mmc: add bus handler

Delegate protocol handling to "bus handlers". This allows the core to
just handle the task of arbitrating the bus. Initialisation and
pampering of cards is now done by the different bus handlers.

This design also allows MMC and SD (and later SDIO) to be more cleanly
separated, allowing easier maintenance.

Signed-off-by: Pierre Ossman <[e-mail]>

drivers/mmc/core/Makefile

···
 endif
 
 obj-$(CONFIG_MMC)		+= mmc_core.o
-mmc_core-y			:= core.o sysfs.o mmc_ops.o sd_ops.o
+mmc_core-y			:= core.o sysfs.o mmc.o mmc_ops.o sd.o sd_ops.o
 

drivers/mmc/core/core.c

···
 #include "mmc_ops.h"
 #include "sd_ops.h"
 
-#define CMD_RETRIES	3
-
-/*
- * OCR Bit positions to 10s of Vdd mV.
- */
-static const unsigned short mmc_ocr_bit_to_vdd[] = {
-	150,	155,	160,	165,	170,	180,	190,	200,
-	210,	220,	230,	240,	250,	260,	270,	280,
-	290,	300,	310,	320,	330,	340,	350,	360
-};
-
-static const unsigned int tran_exp[] = {
-	10000,		100000,		1000000,	10000000,
-	0,		0,		0,		0
-};
-
-static const unsigned char tran_mant[] = {
-	0,	10,	12,	13,	15,	20,	25,	30,
-	35,	40,	45,	50,	55,	60,	70,	80,
-};
-
-static const unsigned int tacc_exp[] = {
-	1,	10,	100,	1000,	10000,	100000,	1000000, 10000000,
-};
-
-static const unsigned int tacc_mant[] = {
-	0,	10,	12,	13,	15,	20,	25,	30,
-	35,	40,	45,	50,	55,	60,	70,	80,
-};
-
+extern int mmc_attach_mmc(struct mmc_host *host, u32 ocr);
+extern int mmc_attach_sd(struct mmc_host *host, u32 ocr);
 
 /**
  *	mmc_request_done - finish processing an MMC request
···
 
 EXPORT_SYMBOL(mmc_release_host);
 
+/*
+ * Internal function that does the actual ios call to the host driver,
+ * optionally printing some debug output.
+ */
 static inline void mmc_set_ios(struct mmc_host *host)
 {
 	struct mmc_ios *ios = &host->ios;
···
 	host->ops->set_ios(host, ios);
 }
 
+/*
+ * Control chip select pin on a host.
+ */
 void mmc_set_chip_select(struct mmc_host *host, int mode)
 {
 	host->ios.chip_select = mode;
···
 }
 
 /*
+ * Sets the host clock to the highest possible frequency that
+ * is below "hz".
+ */
+void mmc_set_clock(struct mmc_host *host, unsigned int hz)
+{
+	WARN_ON(hz < host->f_min);
+
+	if (hz > host->f_max)
+		hz = host->f_max;
+
+	host->ios.clock = hz;
+	mmc_set_ios(host);
+}
+
+/*
+ * Change the bus mode (open drain/push-pull) of a host.
+ */
+void mmc_set_bus_mode(struct mmc_host *host, unsigned int mode)
+{
+	host->ios.bus_mode = mode;
+	mmc_set_ios(host);
+}
+
+/*
+ * Change data bus width of a host.
+ */
+void mmc_set_bus_width(struct mmc_host *host, unsigned int width)
+{
+	host->ios.bus_width = width;
+	mmc_set_ios(host);
+}
+
+/*
  * Mask off any voltages we don't support and select
  * the lowest voltage
  */
-static u32 mmc_select_voltage(struct mmc_host *host, u32 ocr)
+u32 mmc_select_voltage(struct mmc_host *host, u32 ocr)
 {
 	int bit;
 
