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- // SPDX-License-Identifier: GPL-1.0+
- /* generic HDLC line discipline for Linux
- *
- * Written by Paul Fulghum paulkf@microgate.com
- * for Microgate Corporation
- *
- * Microgate and SyncLink are registered trademarks of Microgate Corporation
- *
- * Adapted from ppp.c, written by Michael Callahan <callahan@maths.ox.ac.uk>,
- * Al Longyear <longyear@netcom.com>,
- * Paul Mackerras <Paul.Mackerras@cs.anu.edu.au>
- *
- * Original release 01/11/99
- *
- * This module implements the tty line discipline N_HDLC for use with
- * tty device drivers that support bit-synchronous HDLC communications.
- *
- * All HDLC data is frame oriented which means:
- *
- * 1. tty write calls represent one complete transmit frame of data
- * The device driver should accept the complete frame or none of
- * the frame (busy) in the write method. Each write call should have
- * a byte count in the range of 2-65535 bytes (2 is min HDLC frame
- * with 1 addr byte and 1 ctrl byte). The max byte count of 65535
- * should include any crc bytes required. For example, when using
- * CCITT CRC32, 4 crc bytes are required, so the maximum size frame
- * the application may transmit is limited to 65531 bytes. For CCITT
- * CRC16, the maximum application frame size would be 65533.
- *
- *
- * 2. receive callbacks from the device driver represents
- * one received frame. The device driver should bypass
- * the tty flip buffer and call the line discipline receive
- * callback directly to avoid fragmenting or concatenating
- * multiple frames into a single receive callback.
- *
- * The HDLC line discipline queues the receive frames in separate
- * buffers so complete receive frames can be returned by the
- * tty read calls.
- *
- * 3. tty read calls returns an entire frame of data or nothing.
- *
- * 4. all send and receive data is considered raw. No processing
- * or translation is performed by the line discipline, regardless
- * of the tty flags
- *
- * 5. When line discipline is queried for the amount of receive
- * data available (FIOC), 0 is returned if no data available,
- * otherwise the count of the next available frame is returned.
- * (instead of the sum of all received frame counts).
- *
- * These conventions allow the standard tty programming interface
- * to be used for synchronous HDLC applications when used with
- * this line discipline (or another line discipline that is frame
- * oriented such as N_PPP).
- *
- * The SyncLink driver (synclink.c) implements both asynchronous
- * (using standard line discipline N_TTY) and synchronous HDLC
- * (using N_HDLC) communications, with the latter using the above
- * conventions.
- *
- * This implementation is very basic and does not maintain
- * any statistics. The main point is to enforce the raw data
- * and frame orientation of HDLC communications.
- *
- * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
- * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
- * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
- * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
- * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
- * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
- * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
- * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
- * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
- * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
- * OF THE POSSIBILITY OF SUCH DAMAGE.
- */
- #define HDLC_MAGIC 0x239e
- #include <linux/module.h>
- #include <linux/init.h>
- #include <linux/kernel.h>
- #include <linux/sched.h>
- #include <linux/types.h>
- #include <linux/fcntl.h>
- #include <linux/interrupt.h>
- #include <linux/ptrace.h>
- #undef VERSION
- #define VERSION(major,minor,patch) (((((major)<<8)+(minor))<<8)+(patch))
