Oliver Hartkopp | a1044e3 | 2010-12-02 10:57:59 +0000 | [diff] [blame] | 1 | /* |
| 2 | * slcan.c - serial line CAN interface driver (using tty line discipline) |
| 3 | * |
| 4 | * This file is derived from linux/drivers/net/slip.c |
| 5 | * |
| 6 | * slip.c Authors : Laurence Culhane <loz@holmes.demon.co.uk> |
| 7 | * Fred N. van Kempen <waltje@uwalt.nl.mugnet.org> |
| 8 | * slcan.c Author : Oliver Hartkopp <socketcan@hartkopp.net> |
| 9 | * |
| 10 | * This program is free software; you can redistribute it and/or modify it |
| 11 | * under the terms of the GNU General Public License as published by the |
| 12 | * Free Software Foundation; either version 2 of the License, or (at your |
| 13 | * option) any later version. |
| 14 | * |
| 15 | * This program is distributed in the hope that it will be useful, but |
| 16 | * WITHOUT ANY WARRANTY; without even the implied warranty of |
| 17 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 18 | * General Public License for more details. |
| 19 | * |
| 20 | * You should have received a copy of the GNU General Public License along |
| 21 | * with this program; if not, write to the Free Software Foundation, Inc., |
| 22 | * 59 Temple Place, Suite 330, Boston, MA 02111-1307. You can also get it |
| 23 | * at http://www.gnu.org/licenses/gpl.html |
| 24 | * |
| 25 | * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| 26 | * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| 27 | * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
| 28 | * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
| 29 | * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| 30 | * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| 31 | * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| 32 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| 33 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| 34 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| 35 | * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH |
| 36 | * DAMAGE. |
| 37 | * |
| 38 | * Send feedback to <socketcan-users@lists.berlios.de> |
| 39 | * |
| 40 | */ |
| 41 | |
| 42 | #include <linux/module.h> |
| 43 | #include <linux/moduleparam.h> |
| 44 | |
| 45 | #include <asm/system.h> |
| 46 | #include <linux/uaccess.h> |
| 47 | #include <linux/bitops.h> |
| 48 | #include <linux/string.h> |
| 49 | #include <linux/tty.h> |
| 50 | #include <linux/errno.h> |
| 51 | #include <linux/netdevice.h> |
| 52 | #include <linux/skbuff.h> |
| 53 | #include <linux/rtnetlink.h> |
| 54 | #include <linux/if_arp.h> |
| 55 | #include <linux/if_ether.h> |
David S. Miller | 84b3cdc | 2010-12-08 18:41:03 -0800 | [diff] [blame] | 56 | #include <linux/sched.h> |
Oliver Hartkopp | a1044e3 | 2010-12-02 10:57:59 +0000 | [diff] [blame] | 57 | #include <linux/delay.h> |
| 58 | #include <linux/init.h> |
| 59 | #include <linux/can.h> |
| 60 | |
| 61 | static __initdata const char banner[] = |
| 62 | KERN_INFO "slcan: serial line CAN interface driver\n"; |
| 63 | |
| 64 | MODULE_ALIAS_LDISC(N_SLCAN); |
| 65 | MODULE_DESCRIPTION("serial line CAN interface"); |
| 66 | MODULE_LICENSE("GPL"); |
| 67 | MODULE_AUTHOR("Oliver Hartkopp <socketcan@hartkopp.net>"); |
| 68 | |
