mmc: deprecate mmc bus topology

The classic MMC bus was defined as multi card bus
system, which is reflected in the design in the MMC
layer.

When SD showed up, the bus topology was abandoned
and a star topology (one card per host) was mandated.
MMC version 4 has followed this, officially deprecating
the bus topology.

As we do not have any known users of the bus
topology we can remove support for it. This will
simplify the code and rectify some incorrect
assumptions in the newer additions.

Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>

2 files changed, 398 insertions, 536 deletions

diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c
index 8eba037..8a84e4d 100644
--- a/drivers/mmc/card/block.c
+++ b/drivers/mmc/card/block.c
@@ -226,8 +226,7 @@ static int mmc_blk_issue_rq(struct mmc_queue *mq, struct request *req)
 	struct mmc_blk_request brq;
 	int ret = 1, sg_pos, data_size;
 
-	if (mmc_card_claim_host(card))
-		goto flush_queue;
+	mmc_claim_host(card->host);
 
 	do {
 		struct mmc_command cmd;
@@ -357,7 +356,7 @@ static int mmc_blk_issue_rq(struct mmc_queue *mq, struct request *req)
 		spin_unlock_irq(&md->lock);
 	} while (ret);
 
-	mmc_card_release_host(card);
+	mmc_release_host(card->host);
 
 	return 1;
 
@@ -393,9 +392,7 @@ static int mmc_blk_issue_rq(struct mmc_queue *mq, struct request *req)
 		spin_unlock_irq(&md->lock);
 	}
 
-flush_queue:
-
-	mmc_card_release_host(card);
+	mmc_release_host(card->host);
 
 	spin_lock_irq(&md->lock);
 	while (ret) {
@@ -526,12 +523,12 @@ mmc_blk_set_blksize(struct mmc_blk_data *md, struct mmc_card *card)
 	if (mmc_card_blockaddr(card))
 		return 0;
 
-	mmc_card_claim_host(card);
+	mmc_claim_host(card->host);
 	cmd.opcode = MMC_SET_BLOCKLEN;
 	cmd.arg = 1 << md->block_bits;
 	cmd.flags = MMC_RSP_R1 | MMC_CMD_AC;
 	err = mmc_wait_for_cmd(card->host, &cmd, 5);
-	mmc_card_release_host(card);
+	mmc_release_host(card->host);
 
 	if (err) {
 		printk(KERN_ERR "%s: unable to set block size to %d: %d\n",
diff --git a/drivers/mmc/mmc.c b/drivers/mmc/mmc.c
index 94c0472..3f50b88 100644
--- a/drivers/mmc/mmc.c
+++ b/drivers/mmc/mmc.c
@@ -3,7 +3,7 @@
  *
  *  Copyright (C) 2003-2004 Russell King, All Rights Reserved.
  *  SD support Copyright (C) 2004 Ian Molton, All Rights Reserved.
- *  SD support Copyright (C) 2005 Pierre Ossman, 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
@@ -316,8 +316,6 @@ void mmc_set_data_timeout(struct mmc_data *data, const struct mmc_card *card,
 }
 EXPORT_SYMBOL(mmc_set_data_timeout);
 
-static int mmc_select_card(struct mmc_host *host, struct mmc_card *card);
-
 /**
  *	__mmc_claim_host - exclusively claim a host
  *	@host: mmc host to claim
@@ -329,11 +327,10 @@ static int mmc_select_card(struct mmc_host *host, struct mmc_card *card);
  *
  *	Note: you should use mmc_card_claim_host or mmc_claim_host.
  */
-int __mmc_claim_host(struct mmc_host *host, struct mmc_card *card)
+void mmc_claim_host(struct mmc_host *host)
 {
 	DECLARE_WAITQUEUE(wait, current);
 	unsigned long flags;
-	int err = 0;
 
 	add_wait_queue(&host->wq, &wait);
 	spin_lock_irqsave(&host->lock, flags);
@@ -349,17 +346,9 @@ int __mmc_claim_host(struct mmc_host *host, struct mmc_card *card)
 	host->claimed = 1;
 	spin_unlock_irqrestore(&host->lock, flags);
 	remove_wait_queue(&host->wq, &wait);
-
-	if (card != (void *)-1) {
-		err = mmc_select_card(host, card);
-		if (err != MMC_ERR_NONE)
-			return err;
-	}
-
-	return err;
 }
 
-EXPORT_SYMBOL(__mmc_claim_host);
+EXPORT_SYMBOL(mmc_claim_host);
 
 /**
  *	mmc_release_host - release a host
@@ -396,23 +385,18 @@ static inline void mmc_set_ios(struct mmc_host *host)
 	host->ops->set_ios(host, ios);
 }
 
-static int mmc_select_card(struct mmc_host *host, struct mmc_card *card)
+static int mmc_select_card(struct mmc_card *card)
 {
 	int err;
 	struct mmc_command cmd;
 
-	BUG_ON(!host->claimed);
-
-	if (host->card_selected == card)
-		return MMC_ERR_NONE;
-
-	host->card_selected = card;
+	BUG_ON(!card->host->claimed);
 
 	cmd.opcode = MMC_SELECT_CARD;
 	cmd.arg = card->rca << 16;
 	cmd.flags = MMC_RSP_R1 | MMC_CMD_AC;
 
