mmc: add MMC_QUIRK_NONSTD_FUNC_IF

Introduce MMC_QUIRK_NONSTD_FUNC_IF to ignore the "SDIO Standard Function
interface code" as indicated by the card's FBR, and instead treat all
functions as non-standard interfaces.

This is required to prevent standard drivers from facing
errors when trying to communicate with SDIO cards that erroneously
indicate standard function interface codes.

Signed-off-by: Ohad Ben-Cohen <ohad@wizery.com>
Signed-off-by: Chris Ball <cjb@laptop.org>
diff --git a/drivers/mmc/core/sdio.c b/drivers/mmc/core/sdio.c
index 4221670..c3c2bd0 100644
--- a/drivers/mmc/core/sdio.c
+++ b/drivers/mmc/core/sdio.c
@@ -16,6 +16,7 @@
 #include <linux/mmc/card.h>
 #include <linux/mmc/sdio.h>
 #include <linux/mmc/sdio_func.h>
+#include <linux/mmc/sdio_ids.h>
 
 #include "core.h"
 #include "bus.h"
@@ -31,6 +32,11 @@
 	int ret;
 	unsigned char data;
 
+	if (mmc_card_nonstd_func_interface(func->card)) {
+		func->class = SDIO_CLASS_NONE;
+		return 0;
+	}
+
 	ret = mmc_io_rw_direct(func->card, 0, 0,
 		SDIO_FBR_BASE(func->num) + SDIO_FBR_STD_IF, 0, &data);
 	if (ret)