they are uploaded to the device).
+ *
+ * 6. device is unplugged
+ *
+ * When the device tries to connect wirelessly, it will present it's
+ * CDID to the WUSB host controller with ID CHID, which will query the
+ * database. If found, the host will (with a 4way handshake) challenge
+ * the device to demonstrate it has the CK secret key (from our
+ * database) without actually exchanging it. Once satisfied, crypto
+ * keys are derived from the CK, the device is connected and all
+ * communication is crypted.
+ *
+ *
+ * NOTES ABOUT THE IMPLEMENTATION
+ *
+ * The descriptors sent back and forth use this horrible format from
+ * hell on which each field is actually a field ID, field length and
+ * then the field itself. How stupid can that get, taking into account
+ * the structures are defined by the spec?? oh well.
+ *
+ *
+ * FIXME: we don't provide a way to tell the device the pairing failed
+ *        (ie: send a CC_DATA_FAIL). Should add some day.
+ */
+#include <linux/module.h>
+#include <linux/ctype.h>
+#include <linux/version.h>
+#include <linux/usb.h>
+#include <linux/interrupt.h>
+#include <linux/delay.h>
+#include <linux/random.h>
+#include <linux/mutex.h>
+#include <linux/uwb.h>
+#include <linux/usb/wusb.h>
+#include <linux/usb/association.h>
+
+#undef D_LOCAL
+#define D_LOCAL 6
+#include <linux/uwb/debug.h>
+
+/* An instance of a Cable-Based-Association-Framework device */
+struct cbaf {
+	struct usb_device *usb_dev;
+	struct usb_interface *usb_iface;
+	void *buffer;
+	size_t buffer_size;
+
+	struct wusb_ckhdid chid;/* Host Information */
+	char host_name[65];	/* max length:
+					Assoc Models Suplement 1.0[T4-7] */
+	u16 host_band_groups;
+
+	struct wusb_ckhdid cdid;/* Device Information */
+	char device_name[65];	/* max length:
+					Assoc Models Suplement 1.0[T4-7] */
+	u16 device_band_groups;
+	struct wusb_ckhdid ck;	/* Connection Key */
+};
+
+/*
+ * Verify that a CBAF USB-interface has what we need
+ *
+ * (like we care, we are going to fail the enumeration if not :)
+ *
+ * FIXME: ugly function, need to split
+ */
+static int cbaf_check(struct cbaf *cbaf)
+{
+	int result;
+	struct device *dev = &cbaf->usb_iface->dev;
+	struct wusb_cbaf_assoc_info *assoc_info;
+	struct wusb_cbaf_assoc_request *assoc_request;
+	size_t assoc_size;
+	void *itr, *top;
+	unsigned ar_index;
+	int ar_rhi_idx = -1, ar_assoc_idx = -1;
+
+	result = usb_control_msg(
+		cbaf->usb_dev, usb_rcvctrlpipe(cbaf->usb_dev, 0),
+		CBAF_REQ_GET_ASSOCIATION_INFORMATION,
+		USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE,
+		0, cbaf->usb_iface->cur_altsetting->desc.bInterfaceNumber,
+		cbaf->buffer, cbaf->buffer_size, 1000 /* FIXME: arbitrary */);
+	if (result < 0) {
+		dev_err(dev, "cannot get available association types: %d\n",
+			result);
+		goto error_get_assoc_types;
+	}
+	assoc_info = cbaf->buffer;
+	if (result < sizeof(*assoc_info)) {
+		dev_err(dev, "not enough data to decode association info "
+			"header (%zu vs %zu bytes required)\n",
+			(size_t)result, sizeof(*assoc_info));
+		goto error_bad_header;
+	}
+	assoc_size = le16_to_cpu(assoc_info->Length);
+	if (result < assoc_size) {
+		dev_err(dev, "not enough data to decode association info "
+			"(%zu vs %zu bytes required)\n",
+			(size_t)assoc_size, sizeof(*assoc_info));
+		goto error_bad_data;
+	}
+	/*
+	 * From now on, we just verify, but won't error out unless we
+	 * don't find the AR_TYPE_WUSB_{RETRIEVE_HOST_INFO,ASSOCIATE}
+	 * types.
