1
/* generic HDLC line discipline for Linux
3
* Written by Paul Fulghum paulkf@microgate.com
4
* for Microgate Corporation
6
* Microgate and SyncLink are registered trademarks of Microgate Corporation
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>
12
* Original release 01/11/99
14
* This code is released under the GNU General Public License (GPL)
16
* This module implements the tty line discipline N_HDLC for use with
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* tty device drivers that support bit-synchronous HDLC communications.
19
* All HDLC data is frame oriented which means:
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
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* a byte count in the range of 2-65535 bytes (2 is min HDLC frame
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* with 1 addr byte and 1 ctrl byte). The max byte count of 65535
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* should include any crc bytes required. For example, when using
27
* CCITT CRC32, 4 crc bytes are required, so the maximum size frame
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* the application may transmit is limited to 65531 bytes. For CCITT
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* CRC16, the maximum application frame size would be 65533.
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* 2. receive callbacks from the device driver represents
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* one received frame. The device driver should bypass
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* the tty flip buffer and call the line discipline receive
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* callback directly to avoid fragmenting or concatenating
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* multiple frames into a single receive callback.
38
* The HDLC line discipline queues the receive frames in separate
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* buffers so complete receive frames can be returned by the
42
* 3. tty read calls returns an entire frame of data or nothing.
44
* 4. all send and receive data is considered raw. No processing
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* or translation is performed by the line discipline, regardless
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.
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* (instead of the sum of all received frame counts).
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* These conventions allow the standard tty programming interface
54
* to be used for synchronous HDLC applications when used with
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* this line discipline (or another line discipline that is frame
56
* oriented such as N_PPP).
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
63
* This implementation is very basic and does not maintain
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* any statistics. The main point is to enforce the raw data
65
* and frame orientation of HDLC communications.
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* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
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* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
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* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
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* OF THE POSSIBILITY OF SUCH DAMAGE.
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#define HDLC_MAGIC 0x239e
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/sched.h>
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#include <linux/types.h>
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#include <linux/fcntl.h>
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#include <linux/interrupt.h>
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#include <linux/ptrace.h>
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#define VERSION(major,minor,patch) (((((major)<<8)+(minor))<<8)+(patch))
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#include <linux/poll.h>
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#include <linux/ioctl.h>
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#include <linux/slab.h>
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#include <linux/tty.h>
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#include <linux/errno.h>
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#include <linux/smp_lock.h>
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#include <linux/string.h> /* used in new tty drivers */
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#include <linux/signal.h> /* used in new tty drivers */
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#include <linux/if.h>
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#include <linux/bitops.h>
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#include <asm/system.h>
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#include <asm/termios.h>
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#include <asm/uaccess.h>
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* Buffers for individual HDLC frames
113
#define MAX_HDLC_FRAME_SIZE 65535
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#define DEFAULT_RX_BUF_COUNT 10
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#define MAX_RX_BUF_COUNT 60
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#define DEFAULT_TX_BUF_COUNT 3
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struct n_hdlc_buf *link;
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#define N_HDLC_BUF_SIZE (sizeof(struct n_hdlc_buf) + maxframe)
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struct n_hdlc_buf_list {
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struct n_hdlc_buf *head;
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struct n_hdlc_buf *tail;
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* 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
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* @tbuf - currently transmitting tx buffer
142
* @tx_buf_list - list of pending transmit frame buffers
143
* @rx_buf_list - list of received frame buffers
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* @tx_free_buf_list - list unused transmit frame buffers
145
* @rx_free_buf_list - list unused received frame buffers
150
struct tty_struct *tty;
151
struct tty_struct *backup_tty;
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struct n_hdlc_buf *tbuf;
