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836 lines
22 KiB
836 lines
22 KiB
// SPDX-License-Identifier: GPL-1.0+ |
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/* generic HDLC line discipline for Linux |
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* |
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* Written by Paul Fulghum [email protected] |
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* for Microgate Corporation |
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* |
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* Microgate and SyncLink are registered trademarks of Microgate Corporation |
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* |
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* Adapted from ppp.c, written by Michael Callahan <[email protected]>, |
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* Al Longyear <[email protected]>, |
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* Paul Mackerras <[email protected]> |
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* |
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* Original release 01/11/99 |
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* |
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* 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. |
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* |
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* All HDLC data is frame oriented which means: |
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* |
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* 1. tty write calls represent one complete transmit frame of data |
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* The device driver should accept the complete frame or none of |
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* 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 |
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* 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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* |
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* |
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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. |
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* |
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* The HDLC line discipline queues the receive frames in separate |
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* buffers so complete receive frames can be returned by the |
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* tty read calls. |
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* |
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* 3. tty read calls returns an entire frame of data or nothing. |
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* |
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* 4. all send and receive data is considered raw. No processing |
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* or translation is performed by the line discipline, regardless |
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* of the tty flags |
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* |
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* 5. When line discipline is queried for the amount of receive |
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* data available (FIOC), 0 is returned if no data available, |
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* 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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* |
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* These conventions allow the standard tty programming interface |
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* to be used for synchronous HDLC applications when used with |
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* this line discipline (or another line discipline that is frame |
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* oriented such as N_PPP). |
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* |
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* The SyncLink driver (synclink.c) implements both asynchronous |
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* (using standard line discipline N_TTY) and synchronous HDLC |
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* (using N_HDLC) communications, with the latter using the above |
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* conventions. |
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* |
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* This implementation is very basic and does not maintain |
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* any statistics. The main point is to enforce the raw data |
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* and frame orientation of HDLC communications. |
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* |
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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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*/ |
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|
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#define HDLC_MAGIC 0x239e |
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|
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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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|
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#include <linux/poll.h> |
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#include <linux/in.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/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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|
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#include <asm/termios.h> |
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#include <linux/uaccess.h> |
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#include "tty.h" |
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|
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/* |
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* Buffers for individual HDLC frames |
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*/ |
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#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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|
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struct n_hdlc_buf { |
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struct list_head list_item; |
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int count; |
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char buf[]; |
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}; |
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|
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struct n_hdlc_buf_list { |
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struct list_head list; |
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int count; |
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spinlock_t spinlock; |
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}; |
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|
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/** |
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* struct n_hdlc - per device instance data structure |
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* @magic: magic value for structure |
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* @tbusy: reentrancy flag for tx wakeup code |
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* @woke_up: tx wakeup needs to be run again as it was called while @tbusy |
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* @tx_buf_list: list of pending transmit frame buffers |
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* @rx_buf_list: list of received frame buffers |
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* @tx_free_buf_list: list unused transmit frame buffers |
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* @rx_free_buf_list: list unused received frame buffers |
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*/ |
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struct n_hdlc { |
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int magic; |
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bool tbusy; |
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bool woke_up; |