+	 */
+	ar_index = 0;
+	itr = cbaf->buffer + sizeof(*assoc_info);
+	top = cbaf->buffer + assoc_size;
+	d_printf(1, dev, "Found %u association requests (%zu bytes)\n",
+		 assoc_info->NumAssociationRequests, assoc_size);
+	while (itr < top) {
+		u16 ar_type, ar_subtype;
+		u32 ar_size;
+		const char *ar_name;
+
+		assoc_request = itr;
+		if (top - itr < sizeof(*assoc_request)) {
+			dev_err(dev, "not enough data to decode associaton "
+				"request (%zu vs %zu bytes needed)\n",
+				top - itr, sizeof(*assoc_request));
+			break;
+		}
+		ar_type = le16_to_cpu(assoc_request->AssociationTypeId);
+		ar_subtype = le16_to_cpu(assoc_request->AssociationSubTypeId);
+		ar_size = le32_to_cpu(assoc_request->AssociationTypeInfoSize);
+		switch (ar_type) {
+		case AR_TYPE_WUSB:
+			/* Verify we have what is mandated by AMS1.0 */
+			switch (ar_subtype) {
+			case AR_TYPE_WUSB_RETRIEVE_HOST_INFO:
+				ar_name = "retrieve_host_info";
+				ar_rhi_idx = ar_index;
+				break;
+			case AR_TYPE_WUSB_ASSOCIATE:
+				/* send assoc data */
+				ar_name = "associate";
+				ar_assoc_idx = ar_index;
+				break;
+			default:
+				ar_name = "unknown";
+			};
+			break;
+		default:
+			ar_name = "unknown";
+		};
+		d_printf(1, dev, "association request #%02u: 0x%04x/%04x "
+			 "(%zu bytes): %s\n",
+			 assoc_request->AssociationDataIndex, ar_type,
+			 ar_subtype, (size_t)ar_size, ar_name);
+
+		itr += sizeof(*assoc_request);
+		ar_index++;
+	}
+	if (ar_rhi_idx == -1) {
+		dev_err(dev, "Missing RETRIEVE_HOST_INFO association "
+			"request\n");
+		goto error_bad_reqs;
+	}
+	if (ar_assoc_idx == -1) {
+		dev_err(dev, "Missing ASSOCIATE association request\n");
+		goto error_bad_reqs;
+	}
+	return 0;
+
+error_bad_header:
+error_bad_data:
+error_bad_reqs:
+error_get_assoc_types:
+	return -EINVAL;
+}
+
+static const struct wusb_cbaf_host_info cbaf_host_info_defaults = {
+	.AssociationTypeId_hdr    = WUSB_AR_AssociationTypeId,
+	.AssociationTypeId    	  = cpu_to_le16(AR_TYPE_WUSB),
+	.AssociationSubTypeId_hdr = WUSB_AR_AssociationSubTypeId,
+	.AssociationSubTypeId = cpu_to_le16(AR_TYPE_WUSB_RETRIEVE_HOST_INFO),
+	.CHID_hdr                 = WUSB_AR_CHID,
+	.LangID_hdr               = WUSB_AR_LangID,
+	.HostFriendlyName_hdr     = WUSB_AR_HostFriendlyName,
+};
+
+/* Send WUSB host information (CHID and name) to a CBAF device */
+static int cbaf_send_host_info(struct cbaf *cbaf)
+{
+	struct wusb_cbaf_host_info *hi;
+	size_t hi_size;
+
+	hi = cbaf->buffer;
+	memset(hi, 0, sizeof(*hi));
+	*hi = cbaf_host_info_defaults;
+	hi->CHID = cbaf->chid;
+	hi->LangID = 0;	/* FIXME: I guess... */
+	strncpy(hi->HostFriendlyName, cbaf->host_name,
+		hi->HostFriendlyName_hdr.len);
+	hi->HostFriendlyName_hdr.len =
+				cpu_to_le16(strlen(hi->HostFriendlyName));
+	hi_size = sizeof(*hi) + strlen(hi->HostFriendlyName);
+	return usb_control_msg(cbaf->usb_dev, usb_sndctrlpipe(cbaf->usb_dev, 0),
+			CBAF_REQ_SET_ASSOCIATION_RESPONSE,
+			USB_DIR_OUT | USB_TYPE_CLASS | USB_RECIP_INTERFACE,
+			0x0101,
+			cbaf->usb_iface->cur_altsetting->desc.bInterfaceNumber,
+			hi, hi_size, 1000 /* FIXME: arbitrary */);
+}
+
+/* Show current CHID info we have set from user space */
+static ssize_t cbaf_wusb_host_info_show(struct device *dev,
+					struct device_attribute *attr,
+					char *buf)
+{
+	struct usb_interface *iface = to_usb_interface(dev);
+	struct cbaf *cbaf = usb_get_intfdata(iface);
+	char pr_chid[WUSB_CKHDID_STRSIZE];
+
+	ckhdid_printf(pr_chid, sizeof(pr_chid), &cbaf->chid);
+	return scnprintf(buf, PAGE_SIZE, "CHID: %s\nName: %s\n",
+			 pr_chid, cbaf->host_name);
+}
+
+/*
+ * Get a host info CHID from user space and send it to the device.
