diff --git a/drivers/mmc/Kconfig b/drivers/mmc/Kconfig
index c7d64c0..6c97491 100644
--- a/drivers/mmc/Kconfig
+++ b/drivers/mmc/Kconfig
@@ -19,6 +19,8 @@
 	  This is an option for use by developers; most people should
 	  say N here.  This enables MMC core and driver debugging.
 
+source "drivers/mmc/core/Kconfig"
+
 source "drivers/mmc/card/Kconfig"
 
 source "drivers/mmc/host/Kconfig"
diff --git a/drivers/mmc/core/Kconfig b/drivers/mmc/core/Kconfig
new file mode 100644
index 0000000..94222b9
--- /dev/null
+++ b/drivers/mmc/core/Kconfig
@@ -0,0 +1,17 @@
+#
+# MMC core configuration
+#
+
+config MMC_UNSAFE_RESUME
+	bool "Allow unsafe resume (DANGEROUS)"
+	depends on MMC != n
+	help
+	  If you say Y here, the MMC layer will assume that all cards
+	  stayed in their respective slots during the suspend. The
+	  normal behaviour is to remove them at suspend and
+	  redetecting them at resume. Breaking this assumption will
+	  in most cases result in data corruption.
+
+	  This option is usually just for embedded systems which use
+	  a MMC/SD card for rootfs. Most people should say N here.
+
diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index 75333a2..72c7cf4 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -677,14 +677,19 @@
 
 	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);
+		if (host->bus_ops->suspend)
+			host->bus_ops->suspend(host);
+		if (!host->bus_ops->resume) {
+			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);
 
 	return 0;
@@ -698,7 +703,19 @@
  */
 int mmc_resume_host(struct mmc_host *host)
 {
-	mmc_rescan(&host->detect.work);
+	mmc_bus_get(host);
+	if (host->bus_ops && !host->bus_dead) {
+		mmc_power_up(host);
+		BUG_ON(!host->bus_ops->resume);
+		host->bus_ops->resume(host);
+	}
+	mmc_bus_put(host);
+
+	/*
+	 * We add a slight delay here so that resume can progress
+	 * in parallel.
+	 */
+	mmc_detect_change(host, 1);
 
 	return 0;
 }
diff --git a/drivers/mmc/core/core.h b/drivers/mmc/core/core.h
index fad8edc..177264d 100644
--- a/drivers/mmc/core/core.h
+++ b/drivers/mmc/core/core.h
@@ -18,6 +18,8 @@
 struct mmc_bus_ops {
 	void (*remove)(struct mmc_host *);
 	void (*detect)(struct mmc_host *);
+	void (*suspend)(struct mmc_host *);
+	void (*resume)(struct mmc_host *);
 };
 
 void mmc_attach_bus(struct mmc_host *host, const struct mmc_bus_ops *ops);
diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
index 47449e8..619581e 100644
--- a/drivers/mmc/core/mmc.c
+++ b/drivers/mmc/core/mmc.c
@@ -229,55 +229,13 @@
 }
 
 /*
- * Host is being removed. Free up the current card.
+ * Handle the detection and initialisation of a card.
+ *
+ * In the case of a resume, "curcard" will contain the card
+ * we're trying to reinitialise.
  */
-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)
+static int mmc_sd_init_card(struct mmc_host *host, u32 ocr,
+	struct mmc_card *oldcard)
 {
 	struct mmc_card *card;
 	int err;
@@ -287,27 +245,6 @@
 	BUG_ON(!host);
 	BUG_ON(!host->claimed);
 
-	mmc_attach_bus(host, &mmc_ops);
-
-	/*
-	 * Sanity check the voltages that the card claims to
-	 * support.
-	 */
-	if (ocr & 0x7F) {
-		printk(KERN_WARNING "%s: card claims to support voltages "
-		       "below the defined range. These will be ignored.\n",
-		       mmc_hostname(host));
-		ocr &= ~0x7F;
-	}
-
-	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
@@ -317,7 +254,9 @@
 	mmc_go_idle(host);
 
 	/* The extra bit indicates that we support high capacity */
-	mmc_send_op_cond(host, host->ocr | (1 << 30), NULL);
+	err = mmc_send_op_cond(host, ocr | (1 << 30), NULL);
+	if (err != MMC_ERR_NONE)
+		goto err;
 
 	/*
 	 * Fetch CID from card.
@@ -326,16 +265,23 @@
 	if (err != MMC_ERR_NONE)
 		goto err;
 
-	/*
-	 * Allocate card structure.
-	 */
-	card = mmc_alloc_card(host);
-	if (IS_ERR(card))
-		goto err;
+	if (oldcard) {
+		if (memcmp(cid, oldcard->raw_cid, sizeof(cid)) != 0)
+			goto err;
 
