boot/console: handle consoles that fail to probe

- clarify meaning of console flags
- perform i/o via a console only if both of the following conditions are met:
   o console is active (selected by user or config)
   o console flags that it can perform the operation
- warn if a chosen console can not work (the warning may go nowhere without
  working and active console, though)

Reviewed by:	jhb
Tested by:	Uffe Jakobsen <uffe@uffe.org>,
		Olivier Cochard-Labbe' <olivier@cochard.me>
MFC after:	26 days

2 files changed, 17 insertions, 10 deletions

diff --git a/sys/boot/common/bootstrap.h b/sys/boot/common/bootstrap.h
index f6eab3d..516b8a5 100644
--- a/sys/boot/common/bootstrap.h
+++ b/sys/boot/common/bootstrap.h
@@ -109,10 +109,10 @@ struct console
     const char	*c_name;
     const char	*c_desc;
     int		c_flags;
-#define C_PRESENTIN	(1<<0)
-#define C_PRESENTOUT	(1<<1)
-#define C_ACTIVEIN	(1<<2)
-#define C_ACTIVEOUT	(1<<3)
+#define C_PRESENTIN	(1<<0)	    /* console can provide input */
+#define C_PRESENTOUT	(1<<1)	    /* console can provide output */
+#define C_ACTIVEIN	(1<<2)	    /* user wants input from console */
+#define C_ACTIVEOUT	(1<<3)	    /* user wants output to console */
     void	(* c_probe)(struct console *cp);	/* set c_flags to match hardware */
     int		(* c_init)(int arg);			/* reinit XXX may need more args */
     void	(* c_out)(int c);			/* emit c */
diff --git a/sys/boot/common/console.c b/sys/boot/common/console.c
index d140a96..6c1fdab 100644
--- a/sys/boot/common/console.c
+++ b/sys/boot/common/console.c
@@ -100,11 +100,12 @@ getchar(void)
 {
     int		cons;
     int		rv;
-    
+
     /* Loop forever polling all active consoles */
     for(;;)
 	for (cons = 0; consoles[cons] != NULL; cons++)
-	    if ((consoles[cons]->c_flags & C_ACTIVEIN) && 
+	    if ((consoles[cons]->c_flags & (C_PRESENTIN | C_ACTIVEIN)) ==
+		(C_PRESENTIN | C_ACTIVEIN) &&
 		((rv = consoles[cons]->c_in()) != -1))
 		return(rv);
 }
@@ -115,7 +116,8 @@ ischar(void)
     int		cons;
 
     for (cons = 0; consoles[cons] != NULL; cons++)
-	if ((consoles[cons]->c_flags & C_ACTIVEIN) && 
+	if ((consoles[cons]->c_flags & (C_PRESENTIN | C_ACTIVEIN)) ==
+	    (C_PRESENTIN | C_ACTIVEIN) &&
 	    (consoles[cons]->c_ready() != 0))
 		return(1);
     return(0);
@@ -125,13 +127,14 @@ void
 putchar(int c)
 {
     int		cons;
-    
+
     /* Expand newlines */
     if (c == '\n')
 	putchar('\r');
-    
+
     for (cons = 0; consoles[cons] != NULL; cons++)
-	if (consoles[cons]->c_flags & C_ACTIVEOUT)
+	if ((consoles[cons]->c_flags & (C_PRESENTOUT | C_ACTIVEOUT)) ==
+	    (C_PRESENTOUT | C_ACTIVEOUT))
 	    consoles[cons]->c_out(c);
 }
 
@@ -220,6 +223,10 @@ cons_change(const char *string)
 	if (cons >= 0) {
 	    consoles[cons]->c_flags |= C_ACTIVEIN | C_ACTIVEOUT;
 	    consoles[cons]->c_init(0);
+	    if ((consoles[cons]->c_flags & (C_PRESENTIN | C_PRESENTOUT)) !=
+		(C_PRESENTIN | C_PRESENTOUT))
+		printf("console %s failed to initialize\n",
+		    consoles[cons]->c_name);
 	}
     }