| 69 | #define SLCAN_MAGIC 0x53CA |
| 70 | |
| 71 | static int maxdev = 10; /* MAX number of SLCAN channels; |
| 72 | This can be overridden with |
| 73 | insmod slcan.ko maxdev=nnn */ |
| 74 | module_param(maxdev, int, 0); |
| 75 | MODULE_PARM_DESC(maxdev, "Maximum number of slcan interfaces"); |
| 76 | |
| 77 | /* maximum rx buffer len: extended CAN frame with timestamp */ |
| 78 | #define SLC_MTU (sizeof("T1111222281122334455667788EA5F\r")+1) |
| 79 | |
| 80 | struct slcan { |
| 81 | int magic; |
| 82 | |
| 83 | /* Various fields. */ |
| 84 | struct tty_struct *tty; /* ptr to TTY structure */ |
| 85 | struct net_device *dev; /* easy for intr handling */ |
| 86 | spinlock_t lock; |
| 87 | |
| 88 | /* These are pointers to the malloc()ed frame buffers. */ |
| 89 | unsigned char rbuff[SLC_MTU]; /* receiver buffer */ |
| 90 | int rcount; /* received chars counter */ |
| 91 | unsigned char xbuff[SLC_MTU]; /* transmitter buffer */ |
| 92 | unsigned char *xhead; /* pointer to next XMIT byte */ |
| 93 | int xleft; /* bytes left in XMIT queue */ |
| 94 | |
| 95 | unsigned long flags; /* Flag values/ mode etc */ |
| 96 | #define SLF_INUSE 0 /* Channel in use */ |
| 97 | #define SLF_ERROR 1 /* Parity, etc. error */ |
| 98 | |
| 99 | unsigned char leased; |
| 100 | dev_t line; |
| 101 | pid_t pid; |
| 102 | }; |
| 103 | |
| 104 | static struct net_device **slcan_devs; |
| 105 | |
| 106 | /************************************************************************ |
| 107 | * SLCAN ENCAPSULATION FORMAT * |
| 108 | ************************************************************************/ |
| 109 | |
| 110 | /* |
| 111 | * A CAN frame has a can_id (11 bit standard frame format OR 29 bit extended |
| 112 | * frame format) a data length code (can_dlc) which can be from 0 to 8 |
| 113 | * and up to <can_dlc> data bytes as payload. |
| 114 | * Additionally a CAN frame may become a remote transmission frame if the |
| 115 | * RTR-bit is set. This causes another ECU to send a CAN frame with the |
| 116 | * given can_id. |
| 117 | * |
| 118 | * The SLCAN ASCII representation of these different frame types is: |
| 119 | * <type> <id> <dlc> <data>* |
| 120 | * |
| 121 | * Extended frames (29 bit) are defined by capital characters in the type. |
| 122 | * RTR frames are defined as 'r' types - normal frames have 't' type: |
| 123 | * t => 11 bit data frame |
| 124 | * r => 11 bit RTR frame |
| 125 | * T => 29 bit data frame |
| 126 | * R => 29 bit RTR frame |
| 127 | * |
| 128 | * The <id> is 3 (standard) or 8 (extended) bytes in ASCII Hex (base64). |
| 129 | * The <dlc> is a one byte ASCII number ('0' - '8') |
| 130 | * The <data> section has at much ASCII Hex bytes as defined by the <dlc> |
| 131 | * |
| 132 | * Examples: |
| 133 | * |
| 134 | * t1230 : can_id 0x123, can_dlc 0, no data |
| 135 | * t4563112233 : can_id 0x456, can_dlc 3, data 0x11 0x22 0x33 |
| 136 | * T12ABCDEF2AA55 : extended can_id 0x12ABCDEF, can_dlc 2, data 0xAA 0x55 |
| 137 | * r1230 : can_id 0x123, can_dlc 0, no data, remote transmission request |
| 138 | * |
| 139 | */ |
| 140 | |
| 141 | /************************************************************************ |
| 142 | * STANDARD SLCAN DECAPSULATION * |