- #include <linux/poll.h>
- #include <linux/in.h>
- #include <linux/ioctl.h>
- #include <linux/slab.h>
- #include <linux/tty.h>
- #include <linux/errno.h>
- #include <linux/string.h> /* used in new tty drivers */
- #include <linux/signal.h> /* used in new tty drivers */
- #include <linux/if.h>
- #include <linux/bitops.h>
- #include <asm/termios.h>
- #include <linux/uaccess.h>
- /*
- * Buffers for individual HDLC frames
- */
- #define MAX_HDLC_FRAME_SIZE 65535
- #define DEFAULT_RX_BUF_COUNT 10
- #define MAX_RX_BUF_COUNT 60
- #define DEFAULT_TX_BUF_COUNT 3
- struct n_hdlc_buf {
- struct list_head list_item;
- int count;
- char buf[1];
- };
- #define N_HDLC_BUF_SIZE (sizeof(struct n_hdlc_buf) + maxframe)
- struct n_hdlc_buf_list {
- struct list_head list;
- int count;
- spinlock_t spinlock;
- };
- /**
- * struct n_hdlc - per device instance data structure
- * @magic - magic value for structure
- * @flags - miscellaneous control flags
- * @tty - ptr to TTY structure
- * @backup_tty - TTY to use if tty gets closed
- * @tbusy - reentrancy flag for tx wakeup code
- * @woke_up - FIXME: describe this field
- * @tx_buf_list - list of pending transmit frame buffers
- * @rx_buf_list - list of received frame buffers
- * @tx_free_buf_list - list unused transmit frame buffers
- * @rx_free_buf_list - list unused received frame buffers
- */
- struct n_hdlc {
- int magic;
- __u32 flags;
- struct tty_struct *tty;
- struct tty_struct *backup_tty;
- int tbusy;
- int woke_up;
- struct n_hdlc_buf_list tx_buf_list;
- struct n_hdlc_buf_list rx_buf_list;
- struct n_hdlc_buf_list tx_free_buf_list;
- struct n_hdlc_buf_list rx_free_buf_list;
- };
- /*
- * HDLC buffer list manipulation functions
- */
- static void n_hdlc_buf_return(struct n_hdlc_buf_list *buf_list,
- struct n_hdlc_buf *buf);
- static void n_hdlc_buf_put(struct n_hdlc_buf_list *list,
- struct n_hdlc_buf *buf);
- static struct n_hdlc_buf *n_hdlc_buf_get(struct n_hdlc_buf_list *list);
- /* Local functions */
- static struct n_hdlc *n_hdlc_alloc (void);
- /* debug level can be set by insmod for debugging purposes */
- #define DEBUG_LEVEL_INFO 1
- static int debuglevel;
- /* max frame size for memory allocations */
- static int maxframe = 4096;
- /* TTY callbacks */
- static ssize_t n_hdlc_tty_read(struct tty_struct *tty, struct file *file,
- __u8 __user *buf, size_t nr);
- static ssize_t n_hdlc_tty_write(struct tty_struct *tty, struct file *file,
- const unsigned char *buf, size_t nr);
- static int n_hdlc_tty_ioctl(struct tty_struct *tty, struct file *file,
- unsigned int cmd, unsigned long arg);
- static __poll_t n_hdlc_tty_poll(struct tty_struct *tty, struct file *filp,
- poll_table *wait);
- static int n_hdlc_tty_open(struct tty_struct *tty);
- static void n_hdlc_tty_close(struct tty_struct *tty);
- static void n_hdlc_tty_receive(struct tty_struct *tty, const __u8 *cp,
- char *fp, int count);
- static void n_hdlc_tty_wakeup(struct tty_struct *tty);
- #define bset(p,b) ((p)[(b) >> 5] |= (1 << ((b) & 0x1f)))
- #define tty2n_hdlc(tty) ((struct n_hdlc *) ((tty)->disc_data))
- #define n_hdlc2tty(n_hdlc) ((n_hdlc)->tty)
- static void flush_rx_queue(struct tty_struct *tty)
- {
- struct n_hdlc *n_hdlc = tty2n_hdlc(tty);
- struct n_hdlc_buf *buf;
- while ((buf = n_hdlc_buf_get(&n_hdlc->rx_buf_list)))
- n_hdlc_buf_put(&n_hdlc->rx_free_buf_list, buf);
- }
- static void flush_tx_queue(struct tty_struct *tty)
- {
- struct n_hdlc *n_hdlc = tty2n_hdlc(tty);
- struct n_hdlc_buf *buf;
- while ((buf = n_hdlc_buf_get(&n_hdlc->tx_buf_list)))
- n_hdlc_buf_put(&n_hdlc->tx_free_buf_list, buf);
- }
- static struct tty_ldisc_ops n_hdlc_ldisc = {
- .owner = THIS_MODULE,
- .magic = TTY_LDISC_MAGIC,
- .name = "hdlc",
- .open = n_hdlc_tty_open,
- .close = n_hdlc_tty_close,
- .read = n_hdlc_tty_read,
- .write = n_hdlc_tty_write,
- .ioctl = n_hdlc_tty_ioctl,
