net/nfc/nci/uart.c

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This source file includes following definitions.
nci_uart_dequeue
nci_uart_queue_empty
nci_uart_tx_wakeup
nci_uart_write_work
nci_uart_set_driver
nci_uart_tty_open
nci_uart_tty_close
nci_uart_tty_wakeup
nci_uart_tty_receive
nci_uart_tty_ioctl
nci_uart_tty_read
nci_uart_tty_write
nci_uart_tty_poll
nci_uart_send
nci_uart_default_recv_buf
nci_uart_default_recv
nci_uart_register
nci_uart_unregister
nci_uart_set_config
nci_uart_init
nci_uart_exit
   1 /*
   2  * Copyright (C) 2015, Marvell International Ltd.
   3  *
   4  * This software file (the "File") is distributed by Marvell International
   5  * Ltd. under the terms of the GNU General Public License Version 2, June 1991
   6  * (the "License").  You may use, redistribute and/or modify this File in
   7  * accordance with the terms and conditions of the License, a copy of which
   8  * is available on the worldwide web at
   9  * http://www.gnu.org/licenses/old-licenses/gpl-2.0.txt.
  10  *
  11  * THE FILE IS DISTRIBUTED AS-IS, WITHOUT WARRANTY OF ANY KIND, AND THE
  12  * IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE
  13  * ARE EXPRESSLY DISCLAIMED.  The License provides additional details about
  14  * this warranty disclaimer.
  15  */
  16 
  17 /* Inspired (hugely) by HCI LDISC implementation in Bluetooth.
  18  *
  19  *  Copyright (C) 2000-2001  Qualcomm Incorporated
  20  *  Copyright (C) 2002-2003  Maxim Krasnyansky <maxk@qualcomm.com>
  21  *  Copyright (C) 2004-2005  Marcel Holtmann <marcel@holtmann.org>
  22  */
  23 
  24 #include <linux/module.h>
  25 
  26 #include <linux/kernel.h>
  27 #include <linux/init.h>
  28 #include <linux/types.h>
  29 #include <linux/fcntl.h>
  30 #include <linux/interrupt.h>
  31 #include <linux/ptrace.h>
  32 #include <linux/poll.h>
  33 
  34 #include <linux/slab.h>
  35 #include <linux/tty.h>
  36 #include <linux/errno.h>
  37 #include <linux/string.h>
  38 #include <linux/signal.h>
  39 #include <linux/ioctl.h>
  40 #include <linux/skbuff.h>
  41 
  42 #include <net/nfc/nci.h>
  43 #include <net/nfc/nci_core.h>
  44 
  45 /* TX states  */
  46 #define NCI_UART_SENDING        1
  47 #define NCI_UART_TX_WAKEUP      2
  48 
  49 static struct nci_uart *nci_uart_drivers[NCI_UART_DRIVER_MAX];
  50 
  51 static inline struct sk_buff *nci_uart_dequeue(struct nci_uart *nu)
  52 {
  53         struct sk_buff *skb = nu->tx_skb;
  54 
  55         if (!skb)
  56                 skb = skb_dequeue(&nu->tx_q);
  57         else
  58                 nu->tx_skb = NULL;
  59 
  60         return skb;
  61 }
  62 
  63 static inline int nci_uart_queue_empty(struct nci_uart *nu)
  64 {
  65         if (nu->tx_skb)
  66                 return 0;
  67 
  68         return skb_queue_empty(&nu->tx_q);
  69 }
  70 
  71 static int nci_uart_tx_wakeup(struct nci_uart *nu)
  72 {
  73         if (test_and_set_bit(NCI_UART_SENDING, &nu->tx_state)) {
  74                 set_bit(NCI_UART_TX_WAKEUP, &nu->tx_state);
  75                 return 0;
  76         }
  77 
  78         schedule_work(&nu->write_work);
  79 
  80         return 0;
  81 }
  82 
  83 static void nci_uart_write_work(struct work_struct *work)
  84 {
  85         struct nci_uart *nu = container_of(work, struct nci_uart, write_work);
  86         struct tty_struct *tty = nu->tty;
  87         struct sk_buff *skb;
  88 
  89 restart:
  90         clear_bit(NCI_UART_TX_WAKEUP, &nu->tx_state);
  91 
  92         if (nu->ops.tx_start)
  93                 nu->ops.tx_start(nu);
  94 
  95         while ((skb = nci_uart_dequeue(nu))) {
  96                 int len;
  97 
  98                 set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
  99                 len = tty->ops->write(tty, skb->data, skb->len);
 100                 skb_pull(skb, len);
 101                 if (skb->len) {
 102                         nu->tx_skb = skb;
