[ARM] 3456/1: AT91RM9200 support for 2.6 (MMC/SD driver)

Patch from Andrew Victor

This patch adds support for the MMC/SD card interface on the Atmel
AT91RM9200 processor.

Original driver was by Nick Randell, but a number of people have
subsequently worked on it. It's currently maintained by Malcolm Noyes.

Signed-off-by: Andrew Victor <andrew@sanpeople.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

3 files changed, 997 insertions, 0 deletions

diff --git a/drivers/mmc/Kconfig b/drivers/mmc/Kconfig
index 7cc162e8978..0330168e50c 100644
--- a/drivers/mmc/Kconfig
+++ b/drivers/mmc/Kconfig
@@ -91,4 +91,12 @@ config MMC_AU1X
 
 	  If unsure, say N.
 
+config MMC_AT91RM9200
+	tristate "AT91RM9200 SD/MMC Card Interface support"
+	depends on ARCH_AT91RM9200 && MMC
+	help
+	  This selects the AT91RM9200 MCI controller.
+
+	  If unsure, say N.
+
 endmenu
diff --git a/drivers/mmc/Makefile b/drivers/mmc/Makefile
index c7c34aadfc9..5d2b9ab59c4 100644
--- a/drivers/mmc/Makefile
+++ b/drivers/mmc/Makefile
@@ -21,6 +21,7 @@ obj-$(CONFIG_MMC_SDHCI)		+= sdhci.o
 obj-$(CONFIG_MMC_WBSD)		+= wbsd.o
 obj-$(CONFIG_MMC_AU1X)		+= au1xmmc.o
 obj-$(CONFIG_MMC_OMAP)		+= omap.o
+obj-$(CONFIG_MMC_AT91RM9200)	+= at91_mci.o
 
