libertas: convert libertas driver to use an event/cmdresp queue

This patch (co-developed by Dan Williams and Holger Schurig) uses a kfifo
object for events and a swapping buffer scheme for the command response to
preserve the zero-copy semantics of the CF driver and keep memory usage low.
The main thread should only ever touch the buffer indexed by priv->resp_idx,
while the interface code is free to write to the second buffer, then swap
priv->resp_idx under the driver spinlock.  The firmware specs only permit
one in-flight command, so there will only ever be one command response to
process at a time.

Signed-off-by: Holger Schurig <hs4233@mail.mn-solutions.de>
Signed-off-by: Dan Williams <dcbw@redhat.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 17 insertions, 8 deletions

diff --git a/drivers/net/wireless/libertas/cmd.c b/drivers/net/wireless/libertas/cmd.c
index 4a82f5114ca0..49267ed7cea3 100644
--- a/drivers/net/wireless/libertas/cmd.c
+++ b/drivers/net/wireless/libertas/cmd.c
@@ -4,6 +4,7 @@
   */
 
 #include <net/iw_handler.h>
+#include <linux/kfifo.h>
 #include "host.h"
 #include "hostcmd.h"
 #include "decl.h"
@@ -1829,15 +1830,20 @@ static void lbs_send_confirmsleep(struct lbs_private *priv)
 
 	ret = priv->hw_host_to_card(priv, MVMS_CMD, (u8 *) &confirm_sleep,
 		sizeof(confirm_sleep));
-
 	if (ret) {
 		lbs_pr_alert("confirm_sleep failed\n");
-	} else {
-		spin_lock_irqsave(&priv->driver_lock, flags);
-		if (!priv->intcounter)
-			priv->psstate = PS_STATE_SLEEP;
-		spin_unlock_irqrestore(&priv->driver_lock, flags);
+		goto out;
 	}
+
+	spin_lock_irqsave(&priv->driver_lock, flags);
+
+	/* If nothing to do, go back to sleep (?) */
+	if (!__kfifo_len(priv->event_fifo) && !priv->resp_len[priv->resp_idx])
+		priv->psstate = PS_STATE_SLEEP;
+
+	spin_unlock_irqrestore(&priv->driver_lock, flags);
+
+out:
 	lbs_deb_leave(LBS_DEB_HOST);
 }
 
@@ -1899,13 +1905,16 @@ void lbs_ps_confirm_sleep(struct lbs_private *priv)
 	}
 
 	spin_lock_irqsave(&priv->driver_lock, flags);
+	/* In-progress command? */
 	if (priv->cur_cmd) {
 		allowed = 0;
 		lbs_deb_host("cur_cmd was set\n");
 	}
-	if (priv->intcounter > 0) {
+
+	/* Pending events or command responses? */
+	if (__kfifo_len(priv->event_fifo) || priv->resp_len[priv->resp_idx]) {
 		allowed = 0;
-		lbs_deb_host("intcounter %d\n", priv->intcounter);
+		lbs_deb_host("pending events or command responses\n");
 	}
 	spin_unlock_irqrestore(&priv->driver_lock, flags);