 103                         break;
 104                 }
 105                 kfree_skb(skb);
 106         }
 107 
 108         if (test_bit(NCI_UART_TX_WAKEUP, &nu->tx_state))
 109                 goto restart;
 110 
 111         if (nu->ops.tx_done && nci_uart_queue_empty(nu))
 112                 nu->ops.tx_done(nu);
 113 
 114         clear_bit(NCI_UART_SENDING, &nu->tx_state);
 115 }
 116 
 117 static int nci_uart_set_driver(struct tty_struct *tty, unsigned int driver)
 118 {
 119         struct nci_uart *nu = NULL;
 120         int ret;
 121 
 122         if (driver >= NCI_UART_DRIVER_MAX)
 123                 return -EINVAL;
 124 
 125         if (!nci_uart_drivers[driver])
 126                 return -ENOENT;
 127 
 128         nu = kzalloc(sizeof(*nu), GFP_KERNEL);
 129         if (!nu)
 130                 return -ENOMEM;
 131 
 132         memcpy(nu, nci_uart_drivers[driver], sizeof(struct nci_uart));
 133         nu->tty = tty;
 134         tty->disc_data = nu;
 135         skb_queue_head_init(&nu->tx_q);
 136         INIT_WORK(&nu->write_work, nci_uart_write_work);
 137         spin_lock_init(&nu->rx_lock);
 138 
 139         ret = nu->ops.open(nu);
 140         if (ret) {
 141                 tty->disc_data = NULL;
 142                 kfree(nu);
 143         } else if (!try_module_get(nu->owner)) {
 144                 nu->ops.close(nu);
 145                 tty->disc_data = NULL;
 146                 kfree(nu);
 147                 return -ENOENT;
 148         }
 149         return ret;
 150 }
 151 
 152 /* ------ LDISC part ------ */
 153 
 154 /* nci_uart_tty_open
 155  *
 156  *     Called when line discipline changed to NCI_UART.
 157  *
 158  * Arguments:
 159  *     tty    pointer to tty info structure
 160  * Return Value:
 161  *     0 if success, otherwise error code
 162  */
 163 static int nci_uart_tty_open(struct tty_struct *tty)
 164 {
 165         /* Error if the tty has no write op instead of leaving an exploitable
 166          * hole
 167          */
 168         if (!tty->ops->write)
 169                 return -EOPNOTSUPP;
 170 
 171         tty->disc_data = NULL;
 172         tty->receive_room = 65536;
 173 
 174         /* Flush any pending characters in the driver */
 175         tty_driver_flush_buffer(tty);
 176 
 177         return 0;
 178 }
 179 
 180 /* nci_uart_tty_close()
 181  *
 182  *    Called when the line discipline is changed to something
 183  *    else, the tty is closed, or the tty detects a hangup.
 184  */
 185 static void nci_uart_tty_close(struct tty_struct *tty)
 186 {
 187         struct nci_uart *nu = (void *)tty->disc_data;
 188 
 189         /* Detach from the tty */
 190         tty->disc_data = NULL;
 191 
 192         if (!nu)
 193                 return;
 194 
 195         kfree_skb(nu->tx_skb);
 196         kfree_skb(nu->rx_skb);
 197 
 198         skb_queue_purge(&nu->tx_q);
 199 
 200         nu->ops.close(nu);
 201         nu->tty = NULL;
 202         module_put(nu->owner);
 203 
 204         cancel_work_sync(&nu->write_work);
 205 
 206         kfree(nu);
 207 }
 208 
 209 /* nci_uart_tty_wakeup()
 210  *
 211  *    Callback for transmit wakeup. Called when low level
 212  *    device driver can accept more send data.
 213  *
 214  * Arguments:        tty    pointer to associated tty instance data
 215  * Return Value:    None
 216  */
 217 static void nci_uart_tty_wakeup(struct tty_struct *tty)
 218 {
 219         struct nci_uart *nu = (void *)tty->disc_data;
 220 
 221         if (!nu)
 222                 return;
 223 
 224         clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
 225 
 226         if (tty != nu->tty)
 227                 return;
 228 
 229         nci_uart_tx_wakeup(nu);
 230 }
 231 
 232 /* nci_uart_tty_receive()
 233  *
 234  *     Called by tty low level driver when receive data is
 235  *     available.
