/*
- * UniPi PLC device driver - Copyright (C) 2018 UniPi Technology
- * Author: Tomas Knot <tomasknot@gmail.com>
+ * Implements line discpline for using with Neuron/Axon.
*
- * Based on the SC16IS7xx driver by Jon Ringle <jringle@gridpoint.com>,
- * which was in turn based on max310x.c, by Alexander Shiyan <shc_work@mail.ru>
+ * Derivated from n_tty.c --- implements the N_TTY line discipline.
*
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
+ * This code used to be in tty_io.c, but things are getting hairy
+ * enough that it made sense to split things off. (The N_TTY
+ * processing has changed so much that it's hardly recognizable,
+ * anyway...)
*
+ * Note that the open routine for N_TTY is guaranteed never to return
+ * an error. This is because Linux will fall back to setting a line
+ * to N_TTY if it can not switch to any other line discipline.
+ *
+ * Written by Theodore Ts'o, Copyright 1994.
+ *
+ * This file also contains code originally written by Linus Torvalds,
+ * Copyright 1991, 1992, 1993, and by Julian Cowley, Copyright 1994.
+ *
+ * This file may be redistributed under the terms of the GNU General Public
+ * License.
+ *
+ * Reduced memory usage for older ARM systems - Russell King.
+ *
+ * 2000/01/20 Fixed SMP locking on put_tty_queue using bits of
+ * the patch by Andrew J. Kroll <ag784@freenet.buffalo.edu>
+ * who actually finally proved there really was a race.
+ *
+ * 2002/03/18 Implemented unipi_tty_wakeup to send SIGIO POLL_OUTs to
+ * waiting writing processes-Sapan Bhatia <sapan@corewars.org>.
+ * Also fixed a bug in BLOCKING mode where unipi_tty_write returns
+ * EAGAIN
*/
-#include "unipi_tty.h"
+#include <linux/types.h>
+#include <linux/major.h>
+#include <linux/errno.h>
+#include <linux/signal.h>
+#include <linux/fcntl.h>
+#include <linux/sched.h>
#include <linux/interrupt.h>
#include <linux/tty.h>
#include <linux/timer.h>
#include <linux/ctype.h>
#include <linux/mm.h>
#include <linux/string.h>
+#include <linux/slab.h>
+#include <linux/poll.h>
+#include <linux/bitops.h>
+#include <linux/audit.h>
+#include <linux/file.h>
+#include <linux/uaccess.h>
+#include <linux/module.h>
+#include <linux/ratelimit.h>
+#include <linux/vmalloc.h>
+
+#include "unipi_tty.h"
+
+/* number of characters left in xmit buffer before select has we have room */
+#define WAKEUP_CHARS 256
+
+/*
+ * This defines the low- and high-watermarks for throttling and
+ * unthrottling the TTY driver. These watermarks are used for
+ * controlling the space in the read buffer.
+ */
+#define TTY_THRESHOLD_THROTTLE 128 /* now based on remaining room */
+#define TTY_THRESHOLD_UNTHROTTLE 128
+
+
+// #undef UNIPI_TTY_TRACE
+#ifdef NEURONSPI_DETAILED_DEBUG
+# define unipi_tty_trace(f, args...) trace_printk(f, ##args)
+#else
+# define unipi_tty_trace(f, args...)
+#endif
+
+struct unipi_tty_data {
+ /* producer-published */
+ size_t read_head;
+ size_t commit_head;
+ //DECLARE_BITMAP(char_map, 256);
-struct tty_ldisc_ops neuronspi_tty_ldisc;
+ /* private to unipi_tty_receive_overrun (single-threaded) */
+ /* non-atomic */
+ bool no_room;
-int neuronspi_tty_init()
+ /* shared by producer and consumer */
+ char read_buf[N_TTY_BUF_SIZE];
+
+ /* consumer-published */
+ size_t read_tail;
+
+
+ struct mutex atomic_read_lock;
+ struct mutex output_lock;
+};
+
+static inline size_t read_cnt(struct unipi_tty_data *ldata)
{
- int err;
-#if NEURONSPI_DETAILED_DEBUG > 0
- printk(KERN_INFO "UNIPISPI: TTY Init\n");
+ return ldata->read_head - ldata->read_tail;
+}
+
+static inline unsigned char read_buf(struct unipi_tty_data *ldata, size_t i)
+{
+ return ldata->read_buf[i & (N_TTY_BUF_SIZE - 1)];
+}
+
+static inline unsigned char *read_buf_addr(struct unipi_tty_data *ldata, size_t i)
+{
+ return &ldata->read_buf[i & (N_TTY_BUF_SIZE - 1)];
+}
+
+
+/**
+ * tty_throttle_safe - flow control
+ * @tty: terminal
+ *
+ * Similar to tty_throttle() but will only attempt throttle
+ * if tty->flow_change is TTY_THROTTLE_SAFE. Prevents an accidental
+ * throttle due to race conditions when throttling is conditional
+ * on factors evaluated prior to throttling.
