wusb: wusb-cbaf (CBA driver) sysfs ABI simplification

Simplify the sysfs ABI of the wusb-cbaf (Cable Based Association)
driver: use one value per file and cause the write of the CHID to
fetch the CDID (instead of requiring a separate read).

Update the example wusb-cbaf script to work with this revised ABI.

Signed-off-by: Felipe Zimmerle <felipe.zimmerle@indt.org.br>
Signed-off-by: David Vrabel <david.vrabel@csr.com>

4 files changed, 350 insertions, 262 deletions

diff --git a/Documentation/usb/wusb-cbaf b/Documentation/usb/wusb-cbaf
index a385478ba12e..2e78b70f3adc 100644
--- a/Documentation/usb/wusb-cbaf
+++ b/Documentation/usb/wusb-cbaf
@@ -70,32 +70,42 @@ EOF
 # FIXME: CHID should come from a database :), band group from the host
 host_CHID="00 11 22 33 44 55 66 77 88 99 aa bb cc dd ee ff"
 host_band_group="0001"
-host_name="Linux-WUSB"
+host_name=$(hostname)
 
 devs="$(echo /sys/bus/usb/drivers/wusb-cbaf/[0-9]*)"
-hdevs="$(find /sys -name wusb_chid -printf "%h\n")"
+hdevs="$(for h in /sys/class/uwb_rc/*/wusbhc; do readlink -f $h; done)"
 
 result=0
 case $1 in
     start)
         for dev in ${2:-$hdevs}
           do
-          uwb_rc=$(find $(dirname $(dirname $dev)) -iname uwb_rc:uwb*)
-          if cat $uwb_rc/uwb_rc/beacon | grep -q "channel: -1"
+          uwb_rc=$(readlink -f $dev/uwb_rc)
+          if cat $uwb_rc/beacon | grep -q -- "-1"
               then
-              echo 13 0 | cat > $uwb_rc/uwb_rc/beacon
-              echo I: started beaconing on ch 13 in host $(basename $uwb_rc)
+              echo 13 0 > $uwb_rc/beacon
+              echo I: started beaconing on ch 13 on $(basename $uwb_rc) >&2
           fi
-          echo $host_CHID | cat > $dev/wusb_chid
-          echo I: started host $(basename $dev)
+          echo $host_CHID > $dev/wusb_chid
+          echo I: started host $(basename $dev) >&2
+        done
+        ;;
+    stop)
+        for dev in ${2:-$hdevs}
+          do
+          echo 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > $dev/wusb_chid
+          echo I: stopped host $(basename $dev) >&2
+          uwb_rc=$(readlink -f $dev/uwb_rc)
+          echo -1 | cat > $uwb_rc/beacon
+          echo I: stopped beaconing on $(basename $uwb_rc) >&2
         done
         ;;
     set-chid)
         shift
-        for dev in ${2:-$devs}
-          do
-          echo "${2:-$host_CHID}" "${3:-$host_band_group}" "${4:-$host_name}" \
-              | cat > $dev/wusb_host_info
+        for dev in ${2:-$devs}; do
+            echo "${4:-$host_name}" > $dev/wusb_host_name
+            echo "${3:-$host_band_group}" > $dev/wusb_host_band_groups
+            echo ${2:-$host_CHID} > $dev/wusb_chid
         done
         ;;
     get-cdid)
@@ -105,21 +115,17 @@ case $1 in
         done
         ;;
     set-cc)
-        for dev in ${2:-$devs}
-          do
-          shift
-          CDID="$(head --bytes=16 /dev/urandom  | od -tx1 -An)"
-          CK="$(head --bytes=16 /dev/urandom  | od -tx1 -An)"
-          cat > $dev/wusb_cc <<EOF
-CDID:$CDID
-CK:$CK
-EOF
-          cat <<EOF
-I: CC set
-CHID: $host_CHID
-CDID:$CDID
-CK:  $CK
-EOF
+        for dev in ${2:-$devs}; do
+            shift
+            CDID="$(head --bytes=16 /dev/urandom  | od -tx1 -An)"
+            CK="$(head --bytes=16 /dev/urandom  | od -tx1 -An)"
+            echo "$CDID" > $dev/wusb_cdid
+            echo "$CK" > $dev/wusb_ck
+
+            echo I: CC set >&2
+            echo "CHID: $(cat $dev/wusb_chid)"
+            echo "CDID:$CDID"
+            echo "CK:  $CK"
         done
         ;;
     help|h|--help|-h)
diff --git a/drivers/usb/wusbcore/Kconfig b/drivers/usb/wusbcore/Kconfig
index add077e5c5d0..4ea76693ad46 100644
--- a/drivers/usb/wusbcore/Kconfig
+++ b/drivers/usb/wusbcore/Kconfig
@@ -15,3 +15,26 @@ config USB_WUSB
 
