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 /*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->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 skb->dev = ser->dev; 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 int ldisc_open(struct tty_struct *tty) 312 { 313 struct ser_device *ser; 314 struct net_device *dev; 315 char name[64]; 316 int result; 317 318 /* No write no play */ 319 if (tty->ops->write == NULL) 320 return -EOPNOTSUPP; 321 if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_TTY_CONFIG)) 322 return -EPERM; 323 324 sprintf(name, "cf%s", tty->name); 325 dev = alloc_netdev(sizeof(*ser), name, caifdev_setup); 326 if (!dev) 327 return -ENOMEM; 328 329 ser = netdev_priv(dev); 330 ser->tty = tty_kref_get(tty); 331 ser->dev = dev; 332 debugfs_init(ser, tty); 333 tty->receive_room = N_TTY_BUF_SIZE; 334 tty->disc_data = ser; 335 set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); 336 rtnl_lock(); 337 result = register_netdevice(dev); 338 if (result) { 339 rtnl_unlock(); 340 free_netdev(dev); 341 return -ENODEV; 342 } 343 344 list_add(&ser->node, &ser_list); 345 rtnl_unlock(); 346 netif_stop_queue(dev); 347 update_tty_status(ser); 348 return 0; 349 } 350 351 static void ldisc_close(struct tty_struct *tty) 352 { 353 struct ser_device *ser = tty->disc_data; 354 /* Remove may be called inside or outside of rtnl_lock */ 355 int islocked = rtnl_is_locked(); 356 357 if (!islocked) 358 rtnl_lock(); 359 /* device is freed automagically by net-sysfs */ 360 dev_close(ser->dev); 361 unregister_netdevice(ser->dev); 362 list_del(&ser->node); 363 debugfs_deinit(ser); 364 tty_kref_put(ser->tty); 365 if (!islocked) 366 rtnl_unlock(); 367 } 368 369 /* The line discipline structure. */ 370 static struct tty_ldisc_ops caif_ldisc = { 371 .owner = THIS_MODULE, 372 .magic = TTY_LDISC_MAGIC, 373 .name = "n_caif", 374 .open = ldisc_open, 375 .close = ldisc_close, 376 .receive_buf = ldisc_receive, 377 .write_wakeup = ldisc_tx_wakeup 378 }; 379 380 static int register_ldisc(void) 381 { 382 int result; 383 384 result = tty_register_ldisc(N_CAIF, &caif_ldisc); 385 if (result < 0) { 386 pr_err("cannot register CAIF ldisc=%d err=%d\n", N_CAIF, 387 result); 388 return result; 389 } 390 return result; 391 } 392 static const struct net_device_ops netdev_ops = { 393 .ndo_open = caif_net_open, 394 .ndo_stop = caif_net_close, 395 .ndo_start_xmit = caif_xmit 396 }; 397 398 static void caifdev_setup(struct net_device *dev) 399 { 400 struct ser_device *serdev = netdev_priv(dev); 401 402 dev->features = 0; 403 dev->netdev_ops = &netdev_ops; 404 dev->type = ARPHRD_CAIF; 405 dev->flags = IFF_POINTOPOINT | IFF_NOARP; 406 dev->mtu = CAIF_MAX_MTU; 407 dev->tx_queue_len = 0; 408 dev->destructor = free_netdev; 409 skb_queue_head_init(&serdev->head); 410 serdev->common.link_select = CAIF_LINK_LOW_LATENCY; 411 serdev->common.use_frag = true; 412 serdev->common.use_stx = ser_use_stx; 413 serdev->common.use_fcs = ser_use_fcs; 414 serdev->dev = dev; 415 } 416 417 418 static int caif_net_open(struct net_device *dev) 419 { 420 netif_wake_queue(dev); 421 return 0; 422 } 423 424 static int caif_net_close(struct net_device *dev) 425 { 426 netif_stop_queue(dev); 427 return 0; 428 } 429 430 static int __init caif_ser_init(void) 431 { 432 int ret; 433 434 ret = register_ldisc(); 435 debugfsdir = debugfs_create_dir("caif_serial", NULL); 436 return ret; 437 } 438 439 static void __exit caif_ser_exit(void) 440 { 441 struct ser_device *ser = NULL; 442 struct list_head *node; 443 struct list_head *_tmp; 444 445 list_for_each_safe(node, _tmp, &ser_list) { 446 ser = list_entry(node, struct ser_device, node); 447 dev_close(ser->dev); 448 unregister_netdevice(ser->dev); 449 list_del(node); 450 } 451 tty_unregister_ldisc(N_CAIF); 452 debugfs_remove_recursive(debugfsdir); 453 } 454 455 module_init(caif_ser_init); 456 module_exit(caif_ser_exit); 457