+ *
+ * Returns 0 if tty is throttled (or was already throttled)
+ */
+
+int unipi_tty_throttle_safe(struct tty_struct *tty)
+{
+ int ret = 0;
+
+ mutex_lock(&tty->throttle_mutex);
+ if (!tty_throttled(tty)) {
+ if (tty->flow_change != TTY_THROTTLE_SAFE)
+ ret = 1;
+ else {
+ set_bit(TTY_THROTTLED, &tty->flags);
+ if (tty->ops->throttle)
+ tty->ops->throttle(tty);
+ }
+ }
+ mutex_unlock(&tty->throttle_mutex);
+
+ return ret;
+}
+
+/**
+ * tty_unthrottle_safe - flow control
+ * @tty: terminal
+ *
+ * Similar to tty_unthrottle() but will only attempt unthrottle
+ * if tty->flow_change is TTY_UNTHROTTLE_SAFE. Prevents an accidental
+ * unthrottle due to race conditions when unthrottling is conditional
+ * on factors evaluated prior to unthrottling.
+ *
+ * Returns 0 if tty is unthrottled (or was already unthrottled)
+ */
+
+int unipi_tty_unthrottle_safe(struct tty_struct *tty)
+{
+ int ret = 0;
+
+ mutex_lock(&tty->throttle_mutex);
+ if (tty_throttled(tty)) {
+ if (tty->flow_change != TTY_UNTHROTTLE_SAFE)
+ ret = 1;
+ else {
+ clear_bit(TTY_THROTTLED, &tty->flags);
+ if (tty->ops->unthrottle)
+ tty->ops->unthrottle(tty);
+ }
+ }
+ mutex_unlock(&tty->throttle_mutex);
+
+ return ret;
+}
+
+
+/**
+ * unipi_tty_kick_worker - start input worker (if required)
+ * @tty: terminal
+ *
+ * Re-schedules the flip buffer work if it may have stopped
+ *
+ * Caller holds exclusive termios_rwsem
+ * or
+ * unipi_tty_read()/consumer path:
+ * holds non-exclusive termios_rwsem
+ */
+
+static void unipi_tty_kick_worker(struct tty_struct *tty)
+{
+ struct unipi_tty_data *ldata = tty->disc_data;
+ struct tty_port *port = tty->port;
+
+ /* Did the input worker stop? Restart it */
+ if (unlikely(ldata->no_room)) {
+ ldata->no_room = 0;
+
+ WARN_RATELIMIT(tty->port->itty == NULL,
+ "scheduling with invalid itty\n");
+ /* see if ldisc has been killed - if so, this means that
+ * even though the ldisc has been halted and ->buf.work
+ * cancelled, ->buf.work is about to be rescheduled
+ */
+ WARN_RATELIMIT(test_bit(TTY_LDISC_HALTED, &tty->flags),
+ "scheduling buffer work for halted ldisc\n");
+ //tty_buffer_restart_work(tty->port);
+ queue_work(system_unbound_wq, &port->buf.work);
+ }
+}
+
+static ssize_t chars_in_buffer(struct tty_struct *tty)
+{
+ struct unipi_tty_data *ldata = tty->disc_data;
+ ssize_t n = 0;
+
+ n = ldata->commit_head - ldata->read_tail;
+ return n;
+}
+
+/**
+ * unipi_tty_write_wakeup - asynchronous I/O notifier
+ * @tty: tty device
+ *
+ * Required for the ptys, serial driver etc. since processes
+ * that attach themselves to the master and rely on ASYNC
+ * IO must be woken up
+ */
+
+static void unipi_tty_write_wakeup(struct tty_struct *tty)
+{
+ unipi_tty_trace(KERN_INFO "UNIPI_LDISC: Wakeup start.");
+
+ clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
+ kill_fasync(&tty->fasync, SIGIO, POLL_OUT);
+}
+
+static void unipi_tty_check_throttle(struct tty_struct *tty)
+{
+ struct unipi_tty_data *ldata = tty->disc_data;
+
+ /*
+ * Check the remaining room for the input canonicalization
+ * mode. We don't want to throttle the driver if we're in
+ * canonical mode and don't have a newline yet!
