syscons: provide a first iteration of cngrab/cnungrab implementation

- put underlying keyboard(s) into the polling mode for the whole
  duration of the grab, instead of the previous behavior of going into
  and out of the polling mode around each polling attempt
- ditto for setting K_XLATE mode and enabling a disabled keyboard

Inspired by:	bde
MFC after:	2 months

2 files changed, 37 insertions, 19 deletions

diff --git a/sys/dev/syscons/syscons.c b/sys/dev/syscons/syscons.c
index f25026e855fd..cc54de139fbd 100644
--- a/sys/dev/syscons/syscons.c
+++ b/sys/dev/syscons/syscons.c
@@ -1613,11 +1613,46 @@ sc_cnterm(struct consdev *cp)
 static void
 sc_cngrab(struct consdev *cp)
 {
+    scr_stat *scp;
+
+    scp = sc_console->sc->cur_scp;
+    if (scp->sc->kbd == NULL)
+	return;
+
+    if (scp->grabbed++ > 0)
+	return;
+
+    /*
+     * Make sure the keyboard is accessible even when the kbd device
+     * driver is disabled.
+     */
+    kbdd_enable(scp->sc->kbd);
+
+    /* we shall always use the keyboard in the XLATE mode here */
+    scp->kbd_prev_mode = scp->kbd_mode;
+    scp->kbd_mode = K_XLATE;
+    (void)kbdd_ioctl(scp->sc->kbd, KDSKBMODE, (caddr_t)&scp->kbd_mode);
+
+    kbdd_poll(scp->sc->kbd, TRUE);
 }
 
 static void
 sc_cnungrab(struct consdev *cp)
 {
+    scr_stat *scp;
+
+    scp = sc_console->sc->cur_scp;	/* XXX */
+    if (scp->sc->kbd == NULL)
+	return;
+
+    if (--scp->grabbed > 0)
+	return;
+
+    kbdd_poll(scp->sc->kbd, FALSE);
+
+    scp->kbd_mode = scp->kbd_prev_mode;
+    (void)kbdd_ioctl(scp->sc->kbd, KDSKBMODE, (caddr_t)&scp->kbd_mode);
+    kbdd_disable(scp->sc->kbd);
 }
 
 static void
@@ -1675,7 +1710,6 @@ sc_cngetc(struct consdev *cd)
     static int fkeycp;
     scr_stat *scp;
     const u_char *p;
-    int cur_mode;
     int s = spltty();	/* block sckbdevent and scrn_timer while we poll */
     int c;
 
@@ -1699,25 +1733,7 @@ sc_cngetc(struct consdev *cd)
 	return -1;
     }
 
-    /* 
-     * Make sure the keyboard is accessible even when the kbd device
-     * driver is disabled.
-     */
-    kbdd_enable(scp->sc->kbd);
-
-    /* we shall always use the keyboard in the XLATE mode here */
-    cur_mode = scp->kbd_mode;
-    scp->kbd_mode = K_XLATE;
-    (void)kbdd_ioctl(scp->sc->kbd, KDSKBMODE, (caddr_t)&scp->kbd_mode);
-
-    kbdd_poll(scp->sc->kbd, TRUE);
     c = scgetc(scp->sc, SCGETC_CN | SCGETC_NONBLOCK);
-    kbdd_poll(scp->sc->kbd, FALSE);
-
-    scp->kbd_mode = cur_mode;
-    (void)kbdd_ioctl(scp->sc->kbd, KDSKBMODE, (caddr_t)&scp->kbd_mode);
-    kbdd_disable(scp->sc->kbd);
-    splx(s);
 
     switch (KEYFLAGS(c)) {
     case 0:	/* normal char */
diff --git a/sys/dev/syscons/syscons.h b/sys/dev/syscons/syscons.h
index 7280d8931c50..e88ac431d284 100644
--- a/sys/dev/syscons/syscons.h
+++ b/sys/dev/syscons/syscons.h
@@ -301,7 +301,9 @@ typedef struct scr_stat {
 	void		*ts;
 
 	int	 	status;			/* status (bitfield) */
+	int		grabbed;
 	int		kbd_mode;		/* keyboard I/O mode */
+	int		kbd_prev_mode;		/* keyboard I/O mode */
 
 	int		cursor_pos;		/* cursor buffer position */
 	int		cursor_oldpos;		/* cursor old buffer position */