           To compile this support select Y (built in). It is safe to
           select even if you don't have the hardware.
+
+config USB_WUSB_CBAF
+        tristate "Support WUSB Cable Based Association (CBA)"
+        depends on USB
+        help
+          Some WUSB devices support Cable Based Association. It's used to
+          enable the secure communication between the host and the
+          device.
+
+          Enable this option if your WUSB device must to be connected
+          via wired USB before establishing a wireless link.
+
+          It is safe to select even if you don't have a compatible
+          hardware.
+
+config USB_WUSB_CBAF_DEBUG
+        bool "Enable CBA debug messages"
+        depends on USB_WUSB_CBAF
+        help
+          Say Y here if you want the CBA to produce a bunch of debug messages
+          to the system log. Select this if you are having a problem with
+          CBA support and want to see more of what is going on.
+
diff --git a/drivers/usb/wusbcore/Makefile b/drivers/usb/wusbcore/Makefile
index 7a4d00724039..75f1ade66258 100644
--- a/drivers/usb/wusbcore/Makefile
+++ b/drivers/usb/wusbcore/Makefile
@@ -1,5 +1,7 @@
-obj-$(CONFIG_USB_WUSB)          += wusbcore.o wusb-cbaf.o
+obj-$(CONFIG_USB_WUSB)          += wusbcore.o
 obj-$(CONFIG_USB_HWA_HCD)       += wusb-wa.o
+obj-$(CONFIG_USB_WUSB_CBAF)     += wusb-cbaf.o
+
 
 wusbcore-objs :=        \
         crypto.o        \
@@ -18,3 +20,7 @@ wusb-wa-objs :=	wa-hc.o		\
                 wa-nep.o        \
                 wa-rpipe.o      \
                 wa-xfer.o
+
+ifeq ($(CONFIG_USB_WUSB_CBAF_DEBUG),y)
+EXTRA_CFLAGS += -DDEBUG
+endif
diff --git a/drivers/usb/wusbcore/cbaf.c b/drivers/usb/wusbcore/cbaf.c
index 584eabe274b3..ab4788d1785a 100644
--- a/drivers/usb/wusbcore/cbaf.c
+++ b/drivers/usb/wusbcore/cbaf.c
@@ -4,6 +4,7 @@
  *
  * Copyright (C) 2006 Intel Corporation
  * Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>
+ * Copyright (C) 2008 Cambridge Silicon Radio Ltd.
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License version
@@ -20,14 +21,13 @@
  * 02110-1301, USA.
  *
  *
- * WUSB devices have to be paired (authenticated in WUSB lingo) so
+ * WUSB devices have to be paired (associated 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.
+ * One way of pairing is using CBA-Cable Based Association. First
+ * time you plug the device with a cable, association is done between
+ * host and device and subsequent times, you can connect wirelessly
+ * without having to associate again. 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
@@ -42,56 +42,49 @@
  *
  * The process goes like this:
  *
- * 1. device plugs, cbaf is loaded, notifications happen
+ * 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).
+ * 2. The connection manager (CM) sees a device with CBAF capability
+ *    (the wusb_chid etc. files in /sys/devices/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.
+ * 3. The CM writes the host name, supported band groups, and the CHID
+ *    (host ID) into the wusb_host_name, wusb_host_band_groups and
+ *    wusb_chid files. These get sent to the device and the CDID (if
+ *    any) for this host is requested.
  *
- * 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.
+ * 4. The CM can verify that the device's supported band groups
+ *    (wusb_device_band_groups) are compatible with the host.
  *
- * 5. CM looks up its database
+ * 5. The CM reads the wusb_cdid file.
  *
- * 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).
+ * 6. The CM looks up its database
  *
- * 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).
+ * 6.1 If it has a matching CHID,CDID entry, the device has been
+ *     authorized before (paired) and nothing further needs to be
+ *     done.
  *
- * 6. device is unplugged
+ * 6.2 If the CDID is zero (or the CM doesn't find a matching CDID in
+ *     its database), the device is assumed to be not known.  The CM
+ *     may associate the host with device by: writing a randomly
+ *     generated CDID to wusb_cdid and then a random CK to wusb_ck
+ *     (this uploads the new CC to the device).
  *
- * 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.
+ *     CMD may choose to prompt the user before associating with a new
+ *     device.
  *
+ * 7. Device is unplugged.
  *
- * NOTES ABOUT THE IMPLEMENTATION
+ * When the device tries to connect wirelessly, it will present its
+ * CDID to the WUSB host controller.  The CM will query the
+ * database. If the CHID/CDID pair found, it will (with a 4-way
+ * 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 encrypted.
  *
- * 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.
+ * References:
+ *   [WUSB-AM] Association Models Supplement to the Certified Wireless
+ *             Universal Serial Bus Specification, version 1.0.
  */
 #include <linux/module.h>
 #include <linux/ctype.h>
@@ -105,9 +98,7 @@
 #include <linux/usb/wusb.h>
 #include <linux/usb/association.h>
 