+ */
+
+ while (1) {
+ int throttled;
+ tty_set_flow_change(tty, TTY_THROTTLE_SAFE);
+ if (N_TTY_BUF_SIZE - read_cnt(ldata) >= TTY_THRESHOLD_THROTTLE)
+ break;
+ throttled = unipi_tty_throttle_safe(tty);
+ if (!throttled)
+ break;
+ }
+ __tty_set_flow_change(tty, 0);
+}
+
+static void unipi_tty_check_unthrottle(struct tty_struct *tty)
+{
+ if (tty->driver->type == TTY_DRIVER_TYPE_PTY) {
+ if (chars_in_buffer(tty) > TTY_THRESHOLD_UNTHROTTLE)
+ return;
+ unipi_tty_kick_worker(tty);
+ tty_wakeup(tty->link);
+ return;
+ }
+
+ /* If there is enough space in the read buffer now, let the
+ * low-level driver know. We use chars_in_buffer() to
+ * check the buffer, as it now knows about canonical mode.
+ * Otherwise, if the driver is throttled and the line is
+ * longer than TTY_THRESHOLD_UNTHROTTLE in canonical mode,
+ * we won't get any more characters.
+ */
+
+ while (1) {
+ int unthrottled;
+ tty_set_flow_change(tty, TTY_UNTHROTTLE_SAFE);
+ if (chars_in_buffer(tty) > TTY_THRESHOLD_UNTHROTTLE)
+ break;
+ unipi_tty_kick_worker(tty);
+ unthrottled = unipi_tty_unthrottle_safe(tty);
+ if (!unthrottled)
+ break;
+ }
+ __tty_set_flow_change(tty, 0);
+}
+
+/**
+ * reset_buffer_flags - reset buffer state
+ * @tty: terminal to reset
+ *
+ * Reset the read buffer counters and clear the flags.
+ * Called from unipi_tty_open() and unipi_tty_flush_buffer().
+ *
+ * Locking: caller holds exclusive termios_rwsem
+ * (or locking is not required)
+ */
+
+static void reset_buffer_flags(struct unipi_tty_data *ldata)
+{
+ ldata->read_head = ldata->read_tail = 0;
+ ldata->commit_head = 0;
+
+}
+
+static void unipi_tty_packet_mode_flush(struct tty_struct *tty)
+{
+ unsigned long flags;
+
+ if (tty->link->packet) {
+ spin_lock_irqsave(&tty->ctrl_lock, flags);
+ tty->ctrl_status |= TIOCPKT_FLUSHREAD;
+ spin_unlock_irqrestore(&tty->ctrl_lock, flags);
+ wake_up_interruptible(&tty->link->read_wait);
+ }
+}
+
+/**
+ * unipi_tty_flush_buffer - clean input queue
+ * @tty: terminal device
+ *
+ * Flush the input buffer. Called when the tty layer wants the
+ * buffer flushed (eg at hangup) or when the N_TTY line discipline
+ * internally has to clean the pending queue (for example some signals).
+ *
+ * Holds termios_rwsem to exclude producer/consumer while
+ * buffer indices are reset.