···
 	return ocr;
 }
 
-#define UNSTUFF_BITS(resp,start,size)					\
-	({								\
-		const int __size = size;				\
-		const u32 __mask = (__size < 32 ? 1 << __size : 0) - 1;	\
-		const int __off = 3 - ((start) / 32);			\
-		const int __shft = (start) & 31;			\
-		u32 __res;						\
-									\
-		__res = resp[__off] >> __shft;				\
-		if (__size + __shft > 32)				\
-			__res |= resp[__off-1] << ((32 - __shft) % 32);	\
-		__res & __mask;						\
-	})
-
 /*
- * Given the decoded CSD structure, decode the raw CID to our CID structure.
+ * Select timing parameters for host.
  */
-static void mmc_decode_cid(struct mmc_card *card)
+void mmc_set_timing(struct mmc_host *host, unsigned int timing)
 {
-	u32 *resp = card->raw_cid;
-
-	memset(&card->cid, 0, sizeof(struct mmc_cid));
-
-	if (mmc_card_sd(card)) {
-		/*
-		 * SD doesn't currently have a version field so we will
-		 * have to assume we can parse this.
-		 */
-		card->cid.manfid		= UNSTUFF_BITS(resp, 120, 8);
-		card->cid.oemid			= UNSTUFF_BITS(resp, 104, 16);
-		card->cid.prod_name[0]		= UNSTUFF_BITS(resp, 96, 8);
-		card->cid.prod_name[1]		= UNSTUFF_BITS(resp, 88, 8);
-		card->cid.prod_name[2]		= UNSTUFF_BITS(resp, 80, 8);
-		card->cid.prod_name[3]		= UNSTUFF_BITS(resp, 72, 8);
-		card->cid.prod_name[4]		= UNSTUFF_BITS(resp, 64, 8);
-		card->cid.hwrev			= UNSTUFF_BITS(resp, 60, 4);
-		card->cid.fwrev			= UNSTUFF_BITS(resp, 56, 4);
-		card->cid.serial		= UNSTUFF_BITS(resp, 24, 32);
-		card->cid.year			= UNSTUFF_BITS(resp, 12, 8);
-		card->cid.month			= UNSTUFF_BITS(resp, 8, 4);
-
-		card->cid.year += 2000; /* SD cards year offset */
-	} else {
-		/*
-		 * The selection of the format here is based upon published
-		 * specs from sandisk and from what people have reported.
-		 */
-		switch (card->csd.mmca_vsn) {
-		case 0: /* MMC v1.0 - v1.2 */
-		case 1: /* MMC v1.4 */
-			card->cid.manfid	= UNSTUFF_BITS(resp, 104, 24);
-			card->cid.prod_name[0]	= UNSTUFF_BITS(resp, 96, 8);
-			card->cid.prod_name[1]	= UNSTUFF_BITS(resp, 88, 8);
-			card->cid.prod_name[2]	= UNSTUFF_BITS(resp, 80, 8);
-			card->cid.prod_name[3]	= UNSTUFF_BITS(resp, 72, 8);
-			card->cid.prod_name[4]	= UNSTUFF_BITS(resp, 64, 8);
-			card->cid.prod_name[5]	= UNSTUFF_BITS(resp, 56, 8);
-			card->cid.prod_name[6]	= UNSTUFF_BITS(resp, 48, 8);
-			card->cid.hwrev		= UNSTUFF_BITS(resp, 44, 4);
-			card->cid.fwrev		= UNSTUFF_BITS(resp, 40, 4);
-			card->cid.serial	= UNSTUFF_BITS(resp, 16, 24);
-			card->cid.month		= UNSTUFF_BITS(resp, 12, 4);
-			card->cid.year		= UNSTUFF_BITS(resp, 8, 4) + 1997;
-			break;
-
-		case 2: /* MMC v2.0 - v2.2 */
-		case 3: /* MMC v3.1 - v3.3 */
-		case 4: /* MMC v4 */
-			card->cid.manfid	= UNSTUFF_BITS(resp, 120, 8);
-			card->cid.oemid		= UNSTUFF_BITS(resp, 104, 16);
-			card->cid.prod_name[0]	= UNSTUFF_BITS(resp, 96, 8);
-			card->cid.prod_name[1]	= UNSTUFF_BITS(resp, 88, 8);
-			card->cid.prod_name[2]	= UNSTUFF_BITS(resp, 80, 8);
-			card->cid.prod_name[3]	= UNSTUFF_BITS(resp, 72, 8);
-			card->cid.prod_name[4]	= UNSTUFF_BITS(resp, 64, 8);
-			card->cid.prod_name[5]	= UNSTUFF_BITS(resp, 56, 8);
-			card->cid.serial	= UNSTUFF_BITS(resp, 16, 32);
-			card->cid.month		= UNSTUFF_BITS(resp, 12, 4);
-			card->cid.year		= UNSTUFF_BITS(resp, 8, 4) + 1997;
-			break;
-
-		default:
-			printk("%s: card has unknown MMCA version %d\n",
-				mmc_hostname(card->host), card->csd.mmca_vsn);
-			mmc_card_set_bad(card);
-			break;
-		}
-	}
-}
-
-/*
- * Given a 128-bit response, decode to our card CSD structure.
- */
-static void mmc_decode_csd(struct mmc_card *card)
-{
-	struct mmc_csd *csd = &card->csd;
-	unsigned int e, m, csd_struct;
-	u32 *resp = card->raw_csd;
-
-	if (mmc_card_sd(card)) {
-		csd_struct = UNSTUFF_BITS(resp, 126, 2);
-
-		switch (csd_struct) {
-		case 0:
-			m = UNSTUFF_BITS(resp, 115, 4);
-			e = UNSTUFF_BITS(resp, 112, 3);
-			csd->tacc_ns	 = (tacc_exp[e] * tacc_mant[m] + 9) / 10;
-			csd->tacc_clks	 = UNSTUFF_BITS(resp, 104, 8) * 100;
-
-			m = UNSTUFF_BITS(resp, 99, 4);
-			e = UNSTUFF_BITS(resp, 96, 3);
-			csd->max_dtr	  = tran_exp[e] * tran_mant[m];
-			csd->cmdclass	  = UNSTUFF_BITS(resp, 84, 12);
-
-			e = UNSTUFF_BITS(resp, 47, 3);
-			m = UNSTUFF_BITS(resp, 62, 12);
-			csd->capacity	  = (1 + m) << (e + 2);
-
-			csd->read_blkbits = UNSTUFF_BITS(resp, 80, 4);
-			csd->read_partial = UNSTUFF_BITS(resp, 79, 1);
-			csd->write_misalign = UNSTUFF_BITS(resp, 78, 1);
-			csd->read_misalign = UNSTUFF_BITS(resp, 77, 1);
-			csd->r2w_factor = UNSTUFF_BITS(resp, 26, 3);
-			csd->write_blkbits = UNSTUFF_BITS(resp, 22, 4);
-			csd->write_partial = UNSTUFF_BITS(resp, 21, 1);
-			break;
-		case 1:
-			/*
-			 * This is a block-addressed SDHC card. Most
-			 * interesting fields are unused and have fixed
-			 * values. To avoid getting tripped by buggy cards,
-			 * we assume those fixed values ourselves.
-			 */
-			mmc_card_set_blockaddr(card);
-
-			csd->tacc_ns	 = 0; /* Unused */
-			csd->tacc_clks	 = 0; /* Unused */
-
-			m = UNSTUFF_BITS(resp, 99, 4);
-			e = UNSTUFF_BITS(resp, 96, 3);
-			csd->max_dtr	  = tran_exp[e] * tran_mant[m];
-			csd->cmdclass	  = UNSTUFF_BITS(resp, 84, 12);
-
-			m = UNSTUFF_BITS(resp, 48, 22);
-			csd->capacity     = (1 + m) << 10;
-
-			csd->read_blkbits = 9;
-			csd->read_partial = 0;
-			csd->write_misalign = 0;
-			csd->read_misalign = 0;
-			csd->r2w_factor = 4; /* Unused */
-			csd->write_blkbits = 9;
-			csd->write_partial = 0;
-			break;
-		default:
-			printk("%s: unrecognised CSD structure version %d\n",
-				mmc_hostname(card->host), csd_struct);
-			mmc_card_set_bad(card);
-			return;
-		}
-	} else {
-		/*
-		 * We only understand CSD structure v1.1 and v1.2.
-		 * v1.2 has extra information in bits 15, 11 and 10.
-		 */
-		csd_struct = UNSTUFF_BITS(resp, 126, 2);
-		if (csd_struct != 1 && csd_struct != 2) {
-			printk("%s: unrecognised CSD structure version %d\n",
-				mmc_hostname(card->host), csd_struct);
-			mmc_card_set_bad(card);
-			return;
-		}
-
-		csd->mmca_vsn	 = UNSTUFF_BITS(resp, 122, 4);
-		m = UNSTUFF_BITS(resp, 115, 4);
-		e = UNSTUFF_BITS(resp, 112, 3);
-		csd->tacc_ns	 = (tacc_exp[e] * tacc_mant[m] + 9) / 10;
-		csd->tacc_clks	 = UNSTUFF_BITS(resp, 104, 8) * 100;
-
-		m = UNSTUFF_BITS(resp, 99, 4);
-		e = UNSTUFF_BITS(resp, 96, 3);
-		csd->max_dtr	  = tran_exp[e] * tran_mant[m];
-		csd->cmdclass	  = UNSTUFF_BITS(resp, 84, 12);
-
-		e = UNSTUFF_BITS(resp, 47, 3);
-		m = UNSTUFF_BITS(resp, 62, 12);
-		csd->capacity	  = (1 + m) << (e + 2);
-
-		csd->read_blkbits = UNSTUFF_BITS(resp, 80, 4);
-		csd->read_partial = UNSTUFF_BITS(resp, 79, 1);
-		csd->write_misalign = UNSTUFF_BITS(resp, 78, 1);
-		csd->read_misalign = UNSTUFF_BITS(resp, 77, 1);
-		csd->r2w_factor = UNSTUFF_BITS(resp, 26, 3);
-		csd->write_blkbits = UNSTUFF_BITS(resp, 22, 4);
-		csd->write_partial = UNSTUFF_BITS(resp, 21, 1);
-	}
-}
-
-/*
- * Given a 64-bit response, decode to our card SCR structure.
- */
-static void mmc_decode_scr(struct mmc_card *card)
-{
-	struct sd_scr *scr = &card->scr;
-	unsigned int scr_struct;
-	u32 resp[4];
-
-	BUG_ON(!mmc_card_sd(card));
-
-	resp[3] = card->raw_scr[1];
-	resp[2] = card->raw_scr[0];
-
-	scr_struct = UNSTUFF_BITS(resp, 60, 4);
-	if (scr_struct != 0) {
-		printk("%s: unrecognised SCR structure version %d\n",
-			mmc_hostname(card->host), scr_struct);
-		mmc_card_set_bad(card);
-		return;
-	}
-
-	scr->sda_vsn = UNSTUFF_BITS(resp, 56, 4);
-	scr->bus_widths = UNSTUFF_BITS(resp, 48, 4);
+	host->ios.timing = timing;
+	mmc_set_ios(host);
 }
 
 /*
  * Allocate a new MMC card
  */
-static struct mmc_card *
-mmc_alloc_card(struct mmc_host *host, u32 *raw_cid)
+struct mmc_card *mmc_alloc_card(struct mmc_host *host)
 {
 	struct mmc_card *card;
 
···
 		return ERR_PTR(-ENOMEM);
 
 	mmc_init_card(card, host);
-	memcpy(card->raw_cid, raw_cid, sizeof(card->raw_cid));
 
 	return card;
 }
···
 }
 
 /*
- * Discover the card by requesting its CID.
- *
- * Create a mmc_card entry for the discovered card, assigning
- * it an RCA, and save the raw CID for decoding later.
+ * Assign a mmc bus handler to a host. Only one bus handler may control a
+ * host at any given time.
  */
-static void mmc_discover_card(struct mmc_host *host)
+void mmc_attach_bus(struct mmc_host *host, const struct mmc_bus_ops *ops)
 {
-	unsigned int err;
-	u32 cid[4];
+	unsigned long flags;
 
-	BUG_ON(host->card);
+	BUG_ON(!host);
+	BUG_ON(!ops);
 
-	err = mmc_all_send_cid(host, cid);
-	if (err != MMC_ERR_NONE) {
-		printk(KERN_ERR "%s: error requesting CID: %d\n",
-			mmc_hostname(host), err);
-		return;
-	}
+	BUG_ON(!host->claimed);
 
-	host->card = mmc_alloc_card(host, cid);
-	if (IS_ERR(host->card)) {
-		err = PTR_ERR(host->card);
-		host->card = NULL;
-		return;
-	}
+	spin_lock_irqsave(&host->lock, flags);
 
