1 /* 2 * Copyright (C) ST-Ericsson AB 2010 3 * Author: Sjur Brendeland 4 * License terms: GNU General Public License (GPL) version 2 5 */ 6 7 #include <linux/hardirq.h> 8 #include <linux/init.h> 9 #include <linux/module.h> 10 #include <linux/device.h> 11 #include <linux/types.h> 12 #include <linux/skbuff.h> 13 #include <linux/netdevice.h> 14 #include <linux/rtnetlink.h> 15 #include <linux/tty.h> 16 #include <linux/file.h> 17 #include <linux/if_arp.h> 18 #include <net/caif/caif_device.h> 19 #include <net/caif/cfcnfg.h> 20 #include <linux/err.h> 21 #include <linux/debugfs.h> 22 23 MODULE_LICENSE("GPL"); 24 MODULE_AUTHOR("Sjur Brendeland"); 25 MODULE_DESCRIPTION("CAIF serial device TTY line discipline"); 26 MODULE_LICENSE("GPL"); 27 MODULE_ALIAS_LDISC(N_CAIF); 28 29 #define SEND_QUEUE_LOW 10 30 #define SEND_QUEUE_HIGH 100 31 #define CAIF_SENDING 1 /* Bit 1 = 0x02*/ 32 #define CAIF_FLOW_OFF_SENT 4 /* Bit 4 = 0x10 */ 33 #define MAX_WRITE_CHUNK 4096 34 #define ON 1 35 #define OFF 0 36 #define CAIF_MAX_MTU 4096 37 38 static DEFINE_SPINLOCK(ser_lock); 39 static LIST_HEAD(ser_list); 40 static LIST_HEAD(ser_release_list); 41 42 static bool ser_loop; 43 module_param(ser_loop, bool, S_IRUGO); 44 MODULE_PARM_DESC(ser_loop, "Run in simulated loopback mode."); 45 46 static bool ser_use_stx = true; 47 module_param(ser_use_stx, bool, S_IRUGO); 48 MODULE_PARM_DESC(ser_use_stx, "STX enabled or not."); 49 50 static bool ser_use_fcs = true; 51 52 module_param(ser_use_fcs, bool, S_IRUGO); 53 MODULE_PARM_DESC(ser_use_fcs, "FCS enabled or not."); 54 55 static int ser_write_chunk = MAX_WRITE_CHUNK; 56 module_param(ser_write_chunk, int, S_IRUGO); 57 58 MODULE_PARM_DESC(ser_write_chunk, "Maximum size of data written to UART."); 59 60 static struct dentry *debugfsdir; 61 62 static int caif_net_open(struct net_device *dev); 63 static int caif_net_close(struct net_device *dev); 64 65 struct ser_device { 66 struct caif_dev_common common; 67 struct list_head node; 68 struct net_device *dev; 69 struct sk_buff_head head; 70 struct tty_struct *tty; 71 bool tx_started; 72 unsigned long state; 73 char *tty_name; 74 #ifdef CONFIG_DEBUG_FS 75 struct dentry *debugfs_tty_dir; 76 struct debugfs_blob_wrapper tx_blob; 77 struct debugfs_blob_wrapper rx_blob; 78 u8 rx_data[128]; 79 u8 tx_data[128]; 80 u8 tty_status; 81 82 #endif 83 }; 84 85 static void caifdev_setup(struct net_device *dev); 86 static void ldisc_tx_wakeup(struct tty_struct *tty); 87 #ifdef CONFIG_DEBUG_FS 88 static inline void update_tty_status(struct ser_device *ser) 89 { 90 ser->tty_status = 91 ser->tty->stopped << 5 | 92 ser->tty->flow_stopped << 3 | 93 ser->tty->packet << 2 | 94 ser->tty->port->low_latency << 1; 95 } 96 static inline void debugfs_init(struct ser_device *ser, struct tty_struct *tty) 97 { 98 ser->debugfs_tty_dir = 99 debugfs_create_dir(tty->name, debugfsdir); 100 if (!IS_ERR(ser->debugfs_tty_dir)) { 101 debugfs_create_blob("last_tx_msg", S_IRUSR, 102 ser->debugfs_tty_dir, 103 &ser->tx_blob); 104 105 debugfs_create_blob("last_rx_msg", S_IRUSR, 106 ser->debugfs_tty_dir, 