drivers/uwb/wlp/txrx.c

   1 /*
   2  * WiMedia Logical Link Control Protocol (WLP)
   3  * Message exchange infrastructure
   4  *
   5  * Copyright (C) 2007 Intel Corporation
   6  * Reinette Chatre <reinette.chatre@intel.com>
   7  *
   8  * This program is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU General Public License version
  10  * 2 as published by the Free Software Foundation.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  20  * 02110-1301, USA.
  21  *
  22  *
  23  * FIXME: Docs
  24  *
  25  */
  26
  27 #include <linux/etherdevice.h>
  28 #include <linux/wlp.h>
  29 #define D_LOCAL 5
  30 #include <linux/uwb/debug.h>
  31 #include "wlp-internal.h"
  32
  33
  34 /**
  35  * Direct incoming association msg to correct parsing routine
  36  *
  37  * We only expect D1, E1, C1, C3 messages as new. All other incoming
  38  * association messages should form part of an established session that is
  39  * handled elsewhere.
  40  * The handling of these messages often require calling sleeping functions
  41  * - this cannot be done in interrupt context. We use the kernel's
  42  * workqueue to handle these messages.
  43  */
  44 static
  45 void wlp_direct_assoc_frame(struct wlp *wlp, struct sk_buff *skb,
  46                            struct uwb_dev_addr *src)
  47 {
  48         struct device *dev = &wlp->rc->uwb_dev.dev;
  49         struct wlp_frame_assoc *assoc = (void *) skb->data;
  50         struct wlp_assoc_frame_ctx *frame_ctx;
  51         d_fnstart(5, dev, "wlp %p, skb %p\n", wlp, skb);
  52         frame_ctx = kmalloc(sizeof(*frame_ctx), GFP_ATOMIC);
  53         if (frame_ctx == NULL) {
  54                 dev_err(dev, "WLP: Unable to allocate memory for association "
  55                         "frame handling.\n");
  56                 kfree_skb(skb);
  57                 goto out;
  58         }
  59         frame_ctx->wlp = wlp;
  60         frame_ctx->skb = skb;
  61         frame_ctx->src = *src;
  62         switch (assoc->type) {
  63         case WLP_ASSOC_D1:
  64                 d_printf(5, dev, "Received a D1 frame.\n");
  65                 INIT_WORK(&frame_ctx->ws, wlp_handle_d1_frame);
  66                 schedule_work(&frame_ctx->ws);
  67                 break;
  68         case WLP_ASSOC_E1:
  69                 d_printf(5, dev, "Received a E1 frame. FIXME?\n");
  70                 kfree_skb(skb); /* Temporary until we handle it */
  71                 kfree(frame_ctx); /* Temporary until we handle it */
  72                 break;
  73         case WLP_ASSOC_C1:
  74                 d_printf(5, dev, "Received a C1 frame.\n");
  75                 INIT_WORK(&frame_ctx->ws, wlp_handle_c1_frame);
  76                 schedule_work(&frame_ctx->ws);
  77                 break;
  78         case WLP_ASSOC_C3:
  79                 d_printf(5, dev, "Received a C3 frame.\n");
  80                 INIT_WORK(&frame_ctx->ws, wlp_handle_c3_frame);
  81                 schedule_work(&frame_ctx->ws);
  82                 break;
  83         default:
  84                 dev_err(dev, "Received unexpected association frame. "
  85                         "Type = %d \n", assoc->type);
  86                 kfree_skb(skb);
  87                 kfree(frame_ctx);
  88                 break;
  89         }
  90 out:
  91         d_fnend(5, dev, "wlp %p\n", wlp);
  92 }
  93
  94 /**
  95  * Process incoming association frame
  96  *
  97  * Although it could be possible to deal with some incoming association
  98  * messages without creating a new session we are keeping things simple. We
  99  * do not accept new association messages if there is a session in progress
 100  * and the messages do not belong to that session.
 101  *
 102  * If an association message arrives that causes the creation of a session
 103  * (WLP_ASSOC_E1) while we are in the process of creating a session then we
 104  * rely on the neighbor mutex to protect the data. That is, the new session
 105  * will not be started until the previous is completed.