- .poll = n_hdlc_tty_poll,
- .receive_buf = n_hdlc_tty_receive,
- .write_wakeup = n_hdlc_tty_wakeup,
- .flush_buffer = flush_rx_queue,
- };
- /**
- * n_hdlc_release - release an n_hdlc per device line discipline info structure
- * @n_hdlc - per device line discipline info structure
- */
- static void n_hdlc_release(struct n_hdlc *n_hdlc)
- {
- struct tty_struct *tty = n_hdlc2tty (n_hdlc);
- struct n_hdlc_buf *buf;
-
- if (debuglevel >= DEBUG_LEVEL_INFO)
- printk("%s(%d)n_hdlc_release() called\n",__FILE__,__LINE__);
-
- /* Ensure that the n_hdlcd process is not hanging on select()/poll() */
- wake_up_interruptible (&tty->read_wait);
- wake_up_interruptible (&tty->write_wait);
- if (tty->disc_data == n_hdlc)
- tty->disc_data = NULL; /* Break the tty->n_hdlc link */
- /* Release transmit and receive buffers */
- for(;;) {
- buf = n_hdlc_buf_get(&n_hdlc->rx_free_buf_list);
- if (buf) {
- kfree(buf);
- } else
- break;
- }
- for(;;) {
- buf = n_hdlc_buf_get(&n_hdlc->tx_free_buf_list);
- if (buf) {
- kfree(buf);
- } else
- break;
- }
- for(;;) {
- buf = n_hdlc_buf_get(&n_hdlc->rx_buf_list);
- if (buf) {
- kfree(buf);
- } else
- break;
- }
- for(;;) {
- buf = n_hdlc_buf_get(&n_hdlc->tx_buf_list);
- if (buf) {
- kfree(buf);
- } else
- break;
- }
- kfree(n_hdlc);
-
- } /* end of n_hdlc_release() */
- /**
- * n_hdlc_tty_close - line discipline close
- * @tty - pointer to tty info structure
- *
- * Called when the line discipline is changed to something
- * else, the tty is closed, or the tty detects a hangup.
- */
- static void n_hdlc_tty_close(struct tty_struct *tty)
- {
- struct n_hdlc *n_hdlc = tty2n_hdlc (tty);
- if (debuglevel >= DEBUG_LEVEL_INFO)
- printk("%s(%d)n_hdlc_tty_close() called\n",__FILE__,__LINE__);
-
- if (n_hdlc != NULL) {
- if (n_hdlc->magic != HDLC_MAGIC) {
- printk (KERN_WARNING"n_hdlc: trying to close unopened tty!\n");
- return;
- }
- #if defined(TTY_NO_WRITE_SPLIT)
- clear_bit(TTY_NO_WRITE_SPLIT,&tty->flags);
- #endif
- tty->disc_data = NULL;
- if (tty == n_hdlc->backup_tty)
- n_hdlc->backup_tty = NULL;
- if (tty != n_hdlc->tty)
- return;
- if (n_hdlc->backup_tty) {
- n_hdlc->tty = n_hdlc->backup_tty;
- } else {
- n_hdlc_release (n_hdlc);
- }
- }
-
- if (debuglevel >= DEBUG_LEVEL_INFO)
- printk("%s(%d)n_hdlc_tty_close() success\n",__FILE__,__LINE__);
-
- } /* end of n_hdlc_tty_close() */
- /**
- * n_hdlc_tty_open - called when line discipline changed to n_hdlc
- * @tty - pointer to tty info structure
- *
- * Returns 0 if success, otherwise error code
- */
- static int n_hdlc_tty_open (struct tty_struct *tty)
- {
- struct n_hdlc *n_hdlc = tty2n_hdlc (tty);
- if (debuglevel >= DEBUG_LEVEL_INFO)
- printk("%s(%d)n_hdlc_tty_open() called (device=%s)\n",
- __FILE__,__LINE__,
- tty->name);
-
- /* There should not be an existing table for this slot. */
- if (n_hdlc) {
- printk (KERN_ERR"n_hdlc_tty_open:tty already associated!\n" );
- return -EEXIST;
- }
-
- n_hdlc = n_hdlc_alloc();
- if (!n_hdlc) {
- printk (KERN_ERR "n_hdlc_alloc failed\n");
- return -ENFILE;
- }
-
- tty->disc_data = n_hdlc;
- n_hdlc->tty = tty;
- tty->receive_room = 65536;
-
- #if defined(TTY_NO_WRITE_SPLIT)
- /* change tty_io write() to not split large writes into 8K chunks */
- set_bit(TTY_NO_WRITE_SPLIT,&tty->flags);
- #endif
-
- /* flush receive data from driver */
- tty_driver_flush_buffer(tty);
-
- if (debuglevel >= DEBUG_LEVEL_INFO)
- printk("%s(%d)n_hdlc_tty_open() success\n",__FILE__,__LINE__);
-
- return 0;
-
- } /* end of n_tty_hdlc_open() */
- /**
- * n_hdlc_send_frames - send frames on pending send buffer list
- * @n_hdlc - pointer to ldisc instance data
- * @tty - pointer to tty instance data
- *
- * Send frames on pending send buffer list until the driver does not accept a
- * frame (busy) this function is called after adding a frame to the send buffer
- * list and by the tty wakeup callback.