-	if (host->mode == MMC_MODE_SD) {
-		host->card->type = MMC_TYPE_SD;
+	BUG_ON(host->bus_ops);
+	BUG_ON(host->bus_refs);
 
-		err = mmc_send_relative_addr(host, &host->card->rca);
-		if (err != MMC_ERR_NONE)
-			mmc_card_set_dead(host->card);
-		else {
-			if (!host->ops->get_ro) {
-				printk(KERN_WARNING "%s: host does not "
-					"support reading read-only "
-					"switch. assuming write-enable.\n",
-					mmc_hostname(host));
-			} else {
-				if (host->ops->get_ro(host))
-					mmc_card_set_readonly(host->card);
-			}
-		}
-	} else {
-		host->card->type = MMC_TYPE_MMC;
-		host->card->rca = 1;
+	host->bus_ops = ops;
+	host->bus_refs = 1;
+	host->bus_dead = 0;
 
-		err = mmc_set_relative_addr(host->card);
-		if (err != MMC_ERR_NONE)
-			mmc_card_set_dead(host->card);
-	}
-}
-
-static void mmc_read_csd(struct mmc_host *host)
-{
-	int err;
-
-	if (!host->card)
-		return;
-	if (mmc_card_dead(host->card))
-		return;
-
-	err = mmc_send_csd(host->card, host->card->raw_csd);
-	if (err != MMC_ERR_NONE) {
-		mmc_card_set_dead(host->card);
-		return;
-	}
-
-	mmc_decode_csd(host->card);
-	mmc_decode_cid(host->card);
-}
-
-static void mmc_process_ext_csd(struct mmc_host *host)
-{
-	int err;
-	u8 *ext_csd;
-
-	if (!host->card)
-		return;
-	if (mmc_card_dead(host->card))
-		return;
-	if (mmc_card_sd(host->card))
-		return;
-	if (host->card->csd.mmca_vsn < CSD_SPEC_VER_4)
-		return;
-
-	/*
-	 * As the ext_csd is so large and mostly unused, we don't store the
-	 * raw block in mmc_card.
-	 */
-	ext_csd = kmalloc(512, GFP_KERNEL);
-	if (!ext_csd) {
-		printk("%s: could not allocate a buffer to receive the ext_csd."
-		       "mmc v4 cards will be treated as v3.\n",
-			mmc_hostname(host));
-		return;
-	}
-
-	err = mmc_send_ext_csd(host->card, ext_csd);
-	if (err != MMC_ERR_NONE) {
-		if (host->card->csd.capacity == (4096 * 512)) {
-			printk(KERN_ERR "%s: unable to read EXT_CSD "
-				"on a possible high capacity card. "
-				"Card will be ignored.\n",
-				mmc_hostname(host));
-			mmc_card_set_dead(host->card);
-		} else {
-			printk(KERN_WARNING "%s: unable to read "
-				"EXT_CSD, performance might "
-				"suffer.\n",
-				mmc_hostname(host));
-		}
-		goto out;
-	}
-
-	host->card->ext_csd.sectors =
-		ext_csd[EXT_CSD_SEC_CNT + 0] << 0 |
-		ext_csd[EXT_CSD_SEC_CNT + 1] << 8 |
-		ext_csd[EXT_CSD_SEC_CNT + 2] << 16 |
-		ext_csd[EXT_CSD_SEC_CNT + 3] << 24;
-	if (host->card->ext_csd.sectors)
-		mmc_card_set_blockaddr(host->card);
-
-	switch (ext_csd[EXT_CSD_CARD_TYPE]) {
-	case EXT_CSD_CARD_TYPE_52 | EXT_CSD_CARD_TYPE_26:
-		host->card->ext_csd.hs_max_dtr = 52000000;
-		break;
-	case EXT_CSD_CARD_TYPE_26:
-		host->card->ext_csd.hs_max_dtr = 26000000;
-		break;
-	default:
-		/* MMC v4 spec says this cannot happen */
-		printk("%s: card is mmc v4 but doesn't support "
-		       "any high-speed modes.\n",
-			mmc_hostname(host));
-		goto out;
-	}
-
-	if (host->caps & MMC_CAP_MMC_HIGHSPEED) {
-		/* Activate highspeed support. */
-		err = mmc_switch(host->card, MMC_SWITCH_MODE_WRITE_BYTE,
-			EXT_CSD_HS_TIMING, 1);
-		if (err != MMC_ERR_NONE) {
-			printk("%s: failed to switch card to mmc v4 "
-			       "high-speed mode.\n",
-			       mmc_hostname(host));
-			goto out;
-		}
-
-		mmc_card_set_highspeed(host->card);
-
-		host->ios.timing = MMC_TIMING_MMC_HS;
-		mmc_set_ios(host);
-	}
-
-	/* Check for host support for wide-bus modes. */
-	if (host->caps & MMC_CAP_4_BIT_DATA) {
-		/* Activate 4-bit support. */
-		err = mmc_switch(host->card, MMC_SWITCH_MODE_WRITE_BYTE,
-			EXT_CSD_BUS_WIDTH, EXT_CSD_BUS_WIDTH_4 |
-			EXT_CSD_CMD_SET_NORMAL);
-		if (err != MMC_ERR_NONE) {
-			printk("%s: failed to switch card to "
-			       "mmc v4 4-bit bus mode.\n",
-			       mmc_hostname(host));
-			goto out;
-		}
-
-		host->ios.bus_width = MMC_BUS_WIDTH_4;
-		mmc_set_ios(host);
-	}
-
-out:
-	kfree(ext_csd);
-}
-
-static void mmc_read_scr(struct mmc_host *host)
-{
-	int err;
-
-	if (!host->card)
-		return;
-	if (mmc_card_dead(host->card))
-		return;
-	if (!mmc_card_sd(host->card))
-		return;
-
-	err = mmc_app_send_scr(host->card, host->card->raw_scr);
-	if (err != MMC_ERR_NONE) {
-		mmc_card_set_dead(host->card);
-		return;
-	}
-
-	mmc_decode_scr(host->card);
-}
-
-static void mmc_read_switch_caps(struct mmc_host *host)
-{
-	int err;
-	unsigned char *status;
-
-	if (!(host->caps & MMC_CAP_SD_HIGHSPEED))
-		return;
-
-	if (!host->card)
-		return;
-	if (mmc_card_dead(host->card))
-		return;
-	if (!mmc_card_sd(host->card))
-		return;
-	if (host->card->scr.sda_vsn < SCR_SPEC_VER_1)
-		return;
-
-	status = kmalloc(64, GFP_KERNEL);
-	if (!status) {
-		printk(KERN_WARNING "%s: Unable to allocate buffer for "
-			"reading switch capabilities.\n",
-			mmc_hostname(host));
-		return;
-	}
-
-	err = mmc_sd_switch(host->card, SD_SWITCH_CHECK,
-		SD_SWITCH_GRP_ACCESS, SD_SWITCH_ACCESS_HS, status);
-	if (err != MMC_ERR_NONE) {
-		printk("%s: unable to read switch capabilities, "
-			"performance might suffer.\n",
-			mmc_hostname(host));
-		goto out;
-	}
-
-	if (status[13] & 0x02)
-		host->card->sw_caps.hs_max_dtr = 50000000;
-
-	err = mmc_sd_switch(host->card, SD_SWITCH_SET,
-		SD_SWITCH_GRP_ACCESS, SD_SWITCH_ACCESS_HS, status);
-	if (err != MMC_ERR_NONE || (status[16] & 0xF) != 1) {
-		printk(KERN_WARNING "%s: Problem switching card "
-			"into high-speed mode!\n",
-			mmc_hostname(host));
-		goto out;
-	}
-
-	mmc_card_set_highspeed(host->card);
-
-	host->ios.timing = MMC_TIMING_SD_HS;
-	mmc_set_ios(host);
-
-out:
-	kfree(status);
-}
-
-static unsigned int mmc_calculate_clock(struct mmc_host *host)
-{
-	unsigned int max_dtr = host->f_max;
-
-	if (host->card && !mmc_card_dead(host->card)) {
-		if (mmc_card_highspeed(host->card) && mmc_card_sd(host->card)) {
-			if (max_dtr > host->card->sw_caps.hs_max_dtr)
-				max_dtr = host->card->sw_caps.hs_max_dtr;
-		} else if (mmc_card_highspeed(host->card) && !mmc_card_sd(host->card)) {
-			if (max_dtr > host->card->ext_csd.hs_max_dtr)
-				max_dtr = host->card->ext_csd.hs_max_dtr;
-		} else if (max_dtr > host->card->csd.max_dtr) {
-			max_dtr = host->card->csd.max_dtr;
-		}
-	}
-
-	pr_debug("%s: selected %d.%03dMHz transfer rate\n",
-		 mmc_hostname(host),
-		 max_dtr / 1000000, (max_dtr / 1000) % 1000);
-
-	return max_dtr;
+	spin_unlock_irqrestore(&host->lock, flags);
 }
 
