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