- */
- static void n_hdlc_send_frames(struct n_hdlc *n_hdlc, struct tty_struct *tty)
- {
- register int actual;
- unsigned long flags;
- struct n_hdlc_buf *tbuf;
- if (debuglevel >= DEBUG_LEVEL_INFO)
- printk("%s(%d)n_hdlc_send_frames() called\n",__FILE__,__LINE__);
- check_again:
-
- spin_lock_irqsave(&n_hdlc->tx_buf_list.spinlock, flags);
- if (n_hdlc->tbusy) {
- n_hdlc->woke_up = 1;
- spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags);
- return;
- }
- n_hdlc->tbusy = 1;
- n_hdlc->woke_up = 0;
- spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags);
- tbuf = n_hdlc_buf_get(&n_hdlc->tx_buf_list);
- while (tbuf) {
- if (debuglevel >= DEBUG_LEVEL_INFO)
- printk("%s(%d)sending frame %p, count=%d\n",
- __FILE__,__LINE__,tbuf,tbuf->count);
-
- /* Send the next block of data to device */
- set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
- actual = tty->ops->write(tty, tbuf->buf, tbuf->count);
- /* rollback was possible and has been done */
- if (actual == -ERESTARTSYS) {
- n_hdlc_buf_return(&n_hdlc->tx_buf_list, tbuf);
- break;
- }
- /* if transmit error, throw frame away by */
- /* pretending it was accepted by driver */
- if (actual < 0)
- actual = tbuf->count;
-
- if (actual == tbuf->count) {
- if (debuglevel >= DEBUG_LEVEL_INFO)
- printk("%s(%d)frame %p completed\n",
- __FILE__,__LINE__,tbuf);
-
- /* free current transmit buffer */
- n_hdlc_buf_put(&n_hdlc->tx_free_buf_list, tbuf);
- /* wait up sleeping writers */
- wake_up_interruptible(&tty->write_wait);
-
- /* get next pending transmit buffer */
- tbuf = n_hdlc_buf_get(&n_hdlc->tx_buf_list);
- } else {
- if (debuglevel >= DEBUG_LEVEL_INFO)
- printk("%s(%d)frame %p pending\n",
- __FILE__,__LINE__,tbuf);
- /*
- * the buffer was not accepted by driver,
- * return it back into tx queue
- */
- n_hdlc_buf_return(&n_hdlc->tx_buf_list, tbuf);
- break;
- }
- }
-
- if (!tbuf)
- clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
-
- /* Clear the re-entry flag */
- spin_lock_irqsave(&n_hdlc->tx_buf_list.spinlock, flags);
- n_hdlc->tbusy = 0;
- spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags);
-
- if (n_hdlc->woke_up)
- goto check_again;
- if (debuglevel >= DEBUG_LEVEL_INFO)
- printk("%s(%d)n_hdlc_send_frames() exit\n",__FILE__,__LINE__);
-
- } /* end of n_hdlc_send_frames() */
- /**
- * n_hdlc_tty_wakeup - Callback for transmit wakeup
- * @tty - pointer to associated tty instance data
- *
- * Called when low level device driver can accept more send data.
- */
- static void n_hdlc_tty_wakeup(struct tty_struct *tty)
- {
- struct n_hdlc *n_hdlc = tty2n_hdlc(tty);
- if (debuglevel >= DEBUG_LEVEL_INFO)
- printk("%s(%d)n_hdlc_tty_wakeup() called\n",__FILE__,__LINE__);
-
- if (!n_hdlc)
- return;
- if (tty != n_hdlc->tty) {
- clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
- return;
- }
- n_hdlc_send_frames (n_hdlc, tty);
-
- } /* end of n_hdlc_tty_wakeup() */
- /**
- * n_hdlc_tty_receive - Called by tty driver when receive data is available
- * @tty - pointer to tty instance data
- * @data - pointer to received data
- * @flags - pointer to flags for data
- * @count - count of received data in bytes
- *
- * Called by tty low level driver when receive data is available. Data is
- * interpreted as one HDLC frame.
