libertas: fix suspend and resume for SDIO connected cards

Prior to commit 573185cc7e ("mmc: core: Invoke sdio func driver's PM
callbacks from the sdio bus"), the MMC core used to call into the power
management functions of SDIO clients itself and removed the card if the
return code was non-zero. IOW, the mmc handled errors gracefully and didn't
upchain them to the pm core.

Since this change, the mmc core relies on generic power management
functions which treat all errors as a reason to cancel the suspend
immediately. This causes suspend attempts to fail when the libertas
driver is loaded.

To fix this, power down the card explicitly in if_sdio_suspend() when we
know we're about to lose power and return success. Also set a flag in these
cases, and power up the card again in if_sdio_resume().

Fixes: 573185cc7e ("mmc: core: Invoke sdio func driver's PM callbacks from the sdio bus")
Cc: <stable@vger.kernel.org>
Signed-off-by: Daniel Mack <daniel@zonque.org>
Reviewed-by: Chris Ball <chris@printf.net>
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/marvell/libertas/dev.h

@@ -104,6 +104,7 @@ struct lbs_private {
 	u8 fw_ready;
 	u8 surpriseremoved;
 	u8 setup_fw_on_resume;
+	u8 power_up_on_resume;
 	int (*hw_host_to_card) (struct lbs_private *priv, u8 type, u8 *payload, u16 nb);
 	void (*reset_card) (struct lbs_private *priv);
 	int (*power_save) (struct lbs_private *priv);

drivers/net/wireless/marvell/libertas/if_sdio.c

@@ -1290,15 +1290,23 @@ static void if_sdio_remove(struct sdio_func *func)
 static int if_sdio_suspend(struct device *dev)
 {
 	struct sdio_func *func = dev_to_sdio_func(dev);
-	int ret;
 	struct if_sdio_card *card = sdio_get_drvdata(func);
+	struct lbs_private *priv = card->priv;
+	int ret;
 
 	mmc_pm_flag_t flags = sdio_get_host_pm_caps(func);
+	priv->power_up_on_resume = false;
 
 	/* If we're powered off anyway, just let the mmc layer remove the
 	 * card. */
-	if (!lbs_iface_active(card->priv))
-		return -ENOSYS;
+	if (!lbs_iface_active(priv)) {
+		if (priv->fw_ready) {
+			priv->power_up_on_resume = true;
+			if_sdio_power_off(card);
+		}
+
+		return 0;
+	}
 
 	dev_info(dev, "%s: suspend: PM flags = 0x%x\n",
 		 sdio_func_id(func), flags);
@@ -1306,9 +1314,14 @@ static int if_sdio_suspend(struct device *dev)
 	/* If we aren't being asked to wake on anything, we should bail out
 	 * and let the SD stack power down the card.
 	 */
-	if (card->priv->wol_criteria == EHS_REMOVE_WAKEUP) {
+	if (priv->wol_criteria == EHS_REMOVE_WAKEUP) {
 		dev_info(dev, "Suspend without wake params -- powering down card\n");
-		return -ENOSYS;
+		if (priv->fw_ready) {
+			priv->power_up_on_resume = true;
+			if_sdio_power_off(card);
+		}
+
+		return 0;
 	}
 
 	if (!(flags & MMC_PM_KEEP_POWER)) {
@@ -1321,7 +1334,7 @@ static int if_sdio_suspend(struct device *dev)
 	if (ret)
 		return ret;
 
-	ret = lbs_suspend(card->priv);
+	ret = lbs_suspend(priv);
 	if (ret)
 		return ret;
 
@@ -1336,6 +1349,11 @@ static int if_sdio_resume(struct device *dev)
 
 	dev_info(dev, "%s: resume: we're back\n", sdio_func_id(func));
 
+	if (card->priv->power_up_on_resume) {
+		if_sdio_power_on(card);
+		wait_event(card->pwron_waitq, card->priv->fw_ready);
+	}
+
 	ret = lbs_resume(card->priv);
 
 	return ret;