[rtems commit] termios: Pass number of sent chars to l_start

[Christian Mauderer]

Module:    rtems
Branch:    5
Commit:    9942ff80c46d5658f22dc5ac9fae4dcaba4f9966
Changeset: http://git.rtems.org/rtems/commit/?id=9942ff80c46d5658f22dc5ac9fae4dcaba4f9966

Author:    Christian Mauderer <christian.mauderer at embedded-brains.de>
Date:      Thu Aug 12 09:51:55 2021 +0200

termios: Pass number of sent chars to l_start

At the moment the line discipline start function (l_start) has no
possibility to get feedback about the number of characters that have
been sent. This patch passes that information via an additional
parameter.

The change might trigger a warning on existing code because of a pointer
mismatch but it shouldn't break it. An existing function with the old
API will just ignore the additional parameter.

Update #4494

---

 cpukit/include/rtems/termiostypes.h | 6 +++++-
 cpukit/libcsupport/src/termios.c    | 5 +++--
 2 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/cpukit/include/rtems/termiostypes.h b/cpukit/include/rtems/termiostypes.h
index 6930e59..59b1b3d 100644
--- a/cpukit/include/rtems/termiostypes.h
+++ b/cpukit/include/rtems/termiostypes.h
@@ -367,6 +367,10 @@ typedef struct rtems_termios_tty {
    */
   rtems_id                rxTaskId;
   rtems_id                txTaskId;
+  /*
+   * Information for the tx task how many characters have been dequeued.
+   */
+  int                     txTaskCharsDequeued;
 
   /*
    * line discipline related stuff
@@ -482,7 +486,7 @@ struct rtems_termios_linesw {
   int (*l_read )(struct rtems_termios_tty *tp,rtems_libio_rw_args_t *args);
   int (*l_write)(struct rtems_termios_tty *tp,rtems_libio_rw_args_t *args);
   int (*l_rint )(int c,struct rtems_termios_tty *tp);
-  int (*l_start)(struct rtems_termios_tty *tp);
+  int (*l_start)(struct rtems_termios_tty *tp,int len);
   int (*l_ioctl)(struct rtems_termios_tty *tp,rtems_libio_ioctl_args_t *args);
   int (*l_modem)(struct rtems_termios_tty *tp,int flags);
 };
diff --git a/cpukit/libcsupport/src/termios.c b/cpukit/libcsupport/src/termios.c
index 75925cf..2b35420 100644
--- a/cpukit/libcsupport/src/termios.c
+++ b/cpukit/libcsupport/src/termios.c
@@ -1966,6 +1966,7 @@ rtems_termios_dequeue_characters (void *ttyp, int len)
     /*
      * send wake up to transmitter task
      */
+    tty->txTaskCharsDequeued = len;
     sc = rtems_event_send(tty->txTaskId, TERMIOS_TX_START_EVENT);
     if (sc != RTEMS_SUCCESSFUL)
       rtems_fatal_error_occurred (sc);
@@ -1977,7 +1978,7 @@ rtems_termios_dequeue_characters (void *ttyp, int len)
      * call PPP line discipline start function
      */
     if (rtems_termios_linesw[tty->t_line].l_start != NULL) {
-      rtems_termios_linesw[tty->t_line].l_start(tty);
+      rtems_termios_linesw[tty->t_line].l_start(tty, len);
     }
     return 0; /* nothing to output in IRQ... */
   }
@@ -2012,7 +2013,7 @@ static rtems_task rtems_termios_txdaemon(rtems_task_argument argument)
      * call any line discipline start function
      */
     if (rtems_termios_linesw[tty->t_line].l_start != NULL) {
-      rtems_termios_linesw[tty->t_line].l_start(tty);
+      rtems_termios_linesw[tty->t_line].l_start(tty, tty->txTaskCharsDequeued);
 
       if (tty->t_line == PPPDISC) {
         /*