- */
- static void n_hdlc_tty_receive(struct tty_struct *tty, const __u8 *data,
- char *flags, int count)
- {
- register struct n_hdlc *n_hdlc = tty2n_hdlc (tty);
- register struct n_hdlc_buf *buf;
- if (debuglevel >= DEBUG_LEVEL_INFO)
- printk("%s(%d)n_hdlc_tty_receive() called count=%d\n",
- __FILE__,__LINE__, count);
-
- /* This can happen if stuff comes in on the backup tty */
- if (!n_hdlc || tty != n_hdlc->tty)
- return;
-
- /* verify line is using HDLC discipline */
- if (n_hdlc->magic != HDLC_MAGIC) {
- printk("%s(%d) line not using HDLC discipline\n",
- __FILE__,__LINE__);
- return;
- }
-
- if ( count>maxframe ) {
- if (debuglevel >= DEBUG_LEVEL_INFO)
- printk("%s(%d) rx count>maxframesize, data discarded\n",
- __FILE__,__LINE__);
- return;
- }
- /* get a free HDLC buffer */
- buf = n_hdlc_buf_get(&n_hdlc->rx_free_buf_list);
- if (!buf) {
- /* no buffers in free list, attempt to allocate another rx buffer */
- /* unless the maximum count has been reached */
- if (n_hdlc->rx_buf_list.count < MAX_RX_BUF_COUNT)
- buf = kmalloc(N_HDLC_BUF_SIZE, GFP_ATOMIC);
- }
-
- if (!buf) {
- if (debuglevel >= DEBUG_LEVEL_INFO)
- printk("%s(%d) no more rx buffers, data discarded\n",
- __FILE__,__LINE__);
- return;
- }
-
- /* copy received data to HDLC buffer */
- memcpy(buf->buf,data,count);
- buf->count=count;
- /* add HDLC buffer to list of received frames */
- n_hdlc_buf_put(&n_hdlc->rx_buf_list, buf);
-
- /* wake up any blocked reads and perform async signalling */
- wake_up_interruptible (&tty->read_wait);
- if (n_hdlc->tty->fasync != NULL)
- kill_fasync (&n_hdlc->tty->fasync, SIGIO, POLL_IN);
- } /* end of n_hdlc_tty_receive() */
- /**
- * n_hdlc_tty_read - Called to retrieve one frame of data (if available)
- * @tty - pointer to tty instance data
- * @file - pointer to open file object
- * @buf - pointer to returned data buffer
- * @nr - size of returned data buffer
- *
- * Returns the number of bytes returned or error code.
- */
- static ssize_t n_hdlc_tty_read(struct tty_struct *tty, struct file *file,
- __u8 __user *buf, size_t nr)
- {
- struct n_hdlc *n_hdlc = tty2n_hdlc(tty);
- int ret = 0;
- struct n_hdlc_buf *rbuf;
- DECLARE_WAITQUEUE(wait, current);
- if (debuglevel >= DEBUG_LEVEL_INFO)
- printk("%s(%d)n_hdlc_tty_read() called\n",__FILE__,__LINE__);
-
- /* Validate the pointers */
- if (!n_hdlc)
- return -EIO;
- /* verify user access to buffer */
- if (!access_ok(buf, nr)) {
- printk(KERN_WARNING "%s(%d) n_hdlc_tty_read() can't verify user "
- "buffer\n", __FILE__, __LINE__);
- return -EFAULT;
- }
- add_wait_queue(&tty->read_wait, &wait);
- for (;;) {
- if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) {
- ret = -EIO;
- break;
- }
- if (tty_hung_up_p(file))
- break;
- set_current_state(TASK_INTERRUPTIBLE);
- rbuf = n_hdlc_buf_get(&n_hdlc->rx_buf_list);
- if (rbuf) {
- if (rbuf->count > nr) {
- /* too large for caller's buffer */
- ret = -EOVERFLOW;
- } else {
- __set_current_state(TASK_RUNNING);
- if (copy_to_user(buf, rbuf->buf, rbuf->count))
- ret = -EFAULT;
- else
- ret = rbuf->count;
- }
- if (n_hdlc->rx_free_buf_list.count >
- DEFAULT_RX_BUF_COUNT)
- kfree(rbuf);
- else
- n_hdlc_buf_put(&n_hdlc->rx_free_buf_list, rbuf);
- break;
- }
-
- /* no data */
- if (tty_io_nonblock(tty, file)) {
- ret = -EAGAIN;
- break;
- }
- schedule();
- if (signal_pending(current)) {
- ret = -EINTR;
- break;
- }
- }
- remove_wait_queue(&tty->read_wait, &wait);
- __set_current_state(TASK_RUNNING);
- return ret;
-
- } /* end of n_hdlc_tty_read() */
- /**
- * n_hdlc_tty_write - write a single frame of data to device
- * @tty - pointer to associated tty device instance data
- * @file - pointer to file object data
- * @data - pointer to transmit data (one frame)
- * @count - size of transmit frame in bytes
- *
- * Returns the number of bytes written (or error code).