-#undef D_LOCAL
-#define D_LOCAL 6
-#include <linux/uwb/debug.h>
+#define CBA_NAME_LEN 0x40 /* [WUSB-AM] table 4-7 */
 
 /* An instance of a Cable-Based-Association-Framework device */
 struct cbaf {
@@ -116,24 +107,27 @@ struct cbaf {
         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] */
+        struct wusb_ckhdid chid;
+        char host_name[CBA_NAME_LEN];
         u16 host_band_groups;
 
-        struct wusb_ckhdid cdid;/* Device Information */
-        char device_name[65];   /* max length:
-                                        Assoc Models Suplement 1.0[T4-7] */
+        struct wusb_ckhdid cdid;
+        char device_name[CBA_NAME_LEN];
         u16 device_band_groups;
-        struct wusb_ckhdid ck;  /* Connection Key */
+
+        struct wusb_ckhdid ck;
 };
 
 /*
  * Verify that a CBAF USB-interface has what we need
  *
- * (like we care, we are going to fail the enumeration if not :)
+ * According to [WUSB-AM], CBA devices should provide at least two
+ * interfaces:
+ *  - RETRIEVE_HOST_INFO
+ *  - ASSOCIATE
  *
- * FIXME: ugly function, need to split
+ * If the device doesn't provide these interfaces, we do not know how
+ * to deal with it.
  */
 static int cbaf_check(struct cbaf *cbaf)
 {
@@ -143,8 +137,7 @@ static int cbaf_check(struct cbaf *cbaf)
         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;
+        int ar_rhi = 0, ar_assoc = 0;
 