+ *
+ * The user can recover a CC from the device associated to that CHID
+ * by cat'ing wusb_connection_context.
+ */
+static ssize_t cbaf_wusb_host_info_store(struct device *dev,
+					 struct device_attribute *attr,
+					 const char *buf, size_t size)
+{
+	ssize_t result;
+	struct usb_interface *iface = to_usb_interface(dev);
+	struct cbaf *cbaf = usb_get_intfdata(iface);
+
+	result = sscanf(buf,
+			"%02hhx %02hhx %02hhx %02hhx "
+			"%02hhx %02hhx %02hhx %02hhx "
+			"%02hhx %02hhx %02hhx %02hhx "
+			"%02hhx %02hhx %02hhx %02hhx "
+			"%04hx %64s\n",
+			&cbaf->chid.data[0] , &cbaf->chid.data[1],
+			&cbaf->chid.data[2] , &cbaf->chid.data[3],
+			&cbaf->chid.data[4] , &cbaf->chid.data[5],
+			&cbaf->chid.data[6] , &cbaf->chid.data[7],
+			&cbaf->chid.data[8] , &cbaf->chid.data[9],
+			&cbaf->chid.data[10], &cbaf->chid.data[11],
+			&cbaf->chid.data[12], &cbaf->chid.data[13],
+			&cbaf->chid.data[14], &cbaf->chid.data[15],
+			&cbaf->host_band_groups, cbaf->host_name);
+	if (result != 18) {
+		dev_err(dev, "Unrecognized CHID (need 16 8-bit hex digits, "
+			"a 16 bit hex band group mask "
+			"and a host name, got only %d)\n", (int)result);
+		return -EINVAL;
+	}
+	result = cbaf_send_host_info(cbaf);
+	if (result < 0)
+		dev_err(dev, "Couldn't send host information to device: %d\n",
+			(int)result);
+	else
+		d_printf(1, dev, "HI sent, wusb_cc can be read now\n");
+	return result < 0 ? result : size;
+}
+static DEVICE_ATTR(wusb_host_info, 0600, cbaf_wusb_host_info_show,
+					 cbaf_wusb_host_info_store);
+
+static const struct wusb_cbaf_device_info cbaf_device_info_defaults = {
+	.Length_hdr               = WUSB_AR_Length,
+	.CDID_hdr                 = WUSB_AR_CDID,
+	.BandGroups_hdr           = WUSB_AR_BandGroups,
+	.LangID_hdr               = WUSB_AR_LangID,
+	.DeviceFriendlyName_hdr   = WUSB_AR_DeviceFriendlyName,
+};
+
+/*
+ * Get device's information (CDID) associated to CHID
+ *
+ * The device will return it's information (CDID, name, bandgroups)
+ * associated to the CHID we have set before, or 0 CDID and default
+ * name and bandgroup if no CHID set or unknown.