 106  */
 107 static
 108 void wlp_receive_assoc_frame(struct wlp *wlp, struct sk_buff *skb,
 109                              struct uwb_dev_addr *src)
 110 {
 111         struct device *dev = &wlp->rc->uwb_dev.dev;
 112         struct wlp_frame_assoc *assoc = (void *) skb->data;
 113         struct wlp_session *session = wlp->session;
 114         u8 version;
 115         d_fnstart(5, dev, "wlp %p, skb %p\n", wlp, skb);
 116
 117         if (wlp_get_version(wlp, &assoc->version, &version,
 118                             sizeof(assoc->version)) < 0)
 119                 goto error;
 120         if (version != WLP_VERSION) {
 121                 dev_err(dev, "Unsupported WLP version in association "
 122                         "message.\n");
 123                 goto error;
 124         }
 125         if (session != NULL) {
 126                 /* Function that created this session is still holding the
 127                  * &wlp->mutex to protect this session. */
 128                 if (assoc->type == session->exp_message ||
 129                     assoc->type == WLP_ASSOC_F0) {
 130                         if (!memcmp(&session->neighbor_addr, src,
 131                                    sizeof(*src))) {
 132                                 session->data = skb;
 133                                 (session->cb)(wlp);
 134                         } else {
 135                                 dev_err(dev, "Received expected message from "
 136                                         "unexpected source.  Expected message "
 137                                         "%d or F0 from %02x:%02x, but received "
 138                                         "it from %02x:%02x. Dropping.\n",
 139                                         session->exp_message,
 140                                         session->neighbor_addr.data[1],
 141                                         session->neighbor_addr.data[0],
 142                                         src->data[1], src->data[0]);
 143                                 goto error;
 144                         }
 145                 } else {
 146                         dev_err(dev, "Association already in progress. "
 147                                 "Dropping.\n");
 148                         goto error;
 149                 }
 150         } else {
 151                 wlp_direct_assoc_frame(wlp, skb, src);
 152         }
 153         d_fnend(5, dev, "wlp %p\n", wlp);
 154         return;
 155 error:
 156         kfree_skb(skb);
 157         d_fnend(5, dev, "wlp %p\n", wlp);
 158 }
 159
 160 /**
 161  * Verify incoming frame is from connected neighbor, prep to pass to WLP client
 162  *
 163  * Verification proceeds according to WLP 0.99 [7.3.1]. The source address
 164  * is used to determine which neighbor is sending the frame and the WSS tag
 165  * is used to know to which WSS the frame belongs (we only support one WSS
 166  * so this test is straight forward).
 167  * With the WSS found we need to ensure that we are connected before
 168  * allowing the exchange of data frames.
 169  */
 170 static
 171 int wlp_verify_prep_rx_frame(struct wlp *wlp, struct sk_buff *skb,
 172                              struct uwb_dev_addr *src)
 173 {
 174         struct device *dev = &wlp->rc->uwb_dev.dev;
 175         int result = -EINVAL;
 176         struct wlp_eda_node eda_entry;
 177         struct wlp_frame_std_abbrv_hdr *hdr = (void *) skb->data;
 178
 179         d_fnstart(6, dev, "wlp %p, skb %p \n", wlp, skb);
 180         /*verify*/
 181         result = wlp_copy_eda_node(&wlp->eda, src, &eda_entry);
 182         if (result < 0) {
 183                 if (printk_ratelimit())
 184                         dev_err(dev, "WLP: Incoming frame is from unknown "
 185                                 "neighbor %02x:%02x.\n", src->data[1],
 186                                 src->data[0]);
 187                 goto out;
 188         }
 189         if (hdr->tag != eda_entry.tag) {
 190                 if (printk_ratelimit())
 191                         dev_err(dev, "WLP: Tag of incoming frame from "
 192                                 "%02x:%02x does not match expected tag. "
 193                                 "Received 0x%02x, expected 0x%02x. \n",
