[ARM] mmp2: add support for board IRQs
[linux-2.6.git] / drivers / char / n_hdlc.c
1 /* generic HDLC line discipline for Linux
2  *
3  * Written by Paul Fulghum paulkf@microgate.com
4  * for Microgate Corporation
5  *
6  * Microgate and SyncLink are registered trademarks of Microgate Corporation
7  *
8  * Adapted from ppp.c, written by Michael Callahan <callahan@maths.ox.ac.uk>,
9  *      Al Longyear <longyear@netcom.com>,
10  *      Paul Mackerras <Paul.Mackerras@cs.anu.edu.au>
11  *
12  * Original release 01/11/99
13  *
14  * This code is released under the GNU General Public License (GPL)
15  *
16  * This module implements the tty line discipline N_HDLC for use with
17  * tty device drivers that support bit-synchronous HDLC communications.
18  *
19  * All HDLC data is frame oriented which means:
20  *
21  * 1. tty write calls represent one complete transmit frame of data
22  *    The device driver should accept the complete frame or none of 
23  *    the frame (busy) in the write method. Each write call should have
24  *    a byte count in the range of 2-65535 bytes (2 is min HDLC frame
25  *    with 1 addr byte and 1 ctrl byte). The max byte count of 65535
26  *    should include any crc bytes required. For example, when using
27  *    CCITT CRC32, 4 crc bytes are required, so the maximum size frame
28  *    the application may transmit is limited to 65531 bytes. For CCITT
29  *    CRC16, the maximum application frame size would be 65533.
30  *
31  *
32  * 2. receive callbacks from the device driver represents
33  *    one received frame. The device driver should bypass
34  *    the tty flip buffer and call the line discipline receive
35  *    callback directly to avoid fragmenting or concatenating
36  *    multiple frames into a single receive callback.
37  *
38  *    The HDLC line discipline queues the receive frames in separate
39  *    buffers so complete receive frames can be returned by the
40  *    tty read calls.
41  *
42  * 3. tty read calls returns an entire frame of data or nothing.
43  *    
44  * 4. all send and receive data is considered raw. No processing
45  *    or translation is performed by the line discipline, regardless
46  *    of the tty flags
47  *
48  * 5. When line discipline is queried for the amount of receive
49  *    data available (FIOC), 0 is returned if no data available,
50  *    otherwise the count of the next available frame is returned.
51  *    (instead of the sum of all received frame counts).
52  *
53  * These conventions allow the standard tty programming interface
54  * to be used for synchronous HDLC applications when used with
55  * this line discipline (or another line discipline that is frame
56  * oriented such as N_PPP).
57  *
58  * The SyncLink driver (synclink.c) implements both asynchronous
59  * (using standard line discipline N_TTY) and synchronous HDLC
60  * (using N_HDLC) communications, with the latter using the above
61  * conventions.
62  *
63  * This implementation is very basic and does not maintain
64  * any statistics. The main point is to enforce the raw data
65  * and frame orientation of HDLC communications.
66  *
67  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
68  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
69  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
70  * DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
71  * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
72  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
73  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
74  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
75  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
76  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
77  * OF THE POSSIBILITY OF SUCH DAMAGE.
78  */
79
80 #define HDLC_MAGIC 0x239e
81
82 #include <linux/module.h>
83 #include <linux/init.h>
84 #include <linux/kernel.h>
85 #include <linux/sched.h>
86 #include <linux/types.h>
87 #include <linux/fcntl.h>
88 #include <linux/interrupt.h>
89 #include <linux/ptrace.h>
90
91 #undef VERSION
92 #define VERSION(major,minor,patch) (((((major)<<8)+(minor))<<8)+(patch))
93
94 #include <linux/poll.h>
95 #include <linux/in.h>
96 #include <linux/ioctl.h>
97 #include <linux/slab.h>
98 #include <linux/tty.h>
99 #include <linux/errno.h>
100 #include <linux/smp_lock.h>
101 #include <linux/string.h>       /* used in new tty drivers */
102 #include <linux/signal.h>       /* used in new tty drivers */
103 #include <linux/if.h>
104 #include <linux/bitops.h>
105
106 #include <asm/system.h>
107 #include <asm/termios.h>
108 #include <asm/uaccess.h>
109
110 /*
111  * Buffers for individual HDLC frames
112  */
113 #define MAX_HDLC_FRAME_SIZE 65535 
114 #define DEFAULT_RX_BUF_COUNT 10
115 #define MAX_RX_BUF_COUNT 60
116 #define DEFAULT_TX_BUF_COUNT 3
117
118 struct n_hdlc_buf {
119         struct n_hdlc_buf *link;
120         int               count;
121         char              buf[1];
122 };
123
124 #define N_HDLC_BUF_SIZE (sizeof(struct n_hdlc_buf) + maxframe)
125
126 struct n_hdlc_buf_list {