| 143 | ************************************************************************/ |
| 144 | |
| 145 | static int asc2nibble(char c) |
| 146 | { |
| 147 | |
| 148 | if ((c >= '0') && (c <= '9')) |
| 149 | return c - '0'; |
| 150 | |
| 151 | if ((c >= 'A') && (c <= 'F')) |
| 152 | return c - 'A' + 10; |
| 153 | |
| 154 | if ((c >= 'a') && (c <= 'f')) |
| 155 | return c - 'a' + 10; |
| 156 | |
| 157 | return 16; /* error */ |
| 158 | } |
| 159 | |
| 160 | /* Send one completely decapsulated can_frame to the network layer */ |
| 161 | static void slc_bump(struct slcan *sl) |
| 162 | { |
| 163 | struct sk_buff *skb; |
| 164 | struct can_frame cf; |
| 165 | int i, dlc_pos, tmp; |
| 166 | unsigned long ultmp; |
| 167 | char cmd = sl->rbuff[0]; |
| 168 | |
| 169 | if ((cmd != 't') && (cmd != 'T') && (cmd != 'r') && (cmd != 'R')) |
| 170 | return; |
| 171 | |
| 172 | if (cmd & 0x20) /* tiny chars 'r' 't' => standard frame format */ |
| 173 | dlc_pos = 4; /* dlc position tiiid */ |
| 174 | else |
| 175 | dlc_pos = 9; /* dlc position Tiiiiiiiid */ |
| 176 | |
| 177 | if (!((sl->rbuff[dlc_pos] >= '0') && (sl->rbuff[dlc_pos] < '9'))) |
| 178 | return; |
| 179 | |
| 180 | cf.can_dlc = sl->rbuff[dlc_pos] - '0'; /* get can_dlc from ASCII val */ |
| 181 | |
| 182 | sl->rbuff[dlc_pos] = 0; /* terminate can_id string */ |
| 183 | |
| 184 | if (strict_strtoul(sl->rbuff+1, 16, &ultmp)) |
| 185 | return; |
| 186 | |
| 187 | cf.can_id = ultmp; |
| 188 | |
| 189 | if (!(cmd & 0x20)) /* NO tiny chars => extended frame format */ |
| 190 | cf.can_id |= CAN_EFF_FLAG; |
| 191 | |
| 192 | if ((cmd | 0x20) == 'r') /* RTR frame */ |
| 193 | cf.can_id |= CAN_RTR_FLAG; |
| 194 | |
| 195 | *(u64 *) (&cf.data) = 0; /* clear payload */ |
| 196 | |
| 197 | for (i = 0, dlc_pos++; i < cf.can_dlc; i++) { |
| 198 | |
| 199 | tmp = asc2nibble(sl->rbuff[dlc_pos++]); |
| 200 | if (tmp > 0x0F) |
| 201 | return; |
| 202 | cf.data[i] = (tmp << 4); |
| 203 | tmp = asc2nibble(sl->rbuff[dlc_pos++]); |
| 204 | if (tmp > 0x0F) |
| 205 | return; |
| 206 | cf.data[i] |= tmp; |
| 207 | } |
| 208 | |
| 209 | |
| 210 | skb = dev_alloc_skb(sizeof(struct can_frame)); |
| 211 | if (!skb) |
| 212 | return; |
| 213 | |
| 214 | skb->dev = sl->dev; |
| 215 | skb->protocol = htons(ETH_P_CAN); |
| 216 | skb->pkt_type = PACKET_BROADCAST; |
| 217 | skb->ip_summed = CHECKSUM_UNNECESSARY; |
| 218 | memcpy(skb_put(skb, sizeof(struct can_frame)), |
| 219 | &cf, sizeof(struct can_frame)); |
| 220 | netif_rx(skb); |
| 221 | |
| 222 | sl->dev->stats.rx_packets++; |
| 223 | sl->dev->stats.rx_bytes += cf.can_dlc; |
| 224 | } |
| 225 | |
| 226 | /* parse tty input stream */ |
| 227 | static void slcan_unesc(struct slcan *sl, unsigned char s) |
| 228 | { |
| 229 | |
| 230 | if ((s == '\r') || (s == '\a')) { /* CR or BEL ends the pdu */ |
| 231 | if (!test_and_clear_bit(SLF_ERROR, &sl->flags) && |
| 232 | (sl->rcount > 4)) { |
| 233 | slc_bump(sl); |
| 234 | } |
| 235 | sl->rcount = 0; |
| 236 | } else { |
| 237 | if (!test_bit(SLF_ERROR, &sl->flags)) { |
| 238 | if (sl->rcount < SLC_MTU) { |
| 239 | sl->rbuff[sl->rcount++] = s; |
| 240 | return; |
| 241 | } else { |
| 242 | sl->dev->stats.rx_over_errors++; |
| 243 | set_bit(SLF_ERROR, &sl->flags); |