+ *
+ * Locking: ctrl_lock, exclusive termios_rwsem
+ */
+
+static void unipi_tty_flush_buffer(struct tty_struct *tty)
+{
+ unipi_tty_trace(KERN_INFO "UNIPI_LDISC: Flush start.");
+
+ down_write(&tty->termios_rwsem);
+ reset_buffer_flags(tty->disc_data);
+ unipi_tty_kick_worker(tty);
+
+ if (tty->link)
+ unipi_tty_packet_mode_flush(tty);
+ up_write(&tty->termios_rwsem);
+}
+
+
+
+static void __receive_buf(struct tty_struct *tty, const unsigned char *cp,
+ char *fp, int count)
+{
+ struct unipi_tty_data *ldata = tty->disc_data;
+ size_t n, head;
+
+ head = ldata->read_head & (N_TTY_BUF_SIZE - 1);
+ n = min_t(size_t, count, N_TTY_BUF_SIZE - head);
+ memcpy(read_buf_addr(ldata, head), cp, n);
+ ldata->read_head += n;
+ cp += n;
+ count -= n;
+
+ head = ldata->read_head & (N_TTY_BUF_SIZE - 1);
+ n = min_t(size_t, count, N_TTY_BUF_SIZE - head);
+ memcpy(read_buf_addr(ldata, head), cp, n);
+ ldata->read_head += n;
+
+ /* publish read_head to consumer */
+ smp_store_release(&ldata->commit_head, ldata->read_head);
+
+ if (read_cnt(ldata)) {
+ kill_fasync(&tty->fasync, SIGIO, POLL_IN);
+ wake_up_interruptible_poll(&tty->read_wait, POLLIN);
+ }
+}
+
+/**
+ * unipi_tty_receive_buf_common - process input
+ * @tty: device to receive input
+ * @cp: input chars
+ * @fp: flags for each char (if NULL, all chars are TTY_NORMAL)
+ * @count: number of input chars in @cp
+ *
+ * Called by the terminal driver when a block of characters has
+ * been received. This function must be called from soft contexts
+ * not from interrupt context. The driver is responsible for making
+ * calls one at a time and in order (or using flush_to_ldisc)
+ *
+ * Returns the # of input chars from @cp which were processed.
+ *
+ * In canonical mode, the maximum line length is 4096 chars (including
+ * the line termination char); lines longer than 4096 chars are
+ * truncated. After 4095 chars, input data is still processed but
+ * not stored. Overflow processing ensures the tty can always
+ * receive more input until at least one line can be read.
+ *
+ * In non-canonical mode, the read buffer will only accept 4095 chars;
+ * this provides the necessary space for a newline char if the input
+ * mode is switched to canonical.
+ *
+ * Note it is possible for the read buffer to _contain_ 4096 chars
+ * in non-canonical mode: the read buffer could already contain the
+ * maximum canon line of 4096 chars when the mode is switched to
+ * non-canonical.
+ *
+ * unipi_tty_receive_buf()/producer path:
+ * claims non-exclusive termios_rwsem
+ * publishes commit_head or canon_head
+ */
+static int
+unipi_tty_receive_buf_common(struct tty_struct *tty, const unsigned char *cp,
+ char *fp, int count, int flow)
+{
+ struct unipi_tty_data *ldata = tty->disc_data;
+ int room, n, rcvd = 0;
+
+ down_read(&tty->termios_rwsem);
+
+ while (1) {
+
+ size_t tail = smp_load_acquire(&ldata->read_tail);
+
+ room = N_TTY_BUF_SIZE - (ldata->read_head - tail);
+ room--;
+ if (room <= 0) {
+ room = 0;
+ ldata->no_room = flow;
+ }
+ n = min(count, room);
+ if (!n)
+ break;
+
+ __receive_buf(tty, cp, fp, n);
+
+ cp += n;
+ count -= n;
+ rcvd += n;
+ }
+
+ tty->receive_room = room;
+
+ /* Unthrottle if handling overflow on pty */
+ if (tty->driver->type == TTY_DRIVER_TYPE_PTY) {
+ } else
+ unipi_tty_check_throttle(tty);
+
+ up_read(&tty->termios_rwsem);
+
+ return rcvd;
+}
+
+static void unipi_tty_receive_buf(struct tty_struct *tty, const unsigned char *cp,
+ char *fp, int count)
+{
+ unipi_tty_trace(KERN_INFO "UNIPI_LDISC: Buf start.");
+ unipi_tty_receive_buf_common(tty, cp, fp, count, 0);
+}
+
+static int unipi_tty_receive_buf2(struct tty_struct *tty, const unsigned char *cp,
+ char *fp, int count)
+{
+ unipi_tty_trace(KERN_INFO "UNIPI_LDISC: Buf2 start.");
+ return unipi_tty_receive_buf_common(tty, cp, fp, count, 1);
+}
+
+/**
+ * unipi_tty_set_termios - termios data changed
+ * @tty: terminal
+ * @old: previous data
+ *
+ * Called by the tty layer when the user changes termios flags so
+ * that the line discipline can plan ahead. This function cannot sleep
+ * and is protected from re-entry by the tty layer. The user is
+ * guaranteed that this function will not be re-entered or in progress
+ * when the ldisc is closed.