-	err = mmc_wait_for_cmd(host, &cmd, CMD_RETRIES);
+	err = mmc_wait_for_cmd(card->host, &cmd, CMD_RETRIES);
 	if (err != MMC_ERR_NONE)
 		return err;
 
@@ -426,49 +410,24 @@ static int mmc_select_card(struct mmc_host *host, struct mmc_card *card)
 	 * wider version.
 	 */
 	if (mmc_card_sd(card) &&
-		(card->scr.bus_widths & SD_SCR_BUS_WIDTH_4)) {
+		(card->scr.bus_widths & SD_SCR_BUS_WIDTH_4) &&
+		(card->host->caps & MMC_CAP_4_BIT_DATA)) {
 
-		/*
-		* Default bus width is 1 bit.
-		*/
-		host->ios.bus_width = MMC_BUS_WIDTH_1;
-
-		if (host->caps & MMC_CAP_4_BIT_DATA) {
-			struct mmc_command cmd;
-			cmd.opcode = SD_APP_SET_BUS_WIDTH;
-			cmd.arg = SD_BUS_WIDTH_4;
-			cmd.flags = MMC_RSP_R1 | MMC_CMD_AC;
-
-			err = mmc_wait_for_app_cmd(host, card->rca, &cmd,
-				CMD_RETRIES);
-			if (err != MMC_ERR_NONE)
-				return err;
-
-			host->ios.bus_width = MMC_BUS_WIDTH_4;
-		}
-	}
-
-	mmc_set_ios(host);
-
-	return MMC_ERR_NONE;
-}
-
-/*
- * Ensure that no card is selected.
- */
-static void mmc_deselect_cards(struct mmc_host *host)
-{
-	struct mmc_command cmd;
-
-	if (host->card_selected) {
-		host->card_selected = NULL;
+		struct mmc_command cmd;
+		cmd.opcode = SD_APP_SET_BUS_WIDTH;
+		cmd.arg = SD_BUS_WIDTH_4;
+		cmd.flags = MMC_RSP_R1 | MMC_CMD_AC;
 
-		cmd.opcode = MMC_SELECT_CARD;
-		cmd.arg = 0;
-		cmd.flags = MMC_RSP_NONE | MMC_CMD_AC;
+		err = mmc_wait_for_app_cmd(card->host, card->rca,
+			&cmd, CMD_RETRIES);
+		if (err != MMC_ERR_NONE)
+			return err;
 
-		mmc_wait_for_cmd(host, &cmd, 0);
+		card->host->ios.bus_width = MMC_BUS_WIDTH_4;
+		mmc_set_ios(card->host);
 	}
+
+	return MMC_ERR_NONE;
 }
 
 
@@ -732,27 +691,12 @@ static void mmc_decode_scr(struct mmc_card *card)
 }
 
 /*
- * Locate a MMC card on this MMC host given a raw CID.
- */
-static struct mmc_card *mmc_find_card(struct mmc_host *host, u32 *raw_cid)
-{
-	struct mmc_card *card;
-
-	list_for_each_entry(card, &host->cards, node) {
-		if (memcmp(card->raw_cid, raw_cid, sizeof(card->raw_cid)) == 0)
-			return card;
-	}
-	return NULL;
-}
-
-/*
- * Allocate a new MMC card, and assign a unique RCA.
+ * Allocate a new MMC card
  */
 static struct mmc_card *
-mmc_alloc_card(struct mmc_host *host, u32 *raw_cid, unsigned int *frca)
+mmc_alloc_card(struct mmc_host *host, u32 *raw_cid)
 {
-	struct mmc_card *card, *c;
-	unsigned int rca = *frca;
+	struct mmc_card *card;
 
 	card = kmalloc(sizeof(struct mmc_card), GFP_KERNEL);
 	if (!card)
@@ -761,17 +705,6 @@ mmc_alloc_card(struct mmc_host *host, u32 *raw_cid, unsigned int *frca)
 	mmc_init_card(card, host);
 	memcpy(card->raw_cid, raw_cid, sizeof(card->raw_cid));
 
- again:
-	list_for_each_entry(c, &host->cards, node)
-		if (c->rca == rca) {
-			rca++;
-			goto again;
-		}
-
-	card->rca = rca;
-
-	*frca = rca;
-
 	return card;
 }
 
@@ -937,128 +870,128 @@ static int mmc_send_if_cond(struct mmc_host *host, u32 ocr, int *rsd2)
 }
 
 /*
- * Discover cards by requesting their CID.  If this command
- * times out, it is not an error; there are no further cards
- * to be discovered.  Add new cards to the list.
+ * Discover the card by requesting its CID.
  *
- * Create a mmc_card entry for each discovered card, assigning
+ * Create a mmc_card entry for the discovered card, assigning
  * it an RCA, and save the raw CID for decoding later.
  */
-static void mmc_discover_cards(struct mmc_host *host)
+static void mmc_discover_card(struct mmc_host *host)
 {
-	struct mmc_card *card;
-	unsigned int first_rca = 1, err;
+	unsigned int err;
 
-	while (1) {
-		struct mmc_command cmd;
+	struct mmc_command cmd;
 