| 244 | } |
| 245 | } |
| 246 | } |
| 247 | } |
| 248 | |
| 249 | /************************************************************************ |
| 250 | * STANDARD SLCAN ENCAPSULATION * |
| 251 | ************************************************************************/ |
| 252 | |
| 253 | /* Encapsulate one can_frame and stuff into a TTY queue. */ |
| 254 | static void slc_encaps(struct slcan *sl, struct can_frame *cf) |
| 255 | { |
| 256 | int actual, idx, i; |
| 257 | char cmd; |
| 258 | |
| 259 | if (cf->can_id & CAN_RTR_FLAG) |
| 260 | cmd = 'R'; /* becomes 'r' in standard frame format */ |
| 261 | else |
| 262 | cmd = 'T'; /* becomes 't' in standard frame format */ |
| 263 | |
| 264 | if (cf->can_id & CAN_EFF_FLAG) |
| 265 | sprintf(sl->xbuff, "%c%08X%d", cmd, |
| 266 | cf->can_id & CAN_EFF_MASK, cf->can_dlc); |
| 267 | else |
| 268 | sprintf(sl->xbuff, "%c%03X%d", cmd | 0x20, |
| 269 | cf->can_id & CAN_SFF_MASK, cf->can_dlc); |
| 270 | |
| 271 | idx = strlen(sl->xbuff); |
| 272 | |
| 273 | for (i = 0; i < cf->can_dlc; i++) |
| 274 | sprintf(&sl->xbuff[idx + 2*i], "%02X", cf->data[i]); |
| 275 | |
| 276 | strcat(sl->xbuff, "\r"); /* add terminating character */ |
| 277 | |
| 278 | /* Order of next two lines is *very* important. |
| 279 | * When we are sending a little amount of data, |
| 280 | * the transfer may be completed inside the ops->write() |
| 281 | * routine, because it's running with interrupts enabled. |
| 282 | * In this case we *never* got WRITE_WAKEUP event, |
| 283 | * if we did not request it before write operation. |
| 284 | * 14 Oct 1994 Dmitry Gorodchanin. |
| 285 | */ |
| 286 | set_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags); |
| 287 | actual = sl->tty->ops->write(sl->tty, sl->xbuff, strlen(sl->xbuff)); |
| 288 | sl->xleft = strlen(sl->xbuff) - actual; |
| 289 | sl->xhead = sl->xbuff + actual; |
| 290 | sl->dev->stats.tx_bytes += cf->can_dlc; |
| 291 | } |
| 292 | |
| 293 | /* |
| 294 | * Called by the driver when there's room for more data. If we have |
| 295 | * more packets to send, we send them here. |
| 296 | */ |
| 297 | static void slcan_write_wakeup(struct tty_struct *tty) |
| 298 | { |
| 299 | int actual; |
| 300 | struct slcan *sl = (struct slcan *) tty->disc_data; |
| 301 | |
| 302 | /* First make sure we're connected. */ |
| 303 | if (!sl || sl->magic != SLCAN_MAGIC || !netif_running(sl->dev)) |
| 304 | return; |
| 305 | |
| 306 | if (sl->xleft <= 0) { |
| 307 | /* Now serial buffer is almost free & we can start |
| 308 | * transmission of another packet */ |
| 309 | sl->dev->stats.tx_packets++; |
| 310 | clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); |
| 311 | netif_wake_queue(sl->dev); |
| 312 | return; |
| 313 | } |
| 314 | |
| 315 | actual = tty->ops->write(tty, sl->xhead, sl->xleft); |
| 316 | sl->xleft -= actual; |
| 317 | sl->xhead += actual; |
| 318 | } |
| 319 | |
| 320 | /* Send a can_frame to a TTY queue. */ |
| 321 | static netdev_tx_t slc_xmit(struct sk_buff *skb, struct net_device *dev) |
| 322 | { |
| 323 | struct slcan *sl = netdev_priv(dev); |
| 324 | |
| 325 | if (skb->len != sizeof(struct can_frame)) |
| 326 | goto out; |
| 327 | |
| 328 | spin_lock(&sl->lock); |