127         struct n_hdlc_buf *head;
128         struct n_hdlc_buf *tail;
129         int               count;
130         spinlock_t        spinlock;
131 };
132
133 /**
134  * struct n_hdlc - per device instance data structure
135  * @magic - magic value for structure
136  * @flags - miscellaneous control flags
137  * @tty - ptr to TTY structure
138  * @backup_tty - TTY to use if tty gets closed
139  * @tbusy - reentrancy flag for tx wakeup code
140  * @woke_up - FIXME: describe this field
141  * @tbuf - currently transmitting tx buffer
142  * @tx_buf_list - list of pending transmit frame buffers
143  * @rx_buf_list - list of received frame buffers
144  * @tx_free_buf_list - list unused transmit frame buffers
145  * @rx_free_buf_list - list unused received frame buffers
146  */
147 struct n_hdlc {
148         int                     magic;
149         __u32                   flags;
150         struct tty_struct       *tty;
151         struct tty_struct       *backup_tty;
152         int                     tbusy;
153         int                     woke_up;
154         struct n_hdlc_buf       *tbuf;
155         struct n_hdlc_buf_list  tx_buf_list;
156         struct n_hdlc_buf_list  rx_buf_list;
157         struct n_hdlc_buf_list  tx_free_buf_list;
158         struct n_hdlc_buf_list  rx_free_buf_list;
159 };
160
161 /*
162  * HDLC buffer list manipulation functions
163  */
164 static void n_hdlc_buf_list_init(struct n_hdlc_buf_list *list);
165 static void n_hdlc_buf_put(struct n_hdlc_buf_list *list,
166                            struct n_hdlc_buf *buf);
167 static struct n_hdlc_buf *n_hdlc_buf_get(struct n_hdlc_buf_list *list);
168
169 /* Local functions */
170
171 static struct n_hdlc *n_hdlc_alloc (void);
172
173 /* debug level can be set by insmod for debugging purposes */
174 #define DEBUG_LEVEL_INFO        1
175 static int debuglevel;
176
177 /* max frame size for memory allocations */
178 static int maxframe = 4096;
179
180 /* TTY callbacks */
181
182 static ssize_t n_hdlc_tty_read(struct tty_struct *tty, struct file *file,
183                            __u8 __user *buf, size_t nr);
184 static ssize_t n_hdlc_tty_write(struct tty_struct *tty, struct file *file,
185                             const unsigned char *buf, size_t nr);
186 static int n_hdlc_tty_ioctl(struct tty_struct *tty, struct file *file,
187                             unsigned int cmd, unsigned long arg);
188 static unsigned int n_hdlc_tty_poll(struct tty_struct *tty, struct file *filp,
189                                     poll_table *wait);
190 static int n_hdlc_tty_open(struct tty_struct *tty);
191 static void n_hdlc_tty_close(struct tty_struct *tty);
192 static void n_hdlc_tty_receive(struct tty_struct *tty, const __u8 *cp,
193                                char *fp, int count);
194 static void n_hdlc_tty_wakeup(struct tty_struct *tty);
195
196 #define bset(p,b)       ((p)[(b) >> 5] |= (1 << ((b) & 0x1f)))
197
198 #define tty2n_hdlc(tty) ((struct n_hdlc *) ((tty)->disc_data))
199 #define n_hdlc2tty(n_hdlc)      ((n_hdlc)->tty)
200
201 static void flush_rx_queue(struct tty_struct *tty)
202 {
203         struct n_hdlc *n_hdlc = tty2n_hdlc(tty);
204         struct n_hdlc_buf *buf;
205
206         while ((buf = n_hdlc_buf_get(&n_hdlc->rx_buf_list)))
207                 n_hdlc_buf_put(&n_hdlc->rx_free_buf_list, buf);
208 }
209
210 static void flush_tx_queue(struct tty_struct *tty)
211 {
212         struct n_hdlc *n_hdlc = tty2n_hdlc(tty);
213         struct n_hdlc_buf *buf;
214         unsigned long flags;
215
216         while ((buf = n_hdlc_buf_get(&n_hdlc->tx_buf_list)))
217                 n_hdlc_buf_put(&n_hdlc->tx_free_buf_list, buf);
218         spin_lock_irqsave(&n_hdlc->tx_buf_list.spinlock, flags);
219         if (n_hdlc->tbuf) {
220                 n_hdlc_buf_put(&n_hdlc->tx_free_buf_list, n_hdlc->tbuf);
221                 n_hdlc->tbuf = NULL;
222         }
223         spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags);
224 }
225
226 static struct tty_ldisc_ops n_hdlc_ldisc = {
227         .owner          = THIS_MODULE,
228         .magic          = TTY_LDISC_MAGIC,
229         .name           = "hdlc",
230         .open           = n_hdlc_tty_open,
231         .close          = n_hdlc_tty_close,
232         .read           = n_hdlc_tty_read,
233         .write          = n_hdlc_tty_write,
234         .ioctl          = n_hdlc_tty_ioctl,
235         .poll           = n_hdlc_tty_poll,
236         .receive_buf    = n_hdlc_tty_receive,
237         .write_wakeup   = n_hdlc_tty_wakeup,
238         .flush_buffer   = flush_rx_queue,
239 };
240
241 /**
242  * n_hdlc_release - release an n_hdlc per device line discipline info structure
243  * @n_hdlc - per device line discipline info structure
244  */
245 static void n_hdlc_release(struct n_hdlc *n_hdlc)
246 {
247         struct tty_struct *tty = n_hdlc2tty (n_hdlc);
248         struct n_hdlc_buf *buf;
249         
250         if (debuglevel >= DEBUG_LEVEL_INFO)     
251                 printk("%s(%d)n_hdlc_release() called\n",__FILE__,__LINE__);