-		cmd.opcode = MMC_ALL_SEND_CID;
+	BUG_ON(host->card);
+
+	cmd.opcode = MMC_ALL_SEND_CID;
+	cmd.arg = 0;
+	cmd.flags = MMC_RSP_R2 | MMC_CMD_BCR;
+
+	err = mmc_wait_for_cmd(host, &cmd, CMD_RETRIES);
+	if (err == MMC_ERR_TIMEOUT) {
+		err = MMC_ERR_NONE;
+		return;
+	}
+	if (err != MMC_ERR_NONE) {
+		printk(KERN_ERR "%s: error requesting CID: %d\n",
+			mmc_hostname(host), err);
+		return;
+	}
+
+	host->card = mmc_alloc_card(host, cmd.resp);
+	if (IS_ERR(host->card)) {
+		err = PTR_ERR(host->card);
+		host->card = NULL;
+		return;
+	}
+
+	if (host->mode == MMC_MODE_SD) {
+		host->card->type = MMC_TYPE_SD;
+
+		cmd.opcode = SD_SEND_RELATIVE_ADDR;
 		cmd.arg = 0;
-		cmd.flags = MMC_RSP_R2 | MMC_CMD_BCR;
+		cmd.flags = MMC_RSP_R6 | MMC_CMD_BCR;
 
 		err = mmc_wait_for_cmd(host, &cmd, CMD_RETRIES);
-		if (err == MMC_ERR_TIMEOUT) {
-			err = MMC_ERR_NONE;
-			break;
-		}
-		if (err != MMC_ERR_NONE) {
-			printk(KERN_ERR "%s: error requesting CID: %d\n",
-				mmc_hostname(host), err);
-			break;
-		}
-
-		card = mmc_find_card(host, cmd.resp);
-		if (!card) {
-			card = mmc_alloc_card(host, cmd.resp, &first_rca);
-			if (IS_ERR(card)) {
-				err = PTR_ERR(card);
-				break;
+		if (err != MMC_ERR_NONE)
+			mmc_card_set_dead(host->card);
+		else {
+			host->card->rca = cmd.resp[0] >> 16;
+
+			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);
 			}
-			list_add(&card->node, &host->cards);
 		}
+	} else {
+		host->card->type = MMC_TYPE_MMC;
+		host->card->rca = 1;
 
-		card->state &= ~MMC_STATE_DEAD;
-
-		if (host->mode == MMC_MODE_SD) {
-			card->type = MMC_TYPE_SD;
-
-			cmd.opcode = SD_SEND_RELATIVE_ADDR;
-			cmd.arg = 0;
-			cmd.flags = MMC_RSP_R6 | MMC_CMD_BCR;
-
-			err = mmc_wait_for_cmd(host, &cmd, CMD_RETRIES);
-			if (err != MMC_ERR_NONE)
-				mmc_card_set_dead(card);
-			else {
-				card->rca = cmd.resp[0] >> 16;
-
-				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(card);
-				}
-			}
-		} else {
-			card->type = MMC_TYPE_MMC;
-			cmd.opcode = MMC_SET_RELATIVE_ADDR;
-			cmd.arg = card->rca << 16;
-			cmd.flags = MMC_RSP_R1 | MMC_CMD_AC;
-
-			err = mmc_wait_for_cmd(host, &cmd, CMD_RETRIES);
-			if (err != MMC_ERR_NONE)
-				mmc_card_set_dead(card);
-		}
+		cmd.opcode = MMC_SET_RELATIVE_ADDR;
+		cmd.arg = host->card->rca << 16;
+		cmd.flags = MMC_RSP_R1 | MMC_CMD_AC;
+
+		err = mmc_wait_for_cmd(host, &cmd, CMD_RETRIES);
+		if (err != MMC_ERR_NONE)
+			mmc_card_set_dead(host->card);
 	}
 }
 
-static void mmc_read_csds(struct mmc_host *host)
+static void mmc_read_csd(struct mmc_host *host)
 {
-	struct mmc_card *card;
-
-	list_for_each_entry(card, &host->cards, node) {
-		struct mmc_command cmd;
-		int err;
+	struct mmc_command cmd;
+	int err;
 
-		if (card->state & (MMC_STATE_DEAD|MMC_STATE_PRESENT))
-			continue;
+	if (!host->card)
+		return;
+	if (mmc_card_dead(host->card))
+		return;
 
-		cmd.opcode = MMC_SEND_CSD;
-		cmd.arg = card->rca << 16;
-		cmd.flags = MMC_RSP_R2 | MMC_CMD_AC;
+	cmd.opcode = MMC_SEND_CSD;
+	cmd.arg = host->card->rca << 16;
+	cmd.flags = MMC_RSP_R2 | MMC_CMD_AC;
 
-		err = mmc_wait_for_cmd(host, &cmd, CMD_RETRIES);
-		if (err != MMC_ERR_NONE) {
-			mmc_card_set_dead(card);
-			continue;
-		}
+	err = mmc_wait_for_cmd(host, &cmd, CMD_RETRIES);
+	if (err != MMC_ERR_NONE) {
+		mmc_card_set_dead(host->card);
+		return;
+	}
 