 /*
- * Check whether cards we already know about are still present.
- * We do this by requesting status, and checking whether a card
- * responds.
- *
- * A request for status does not cause a state change in data
- * transfer mode.
+ * Remove the current bus handler from a host. Assumes that there are
+ * no interesting cards left, so the bus is powered down.
  */
-static void mmc_check_card(struct mmc_card *card)
+void mmc_detach_bus(struct mmc_host *host)
 {
-	int err;
+	unsigned long flags;
 
-	BUG_ON(!card);
+	BUG_ON(!host);
 
-	err = mmc_send_status(card, NULL);
-	if (err == MMC_ERR_NONE)
-		return;
+	BUG_ON(!host->claimed);
+	BUG_ON(!host->bus_ops);
 
-	mmc_card_set_dead(card);
+	spin_lock_irqsave(&host->lock, flags);
+
+	host->bus_dead = 1;
+
+	spin_unlock_irqrestore(&host->lock, flags);
+
+	mmc_power_off(host);
+
+	mmc_bus_put(host);
 }
 
-static void mmc_setup(struct mmc_host *host)
+/*
+ * Cleanup when the last reference to the bus operator is dropped.
+ */
+void __mmc_release_bus(struct mmc_host *host)
 {
-	int err;
-	u32 ocr;
+	BUG_ON(!host);
+	BUG_ON(host->bus_refs);
+	BUG_ON(!host->bus_dead);
 
-	host->mode = MMC_MODE_SD;
-
-	mmc_power_up(host);
-	mmc_go_idle(host);
-
-	err = mmc_send_if_cond(host, host->ocr_avail);
-	if (err != MMC_ERR_NONE) {
-		return;
-	}
-	err = mmc_send_app_op_cond(host, 0, &ocr);
-
-	/*
-	 * If we fail to detect any SD cards then try
-	 * searching for MMC cards.
-	 */
-	if (err != MMC_ERR_NONE) {
-		host->mode = MMC_MODE_MMC;
-
-		err = mmc_send_op_cond(host, 0, &ocr);
-		if (err != MMC_ERR_NONE)
-			return;
-	}
-
-	host->ocr = mmc_select_voltage(host, ocr);
-
-	if (host->ocr == 0)
-		return;
-
-	/*
-	 * Since we're changing the OCR value, we seem to
-	 * need to tell some cards to go back to the idle
-	 * state.  We wait 1ms to give cards time to
-	 * respond.
-	 */
-	mmc_go_idle(host);
-
-	/*
-	 * Send the selected OCR multiple times... until the cards
-	 * all get the idea that they should be ready for CMD2.
-	 * (My SanDisk card seems to need this.)
-	 */
-	if (host->mode == MMC_MODE_SD) {
-		/*
-		 * If SD_SEND_IF_COND indicates an SD 2.0
-		 * compliant card and we should set bit 30
-		 * of the ocr to indicate that we can handle
-		 * block-addressed SDHC cards.
-		 */
-		err = mmc_send_if_cond(host, host->ocr);
-		if (err == MMC_ERR_NONE)
-			ocr = host->ocr | (1 << 30);
-
-		mmc_send_app_op_cond(host, ocr, NULL);
-	} else {
-		/* The extra bit indicates that we support high capacity */
-		mmc_send_op_cond(host, host->ocr | (1 << 30), NULL);
-	}
-
-	mmc_discover_card(host);
-
-	/*
-	 * Ok, now switch to push-pull mode.
-	 */
-	host->ios.bus_mode = MMC_BUSMODE_PUSHPULL;
-	mmc_set_ios(host);
-
-	mmc_read_csd(host);
-
-	if (host->card && !mmc_card_dead(host->card)) {
-		err = mmc_select_card(host->card);
-		if (err != MMC_ERR_NONE)
-			mmc_card_set_dead(host->card);
-	}
-
-	/*
-	 * The card is in 1 bit mode by default so
-	 * we only need to change if it supports the
-	 * wider version.
-	 */
-	if (host->card && !mmc_card_dead(host->card) && 
-		mmc_card_sd(host->card) &&
-		(host->card->scr.bus_widths & SD_SCR_BUS_WIDTH_4) &&
-		(host->card->host->caps & MMC_CAP_4_BIT_DATA)) {
-		err = mmc_app_set_bus_width(host->card, SD_BUS_WIDTH_4);
-		if (err != MMC_ERR_NONE)
-			mmc_card_set_dead(host->card);
-		else {
-			host->ios.bus_width = MMC_BUS_WIDTH_4;
-			mmc_set_ios(host);
-		}
-	}
-
-	if (host->mode == MMC_MODE_SD) {
-		mmc_read_scr(host);
-		mmc_read_switch_caps(host);
-	} else
-		mmc_process_ext_csd(host);
+	host->bus_ops = NULL;
 }
-
 
 /**
  *	mmc_detect_change - process change of state on a MMC socket
···
 {
 	struct mmc_host *host =
 		container_of(work, struct mmc_host, detect.work);
+	u32 ocr;
+	int err;
 
-	mmc_claim_host(host);
+	mmc_bus_get(host);
 
-	/*
-	 * Check for removed card and newly inserted ones. We check for
-	 * removed cards first so we can intelligently re-select the VDD.
-	 */
-	if (host->card) {
-		mmc_check_card(host->card);
-
-		mmc_release_host(host);
-
-		if (mmc_card_dead(host->card)) {
-			mmc_remove_card(host->card);
-			host->card = NULL;
-		}
-
-		goto out;
-	}
-
-	mmc_setup(host);
-
-	if (host->card && !mmc_card_dead(host->card)) {
+	if (host->bus_ops == NULL) {
 		/*
-		 * (Re-)calculate the fastest clock rate which the
-		 * attached cards and the host support.
+		 * Only we can add a new handler, so it's safe to
+		 * release the lock here.
 		 */
-		host->ios.clock = mmc_calculate_clock(host);
-		mmc_set_ios(host);
+		mmc_bus_put(host);
+
+		mmc_claim_host(host);
+
+		mmc_power_up(host);
+		mmc_go_idle(host);
+
+		mmc_send_if_cond(host, host->ocr_avail);
+
+		err = mmc_send_app_op_cond(host, 0, &ocr);
+		if (err == MMC_ERR_NONE) {
+			if (mmc_attach_sd(host, ocr))
+				mmc_power_off(host);
+		} else {
+			/*
+			 * If we fail to detect any SD cards then try
+			 * searching for MMC cards.
+			 */
+			err = mmc_send_op_cond(host, 0, &ocr);
+			if (err == MMC_ERR_NONE) {
+				if (mmc_attach_mmc(host, ocr))
+					mmc_power_off(host);
+			} else {
+				mmc_power_off(host);
+				mmc_release_host(host);
+			}
+		}
+	} else {
+		if (host->bus_ops->detect && !host->bus_dead)
+			host->bus_ops->detect(host);
+
+		mmc_bus_put(host);
 	}
-
-	mmc_release_host(host);
-
-	/*
-	 * If this is a new and good card, register it.
-	 */
-	if (host->card && !mmc_card_dead(host->card)) {
-		if (mmc_register_card(host->card))
-			mmc_card_set_dead(host->card);
-	}
-
-	/*
-	 * If this card is dead, destroy it.
-	 */
-	if (host->card && mmc_card_dead(host->card)) {
-		mmc_remove_card(host->card);
-		host->card = NULL;
-	}
-
-out:
-	/*
-	 * If we discover that there are no cards on the
-	 * bus, turn off the clock and power down.
-	 */
-	if (!host->card)
-		mmc_power_off(host);
 }
 
 
···
 
 	mmc_flush_scheduled_work();
 