252                 
253         /* Ensure that the n_hdlcd process is not hanging on select()/poll() */
254         wake_up_interruptible (&tty->read_wait);
255         wake_up_interruptible (&tty->write_wait);
256
257         if (tty->disc_data == n_hdlc)
258                 tty->disc_data = NULL;  /* Break the tty->n_hdlc link */
259
260         /* Release transmit and receive buffers */
261         for(;;) {
262                 buf = n_hdlc_buf_get(&n_hdlc->rx_free_buf_list);
263                 if (buf) {
264                         kfree(buf);
265                 } else
266                         break;
267         }
268         for(;;) {
269                 buf = n_hdlc_buf_get(&n_hdlc->tx_free_buf_list);
270                 if (buf) {
271                         kfree(buf);
272                 } else
273                         break;
274         }
275         for(;;) {
276                 buf = n_hdlc_buf_get(&n_hdlc->rx_buf_list);
277                 if (buf) {
278                         kfree(buf);
279                 } else
280                         break;
281         }
282         for(;;) {
283                 buf = n_hdlc_buf_get(&n_hdlc->tx_buf_list);
284                 if (buf) {
285                         kfree(buf);
286                 } else
287                         break;
288         }
289         kfree(n_hdlc->tbuf);
290         kfree(n_hdlc);
291         
292 }       /* end of n_hdlc_release() */
293
294 /**
295  * n_hdlc_tty_close - line discipline close
296  * @tty - pointer to tty info structure
297  *
298  * Called when the line discipline is changed to something
299  * else, the tty is closed, or the tty detects a hangup.
300  */
301 static void n_hdlc_tty_close(struct tty_struct *tty)
302 {
303         struct n_hdlc *n_hdlc = tty2n_hdlc (tty);
304
305         if (debuglevel >= DEBUG_LEVEL_INFO)     
306                 printk("%s(%d)n_hdlc_tty_close() called\n",__FILE__,__LINE__);
307                 
308         if (n_hdlc != NULL) {
309                 if (n_hdlc->magic != HDLC_MAGIC) {
310                         printk (KERN_WARNING"n_hdlc: trying to close unopened tty!\n");
311                         return;
312                 }
313 #if defined(TTY_NO_WRITE_SPLIT)
314                 clear_bit(TTY_NO_WRITE_SPLIT,&tty->flags);
315 #endif
316                 tty->disc_data = NULL;
317                 if (tty == n_hdlc->backup_tty)
318                         n_hdlc->backup_tty = NULL;
319                 if (tty != n_hdlc->tty)
320                         return;
321                 if (n_hdlc->backup_tty) {
322                         n_hdlc->tty = n_hdlc->backup_tty;
323                 } else {
324                         n_hdlc_release (n_hdlc);
325                 }
326         }
327         
328         if (debuglevel >= DEBUG_LEVEL_INFO)     
329                 printk("%s(%d)n_hdlc_tty_close() success\n",__FILE__,__LINE__);
330                 
331 }       /* end of n_hdlc_tty_close() */
332
333 /**
334  * n_hdlc_tty_open - called when line discipline changed to n_hdlc
335  * @tty - pointer to tty info structure
336  *
337  * Returns 0 if success, otherwise error code
338  */
339 static int n_hdlc_tty_open (struct tty_struct *tty)
340 {
341         struct n_hdlc *n_hdlc = tty2n_hdlc (tty);
342
343         if (debuglevel >= DEBUG_LEVEL_INFO)     
344                 printk("%s(%d)n_hdlc_tty_open() called (device=%s)\n",
345                 __FILE__,__LINE__,
346                 tty->name);
347                 
348         /* There should not be an existing table for this slot. */
349         if (n_hdlc) {
350                 printk (KERN_ERR"n_hdlc_tty_open:tty already associated!\n" );
351                 return -EEXIST;
352         }
353         
354         n_hdlc = n_hdlc_alloc();
355         if (!n_hdlc) {
356                 printk (KERN_ERR "n_hdlc_alloc failed\n");
357                 return -ENFILE;
358         }
359                 
360         tty->disc_data = n_hdlc;
361         n_hdlc->tty    = tty;
362         tty->receive_room = 65536;
363         
364 #if defined(TTY_NO_WRITE_SPLIT)
365         /* change tty_io write() to not split large writes into 8K chunks */
366         set_bit(TTY_NO_WRITE_SPLIT,&tty->flags);
367 #endif
368         
369         /* flush receive data from driver */
370         tty_driver_flush_buffer(tty);
371                 
372         if (debuglevel >= DEBUG_LEVEL_INFO)     
373                 printk("%s(%d)n_hdlc_tty_open() success\n",__FILE__,__LINE__);
374                 
375         return 0;
376         
377 }       /* end of n_tty_hdlc_open() */
378
379 /**
380  * n_hdlc_send_frames - send frames on pending send buffer list
381  * @n_hdlc - pointer to ldisc instance data
382  * @tty - pointer to tty instance data
383  *
384  * Send frames on pending send buffer list until the driver does not accept a
385  * frame (busy) this function is called after adding a frame to the send buffer
386  * list and by the tty wakeup callback.