-	card->type = MMC_TYPE_MMC;
-	card->rca = 1;
-	memcpy(card->raw_cid, cid, sizeof(card->raw_cid));
+		card = oldcard;
+	} else {
+		/*
+		 * 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.
@@ -346,15 +292,17 @@
 
 	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;
+	if (!oldcard) {
+		/*
+		 * 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);
+		mmc_decode_csd(card);
+		mmc_decode_cid(card);
+	}
 
 	/*
 	 * Select card, as all following commands rely on that.
@@ -363,12 +311,14 @@
 	if (err != MMC_ERR_NONE)
 		goto free_card;
 
-	/*
-	 * Fetch and process extened CSD.
-	 */
-	err = mmc_read_ext_csd(card);
-	if (err != MMC_ERR_NONE)
-		goto free_card;
+	if (!oldcard) {
+		/*
+		 * Fetch and process extened CSD.
+		 */
+		err = mmc_read_ext_csd(card);
+		if (err != MMC_ERR_NONE)
+			goto free_card;
+	}
 
 	/*
 	 * Activate high speed (if supported)
@@ -412,11 +362,157 @@
 		mmc_set_bus_width(card->host, MMC_BUS_WIDTH_4);
 	}
 
-	host->card = card;
+	if (!oldcard)
+		host->card = card;
+
+	return MMC_ERR_NONE;
+
+free_card:
+	if (!oldcard)
+		mmc_remove_card(card);
+err:
+
+	return MMC_ERR_FAILED;
+}
+
+/*
+ * 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);
 
-	err = mmc_register_card(card);
+	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);
+	}
+}
+
+#ifdef CONFIG_MMC_UNSAFE_RESUME
+
+/*
+ * Suspend callback from host.
+ */
+static void mmc_suspend(struct mmc_host *host)
+{
+	BUG_ON(!host);
+	BUG_ON(!host->card);
+
+	mmc_claim_host(host);
+	mmc_deselect_cards(host);
+	host->card->state &= ~MMC_STATE_HIGHSPEED;
+	mmc_release_host(host);
+}
+
+/*
+ * Resume callback from host.
+ *
+ * This function tries to determine if the same card is still present
+ * and, if so, restore all state to it.
+ */
+static void mmc_resume(struct mmc_host *host)
+{
+	int err;
+
+	BUG_ON(!host);
+	BUG_ON(!host->card);
+
+	mmc_claim_host(host);
+
+	err = mmc_sd_init_card(host, host->ocr, host->card);
+	if (err != MMC_ERR_NONE) {
+		mmc_remove_card(host->card);
+		host->card = NULL;
+
+		mmc_detach_bus(host);
+	}
+
+	mmc_release_host(host);
+}
+
+#else
+
+#define mmc_suspend NULL
+#define mmc_resume NULL
+
+#endif
+
+static const struct mmc_bus_ops mmc_ops = {
+	.remove = mmc_remove,
+	.detect = mmc_detect,
+	.suspend = mmc_suspend,
+	.resume = mmc_resume,
+};
+
+/*
+ * Starting point for MMC card init.
+ */
+int mmc_attach_mmc(struct mmc_host *host, u32 ocr)
+{
+	int err;
+
+	BUG_ON(!host);
+	BUG_ON(!host->claimed);
+
+	mmc_attach_bus(host, &mmc_ops);
+
+	/*
+	 * Sanity check the voltages that the card claims to
+	 * support.
+	 */
+	if (ocr & 0x7F) {
+		printk(KERN_WARNING "%s: card claims to support voltages "
+		       "below the defined range. These will be ignored.\n",
+		       mmc_hostname(host));
+		ocr &= ~0x7F;
+	}
+
+	host->ocr = mmc_select_voltage(host, ocr);
+
+	/*
+	 * Can we support the voltage of the card?
+	 */
+	if (!host->ocr)
+		goto err;
+
+	/*
+	 * Detect and init the card.
+	 */
+	err = mmc_sd_init_card(host, host->ocr, NULL);
+	if (err != MMC_ERR_NONE)
+		goto err;
+
+	mmc_release_host(host);
+
+	err = mmc_register_card(host->card);
 	if (err)
 		goto reclaim_host;
 
@@ -424,8 +520,7 @@
 
 reclaim_host:
 	mmc_claim_host(host);
-free_card:
-	mmc_remove_card(card);
+	mmc_remove_card(host->card);
 	host->card = NULL;
 err:
 	mmc_detach_bus(host);
diff --git a/drivers/mmc/core/sd.c b/drivers/mmc/core/sd.c
index ae54e8e..6597e77 100644
--- a/drivers/mmc/core/sd.c
+++ b/drivers/mmc/core/sd.c
@@ -263,6 +263,161 @@
 }
 