+ */
+static int cbaf_cdid_get(struct cbaf *cbaf)
+{
+	int result;
+	struct device *dev = &cbaf->usb_iface->dev;
+	struct wusb_cbaf_device_info *di;
+	size_t needed, dev_name_size;
+
+	di = cbaf->buffer;
+	result = usb_control_msg(
+		cbaf->usb_dev, usb_rcvctrlpipe(cbaf->usb_dev, 0),
+		CBAF_REQ_GET_ASSOCIATION_REQUEST,
+		USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE,
+		0x0200, cbaf->usb_iface->cur_altsetting->desc.bInterfaceNumber,
+		di, cbaf->buffer_size, 1000 /* FIXME: arbitrary */);
+	if (result < 0) {
+		dev_err(dev, "Cannot request device information: %d\n", result);
+		goto error_req_di;
+	}
+	needed = result < sizeof(*di) ? sizeof(*di) : le32_to_cpu(di->Length);
+	if (result < needed) {
+		dev_err(dev, "Not enough data in DEVICE_INFO reply (%zu vs "
+			"%zu bytes needed)\n", (size_t)result, needed);
+		goto error_bad_di;
+	}
+	cbaf->cdid = di->CDID;
+	dev_name_size = le16_to_cpu(di->DeviceFriendlyName_hdr.len);
+	dev_name_size = dev_name_size > 65 - 1 ? 65 - 1 : dev_name_size;
+	memcpy(cbaf->device_name, di->DeviceFriendlyName, dev_name_size);
+	cbaf->device_name[dev_name_size] = 0;
+	cbaf->device_band_groups = le16_to_cpu(di->BandGroups);
+	result = 0;
+error_req_di:
+error_bad_di:
+	return result;
+}
+
+/*
+ * Get device information and print it to sysfs
+ *
+ * See cbaf_cdid_get()
+ */
+static ssize_t cbaf_wusb_cdid_show(struct device *dev,
+				   struct device_attribute *attr, char *buf)
+{
+	ssize_t result;
+	struct usb_interface *iface = to_usb_interface(dev);
+	struct cbaf *cbaf = usb_get_intfdata(iface);
+	char pr_cdid[WUSB_CKHDID_STRSIZE];
+
+	result = cbaf_cdid_get(cbaf);
+	if (result < 0) {
+		dev_err(dev, "Cannot read device information: %d\n",
+			(int)result);
+		goto error_get_di;
+	}
+	ckhdid_printf(pr_cdid, sizeof(pr_cdid), &cbaf->cdid);
+	result = scnprintf(buf, PAGE_SIZE,
+			   "CDID: %s\nName: %s\nBand_groups: 0x%04x\n",
+			   pr_cdid, cbaf->device_name,
+			   cbaf->device_band_groups);
+error_get_di:
+	return result;
+}
+static DEVICE_ATTR(wusb_cdid, 0600, cbaf_wusb_cdid_show, NULL);
+
+static const struct wusb_cbaf_cc_data cbaf_cc_data_defaults = {
+	.AssociationTypeId_hdr    = WUSB_AR_AssociationTypeId,
+	.AssociationTypeId    	  = cpu_to_le16(AR_TYPE_WUSB),
+	.AssociationSubTypeId_hdr = WUSB_AR_AssociationSubTypeId,
+	.AssociationSubTypeId     = cpu_to_le16(AR_TYPE_WUSB_ASSOCIATE),
+	.Length_hdr               = WUSB_AR_Length,
+	.Length               	  = cpu_to_le32(sizeof(struct wusb_cbaf_cc_data)),
+	.ConnectionContext_hdr    = WUSB_AR_ConnectionContext,
+	.BandGroups_hdr           = WUSB_AR_BandGroups,
+};
+
+static const struct wusb_cbaf_cc_data_fail cbaf_cc_data_fail_defaults = {
+	.AssociationTypeId_hdr    = WUSB_AR_AssociationTypeId,
+	.AssociationSubTypeId_hdr = WUSB_AR_AssociationSubTypeId,