| 329 | if (!netif_running(dev)) { |
| 330 | spin_unlock(&sl->lock); |
| 331 | printk(KERN_WARNING "%s: xmit: iface is down\n", dev->name); |
| 332 | goto out; |
| 333 | } |
| 334 | if (sl->tty == NULL) { |
| 335 | spin_unlock(&sl->lock); |
| 336 | goto out; |
| 337 | } |
| 338 | |
| 339 | netif_stop_queue(sl->dev); |
| 340 | slc_encaps(sl, (struct can_frame *) skb->data); /* encaps & send */ |
| 341 | spin_unlock(&sl->lock); |
| 342 | |
| 343 | out: |
| 344 | kfree_skb(skb); |
| 345 | return NETDEV_TX_OK; |
| 346 | } |
| 347 | |
| 348 | |
| 349 | /****************************************** |
| 350 | * Routines looking at netdevice side. |
| 351 | ******************************************/ |
| 352 | |
| 353 | /* Netdevice UP -> DOWN routine */ |
| 354 | static int slc_close(struct net_device *dev) |
| 355 | { |
| 356 | struct slcan *sl = netdev_priv(dev); |
| 357 | |
| 358 | spin_lock_bh(&sl->lock); |
| 359 | if (sl->tty) { |
| 360 | /* TTY discipline is running. */ |
| 361 | clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags); |
| 362 | } |
| 363 | netif_stop_queue(dev); |
| 364 | sl->rcount = 0; |
| 365 | sl->xleft = 0; |
| 366 | spin_unlock_bh(&sl->lock); |
| 367 | |
| 368 | return 0; |
| 369 | } |
| 370 | |
| 371 | /* Netdevice DOWN -> UP routine */ |
| 372 | static int slc_open(struct net_device *dev) |
| 373 | { |
| 374 | struct slcan *sl = netdev_priv(dev); |
| 375 | |
| 376 | if (sl->tty == NULL) |
| 377 | return -ENODEV; |
| 378 | |
| 379 | sl->flags &= (1 << SLF_INUSE); |
| 380 | netif_start_queue(dev); |
| 381 | return 0; |
| 382 | } |
| 383 | |
| 384 | /* Hook the destructor so we can free slcan devs at the right point in time */ |
| 385 | static void slc_free_netdev(struct net_device *dev) |
| 386 | { |
| 387 | int i = dev->base_addr; |
| 388 | free_netdev(dev); |
| 389 | slcan_devs[i] = NULL; |
| 390 | } |
| 391 | |
| 392 | static const struct net_device_ops slc_netdev_ops = { |
| 393 | .ndo_open = slc_open, |
| 394 | .ndo_stop = slc_close, |
| 395 | .ndo_start_xmit = slc_xmit, |
| 396 | }; |
| 397 | |
| 398 | static void slc_setup(struct net_device *dev) |
| 399 | { |
| 400 | dev->netdev_ops = &slc_netdev_ops; |
| 401 | dev->destructor = slc_free_netdev; |
| 402 | |
| 403 | dev->hard_header_len = 0; |
| 404 | dev->addr_len = 0; |
| 405 | dev->tx_queue_len = 10; |
| 406 | |
| 407 | dev->mtu = sizeof(struct can_frame); |
| 408 | dev->type = ARPHRD_CAN; |
| 409 | |
| 410 | /* New-style flags. */ |
| 411 | dev->flags = IFF_NOARP; |
| 412 | dev->features = NETIF_F_NO_CSUM; |
| 413 | } |
| 414 | |
| 415 | /****************************************** |
| 416 | Routines looking at TTY side. |
| 417 | ******************************************/ |
| 418 | |
| 419 | /* |
| 420 | * Handle the 'receiver data ready' interrupt. |
| 421 | * This function is called by the 'tty_io' module in the kernel when |
| 422 | * a block of SLCAN data has been received, which can now be decapsulated |
| 423 | * and sent on to some IP layer for further processing. This will not |
| 424 | * be re-entered while running but other ldisc functions may be called |
| 425 | * in parallel |
| 426 | */ |
| 427 | |
| 428 | static void slcan_receive_buf(struct tty_struct *tty, |
