mmc: core: Put eMMC in Sleep mode before suspend

Put MMC to sleep if it supports SLEEP/AWAKE (CMD5) in the mmc suspend
so that Vcc (NAND core) can be cut to minimize power consumption.
eMMC put into SLEEP can respond to CMD0 or H/W reset or CMD5.
Current implemention on resume from suspend relies on CMD0 in
mmc_init_card to get out of SLEEP mode.

Signed-off-by: Balaji T K <balajitk@ti.com>
Acked-by: Venkatraman S <svenkatr@ti.com>
Reviewed-by: Subhash Jadavani <subhashj@codeaurora.org>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Chris Ball <cjb@laptop.org>

drivers/mmc/core/mmc.c

@@ -553,6 +553,7 @@ static int mmc_init_card(struct mmc_host *host, u32 ocr,
 	 * need to tell some cards to go back to the idle
 	 * state.  We wait 1ms to give cards time to
 	 * respond.
+	 * mmc_go_idle is needed for eMMC that are asleep
 	 */
 	mmc_go_idle(host);
 
@@ -900,16 +901,20 @@ static void mmc_detect(struct mmc_host *host)
  */
 static int mmc_suspend(struct mmc_host *host)
 {
+	int err = 0;
+
 	BUG_ON(!host);
 	BUG_ON(!host->card);
 
 	mmc_claim_host(host);
-	if (!mmc_host_is_spi(host))
+	if (mmc_card_can_sleep(host))
+		err = mmc_card_sleep(host);
+	else if (!mmc_host_is_spi(host))
 		mmc_deselect_cards(host);
 	host->card->state &= ~MMC_STATE_HIGHSPEED;
 	mmc_release_host(host);
 
-	return 0;
+	return err;
 }
 
 /*