+	.Length_hdr               = WUSB_AR_Length,
+	.AssociationStatus_hdr    = WUSB_AR_AssociationStatus,
+};
+
+/*
+ * Send a new CC to the device
+ *
+ * So we update the CK and send the whole thing to the device
+ */
+static int cbaf_cc_upload(struct cbaf *cbaf)
+{
+	int result;
+	struct device *dev = &cbaf->usb_iface->dev;
+	struct wusb_cbaf_cc_data *ccd;
+	char pr_cdid[WUSB_CKHDID_STRSIZE];
+
+	ccd =  cbaf->buffer;
+	*ccd = cbaf_cc_data_defaults;
+	ccd->CHID = cbaf->chid;
+	ccd->CDID = cbaf->cdid;
+	ccd->CK = cbaf->ck;
+	ccd->BandGroups = cpu_to_le16(cbaf->host_band_groups);
+	result = usb_control_msg(
+		cbaf->usb_dev, usb_sndctrlpipe(cbaf->usb_dev, 0),
+		CBAF_REQ_SET_ASSOCIATION_RESPONSE,
+		USB_DIR_OUT | USB_TYPE_CLASS | USB_RECIP_INTERFACE,
+		0x0201, cbaf->usb_iface->cur_altsetting->desc.bInterfaceNumber,
+		ccd, sizeof(*ccd), 1000 /* FIXME: arbitrary */);
+	d_printf(1, dev, "Uploaded CC:\n");
+	ckhdid_printf(pr_cdid, sizeof(pr_cdid), &ccd->CHID);
+	d_printf(1, dev, "  CHID       %s\n", pr_cdid);
+	ckhdid_printf(pr_cdid, sizeof(pr_cdid), &ccd->CDID);
+	d_printf(1, dev, "  CDID       %s\n", pr_cdid);
+	ckhdid_printf(pr_cdid, sizeof(pr_cdid), &ccd->CK);
+	d_printf(1, dev, "  CK         %s\n", pr_cdid);
+	d_printf(1, dev, "  bandgroups 0x%04x\n", cbaf->host_band_groups);
+	return result;
+}
+
+/*
+ * Send a new CC to the device
+ *
+ * We take the CDID and CK from user space, the rest from the info we
+ * set with host_info.
+ */
+static ssize_t cbaf_wusb_cc_store(struct device *dev,
+				  struct device_attribute *attr,
+				  const char *buf, size_t size)
+{
+	ssize_t result;
+	struct usb_interface *iface = to_usb_interface(dev);
+	struct cbaf *cbaf = usb_get_intfdata(iface);
+
+	result = sscanf(buf,
+			"CDID: %02hhx %02hhx %02hhx %02hhx "
+			"%02hhx %02hhx %02hhx %02hhx "
+			"%02hhx %02hhx %02hhx %02hhx "
+			"%02hhx %02hhx %02hhx %02hhx\n"
+			"CK: %02hhx %02hhx %02hhx %02hhx "
+			"%02hhx %02hhx %02hhx %02hhx "
+			"%02hhx %02hhx %02hhx %02hhx "
+			"%02hhx %02hhx %02hhx %02hhx\n",
+			&cbaf->cdid.data[0] , &cbaf->cdid.data[1],
+			&cbaf->cdid.data[2] , &cbaf->cdid.data[3],
+			&cbaf->cdid.data[4] , &cbaf->cdid.data[5],
+			&cbaf->cdid.data[6] , &cbaf->cdid.data[7],
+			&cbaf->cdid.data[8] , &cbaf->cdid.data[9],
+			&cbaf->cdid.data[10], &cbaf->cdid.data[11],
+			&cbaf->cdid.data[12], &cbaf->cdid.data[13],
+			&cbaf->cdid.data[14], &cbaf->cdid.data[15],
+
+			&cbaf->ck.data[0] , &cbaf->ck.data[1],
+			&cbaf->ck.data[2] , &cbaf->ck.data[3],
+			&cbaf->ck.data[4] , &cbaf->ck.data[5],
+			&cbaf->ck.data[6] , &cbaf->ck.data[7],
+			&cbaf->ck.data[8] , &cbaf->ck.data[9],
+			&cbaf->ck.data[10], &cbaf->ck.data[11],
+			&cbaf->ck.data[12], &cbaf->ck.data[13],
+			&cbaf->ck.data[14], &cbaf->ck.data[15]);
+	if (result != 32) {
+		dev_err(dev, "Unrecognized CHID/CK (need 32 8-bit "