| 429 | const unsigned char *cp, char *fp, int count) |
| 430 | { |
| 431 | struct slcan *sl = (struct slcan *) tty->disc_data; |
| 432 | |
| 433 | if (!sl || sl->magic != SLCAN_MAGIC || !netif_running(sl->dev)) |
| 434 | return; |
| 435 | |
| 436 | /* Read the characters out of the buffer */ |
| 437 | while (count--) { |
| 438 | if (fp && *fp++) { |
| 439 | if (!test_and_set_bit(SLF_ERROR, &sl->flags)) |
| 440 | sl->dev->stats.rx_errors++; |
| 441 | cp++; |
| 442 | continue; |
| 443 | } |
| 444 | slcan_unesc(sl, *cp++); |
| 445 | } |
| 446 | } |
| 447 | |
| 448 | /************************************ |
| 449 | * slcan_open helper routines. |
| 450 | ************************************/ |
| 451 | |
| 452 | /* Collect hanged up channels */ |
| 453 | static void slc_sync(void) |
| 454 | { |
| 455 | int i; |
| 456 | struct net_device *dev; |
| 457 | struct slcan *sl; |
| 458 | |
| 459 | for (i = 0; i < maxdev; i++) { |
| 460 | dev = slcan_devs[i]; |
| 461 | if (dev == NULL) |
| 462 | break; |
| 463 | |
| 464 | sl = netdev_priv(dev); |
| 465 | if (sl->tty || sl->leased) |
| 466 | continue; |
| 467 | if (dev->flags & IFF_UP) |
| 468 | dev_close(dev); |
| 469 | } |
| 470 | } |
| 471 | |
| 472 | /* Find a free SLCAN channel, and link in this `tty' line. */ |
| 473 | static struct slcan *slc_alloc(dev_t line) |
| 474 | { |
| 475 | int i; |
| 476 | struct net_device *dev = NULL; |
| 477 | struct slcan *sl; |
| 478 | |
| 479 | if (slcan_devs == NULL) |
| 480 | return NULL; /* Master array missing ! */ |
| 481 | |
| 482 | for (i = 0; i < maxdev; i++) { |
| 483 | dev = slcan_devs[i]; |
| 484 | if (dev == NULL) |
| 485 | break; |
| 486 | |
| 487 | } |
| 488 | |
| 489 | /* Sorry, too many, all slots in use */ |
| 490 | if (i >= maxdev) |
| 491 | return NULL; |
| 492 | |
| 493 | if (dev) { |
| 494 | sl = netdev_priv(dev); |
| 495 | if (test_bit(SLF_INUSE, &sl->flags)) { |
| 496 | unregister_netdevice(dev); |
| 497 | dev = NULL; |
| 498 | slcan_devs[i] = NULL; |
| 499 | } |
| 500 | } |
| 501 | |
| 502 | if (!dev) { |
| 503 | char name[IFNAMSIZ]; |
| 504 | sprintf(name, "slcan%d", i); |
| 505 | |
| 506 | dev = alloc_netdev(sizeof(*sl), name, slc_setup); |
| 507 | if (!dev) |
| 508 | return NULL; |
| 509 | dev->base_addr = i; |
| 510 | } |
| 511 | |
| 512 | sl = netdev_priv(dev); |
| 513 | |
| 514 | /* Initialize channel control data */ |
| 515 | sl->magic = SLCAN_MAGIC; |
| 516 | sl->dev = dev; |
| 517 | spin_lock_init(&sl->lock); |
| 518 | slcan_devs[i] = dev; |
| 519 | |
| 520 | return sl; |
| 521 | } |
| 522 | |
| 523 | /* |
| 524 | * Open the high-level part of the SLCAN channel. |
| 525 | * This function is called by the TTY module when the |
| 526 | * SLCAN line discipline is called for. Because we are |
| 527 | * sure the tty line exists, we only have to link it to |
| 528 | * a free SLCAN channel... |
| 529 | * |
| 530 | * Called in process context serialized from other ldisc calls. |
| 531 | */ |
| 532 | |
| 533 | static int slcan_open(struct tty_struct *tty) |
| 534 | { |
| 535 | struct slcan *sl; |
| 536 | int err; |
| 537 | |
| 538 | if (!capable(CAP_NET_ADMIN)) |
| 539 | return -EPERM; |
| 540 | |
| 541 | if (tty->ops->write == NULL) |
