sdio: add MMC_QUIRK_LENIENT_FN0

Normally writes to SDIO function 0 outside the vendor specific CCCR
registers are prohibited.

To support embedded devices that require writes to SDIO function 0 outside
this range (e.g. TI WL127x embedded sdio wifi device),
MMC_QUIRK_LENIENT_FN0 is introduced.

A card quirks field is added to `struct mmc_card' to support non-standard
devices (e.g. embedded sdio devices).

[[e-mail]: code in C, not cpp!]
Signed-off-by: Ohad Ben-Cohen <[e-mail]>
Cc: <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

drivers/mmc/core/sdio_io.c

···
 
 	BUG_ON(!func);
 
-	if (addr < 0xF0 || addr > 0xFF) {
+	if ((addr < 0xF0 || addr > 0xFF) && (!mmc_card_lenient_fn0(func->card))) {
 		if (err_ret)
 			*err_ret = -EINVAL;
 		return;

include/linux/mmc/card.h

···
 #define MMC_STATE_READONLY	(1<<1)		/* card is read-only */
 #define MMC_STATE_HIGHSPEED	(1<<2)		/* card is in high speed mode */
 #define MMC_STATE_BLOCKADDR	(1<<3)		/* card uses block-addressing */
+	unsigned int		quirks; 	/* card quirks */
+#define MMC_QUIRK_LENIENT_FN0	(1<<0)		/* allow SDIO FN0 writes outside of the VS CCCR range */
 
 	u32			raw_cid[4];	/* raw card CID */
 	u32			raw_csd[4];	/* raw card CSD */
···
 #define mmc_card_set_readonly(c) ((c)->state |= MMC_STATE_READONLY)
 #define mmc_card_set_highspeed(c) ((c)->state |= MMC_STATE_HIGHSPEED)
 #define mmc_card_set_blockaddr(c) ((c)->state |= MMC_STATE_BLOCKADDR)
+
+static inline int mmc_card_lenient_fn0(const struct mmc_card *c)
+{
+	return c->quirks & MMC_QUIRK_LENIENT_FN0;
+}
 
 #define mmc_card_name(c)	((c)->cid.prod_name)
 #define mmc_card_id(c)		(dev_name(&(c)->dev))