387  */
388 static void n_hdlc_send_frames(struct n_hdlc *n_hdlc, struct tty_struct *tty)
389 {
390         register int actual;
391         unsigned long flags;
392         struct n_hdlc_buf *tbuf;
393
394         if (debuglevel >= DEBUG_LEVEL_INFO)     
395                 printk("%s(%d)n_hdlc_send_frames() called\n",__FILE__,__LINE__);
396  check_again:
397                 
398         spin_lock_irqsave(&n_hdlc->tx_buf_list.spinlock, flags);
399         if (n_hdlc->tbusy) {
400                 n_hdlc->woke_up = 1;
401                 spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags);
402                 return;
403         }
404         n_hdlc->tbusy = 1;
405         n_hdlc->woke_up = 0;
406         spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags);
407
408         /* get current transmit buffer or get new transmit */
409         /* buffer from list of pending transmit buffers */
410                 
411         tbuf = n_hdlc->tbuf;
412         if (!tbuf)
413                 tbuf = n_hdlc_buf_get(&n_hdlc->tx_buf_list);
414                 
415         while (tbuf) {
416                 if (debuglevel >= DEBUG_LEVEL_INFO)     
417                         printk("%s(%d)sending frame %p, count=%d\n",
418                                 __FILE__,__LINE__,tbuf,tbuf->count);
419                         
420                 /* Send the next block of data to device */
421                 tty->flags |= (1 << TTY_DO_WRITE_WAKEUP);
422                 actual = tty->ops->write(tty, tbuf->buf, tbuf->count);
423
424                 /* rollback was possible and has been done */
425                 if (actual == -ERESTARTSYS) {
426                         n_hdlc->tbuf = tbuf;
427                         break;
428                 }
429                 /* if transmit error, throw frame away by */
430                 /* pretending it was accepted by driver */
431                 if (actual < 0)
432                         actual = tbuf->count;
433                 
434                 if (actual == tbuf->count) {
435                         if (debuglevel >= DEBUG_LEVEL_INFO)     
436                                 printk("%s(%d)frame %p completed\n",
437                                         __FILE__,__LINE__,tbuf);
438                                         
439                         /* free current transmit buffer */
440                         n_hdlc_buf_put(&n_hdlc->tx_free_buf_list, tbuf);
441                         
442                         /* this tx buffer is done */
443                         n_hdlc->tbuf = NULL;
444                         
445                         /* wait up sleeping writers */
446                         wake_up_interruptible(&tty->write_wait);
447         
448                         /* get next pending transmit buffer */
449                         tbuf = n_hdlc_buf_get(&n_hdlc->tx_buf_list);
450                 } else {
451                         if (debuglevel >= DEBUG_LEVEL_INFO)     
452                                 printk("%s(%d)frame %p pending\n",
453                                         __FILE__,__LINE__,tbuf);
454                                         
455                         /* buffer not accepted by driver */
456                         /* set this buffer as pending buffer */
457                         n_hdlc->tbuf = tbuf;
458                         break;
459                 }
460         }
461         
462         if (!tbuf)
463                 tty->flags  &= ~(1 << TTY_DO_WRITE_WAKEUP);
464         
465         /* Clear the re-entry flag */
466         spin_lock_irqsave(&n_hdlc->tx_buf_list.spinlock, flags);
467         n_hdlc->tbusy = 0;
468         spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags); 
469         
470         if (n_hdlc->woke_up)
471           goto check_again;
472
473         if (debuglevel >= DEBUG_LEVEL_INFO)     
474                 printk("%s(%d)n_hdlc_send_frames() exit\n",__FILE__,__LINE__);
475                 
476 }       /* end of n_hdlc_send_frames() */
477
478 /**
479  * n_hdlc_tty_wakeup - Callback for transmit wakeup
480  * @tty - pointer to associated tty instance data
481  *
482  * Called when low level device driver can accept more send data.
