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