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struct n_hdlc_buf_list tx_buf_list;
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struct n_hdlc_buf_list rx_buf_list;
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struct n_hdlc_buf_list tx_free_buf_list;
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struct n_hdlc_buf_list rx_free_buf_list;
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* HDLC buffer list manipulation functions
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);
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static struct n_hdlc_buf *n_hdlc_buf_get(struct n_hdlc_buf_list *list);
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/* Local functions */
171
static struct n_hdlc *n_hdlc_alloc (void);
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/* debug level can be set by insmod for debugging purposes */
174
#define DEBUG_LEVEL_INFO 1
175
static int debuglevel;
177
/* max frame size for memory allocations */
178
static int maxframe = 4096;
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,
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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);
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#define bset(p,b) ((p)[(b) >> 5] |= (1 << ((b) & 0x1f)))
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#define tty2n_hdlc(tty) ((struct n_hdlc *) ((tty)->disc_data))
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#define n_hdlc2tty(n_hdlc) ((n_hdlc)->tty)
201
static void flush_rx_queue(struct tty_struct *tty)
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struct n_hdlc *n_hdlc = tty2n_hdlc(tty);
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struct n_hdlc_buf *buf;
206
while ((buf = n_hdlc_buf_get(&n_hdlc->rx_buf_list)))
207
n_hdlc_buf_put(&n_hdlc->rx_free_buf_list, buf);
210
static void flush_tx_queue(struct tty_struct *tty)
212
struct n_hdlc *n_hdlc = tty2n_hdlc(tty);
213
struct n_hdlc_buf *buf;
216
while ((buf = n_hdlc_buf_get(&n_hdlc->tx_buf_list)))
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n_hdlc_buf_put(&n_hdlc->tx_free_buf_list, buf);
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spin_lock_irqsave(&n_hdlc->tx_buf_list.spinlock, flags);
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n_hdlc_buf_put(&n_hdlc->tx_free_buf_list, n_hdlc->tbuf);
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spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags);
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static struct tty_ldisc_ops n_hdlc_ldisc = {
227
.owner = THIS_MODULE,
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.magic = TTY_LDISC_MAGIC,
230
.open = n_hdlc_tty_open,
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.close = n_hdlc_tty_close,
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.read = n_hdlc_tty_read,
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.write = n_hdlc_tty_write,
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.ioctl = n_hdlc_tty_ioctl,
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.poll = n_hdlc_tty_poll,
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.receive_buf = n_hdlc_tty_receive,
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.write_wakeup = n_hdlc_tty_wakeup,
238
.flush_buffer = flush_rx_queue,
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* n_hdlc_release - release an n_hdlc per device line discipline info structure
243
* @n_hdlc - per device line discipline info structure
245
static void n_hdlc_release(struct n_hdlc *n_hdlc)
247
struct tty_struct *tty = n_hdlc2tty (n_hdlc);
248
struct n_hdlc_buf *buf;
250
if (debuglevel >= DEBUG_LEVEL_INFO)
251
printk("%s(%d)n_hdlc_release() called\n",__FILE__,__LINE__);
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);
257
if (tty->disc_data == n_hdlc)
258
tty->disc_data = NULL; /* Break the tty->n_hdlc link */
260
/* Release transmit and receive buffers */
262
buf = n_hdlc_buf_get(&n_hdlc->rx_free_buf_list);
269
buf = n_hdlc_buf_get(&n_hdlc->tx_free_buf_list);
276
buf = n_hdlc_buf_get(&n_hdlc->rx_buf_list);
283
buf = n_hdlc_buf_get(&n_hdlc->tx_buf_list);
292
} /* end of n_hdlc_release() */
295
* n_hdlc_tty_close - line discipline close
296
* @tty - pointer to tty info structure
298
* Called when the line discipline is changed to something
299
* else, the tty is closed, or the tty detects a hangup.
301
static void n_hdlc_tty_close(struct tty_struct *tty)
303
struct n_hdlc *n_hdlc = tty2n_hdlc (tty);
305
if (debuglevel >= DEBUG_LEVEL_INFO)
306
printk("%s(%d)n_hdlc_tty_close() called\n",__FILE__,__LINE__);
308
if (n_hdlc != NULL) {
309
if (n_hdlc->magic != HDLC_MAGIC) {
310
printk (KERN_WARNING"n_hdlc: trying to close unopened tty!\n");
313
#if defined(TTY_NO_WRITE_SPLIT)
314
clear_bit(TTY_NO_WRITE_SPLIT,&tty->flags);
316
tty->disc_data = NULL;
317
if (tty == n_hdlc->backup_tty)
318
n_hdlc->backup_tty = NULL;
319
if (tty != n_hdlc->tty)
321
if (n_hdlc->backup_tty) {
322
n_hdlc->tty = n_hdlc->backup_tty;
324
n_hdlc_release (n_hdlc);
328
if (debuglevel >= DEBUG_LEVEL_INFO)
329
printk("%s(%d)n_hdlc_tty_close() success\n",__FILE__,__LINE__);
331
} /* end of n_hdlc_tty_close() */
334
* n_hdlc_tty_open - called when line discipline changed to n_hdlc
335
* @tty - pointer to tty info structure
337
* Returns 0 if success, otherwise error code
339
static int n_hdlc_tty_open (struct tty_struct *tty)
341
struct n_hdlc *n_hdlc = tty2n_hdlc (tty);
343
if (debuglevel >= DEBUG_LEVEL_INFO)
344
printk("%s(%d)n_hdlc_tty_open() called (device=%s)\n",
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/* There should not be an existing table for this slot. */
350
printk (KERN_ERR"n_hdlc_tty_open:tty already associated!\n" );
354
n_hdlc = n_hdlc_alloc();
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printk (KERN_ERR "n_hdlc_alloc failed\n");
360
tty->disc_data = n_hdlc;
362
tty->receive_room = 65536;
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#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);
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/* flush receive data from driver */
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tty_driver_flush_buffer(tty);
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if (debuglevel >= DEBUG_LEVEL_INFO)
373
printk("%s(%d)n_hdlc_tty_open() success\n",__FILE__,__LINE__);
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} /* end of n_tty_hdlc_open() */
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
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.
