--- /dev/null
+/* 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 code is released under the GNU General Public License (GPL)
+ *
+ * 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 <asm/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 n_hdlc_buf *link;
+ int count;
+ char buf[1];
+};
+
+#define N_HDLC_BUF_SIZE (sizeof(struct n_hdlc_buf) + maxframe)
+
+struct n_hdlc_buf_list {
+ struct n_hdlc_buf *head;
+ struct n_hdlc_buf *tail;
+ 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
+ * @tbuf - currently transmitting tx buffer
+ * @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 *tbuf;
+ 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_list_init(struct n_hdlc_buf_list *list);
+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 unsigned int 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;
+ unsigned long flags;
+
+ while ((buf = n_hdlc_buf_get(&n_hdlc->tx_buf_list)))
+ n_hdlc_buf_put(&n_hdlc->tx_free_buf_list, buf);
+ spin_lock_irqsave(&n_hdlc->tx_buf_list.spinlock, flags);
+ if (n_hdlc->tbuf) {
+ n_hdlc_buf_put(&n_hdlc->tx_free_buf_list, n_hdlc->tbuf);
+ n_hdlc->tbuf = NULL;
+ }
+ spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags);
+}
+
+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->tbuf);
+ 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);
+
+ /* get current transmit buffer or get new transmit */
+ /* buffer from list of pending transmit buffers */
+
+ tbuf = n_hdlc->tbuf;
+ if (!tbuf)
+ 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->tbuf = 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);
+
+ /* this tx buffer is done */
+ n_hdlc->tbuf = NULL;
+
+ /* 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);
+
+ /* buffer not accepted by driver */
+ /* set this buffer as pending buffer */
+ n_hdlc->tbuf = 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(VERIFY_WRITE, 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_DONE, &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 {
+ 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 (file->f_flags & O_NONBLOCK) {
+ 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 (file->f_flags & O_NONBLOCK) {
+ 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;
+
+ 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);
+ if (n_hdlc->rx_buf_list.head)
+ count = n_hdlc->rx_buf_list.head->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);
+ if (n_hdlc->tx_buf_list.head)
+ count += n_hdlc->tx_buf_list.head->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 unsigned int n_hdlc_tty_poll(struct tty_struct *tty, struct file *filp,
+ poll_table *wait)
+{
+ struct n_hdlc *n_hdlc = tty2n_hdlc (tty);
+ unsigned int 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 (n_hdlc->rx_buf_list.head)
+ mask |= POLLIN | POLLRDNORM; /* readable */
+ if (test_bit(TTY_OTHER_DONE, &tty->flags))
+ mask |= POLLHUP;
+ if (tty_hung_up_p(filp))
+ mask |= POLLHUP;
+ if (!tty_is_writelocked(tty) &&
+ n_hdlc->tx_free_buf_list.head)
+ mask |= POLLOUT | POLLWRNORM; /* 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;
+
+ n_hdlc_buf_list_init(&n_hdlc->rx_free_buf_list);
+ n_hdlc_buf_list_init(&n_hdlc->tx_free_buf_list);
+ n_hdlc_buf_list_init(&n_hdlc->rx_buf_list);
+ n_hdlc_buf_list_init(&n_hdlc->tx_buf_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_list_init - initialize specified HDLC buffer list
+ * @list - pointer to buffer list
+ */
+static void n_hdlc_buf_list_init(struct n_hdlc_buf_list *list)
+{
+ memset(list, 0, sizeof(*list));
+ spin_lock_init(&list->spinlock);
+} /* end of n_hdlc_buf_list_init() */
+
+/**
+ * n_hdlc_buf_put - add specified HDLC buffer to tail of specified list
+ * @list - pointer to buffer list
+ * @buf - pointer to buffer
+ */
+static void n_hdlc_buf_put(struct n_hdlc_buf_list *list,
+ struct n_hdlc_buf *buf)
+{
+ unsigned long flags;
+ spin_lock_irqsave(&list->spinlock,flags);
+
+ buf->link=NULL;
+ if (list->tail)
+ list->tail->link = buf;
+ else
+ list->head = buf;
+ list->tail = buf;
+ (list->count)++;
+
+ spin_unlock_irqrestore(&list->spinlock,flags);
+
+} /* end of n_hdlc_buf_put() */
+
+/**
+ * n_hdlc_buf_get - remove and return an HDLC buffer from list
+ * @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 *list)
+{
+ unsigned long flags;
+ struct n_hdlc_buf *buf;
+ spin_lock_irqsave(&list->spinlock,flags);
+
+ buf = list->head;
+ if (buf) {
+ list->head = buf->link;
+ (list->count)--;
+ }
+ if (!list->head)
+ list->tail = NULL;
+
+ spin_unlock_irqrestore(&list->spinlock,flags);
+ return buf;
+
+} /* end of n_hdlc_buf_get() */
+
+static char hdlc_banner[] __initdata =
+ KERN_INFO "HDLC line discipline maxframe=%u\n";
+static char hdlc_register_ok[] __initdata =
+ KERN_INFO "N_HDLC line discipline registered.\n";
+static char hdlc_register_fail[] __initdata =
+ 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() */
+
+static char hdlc_unregister_ok[] __exitdata =
+ KERN_INFO "N_HDLC: line discipline unregistered\n";
+static 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);
Code Review / kvmfornfv.git / blobdiff