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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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}; |
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|
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/* |
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* HDLC buffer list manipulation functions |
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*/ |
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static void n_hdlc_buf_return(struct n_hdlc_buf_list *buf_list, |
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struct n_hdlc_buf *buf); |
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static void n_hdlc_buf_put(struct n_hdlc_buf_list *list, |
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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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|
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/* Local functions */ |
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|
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static struct n_hdlc *n_hdlc_alloc(void); |
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|
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/* max frame size for memory allocations */ |
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static int maxframe = 4096; |
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|
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static void flush_rx_queue(struct tty_struct *tty) |
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{ |
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struct n_hdlc *n_hdlc = tty->disc_data; |
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struct n_hdlc_buf *buf; |
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|
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while ((buf = n_hdlc_buf_get(&n_hdlc->rx_buf_list))) |
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n_hdlc_buf_put(&n_hdlc->rx_free_buf_list, buf); |
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} |
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|
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static void flush_tx_queue(struct tty_struct *tty) |
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{ |
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struct n_hdlc *n_hdlc = tty->disc_data; |
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struct n_hdlc_buf *buf; |
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|
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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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} |
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|
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static void n_hdlc_free_buf_list(struct n_hdlc_buf_list *list) |
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{ |
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struct n_hdlc_buf *buf; |
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|
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do { |
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buf = n_hdlc_buf_get(list); |
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kfree(buf); |
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} while (buf); |
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} |
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|
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/** |
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* n_hdlc_tty_close - line discipline close |
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* @tty: pointer to tty info structure |
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* |
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* Called when the line discipline is changed to something |
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* else, the tty is closed, or the tty detects a hangup. |
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*/ |
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static void n_hdlc_tty_close(struct tty_struct *tty) |
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{ |
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struct n_hdlc *n_hdlc = tty->disc_data; |
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|
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if (n_hdlc->magic != HDLC_MAGIC) { |
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pr_warn("n_hdlc: trying to close unopened tty!\n"); |
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return; |
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} |
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#if defined(TTY_NO_WRITE_SPLIT) |
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clear_bit(TTY_NO_WRITE_SPLIT, &tty->flags); |
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#endif |
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tty->disc_data = NULL; |
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|
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/* Ensure that the n_hdlcd process is not hanging on select()/poll() */ |
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wake_up_interruptible(&tty->read_wait); |
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wake_up_interruptible(&tty->write_wait); |
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|
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n_hdlc_free_buf_list(&n_hdlc->rx_free_buf_list); |
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n_hdlc_free_buf_list(&n_hdlc->tx_free_buf_list); |
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n_hdlc_free_buf_list(&n_hdlc->rx_buf_list); |
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n_hdlc_free_buf_list(&n_hdlc->tx_buf_list); |
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kfree(n_hdlc); |
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} /* end of n_hdlc_tty_close() */ |
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|
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/** |
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* n_hdlc_tty_open - called when line discipline changed to n_hdlc |
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* @tty: pointer to tty info structure |
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* |
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* Returns 0 if success, otherwise error code |
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*/ |
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static int n_hdlc_tty_open(struct tty_struct *tty) |
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{ |
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struct n_hdlc *n_hdlc = tty->disc_data; |
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|
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pr_debug("%s() called (device=%s)\n", __func__, tty->name); |
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|
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/* There should not be an existing table for this slot. */ |
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if (n_hdlc) { |
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pr_err("%s: tty already associated!\n", __func__); |
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return -EEXIST; |
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} |
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n_hdlc = n_hdlc_alloc(); |
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if (!n_hdlc) { |
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pr_err("%s: n_hdlc_alloc failed\n", __func__); |
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return -ENFILE; |
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} |
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tty->disc_data = n_hdlc; |
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tty->receive_room = 65536; |
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|
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/* change tty_io write() to not split large writes into 8K chunks */ |
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set_bit(TTY_NO_WRITE_SPLIT, &tty->flags); |
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|
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/* flush receive data from driver */ |
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tty_driver_flush_buffer(tty); |
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|
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return 0; |