388
static void n_hdlc_send_frames(struct n_hdlc *n_hdlc, struct tty_struct *tty)
392
struct n_hdlc_buf *tbuf;
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if (debuglevel >= DEBUG_LEVEL_INFO)
395
printk("%s(%d)n_hdlc_send_frames() called\n",__FILE__,__LINE__);
398
spin_lock_irqsave(&n_hdlc->tx_buf_list.spinlock, flags);
401
spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags);
406
spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags);
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/* get current transmit buffer or get new transmit */
409
/* buffer from list of pending transmit buffers */
413
tbuf = n_hdlc_buf_get(&n_hdlc->tx_buf_list);
416
if (debuglevel >= DEBUG_LEVEL_INFO)
417
printk("%s(%d)sending frame %p, count=%d\n",
418
__FILE__,__LINE__,tbuf,tbuf->count);
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/* 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);
424
/* rollback was possible and has been done */
425
if (actual == -ERESTARTSYS) {
429
/* if transmit error, throw frame away by */
430
/* pretending it was accepted by driver */
432
actual = tbuf->count;
434
if (actual == tbuf->count) {
435
if (debuglevel >= DEBUG_LEVEL_INFO)
436
printk("%s(%d)frame %p completed\n",
437
__FILE__,__LINE__,tbuf);
439
/* free current transmit buffer */
440
n_hdlc_buf_put(&n_hdlc->tx_free_buf_list, tbuf);
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/* this tx buffer is done */
445
/* wait up sleeping writers */
446
wake_up_interruptible(&tty->write_wait);
448
/* get next pending transmit buffer */
449
tbuf = n_hdlc_buf_get(&n_hdlc->tx_buf_list);
451
if (debuglevel >= DEBUG_LEVEL_INFO)
452
printk("%s(%d)frame %p pending\n",
453
__FILE__,__LINE__,tbuf);
455
/* buffer not accepted by driver */
456
/* set this buffer as pending buffer */
463
tty->flags &= ~(1 << TTY_DO_WRITE_WAKEUP);
465
/* Clear the re-entry flag */
466
spin_lock_irqsave(&n_hdlc->tx_buf_list.spinlock, flags);
468
spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags);
473
if (debuglevel >= DEBUG_LEVEL_INFO)
474
printk("%s(%d)n_hdlc_send_frames() exit\n",__FILE__,__LINE__);
476
} /* end of n_hdlc_send_frames() */
479
* n_hdlc_tty_wakeup - Callback for transmit wakeup
480
* @tty - pointer to associated tty instance data
482
* Called when low level device driver can accept more send data.
484
static void n_hdlc_tty_wakeup(struct tty_struct *tty)
486
struct n_hdlc *n_hdlc = tty2n_hdlc(tty);
488
if (debuglevel >= DEBUG_LEVEL_INFO)
489
printk("%s(%d)n_hdlc_tty_wakeup() called\n",__FILE__,__LINE__);
494
if (tty != n_hdlc->tty) {
495
tty->flags &= ~(1 << TTY_DO_WRITE_WAKEUP);
499
n_hdlc_send_frames (n_hdlc, tty);
501
} /* end of n_hdlc_tty_wakeup() */
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
510
* Called by tty low level driver when receive data is available. Data is
511
* interpreted as one HDLC frame.