483  */
484 static void n_hdlc_tty_wakeup(struct tty_struct *tty)
485 {
486         struct n_hdlc *n_hdlc = tty2n_hdlc(tty);
487
488         if (debuglevel >= DEBUG_LEVEL_INFO)     
489                 printk("%s(%d)n_hdlc_tty_wakeup() called\n",__FILE__,__LINE__);
490                 
491         if (!n_hdlc)
492                 return;
493
494         if (tty != n_hdlc->tty) {
495                 tty->flags &= ~(1 << TTY_DO_WRITE_WAKEUP);
496                 return;
497         }
498
499         n_hdlc_send_frames (n_hdlc, tty);
500                 
501 }       /* end of n_hdlc_tty_wakeup() */
502
503 /**
504  * n_hdlc_tty_receive - Called by tty driver when receive data is available
505  * @tty - pointer to tty instance data
506  * @data - pointer to received data
507  * @flags - pointer to flags for data
508  * @count - count of received data in bytes
509  *
510  * Called by tty low level driver when receive data is available. Data is
511  * interpreted as one HDLC frame.
512  */
513 static void n_hdlc_tty_receive(struct tty_struct *tty, const __u8 *data,
514                                char *flags, int count)
515 {
516         register struct n_hdlc *n_hdlc = tty2n_hdlc (tty);
517         register struct n_hdlc_buf *buf;
518
519         if (debuglevel >= DEBUG_LEVEL_INFO)     
520                 printk("%s(%d)n_hdlc_tty_receive() called count=%d\n",
521                         __FILE__,__LINE__, count);
522                 
523         /* This can happen if stuff comes in on the backup tty */
524         if (!n_hdlc || tty != n_hdlc->tty)
525                 return;
526                 
527         /* verify line is using HDLC discipline */
528         if (n_hdlc->magic != HDLC_MAGIC) {
529                 printk("%s(%d) line not using HDLC discipline\n",
530                         __FILE__,__LINE__);
531                 return;
532         }
533         
534         if ( count>maxframe ) {
535                 if (debuglevel >= DEBUG_LEVEL_INFO)     
536                         printk("%s(%d) rx count>maxframesize, data discarded\n",
537                                __FILE__,__LINE__);
538                 return;
539         }
540
541         /* get a free HDLC buffer */    
542         buf = n_hdlc_buf_get(&n_hdlc->rx_free_buf_list);
543         if (!buf) {
544                 /* no buffers in free list, attempt to allocate another rx buffer */
545                 /* unless the maximum count has been reached */
546                 if (n_hdlc->rx_buf_list.count < MAX_RX_BUF_COUNT)
547                         buf = kmalloc(N_HDLC_BUF_SIZE, GFP_ATOMIC);
548         }
549         
550         if (!buf) {
551                 if (debuglevel >= DEBUG_LEVEL_INFO)     
552                         printk("%s(%d) no more rx buffers, data discarded\n",
553                                __FILE__,__LINE__);
554                 return;
555         }
556                 
557         /* copy received data to HDLC buffer */
558         memcpy(buf->buf,data,count);
559         buf->count=count;
560
561         /* add HDLC buffer to list of received frames */
562         n_hdlc_buf_put(&n_hdlc->rx_buf_list, buf);
563         
564         /* wake up any blocked reads and perform async signalling */
565         wake_up_interruptible (&tty->read_wait);
566         if (n_hdlc->tty->fasync != NULL)
567                 kill_fasync (&n_hdlc->tty->fasync, SIGIO, POLL_IN);
568
569 }       /* end of n_hdlc_tty_receive() */
570
571 /**
572  * n_hdlc_tty_read - Called to retrieve one frame of data (if available)
573  * @tty - pointer to tty instance data
574  * @file - pointer to open file object
575  * @buf - pointer to returned data buffer
576  * @nr - size of returned data buffer
577  *      
578  * Returns the number of bytes returned or error code.