 mmc_core-y := mmc.o mmc_queue.o mmc_sysfs.o
 
diff --git a/drivers/mmc/at91_mci.c b/drivers/mmc/at91_mci.c
new file mode 100644
index 00000000000..6061c2d101a
--- /dev/null
+++ b/drivers/mmc/at91_mci.c
@@ -0,0 +1,988 @@
+/*
+ *  linux/drivers/mmc/at91_mci.c - ATMEL AT91RM9200 MCI Driver
+ *
+ *  Copyright (C) 2005 Cougar Creek Computing Devices Ltd, All Rights Reserved
+ *
+ *  Copyright (C) 2006 Malcolm Noyes
+ *
+ * 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.
+ */
+
+/*
+   This is the AT91RM9200 MCI driver that has been tested with both MMC cards
+   and SD-cards.  Boards that support write protect are now supported.
+   The CCAT91SBC001 board does not support SD cards.
+
+   The three entry points are at91_mci_request, at91_mci_set_ios
+   and at91_mci_get_ro.
+
+   SET IOS
+     This configures the device to put it into the correct mode and clock speed
+     required.
+
+   MCI REQUEST
+     MCI request processes the commands sent in the mmc_request structure. This
+     can consist of a processing command and a stop command in the case of
+     multiple block transfers.
+
+     There are three main types of request, commands, reads and writes.
+
+     Commands are straight forward. The command is submitted to the controller and
+     the request function returns. When the controller generates an interrupt to indicate
+     the command is finished, the response to the command are read and the mmc_request_done
+     function called to end the request.
+
+     Reads and writes work in a similar manner to normal commands but involve the PDC (DMA)
+     controller to manage the transfers.
+
+     A read is done from the controller directly to the scatterlist passed in from the request.
+     Due to a bug in the controller, when a read is completed, all the words are byte
+     swapped in the scatterlist buffers.
+
+     The sequence of read interrupts is: ENDRX, RXBUFF, CMDRDY
+
+     A write is slightly different in that the bytes to write are read from the scatterlist
+     into a dma memory buffer (this is in case the source buffer should be read only). The
+     entire write buffer is then done from this single dma memory buffer.
+
+     The sequence of write interrupts is: ENDTX, TXBUFE, NOTBUSY, CMDRDY
+
+   GET RO
+     Gets the status of the write protect pin, if available.
+*/
+
+#include <linux/config.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/init.h>
+#include <linux/ioport.h>
+#include <linux/platform_device.h>
+#include <linux/interrupt.h>
+#include <linux/blkdev.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/dma-mapping.h>
+#include <linux/clk.h>
+
+#include <linux/mmc/host.h>
+#include <linux/mmc/protocol.h>
+
+#include <asm/io.h>
+#include <asm/irq.h>
+#include <asm/mach/mmc.h>
+#include <asm/arch/board.h>
+#include <asm/arch/gpio.h>
+#include <asm/arch/at91rm9200_mci.h>
+#include <asm/arch/at91rm9200_pdc.h>
+
+#define DRIVER_NAME "at91_mci"
+
+#undef	SUPPORT_4WIRE
+
+#ifdef CONFIG_MMC_DEBUG
+#define DBG(fmt...)	\
+	printk(fmt)
+#else
+#define DBG(fmt...)	do { } while (0)
+#endif
+
+static struct clk *mci_clk;
+
+#define FL_SENT_COMMAND (1 << 0)
+#define FL_SENT_STOP (1 << 1)
+
+
+
+/*
+ * Read from a MCI register.
+ */
+static inline unsigned long at91_mci_read(unsigned int reg)
+{
+	void __iomem *mci_base = (void __iomem *)AT91_VA_BASE_MCI;
+
+	return __raw_readl(mci_base + reg);
+}
+
+/*
+ * Write to a MCI register.
+ */
+static inline void at91_mci_write(unsigned int reg, unsigned long value)
+{
+        void __iomem *mci_base = (void __iomem *)AT91_VA_BASE_MCI;
+
+        __raw_writel(value, mci_base + reg);
+}
+
+/*
+ * Low level type for this driver
+ */
+struct at91mci_host
+{
+	struct mmc_host *mmc;
+	struct mmc_command *cmd;
+	struct mmc_request *request;
+
+	struct at91_mmc_data *board;
+	int present;
+
+	/*
+	 * Flag indicating when the command has been sent. This is used to
+	 * work out whether or not to send the stop
+	 */
+	unsigned int flags;
+	/* flag for current bus settings */
+	u32 bus_mode;
+
+	/* DMA buffer used for transmitting */
+	unsigned int* buffer;
+	dma_addr_t physical_address;
+	unsigned int total_length;
+
+	/* Latest in the scatterlist that has been enabled for transfer, but not freed */
+	int in_use_index;
+
+	/* Latest in the scatterlist that has been enabled for transfer */
+	int transfer_index;
+};
+
+/*
+ * Copy from sg to a dma block - used for transfers
+ */
+static inline void at91mci_sg_to_dma(struct at91mci_host *host, struct mmc_data *data)
+{
+	unsigned int len, i, size;
+	unsigned *dmabuf = host->buffer;
+
+	size = host->total_length;
+	len = data->sg_len;
+
+	/*
+	 * Just loop through all entries. Size might not
+	 * be the entire list though so make sure that
+	 * we do not transfer too much.
+	 */
+	for (i = 0; i < len; i++) {
+		struct scatterlist *sg;
+		int amount;
+		int index;
+		unsigned int *sgbuffer;
+
+		sg = &data->sg[i];
+
+		sgbuffer = kmap_atomic(sg->page, KM_BIO_SRC_IRQ) + sg->offset;