- */
- static ssize_t n_hdlc_tty_write(struct tty_struct *tty, struct file *file,
- const unsigned char *data, size_t count)
- {
- struct n_hdlc *n_hdlc = tty2n_hdlc (tty);
- int error = 0;
- DECLARE_WAITQUEUE(wait, current);
- struct n_hdlc_buf *tbuf;
- if (debuglevel >= DEBUG_LEVEL_INFO)
- printk("%s(%d)n_hdlc_tty_write() called count=%zd\n",
- __FILE__,__LINE__,count);
-
- /* Verify pointers */
- if (!n_hdlc)
- return -EIO;
- if (n_hdlc->magic != HDLC_MAGIC)
- return -EIO;
- /* verify frame size */
- if (count > maxframe ) {
- if (debuglevel & DEBUG_LEVEL_INFO)
- printk (KERN_WARNING
- "n_hdlc_tty_write: truncating user packet "
- "from %lu to %d\n", (unsigned long) count,
- maxframe );
- count = maxframe;
- }
-
- add_wait_queue(&tty->write_wait, &wait);
- for (;;) {
- set_current_state(TASK_INTERRUPTIBLE);
-
- tbuf = n_hdlc_buf_get(&n_hdlc->tx_free_buf_list);
- if (tbuf)
- break;
- if (tty_io_nonblock(tty, file)) {
- error = -EAGAIN;
- break;
- }
- schedule();
-
- n_hdlc = tty2n_hdlc (tty);
- if (!n_hdlc || n_hdlc->magic != HDLC_MAGIC ||
- tty != n_hdlc->tty) {
- printk("n_hdlc_tty_write: %p invalid after wait!\n", n_hdlc);
- error = -EIO;
- break;
- }
-
- if (signal_pending(current)) {
- error = -EINTR;
- break;
- }
- }
- __set_current_state(TASK_RUNNING);
- remove_wait_queue(&tty->write_wait, &wait);
- if (!error) {
- /* Retrieve the user's buffer */
- memcpy(tbuf->buf, data, count);
- /* Send the data */
- tbuf->count = error = count;
- n_hdlc_buf_put(&n_hdlc->tx_buf_list,tbuf);
- n_hdlc_send_frames(n_hdlc,tty);
- }
- return error;
-
- } /* end of n_hdlc_tty_write() */
- /**
- * n_hdlc_tty_ioctl - process IOCTL system call for the tty device.
- * @tty - pointer to tty instance data
- * @file - pointer to open file object for device
- * @cmd - IOCTL command code
- * @arg - argument for IOCTL call (cmd dependent)
- *
- * Returns command dependent result.
- */
- static int n_hdlc_tty_ioctl(struct tty_struct *tty, struct file *file,
- unsigned int cmd, unsigned long arg)
- {
- struct n_hdlc *n_hdlc = tty2n_hdlc (tty);
- int error = 0;
- int count;
- unsigned long flags;
- struct n_hdlc_buf *buf = NULL;
- if (debuglevel >= DEBUG_LEVEL_INFO)
- printk("%s(%d)n_hdlc_tty_ioctl() called %d\n",
- __FILE__,__LINE__,cmd);
-
- /* Verify the status of the device */
- if (!n_hdlc || n_hdlc->magic != HDLC_MAGIC)
- return -EBADF;
- switch (cmd) {
- case FIONREAD:
- /* report count of read data available */
- /* in next available frame (if any) */
- spin_lock_irqsave(&n_hdlc->rx_buf_list.spinlock,flags);
- buf = list_first_entry_or_null(&n_hdlc->rx_buf_list.list,
- struct n_hdlc_buf, list_item);
- if (buf)
- count = buf->count;
- else
- count = 0;
- spin_unlock_irqrestore(&n_hdlc->rx_buf_list.spinlock,flags);
- error = put_user(count, (int __user *)arg);
- break;
- case TIOCOUTQ:
- /* get the pending tx byte count in the driver */
- count = tty_chars_in_buffer(tty);
- /* add size of next output frame in queue */
- spin_lock_irqsave(&n_hdlc->tx_buf_list.spinlock,flags);
- buf = list_first_entry_or_null(&n_hdlc->tx_buf_list.list,
- struct n_hdlc_buf, list_item);
- if (buf)
- count += buf->count;
- spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock,flags);
- error = put_user(count, (int __user *)arg);
- break;
- case TCFLSH:
- switch (arg) {
- case TCIOFLUSH:
- case TCOFLUSH:
- flush_tx_queue(tty);
- }
- /* fall through - to default */
- default:
- error = n_tty_ioctl_helper(tty, file, cmd, arg);
- break;
- }
- return error;
-
- } /* end of n_hdlc_tty_ioctl() */
- /**
- * n_hdlc_tty_poll - TTY callback for poll system call
- * @tty - pointer to tty instance data
- * @filp - pointer to open file object for device
- * @poll_table - wait queue for operations
- *
- * Determine which operations (read/write) will not block and return info
- * to caller.