-	if (host->card) {
-		mmc_remove_card(host->card);
-		host->card = NULL;
+	mmc_bus_get(host);
+	if (host->bus_ops && !host->bus_dead) {
+		if (host->bus_ops->remove)
+			host->bus_ops->remove(host);
+
+		mmc_claim_host(host);
+		mmc_detach_bus(host);
+		mmc_release_host(host);
 	}
+	mmc_bus_put(host);
+
+	BUG_ON(host->card);
 
 	mmc_power_off(host);
 	mmc_remove_host_sysfs(host);
···
 {
 	mmc_flush_scheduled_work();
 
-	if (host->card) {
-		mmc_remove_card(host->card);
-		host->card = NULL;
+	mmc_bus_get(host);
+	if (host->bus_ops && !host->bus_dead) {
+		if (host->bus_ops->remove)
+			host->bus_ops->remove(host);
+		mmc_detach_bus(host);
 	}
+	mmc_bus_put(host);
+
+	BUG_ON(host->card);
 
 	mmc_power_off(host);
 

drivers/mmc/core/core.h

···
 
 #define MMC_CMD_RETRIES        3
 
+struct mmc_bus_ops {
+	void (*remove)(struct mmc_host *);
+	void (*detect)(struct mmc_host *);
+};
+
+void mmc_attach_bus(struct mmc_host *host, const struct mmc_bus_ops *ops);
+void mmc_detach_bus(struct mmc_host *host);
+
+void __mmc_release_bus(struct mmc_host *host);
+
+static inline void mmc_bus_get(struct mmc_host *host)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&host->lock, flags);
+	host->bus_refs++;
+	spin_unlock_irqrestore(&host->lock, flags);
+}
+
+static inline void mmc_bus_put(struct mmc_host *host)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&host->lock, flags);
+	host->bus_refs--;
+	if ((host->bus_refs == 0) && host->bus_ops)
+		__mmc_release_bus(host);
+	spin_unlock_irqrestore(&host->lock, flags);
+}
+
 void mmc_set_chip_select(struct mmc_host *host, int mode);
+void mmc_set_clock(struct mmc_host *host, unsigned int hz);
+void mmc_set_bus_mode(struct mmc_host *host, unsigned int mode);
+void mmc_set_bus_width(struct mmc_host *host, unsigned int width);
+u32 mmc_select_voltage(struct mmc_host *host, u32 ocr);
+void mmc_set_timing(struct mmc_host *host, unsigned int timing);
+
+struct mmc_card *mmc_alloc_card(struct mmc_host *host);
 
