sdio: enable wide bus mode

Enable 4-bit data bus mode, according to host and card
capabilities.
Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>

drivers/mmc/core/sdio.c

@@ -138,6 +138,32 @@ static int sdio_read_cccr(struct mmc_card *card)
 	return ret;
 }
 
+static int sdio_enable_wide(struct mmc_card *card)
+{
+	int ret;
+	u8 ctrl;
+
+	if (!(card->host->caps & MMC_CAP_4_BIT_DATA))
+		return 0;
+
+	if (card->cccr.low_speed && !card->cccr.wide_bus)
+		return 0;
+
+	ret = mmc_io_rw_direct(card, 0, 0, SDIO_CCCR_IF, 0, &ctrl);
+	if (ret)
+		return ret;
+
+	ctrl |= SDIO_BUS_WIDTH_4BIT;
+
+	ret = mmc_io_rw_direct(card, 1, 0, SDIO_CCCR_IF, ctrl, NULL);
+	if (ret)
+		return ret;
+
+	mmc_set_bus_width(card->host, MMC_BUS_WIDTH_4);
+
+	return 0;
+}
+
 /*
  * Host is being removed. Free up the current card.
  */
@@ -299,6 +325,13 @@ int mmc_attach_sdio(struct mmc_host *host, u32 ocr)
 	 */
 	mmc_set_clock(host, card->cis.max_dtr);
 
+	/*
+	 * Switch to wider bus (if supported).
+	 */
+	err = sdio_enable_wide(card);
+	if (err)
+		goto remove;
+
 	/*
 	 * Initialize (but don't add) all present functions.
 	 */