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);