pcmcia: avoid late calls to pccard_validate_cis

pccard_validate_cis() nowadays destroys the CIS cache. Therefore,
calling it after card setup should be avoided. We can't control
the deprecated PCMCIA ioctl (which is only used on ARM nowadays),
but we can avoid -- and report -- any other calls.
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>

drivers/pcmcia/cistpl.c

@@ -1484,6 +1484,11 @@ int pccard_validate_cis(struct pcmcia_socket *s, unsigned int *info)
 	if (!s)
 		return -EINVAL;
 
+	if (s->functions) {
+		WARN_ON(1);
+		return -EINVAL;
+	}
+
 	/* We do not want to validate the CIS cache... */
 	mutex_lock(&s->ops_mutex);
 	destroy_cis_cache(s);
@@ -1639,7 +1644,7 @@ static ssize_t pccard_show_cis(struct kobject *kobj,
 		count = 0;
 	else {
 		struct pcmcia_socket *s;
-		unsigned int chains;
+		unsigned int chains = 1;
 
 		if (off + count > size)
 			count = size - off;
@@ -1648,7 +1653,7 @@ static ssize_t pccard_show_cis(struct kobject *kobj,
 
 		if (!(s->state & SOCKET_PRESENT))
 			return -ENODEV;
-		if (pccard_validate_cis(s, &chains))
+		if (!s->functions && pccard_validate_cis(s, &chains))
 			return -EIO;
 		if (!chains)
 			return -ENODATA;