- * Returns a bit mask containing info on which ops will not block.
- */
- static __poll_t n_hdlc_tty_poll(struct tty_struct *tty, struct file *filp,
- poll_table *wait)
- {
- struct n_hdlc *n_hdlc = tty2n_hdlc (tty);
- __poll_t mask = 0;
- if (debuglevel >= DEBUG_LEVEL_INFO)
- printk("%s(%d)n_hdlc_tty_poll() called\n",__FILE__,__LINE__);
-
- if (n_hdlc && n_hdlc->magic == HDLC_MAGIC && tty == n_hdlc->tty) {
- /* queue current process into any wait queue that */
- /* may awaken in the future (read and write) */
- poll_wait(filp, &tty->read_wait, wait);
- poll_wait(filp, &tty->write_wait, wait);
- /* set bits for operations that won't block */
- if (!list_empty(&n_hdlc->rx_buf_list.list))
- mask |= EPOLLIN | EPOLLRDNORM; /* readable */
- if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
- mask |= EPOLLHUP;
- if (tty_hung_up_p(filp))
- mask |= EPOLLHUP;
- if (!tty_is_writelocked(tty) &&
- !list_empty(&n_hdlc->tx_free_buf_list.list))
- mask |= EPOLLOUT | EPOLLWRNORM; /* writable */
- }
- return mask;
- } /* end of n_hdlc_tty_poll() */
- /**
- * n_hdlc_alloc - allocate an n_hdlc instance data structure
- *
- * Returns a pointer to newly created structure if success, otherwise %NULL
- */
- static struct n_hdlc *n_hdlc_alloc(void)
- {
- struct n_hdlc_buf *buf;
- int i;
- struct n_hdlc *n_hdlc = kzalloc(sizeof(*n_hdlc), GFP_KERNEL);
- if (!n_hdlc)
- return NULL;
- spin_lock_init(&n_hdlc->rx_free_buf_list.spinlock);
- spin_lock_init(&n_hdlc->tx_free_buf_list.spinlock);
- spin_lock_init(&n_hdlc->rx_buf_list.spinlock);
- spin_lock_init(&n_hdlc->tx_buf_list.spinlock);
- INIT_LIST_HEAD(&n_hdlc->rx_free_buf_list.list);
- INIT_LIST_HEAD(&n_hdlc->tx_free_buf_list.list);
- INIT_LIST_HEAD(&n_hdlc->rx_buf_list.list);
- INIT_LIST_HEAD(&n_hdlc->tx_buf_list.list);
- /* allocate free rx buffer list */
- for(i=0;i<DEFAULT_RX_BUF_COUNT;i++) {
- buf = kmalloc(N_HDLC_BUF_SIZE, GFP_KERNEL);
- if (buf)
- n_hdlc_buf_put(&n_hdlc->rx_free_buf_list,buf);
- else if (debuglevel >= DEBUG_LEVEL_INFO)
- printk("%s(%d)n_hdlc_alloc(), kalloc() failed for rx buffer %d\n",__FILE__,__LINE__, i);
- }
-
- /* allocate free tx buffer list */
- for(i=0;i<DEFAULT_TX_BUF_COUNT;i++) {
- buf = kmalloc(N_HDLC_BUF_SIZE, GFP_KERNEL);
- if (buf)
- n_hdlc_buf_put(&n_hdlc->tx_free_buf_list,buf);
- else if (debuglevel >= DEBUG_LEVEL_INFO)
- printk("%s(%d)n_hdlc_alloc(), kalloc() failed for tx buffer %d\n",__FILE__,__LINE__, i);
- }
-
- /* Initialize the control block */
- n_hdlc->magic = HDLC_MAGIC;
- n_hdlc->flags = 0;
-
- return n_hdlc;
-
- } /* end of n_hdlc_alloc() */
- /**
- * n_hdlc_buf_return - put the HDLC buffer after the head of the specified list
- * @buf_list - pointer to the buffer list
- * @buf - pointer to the buffer
- */
- static void n_hdlc_buf_return(struct n_hdlc_buf_list *buf_list,
- struct n_hdlc_buf *buf)
- {
- unsigned long flags;
- spin_lock_irqsave(&buf_list->spinlock, flags);