 static inline void mmc_delay(unsigned int ms)
 {

drivers/mmc/core/mmc.c

···
+/*
+ *  linux/drivers/mmc/mmc.c
+ *
+ *  Copyright (C) 2003-2004 Russell King, All Rights Reserved.
+ *  Copyright (C) 2005-2007 Pierre Ossman, All Rights Reserved.
+ *  MMCv4 support Copyright (C) 2006 Philip Langdale, All Rights Reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/err.h>
+
+#include <linux/mmc/host.h>
+#include <linux/mmc/card.h>
+#include <linux/mmc/mmc.h>
+
+#include "core.h"
+#include "sysfs.h"
+#include "mmc_ops.h"
+
+static const unsigned int tran_exp[] = {
+	10000,		100000,		1000000,	10000000,
+	0,		0,		0,		0
+};
+
+static const unsigned char tran_mant[] = {
+	0,	10,	12,	13,	15,	20,	25,	30,
+	35,	40,	45,	50,	55,	60,	70,	80,
+};
+
+static const unsigned int tacc_exp[] = {
+	1,	10,	100,	1000,	10000,	100000,	1000000, 10000000,
+};
+
+static const unsigned int tacc_mant[] = {
+	0,	10,	12,	13,	15,	20,	25,	30,
+	35,	40,	45,	50,	55,	60,	70,	80,
+};
+
+#define UNSTUFF_BITS(resp,start,size)					\
+	({								\
+		const int __size = size;				\
+		const u32 __mask = (__size < 32 ? 1 << __size : 0) - 1;	\
+		const int __off = 3 - ((start) / 32);			\
+		const int __shft = (start) & 31;			\
+		u32 __res;						\
+									\
+		__res = resp[__off] >> __shft;				\
+		if (__size + __shft > 32)				\
+			__res |= resp[__off-1] << ((32 - __shft) % 32);	\
+		__res & __mask;						\
+	})
+
+/*
+ * Given the decoded CSD structure, decode the raw CID to our CID structure.
+ */
+static void mmc_decode_cid(struct mmc_card *card)
+{
+	u32 *resp = card->raw_cid;
+
+	/*
+	 * The selection of the format here is based upon published
+	 * specs from sandisk and from what people have reported.
+	 */
+	switch (card->csd.mmca_vsn) {
+	case 0: /* MMC v1.0 - v1.2 */
+	case 1: /* MMC v1.4 */
+		card->cid.manfid	= UNSTUFF_BITS(resp, 104, 24);
+		card->cid.prod_name[0]	= UNSTUFF_BITS(resp, 96, 8);
+		card->cid.prod_name[1]	= UNSTUFF_BITS(resp, 88, 8);
+		card->cid.prod_name[2]	= UNSTUFF_BITS(resp, 80, 8);
+		card->cid.prod_name[3]	= UNSTUFF_BITS(resp, 72, 8);
+		card->cid.prod_name[4]	= UNSTUFF_BITS(resp, 64, 8);
+		card->cid.prod_name[5]	= UNSTUFF_BITS(resp, 56, 8);
+		card->cid.prod_name[6]	= UNSTUFF_BITS(resp, 48, 8);
+		card->cid.hwrev		= UNSTUFF_BITS(resp, 44, 4);
+		card->cid.fwrev		= UNSTUFF_BITS(resp, 40, 4);
+		card->cid.serial	= UNSTUFF_BITS(resp, 16, 24);
+		card->cid.month		= UNSTUFF_BITS(resp, 12, 4);
+		card->cid.year		= UNSTUFF_BITS(resp, 8, 4) + 1997;
+		break;
+
+	case 2: /* MMC v2.0 - v2.2 */
+	case 3: /* MMC v3.1 - v3.3 */
+	case 4: /* MMC v4 */
+		card->cid.manfid	= UNSTUFF_BITS(resp, 120, 8);
+		card->cid.oemid		= UNSTUFF_BITS(resp, 104, 16);
+		card->cid.prod_name[0]	= UNSTUFF_BITS(resp, 96, 8);
+		card->cid.prod_name[1]	= UNSTUFF_BITS(resp, 88, 8);
+		card->cid.prod_name[2]	= UNSTUFF_BITS(resp, 80, 8);
+		card->cid.prod_name[3]	= UNSTUFF_BITS(resp, 72, 8);
+		card->cid.prod_name[4]	= UNSTUFF_BITS(resp, 64, 8);
+		card->cid.prod_name[5]	= UNSTUFF_BITS(resp, 56, 8);
+		card->cid.serial	= UNSTUFF_BITS(resp, 16, 32);
+		card->cid.month		= UNSTUFF_BITS(resp, 12, 4);
+		card->cid.year		= UNSTUFF_BITS(resp, 8, 4) + 1997;
+		break;
+
+	default:
+		printk("%s: card has unknown MMCA version %d\n",
+			mmc_hostname(card->host), card->csd.mmca_vsn);
+		mmc_card_set_bad(card);
+		break;
+	}
+}
+
+/*
+ * Given a 128-bit response, decode to our card CSD structure.
+ */
+static void mmc_decode_csd(struct mmc_card *card)
+{
+	struct mmc_csd *csd = &card->csd;
+	unsigned int e, m, csd_struct;
+	u32 *resp = card->raw_csd;
+
+	/*
+	 * We only understand CSD structure v1.1 and v1.2.
+	 * v1.2 has extra information in bits 15, 11 and 10.
+	 */
+	csd_struct = UNSTUFF_BITS(resp, 126, 2);
+	if (csd_struct != 1 && csd_struct != 2) {
+		printk("%s: unrecognised CSD structure version %d\n",
+			mmc_hostname(card->host), csd_struct);
+		mmc_card_set_bad(card);
+		return;
+	}
+
+	csd->mmca_vsn	 = UNSTUFF_BITS(resp, 122, 4);
+	m = UNSTUFF_BITS(resp, 115, 4);
+	e = UNSTUFF_BITS(resp, 112, 3);
+	csd->tacc_ns	 = (tacc_exp[e] * tacc_mant[m] + 9) / 10;
+	csd->tacc_clks	 = UNSTUFF_BITS(resp, 104, 8) * 100;
+
+	m = UNSTUFF_BITS(resp, 99, 4);
+	e = UNSTUFF_BITS(resp, 96, 3);
+	csd->max_dtr	  = tran_exp[e] * tran_mant[m];
+	csd->cmdclass	  = UNSTUFF_BITS(resp, 84, 12);
+
+	e = UNSTUFF_BITS(resp, 47, 3);
+	m = UNSTUFF_BITS(resp, 62, 12);
+	csd->capacity	  = (1 + m) << (e + 2);
+
+	csd->read_blkbits = UNSTUFF_BITS(resp, 80, 4);
+	csd->read_partial = UNSTUFF_BITS(resp, 79, 1);
+	csd->write_misalign = UNSTUFF_BITS(resp, 78, 1);
+	csd->read_misalign = UNSTUFF_BITS(resp, 77, 1);
+	csd->r2w_factor = UNSTUFF_BITS(resp, 26, 3);
+	csd->write_blkbits = UNSTUFF_BITS(resp, 22, 4);
+	csd->write_partial = UNSTUFF_BITS(resp, 21, 1);
+}
+
+/*
+ * Read and decode extended CSD. Switch to high-speed and wide bus
+ * if supported.
+ */
+static int mmc_process_ext_csd(struct mmc_card *card)
+{
+	int err;
+	u8 *ext_csd;
+
+	BUG_ON(!card);
+
+	err = MMC_ERR_FAILED;
+
+	if (card->csd.mmca_vsn < CSD_SPEC_VER_4)
+		return MMC_ERR_NONE;
+
+	/*
+	 * As the ext_csd is so large and mostly unused, we don't store the
+	 * raw block in mmc_card.
+	 */
+	ext_csd = kmalloc(512, GFP_KERNEL);
+	if (!ext_csd) {
+		printk(KERN_ERR "%s: could not allocate a buffer to "
+			"receive the ext_csd. mmc v4 cards will be "
+			"treated as v3.\n", mmc_hostname(card->host));