         result = usb_control_msg(
                 cbaf->usb_dev, usb_rcvctrlpipe(cbaf->usb_dev, 0),
@@ -153,93 +146,91 @@ static int cbaf_check(struct cbaf *cbaf)
                 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",
+                dev_err(dev, "Cannot get available association types: %d\n",
                         result);
-                goto error_get_assoc_types;
+                return result;
         }
+
         assoc_info = cbaf->buffer;
         if (result < sizeof(*assoc_info)) {
-                dev_err(dev, "not enough data to decode association 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;
+                return result;
         }
+
         assoc_size = le16_to_cpu(assoc_info->Length);
         if (result < assoc_size) {
-                dev_err(dev, "not enough data to decode association info "
+                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;
+                return result;
         }
         /*
          * 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",
+        dev_dbg(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 "
+                        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);
+                ar_name = "unknown";
+
                 switch (ar_type) {
                 case AR_TYPE_WUSB:
-                        /* Verify we have what is mandated by AMS1.0 */
+                        /* Verify we have what is mandated by [WUSB-AM]. */
                         switch (ar_subtype) {
                         case AR_TYPE_WUSB_RETRIEVE_HOST_INFO:
-                                ar_name = "retrieve_host_info";
-                                ar_rhi_idx = ar_index;
+                                ar_name = "RETRIEVE_HOST_INFO";
+                                ar_rhi = 1;
                                 break;
                         case AR_TYPE_WUSB_ASSOCIATE:
                                 /* send assoc data */
-                                ar_name = "associate";
-                                ar_assoc_idx = ar_index;
+                                ar_name = "ASSOCIATE";
+                                ar_assoc = 1;
                                 break;
-                        default:
-                                ar_name = "unknown";
                         };
                         break;
-                default:
-                        ar_name = "unknown";
                 };
-                d_printf(1, dev, "association request #%02u: 0x%04x/%04x "
+
+                dev_dbg(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) {
+
+        if (!ar_rhi) {
                 dev_err(dev, "Missing RETRIEVE_HOST_INFO association "
                         "request\n");
-                goto error_bad_reqs;
+                return -EINVAL;
         }
-        if (ar_assoc_idx == -1) {
+        if (!ar_assoc) {
                 dev_err(dev, "Missing ASSOCIATE association request\n");
-                goto error_bad_reqs;
+                return -EINVAL;
         }
-        return 0;
 
-error_bad_header:
-error_bad_data:
-error_bad_reqs:
-error_get_assoc_types:
-        return -EINVAL;
+        return 0;
 }
 
 static const struct wusb_cbaf_host_info cbaf_host_info_defaults = {
@@ -256,6 +247,7 @@ static const struct wusb_cbaf_host_info cbaf_host_info_defaults = {
 static int cbaf_send_host_info(struct cbaf *cbaf)
 {
         struct wusb_cbaf_host_info *hi;
+        size_t name_len;
         size_t hi_size;
 
         hi = cbaf->buffer;
@@ -263,11 +255,11 @@ static int cbaf_send_host_info(struct cbaf *cbaf)
         *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);
+        strlcpy(hi->HostFriendlyName, cbaf->host_name, CBA_NAME_LEN);
+        name_len = strlen(cbaf->host_name);
+        hi->HostFriendlyName_hdr.len = cpu_to_le16(name_len);
+        hi_size = sizeof(*hi) + name_len;
+
         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,
@@ -276,8 +268,47 @@ static int cbaf_send_host_info(struct cbaf *cbaf)
                         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,
+/*
+ * 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;
+
+        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);
+                return result;
+        }
+
+        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);
+                return result;
+        }
+
+        strlcpy(cbaf->device_name, di->DeviceFriendlyName, CBA_NAME_LEN);
+        cbaf->cdid = di->CDID;
+        cbaf->device_band_groups = le16_to_cpu(di->BandGroups);
+
+        return 0;
+}
+
+static ssize_t cbaf_wusb_chid_show(struct device *dev,
                                         struct device_attribute *attr,
                                         char *buf)
 {
@@ -286,17 +317,10 @@ static ssize_t cbaf_wusb_host_info_show(struct device *dev,
         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);
+        return scnprintf(buf, PAGE_SIZE, "%s\n", pr_chid);
 }
 