 /*
+ * Handle the detection and initialisation of a card.
+ *
+ * In the case of a resume, "curcard" will contain the card
+ * we're trying to reinitialise.
+ */
+static int mmc_sd_init_card(struct mmc_host *host, u32 ocr,
+	struct mmc_card *oldcard)
+{
+	struct mmc_card *card;
+	int err;
+	u32 cid[4];
+	unsigned int max_dtr;
+
+	BUG_ON(!host);
+	BUG_ON(!host->claimed);
+
+	/*
+	 * 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, ocr);
+	if (err == MMC_ERR_NONE)
+		ocr |= 1 << 30;
+
+	err = mmc_send_app_op_cond(host, ocr, NULL);
+	if (err != MMC_ERR_NONE)
+		goto err;
+
+	/*
+	 * Fetch CID from card.
+	 */
+	err = mmc_all_send_cid(host, cid);
+	if (err != MMC_ERR_NONE)
+		goto err;
+
+	if (oldcard) {
+		if (memcmp(cid, oldcard->raw_cid, sizeof(cid)) != 0)
+			goto err;
+
+		card = oldcard;
+	} else {
+		/*
+		 * 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);
+
+	if (!oldcard) {
+		/*
+		 * 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);
+	}
+
+	/*
+	 * Select card, as all following commands rely on that.
+	 */
+	err = mmc_select_card(card);
+	if (err != MMC_ERR_NONE)
+		goto free_card;
+
+	if (!oldcard) {
+		/*
+		 * Fetch SCR from card.
+		 */
+		err = mmc_app_send_scr(card, card->raw_scr);
+		if (err != MMC_ERR_NONE)
+			goto free_card;
+
+		mmc_decode_scr(card);
+
+		/*
+		 * Fetch switch information from card.
+		 */
+		err = mmc_read_switch(card);
+		if (err != MMC_ERR_NONE)
+			goto free_card;
+	}
+
+	/*
+	 * Attempt to change to high-speed (if supported)
+	 */
+	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);
+	}
+
+	if (!oldcard)
+		host->card = card;
+
+	return MMC_ERR_NONE;
+
+free_card:
+	if (!oldcard)
+		mmc_remove_card(card);
+err:
+
+	return MMC_ERR_FAILED;
+}
+
+/*
  * Host is being removed. Free up the current card.
  */
 static void mmc_sd_remove(struct mmc_host *host)
@@ -303,9 +458,60 @@
 	}
 }
 
+#ifdef CONFIG_MMC_UNSAFE_RESUME
+
+/*
+ * Suspend callback from host.
+ */
+static void mmc_sd_suspend(struct mmc_host *host)
+{
+	BUG_ON(!host);
+	BUG_ON(!host->card);
+
+	mmc_claim_host(host);
+	mmc_deselect_cards(host);
+	host->card->state &= ~MMC_STATE_HIGHSPEED;
+	mmc_release_host(host);
+}
+
+/*
+ * Resume callback from host.
+ *
+ * This function tries to determine if the same card is still present
+ * and, if so, restore all state to it.
+ */
+static void mmc_sd_resume(struct mmc_host *host)
+{
+	int err;
+
+	BUG_ON(!host);
+	BUG_ON(!host->card);
+
+	mmc_claim_host(host);
+
+	err = mmc_sd_init_card(host, host->ocr, host->card);
+	if (err != MMC_ERR_NONE) {
+		mmc_remove_card(host->card);
+		host->card = NULL;
+
+		mmc_detach_bus(host);
+	}
+
+	mmc_release_host(host);
+}
+
+#else
+
+#define mmc_sd_suspend NULL
+#define mmc_sd_resume NULL
+
+#endif
+
 static const struct mmc_bus_ops mmc_sd_ops = {
 	.remove = mmc_sd_remove,
 	.detect = mmc_sd_detect,
+	.suspend = mmc_sd_suspend,
+	.resume = mmc_sd_resume,
 };
 
 /*
@@ -313,10 +519,7 @@
  */
 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);
@@ -350,119 +553,15 @@
 		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.
+	 * Detect and init the card.
 	 */
-	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);
+	err = mmc_sd_init_card(host, host->ocr, NULL);
 	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);
-
-	/*
-	 * Fetch switch information from card.
-	 */
-	err = mmc_read_switch(card);
-	if (err != MMC_ERR_NONE)
-		goto free_card;
-
-	/*
-	 * Attempt to change to high-speed (if supported)
-	 */
-	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);
+	err = mmc_register_card(host->card);
 	if (err)
 		goto reclaim_host;
 
@@ -470,8 +569,7 @@
 
 reclaim_host:
 	mmc_claim_host(host);
-free_card:
-	mmc_remove_card(card);
+	mmc_remove_card(host->card);
 	host->card = NULL;
 err:
 	mmc_detach_bus(host);