579  */
580 static ssize_t n_hdlc_tty_read(struct tty_struct *tty, struct file *file,
581                            __u8 __user *buf, size_t nr)
582 {
583         struct n_hdlc *n_hdlc = tty2n_hdlc(tty);
584         int ret;
585         struct n_hdlc_buf *rbuf;
586
587         if (debuglevel >= DEBUG_LEVEL_INFO)     
588                 printk("%s(%d)n_hdlc_tty_read() called\n",__FILE__,__LINE__);
589                 
590         /* Validate the pointers */
591         if (!n_hdlc)
592                 return -EIO;
593
594         /* verify user access to buffer */
595         if (!access_ok(VERIFY_WRITE, buf, nr)) {
596                 printk(KERN_WARNING "%s(%d) n_hdlc_tty_read() can't verify user "
597                 "buffer\n", __FILE__, __LINE__);
598                 return -EFAULT;
599         }
600
601         lock_kernel();
602
603         for (;;) {
604                 if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) {
605                         unlock_kernel();
606                         return -EIO;
607                 }
608
609                 n_hdlc = tty2n_hdlc (tty);
610                 if (!n_hdlc || n_hdlc->magic != HDLC_MAGIC ||
611                          tty != n_hdlc->tty) {
612                         unlock_kernel();
613                         return 0;
614                 }
615
616                 rbuf = n_hdlc_buf_get(&n_hdlc->rx_buf_list);
617                 if (rbuf)
618                         break;
619                         
620                 /* no data */
621                 if (file->f_flags & O_NONBLOCK) {
622                         unlock_kernel();
623                         return -EAGAIN;
624                 }
625                         
626                 interruptible_sleep_on (&tty->read_wait);
627                 if (signal_pending(current)) {
628                         unlock_kernel();
629                         return -EINTR;
630                 }
631         }
632                 
633         if (rbuf->count > nr)
634                 /* frame too large for caller's buffer (discard frame) */
635                 ret = -EOVERFLOW;
636         else {
637                 /* Copy the data to the caller's buffer */
638                 if (copy_to_user(buf, rbuf->buf, rbuf->count))
639                         ret = -EFAULT;
640                 else
641                         ret = rbuf->count;
642         }
643         
644         /* return HDLC buffer to free list unless the free list */
645         /* count has exceeded the default value, in which case the */
646         /* buffer is freed back to the OS to conserve memory */
647         if (n_hdlc->rx_free_buf_list.count > DEFAULT_RX_BUF_COUNT)
648                 kfree(rbuf);
649         else    
650                 n_hdlc_buf_put(&n_hdlc->rx_free_buf_list,rbuf);
651         unlock_kernel();
652         return ret;
653         
654 }       /* end of n_hdlc_tty_read() */
655
656 /**
657  * n_hdlc_tty_write - write a single frame of data to device
658  * @tty - pointer to associated tty device instance data
659  * @file - pointer to file object data
660  * @data - pointer to transmit data (one frame)
661  * @count - size of transmit frame in bytes
662  *              
663  * Returns the number of bytes written (or error code).
664  */
665 static ssize_t n_hdlc_tty_write(struct tty_struct *tty, struct file *file,
666                             const unsigned char *data, size_t count)
667 {
668         struct n_hdlc *n_hdlc = tty2n_hdlc (tty);
669         int error = 0;
670         DECLARE_WAITQUEUE(wait, current);
671         struct n_hdlc_buf *tbuf;
672
673         if (debuglevel >= DEBUG_LEVEL_INFO)     
674                 printk("%s(%d)n_hdlc_tty_write() called count=%Zd\n",
675                         __FILE__,__LINE__,count);
676                 
677         /* Verify pointers */
678         if (!n_hdlc)
679                 return -EIO;
680
681         if (n_hdlc->magic != HDLC_MAGIC)
682                 return -EIO;
683
684         /* verify frame size */
685         if (count > maxframe ) {
686                 if (debuglevel & DEBUG_LEVEL_INFO)
687                         printk (KERN_WARNING
688                                 "n_hdlc_tty_write: truncating user packet "
689                                 "from %lu to %d\n", (unsigned long) count,
690                                 maxframe );
691                 count = maxframe;
692         }
693         
694         lock_kernel();
695
696         add_wait_queue(&tty->write_wait, &wait);
697         set_current_state(TASK_INTERRUPTIBLE);
698         
699         /* Allocate transmit buffer */
700         /* sleep until transmit buffer available */             
701         while (!(tbuf = n_hdlc_buf_get(&n_hdlc->tx_free_buf_list))) {
702                 if (file->f_flags & O_NONBLOCK) {
703                         error = -EAGAIN;
704                         break;
705                 }
706                 schedule();
707                         
708                 n_hdlc = tty2n_hdlc (tty);
709                 if (!n_hdlc || n_hdlc->magic != HDLC_MAGIC || 
710                     tty != n_hdlc->tty) {
711                         printk("n_hdlc_tty_write: %p invalid after wait!\n", n_hdlc);
712                         error = -EIO;
713                         break;
714                 }
715                         
716                 if (signal_pending(current)) {
717                         error = -EINTR;
718                         break;
719                 }
720         }
721
722         set_current_state(TASK_RUNNING);
723         remove_wait_queue(&tty->write_wait, &wait);
724
725         if (!error) {           
726                 /* Retrieve the user's buffer */
727                 memcpy(tbuf->buf, data, count);
728
729                 /* Send the data */
730                 tbuf->count = error = count;
731                 n_hdlc_buf_put(&n_hdlc->tx_buf_list,tbuf);
732                 n_hdlc_send_frames(n_hdlc,tty);
733         }
734         unlock_kernel();
735         return error;
736         
737 }       /* end of n_hdlc_tty_write() */
738
739 /**
740  * n_hdlc_tty_ioctl - process IOCTL system call for the tty device.
741  * @tty - pointer to tty instance data
742  * @file - pointer to open file object for device
743  * @cmd - IOCTL command code
744  * @arg - argument for IOCTL call (cmd dependent)
745  *
746  * Returns command dependent result.