513
static void n_hdlc_tty_receive(struct tty_struct *tty, const __u8 *data,
514
char *flags, int count)
516
register struct n_hdlc *n_hdlc = tty2n_hdlc (tty);
517
register struct n_hdlc_buf *buf;
519
if (debuglevel >= DEBUG_LEVEL_INFO)
520
printk("%s(%d)n_hdlc_tty_receive() called count=%d\n",
521
__FILE__,__LINE__, count);
523
/* This can happen if stuff comes in on the backup tty */
524
if (!n_hdlc || tty != n_hdlc->tty)
527
/* verify line is using HDLC discipline */
528
if (n_hdlc->magic != HDLC_MAGIC) {
529
printk("%s(%d) line not using HDLC discipline\n",
534
if ( count>maxframe ) {
535
if (debuglevel >= DEBUG_LEVEL_INFO)
536
printk("%s(%d) rx count>maxframesize, data discarded\n",
541
/* get a free HDLC buffer */
542
buf = n_hdlc_buf_get(&n_hdlc->rx_free_buf_list);
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);
551
if (debuglevel >= DEBUG_LEVEL_INFO)
552
printk("%s(%d) no more rx buffers, data discarded\n",
557
/* copy received data to HDLC buffer */
558
memcpy(buf->buf,data,count);
561
/* add HDLC buffer to list of received frames */
562
n_hdlc_buf_put(&n_hdlc->rx_buf_list, buf);
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);
569
} /* end of n_hdlc_tty_receive() */
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
578
* Returns the number of bytes returned or error code.
580
static ssize_t n_hdlc_tty_read(struct tty_struct *tty, struct file *file,
581
__u8 __user *buf, size_t nr)
583
struct n_hdlc *n_hdlc = tty2n_hdlc(tty);
585
struct n_hdlc_buf *rbuf;
586
DECLARE_WAITQUEUE(wait, current);
588
if (debuglevel >= DEBUG_LEVEL_INFO)
589
printk("%s(%d)n_hdlc_tty_read() called\n",__FILE__,__LINE__);
591
/* Validate the pointers */
595
/* verify user access to buffer */
596
if (!access_ok(VERIFY_WRITE, buf, nr)) {
597
printk(KERN_WARNING "%s(%d) n_hdlc_tty_read() can't verify user "
598
"buffer\n", __FILE__, __LINE__);
602
add_wait_queue(&tty->read_wait, &wait);
605
if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) {
609
if (tty_hung_up_p(file))
612
set_current_state(TASK_INTERRUPTIBLE);
614
rbuf = n_hdlc_buf_get(&n_hdlc->rx_buf_list);
616
if (rbuf->count > nr) {
617
/* too large for caller's buffer */
620
if (copy_to_user(buf, rbuf->buf, rbuf->count))
626
if (n_hdlc->rx_free_buf_list.count >
627
DEFAULT_RX_BUF_COUNT)
630
n_hdlc_buf_put(&n_hdlc->rx_free_buf_list, rbuf);
635
if (file->f_flags & O_NONBLOCK) {
642
if (signal_pending(current)) {
648
remove_wait_queue(&tty->read_wait, &wait);
649
__set_current_state(TASK_RUNNING);
653
} /* end of n_hdlc_tty_read() */
656
* n_hdlc_tty_write - write a single frame of data to device
657
* @tty - pointer to associated tty device instance data
658
* @file - pointer to file object data
659
* @data - pointer to transmit data (one frame)
660
* @count - size of transmit frame in bytes
662
* Returns the number of bytes written (or error code).
664
static ssize_t n_hdlc_tty_write(struct tty_struct *tty, struct file *file,
665
const unsigned char *data, size_t count)
667
struct n_hdlc *n_hdlc = tty2n_hdlc (tty);
669
DECLARE_WAITQUEUE(wait, current);
670
struct n_hdlc_buf *tbuf;
672
if (debuglevel >= DEBUG_LEVEL_INFO)
673
printk("%s(%d)n_hdlc_tty_write() called count=%Zd\n",
674
__FILE__,__LINE__,count);
676
/* Verify pointers */
680
if (n_hdlc->magic != HDLC_MAGIC)
683
/* verify frame size */
684
if (count > maxframe ) {
685
if (debuglevel & DEBUG_LEVEL_INFO)
687
"n_hdlc_tty_write: truncating user packet "
688
"from %lu to %d\n", (unsigned long) count,
693
add_wait_queue(&tty->write_wait, &wait);
696
set_current_state(TASK_INTERRUPTIBLE);
698
tbuf = n_hdlc_buf_get(&n_hdlc->tx_free_buf_list);
702
if (file->f_flags & O_NONBLOCK) {
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);
716
if (signal_pending(current)) {
722
__set_current_state(TASK_RUNNING);
723
remove_wait_queue(&tty->write_wait, &wait);
726
/* Retrieve the user's buffer */
727
memcpy(tbuf->buf, data, count);
730
tbuf->count = error = count;
731
n_hdlc_buf_put(&n_hdlc->tx_buf_list,tbuf);
732
n_hdlc_send_frames(n_hdlc,tty);
737
} /* end of n_hdlc_tty_write() */
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)
746
* Returns command dependent result.
