2003-02-28 Roland McGrath <roland@frob.com>

* oskit/osenv_irq.c (console_irq, console_irq_handler): New variables.
	(irq_alloc, irq_free): Implement special kludge with console_irq.
	* oskit/ds_osenv.c (ds_osenv_init): Set console_irq before
	initializing the minimal interrupt-driven console.

2 files changed, 58 insertions, 5 deletions

diff --git a/oskit/ds_osenv.c b/oskit/ds_osenv.c
index 407556bb..13591161 100644
--- a/oskit/ds_osenv.c
+++ b/oskit/ds_osenv.c
@@ -16,6 +16,8 @@ extern int serial_console;	/* base_console_init.c */
 
 oskit_stream_t *ds_console_stream;
 
+extern int console_irq;		/* kludge in osenv_irq.c */
+
 
 void
 ds_osenv_init (void)
@@ -44,6 +46,7 @@ ds_osenv_init (void)
       param.c_lflag &= ~ECHO;
       param.c_iflag &= ~ICRNL;
       param.c_oflag &= ~OPOST;
+      console_irq = -1;
       rc = cq_com_console_init (port, &param,
 				oskit_create_osenv_irq (),
 				intr,
@@ -53,6 +56,7 @@ ds_osenv_init (void)
   else
     {
       oskit_osenv_intr_t *intr = oskit_create_osenv_intr ();
+      console_irq = -1;
       rc = cq_direct_console_init (oskit_create_osenv_irq (),
 				   intr,
 				   oskit_create_osenv_sleep (intr),
diff --git a/oskit/osenv_irq.c b/oskit/osenv_irq.c
index 8ebb92e5..0d7c1a7f 100644
--- a/oskit/osenv_irq.c
+++ b/oskit/osenv_irq.c
@@ -118,6 +118,16 @@ irq_release(oskit_osenv_irq_t *s)
 	return 1;
 }
 
+
+/* This is a special kludge for the minimal console.  If console_irq is -1
+   during the first irq_alloc, we set it to the irq being allocated.
+   Thereafter, allocating that irq will silently succeed and override
+   the handler installed for the minimal console, which we save in
+   console_irq_handler; freeing that irq will restore the console handler.  */
+
+int console_irq;
+static struct int_handler *console_irq_handler;
+
 static OSKIT_COMDECL_U
 irq_alloc(oskit_osenv_irq_t *o, int irq,
 	  void (*handler)(void *), void *data, int flags)
@@ -153,6 +163,29 @@ irq_alloc(oskit_osenv_irq_t *o, int irq,
 	temp->data = data;
 	temp->next = NULL;
 
+	/* Special hack for the minimal com and direct console devices.  */
+	if (console_irq == -1) {
+		/* ds_osenv_init sets console_irq to -1 while initializing the
+		   console, so we know this is the irq being allocated for it.
+		   XXX we assume there is only one!
+		*/
+		assert (first_time);
+		console_irq = irq;
+	}
+	else if (irq == console_irq && console_irq_handler == NULL) {
+		/* Attempting to re-allocate the console's irq.
+		   This must be a real device driver taking over
+		   from the minimal console.  Let it.  */
+		assert (! first_time);
+		assert (handlers[irq] != NULL);
+		console_irq_handler = handlers[irq];
+		osenv_log(OSENV_LOG_DEBUG,
+			  "irq %d stolen from console\n", irq);
+		handlers[irq] = temp;
+		shareable[irq] = (flags & OSENV_IRQ_SHAREABLE) != 0;
+		return 0;
+	}
+
 	/*
 	 * Fail if the irq is already in use
 	 * and either the new handler or the existing handler
@@ -208,11 +241,27 @@ irq_free(oskit_osenv_irq_t *o, int irq,
 	if (temp != NULL &&
 	    temp->func == handler && temp->data == data &&
 	    temp->next == NULL) {
-		osenv_irq_disable(irq);
-		handlers[irq] = NULL;
-		intpri[irq] = SPL0;
-		ivect[irq] = intnull;
-		iunit[irq] = irq;
+		if (irq == console_irq) {
+			/* Special hack for the minimal console's irq.
+			   Restore the console's handler now that no real
+			   driver is using it.
+			   XXX this is probably not actually useful since
+			   the driver won't have left the device in the same
+			   state the minimal console driver expects.
+			*/
+			handlers[irq] = console_irq_handler;
+			shareable[irq] = 0;
+			console_irq_handler = NULL;
+			osenv_log(OSENV_LOG_DEBUG,
+				  "irq %d returned to console\n", irq);
+		}
+		else {
+			osenv_irq_disable(irq);
+			handlers[irq] = NULL;
+			intpri[irq] = SPL0;
+			ivect[irq] = intnull;
+			iunit[irq] = irq;
+		}
 		kfree(temp, sizeof(struct int_handler));
 		return;
 	}