mac80211: better rate control algorithm selection

This patch changes mac80211's Kconfig/Makefile to:
 * select between the PID and the SIMPLE rate control
   algorithm as default
 * always allow tri-state for the rate control algorithms,
   building those that are selected 'y' into the mac80211
   module (if that is a module, otherwise all into the kernel)
 * force the default rate control algorithm to be built into
   mac80211

It also makes both rate control algorithms proper modules again
with MODULE_LICENSE etc.

Only if EMBEDDED is the user allowed to select "NONE" as default
which will cause no algorithm to be selected, this will work
only when the driver brings one itself (e.g. iwlwifi drivers).

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/mac80211/rc80211_pid_algo.c b/net/mac80211/rc80211_pid_algo.c
index da35290..0995bb9 100644
--- a/net/mac80211/rc80211_pid_algo.c
+++ b/net/mac80211/rc80211_pid_algo.c
@@ -12,7 +12,7 @@
 #include <linux/netdevice.h>
 #include <linux/types.h>
 #include <linux/skbuff.h>
-
+#include <linux/debugfs.h>
 #include <net/mac80211.h>
 #include "ieee80211_rate.h"
 
@@ -492,7 +492,7 @@
 	kfree(spinfo);
 }
 
-struct rate_control_ops mac80211_rcpid = {
+static struct rate_control_ops mac80211_rcpid = {
 	.name = "pid",
 	.tx_status = rate_control_pid_tx_status,
 	.get_rate = rate_control_pid_get_rate,
@@ -507,3 +507,23 @@
 	.remove_sta_debugfs = rate_control_pid_remove_sta_debugfs,
 #endif
 };
+
+MODULE_DESCRIPTION("PID controller based rate control algorithm");
+MODULE_AUTHOR("Stefano Brivio");
+MODULE_AUTHOR("Mattias Nissler");
+MODULE_LICENSE("GPL");
+
+int __init rc80211_pid_init(void)
+{
+	return ieee80211_rate_control_register(&mac80211_rcpid);
+}
+
+void __exit rc80211_pid_exit(void)
+{
+	ieee80211_rate_control_unregister(&mac80211_rcpid);
+}
+
+#ifdef CONFIG_MAC80211_RC_PID_MODULE
+module_init(rc80211_pid_init);
+module_exit(rc80211_pid_exit);
+#endif