spi/pl022: disable the PL022 block when unused

Make sure we clear the enable bit when the block is not used.
This will save some energy in certain hardware versions.
Reviewed-by: NViresh Kumar <viresh.kumar@st.com>
Signed-off-by: NVirupax Sadashivpetimath <virupax.sadashivpetimath@stericsson.com>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>

drivers/spi/spi-pl022.c

@@ -1512,8 +1512,12 @@ static void pump_messages(struct work_struct *work)
 	/* Lock queue and check for queue work */
 	spin_lock_irqsave(&pl022->queue_lock, flags);
 	if (list_empty(&pl022->queue) || !pl022->running) {
-		if (pl022->busy)
+		if (pl022->busy) {
+			/* nothing more to do - disable spi/ssp and power off */
+			writew((readw(SSP_CR1(pl022->virtbase)) &
+				(~SSP_CR1_MASK_SSE)), SSP_CR1(pl022->virtbase));
 			pm_runtime_put(&pl022->adev->dev);
+		}
 		pl022->busy = false;
 		spin_unlock_irqrestore(&pl022->queue_lock, flags);
 		return;