-		memcpy(card->raw_csd, cmd.resp, sizeof(card->raw_csd));
+	memcpy(host->card->raw_csd, cmd.resp, sizeof(host->card->raw_csd));
 
-		mmc_decode_csd(card);
-		mmc_decode_cid(card);
-	}
+	mmc_decode_csd(host->card);
+	mmc_decode_cid(host->card);
 }
 
-static void mmc_process_ext_csds(struct mmc_host *host)
+static void mmc_process_ext_csd(struct mmc_host *host)
 {
 	int err;
-	struct mmc_card *card;
 
 	struct mmc_request mrq;
 	struct mmc_command cmd;
 	struct mmc_data data;
 
+	u8 *ext_csd;
 	struct scatterlist sg;
 
+	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.
 	 */
-	u8 *ext_csd;
 	ext_csd = kmalloc(512, GFP_KERNEL);
 	if (!ext_csd) {
 		printk("%s: could not allocate a buffer to receive the ext_csd."
@@ -1067,211 +1000,184 @@ static void mmc_process_ext_csds(struct mmc_host *host)
 		return;
 	}
 
-	list_for_each_entry(card, &host->cards, node) {
-		if (card->state & (MMC_STATE_DEAD|MMC_STATE_PRESENT))
-			continue;
-		if (mmc_card_sd(card))
-			continue;
-		if (card->csd.mmca_vsn < CSD_SPEC_VER_4)
-			continue;
-
-		err = mmc_select_card(host, card);
-		if (err != MMC_ERR_NONE) {
-			mmc_card_set_dead(card);
-			continue;
-		}
-
-		memset(&cmd, 0, sizeof(struct mmc_command));
+	memset(&cmd, 0, sizeof(struct mmc_command));
 
-		cmd.opcode = MMC_SEND_EXT_CSD;
-		cmd.arg = 0;
-		cmd.flags = MMC_RSP_R1 | MMC_CMD_ADTC;
+	cmd.opcode = MMC_SEND_EXT_CSD;
+	cmd.arg = 0;
+	cmd.flags = MMC_RSP_R1 | MMC_CMD_ADTC;
 
-		memset(&data, 0, sizeof(struct mmc_data));
+	memset(&data, 0, sizeof(struct mmc_data));
 
-		mmc_set_data_timeout(&data, card, 0);
+	mmc_set_data_timeout(&data, host->card, 0);
 
-		data.blksz = 512;
-		data.blocks = 1;
-		data.flags = MMC_DATA_READ;
-		data.sg = &sg;
-		data.sg_len = 1;
+	data.blksz = 512;
+	data.blocks = 1;
+	data.flags = MMC_DATA_READ;
+	data.sg = &sg;
+	data.sg_len = 1;
 
-		memset(&mrq, 0, sizeof(struct mmc_request));
+	memset(&mrq, 0, sizeof(struct mmc_request));
 
-		mrq.cmd = &cmd;
-		mrq.data = &data;
+	mrq.cmd = &cmd;
+	mrq.data = &data;
 
-		sg_init_one(&sg, ext_csd, 512);
+	sg_init_one(&sg, ext_csd, 512);
 
-		mmc_wait_for_req(host, &mrq);
+	mmc_wait_for_req(host, &mrq);
 
-		if (cmd.error != MMC_ERR_NONE || data.error != MMC_ERR_NONE) {
-			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));
-				mmc_card_set_dead(card);
-			} else {
-				printk(KERN_WARNING "%s: unable to read "
-					"EXT_CSD, performance might "
-					"suffer.\n",
-					mmc_hostname(card->host));
-			}
-			continue;
+	if (cmd.error != MMC_ERR_NONE || data.error != 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;
+	}
 
-		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);
+	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;
+	}
 
-		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("%s: card is mmc v4 but doesn't support "
-			       "any high-speed modes.\n",
-				mmc_hostname(card->host));
-			continue;
-		}
+	if (host->caps & MMC_CAP_MMC_HIGHSPEED) {
+		/* Activate highspeed support. */
+		cmd.opcode = MMC_SWITCH;
+		cmd.arg = (MMC_SWITCH_MODE_WRITE_BYTE << 24) |
+			  (EXT_CSD_HS_TIMING << 16) |
+			  (1 << 8) |
+			  EXT_CSD_CMD_SET_NORMAL;
+		cmd.flags = MMC_RSP_R1B | MMC_CMD_AC;
 
-		if (host->caps & MMC_CAP_MMC_HIGHSPEED) {
-			/* Activate highspeed support. */
-			cmd.opcode = MMC_SWITCH;
-			cmd.arg = (MMC_SWITCH_MODE_WRITE_BYTE << 24) |
-				  (EXT_CSD_HS_TIMING << 16) |
-				  (1 << 8) |
-				  EXT_CSD_CMD_SET_NORMAL;
-			cmd.flags = MMC_RSP_R1B | MMC_CMD_AC;
-
-			err = mmc_wait_for_cmd(host, &cmd, CMD_RETRIES);
-			if (err != MMC_ERR_NONE) {
-				printk("%s: failed to switch card to mmc v4 "
-				       "high-speed mode.\n",
-				       mmc_hostname(card->host));
-				continue;
-			}
+		err = mmc_wait_for_cmd(host, &cmd, CMD_RETRIES);
+		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(card);
+		mmc_card_set_highspeed(host->card);
 