747  */
748 static int n_hdlc_tty_ioctl(struct tty_struct *tty, struct file *file,
749                             unsigned int cmd, unsigned long arg)
750 {
751         struct n_hdlc *n_hdlc = tty2n_hdlc (tty);
752         int error = 0;
753         int count;
754         unsigned long flags;
755         
756         if (debuglevel >= DEBUG_LEVEL_INFO)     
757                 printk("%s(%d)n_hdlc_tty_ioctl() called %d\n",
758                         __FILE__,__LINE__,cmd);
759                 
760         /* Verify the status of the device */
761         if (!n_hdlc || n_hdlc->magic != HDLC_MAGIC)
762                 return -EBADF;
763
764         switch (cmd) {
765         case FIONREAD:
766                 /* report count of read data available */
767                 /* in next available frame (if any) */
768                 spin_lock_irqsave(&n_hdlc->rx_buf_list.spinlock,flags);
769                 if (n_hdlc->rx_buf_list.head)
770                         count = n_hdlc->rx_buf_list.head->count;
771                 else
772                         count = 0;
773                 spin_unlock_irqrestore(&n_hdlc->rx_buf_list.spinlock,flags);
774                 error = put_user(count, (int __user *)arg);
775                 break;
776
777         case TIOCOUTQ:
778                 /* get the pending tx byte count in the driver */
779                 count = tty_chars_in_buffer(tty);
780                 /* add size of next output frame in queue */
781                 spin_lock_irqsave(&n_hdlc->tx_buf_list.spinlock,flags);
782                 if (n_hdlc->tx_buf_list.head)
783                         count += n_hdlc->tx_buf_list.head->count;
784                 spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock,flags);
785                 error = put_user(count, (int __user *)arg);
786                 break;
787
788         case TCFLSH:
789                 switch (arg) {
790                 case TCIOFLUSH:
791                 case TCOFLUSH:
792                         flush_tx_queue(tty);
793                 }
794                 /* fall through to default */
795
796         default:
797                 error = n_tty_ioctl_helper(tty, file, cmd, arg);
798                 break;
799         }
800         return error;
801         
802 }       /* end of n_hdlc_tty_ioctl() */
803
804 /**
805  * n_hdlc_tty_poll - TTY callback for poll system call
806  * @tty - pointer to tty instance data
807  * @filp - pointer to open file object for device
808  * @poll_table - wait queue for operations
809  * 
810  * Determine which operations (read/write) will not block and return info
811  * to caller.
812  * Returns a bit mask containing info on which ops will not block.
813  */
814 static unsigned int n_hdlc_tty_poll(struct tty_struct *tty, struct file *filp,
815                                     poll_table *wait)
816 {
817         struct n_hdlc *n_hdlc = tty2n_hdlc (tty);
818         unsigned int mask = 0;
819
820         if (debuglevel >= DEBUG_LEVEL_INFO)     
821                 printk("%s(%d)n_hdlc_tty_poll() called\n",__FILE__,__LINE__);
822                 
823         if (n_hdlc && n_hdlc->magic == HDLC_MAGIC && tty == n_hdlc->tty) {
824                 /* queue current process into any wait queue that */
825                 /* may awaken in the future (read and write) */
826
827                 poll_wait(filp, &tty->read_wait, wait);
828                 poll_wait(filp, &tty->write_wait, wait);
829
830                 /* set bits for operations that won't block */
831                 if (n_hdlc->rx_buf_list.head)
832                         mask |= POLLIN | POLLRDNORM;    /* readable */
833                 if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
834                         mask |= POLLHUP;
835                 if (tty_hung_up_p(filp))
836                         mask |= POLLHUP;
837                 if (!tty_is_writelocked(tty) &&
838                                 n_hdlc->tx_free_buf_list.head)
839                         mask |= POLLOUT | POLLWRNORM;   /* writable */
840         }
841         return mask;
842 }       /* end of n_hdlc_tty_poll() */
843
844 /**
845  * n_hdlc_alloc - allocate an n_hdlc instance data structure
846  *
847  * Returns a pointer to newly created structure if success, otherwise %NULL
848  */
849 static struct n_hdlc *n_hdlc_alloc(void)
850 {
851         struct n_hdlc_buf *buf;
852         int i;
853         struct n_hdlc *n_hdlc = kmalloc(sizeof(*n_hdlc), GFP_KERNEL);
854
855         if (!n_hdlc)
856                 return NULL;
857
858         memset(n_hdlc, 0, sizeof(*n_hdlc));
859
860         n_hdlc_buf_list_init(&n_hdlc->rx_free_buf_list);
861         n_hdlc_buf_list_init(&n_hdlc->tx_free_buf_list);
862         n_hdlc_buf_list_init(&n_hdlc->rx_buf_list);
863         n_hdlc_buf_list_init(&n_hdlc->tx_buf_list);
864         
865         /* allocate free rx buffer list */
866         for(i=0;i<DEFAULT_RX_BUF_COUNT;i++) {