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|
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} /* end of n_tty_hdlc_open() */ |
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|
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/** |
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* n_hdlc_send_frames - send frames on pending send buffer list |
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* @n_hdlc: pointer to ldisc instance data |
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* @tty: pointer to tty instance data |
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* |
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* Send frames on pending send buffer list until the driver does not accept a |
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* frame (busy) this function is called after adding a frame to the send buffer |
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* list and by the tty wakeup callback. |
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*/ |
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static void n_hdlc_send_frames(struct n_hdlc *n_hdlc, struct tty_struct *tty) |
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{ |
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register int actual; |
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unsigned long flags; |
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struct n_hdlc_buf *tbuf; |
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check_again: |
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|
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spin_lock_irqsave(&n_hdlc->tx_buf_list.spinlock, flags); |
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if (n_hdlc->tbusy) { |
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n_hdlc->woke_up = true; |
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spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags); |
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return; |
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} |
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n_hdlc->tbusy = true; |
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n_hdlc->woke_up = false; |
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spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags); |
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tbuf = n_hdlc_buf_get(&n_hdlc->tx_buf_list); |
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while (tbuf) { |
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pr_debug("sending frame %p, count=%d\n", tbuf, tbuf->count); |
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|
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/* Send the next block of data to device */ |
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set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); |
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actual = tty->ops->write(tty, tbuf->buf, tbuf->count); |
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|
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/* rollback was possible and has been done */ |
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if (actual == -ERESTARTSYS) { |
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n_hdlc_buf_return(&n_hdlc->tx_buf_list, tbuf); |
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break; |
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} |
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/* if transmit error, throw frame away by */ |
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/* pretending it was accepted by driver */ |
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if (actual < 0) |
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actual = tbuf->count; |
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|
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if (actual == tbuf->count) { |
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pr_debug("frame %p completed\n", tbuf); |
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|
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/* free current transmit buffer */ |
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n_hdlc_buf_put(&n_hdlc->tx_free_buf_list, tbuf); |
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|
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/* wait up sleeping writers */ |
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wake_up_interruptible(&tty->write_wait); |
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|
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/* get next pending transmit buffer */ |
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tbuf = n_hdlc_buf_get(&n_hdlc->tx_buf_list); |
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} else { |
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pr_debug("frame %p pending\n", tbuf); |
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|
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/* |
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* the buffer was not accepted by driver, |
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* return it back into tx queue |
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*/ |
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n_hdlc_buf_return(&n_hdlc->tx_buf_list, tbuf); |
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break; |
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} |
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} |
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if (!tbuf) |
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clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); |
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|
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/* Clear the re-entry flag */ |
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spin_lock_irqsave(&n_hdlc->tx_buf_list.spinlock, flags); |
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n_hdlc->tbusy = false; |
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spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags); |
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|
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if (n_hdlc->woke_up) |
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goto check_again; |
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} /* end of n_hdlc_send_frames() */ |
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|
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/** |
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* n_hdlc_tty_wakeup - Callback for transmit wakeup |
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* @tty: pointer to associated tty instance data |
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* |
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* Called when low level device driver can accept more send data. |
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*/ |
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static void n_hdlc_tty_wakeup(struct tty_struct *tty) |
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{ |
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struct n_hdlc *n_hdlc = tty->disc_data; |
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|
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n_hdlc_send_frames(n_hdlc, tty); |
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} /* end of n_hdlc_tty_wakeup() */ |
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|
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/** |
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* n_hdlc_tty_receive - Called by tty driver when receive data is available |
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* @tty: pointer to tty instance data |
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* @data: pointer to received data |
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* @flags: pointer to flags for data |
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* @count: count of received data in bytes |
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* |
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* Called by tty low level driver when receive data is available. Data is |
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* interpreted as one HDLC frame. |
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*/ |