-			host->ios.timing = MMC_TIMING_MMC_HS;
-			mmc_set_ios(host);
-		}
+		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. */
-			cmd.opcode = MMC_SWITCH;
-			cmd.arg = (MMC_SWITCH_MODE_WRITE_BYTE << 24) |
-				  (EXT_CSD_BUS_WIDTH << 16) |
-				  (EXT_CSD_BUS_WIDTH_4 << 8) |
-				  EXT_CSD_CMD_SET_NORMAL;
-			cmd.flags = MMC_RSP_R1B | MMC_CMD_AC;
-
-			err = mmc_wait_for_cmd(host, &cmd, CMD_RETRIES);
-			if (err != MMC_ERR_NONE) {
-				printk("%s: failed to switch card to "
-				       "mmc v4 4-bit bus mode.\n",
-				       mmc_hostname(card->host));
-				continue;
-			}
+	/* Check for host support for wide-bus modes. */
+	if (host->caps & MMC_CAP_4_BIT_DATA) {
+		/* Activate 4-bit support. */
+		cmd.opcode = MMC_SWITCH;
+		cmd.arg = (MMC_SWITCH_MODE_WRITE_BYTE << 24) |
+			  (EXT_CSD_BUS_WIDTH << 16) |
+			  (EXT_CSD_BUS_WIDTH_4 << 8) |
+			  EXT_CSD_CMD_SET_NORMAL;
+		cmd.flags = MMC_RSP_R1B | MMC_CMD_AC;
 
-			host->ios.bus_width = MMC_BUS_WIDTH_4;
-			mmc_set_ios(host);
+		err = mmc_wait_for_cmd(host, &cmd, CMD_RETRIES);
+		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);
-
-	mmc_deselect_cards(host);
 }
 
-static void mmc_read_scrs(struct mmc_host *host)
+static void mmc_read_scr(struct mmc_host *host)
 {
 	int err;
-	struct mmc_card *card;
 	struct mmc_request mrq;
 	struct mmc_command cmd;
 	struct mmc_data data;
 	struct scatterlist sg;
 
-	list_for_each_entry(card, &host->cards, node) {
-		if (card->state & (MMC_STATE_DEAD|MMC_STATE_PRESENT))
-			continue;
-		if (!mmc_card_sd(card))
-			continue;
-
-		err = mmc_select_card(host, card);
-		if (err != MMC_ERR_NONE) {
-			mmc_card_set_dead(card);
-			continue;
-		}
-
-		memset(&cmd, 0, sizeof(struct mmc_command));
-
-		cmd.opcode = MMC_APP_CMD;
-		cmd.arg = card->rca << 16;
-		cmd.flags = MMC_RSP_R1 | MMC_CMD_AC;
+	if (!host->card)
+		return;
+	if (mmc_card_dead(host->card))
+		return;
+	if (!mmc_card_sd(host->card))
+		return;
 
-		err = mmc_wait_for_cmd(host, &cmd, 0);
-		if ((err != MMC_ERR_NONE) || !(cmd.resp[0] & R1_APP_CMD)) {
-			mmc_card_set_dead(card);
-			continue;
-		}
+	memset(&cmd, 0, sizeof(struct mmc_command));
 
-		memset(&cmd, 0, sizeof(struct mmc_command));
+	cmd.opcode = MMC_APP_CMD;
+	cmd.arg = host->card->rca << 16;
+	cmd.flags = MMC_RSP_R1 | MMC_CMD_AC;
 
-		cmd.opcode = SD_APP_SEND_SCR;
-		cmd.arg = 0;
-		cmd.flags = MMC_RSP_R1 | MMC_CMD_ADTC;
+	err = mmc_wait_for_cmd(host, &cmd, 0);
+	if ((err != MMC_ERR_NONE) || !(cmd.resp[0] & R1_APP_CMD)) {
+		mmc_card_set_dead(host->card);
+		return;
+	}
 
-		memset(&data, 0, sizeof(struct mmc_data));
+	memset(&cmd, 0, sizeof(struct mmc_command));
 
-		mmc_set_data_timeout(&data, card, 0);
+	cmd.opcode = SD_APP_SEND_SCR;
+	cmd.arg = 0;
+	cmd.flags = MMC_RSP_R1 | MMC_CMD_ADTC;
 
-		data.blksz = 1 << 3;
-		data.blocks = 1;
-		data.flags = MMC_DATA_READ;
-		data.sg = &sg;
-		data.sg_len = 1;
+	memset(&data, 0, sizeof(struct mmc_data));
 
-		memset(&mrq, 0, sizeof(struct mmc_request));
+	mmc_set_data_timeout(&data, host->card, 0);
 
-		mrq.cmd = &cmd;
-		mrq.data = &data;
+	data.blksz = 1 << 3;
+	data.blocks = 1;
+	data.flags = MMC_DATA_READ;
+	data.sg = &sg;
+	data.sg_len = 1;
 
-		sg_init_one(&sg, (u8*)card->raw_scr, 8);
+	memset(&mrq, 0, sizeof(struct mmc_request));
 
-		mmc_wait_for_req(host, &mrq);
+	mrq.cmd = &cmd;
+	mrq.data = &data;
 