+ *
+ * Locking: Caller holds tty->termios_rwsem
+ */
+
+static void unipi_tty_set_termios(struct tty_struct *tty, struct ktermios *old)
+{
+ struct unipi_tty_data *ldata = tty->disc_data;
+ int lx=0; int ix=0; int ox=0; int cx = 0;
+ if (old) {
+ lx = old->c_lflag;
+ ix = old->c_iflag;
+ ox = old->c_oflag;
+ cx = old->c_cflag;
+ }
+ unipi_tty_trace(KERN_INFO "UNIPI_LDISC: Termios new:0x%x %x %x %x old:0x%x %x %x %x", \
+ tty->termios.c_lflag, tty->termios.c_iflag, tty->termios.c_oflag, tty->termios.c_cflag,\
+ lx, ix, ox, cx);
+ if (!old || (old->c_lflag ^ tty->termios.c_lflag) & (ICANON | EXTPROC)) {
+ ldata->commit_head = ldata->read_head;
+ }
+
+ /*
+ * Fix tty hang when I_IXON(tty) is cleared, but the tty
+ * been stopped by STOP_CHAR(tty) before it.
+ */
+ if (!I_IXON(tty) && old && (old->c_iflag & IXON) && !tty->flow_stopped) {
+ start_tty(tty);
+ }
+
+ /* The termios change make the tty ready for I/O */
+ wake_up_interruptible(&tty->write_wait);
+ wake_up_interruptible(&tty->read_wait);
+}
+
+/**
+ * unipi_tty_close - close the ldisc for this tty
+ * @tty: device
+ *
+ * Called from the terminal layer when this line discipline is
+ * being shut down, either because of a close or becsuse of a
+ * discipline change. The function will not be called while other
+ * ldisc methods are in progress.
+ */
+
+static void unipi_tty_close(struct tty_struct *tty)
+{
+ struct unipi_tty_data *ldata = tty->disc_data;
+
+ if (tty->link)
+ unipi_tty_packet_mode_flush(tty);
+
+ vfree(ldata);
+ tty->disc_data = NULL;
+ unipi_tty_trace(KERN_INFO "UNIPI_LDISC: Close OK.");
+}
+
+/**
+ * unipi_tty_open - open an ldisc
+ * @tty: terminal to open
+ *
+ * Called when this line discipline is being attached to the
+ * terminal device. Can sleep. Called serialized so that no
+ * other events will occur in parallel. No further open will occur
+ * until a close.
+ */
+
+static int unipi_tty_open(struct tty_struct *tty)
+{
+ struct unipi_tty_data *ldata;
+
+ /* Currently a malloc failure here can panic */
+ ldata = vmalloc(sizeof(*ldata));
+ if (!ldata)
+ goto err;
+
+ mutex_init(&ldata->atomic_read_lock);
+ mutex_init(&ldata->output_lock);
+
+ tty->disc_data = ldata;
+ reset_buffer_flags(tty->disc_data);
+ ldata->no_room = 0;
+ tty->closing = 0;
+ /* indicate buffer work may resume */
+ clear_bit(TTY_LDISC_HALTED, &tty->flags);
+ unipi_tty_set_termios(tty, NULL);
+ tty_unthrottle(tty);
+
+ unipi_tty_trace(KERN_INFO "UNIPI_LDISC: Open OK.");
+
+ return 0;
+err:
+ return -ENOMEM;
+}
+
+static inline int input_available_p(struct tty_struct *tty, int poll)
+{
+ struct unipi_tty_data *ldata = tty->disc_data;
+ int amt = poll && !TIME_CHAR(tty) && MIN_CHAR(tty) ? MIN_CHAR(tty) : 1;
+
+ return ldata->commit_head - ldata->read_tail >= amt;
+}
+
+/**
+ * copy_from_read_buf - copy read data directly
+ * @tty: terminal device
+ * @b: user data
+ * @nr: size of data
+ *
+ * Helper function to speed up unipi_tty_read. It is only called when
+ * ICANON is off; it copies characters straight from the tty queue to
+ * user space directly. It can be profitably called twice; once to
+ * drain the space from the tail pointer to the (physical) end of the
+ * buffer, and once to drain the space from the (physical) beginning of
+ * the buffer to head pointer.