+		return MMC_ERR_FAILED;
+	}
+
+	err = mmc_send_ext_csd(card, ext_csd);
+	if (err != MMC_ERR_NONE) {
+		/*
+		 * High capacity cards should have this "magic" size
+		 * stored in their CSD.
+		 */
+		if (card->csd.capacity == (4096 * 512)) {
+			printk(KERN_ERR "%s: unable to read EXT_CSD "
+				"on a possible high capacity card. "
+				"Card will be ignored.\n",
+				mmc_hostname(card->host));
+		} else {
+			printk(KERN_WARNING "%s: unable to read "
+				"EXT_CSD, performance might "
+				"suffer.\n",
+				mmc_hostname(card->host));
+			err = MMC_ERR_NONE;
+		}
+		goto out;
+	}
+
+	card->ext_csd.sectors =
+		ext_csd[EXT_CSD_SEC_CNT + 0] << 0 |
+		ext_csd[EXT_CSD_SEC_CNT + 1] << 8 |
+		ext_csd[EXT_CSD_SEC_CNT + 2] << 16 |
+		ext_csd[EXT_CSD_SEC_CNT + 3] << 24;
+	if (card->ext_csd.sectors)
+		mmc_card_set_blockaddr(card);
+
+	switch (ext_csd[EXT_CSD_CARD_TYPE]) {
+	case EXT_CSD_CARD_TYPE_52 | EXT_CSD_CARD_TYPE_26:
+		card->ext_csd.hs_max_dtr = 52000000;
+		break;
+	case EXT_CSD_CARD_TYPE_26:
+		card->ext_csd.hs_max_dtr = 26000000;
+		break;
+	default:
+		/* MMC v4 spec says this cannot happen */
+		printk(KERN_WARNING "%s: card is mmc v4 but doesn't "
+			"support any high-speed modes.\n",
+			mmc_hostname(card->host));
+		goto out;
+	}
+
+	if (card->host->caps & MMC_CAP_MMC_HIGHSPEED) {
+		/* Activate highspeed support. */
+		err = mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
+			EXT_CSD_HS_TIMING, 1);
+		if (err != MMC_ERR_NONE) {
+			printk(KERN_WARNING "%s: failed to switch "
+				"card to mmc v4 high-speed mode.\n",
+			       mmc_hostname(card->host));
+			err = MMC_ERR_NONE;
+			goto out;
+		}
+
+		mmc_card_set_highspeed(card);
+
+		mmc_set_timing(card->host, MMC_TIMING_MMC_HS);
+	}
+
+	/* Check for host support for wide-bus modes. */
+	if (card->host->caps & MMC_CAP_4_BIT_DATA) {
+		/* Activate 4-bit support. */
+		err = mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
+			EXT_CSD_BUS_WIDTH, EXT_CSD_BUS_WIDTH_4);
+		if (err != MMC_ERR_NONE) {
+			printk(KERN_WARNING "%s: failed to switch "
+				"card to mmc v4 4-bit bus mode.\n",
+			       mmc_hostname(card->host));
+			err = MMC_ERR_NONE;
+			goto out;
+		}
+
+		mmc_set_bus_width(card->host, MMC_BUS_WIDTH_4);
+	}
+
+out:
+	kfree(ext_csd);
+
+	return err;
+}
+
+/*
+ * Host is being removed. Free up the current card.
+ */
+static void mmc_remove(struct mmc_host *host)
+{
+	BUG_ON(!host);
+	BUG_ON(!host->card);
+
+	mmc_remove_card(host->card);
+	host->card = NULL;
+}
+
+/*
+ * Card detection callback from host.
+ */
+static void mmc_detect(struct mmc_host *host)
+{
+	int err;
+
+	BUG_ON(!host);
+	BUG_ON(!host->card);
+
+	mmc_claim_host(host);
+
+	/*
+	 * Just check if our card has been removed.
+	 */
+	err = mmc_send_status(host->card, NULL);
+
+	mmc_release_host(host);
+
+	if (err != MMC_ERR_NONE) {
+		mmc_remove_card(host->card);
+		host->card = NULL;
+
+		mmc_claim_host(host);
+		mmc_detach_bus(host);
+		mmc_release_host(host);
+	}
+}
+
+static const struct mmc_bus_ops mmc_ops = {
+	.remove = mmc_remove,
+	.detect = mmc_detect,
+};
+
+/*
+ * Starting point for MMC card init.
+ */
+int mmc_attach_mmc(struct mmc_host *host, u32 ocr)
+{
+	struct mmc_card *card;
+	int err;
+	u32 cid[4];
+	unsigned int max_dtr;
+
+	BUG_ON(!host);
+	BUG_ON(!host->claimed);
+
+	mmc_attach_bus(host, &mmc_ops);
+
+	host->ocr = mmc_select_voltage(host, ocr);
+
+	/*
+	 * Can we support the voltage of the card?
+	 */
+	if (!host->ocr)
+		goto err;
+
+	/*
+	 * Since we're changing the OCR value, we seem to
+	 * need to tell some cards to go back to the idle
+	 * state.  We wait 1ms to give cards time to
+	 * respond.
+	 */
+	mmc_go_idle(host);
+
+	/* The extra bit indicates that we support high capacity */
+	mmc_send_op_cond(host, host->ocr | (1 << 30), NULL);
+
+	/*
+	 * Fetch CID from card.
+	 */
+	err = mmc_all_send_cid(host, cid);
+	if (err != MMC_ERR_NONE)
+		goto err;
+
+	/*
+	 * Allocate card structure.
+	 */
+	card = mmc_alloc_card(host);
+	if (IS_ERR(card))
+		goto err;
+
+	card->type = MMC_TYPE_MMC;
+	card->rca = 1;
+	memcpy(card->raw_cid, cid, sizeof(card->raw_cid));
+
+	/*
+	 * Set card RCA.
+	 */
+	err = mmc_set_relative_addr(card);
+	if (err != MMC_ERR_NONE)
+		goto free_card;
+
+	mmc_set_bus_mode(host, MMC_BUSMODE_PUSHPULL);
+
+	/*
+	 * Fetch CSD from card.
+	 */
+	err = mmc_send_csd(card, card->raw_csd);
+	if (err != MMC_ERR_NONE)
+		goto free_card;
+
+	mmc_decode_csd(card);
+	mmc_decode_cid(card);
+
+	/*
+	 * Fetch and process extened CSD.
+	 * This will switch into high-speed and wide bus modes,
+	 * as available.
+	 */
+	err = mmc_select_card(card);
+	if (err != MMC_ERR_NONE)
+		goto free_card;
+
+	err = mmc_process_ext_csd(card);
+	if (err != MMC_ERR_NONE)
+		goto free_card;
+
+	/*
+	 * Compute bus speed.
+	 */
+	max_dtr = (unsigned int)-1;
+
+	if (mmc_card_highspeed(card)) {
+		if (max_dtr > card->ext_csd.hs_max_dtr)
+			max_dtr = card->ext_csd.hs_max_dtr;
+	} else if (max_dtr > card->csd.max_dtr) {
+		max_dtr = card->csd.max_dtr;
+	}
+
+	mmc_set_clock(host, max_dtr);
+
+	host->card = card;
+
+	mmc_release_host(host);
+
+	err = mmc_register_card(card);
+	if (err)
+		goto reclaim_host;
+
+	return 0;
+
+reclaim_host:
+	mmc_claim_host(host);
+free_card:
+	mmc_remove_card(card);
+	host->card = NULL;
+err:
+	mmc_detach_bus(host);
+	mmc_release_host(host);
+
+	return 0;
+}
+