-		if (cmd.error != MMC_ERR_NONE || data.error != MMC_ERR_NONE) {
-			mmc_card_set_dead(card);
-			continue;
-		}
+	sg_init_one(&sg, (u8*)host->card->raw_scr, 8);
 
-		card->raw_scr[0] = ntohl(card->raw_scr[0]);
-		card->raw_scr[1] = ntohl(card->raw_scr[1]);
+	mmc_wait_for_req(host, &mrq);
 
-		mmc_decode_scr(card);
+	if (cmd.error != MMC_ERR_NONE || data.error != MMC_ERR_NONE) {
+		mmc_card_set_dead(host->card);
+		return;
 	}
 
-	mmc_deselect_cards(host);
+	host->card->raw_scr[0] = ntohl(host->card->raw_scr[0]);
+	host->card->raw_scr[1] = ntohl(host->card->raw_scr[1]);
+
+	mmc_decode_scr(host->card);
 }
 
 static void mmc_read_switch_caps(struct mmc_host *host)
 {
-	int err;
-	struct mmc_card *card;
 	struct mmc_request mrq;
 	struct mmc_command cmd;
 	struct mmc_data data;
@@ -1281,6 +1187,15 @@ static void mmc_read_switch_caps(struct mmc_host *host)
 	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 "
@@ -1289,116 +1204,98 @@ static void mmc_read_switch_caps(struct mmc_host *host)
 		return;
 	}
 
-	list_for_each_entry(card, &host->cards, node) {
-		if (card->state & (MMC_STATE_DEAD|MMC_STATE_PRESENT))
-			continue;
-		if (!mmc_card_sd(card))
-			continue;
-		if (card->scr.sda_vsn < SCR_SPEC_VER_1)
-			continue;
-
-		err = mmc_select_card(host, card);
-		if (err != MMC_ERR_NONE) {
-			mmc_card_set_dead(card);
-			continue;
-		}
-
-		memset(&cmd, 0, sizeof(struct mmc_command));
+	memset(&cmd, 0, sizeof(struct mmc_command));
 
-		cmd.opcode = SD_SWITCH;
-		cmd.arg = 0x00FFFFF1;
-		cmd.flags = MMC_RSP_R1 | MMC_CMD_ADTC;
+	cmd.opcode = SD_SWITCH;
+	cmd.arg = 0x00FFFFF1;
+	cmd.flags = MMC_RSP_R1 | MMC_CMD_ADTC;
 
-		memset(&data, 0, sizeof(struct mmc_data));
+	memset(&data, 0, sizeof(struct mmc_data));
 
-		mmc_set_data_timeout(&data, card, 0);
+	mmc_set_data_timeout(&data, host->card, 0);
 
-		data.blksz = 64;
-		data.blocks = 1;
-		data.flags = MMC_DATA_READ;
-		data.sg = &sg;
-		data.sg_len = 1;
+	data.blksz = 64;
+	data.blocks = 1;
+	data.flags = MMC_DATA_READ;
+	data.sg = &sg;
+	data.sg_len = 1;
 
-		memset(&mrq, 0, sizeof(struct mmc_request));
+	memset(&mrq, 0, sizeof(struct mmc_request));
 
-		mrq.cmd = &cmd;
-		mrq.data = &data;
+	mrq.cmd = &cmd;
+	mrq.data = &data;
 
-		sg_init_one(&sg, status, 64);
+	sg_init_one(&sg, status, 64);
 
-		mmc_wait_for_req(host, &mrq);
+	mmc_wait_for_req(host, &mrq);
 
-		if (cmd.error != MMC_ERR_NONE || data.error != MMC_ERR_NONE) {
-			printk("%s: unable to read switch capabilities, "
-				"performance might suffer.\n",
-				mmc_hostname(card->host));
-			continue;
-		}
+	if (cmd.error != MMC_ERR_NONE || data.error != MMC_ERR_NONE) {
+		printk("%s: unable to read switch capabilities, "
+			"performance might suffer.\n",
+			mmc_hostname(host));
+		goto out;
+	}
 
-		if (status[13] & 0x02)
-			card->sw_caps.hs_max_dtr = 50000000;
+	if (status[13] & 0x02)
+		host->card->sw_caps.hs_max_dtr = 50000000;
 
-		memset(&cmd, 0, sizeof(struct mmc_command));
+	memset(&cmd, 0, sizeof(struct mmc_command));
 
-		cmd.opcode = SD_SWITCH;
-		cmd.arg = 0x80FFFFF1;
-		cmd.flags = MMC_RSP_R1 | MMC_CMD_ADTC;
+	cmd.opcode = SD_SWITCH;
+	cmd.arg = 0x80FFFFF1;
+	cmd.flags = MMC_RSP_R1 | MMC_CMD_ADTC;
 
-		memset(&data, 0, sizeof(struct mmc_data));
+	memset(&data, 0, sizeof(struct mmc_data));
 
-		mmc_set_data_timeout(&data, card, 0);
+	mmc_set_data_timeout(&data, host->card, 0);
 