| 542 | return -EOPNOTSUPP; |
| 543 | |
| 544 | /* RTnetlink lock is misused here to serialize concurrent |
| 545 | opens of slcan channels. There are better ways, but it is |
| 546 | the simplest one. |
| 547 | */ |
| 548 | rtnl_lock(); |
| 549 | |
| 550 | /* Collect hanged up channels. */ |
| 551 | slc_sync(); |
| 552 | |
| 553 | sl = tty->disc_data; |
| 554 | |
| 555 | err = -EEXIST; |
| 556 | /* First make sure we're not already connected. */ |
| 557 | if (sl && sl->magic == SLCAN_MAGIC) |
| 558 | goto err_exit; |
| 559 | |
| 560 | /* OK. Find a free SLCAN channel to use. */ |
| 561 | err = -ENFILE; |
| 562 | sl = slc_alloc(tty_devnum(tty)); |
| 563 | if (sl == NULL) |
| 564 | goto err_exit; |
| 565 | |
| 566 | sl->tty = tty; |
| 567 | tty->disc_data = sl; |
| 568 | sl->line = tty_devnum(tty); |
| 569 | sl->pid = current->pid; |
| 570 | |
| 571 | if (!test_bit(SLF_INUSE, &sl->flags)) { |
| 572 | /* Perform the low-level SLCAN initialization. */ |
| 573 | sl->rcount = 0; |
| 574 | sl->xleft = 0; |
| 575 | |
| 576 | set_bit(SLF_INUSE, &sl->flags); |
| 577 | |
| 578 | err = register_netdevice(sl->dev); |
| 579 | if (err) |
| 580 | goto err_free_chan; |
| 581 | } |
| 582 | |
| 583 | /* Done. We have linked the TTY line to a channel. */ |
| 584 | rtnl_unlock(); |
| 585 | tty->receive_room = 65536; /* We don't flow control */ |
| 586 | return sl->dev->base_addr; |
| 587 | |
| 588 | err_free_chan: |
| 589 | sl->tty = NULL; |
| 590 | tty->disc_data = NULL; |
| 591 | clear_bit(SLF_INUSE, &sl->flags); |
| 592 | |
| 593 | err_exit: |
| 594 | rtnl_unlock(); |
| 595 | |
| 596 | /* Count references from TTY module */ |
| 597 | return err; |
| 598 | } |
| 599 | |
| 600 | /* |
| 601 | * Close down a SLCAN channel. |
| 602 | * This means flushing out any pending queues, and then returning. This |
| 603 | * call is serialized against other ldisc functions. |
| 604 | * |
| 605 | * We also use this method for a hangup event. |
| 606 | */ |
| 607 | |
| 608 | static void slcan_close(struct tty_struct *tty) |
| 609 | { |
| 610 | struct slcan *sl = (struct slcan *) tty->disc_data; |
| 611 | |
| 612 | /* First make sure we're connected. */ |
| 613 | if (!sl || sl->magic != SLCAN_MAGIC || sl->tty != tty) |
| 614 | return; |
| 615 | |
| 616 | tty->disc_data = NULL; |
| 617 | sl->tty = NULL; |
| 618 | if (!sl->leased) |
| 619 | sl->line = 0; |
| 620 | |
| 621 | /* Flush network side */ |
| 622 | unregister_netdev(sl->dev); |
| 623 | /* This will complete via sl_free_netdev */ |
| 624 | } |
| 625 | |
| 626 | static int slcan_hangup(struct tty_struct *tty) |
| 627 | { |
| 628 | slcan_close(tty); |
| 629 | return 0; |
| 630 | } |
| 631 | |
| 632 | /* Perform I/O control on an active SLCAN channel. */ |
| 633 | static int slcan_ioctl(struct tty_struct *tty, struct file *file, |
| 634 | unsigned int cmd, unsigned long arg) |
| 635 | { |
| 636 | struct slcan *sl = (struct slcan *) tty->disc_data; |
| 637 | unsigned int tmp; |
| 638 | |
| 639 | /* First make sure we're connected. */ |
| 640 | if (!sl || sl->magic != SLCAN_MAGIC) |
| 641 | return -EINVAL; |
| 642 | |
| 643 | switch (cmd) { |
| 644 | case SIOCGIFNAME: |
| 645 | tmp = strlen(sl->dev->name) + 1; |