107 &ser->rx_blob); 108 109 debugfs_create_x32("ser_state", S_IRUSR, 110 ser->debugfs_tty_dir, 111 (u32 *)&ser->state); 112 113 debugfs_create_x8("tty_status", S_IRUSR, 114 ser->debugfs_tty_dir, 115 &ser->tty_status); 116 117 } 118 ser->tx_blob.data = ser->tx_data; 119 ser->tx_blob.size = 0; 120 ser->rx_blob.data = ser->rx_data; 121 ser->rx_blob.size = 0; 122 } 123 124 static inline void debugfs_deinit(struct ser_device *ser) 125 { 126 debugfs_remove_recursive(ser->debugfs_tty_dir); 127 } 128 129 static inline void debugfs_rx(struct ser_device *ser, const u8 *data, int size) 130 { 131 if (size > sizeof(ser->rx_data)) 132 size = sizeof(ser->rx_data); 133 memcpy(ser->rx_data, data, size); 134 ser->rx_blob.data = ser->rx_data; 135 ser->rx_blob.size = size; 136 } 137 138 static inline void debugfs_tx(struct ser_device *ser, const u8 *data, int size) 139 { 140 if (size > sizeof(ser->tx_data)) 141 size = sizeof(ser->tx_data); 142 memcpy(ser->tx_data, data, size); 143 ser->tx_blob.data = ser->tx_data; 144 ser->tx_blob.size = size; 145 } 146 #else 147 static inline void debugfs_init(struct ser_device *ser, struct tty_struct *tty) 148 { 149 } 150 151 static inline void debugfs_deinit(struct ser_device *ser) 152 { 153 } 154 155 static inline void update_tty_status(struct ser_device *ser) 156 { 157 } 158 159 static inline void debugfs_rx(struct ser_device *ser, const u8 *data, int size) 160 { 161 } 162 163 static inline void debugfs_tx(struct ser_device *ser, const u8 *data, int size) 164 { 165 } 166 167 #endif 168 169 static void ldisc_receive(struct tty_struct *tty, const u8 *data, 170 char *flags, int count) 171 { 172 struct sk_buff *skb = NULL; 173 struct ser_device *ser; 174 int ret; 175 u8 *p; 176 177 ser = tty->disc_data; 178 179 /* 180 * NOTE: flags may contain information about break or overrun. 181 * This is not yet handled. 182 */ 183 184 185 /* 186 * Workaround for garbage at start of transmission, 187 * only enable if STX handling is not enabled. 188 */ 189 if (!ser->common.use_stx && !ser->tx_started) { 190 dev_info(&ser->dev->dev, 191 "Bytes received before initial transmission -" 192 "bytes discarded.\n"); 193 return; 194 } 195 196 BUG_ON(ser->dev == NULL); 197 198 /* Get a suitable caif packet and copy in data. */ 199 skb = netdev_alloc_skb(ser->dev, count+1); 200 if (skb == NULL) 201 return; 202 p = skb_put(skb, count); 203 memcpy(p, data, count); 204 205 skb->protocol = htons(ETH_P_CAIF); 206 skb_reset_mac_header(skb); 207 debugfs_rx(ser, data, count); 208 /* Push received packet up the stack. */ 209 ret = netif_rx_ni(skb); 210 if (!ret) { 211 ser->dev->stats.rx_packets++; 212 ser->dev->stats.rx_bytes += count; 213 } else 214 ++ser->dev->stats.rx_dropped; 215 update_tty_status(ser); 216 } 217 218 static int handle_tx(struct ser_device *ser) 219 { 220 struct tty_struct *tty; 221 struct sk_buff *skb; 222 int tty_wr, len, room; 223 224 tty = ser->tty; 225 ser->tx_started = true; 226 227 /* Enter critical section */ 228 if (test_and_set_bit(CAIF_SENDING, &ser->state)) 229 return 0; 230 231 /* skb_peek is safe because handle_tx is called after skb_queue_tail */ 232 while ((skb = skb_peek(&ser->head)) != NULL) { 233 234 /* Make sure you don't write too much */ 235 len = skb->len; 236 room = tty_write_room(tty); 237 if (!room) 238 break; 239 if (room > ser_write_chunk) 240 room = ser_write_chunk; 241 if (len > room) 242 len = room; 243 244 /* Write to tty or loopback */ 245 if (!ser_loop) { 246 tty_wr = tty->ops->write(tty, skb->data, len); 247 update_tty_status(ser); 248 } else { 249 tty_wr = len; 250 ldisc_receive(tty, skb->data, NULL, len); 251 } 252 ser->dev->stats.tx_packets++; 253 ser->dev->stats.tx_bytes += tty_wr; 254 255 /* Error on TTY ?! */ 256 if (tty_wr < 0) 257 goto error; 258 /* Reduce buffer written, and discard if empty */ 259 skb_pull(skb, tty_wr); 260 if (skb->len == 0) { 261 struct sk_buff *tmp = skb_dequeue(&ser->head); 262 WARN_ON(tmp != skb); 263 if (in_interrupt()) 264 dev_kfree_skb_irq(skb); 265 else 266 kfree_skb(skb); 267 } 268 } 269 /* Send flow off if queue is empty */ 270 if (ser->head.qlen <= SEND_QUEUE_LOW && 271 test_and_clear_bit(CAIF_FLOW_OFF_SENT, &ser->state) && 272 ser->common.flowctrl != NULL) 273 ser->common.flowctrl(ser->dev, ON); 274 clear_bit(CAIF_SENDING, &ser->state); 275 return 0; 276 error: 277 clear_bit(CAIF_SENDING, &ser->state); 278 return tty_wr; 279 } 280 281 static int caif_xmit(struct sk_buff *skb, struct net_device *dev) 282 { 283 struct ser_device *ser; 284 285 BUG_ON(dev == NULL); 286 ser = netdev_priv(dev); 287 288 /* Send flow off once, on high water mark */ 289 if (ser->head.qlen > SEND_QUEUE_HIGH && 290 !test_and_set_bit(CAIF_FLOW_OFF_SENT, &ser->state) && 291 ser->common.flowctrl != NULL) 292 293 ser->common.flowctrl(ser->dev, OFF); 294 295 skb_queue_tail(&ser->head, skb); 296 return handle_tx(ser); 297 } 298 299 300 static void ldisc_tx_wakeup(struct tty_struct *tty) 301 { 302 struct ser_device *ser; 303 304 ser = tty->disc_data; 305 BUG_ON(ser == NULL); 306 WARN_ON(ser->tty != tty); 307 handle_tx(ser); 308 } 309 310 311 static void ser_release(struct work_struct *work) 312 { 313 struct list_head list; 314 struct ser_device *ser, *tmp; 315 316 spin_lock(&ser_lock); 317 list_replace_init(&ser_release_list, &list); 318 spin_unlock(&ser_lock); 319 320 if (!list_empty(&list)) { 321 rtnl_lock(); 322 list_for_each_entry_safe(ser, tmp, &list, node) { 323 dev_close(ser->dev); 324 unregister_netdevice(ser->dev); 325 debugfs_deinit(ser); 326 } 327 rtnl_unlock(); 328 } 329 } 330 331 static DECLARE_WORK(ser_release_work, ser_release); 332 333 static int ldisc_open(struct tty_struct *tty) 334 { 335 struct ser_device *ser; 336 struct net_device *dev; 337 char name[64]; 338 int result; 339 340 /* No write no play */ 341 if (tty->ops->write == NULL) 342 return -EOPNOTSUPP; 343 if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_TTY_CONFIG)) 344 return -EPERM; 345 346 /* release devices to avoid name collision */ 347 ser_release(NULL); 348 349 result = snprintf(name, sizeof(name), "cf%s", tty->name); 350 if (result >= IFNAMSIZ) 351 return -EINVAL; 