+			"hex digits, got only %d)\n", (int)result);
+		return -EINVAL;
+	}
+	result = cbaf_cc_upload(cbaf);
+	if (result < 0)
+		dev_err(dev, "Couldn't upload connection context: %d\n",
+			(int)result);
+	else
+		d_printf(1, dev, "Connection context uploaded\n");
+	return result < 0 ? result : size;
+}
+static DEVICE_ATTR(wusb_cc, 0600, NULL, cbaf_wusb_cc_store);
+
+static struct attribute *cbaf_dev_attrs[] = {
+	&dev_attr_wusb_host_info.attr,
+	&dev_attr_wusb_cdid.attr,
+	&dev_attr_wusb_cc.attr,
+	NULL,
+};
+
+static struct attribute_group cbaf_dev_attr_group = {
+	.name = NULL,	/* we want them in the same directory */
+	.attrs = cbaf_dev_attrs,
+};
+
+static int cbaf_probe(struct usb_interface *iface,
+		      const struct usb_device_id *id)
+{
+	int result;
+	struct cbaf *cbaf;
+	struct device *dev = &iface->dev;
+
+	result = -ENOMEM;
+	cbaf = kzalloc(sizeof(*cbaf), GFP_KERNEL);
+	if (cbaf == NULL) {
+		dev_err(dev, "Unable to allocate instance\n");
+		goto error_kzalloc;
+	}
+	cbaf->buffer = kmalloc(512, GFP_KERNEL);
+	if (cbaf->buffer == NULL)
+		goto error_kmalloc_buffer;
+	cbaf->buffer_size = 512;
+	cbaf->usb_dev = usb_get_dev(interface_to_usbdev(iface));
+	cbaf->usb_iface = usb_get_intf(iface);
+	result = cbaf_check(cbaf);
+	if (result < 0)
+		goto error_check;
+	result = sysfs_create_group(&dev->kobj, &cbaf_dev_attr_group);
+	if (result < 0) {
+		dev_err(dev, "Can't register sysfs attr group: %d\n", result);
+		goto error_create_group;
+	}
+	usb_set_intfdata(iface, cbaf);
+	d_printf(2, dev, "CBA attached\n");
+	return 0;
+
+error_create_group:
+error_check:
+	kfree(cbaf->buffer);
+error_kmalloc_buffer:
+	kfree(cbaf);
+error_kzalloc:
+	return result;
+}
+
+static void cbaf_disconnect(struct usb_interface *iface)
+{
+	struct cbaf *cbaf = usb_get_intfdata(iface);
+	struct device *dev = &iface->dev;
+	sysfs_remove_group(&dev->kobj, &cbaf_dev_attr_group);
+	usb_set_intfdata(iface, NULL);
+	usb_put_intf(iface);
+	kfree(cbaf->buffer);
+	/* paranoia: clean up crypto keys */
+	memset(cbaf, 0, sizeof(*cbaf));
+	kfree(cbaf);
+	d_printf(1, dev, "CBA detached\n");
+}
+
+static struct usb_device_id cbaf_id_table[] = {
+	{ USB_INTERFACE_INFO(0xef, 0x03, 0x01), },
+	{ },
+};
+MODULE_DEVICE_TABLE(usb, cbaf_id_table);
+
+static struct usb_driver cbaf_driver = {
+	.name =		"wusb-cbaf",
+	.id_table =	cbaf_id_table,
+	.probe =	cbaf_probe,
+	.disconnect =	cbaf_disconnect,
+};
+
+static int __init cbaf_driver_init(void)
+{
+	return usb_register(&cbaf_driver);
+}
+module_init(cbaf_driver_init);
+
+static void __exit cbaf_driver_exit(void)
+{
+	usb_deregister(&cbaf_driver);
+}
+module_exit(cbaf_driver_exit);
+
+MODULE_AUTHOR("Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>");
+MODULE_DESCRIPTION("Wireless USB Cable Based Association");
+MODULE_LICENSE("GPL");