-		data.blksz = 64;
-		data.blocks = 1;
-		data.flags = MMC_DATA_READ;
-		data.sg = &sg;
-		data.sg_len = 1;
+	data.blksz = 64;
+	data.blocks = 1;
+	data.flags = MMC_DATA_READ;
+	data.sg = &sg;
+	data.sg_len = 1;
 
-		memset(&mrq, 0, sizeof(struct mmc_request));
+	memset(&mrq, 0, sizeof(struct mmc_request));
 
-		mrq.cmd = &cmd;
-		mrq.data = &data;
+	mrq.cmd = &cmd;
+	mrq.data = &data;
 
-		sg_init_one(&sg, status, 64);
+	sg_init_one(&sg, status, 64);
 
-		mmc_wait_for_req(host, &mrq);
+	mmc_wait_for_req(host, &mrq);
 
-		if (cmd.error != MMC_ERR_NONE || data.error != MMC_ERR_NONE ||
-			(status[16] & 0xF) != 1) {
-			printk(KERN_WARNING "%s: Problem switching card "
-				"into high-speed mode!\n",
-				mmc_hostname(host));
-			continue;
-		}
+	if (cmd.error != MMC_ERR_NONE || data.error != 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(card);
+	mmc_card_set_highspeed(host->card);
 
-		host->ios.timing = MMC_TIMING_SD_HS;
-		mmc_set_ios(host);
-	}
+	host->ios.timing = MMC_TIMING_SD_HS;
+	mmc_set_ios(host);
 
+out:
 	kfree(status);
-
-	mmc_deselect_cards(host);
 }
 
 static unsigned int mmc_calculate_clock(struct mmc_host *host)
 {
-	struct mmc_card *card;
 	unsigned int max_dtr = host->f_max;
 
-	list_for_each_entry(card, &host->cards, node)
-		if (!mmc_card_dead(card)) {
-			if (mmc_card_highspeed(card) && mmc_card_sd(card)) {
-				if (max_dtr > card->sw_caps.hs_max_dtr)
-					max_dtr = card->sw_caps.hs_max_dtr;
-			} else if (mmc_card_highspeed(card) && !mmc_card_sd(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;
-			}
+	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),
@@ -1415,92 +1312,66 @@ static unsigned int mmc_calculate_clock(struct mmc_host *host)
  * A request for status does not cause a state change in data
  * transfer mode.
  */
-static void mmc_check_cards(struct mmc_host *host)
+static void mmc_check_card(struct mmc_card *card)
 {
-	struct list_head *l, *n;
-
-	mmc_deselect_cards(host);
+	struct mmc_command cmd;
+	int err;
 
-	list_for_each_safe(l, n, &host->cards) {
-		struct mmc_card *card = mmc_list_to_card(l);
-		struct mmc_command cmd;
-		int err;
+	BUG_ON(!card);
 
-		cmd.opcode = MMC_SEND_STATUS;
-		cmd.arg = card->rca << 16;
-		cmd.flags = MMC_RSP_R1 | MMC_CMD_AC;
+	cmd.opcode = MMC_SEND_STATUS;
+	cmd.arg = card->rca << 16;
+	cmd.flags = MMC_RSP_R1 | MMC_CMD_AC;
 
-		err = mmc_wait_for_cmd(host, &cmd, CMD_RETRIES);
-		if (err == MMC_ERR_NONE)
-			continue;
+	err = mmc_wait_for_cmd(card->host, &cmd, CMD_RETRIES);
+	if (err == MMC_ERR_NONE)
+		return;
 
-		mmc_card_set_dead(card);
-	}
+	mmc_card_set_dead(card);
 }
 
 static void mmc_setup(struct mmc_host *host)
 {
-	if (host->ios.power_mode != MMC_POWER_ON) {
-		int err;
-		u32 ocr;
-
-		host->mode = MMC_MODE_SD;
-
-		mmc_power_up(host);
-		mmc_idle_cards(host);
+	int err;
+	u32 ocr;
 
-		err = mmc_send_if_cond(host, host->ocr_avail, NULL);
-		if (err != MMC_ERR_NONE) {
-			return;
-		}
-		err = mmc_send_app_op_cond(host, 0, &ocr);
+	host->mode = MMC_MODE_SD;
 
-		/*
-		 * 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;
-		}
+	mmc_power_up(host);
+	mmc_idle_cards(host);
 
-		host->ocr = mmc_select_voltage(host, ocr);
+	err = mmc_send_if_cond(host, host->ocr_avail, NULL);
+	if (err != MMC_ERR_NONE) {
+		return;
+	}
+	err = mmc_send_app_op_cond(host, 0, &ocr);
 
-		/*
-		 * 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.
-		 */
-		if (host->ocr)
-			mmc_idle_cards(host);
-	} else {
-		host->ios.bus_mode = MMC_BUSMODE_OPENDRAIN;
-		host->ios.clock = host->f_min;
-		mmc_set_ios(host);
+	/*
+	 * If we fail to detect any SD cards then try
+	 * searching for MMC cards.
+	 */
+	if (err != MMC_ERR_NONE) {
+		host->mode = MMC_MODE_MMC;
 