-/*
- * 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,
+static ssize_t cbaf_wusb_chid_store(struct device *dev,
                                          struct device_attribute *attr,
                                          const char *buf, size_t size)
 {
@@ -308,8 +332,7 @@ static ssize_t cbaf_wusb_host_info_store(struct device *dev,
                         "%02hhx %02hhx %02hhx %02hhx "
                         "%02hhx %02hhx %02hhx %02hhx "
                         "%02hhx %02hhx %02hhx %02hhx "
-                        "%02hhx %02hhx %02hhx %02hhx "
-                        "%04hx %64s\n",
+                        "%02hhx %02hhx %02hhx %02hhx",
                         &cbaf->chid.data[0] , &cbaf->chid.data[1],
                         &cbaf->chid.data[2] , &cbaf->chid.data[3],
                         &cbaf->chid.data[4] , &cbaf->chid.data[5],
@@ -317,24 +340,79 @@ static ssize_t cbaf_wusb_host_info_store(struct device *dev,
                         &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);
+                        &cbaf->chid.data[14], &cbaf->chid.data[15]);
+
+        if (result != 16)
                 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;
+                return result;
+        result = cbaf_cdid_get(cbaf);
+        if (result < 0)
+                return -result;
+        return size;
+}
+static DEVICE_ATTR(wusb_chid, 0600, cbaf_wusb_chid_show, cbaf_wusb_chid_store);
+
+static ssize_t cbaf_wusb_host_name_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);
+
+        return scnprintf(buf, PAGE_SIZE, "%s\n", cbaf->host_name);
+}
+
+static ssize_t cbaf_wusb_host_name_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, "%63s", cbaf->host_name);
+        if (result != 1)
+                return -EINVAL;
+
+        return size;
+}
+static DEVICE_ATTR(wusb_host_name, 0600, cbaf_wusb_host_name_show,
+                                         cbaf_wusb_host_name_store);
+
+static ssize_t cbaf_wusb_host_band_groups_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);
+
+        return scnprintf(buf, PAGE_SIZE, "0x%04x\n", cbaf->host_band_groups);
+}
+
+static ssize_t cbaf_wusb_host_band_groups_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);
+        u16 band_groups = 0;
+
+        result = sscanf(buf, "%04hx", &band_groups);
+        if (result != 1)
+                return -EINVAL;
+
+        cbaf->host_band_groups = band_groups;
+
+        return size;
 }
-static DEVICE_ATTR(wusb_host_info, 0600, cbaf_wusb_host_info_show,
-                                         cbaf_wusb_host_info_store);
+
+static DEVICE_ATTR(wusb_host_band_groups, 0600,
+                   cbaf_wusb_host_band_groups_show,
+                   cbaf_wusb_host_band_groups_store);
 
 static const struct wusb_cbaf_device_info cbaf_device_info_defaults = {
         .Length_hdr               = WUSB_AR_Length,
@@ -344,77 +422,72 @@ static const struct wusb_cbaf_device_info cbaf_device_info_defaults = {
         .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)
+static ssize_t cbaf_wusb_cdid_show(struct device *dev,
+                                   struct device_attribute *attr, char *buf)
 {
-        int result;
-        struct device *dev = &cbaf->usb_iface->dev;
-        struct wusb_cbaf_device_info *di;
-        size_t needed, dev_name_size;
+        struct usb_interface *iface = to_usb_interface(dev);
+        struct cbaf *cbaf = usb_get_intfdata(iface);
+        char pr_cdid[WUSB_CKHDID_STRSIZE];
 
-        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;
+        ckhdid_printf(pr_cdid, sizeof(pr_cdid), &cbaf->cdid);
+        return scnprintf(buf, PAGE_SIZE, "%s\n", pr_cdid);
 }
 
-/*
- * 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)
+static ssize_t cbaf_wusb_cdid_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);
-        char pr_cdid[WUSB_CKHDID_STRSIZE];
+        struct wusb_ckhdid cdid;
 
-        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;
+        result = sscanf(buf,
+                        "%02hhx %02hhx %02hhx %02hhx "
+                        "%02hhx %02hhx %02hhx %02hhx "
+                        "%02hhx %02hhx %02hhx %02hhx "
+                        "%02hhx %02hhx %02hhx %02hhx",
+                        &cdid.data[0] , &cdid.data[1],
+                        &cdid.data[2] , &cdid.data[3],
+                        &cdid.data[4] , &cdid.data[5],
+                        &cdid.data[6] , &cdid.data[7],
+                        &cdid.data[8] , &cdid.data[9],
+                        &cdid.data[10], &cdid.data[11],
+                        &cdid.data[12], &cdid.data[13],
+                        &cdid.data[14], &cdid.data[15]);
+        if (result != 16)
+                return -EINVAL;
+
+        cbaf->cdid = cdid;
+
+        return size;
+}
+static DEVICE_ATTR(wusb_cdid, 0600, cbaf_wusb_cdid_show, cbaf_wusb_cdid_store);
+
+static ssize_t cbaf_wusb_device_band_groups_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);
+
+        return scnprintf(buf, PAGE_SIZE, "0x%04x\n", cbaf->device_band_groups);
+}
+
+static DEVICE_ATTR(wusb_device_band_groups, 0600,
+                   cbaf_wusb_device_band_groups_show,
+                   NULL);
+
+static ssize_t cbaf_wusb_device_name_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);
+
+        return scnprintf(buf, PAGE_SIZE, "%s\n", cbaf->device_name);
 }
-static DEVICE_ATTR(wusb_cdid, 0600, cbaf_wusb_cdid_show, NULL);
+static DEVICE_ATTR(wusb_device_name, 0600, cbaf_wusb_device_name_show, NULL);
 