 236  *
 237  * Arguments:  tty          pointer to tty isntance data
 238  *             data         pointer to received data
 239  *             flags        pointer to flags for data
 240  *             count        count of received data in bytes
 241  *
 242  * Return Value:    None
 243  */
 244 static void nci_uart_tty_receive(struct tty_struct *tty, const u8 *data,
 245                                  char *flags, int count)
 246 {
 247         struct nci_uart *nu = (void *)tty->disc_data;
 248 
 249         if (!nu || tty != nu->tty)
 250                 return;
 251 
 252         spin_lock(&nu->rx_lock);
 253         nu->ops.recv_buf(nu, (void *)data, flags, count);
 254         spin_unlock(&nu->rx_lock);
 255 
 256         tty_unthrottle(tty);
 257 }
 258 
 259 /* nci_uart_tty_ioctl()
 260  *
 261  *    Process IOCTL system call for the tty device.
 262  *
 263  * Arguments:
 264  *
 265  *    tty        pointer to tty instance data
 266  *    file       pointer to open file object for device
 267  *    cmd        IOCTL command code
 268  *    arg        argument for IOCTL call (cmd dependent)
 269  *
 270  * Return Value:    Command dependent
 271  */
 272 static int nci_uart_tty_ioctl(struct tty_struct *tty, struct file *file,
 273                               unsigned int cmd, unsigned long arg)
 274 {
 275         struct nci_uart *nu = (void *)tty->disc_data;
 276         int err = 0;
 277 
 278         switch (cmd) {
 279         case NCIUARTSETDRIVER:
 280                 if (!nu)
 281                         return nci_uart_set_driver(tty, (unsigned int)arg);
 282                 else
 283                         return -EBUSY;
 284                 break;
 285         default:
 286                 err = n_tty_ioctl_helper(tty, file, cmd, arg);
 287                 break;
 288         }
 289 
 290         return err;
 291 }
 292 
 293 /* We don't provide read/write/poll interface for user space. */
 294 static ssize_t nci_uart_tty_read(struct tty_struct *tty, struct file *file,
 295                                  unsigned char __user *buf, size_t nr)
 296 {
 297         return 0;
 298 }
 299 
 300 static ssize_t nci_uart_tty_write(struct tty_struct *tty, struct file *file,
 301                                   const unsigned char *data, size_t count)
 302 {
 303         return 0;
 304 }
 305 
 306 static __poll_t nci_uart_tty_poll(struct tty_struct *tty,
 307                                       struct file *filp, poll_table *wait)
 308 {
 309         return 0;
 310 }
 311 
 312 static int nci_uart_send(struct nci_uart *nu, struct sk_buff *skb)
 313 {
 314         /* Queue TX packet */
 315         skb_queue_tail(&nu->tx_q, skb);
 316 
 317         /* Try to start TX (if possible) */
 318         nci_uart_tx_wakeup(nu);
 319 
 320         return 0;
 321 }
 322 
 323 /* -- Default recv_buf handler --
 324  *
 325  * This handler supposes that NCI frames are sent over UART link without any
 326  * framing. It reads NCI header, retrieve the packet size and once all packet
 327  * bytes are received it passes it to nci_uart driver for processing.
 328  */
 329 static int nci_uart_default_recv_buf(struct nci_uart *nu, const u8 *data,
 330                                      char *flags, int count)
 331 {
 332         int chunk_len;
 333 
 334         if (!nu->ndev) {
 335                 nfc_err(nu->tty->dev,
 336                         "receive data from tty but no NCI dev is attached yet, drop buffer\n");
 337                 return 0;
 338         }
 339 
 340         /* Decode all incoming data in packets
 341          * and enqueue then for processing.
 342          */
 343         while (count > 0) {
 344                 /* If this is the first data of a packet, allocate a buffer */
 345                 if (!nu->rx_skb) {
 346                         nu->rx_packet_len = -1;
 347                         nu->rx_skb = nci_skb_alloc(nu->ndev,
 348                                                    NCI_MAX_PACKET_SIZE,
 349                                                    GFP_ATOMIC);
 350                         if (!nu->rx_skb)
 351                                 return -ENOMEM;
 352                 }
 353 
 354                 /* Eat byte after byte till full packet header is received */
 355                 if (nu->rx_skb->len < NCI_CTRL_HDR_SIZE) {
 356                         skb_put_u8(nu->rx_skb, *data++);
 357                         --count;
 358                         continue;
 359                 }
 360 
 361                 /* Header was received but packet len was not read */
 362                 if (nu->rx_packet_len < 0)
 363                         nu->rx_packet_len = NCI_CTRL_HDR_SIZE +
 364                                 nci_plen(nu->rx_skb->data);
 365 
 366                 /* Compute how many bytes are missing and how many bytes can
 367                  * be consumed.