| 646 | if (copy_to_user((void __user *)arg, sl->dev->name, tmp)) |
| 647 | return -EFAULT; |
| 648 | return 0; |
| 649 | |
| 650 | case SIOCSIFHWADDR: |
| 651 | return -EINVAL; |
| 652 | |
| 653 | default: |
| 654 | return tty_mode_ioctl(tty, file, cmd, arg); |
| 655 | } |
| 656 | } |
| 657 | |
| 658 | static struct tty_ldisc_ops slc_ldisc = { |
| 659 | .owner = THIS_MODULE, |
| 660 | .magic = TTY_LDISC_MAGIC, |
| 661 | .name = "slcan", |
| 662 | .open = slcan_open, |
| 663 | .close = slcan_close, |
| 664 | .hangup = slcan_hangup, |
| 665 | .ioctl = slcan_ioctl, |
| 666 | .receive_buf = slcan_receive_buf, |
| 667 | .write_wakeup = slcan_write_wakeup, |
| 668 | }; |
| 669 | |
| 670 | static int __init slcan_init(void) |
| 671 | { |
| 672 | int status; |
| 673 | |
| 674 | if (maxdev < 4) |
| 675 | maxdev = 4; /* Sanity */ |
| 676 | |
| 677 | printk(banner); |
| 678 | printk(KERN_INFO "slcan: %d dynamic interface channels.\n", maxdev); |
| 679 | |
| 680 | slcan_devs = kzalloc(sizeof(struct net_device *)*maxdev, GFP_KERNEL); |
| 681 | if (!slcan_devs) { |
| 682 | printk(KERN_ERR "slcan: can't allocate slcan device array!\n"); |
| 683 | return -ENOMEM; |
| 684 | } |
| 685 | |
| 686 | /* Fill in our line protocol discipline, and register it */ |
| 687 | status = tty_register_ldisc(N_SLCAN, &slc_ldisc); |
| 688 | if (status) { |
| 689 | printk(KERN_ERR "slcan: can't register line discipline\n"); |
| 690 | kfree(slcan_devs); |
| 691 | } |
| 692 | return status; |
| 693 | } |
| 694 | |
| 695 | static void __exit slcan_exit(void) |
| 696 | { |
| 697 | int i; |
| 698 | struct net_device *dev; |
| 699 | struct slcan *sl; |
| 700 | unsigned long timeout = jiffies + HZ; |
| 701 | int busy = 0; |
| 702 | |
| 703 | if (slcan_devs == NULL) |
| 704 | return; |
| 705 | |
| 706 | /* First of all: check for active disciplines and hangup them. |
| 707 | */ |
| 708 | do { |
| 709 | if (busy) |
| 710 | msleep_interruptible(100); |
| 711 | |
| 712 | busy = 0; |
| 713 | for (i = 0; i < maxdev; i++) { |
| 714 | dev = slcan_devs[i]; |
| 715 | if (!dev) |
| 716 | continue; |
| 717 | sl = netdev_priv(dev); |
| 718 | spin_lock_bh(&sl->lock); |
| 719 | if (sl->tty) { |
| 720 | busy++; |
| 721 | tty_hangup(sl->tty); |
| 722 | } |
| 723 | spin_unlock_bh(&sl->lock); |
| 724 | } |
| 725 | } while (busy && time_before(jiffies, timeout)); |
| 726 | |
| 727 | /* FIXME: hangup is async so we should wait when doing this second |
| 728 | phase */ |
| 729 | |
| 730 | for (i = 0; i < maxdev; i++) { |
| 731 | dev = slcan_devs[i]; |
| 732 | if (!dev) |
| 733 | continue; |
| 734 | slcan_devs[i] = NULL; |
| 735 | |
| 736 | sl = netdev_priv(dev); |
| 737 | if (sl->tty) { |
| 738 | printk(KERN_ERR "%s: tty discipline still running\n", |
| 739 | dev->name); |
| 740 | /* Intentionally leak the control block. */ |
| 741 | dev->destructor = NULL; |
| 742 | } |
| 743 | |
| 744 | unregister_netdev(dev); |
| 745 | } |
| 746 | |
| 747 | kfree(slcan_devs); |
| 748 | slcan_devs = NULL; |
| 749 | |
| 750 | i = tty_unregister_ldisc(N_SLCAN); |
| 751 | if (i) |
| 752 | printk(KERN_ERR "slcan: can't unregister ldisc (err %d)\n", i); |
| 753 | } |
| 754 | |
| 755 | module_init(slcan_init); |
| 756 | module_exit(slcan_exit); |