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static void n_hdlc_tty_receive(struct tty_struct *tty, const __u8 *data, |
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const char *flags, int count) |
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{ |
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register struct n_hdlc *n_hdlc = tty->disc_data; |
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register struct n_hdlc_buf *buf; |
|
|
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pr_debug("%s() called count=%d\n", __func__, count); |
|
|
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/* verify line is using HDLC discipline */ |
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if (n_hdlc->magic != HDLC_MAGIC) { |
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pr_err("line not using HDLC discipline\n"); |
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return; |
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} |
|
|
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if (count > maxframe) { |
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pr_debug("rx count>maxframesize, data discarded\n"); |
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return; |
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} |
|
|
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/* get a free HDLC buffer */ |
|
buf = n_hdlc_buf_get(&n_hdlc->rx_free_buf_list); |
|
if (!buf) { |
|
/* |
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* no buffers in free list, attempt to allocate another rx |
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* buffer unless the maximum count has been reached |
|
*/ |
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if (n_hdlc->rx_buf_list.count < MAX_RX_BUF_COUNT) |
|
buf = kmalloc(struct_size(buf, buf, maxframe), |
|
GFP_ATOMIC); |
|
} |
|
|
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if (!buf) { |
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pr_debug("no more rx buffers, data discarded\n"); |
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return; |
|
} |
|
|
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/* copy received data to HDLC buffer */ |
|
memcpy(buf->buf, data, count); |
|
buf->count = count; |
|
|
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/* add HDLC buffer to list of received frames */ |
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n_hdlc_buf_put(&n_hdlc->rx_buf_list, buf); |
|
|
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/* wake up any blocked reads and perform async signalling */ |
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wake_up_interruptible(&tty->read_wait); |
|
if (tty->fasync != NULL) |
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kill_fasync(&tty->fasync, SIGIO, POLL_IN); |
|
|
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} /* end of n_hdlc_tty_receive() */ |
|
|
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/** |
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* 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 |
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* @kbuf: pointer to returned data buffer |
|
* @nr: size of returned data buffer |
|
* @cookie: stored rbuf from previous run |
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* @offset: offset into the data buffer |
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* |
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* Returns the number of bytes returned or error code. |
|
*/ |
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static ssize_t n_hdlc_tty_read(struct tty_struct *tty, struct file *file, |
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__u8 *kbuf, size_t nr, |
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void **cookie, unsigned long offset) |
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{ |
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struct n_hdlc *n_hdlc = tty->disc_data; |
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int ret = 0; |
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struct n_hdlc_buf *rbuf; |
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DECLARE_WAITQUEUE(wait, current); |
|
|
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/* Is this a repeated call for an rbuf we already found earlier? */ |
|
rbuf = *cookie; |
|
if (rbuf) |
|
goto have_rbuf; |
|
|
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add_wait_queue(&tty->read_wait, &wait); |
|
|
|
for (;;) { |
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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) |
|
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); |
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__set_current_state(TASK_RUNNING); |
|
|
|
if (!rbuf) |
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return ret; |
|
*cookie = rbuf; |
|
|
|
have_rbuf: |
|
/* Have we used it up entirely? */ |
|
if (offset >= rbuf->count) |
|
goto done_with_rbuf; |
|
|
|
/* More data to go, but can't copy any more? EOVERFLOW */ |
|
ret = -EOVERFLOW; |
|
if (!nr) |
|
goto done_with_rbuf; |
|
|
|
/* Copy as much data as possible */ |
|
ret = rbuf->count - offset; |
|
if (ret > nr) |
|
ret = nr; |
|
memcpy(kbuf, rbuf->buf+offset, ret); |
|
offset += ret; |
|
|
|
/* If we still have data left, we leave the rbuf in the cookie */ |
|
if (offset < rbuf->count) |
|
return ret; |
|
|
|
done_with_rbuf: |
|
*cookie = NULL; |
|
|
|
if (n_hdlc->rx_free_buf_list.count > DEFAULT_RX_BUF_COUNT) |
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kfree(rbuf); |
|
else |
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n_hdlc_buf_put(&n_hdlc->rx_free_buf_list, rbuf); |
|
|
|
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 = tty->disc_data; |
|
int error = 0; |
|
DECLARE_WAITQUEUE(wait, current); |
|
struct n_hdlc_buf *tbuf; |
|
|
|
pr_debug("%s() called count=%zd\n", __func__, count); |
|
|
|
if (n_hdlc->magic != HDLC_MAGIC) |
|
return -EIO; |
|
|
|
/* verify frame size */ |
|
if (count > maxframe) { |
|
pr_debug("%s: truncating user packet from %zu to %d\n", |
|
__func__, 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(); |
|
|
|
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 = tty->disc_data; |
|
int error = 0; |
|
int count; |
|
unsigned long flags; |
|
struct n_hdlc_buf *buf = NULL; |
|
|
|
pr_debug("%s() called %d\n", __func__, cmd); |
|
|
|
/* Verify the status of the device */ |
|
if (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); |
|
} |
|
fallthrough; /* 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 |
|
* @wait: 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 = tty->disc_data; |
|
__poll_t mask = 0; |
|
|
|
if (n_hdlc->magic != HDLC_MAGIC) |
|
return 0; |
|
|
|
/* |
|
* queue the 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() */ |
|
|
|
static void n_hdlc_alloc_buf(struct n_hdlc_buf_list *list, unsigned int count, |
|
const char *name) |
|
{ |
|
struct n_hdlc_buf *buf; |
|
unsigned int i; |
|
|
|
for (i = 0; i < count; i++) { |
|
buf = kmalloc(struct_size(buf, buf, maxframe), GFP_KERNEL); |
|
if (!buf) { |
|
pr_debug("%s(), kmalloc() failed for %s buffer %u\n", |
|
__func__, name, i); |
|
return; |
|
} |
|
n_hdlc_buf_put(list, buf); |
|
} |
|
} |
|
|
|
/** |
|
* 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 *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); |
|
|
|
n_hdlc_alloc_buf(&n_hdlc->rx_free_buf_list, DEFAULT_RX_BUF_COUNT, "rx"); |
|
n_hdlc_alloc_buf(&n_hdlc->tx_free_buf_list, DEFAULT_TX_BUF_COUNT, "tx"); |
|
|
|
/* Initialize the control block */ |
|
n_hdlc->magic = HDLC_MAGIC; |
|
|
|
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 struct tty_ldisc_ops n_hdlc_ldisc = { |
|
.owner = THIS_MODULE, |
|
.num = N_HDLC, |
|
.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, |
|
}; |
|
|
|
static int __init n_hdlc_init(void) |
|
{ |
|
int status; |
|
|
|
/* range check maxframe arg */ |
|
maxframe = clamp(maxframe, 4096, MAX_HDLC_FRAME_SIZE); |
|
|
|
status = tty_register_ldisc(&n_hdlc_ldisc); |
|
if (!status) |
|
pr_info("N_HDLC line discipline registered with maxframe=%d\n", |
|
maxframe); |
|
else |
|
pr_err("N_HDLC: error registering line discipline: %d\n", |
|
status); |
|
|
|
return status; |
|
|
|
} /* end of init_module() */ |
|
|
|
static void __exit n_hdlc_exit(void) |
|
{ |
|
tty_unregister_ldisc(&n_hdlc_ldisc); |
|
} |
|
|
|
module_init(n_hdlc_init); |
|
module_exit(n_hdlc_exit); |
|
|
|
MODULE_LICENSE("GPL"); |
|
MODULE_AUTHOR("Paul Fulghum [email protected]"); |
|
module_param(maxframe, int, 0); |
|
MODULE_ALIAS_LDISC(N_HDLC);
|
|
|