 368                  */
 369                 chunk_len = nu->rx_packet_len - nu->rx_skb->len;
 370                 if (count < chunk_len)
 371                         chunk_len = count;
 372                 skb_put_data(nu->rx_skb, data, chunk_len);
 373                 data += chunk_len;
 374                 count -= chunk_len;
 375 
 376                 /* Chcek if packet is fully received */
 377                 if (nu->rx_packet_len == nu->rx_skb->len) {
 378                         /* Pass RX packet to driver */
 379                         if (nu->ops.recv(nu, nu->rx_skb) != 0)
 380                                 nfc_err(nu->tty->dev, "corrupted RX packet\n");
 381                         /* Next packet will be a new one */
 382                         nu->rx_skb = NULL;
 383                 }
 384         }
 385 
 386         return 0;
 387 }
 388 
 389 /* -- Default recv handler -- */
 390 static int nci_uart_default_recv(struct nci_uart *nu, struct sk_buff *skb)
 391 {
 392         return nci_recv_frame(nu->ndev, skb);
 393 }
 394 
 395 int nci_uart_register(struct nci_uart *nu)
 396 {
 397         if (!nu || !nu->ops.open ||
 398             !nu->ops.recv || !nu->ops.close)
 399                 return -EINVAL;
 400 
 401         /* Set the send callback */
 402         nu->ops.send = nci_uart_send;
 403 
 404         /* Install default handlers if not overridden */
 405         if (!nu->ops.recv_buf)
 406                 nu->ops.recv_buf = nci_uart_default_recv_buf;
 407         if (!nu->ops.recv)
 408                 nu->ops.recv = nci_uart_default_recv;
 409 
 410         /* Add this driver in the driver list */
 411         if (nci_uart_drivers[nu->driver]) {
 412                 pr_err("driver %d is already registered\n", nu->driver);
 413                 return -EBUSY;
 414         }
 415         nci_uart_drivers[nu->driver] = nu;
 416 
 417         pr_info("NCI uart driver '%s [%d]' registered\n", nu->name, nu->driver);
 418 
 419         return 0;
 420 }
 421 EXPORT_SYMBOL_GPL(nci_uart_register);
 422 
 423 void nci_uart_unregister(struct nci_uart *nu)
 424 {
 425         pr_info("NCI uart driver '%s [%d]' unregistered\n", nu->name,
 426                 nu->driver);
 427 
 428         /* Remove this driver from the driver list */
 429         nci_uart_drivers[nu->driver] = NULL;
 430 }
 431 EXPORT_SYMBOL_GPL(nci_uart_unregister);
 432 
 433 void nci_uart_set_config(struct nci_uart *nu, int baudrate, int flow_ctrl)
 434 {
 435         struct ktermios new_termios;
 436 
 437         if (!nu->tty)
 438                 return;
 439 
 440         down_read(&nu->tty->termios_rwsem);
 441         new_termios = nu->tty->termios;
 442         up_read(&nu->tty->termios_rwsem);
 443         tty_termios_encode_baud_rate(&new_termios, baudrate, baudrate);
 444 
 445         if (flow_ctrl)
 446                 new_termios.c_cflag |= CRTSCTS;
 447         else
 448                 new_termios.c_cflag &= ~CRTSCTS;
 449 
 450         tty_set_termios(nu->tty, &new_termios);
 451 }
 452 EXPORT_SYMBOL_GPL(nci_uart_set_config);
 453 
 454 static struct tty_ldisc_ops nci_uart_ldisc = {
 455         .magic          = TTY_LDISC_MAGIC,
 456         .owner          = THIS_MODULE,
 457         .name           = "n_nci",
 458         .open           = nci_uart_tty_open,
 459         .close          = nci_uart_tty_close,
 460         .read           = nci_uart_tty_read,
 461         .write          = nci_uart_tty_write,
 462         .poll           = nci_uart_tty_poll,
 463         .receive_buf    = nci_uart_tty_receive,
 464         .write_wakeup   = nci_uart_tty_wakeup,
 465         .ioctl          = nci_uart_tty_ioctl,
 466         .compat_ioctl   = nci_uart_tty_ioctl,
 467 };
 468 
 469 static int __init nci_uart_init(void)
 470 {
 471         memset(nci_uart_drivers, 0, sizeof(nci_uart_drivers));
 472         return tty_register_ldisc(N_NCI, &nci_uart_ldisc);
 473 }
 474 
 475 static void __exit nci_uart_exit(void)
 476 {
 477         tty_unregister_ldisc(N_NCI);
 478 }
 479 
 480 module_init(nci_uart_init);
 481 module_exit(nci_uart_exit);
 482 
 483 MODULE_AUTHOR("Marvell International Ltd.");
 484 MODULE_DESCRIPTION("NFC NCI UART driver");
 485 MODULE_LICENSE("GPL");
 486 MODULE_ALIAS_LDISC(N_NCI);
/* [<][>][^][v][top][bottom][index][help] */
root/net/nfc/nci/uart.c

DEFINITIONS