drivers/mmc/core/sd.c

···
+/*
+ *  linux/drivers/mmc/sd.c
+ *
+ *  Copyright (C) 2003-2004 Russell King, All Rights Reserved.
+ *  SD support Copyright (C) 2004 Ian Molton, All Rights Reserved.
+ *  Copyright (C) 2005-2007 Pierre Ossman, All Rights Reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/err.h>
+
+#include <linux/mmc/host.h>
+#include <linux/mmc/card.h>
+#include <linux/mmc/mmc.h>
+
+#include "core.h"
+#include "sysfs.h"
+#include "mmc_ops.h"
+#include "sd_ops.h"
+
+#include "core.h"
+
+static const unsigned int tran_exp[] = {
+	10000,		100000,		1000000,	10000000,
+	0,		0,		0,		0
+};
+
+static const unsigned char tran_mant[] = {
+	0,	10,	12,	13,	15,	20,	25,	30,
+	35,	40,	45,	50,	55,	60,	70,	80,
+};
+
+static const unsigned int tacc_exp[] = {
+	1,	10,	100,	1000,	10000,	100000,	1000000, 10000000,
+};
+
+static const unsigned int tacc_mant[] = {
+	0,	10,	12,	13,	15,	20,	25,	30,
+	35,	40,	45,	50,	55,	60,	70,	80,
+};
+
+#define UNSTUFF_BITS(resp,start,size)					\
+	({								\
+		const int __size = size;				\
+		const u32 __mask = (__size < 32 ? 1 << __size : 0) - 1;	\
+		const int __off = 3 - ((start) / 32);			\
+		const int __shft = (start) & 31;			\
+		u32 __res;						\
+									\
+		__res = resp[__off] >> __shft;				\
+		if (__size + __shft > 32)				\
+			__res |= resp[__off-1] << ((32 - __shft) % 32);	\
+		__res & __mask;						\
+	})
+
+/*
+ * Given the decoded CSD structure, decode the raw CID to our CID structure.
+ */
+static void mmc_decode_cid(struct mmc_card *card)
+{
+	u32 *resp = card->raw_cid;
+
+	memset(&card->cid, 0, sizeof(struct mmc_cid));
+
+	/*
+	 * SD doesn't currently have a version field so we will
+	 * have to assume we can parse this.
+	 */
+	card->cid.manfid		= UNSTUFF_BITS(resp, 120, 8);
+	card->cid.oemid			= UNSTUFF_BITS(resp, 104, 16);
+	card->cid.prod_name[0]		= UNSTUFF_BITS(resp, 96, 8);
+	card->cid.prod_name[1]		= UNSTUFF_BITS(resp, 88, 8);
+	card->cid.prod_name[2]		= UNSTUFF_BITS(resp, 80, 8);
+	card->cid.prod_name[3]		= UNSTUFF_BITS(resp, 72, 8);
+	card->cid.prod_name[4]		= UNSTUFF_BITS(resp, 64, 8);
+	card->cid.hwrev			= UNSTUFF_BITS(resp, 60, 4);
+	card->cid.fwrev			= UNSTUFF_BITS(resp, 56, 4);
+	card->cid.serial		= UNSTUFF_BITS(resp, 24, 32);
+	card->cid.year			= UNSTUFF_BITS(resp, 12, 8);
+	card->cid.month			= UNSTUFF_BITS(resp, 8, 4);
+
+	card->cid.year += 2000; /* SD cards year offset */
+}
+
+/*
+ * Given a 128-bit response, decode to our card CSD structure.
+ */
+static void mmc_decode_csd(struct mmc_card *card)
+{
+	struct mmc_csd *csd = &card->csd;
+	unsigned int e, m, csd_struct;
+	u32 *resp = card->raw_csd;
+
+	csd_struct = UNSTUFF_BITS(resp, 126, 2);
+
+	switch (csd_struct) {
+	case 0:
+		m = UNSTUFF_BITS(resp, 115, 4);
+		e = UNSTUFF_BITS(resp, 112, 3);
+		csd->tacc_ns	 = (tacc_exp[e] * tacc_mant[m] + 9) / 10;
+		csd->tacc_clks	 = UNSTUFF_BITS(resp, 104, 8) * 100;
+
+		m = UNSTUFF_BITS(resp, 99, 4);
+		e = UNSTUFF_BITS(resp, 96, 3);
+		csd->max_dtr	  = tran_exp[e] * tran_mant[m];
+		csd->cmdclass	  = UNSTUFF_BITS(resp, 84, 12);
+
+		e = UNSTUFF_BITS(resp, 47, 3);
+		m = UNSTUFF_BITS(resp, 62, 12);
+		csd->capacity	  = (1 + m) << (e + 2);
+
+		csd->read_blkbits = UNSTUFF_BITS(resp, 80, 4);
+		csd->read_partial = UNSTUFF_BITS(resp, 79, 1);
+		csd->write_misalign = UNSTUFF_BITS(resp, 78, 1);
+		csd->read_misalign = UNSTUFF_BITS(resp, 77, 1);
+		csd->r2w_factor = UNSTUFF_BITS(resp, 26, 3);
+		csd->write_blkbits = UNSTUFF_BITS(resp, 22, 4);
+		csd->write_partial = UNSTUFF_BITS(resp, 21, 1);
+		break;
+	case 1:
+		/*
+		 * This is a block-addressed SDHC card. Most
+		 * interesting fields are unused and have fixed
+		 * values. To avoid getting tripped by buggy cards,
+		 * we assume those fixed values ourselves.
+		 */
+		mmc_card_set_blockaddr(card);
+
+		csd->tacc_ns	 = 0; /* Unused */
+		csd->tacc_clks	 = 0; /* Unused */
+
+		m = UNSTUFF_BITS(resp, 99, 4);
+		e = UNSTUFF_BITS(resp, 96, 3);
+		csd->max_dtr	  = tran_exp[e] * tran_mant[m];
+		csd->cmdclass	  = UNSTUFF_BITS(resp, 84, 12);
+
+		m = UNSTUFF_BITS(resp, 48, 22);
+		csd->capacity     = (1 + m) << 10;
+
+		csd->read_blkbits = 9;
+		csd->read_partial = 0;
+		csd->write_misalign = 0;
+		csd->read_misalign = 0;
+		csd->r2w_factor = 4; /* Unused */
+		csd->write_blkbits = 9;
+		csd->write_partial = 0;
+		break;
+	default:
+		printk("%s: unrecognised CSD structure version %d\n",
+			mmc_hostname(card->host), csd_struct);
+		mmc_card_set_bad(card);
+		return;
+	}
+}
+
+/*
+ * Given a 64-bit response, decode to our card SCR structure.
+ */
+static void mmc_decode_scr(struct mmc_card *card)
+{
+	struct sd_scr *scr = &card->scr;
+	unsigned int scr_struct;
+	u32 resp[4];
+
+	BUG_ON(!mmc_card_sd(card));
+
+	resp[3] = card->raw_scr[1];
+	resp[2] = card->raw_scr[0];
+
+	scr_struct = UNSTUFF_BITS(resp, 60, 4);
+	if (scr_struct != 0) {
+		printk("%s: unrecognised SCR structure version %d\n",
+			mmc_hostname(card->host), scr_struct);
+		mmc_card_set_bad(card);
+		return;
+	}
+
+	scr->sda_vsn = UNSTUFF_BITS(resp, 56, 4);
+	scr->bus_widths = UNSTUFF_BITS(resp, 48, 4);
+}
+
+/*
+ * Test if the card supports high-speed mode and, if so, switch to it.
+ */
+static int mmc_switch_hs(struct mmc_card *card)
+{
+	int err;
+	u8 *status;
+
+	if (!(card->host->caps & MMC_CAP_SD_HIGHSPEED))
+		return MMC_ERR_NONE;
+
+	err = MMC_ERR_FAILED;
+
+	status = kmalloc(64, GFP_KERNEL);
+	if (!status) {
+		printk("%s: could not allocate a buffer for switch "
+		       "capabilities.\n",
+			mmc_hostname(card->host));
+		return err;
+	}
+
+	err = mmc_sd_switch(card, 0, 0, 1, status);
+	if (err != MMC_ERR_NONE) {
+		/*
+		 * Card not supporting high-speed will ignore the
+		 * command.
+		 */
+		if (err == MMC_ERR_TIMEOUT)
+			err = MMC_ERR_NONE;
+		goto out;
+	}
+
+	if (status[13] & 0x02)
+		card->sw_caps.hs_max_dtr = 50000000;
+
+	err = mmc_sd_switch(card, 1, 0, 1, status);
+	if (err != MMC_ERR_NONE)
+		goto out;
+
+	if ((status[16] & 0xF) != 1) {
+		printk(KERN_WARNING "%s: Problem switching card "
+			"into high-speed mode!\n",
+			mmc_hostname(card->host));
+	} else {
+		mmc_card_set_highspeed(card);
+		mmc_set_timing(card->host, MMC_TIMING_SD_HS);
+	}
+
+out:
+	kfree(status);
+
+	return err;
+}
+
+/*
+ * Host is being removed. Free up the current card.
+ */
+static void mmc_sd_remove(struct mmc_host *host)
+{
+	BUG_ON(!host);
+	BUG_ON(!host->card);
+
+	mmc_remove_card(host->card);
+	host->card = NULL;
+}
+
+/*
+ * Card detection callback from host.
+ */
+static void mmc_sd_detect(struct mmc_host *host)
+{
+	int err;
+
+	BUG_ON(!host);
+	BUG_ON(!host->card);
+
+	mmc_claim_host(host);
+
+	/*
+	 * Just check if our card has been removed.
+	 */
+	err = mmc_send_status(host->card, NULL);
+
+	mmc_release_host(host);
+
+	if (err != MMC_ERR_NONE) {
+		mmc_remove_card(host->card);
+		host->card = NULL;
+
+		mmc_claim_host(host);
+		mmc_detach_bus(host);
+		mmc_release_host(host);
+	}
+}
+
+static const struct mmc_bus_ops mmc_sd_ops = {
+	.remove = mmc_sd_remove,
+	.detect = mmc_sd_detect,
+};
+
+/*
+ * Starting point for SD card init.
+ */
+int mmc_attach_sd(struct mmc_host *host, u32 ocr)
+{
+	struct mmc_card *card;
+	int err;
+	u32 cid[4];
+	unsigned int max_dtr;
+
+	BUG_ON(!host);
+	BUG_ON(!host->claimed);
+
+	mmc_attach_bus(host, &mmc_sd_ops);
+
+	host->ocr = mmc_select_voltage(host, ocr);
+
+	/*
+	 * Can we support the voltage(s) of the card(s)?
+	 */
+	if (!host->ocr)
+		goto err;
+
+	/*
+	 * Since we're changing the OCR value, we seem to
+	 * need to tell some cards to go back to the idle
+	 * state.  We wait 1ms to give cards time to
+	 * respond.
+	 */
+	mmc_go_idle(host);
+
+	/*
+	 * If SD_SEND_IF_COND indicates an SD 2.0
+	 * compliant card and we should set bit 30
+	 * of the ocr to indicate that we can handle
+	 * block-addressed SDHC cards.
+	 */
+	err = mmc_send_if_cond(host, host->ocr);
+	if (err == MMC_ERR_NONE)
+		ocr = host->ocr | (1 << 30);
+
+	mmc_send_app_op_cond(host, ocr, NULL);
+
+	/*
+	 * Fetch CID from card.
+	 */
+	err = mmc_all_send_cid(host, cid);
+	if (err != MMC_ERR_NONE)
+		goto err;
+
+	/*
+	 * Allocate card structure.
+	 */
+	card = mmc_alloc_card(host);
+	if (IS_ERR(card))
+		goto err;
+
+	card->type = MMC_TYPE_SD;
+	memcpy(card->raw_cid, cid, sizeof(card->raw_cid));
+
+	/*
+	 * Set card RCA.
+	 */
+	err = mmc_send_relative_addr(host, &card->rca);
+	if (err != MMC_ERR_NONE)
+		goto free_card;
+
+	mmc_set_bus_mode(host, MMC_BUSMODE_PUSHPULL);
+
+	/*
+	 * Fetch CSD from card.
+	 */
+	err = mmc_send_csd(card, card->raw_csd);
+	if (err != MMC_ERR_NONE)
+		goto free_card;
+
+	mmc_decode_csd(card);
+	mmc_decode_cid(card);
+
+	/*
+	 * Fetch SCR from card.
+	 */
+	err = mmc_select_card(card);
+	if (err != MMC_ERR_NONE)
+		goto free_card;
+
+	err = mmc_app_send_scr(card, card->raw_scr);
+	if (err != MMC_ERR_NONE)
+		goto free_card;
+
+	mmc_decode_scr(card);
+
+	/*
+	 * Check if card can be switched into high-speed mode.
+	 */
+	err = mmc_switch_hs(card);
+	if (err != MMC_ERR_NONE)
+		goto free_card;
+
+	/*
+	 * Compute bus speed.
+	 */
+	max_dtr = (unsigned int)-1;
+
+	if (mmc_card_highspeed(card)) {
+		if (max_dtr > card->sw_caps.hs_max_dtr)
+			max_dtr = card->sw_caps.hs_max_dtr;
+	} else if (max_dtr > card->csd.max_dtr) {
+		max_dtr = card->csd.max_dtr;
+	}
+
+	mmc_set_clock(host, max_dtr);
+
+	/*
+	 * Switch to wider bus (if supported).
+	 */
+	if ((host->caps && MMC_CAP_4_BIT_DATA) &&
+		(card->scr.bus_widths & SD_SCR_BUS_WIDTH_4)) {
+		err = mmc_app_set_bus_width(card, MMC_BUS_WIDTH_4);
+		if (err != MMC_ERR_NONE)
+			goto free_card;
+
+		mmc_set_bus_width(host, MMC_BUS_WIDTH_4);
+	}
+
+	host->card = card;
+
+	mmc_release_host(host);
+
+	err = mmc_register_card(card);
+	if (err)
+		goto reclaim_host;
+
+	return 0;
+
+reclaim_host:
+	mmc_claim_host(host);
+free_card:
+	mmc_remove_card(card);
+	host->card = NULL;
+err:
+	mmc_detach_bus(host);
+	mmc_release_host(host);
+
+	return 0;
+}
+

include/linux/mmc/host.h

···
 	unsigned int		max_blk_count;	/* maximum number of blocks in one req */
 
 	/* private data */
+	spinlock_t		lock;		/* lock for claim and bus ops */
+
 	struct mmc_ios		ios;		/* current io bus settings */
 	u32			ocr;		/* the current OCR setting */
 
···
 	struct mmc_card		*card;		/* device attached to this host */
 
 	wait_queue_head_t	wq;
-	spinlock_t		lock;		/* claimed lock */
 	unsigned int		claimed:1;	/* host exclusively claimed */
 
 	struct delayed_work	detect;
 #ifdef CONFIG_MMC_DEBUG
 	unsigned int		removed:1;	/* host is being removed */
 #endif
+
+	const struct mmc_bus_ops *bus_ops;	/* current bus driver */
+	unsigned int		bus_refs;	/* reference counter */
+	unsigned int		bus_dead:1;	/* bus has been released */
 
 	unsigned long		private[0] ____cacheline_aligned;
 };