 194                                 src->data[1], src->data[0], hdr->tag,
 195                                 eda_entry.tag);
 196                 result = -EINVAL;
 197                 goto out;
 198         }
 199         if (eda_entry.state != WLP_WSS_CONNECTED) {
 200                 if (printk_ratelimit())
 201                         dev_err(dev, "WLP: Incoming frame from "
 202                                 "%02x:%02x does is not from connected WSS.\n",
 203                                 src->data[1], src->data[0]);
 204                 result = -EINVAL;
 205                 goto out;
 206         }
 207         /*prep*/
 208         skb_pull(skb, sizeof(*hdr));
 209 out:
 210         d_fnend(6, dev, "wlp %p, skb %p, result = %d \n", wlp, skb, result);
 211         return result;
 212 }
 213
 214 /**
 215  * Receive a WLP frame from device
 216  *
 217  * @returns: 1 if calling function should free the skb
 218  *           0 if it successfully handled skb and freed it
 219  *           0 if error occured, will free skb in this case
 220  */
 221 int wlp_receive_frame(struct device *dev, struct wlp *wlp, struct sk_buff *skb,
 222                       struct uwb_dev_addr *src)
 223 {
 224         unsigned len = skb->len;
 225         void *ptr = skb->data;
 226         struct wlp_frame_hdr *hdr;
 227         int result = 0;
 228
 229         d_fnstart(6, dev, "skb (%p), len (%u)\n", skb, len);
 230         if (len < sizeof(*hdr)) {
 231                 dev_err(dev, "Not enough data to parse WLP header.\n");
 232                 result = -EINVAL;
 233                 goto out;
 234         }
 235         hdr = ptr;
 236         d_dump(6, dev, hdr, sizeof(*hdr));
 237         if (le16_to_cpu(hdr->mux_hdr) != WLP_PROTOCOL_ID) {
 238                 dev_err(dev, "Not a WLP frame type.\n");
 239                 result = -EINVAL;
 240                 goto out;
 241         }
 242         switch (hdr->type) {
 243         case WLP_FRAME_STANDARD:
 244                 if (len < sizeof(struct wlp_frame_std_abbrv_hdr)) {
 245                         dev_err(dev, "Not enough data to parse Standard "
 246                                 "WLP header.\n");
 247                         goto out;
 248                 }
 249                 result = wlp_verify_prep_rx_frame(wlp, skb, src);
 250                 if (result < 0) {
 251                         if (printk_ratelimit())
 252                                 dev_err(dev, "WLP: Verification of frame "
 253                                         "from neighbor %02x:%02x failed.\n",
 254                                         src->data[1], src->data[0]);
 255                         goto out;
 256                 }
 257                 result = 1;
 258                 break;
 259         case WLP_FRAME_ABBREVIATED:
 260                 dev_err(dev, "Abbreviated frame received. FIXME?\n");
 261                 kfree_skb(skb);
 262                 break;
 263         case WLP_FRAME_CONTROL:
 264                 dev_err(dev, "Control frame received. FIXME?\n");
 265                 kfree_skb(skb);
 266                 break;
 267         case WLP_FRAME_ASSOCIATION:
 268                 if (len < sizeof(struct wlp_frame_assoc)) {
 269                         dev_err(dev, "Not enough data to parse Association "
 270                                 "WLP header.\n");
 271                         goto out;
 272                 }
 273                 d_printf(5, dev, "Association frame received.\n");
 274                 wlp_receive_assoc_frame(wlp, skb, src);
 275                 break;
 276         default:
 277                 dev_err(dev, "Invalid frame received.\n");
 278                 result = -EINVAL;
 279                 break;
 280         }
 281 out:
 282         if (result < 0) {
 283                 kfree_skb(skb);
 284                 result = 0;
 285         }
 286         d_fnend(6, dev, "skb (%p)\n", skb);
 287         return result;
 288 }
 289 EXPORT_SYMBOL_GPL(wlp_receive_frame);
 290
 291
 292 /**
 293  * Verify frame from network stack, prepare for further transmission
 294  *
 295  * @skb:   the socket buffer that needs to be prepared for transmission (it
 296  *         is in need of a WLP header). If this is a broadcast frame we take
 297  *         over the entire transmission.
