diff options
Diffstat (limited to 'drivers/tty/n_hdlc.c')
| -rw-r--r-- | drivers/tty/n_hdlc.c | 1007 |
1 files changed, 1007 insertions, 0 deletions
diff --git a/drivers/tty/n_hdlc.c b/drivers/tty/n_hdlc.c new file mode 100644 index 00000000000..47d32281032 --- /dev/null +++ b/drivers/tty/n_hdlc.c @@ -0,0 +1,1007 @@ +/* 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/smp_lock.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/system.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 */ + tty->flags |= (1 << TTY_DO_WRITE_WAKEUP); + 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) + tty->flags &= ~(1 << TTY_DO_WRITE_WAKEUP); + + /* 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) { + tty->flags &= ~(1 << TTY_DO_WRITE_WAKEUP); + 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; + struct n_hdlc_buf *rbuf; + + 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; + } + + tty_lock(); + + for (;;) { + if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) { + tty_unlock(); + return -EIO; + } + + n_hdlc = tty2n_hdlc (tty); + if (!n_hdlc || n_hdlc->magic != HDLC_MAGIC || + tty != n_hdlc->tty) { + tty_unlock(); + return 0; + } + + rbuf = n_hdlc_buf_get(&n_hdlc->rx_buf_list); + if (rbuf) + break; + + /* no data */ + if (file->f_flags & O_NONBLOCK) { + tty_unlock(); + return -EAGAIN; + } + + interruptible_sleep_on (&tty->read_wait); + if (signal_pending(current)) { + tty_unlock(); + return -EINTR; + } + } + + if (rbuf->count > nr) + /* frame too large for caller's buffer (discard frame) */ + ret = -EOVERFLOW; + else { + /* Copy the data to the caller's buffer */ + if (copy_to_user(buf, rbuf->buf, rbuf->count)) + ret = -EFAULT; + else + ret = rbuf->count; + } + + /* return HDLC buffer to free list unless the free list */ + /* count has exceeded the default value, in which case the */ + /* buffer is freed back to the OS to conserve memory */ + 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); + tty_unlock(); + 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; + } + + tty_lock(); + + add_wait_queue(&tty->write_wait, &wait); + set_current_state(TASK_INTERRUPTIBLE); + + /* Allocate transmit buffer */ + /* sleep until transmit buffer available */ + while (!(tbuf = n_hdlc_buf_get(&n_hdlc->tx_free_buf_list))) { + 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); + } + tty_unlock(); + 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_CLOSED, &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 = kmalloc(sizeof(*n_hdlc), GFP_KERNEL); + + if (!n_hdlc) + return NULL; + + memset(n_hdlc, 0, sizeof(*n_hdlc)); + + 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 char hdlc_init_fail[] __initdata = + KERN_INFO "N_HDLC: init failure %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); + + if (status) + printk(hdlc_init_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); |