Add support for multiplexed SDIO pins from Uros

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@3898 42af7a65-404d-4744-a932-0658087f49c3

drivers/mmcsd/mmcsd_sdio.c

@@ -148,7 +148,10 @@ struct mmcsd_state_s
 /* Misc Helpers *************************************************************/
 
 static void    mmcsd_takesem(FAR struct mmcsd_state_s *priv);
-#define mmcsd_givesem(p) sem_post(&priv->sem);
+
+#ifndef CONFIG_SDIO_MUXBUS
+#  define mmcsd_givesem(p) sem_post(&priv->sem);
+#endif
 
 /* Command/response helpers *************************************************/
 
@@ -261,18 +264,41 @@ static const struct block_operations g_bops =
 
 static void mmcsd_takesem(FAR struct mmcsd_state_s *priv)
 {
-  /* Take the semaphore (perhaps waiting) */
+  /* Take the semaphore, giving exclusive access to the driver (perhaps
+   * waiting)
+   */
 
   while (sem_wait(&priv->sem) != 0)
     {
-      /* The only case that an error should occr here is if the wait was
+      /* The only case that an error should occur here is if the wait was
        * awakened by a signal.
        */
 
       ASSERT(errno == EINTR);
     }
+
+  /* Lock the bus if mutually exclusive access to the SDIO bus is required
+   * on this platform.
+   */
+  
+#ifdef CONFIG_SDIO_MUXBUS
+  SDIO_LOCK(priv->dev, TRUE);
+#endif
 }
 
+#ifdef CONFIG_SDIO_MUXBUS
+static void mmcsd_givesem(FAR struct mmcsd_state_s *priv)
+{
+  /* Release the SDIO bus lock, then the MMC/SD driver semaphore in the
+   * opposite order that they were taken to assure that no deadlock
+   * conditions will arise.
+   */
+
+  SDIO_LOCK(priv->dev, FALSE);
+  sem_post(&priv->sem);
+}
+#endif
+
 /****************************************************************************
  * Command/Response Helpers
  ****************************************************************************/