+ *
+ * Called under the ldata->atomic_read_lock sem
+ *
+ * unipi_tty_read()/consumer path:
+ * caller holds non-exclusive termios_rwsem
+ * read_tail published
+ */
+
+static int copy_from_read_buf(struct tty_struct *tty,
+ unsigned char __user **b,
+ size_t *nr)
+
+{
+ struct unipi_tty_data *ldata = tty->disc_data;
+ int retval;
+ size_t n;
+ size_t head = smp_load_acquire(&ldata->commit_head);
+ size_t tail = ldata->read_tail & (N_TTY_BUF_SIZE - 1);
+
+ retval = 0;
+ n = min(head - ldata->read_tail, N_TTY_BUF_SIZE - tail);
+ n = min(*nr, n);
+ if (n) {
+ const unsigned char *from = read_buf_addr(ldata, tail);
+ retval = copy_to_user(*b, from, n);
+ n -= retval;
+ //tty_audit_add_data(tty, from, n);
+ smp_store_release(&ldata->read_tail, ldata->read_tail + n);
+ *b += n;
+ *nr -= n;
+ }
+ return retval;
+}
+
+
+
+/**
+ * unipi_tty_read - read function for tty
+ * @tty: tty device
+ * @file: file object
+ * @buf: userspace buffer pointer
+ * @nr: size of I/O
+ *
+ * Perform reads for the line discipline. We are guaranteed that the
+ * line discipline will not be closed under us but we may get multiple
+ * parallel readers and must handle this ourselves. We may also get
+ * a hangup. Always called in user context, may sleep.
+ *
+ * This code must be sure never to sleep through a hangup.
+ *
+ * unipi_tty_read()/consumer path:
+ * claims non-exclusive termios_rwsem
+ * publishes read_tail
+ */
+
+static ssize_t unipi_tty_read(struct tty_struct *tty, struct file *file,
+ unsigned char __user *buf, size_t nr)
+{
+ struct unipi_tty_data *ldata = tty->disc_data;
+ struct tty_port *port = tty->port;
+ unsigned char __user *b = buf;
+ DEFINE_WAIT_FUNC(wait, woken_wake_function);
+ int minimum, time;
+ ssize_t retval = 0;
+ long timeout;
+ int packet;
+ size_t tail;
+
+ /*
+ * Internal serialization of reads.
+ */
+ unipi_tty_trace(KERN_INFO "UNIPI_LDISC: Read start.");
+ if (file->f_flags & O_NONBLOCK) {
+ if (!mutex_trylock(&ldata->atomic_read_lock))
+ return -EAGAIN;
+ } else {
+ if (mutex_lock_interruptible(&ldata->atomic_read_lock))
+ return -ERESTARTSYS;
+ }
+
+ down_read(&tty->termios_rwsem);
+
+ minimum = time = 0;
+ timeout = MAX_SCHEDULE_TIMEOUT;
+
+ minimum = MIN_CHAR(tty);
+ if (minimum) {
+ time = (HZ / 10) * TIME_CHAR(tty);
+ } else {
+ timeout = (HZ / 10) * TIME_CHAR(tty);
+ minimum = 1;
+ }
+
+ packet = tty->packet;
+ tail = ldata->read_tail;
+
+ add_wait_queue(&tty->read_wait, &wait);
+ while (nr) {
+ /* First test for status change. */
+ if (packet && tty->link->ctrl_status) {
+ unsigned char cs;
+ if (b != buf)
+ break;
+ spin_lock_irq(&tty->link->ctrl_lock);
+ cs = tty->link->ctrl_status;
+ tty->link->ctrl_status = 0;
+ spin_unlock_irq(&tty->link->ctrl_lock);
+ if (put_user(cs, b)) {
+ retval = -EFAULT;
+ break;
+ }
+ b++;
+ nr--;
+ break;
+ }
+
+ if (!input_available_p(tty, 0)) {
+ up_read(&tty->termios_rwsem);
+ //tty_buffer_flush_work(tty->port);
+ flush_work(&port->buf.work);
+ down_read(&tty->termios_rwsem);
+ if (!input_available_p(tty, 0)) {
+ if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) {
+ retval = -EIO;
+ break;
+ }
+ if (tty_hung_up_p(file))
+ break;
+ /*
+ * Abort readers for ttys which never actually
+ * get hung up. See __tty_hangup().