867                 buf = kmalloc(N_HDLC_BUF_SIZE, GFP_KERNEL);
868                 if (buf)
869                         n_hdlc_buf_put(&n_hdlc->rx_free_buf_list,buf);
870                 else if (debuglevel >= DEBUG_LEVEL_INFO)        
871                         printk("%s(%d)n_hdlc_alloc(), kalloc() failed for rx buffer %d\n",__FILE__,__LINE__, i);
872         }
873         
874         /* allocate free tx buffer list */
875         for(i=0;i<DEFAULT_TX_BUF_COUNT;i++) {
876                 buf = kmalloc(N_HDLC_BUF_SIZE, GFP_KERNEL);
877                 if (buf)
878                         n_hdlc_buf_put(&n_hdlc->tx_free_buf_list,buf);
879                 else if (debuglevel >= DEBUG_LEVEL_INFO)        
880                         printk("%s(%d)n_hdlc_alloc(), kalloc() failed for tx buffer %d\n",__FILE__,__LINE__, i);
881         }
882         
883         /* Initialize the control block */
884         n_hdlc->magic  = HDLC_MAGIC;
885         n_hdlc->flags  = 0;
886         
887         return n_hdlc;
888         
889 }       /* end of n_hdlc_alloc() */
890
891 /**
892  * n_hdlc_buf_list_init - initialize specified HDLC buffer list
893  * @list - pointer to buffer list
894  */
895 static void n_hdlc_buf_list_init(struct n_hdlc_buf_list *list)
896 {
897         memset(list, 0, sizeof(*list));
898         spin_lock_init(&list->spinlock);
899 }       /* end of n_hdlc_buf_list_init() */
900
901 /**
902  * n_hdlc_buf_put - add specified HDLC buffer to tail of specified list
903  * @list - pointer to buffer list
904  * @buf - pointer to buffer
905  */
906 static void n_hdlc_buf_put(struct n_hdlc_buf_list *list,
907                            struct n_hdlc_buf *buf)
908 {
909         unsigned long flags;
910         spin_lock_irqsave(&list->spinlock,flags);
911         
912         buf->link=NULL;
913         if (list->tail)
914                 list->tail->link = buf;
915         else
916                 list->head = buf;
917         list->tail = buf;
918         (list->count)++;
919         
920         spin_unlock_irqrestore(&list->spinlock,flags);
921         
922 }       /* end of n_hdlc_buf_put() */
923
924 /**
925  * n_hdlc_buf_get - remove and return an HDLC buffer from list
926  * @list - pointer to HDLC buffer list
927  * 
928  * Remove and return an HDLC buffer from the head of the specified HDLC buffer
929  * list.
930  * Returns a pointer to HDLC buffer if available, otherwise %NULL.
931  */
932 static struct n_hdlc_buf* n_hdlc_buf_get(struct n_hdlc_buf_list *list)
933 {
934         unsigned long flags;
935         struct n_hdlc_buf *buf;
936         spin_lock_irqsave(&list->spinlock,flags);
937         
938         buf = list->head;
939         if (buf) {
940                 list->head = buf->link;
941                 (list->count)--;
942         }
943         if (!list->head)
944                 list->tail = NULL;
945         
946         spin_unlock_irqrestore(&list->spinlock,flags);
947         return buf;
948         
949 }       /* end of n_hdlc_buf_get() */
950
951 static char hdlc_banner[] __initdata =
952         KERN_INFO "HDLC line discipline maxframe=%u\n";
953 static char hdlc_register_ok[] __initdata =
954         KERN_INFO "N_HDLC line discipline registered.\n";
955 static char hdlc_register_fail[] __initdata =
956         KERN_ERR "error registering line discipline: %d\n";
957 static char hdlc_init_fail[] __initdata =
958         KERN_INFO "N_HDLC: init failure %d\n";
959
960 static int __init n_hdlc_init(void)
961 {
962         int status;
963
964         /* range check maxframe arg */
965         if (maxframe < 4096)
966                 maxframe = 4096;
967         else if (maxframe > 65535)
968                 maxframe = 65535;
969
970         printk(hdlc_banner, maxframe);
971
972         status = tty_register_ldisc(N_HDLC, &n_hdlc_ldisc);
973         if (!status)
974                 printk(hdlc_register_ok);
975         else
976                 printk(hdlc_register_fail, status);
977
978         if (status)
979                 printk(hdlc_init_fail, status);
980         return status;
981         
982 }       /* end of init_module() */
983
984 static char hdlc_unregister_ok[] __exitdata =
985         KERN_INFO "N_HDLC: line discipline unregistered\n";
986 static char hdlc_unregister_fail[] __exitdata =
987         KERN_ERR "N_HDLC: can't unregister line discipline (err = %d)\n";
988
989 static void __exit n_hdlc_exit(void)
990 {
991         /* Release tty registration of line discipline */
992         int status = tty_unregister_ldisc(N_HDLC);
993
994         if (status)
995                 printk(hdlc_unregister_fail, status);
996         else
997                 printk(hdlc_unregister_ok);
998 }
999
1000 module_init(n_hdlc_init);
1001 module_exit(n_hdlc_exit);
1002
1003 MODULE_LICENSE("GPL");
1004 MODULE_AUTHOR("Paul Fulghum paulkf@microgate.com");
1005 module_param(debuglevel, int, 0);
1006 module_param(maxframe, int, 0);
1007 MODULE_ALIAS_LDISC(N_HDLC);