 static const struct wusb_cbaf_cc_data cbaf_cc_data_defaults = {
         .AssociationTypeId_hdr    = WUSB_AR_AssociationTypeId,
@@ -435,9 +508,7 @@ static const struct wusb_cbaf_cc_data_fail cbaf_cc_data_fail_defaults = {
 };
 
 /*
- * Send a new CC to the device
- *
- * So we update the CK and send the whole thing to the device
+ * Send a new CC to the device.
  */
 static int cbaf_cc_upload(struct cbaf *cbaf)
 {
@@ -452,30 +523,25 @@ static int cbaf_cc_upload(struct cbaf *cbaf)
         ccd->CDID = cbaf->cdid;
         ccd->CK = cbaf->ck;
         ccd->BandGroups = cpu_to_le16(cbaf->host_band_groups);
+
+        dev_dbg(dev, "Trying to upload CC:\n");
+        ckhdid_printf(pr_cdid, sizeof(pr_cdid), &ccd->CHID);
+        dev_dbg(dev, "  CHID       %s\n", pr_cdid);
+        ckhdid_printf(pr_cdid, sizeof(pr_cdid), &ccd->CDID);
+        dev_dbg(dev, "  CDID       %s\n", pr_cdid);
+        dev_dbg(dev, "  Bandgroups 0x%04x\n", 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,
+static ssize_t cbaf_wusb_ck_store(struct device *dev,
                                   struct device_attribute *attr,
                                   const char *buf, size_t size)
 {
@@ -484,23 +550,10 @@ static ssize_t cbaf_wusb_cc_store(struct device *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],
-
+                        "%02hhx %02hhx %02hhx %02hhx",
                         &cbaf->ck.data[0] , &cbaf->ck.data[1],
                         &cbaf->ck.data[2] , &cbaf->ck.data[3],
                         &cbaf->ck.data[4] , &cbaf->ck.data[5],
@@ -509,25 +562,25 @@ static ssize_t cbaf_wusb_cc_store(struct device *dev,
                         &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);
+        if (result != 16)
                 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;
+                return result;
+
+        return size;
 }
-static DEVICE_ATTR(wusb_cc, 0600, NULL, cbaf_wusb_cc_store);
+static DEVICE_ATTR(wusb_ck, 0600, NULL, cbaf_wusb_ck_store);
 
 static struct attribute *cbaf_dev_attrs[] = {
-        &dev_attr_wusb_host_info.attr,
+        &dev_attr_wusb_host_name.attr,
+        &dev_attr_wusb_host_band_groups.attr,
+        &dev_attr_wusb_chid.attr,
         &dev_attr_wusb_cdid.attr,
-        &dev_attr_wusb_cc.attr,
+        &dev_attr_wusb_device_name.attr,
+        &dev_attr_wusb_device_band_groups.attr,
+        &dev_attr_wusb_ck.attr,
         NULL,
 };
 
@@ -539,32 +592,33 @@ static struct attribute_group cbaf_dev_attr_group = {
 static int cbaf_probe(struct usb_interface *iface,
                       const struct usb_device_id *id)
 {
-        int result;
         struct cbaf *cbaf;
         struct device *dev = &iface->dev;
+        int result = -ENOMEM;
 
-        result = -ENOMEM;
         cbaf = kzalloc(sizeof(*cbaf), GFP_KERNEL);
-        if (cbaf == NULL) {
-                dev_err(dev, "Unable to allocate instance\n");
+        if (cbaf == NULL)
                 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)
+        if (result < 0) {
+                dev_err(dev, "This device is not WUSB-CBAF compliant"
+                        "and is not supported yet.\n");
                 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:
@@ -587,7 +641,6 @@ static void cbaf_disconnect(struct usb_interface *iface)
         /* 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[] = {