+ */
+#ifdef TTY_HUPPING
+ if (test_bit(TTY_HUPPING, &tty->flags))
+ break;
#endif
- memset(&neuronspi_tty_ldisc, 0, sizeof(neuronspi_tty_ldisc));
- n_tty_inherit_ops(&neuronspi_tty_ldisc);
- neuronspi_tty_ldisc.magic = TTY_LDISC_MAGIC;
- neuronspi_tty_ldisc.name = "unipi_tty";
- neuronspi_tty_ldisc.owner = THIS_MODULE;
- err = tty_register_ldisc(N_PROFIBUS_FDL, &neuronspi_tty_ldisc);
+ if (!timeout)
+ break;
+ if (file->f_flags & O_NONBLOCK) {
+ retval = -EAGAIN;
+ break;
+ }
+ if (signal_pending(current)) {
+ retval = -ERESTARTSYS;
+ break;
+ }
+ up_read(&tty->termios_rwsem);
+
+ timeout = wait_woken(&wait, TASK_INTERRUPTIBLE,
+ timeout);
+
+ down_read(&tty->termios_rwsem);
+ continue;
+ }
+ }
+
+ {
+ int uncopied;
+
+ /* Deal with packet mode. */
+ if (packet && b == buf) {
+ if (put_user(TIOCPKT_DATA, b)) {
+ retval = -EFAULT;
+ break;
+ }
+ b++;
+ nr--;
+ }
+
+ uncopied = copy_from_read_buf(tty, &b, &nr);
+ uncopied += copy_from_read_buf(tty, &b, &nr);
+ if (uncopied) {
+ retval = -EFAULT;
+ break;
+ }
+ }
+
+ unipi_tty_check_unthrottle(tty);
+
+ if (b - buf >= minimum)
+ break;
+ if (time)
+ timeout = time;
+ }
+ if (tail != ldata->read_tail)
+ unipi_tty_kick_worker(tty);
+ up_read(&tty->termios_rwsem);
+
+ remove_wait_queue(&tty->read_wait, &wait);
+ mutex_unlock(&ldata->atomic_read_lock);
+
+ if (b - buf)
+ retval = b - buf;
+
+ return retval;
+}
+
+/**
+ * unipi_tty_write - write function for tty
+ * @tty: tty device
+ * @file: file object
+ * @buf: userspace buffer pointer
+ * @nr: size of I/O
+ *
+ * Write function of the terminal device. This is serialized with
+ * respect to other write callers but not to termios changes, reads
+ * and other such events. Since the receive code will echo characters,
+ * thus calling driver write methods, the output_lock is used in
+ * the output processing functions called here as well as in the
+ * echo processing function to protect the column state and space
+ * left in the buffer.
+ *
+ * This code must be sure never to sleep through a hangup.
+ *
+ * Locking: output_lock to protect column state and space left
+ * (note that the process_output*() functions take this
+ * lock themselves)
+ */
+
+static ssize_t unipi_tty_write(struct tty_struct *tty, struct file *file,
+ const unsigned char *buf, size_t nr)
+{
+ const unsigned char *b = buf;
+ DEFINE_WAIT_FUNC(wait, woken_wake_function);
+ struct unipi_tty_data *ldata;
+ int c;
+ ssize_t retval = 0;
+
+ unipi_tty_trace(KERN_INFO "UNIPI_LDISC: Write start.");
+ down_read(&tty->termios_rwsem);
+
+ add_wait_queue(&tty->write_wait, &wait);
+ while (1) {
+ if (signal_pending(current)) {
+ retval = -ERESTARTSYS;
+ break;
+ }
+ if (tty_hung_up_p(file) || (tty->link && !tty->link->count)) {
+ retval = -EIO;
+ break;
+ }
+
+ ldata = tty->disc_data;
+
+ while (nr > 0) {
+ mutex_lock(&ldata->output_lock);
+ c = tty->ops->write(tty, b, nr);
+ mutex_unlock(&ldata->output_lock);
+ if (c < 0) {
+ retval = c;
+ goto break_out;
+ }
+ if (!c)
+ break;
+ b += c;
+ nr -= c;
+ }
+
+ if (!nr)
+ break;
+ if (file->f_flags & O_NONBLOCK) {
+ retval = -EAGAIN;
+ break;
+ }
+ up_read(&tty->termios_rwsem);
+
+ wait_woken(&wait, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);
+
+ down_read(&tty->termios_rwsem);
+ }
+break_out:
+ remove_wait_queue(&tty->write_wait, &wait);
+ if (nr && tty->fasync)
+ set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
+ up_read(&tty->termios_rwsem);
+ return (b - buf) ? b - buf : retval;
+}
+
+/**
+ * unipi_tty_poll - poll method for N_TTY
+ * @tty: terminal device
+ * @file: file accessing it
+ * @wait: poll table
+ *
+ * Called when the line discipline is asked to poll() for data or
+ * for special events. This code is not serialized with respect to
+ * other events save open/close.