-		/*
-		 * We should remember the OCR mask from the existing
-		 * cards, and detect the new cards OCR mask, combine
-		 * the two and re-select the VDD.  However, if we do
-		 * change VDD, we should do an idle, and then do a
-		 * full re-initialisation.  We would need to notify
-		 * drivers so that they can re-setup the cards as
-		 * well, while keeping their queues at bay.
-		 *
-		 * For the moment, we take the easy way out - if the
-		 * new cards don't like our currently selected VDD,
-		 * they drop off the bus.
-		 */
+		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_idle_cards(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.)
@@ -1522,7 +1393,7 @@ static void mmc_setup(struct mmc_host *host)
 		mmc_send_op_cond(host, host->ocr | (1 << 30), NULL);
 	}
 
-	mmc_discover_cards(host);
+	mmc_discover_card(host);
 
 	/*
 	 * Ok, now switch to push-pull mode.
@@ -1530,13 +1401,19 @@ static void mmc_setup(struct mmc_host *host)
 	host->ios.bus_mode = MMC_BUSMODE_PUSHPULL;
 	mmc_set_ios(host);
 
-	mmc_read_csds(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);
+	}
 
 	if (host->mode == MMC_MODE_SD) {
-		mmc_read_scrs(host);
+		mmc_read_scr(host);
 		mmc_read_switch_caps(host);
 	} else
-		mmc_process_ext_csds(host);
+		mmc_process_ext_csd(host);
 }
 
 
@@ -1566,31 +1443,29 @@ static void mmc_rescan(struct work_struct *work)
 {
 	struct mmc_host *host =
 		container_of(work, struct mmc_host, detect.work);
-	struct list_head *l, *n;
-	unsigned char power_mode;
 
 	mmc_claim_host(host);
 
 	/*
-	 * Check for removed cards and newly inserted ones. We check for
+	 * Check for removed card and newly inserted ones. We check for
 	 * removed cards first so we can intelligently re-select the VDD.
 	 */
-	power_mode = host->ios.power_mode;
-	if (power_mode == MMC_POWER_ON)
-		mmc_check_cards(host);
+	if (host->card) {
+		mmc_check_card(host->card);
 
-	mmc_setup(host);
+		mmc_release_host(host);
 
-	/*
-	 * Some broken cards process CMD1 even in stand-by state. There is
-	 * no reply, but an ILLEGAL_COMMAND error is cached and returned
-	 * after next command. We poll for card status here to clear any
-	 * possibly pending error.
-	 */
-	if (power_mode == MMC_POWER_ON)
-		mmc_check_cards(host);
+		if (mmc_card_dead(host->card)) {
+			mmc_remove_card(host->card);
+			host->card = NULL;
+		}
+
+		goto out;
+	}
 
-	if (!list_empty(&host->cards)) {
+	mmc_setup(host);
+
+	if (host->card && !mmc_card_dead(host->card)) {
 		/*
 		 * (Re-)calculate the fastest clock rate which the
 		 * attached cards and the host support.
@@ -1601,31 +1476,28 @@ static void mmc_rescan(struct work_struct *work)
 
 	mmc_release_host(host);
 
-	list_for_each_safe(l, n, &host->cards) {
-		struct mmc_card *card = mmc_list_to_card(l);
-
-		/*
-		 * If this is a new and good card, register it.
-		 */
-		if (!mmc_card_present(card) && !mmc_card_dead(card)) {
-			if (mmc_register_card(card))
-				mmc_card_set_dead(card);
-		}
+	/*
+	 * 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 (mmc_card_dead(card)) {
-			list_del(&card->node);
-			mmc_remove_card(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 (list_empty(&host->cards))
+	if (!host->card)
 		mmc_power_off(host);
 }
 
@@ -1645,7 +1517,6 @@ struct mmc_host *mmc_alloc_host(int extra, struct device *dev)
 	if (host) {
 		spin_lock_init(&host->lock);
 		init_waitqueue_head(&host->wq);
-		INIT_LIST_HEAD(&host->cards);
 		INIT_DELAYED_WORK(&host->detect, mmc_rescan);
 
 		/*
@@ -1694,8 +1565,6 @@ EXPORT_SYMBOL(mmc_add_host);
  */
 void mmc_remove_host(struct mmc_host *host)
 {
-	struct list_head *l, *n;
-
 #ifdef CONFIG_MMC_DEBUG
 	mmc_claim_host(host);
 	host->removed = 1;
@@ -1704,10 +1573,9 @@ void mmc_remove_host(struct mmc_host *host)
 
 	mmc_flush_scheduled_work();
 
-	list_for_each_safe(l, n, &host->cards) {
-		struct mmc_card *card = mmc_list_to_card(l);
-
-		mmc_remove_card(card);
+	if (host->card) {
+		mmc_remove_card(host->card);
+		host->card = NULL;
 	}
 
 	mmc_power_off(host);
@@ -1738,14 +1606,11 @@ EXPORT_SYMBOL(mmc_free_host);
  */
 int mmc_suspend_host(struct mmc_host *host, pm_message_t state)
 {
-	struct list_head *l, *n;
-
 	mmc_flush_scheduled_work();
 
-	list_for_each_safe(l, n, &host->cards) {
-		struct mmc_card *card = mmc_list_to_card(l);
-
-		mmc_remove_card(card);
+	if (host->card) {
+		mmc_remove_card(host->card);
+		host->card = NULL;
 	}
 
 	mmc_power_off(host);