 298  *         If it is a unicast the WSS connection should already be established
 299  *         and transmission will be done by the calling function.
 300  * @dst:   On return this will contain the device address to which the
 301  *         frame is destined.
 302  * @returns: 0 on success no tx : WLP header sucessfully applied to skb buffer,
 303  *                                calling function can proceed with tx
 304  *           1 on success with tx : WLP will take over transmission of this
 305  *                                  frame
 306  *           <0 on error
 307  *
 308  * The network stack (WLP client) is attempting to transmit a frame. We can
 309  * only transmit data if a local WSS is at least active (connection will be
 310  * done here if this is a broadcast frame and neighbor also has the WSS
 311  * active).
 312  *
 313  * The frame can be either broadcast or unicast. Broadcast in a WSS is
 314  * supported via multicast, but we don't support multicast yet (until
 315  * devices start to support MAB IEs). If a broadcast frame needs to be
 316  * transmitted it is treated as a unicast frame to each neighbor. In this
 317  * case the WLP takes over transmission of the skb and returns 1
 318  * to the caller to indicate so. Also, in this case, if a neighbor has the
 319  * same WSS activated but is not connected then the WSS connection will be
 320  * done at this time. The neighbor's virtual address will be learned at
 321  * this time.
 322  *
 323  * The destination address in a unicast frame is the virtual address of the
 324  * neighbor. This address only becomes known when a WSS connection is
 325  * established. We thus rely on a broadcast frame to trigger the setup of
 326  * WSS connections to all neighbors before we are able to send unicast
 327  * frames to them. This seems reasonable as IP would usually use ARP first
 328  * before any unicast frames are sent.
 329  *
 330  * If we are already connected to the neighbor (neighbor's virtual address
 331  * is known) we just prepare the WLP header and the caller will continue to
 332  * send the frame.
 333  *
 334  * A failure in this function usually indicates something that cannot be
 335  * fixed automatically. So, if this function fails (@return < 0) the calling
 336  * function should not retry to send the frame as it will very likely keep
 337  * failing.
 338  *
 339  */
 340 int wlp_prepare_tx_frame(struct device *dev, struct wlp *wlp,
 341                          struct sk_buff *skb, struct uwb_dev_addr *dst)
 342 {
 343         int result = -EINVAL;
 344         struct ethhdr *eth_hdr = (void *) skb->data;
 345
 346         d_fnstart(6, dev, "wlp (%p), skb (%p) \n", wlp, skb);
 347         if (is_broadcast_ether_addr(eth_hdr->h_dest)) {
 348                 d_printf(6, dev, "WLP: handling broadcast frame. \n");
 349                 result = wlp_eda_for_each(&wlp->eda, wlp_wss_send_copy, skb);
 350                 if (result < 0) {
 351                         if (printk_ratelimit())
 352                                 dev_err(dev, "Unable to handle broadcast "
 353                                         "frame from WLP client.\n");
 354                         goto out;
 355                 }
 356                 dev_kfree_skb_irq(skb);
 357                 result = 1;
 358                 /* Frame will be transmitted by WLP. */
 359         } else {
 360                 d_printf(6, dev, "WLP: handling unicast frame. \n");
 361                 result = wlp_eda_for_virtual(&wlp->eda, eth_hdr->h_dest, dst,
 362                                              wlp_wss_prep_hdr, skb);
 363                 if (unlikely(result < 0)) {
 364                         if (printk_ratelimit())
 365                                 dev_err(dev, "Unable to prepare "
 366                                         "skb for transmission. \n");
 367                         goto out;
 368                 }
 369         }
 370 out:
 371         d_fnend(6, dev, "wlp (%p), skb (%p). result = %d \n", wlp, skb, result);
 372         return result;
 373 }
 374 EXPORT_SYMBOL_GPL(wlp_prepare_tx_frame);