+ *
+ * This code must be sure never to sleep through a hangup.
+ * Called without the kernel lock held - fine
+ */
+
+static unsigned int unipi_tty_poll(struct tty_struct *tty, struct file *file,
+ poll_table *wait)
+{
+ unsigned int mask = 0;
+ struct tty_port *port = tty->port;
+
+ //unipi_tty_trace(KERN_INFO "UNIPI_LDISC: Poll start.");
+ poll_wait(file, &tty->read_wait, wait);
+ poll_wait(file, &tty->write_wait, wait);
+ if (input_available_p(tty, 1))
+ mask |= POLLIN | POLLRDNORM;
+ else {
+ //tty_buffer_flush_work(tty->port);
+ flush_work(&port->buf.work);
+ if (input_available_p(tty, 1))
+ mask |= POLLIN | POLLRDNORM;
+ }
+ if (tty->packet && tty->link->ctrl_status)
+ mask |= POLLPRI | POLLIN | POLLRDNORM;
+ if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
+ mask |= POLLHUP;
+ if (tty_hung_up_p(file))
+ mask |= POLLHUP;
+ if (tty->ops->write && !tty_is_writelocked(tty) &&
+ tty_chars_in_buffer(tty) < WAKEUP_CHARS &&
+ tty_write_room(tty) > 0)
+ mask |= POLLOUT | POLLWRNORM;
+ return mask;
+}
+
+
+static int unipi_tty_ioctl(struct tty_struct *tty, struct file *file,
+ unsigned int cmd, unsigned long arg)
+{
+ struct unipi_tty_data *ldata = tty->disc_data;
+ int retval;
+
+ unipi_tty_trace(KERN_INFO "UNIPI_LDISC: Ioctl start. cmd=%x", cmd);
+ switch (cmd) {
+ case TIOCOUTQ:
+ return put_user(tty_chars_in_buffer(tty), (int __user *) arg);
+ case TIOCINQ:
+ down_write(&tty->termios_rwsem);
+ retval = read_cnt(ldata);
+ up_write(&tty->termios_rwsem);
+ return put_user(retval, (unsigned int __user *) arg);
+ default:
+ return n_tty_ioctl_helper(tty, file, cmd, arg);
+ }
+}
+
+static long unipi_tty_compat_ioctl(struct tty_struct *tty, struct file *file,
+ unsigned int cmd, unsigned long arg)
+{
+ int retval;
+
+ unipi_tty_trace(KERN_INFO "UNIPI_LDISC: Compat_ioctl start. cmd=%x", cmd);
+ switch (cmd) {
+ case 0x5481:
+ case 0x5480:
+ if (tty->ops->ioctl) {
+ retval = tty->ops->ioctl(tty, cmd, (unsigned long) compat_ptr(arg));
+ if (retval != -ENOIOCTLCMD)
+ return retval;
+ }
+ //return tty_mode_ioctl(tty, file, cmd, (unsigned long) compat_ptr(arg));
+ default:
+ return n_tty_compat_ioctl_helper(tty, file, cmd, arg);
+ }
+}
+
+
+static struct tty_ldisc_ops unipi_tty_ops = {
+ .magic = TTY_LDISC_MAGIC,
+ .owner = THIS_MODULE,
+ .name = "unipi_tty",
+ .open = unipi_tty_open,
+ .close = unipi_tty_close,
+ .flush_buffer = unipi_tty_flush_buffer,
+ .read = unipi_tty_read,
+ .write = unipi_tty_write,
+ .ioctl = unipi_tty_ioctl,
+ .compat_ioctl = unipi_tty_compat_ioctl,
+ .set_termios = unipi_tty_set_termios,
+ .poll = unipi_tty_poll,
+ .receive_buf = unipi_tty_receive_buf,
+ .write_wakeup = unipi_tty_write_wakeup,
+ .receive_buf2 = unipi_tty_receive_buf2,
+};
+
+
+
+int __init unipi_tty_init(void)
+{
+ int err;
+ unipi_tty_trace(KERN_INFO "UNIPISPI: TTY Init\n");
+ err = tty_register_ldisc(N_PROFIBUS_FDL, &unipi_tty_ops);
if (err) {
printk(KERN_INFO "UNIPISPI: UniPi line discipline registration failed. (%d)", err);
return err;
git.graph-it.com / graphit / unipi-kernel.git / commitdiff