- list_add(&buf->list_item, &buf_list->list);
- buf_list->count++;
- spin_unlock_irqrestore(&buf_list->spinlock, flags);
- }
- /**
- * n_hdlc_buf_put - add specified HDLC buffer to tail of specified list
- * @buf_list - pointer to buffer list
- * @buf - pointer to buffer
- */
- static void n_hdlc_buf_put(struct n_hdlc_buf_list *buf_list,
- struct n_hdlc_buf *buf)
- {
- unsigned long flags;
- spin_lock_irqsave(&buf_list->spinlock, flags);
- list_add_tail(&buf->list_item, &buf_list->list);
- buf_list->count++;
- spin_unlock_irqrestore(&buf_list->spinlock, flags);
- } /* end of n_hdlc_buf_put() */
- /**
- * n_hdlc_buf_get - remove and return an HDLC buffer from list
- * @buf_list - pointer to HDLC buffer list
- *
- * Remove and return an HDLC buffer from the head of the specified HDLC buffer
- * list.
- * Returns a pointer to HDLC buffer if available, otherwise %NULL.
- */
- static struct n_hdlc_buf *n_hdlc_buf_get(struct n_hdlc_buf_list *buf_list)
- {
- unsigned long flags;
- struct n_hdlc_buf *buf;
- spin_lock_irqsave(&buf_list->spinlock, flags);
- buf = list_first_entry_or_null(&buf_list->list,
- struct n_hdlc_buf, list_item);
- if (buf) {
- list_del(&buf->list_item);
- buf_list->count--;
- }
- spin_unlock_irqrestore(&buf_list->spinlock, flags);
- return buf;
- } /* end of n_hdlc_buf_get() */
- static const char hdlc_banner[] __initconst =
- KERN_INFO "HDLC line discipline maxframe=%u\n";
- static const char hdlc_register_ok[] __initconst =
- KERN_INFO "N_HDLC line discipline registered.\n";
- static const char hdlc_register_fail[] __initconst =
- KERN_ERR "error registering line discipline: %d\n";
- static int __init n_hdlc_init(void)
- {
- int status;
- /* range check maxframe arg */
- if (maxframe < 4096)
- maxframe = 4096;
- else if (maxframe > 65535)
- maxframe = 65535;
- printk(hdlc_banner, maxframe);
- status = tty_register_ldisc(N_HDLC, &n_hdlc_ldisc);
- if (!status)
- printk(hdlc_register_ok);
- else
- printk(hdlc_register_fail, status);
- return status;
-
- } /* end of init_module() */
- #ifdef CONFIG_SPARC
- #undef __exitdata
- #define __exitdata
- #endif
- static const char hdlc_unregister_ok[] __exitdata =
- KERN_INFO "N_HDLC: line discipline unregistered\n";
- static const char hdlc_unregister_fail[] __exitdata =
- KERN_ERR "N_HDLC: can't unregister line discipline (err = %d)\n";
- static void __exit n_hdlc_exit(void)
- {
- /* Release tty registration of line discipline */
- int status = tty_unregister_ldisc(N_HDLC);
- if (status)
- printk(hdlc_unregister_fail, status);
- else
- printk(hdlc_unregister_ok);
- }
- module_init(n_hdlc_init);
- module_exit(n_hdlc_exit);
- MODULE_LICENSE("GPL");
- MODULE_AUTHOR("Paul Fulghum paulkf@microgate.com");
- module_param(debuglevel, int, 0);
- module_param(maxframe, int, 0);
- MODULE_ALIAS_LDISC(N_HDLC);
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