Changeset 540 for trunk/kernel/devices/dev_txt.c

Timestamp:

Sep 21, 2018, 10:22:02 PM (6 years ago)

Author:

nicolas.van.phan@…

Message:

TTY MUX 5/5 : Multiplex TTY character receiving

The multiplexing for receving chars is done by redirecting
the IRQs (when a char is received) to the right chdev (so the right
server DEV thread). When the user types an uppercase letter,
it is treated as a special char used to change the active tty
by redirecting the IRQs to the chdev corresponding to the appropriate
channel.

Add some documentation and example in the code.

Add mfences calls in spinlock_unlock_busy fix a bug on letty physical
hardware.

File:

• trunk/kernel/devices/dev_txt.c (modified) (3 diffs)

trunk/kernel/devices/dev_txt.c

@@ -87 +87 @@
 
     // no server thread and no IRQ routing for TXT0 
+    // except for LETI where there MUST be IRQ routing
     // no server thread for IMPL_TXT_RS2 (multiplexed in software, not hardware)
     if( channel != 0 && impl != IMPL_TXT_RS2 )
@@ -93 +94 @@
         lid_t lid = cluster_select_local_core();
 
+        // The unique IRQ from cluster 00's MTTY must be bound to a RX chdev
+        // so that all IRQs are considered as RX IRQs and treated as such
+        // Indeed, IRQs are raised by the MTTY only on user keystroke, so IRQs must
+        // always be considered as RX IRQs.
+        if ( ( impl != IMPL_TXT_MTY ) || ( channel == 1 && is_rx == 1 ) ) 
+        {
         // bind IRQ to the selected core
         dev_pic_bind_irq( lid , txt );
@@ -98 +105 @@
         // enable IRQ
         dev_pic_enable_irq( lid , XPTR( local_cxy , txt ) );
+        }
 
         // create server thread