352 dev = alloc_netdev(sizeof(*ser), name, NET_NAME_UNKNOWN, 353 caifdev_setup); 354 if (!dev) 355 return -ENOMEM; 356 357 ser = netdev_priv(dev); 358 ser->tty = tty_kref_get(tty); 359 ser->dev = dev; 360 debugfs_init(ser, tty); 361 tty->receive_room = N_TTY_BUF_SIZE; 362 tty->disc_data = ser; 363 set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); 364 rtnl_lock(); 365 result = register_netdevice(dev); 366 if (result) { 367 rtnl_unlock(); 368 free_netdev(dev); 369 return -ENODEV; 370 } 371 372 spin_lock(&ser_lock); 373 list_add(&ser->node, &ser_list); 374 spin_unlock(&ser_lock); 375 rtnl_unlock(); 376 netif_stop_queue(dev); 377 update_tty_status(ser); 378 return 0; 379 } 380 381 static void ldisc_close(struct tty_struct *tty) 382 { 383 struct ser_device *ser = tty->disc_data; 384 385 tty_kref_put(ser->tty); 386 387 spin_lock(&ser_lock); 388 list_move(&ser->node, &ser_release_list); 389 spin_unlock(&ser_lock); 390 schedule_work(&ser_release_work); 391 } 392 393 /* The line discipline structure. */ 394 static struct tty_ldisc_ops caif_ldisc = { 395 .owner = THIS_MODULE, 396 .magic = TTY_LDISC_MAGIC, 397 .name = "n_caif", 398 .open = ldisc_open, 399 .close = ldisc_close, 400 .receive_buf = ldisc_receive, 401 .write_wakeup = ldisc_tx_wakeup 402 }; 403 404 static int register_ldisc(void) 405 { 406 int result; 407 408 result = tty_register_ldisc(N_CAIF, &caif_ldisc); 409 if (result < 0) { 410 pr_err("cannot register CAIF ldisc=%d err=%d\n", N_CAIF, 411 result); 412 return result; 413 } 414 return result; 415 } 416 static const struct net_device_ops netdev_ops = { 417 .ndo_open = caif_net_open, 418 .ndo_stop = caif_net_close, 419 .ndo_start_xmit = caif_xmit 420 }; 421 422 static void caifdev_setup(struct net_device *dev) 423 { 424 struct ser_device *serdev = netdev_priv(dev); 425 426 dev->features = 0; 427 dev->netdev_ops = &netdev_ops; 428 dev->type = ARPHRD_CAIF; 429 dev->flags = IFF_POINTOPOINT | IFF_NOARP; 430 dev->mtu = CAIF_MAX_MTU; 431 dev->tx_queue_len = 0; 432 dev->destructor = free_netdev; 433 skb_queue_head_init(&serdev->head); 434 serdev->common.link_select = CAIF_LINK_LOW_LATENCY; 435 serdev->common.use_frag = true; 436 serdev->common.use_stx = ser_use_stx; 437 serdev->common.use_fcs = ser_use_fcs; 438 serdev->dev = dev; 439 } 440 441 442 static int caif_net_open(struct net_device *dev) 443 { 444 netif_wake_queue(dev); 445 return 0; 446 } 447 448 static int caif_net_close(struct net_device *dev) 449 { 450 netif_stop_queue(dev); 451 return 0; 452 } 453 454 static int __init caif_ser_init(void) 455 { 456 int ret; 457 458 ret = register_ldisc(); 459 debugfsdir = debugfs_create_dir("caif_serial", NULL); 460 return ret; 461 } 462 463 static void __exit caif_ser_exit(void) 464 { 465 spin_lock(&ser_lock); 466 list_splice(&ser_list, &ser_release_list); 467 spin_unlock(&ser_lock); 468 ser_release(NULL); 469 cancel_work_sync(&ser_release_work); 470 tty_unregister_ldisc(N_CAIF); 471 debugfs_remove_recursive(debugfsdir); 472 } 473 474 module_init(caif_ser_init); 475 module_exit(caif_ser_exit); 476