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, 0444); 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, 0444); 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, 0444); 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, 0444); 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", 0400, 101 ser->debugfs_tty_dir, 102 &ser->tx_blob); 103 104 debugfs_create_blob("last_rx_msg", 0400, 105 ser->debugfs_tty_dir, 106 &ser->rx_blob); 107 108 debugfs_create_x32("ser_state", 0400, 109 ser->debugfs_tty_dir, 110 (u32 *)&ser->state); 111 112 debugfs_create_x8("tty_status", 0400, 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; 174 175 ser = tty->disc_data; 176 177 /* 178 * NOTE: flags may contain information about break or overrun. 179 * This is not yet handled. 180 */ 181 182 183 /* 184 * Workaround for garbage at start of transmission, 185 * only enable if STX handling is not enabled. 186 */ 187 if (!ser->common.use_stx && !ser->tx_started) { 188 dev_info(&ser->dev->dev, 189 "Bytes received before initial transmission -" 190 "bytes discarded.\n"); 191 return; 192 } 193 194 BUG_ON(ser->dev == NULL); 195 196 /* Get a suitable caif packet and copy in data. */ 197 skb = netdev_alloc_skb(ser->dev, count+1); 198 if (skb == NULL) 199 return; 200 skb_put_data(skb, data, count); 201 202 skb->protocol = htons(ETH_P_CAIF); 203 skb_reset_mac_header(skb); 204 debugfs_rx(ser, data, count); 205 /* Push received packet up the stack. */ 206 ret = netif_rx_ni(skb); 207 if (!ret) { 208 ser->dev->stats.rx_packets++; 209 ser->dev->stats.rx_bytes += count; 210 } else 211 ++ser->dev->stats.rx_dropped; 212 update_tty_status(ser); 213 } 214 215 static int handle_tx(struct ser_device *ser) 216 { 217 struct tty_struct *tty; 218 struct sk_buff *skb; 219 int tty_wr, len, room; 220 221 tty = ser->tty; 222 ser->tx_started = true; 223 224 /* Enter critical section */ 225 if (test_and_set_bit(CAIF_SENDING, &ser->state)) 226 return 0; 227 228 /* skb_peek is safe because handle_tx is called after skb_queue_tail */ 229 while ((skb = skb_peek(&ser->head)) != NULL) { 230 231 /* Make sure you don't write too much */ 232 len = skb->len; 233 room = tty_write_room(tty); 234 if (!room) 235 break; 236 if (room > ser_write_chunk) 237 room = ser_write_chunk; 238 if (len > room) 239 len = room; 240 241 /* Write to tty or loopback */ 242 if (!ser_loop) { 243 tty_wr = tty->ops->write(tty, skb->data, len); 244 update_tty_status(ser); 245 } else { 246 tty_wr = len; 247 ldisc_receive(tty, skb->data, NULL, len); 248 } 249 ser->dev->stats.tx_packets++; 250 ser->dev->stats.tx_bytes += tty_wr; 251 252 /* Error on TTY ?! */ 253 if (tty_wr < 0) 254 goto error; 255 /* Reduce buffer written, and discard if empty */ 256 skb_pull(skb, tty_wr); 257 if (skb->len == 0) { 258 struct sk_buff *tmp = skb_dequeue(&ser->head); 259 WARN_ON(tmp != skb); 260 if (in_interrupt()) 261 dev_kfree_skb_irq(skb); 262 else 263 kfree_skb(skb); 264 } 265 } 266 /* Send flow off if queue is empty */ 267 if (ser->head.qlen <= SEND_QUEUE_LOW && 268 test_and_clear_bit(CAIF_FLOW_OFF_SENT, &ser->state) && 269 ser->common.flowctrl != NULL) 270 ser->common.flowctrl(ser->dev, ON); 271 clear_bit(CAIF_SENDING, &ser->state); 272 return 0; 273 error: 274 clear_bit(CAIF_SENDING, &ser->state); 275 return tty_wr; 276 } 277 278 static int caif_xmit(struct sk_buff *skb, struct net_device *dev) 279 { 280 struct ser_device *ser; 281 282 BUG_ON(dev == NULL); 283 ser = netdev_priv(dev); 284 285 /* Send flow off once, on high water mark */ 286 if (ser->head.qlen > SEND_QUEUE_HIGH && 287 !test_and_set_bit(CAIF_FLOW_OFF_SENT, &ser->state) && 288 ser->common.flowctrl != NULL) 289 290 ser->common.flowctrl(ser->dev, OFF); 291 292 skb_queue_tail(&ser->head, skb); 293 return handle_tx(ser); 294 } 295 296 297 static void ldisc_tx_wakeup(struct tty_struct *tty) 298 { 299 struct ser_device *ser; 300 301 ser = tty->disc_data; 302 BUG_ON(ser == NULL); 303 WARN_ON(ser->tty != tty); 304 handle_tx(ser); 305 } 306 307 308 static void ser_release(struct work_struct *work) 309 { 310 struct list_head list; 311 struct ser_device *ser, *tmp; 312 313 spin_lock(&ser_lock); 314 list_replace_init(&ser_release_list, &list); 315 spin_unlock(&ser_lock); 316 317 if (!list_empty(&list)) { 318 rtnl_lock(); 319 list_for_each_entry_safe(ser, tmp, &list, node) { 320 dev_close(ser->dev); 321 unregister_netdevice(ser->dev); 322 debugfs_deinit(ser); 323 } 324 rtnl_unlock(); 325 } 326 } 327 328 static DECLARE_WORK(ser_release_work, ser_release); 329 330 static int ldisc_open(struct tty_struct *tty) 331 { 332 struct ser_device *ser; 333 struct net_device *dev; 334 char name[64]; 335 int result; 336 337 /* No write no play */ 338 if (tty->ops->write == NULL) 339 return -EOPNOTSUPP; 340 if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_TTY_CONFIG)) 341 return -EPERM; 342 343 /* release devices to avoid name collision */ 344 ser_release(NULL); 345 346 result = snprintf(name, sizeof(name), "cf%s", tty->name); 347 if (result >= IFNAMSIZ) 348 return -EINVAL; 349 dev = alloc_netdev(sizeof(*ser), name, NET_NAME_UNKNOWN, 350 caifdev_setup); 351 if (!dev) 352 return -ENOMEM; 353 354 ser = netdev_priv(dev); 355 ser->tty = tty_kref_get(tty); 356 ser->dev = dev; 357 debugfs_init(ser, tty); 358 tty->receive_room = N_TTY_BUF_SIZE; 359 tty->disc_data = ser; 360 set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); 361 rtnl_lock(); 362 result = register_netdevice(dev); 363 if (result) { 364 rtnl_unlock(); 365 free_netdev(dev); 366 return -ENODEV; 367 } 368 369 spin_lock(&ser_lock); 370 list_add(&ser->node, &ser_list); 371 spin_unlock(&ser_lock); 372 rtnl_unlock(); 373 netif_stop_queue(dev); 374 update_tty_status(ser); 375 return 0; 376 } 377 378 static void ldisc_close(struct tty_struct *tty) 379 { 380 struct ser_device *ser = tty->disc_data; 381 382 tty_kref_put(ser->tty); 383 384 spin_lock(&ser_lock); 385 list_move(&ser->node, &ser_release_list); 386 spin_unlock(&ser_lock); 387 schedule_work(&ser_release_work); 388 } 389 390 /* The line discipline structure. */ 391 static struct tty_ldisc_ops caif_ldisc = { 392 .owner = THIS_MODULE, 393 .magic = TTY_LDISC_MAGIC, 394 .name = "n_caif", 395 .open = ldisc_open, 396 .close = ldisc_close, 397 .receive_buf = ldisc_receive, 398 .write_wakeup = ldisc_tx_wakeup 399 }; 400 401 static int register_ldisc(void) 402 { 403 int result; 404 405 result = tty_register_ldisc(N_CAIF, &caif_ldisc); 406 if (result < 0) { 407 pr_err("cannot register CAIF ldisc=%d err=%d\n", N_CAIF, 408 result); 409 return result; 410 } 411 return result; 412 } 413 static const struct net_device_ops netdev_ops = { 414 .ndo_open = caif_net_open, 415 .ndo_stop = caif_net_close, 416 .ndo_start_xmit = caif_xmit 417 }; 418 419 static void caifdev_setup(struct net_device *dev) 420 { 421 struct ser_device *serdev = netdev_priv(dev); 422 423 dev->features = 0; 424 dev->netdev_ops = &netdev_ops; 425 dev->type = ARPHRD_CAIF; 426 dev->flags = IFF_POINTOPOINT | IFF_NOARP; 427 dev->mtu = CAIF_MAX_MTU; 428 dev->priv_flags |= IFF_NO_QUEUE; 429 dev->needs_free_netdev = true; 430 skb_queue_head_init(&serdev->head); 431 serdev->common.link_select = CAIF_LINK_LOW_LATENCY; 432 serdev->common.use_frag = true; 433 serdev->common.use_stx = ser_use_stx; 434 serdev->common.use_fcs = ser_use_fcs; 435 serdev->dev = dev; 436 } 437 438 439 static int caif_net_open(struct net_device *dev) 440 { 441 netif_wake_queue(dev); 442 return 0; 443 } 444 445 static int caif_net_close(struct net_device *dev) 446 { 447 netif_stop_queue(dev); 448 return 0; 449 } 450 451 static int __init caif_ser_init(void) 452 { 453 int ret; 454 455 ret = register_ldisc(); 456 debugfsdir = debugfs_create_dir("caif_serial", NULL); 457 return ret; 458 } 459 460 static void __exit caif_ser_exit(void) 461 { 462 spin_lock(&ser_lock); 463 list_splice(&ser_list, &ser_release_list); 464 spin_unlock(&ser_lock); 465 ser_release(NULL); 466 cancel_work_sync(&ser_release_work); 467 tty_unregister_ldisc(N_CAIF); 468 debugfs_remove_recursive(debugfsdir); 469 } 470 471 module_init(caif_ser_init); 472 module_exit(caif_ser_exit); 473