748
static int n_hdlc_tty_ioctl(struct tty_struct *tty, struct file *file,
749
unsigned int cmd, unsigned long arg)
751
struct n_hdlc *n_hdlc = tty2n_hdlc (tty);
756
if (debuglevel >= DEBUG_LEVEL_INFO)
757
printk("%s(%d)n_hdlc_tty_ioctl() called %d\n",
758
__FILE__,__LINE__,cmd);
760
/* Verify the status of the device */
761
if (!n_hdlc || n_hdlc->magic != HDLC_MAGIC)
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;
773
spin_unlock_irqrestore(&n_hdlc->rx_buf_list.spinlock,flags);
774
error = put_user(count, (int __user *)arg);
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);
794
/* fall through to default */
797
error = n_tty_ioctl_helper(tty, file, cmd, arg);
802
} /* end of n_hdlc_tty_ioctl() */
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
810
* Determine which operations (read/write) will not block and return info
812
* Returns a bit mask containing info on which ops will not block.
814
static unsigned int n_hdlc_tty_poll(struct tty_struct *tty, struct file *filp,
817
struct n_hdlc *n_hdlc = tty2n_hdlc (tty);
818
unsigned int mask = 0;
820
if (debuglevel >= DEBUG_LEVEL_INFO)
821
printk("%s(%d)n_hdlc_tty_poll() called\n",__FILE__,__LINE__);
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) */
827
poll_wait(filp, &tty->read_wait, wait);
828
poll_wait(filp, &tty->write_wait, wait);
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))
835
if (tty_hung_up_p(filp))
837
if (!tty_is_writelocked(tty) &&
838
n_hdlc->tx_free_buf_list.head)
839
mask |= POLLOUT | POLLWRNORM; /* writable */
842
} /* end of n_hdlc_tty_poll() */
845
* n_hdlc_alloc - allocate an n_hdlc instance data structure
847
* Returns a pointer to newly created structure if success, otherwise %NULL
849
static struct n_hdlc *n_hdlc_alloc(void)
851
struct n_hdlc_buf *buf;
853
struct n_hdlc *n_hdlc = kmalloc(sizeof(*n_hdlc), GFP_KERNEL);
858
memset(n_hdlc, 0, sizeof(*n_hdlc));
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);
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);
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);
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);
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);
883
/* Initialize the control block */
884
n_hdlc->magic = HDLC_MAGIC;
889
} /* end of n_hdlc_alloc() */
892
* n_hdlc_buf_list_init - initialize specified HDLC buffer list
893
* @list - pointer to buffer list
895
static void n_hdlc_buf_list_init(struct n_hdlc_buf_list *list)
897
memset(list, 0, sizeof(*list));
898
spin_lock_init(&list->spinlock);
899
} /* end of n_hdlc_buf_list_init() */
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
906
static void n_hdlc_buf_put(struct n_hdlc_buf_list *list,
907
struct n_hdlc_buf *buf)
910
spin_lock_irqsave(&list->spinlock,flags);
914
list->tail->link = buf;
920
spin_unlock_irqrestore(&list->spinlock,flags);
922
} /* end of n_hdlc_buf_put() */
925
* n_hdlc_buf_get - remove and return an HDLC buffer from list
926
* @list - pointer to HDLC buffer list
928
* Remove and return an HDLC buffer from the head of the specified HDLC buffer
930
* Returns a pointer to HDLC buffer if available, otherwise %NULL.
932
static struct n_hdlc_buf* n_hdlc_buf_get(struct n_hdlc_buf_list *list)
935
struct n_hdlc_buf *buf;
936
spin_lock_irqsave(&list->spinlock,flags);
940
list->head = buf->link;
946
spin_unlock_irqrestore(&list->spinlock,flags);
949
} /* end of n_hdlc_buf_get() */
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";
960
static int __init n_hdlc_init(void)
964
/* range check maxframe arg */
967
else if (maxframe > 65535)
970
printk(hdlc_banner, maxframe);
972
status = tty_register_ldisc(N_HDLC, &n_hdlc_ldisc);
974
printk(hdlc_register_ok);
976
printk(hdlc_register_fail, status);
979
printk(hdlc_init_fail, status);
982
} /* end of init_module() */
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";
989
static void __exit n_hdlc_exit(void)
991
/* Release tty registration of line discipline */
992
int status = tty_unregister_ldisc(N_HDLC);
995
printk(hdlc_unregister_fail, status);
997
printk(hdlc_unregister_ok);
1000
module_init(n_hdlc_init);
1001
module_exit(n_hdlc_exit);
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);