+		amount = min(size, sg->length);
+		size -= amount;
+		amount /= 4;
+
+		for (index = 0; index < amount; index++)
+			*dmabuf++ = swab32(sgbuffer[index]);
+
+		kunmap_atomic(sgbuffer, KM_BIO_SRC_IRQ);
+
+		if (size == 0)
+			break;
+	}
+
+	/*
+	 * Check that we didn't get a request to transfer
+	 * more data than can fit into the SG list.
+	 */
+	BUG_ON(size != 0);
+}
+
+/*
+ * Prepare a dma read
+ */
+static void at91mci_pre_dma_read(struct at91mci_host *host)
+{
+	int i;
+	struct scatterlist *sg;
+	struct mmc_command *cmd;
+	struct mmc_data *data;
+
+	DBG("pre dma read\n");
+
+	cmd = host->cmd;
+	if (!cmd) {
+		DBG("no command\n");
+		return;
+	}
+
+	data = cmd->data;
+	if (!data) {
+		DBG("no data\n");
+		return;
+	}
+
+	for (i = 0; i < 2; i++) {
+		/* nothing left to transfer */
+		if (host->transfer_index >= data->sg_len) {
+			DBG("Nothing left to transfer (index = %d)\n", host->transfer_index);
+			break;
+		}
+
+		/* Check to see if this needs filling */
+		if (i == 0) {
+			if (at91_mci_read(AT91_PDC_RCR) != 0) {
+				DBG("Transfer active in current\n");
+				continue;
+			}
+		}
+		else {
+			if (at91_mci_read(AT91_PDC_RNCR) != 0) {
+				DBG("Transfer active in next\n");
+				continue;
+			}
+		}
+
+		/* Setup the next transfer */
+		DBG("Using transfer index %d\n", host->transfer_index);
+
+		sg = &data->sg[host->transfer_index++];
+		DBG("sg = %p\n", sg);
+
+		sg->dma_address = dma_map_page(NULL, sg->page, sg->offset, sg->length, DMA_FROM_DEVICE);
+
+		DBG("dma address = %08X, length = %d\n", sg->dma_address, sg->length);
+
+		if (i == 0) {
+			at91_mci_write(AT91_PDC_RPR, sg->dma_address);
+			at91_mci_write(AT91_PDC_RCR, sg->length / 4);
+		}
+		else {
+			at91_mci_write(AT91_PDC_RNPR, sg->dma_address);
+			at91_mci_write(AT91_PDC_RNCR, sg->length / 4);
+		}
+	}
+
+	DBG("pre dma read done\n");
+}
+
+/*
+ * Handle after a dma read
+ */
+static void at91mci_post_dma_read(struct at91mci_host *host)
+{
+	struct mmc_command *cmd;
+	struct mmc_data *data;
+
+	DBG("post dma read\n");
+
+	cmd = host->cmd;
+	if (!cmd) {
+		DBG("no command\n");
+		return;
+	}
+
+	data = cmd->data;
+	if (!data) {
+		DBG("no data\n");
+		return;
+	}
+
+	while (host->in_use_index < host->transfer_index) {
+		unsigned int *buffer;
+		int index;
+		int len;
+
+		struct scatterlist *sg;
+
+		DBG("finishing index %d\n", host->in_use_index);
+
+		sg = &data->sg[host->in_use_index++];
+
+		DBG("Unmapping page %08X\n", sg->dma_address);
+
+		dma_unmap_page(NULL, sg->dma_address, sg->length, DMA_FROM_DEVICE);
+
+		/* Swap the contents of the buffer */
+		buffer = kmap_atomic(sg->page, KM_BIO_SRC_IRQ) + sg->offset;
+		DBG("buffer = %p, length = %d\n", buffer, sg->length);
+
+		data->bytes_xfered += sg->length;
+
+		len = sg->length / 4;
+
+		for (index = 0; index < len; index++) {
+			buffer[index] = swab32(buffer[index]);
+		}
+		kunmap_atomic(buffer, KM_BIO_SRC_IRQ);
+		flush_dcache_page(sg->page);
+	}
+
+	/* Is there another transfer to trigger? */
+	if (host->transfer_index < data->sg_len)
+		at91mci_pre_dma_read(host);
+	else {
+		at91_mci_write(AT91_MCI_IER, AT91_MCI_RXBUFF);
+		at91_mci_write(AT91_PDC_PTCR, AT91_PDC_RXTDIS | AT91_PDC_TXTDIS);
+	}
+
+	DBG("post dma read done\n");
+}
+
+/*
+ * Handle transmitted data
+ */
+static void at91_mci_handle_transmitted(struct at91mci_host *host)
+{
+	struct mmc_command *cmd;
+	struct mmc_data *data;
+
+	DBG("Handling the transmit\n");
+
+	/* Disable the transfer */
+	at91_mci_write(AT91_PDC_PTCR, AT91_PDC_RXTDIS | AT91_PDC_TXTDIS);
+
+	/* Now wait for cmd ready */
+	at91_mci_write(AT91_MCI_IDR, AT91_MCI_TXBUFE);
+	at91_mci_write(AT91_MCI_IER, AT91_MCI_NOTBUSY);
+
+	cmd = host->cmd;
+	if (!cmd) return;
+
+	data = cmd->data;
+	if (!data) return;
+
+	data->bytes_xfered = host->total_length;
+}
+
+/*
+ * Enable the controller
+ */
+static void at91_mci_enable(void)
+{
+	at91_mci_write(AT91_MCI_CR, AT91_MCI_MCIEN);
+	at91_mci_write(AT91_MCI_IDR, 0xFFFFFFFF);
+	at91_mci_write(AT91_MCI_DTOR, AT91_MCI_DTOMUL_1M | AT91_MCI_DTOCYC);
+	at91_mci_write(AT91_MCI_MR, 0x834A);
+	at91_mci_write(AT91_MCI_SDCR, 0x0);
+}
+
+/*
+ * Disable the controller
+ */
+static void at91_mci_disable(void)
+{
+	at91_mci_write(AT91_MCI_CR, AT91_MCI_MCIDIS | AT91_MCI_SWRST);
+}
+
+/*
+ * Send a command
+ * return the interrupts to enable
+ */
+static unsigned int at91_mci_send_command(struct at91mci_host *host, struct mmc_command *cmd)
+{
+	unsigned int cmdr, mr;
+	unsigned int block_length;
+	struct mmc_data *data = cmd->data;
+
+	unsigned int blocks;
+	unsigned int ier = 0;
+
+	host->cmd = cmd;
+
+	/* Not sure if this is needed */
+#if 0
+	if ((at91_mci_read(AT91_MCI_SR) & AT91_MCI_RTOE) && (cmd->opcode == 1)) {
+		DBG("Clearing timeout\n");
+		at91_mci_write(AT91_MCI_ARGR, 0);
+		at91_mci_write(AT91_MCI_CMDR, AT91_MCI_OPDCMD);
+		while (!(at91_mci_read(AT91_MCI_SR) & AT91_MCI_CMDRDY)) {
+			/* spin */
+			DBG("Clearing: SR = %08X\n", at91_mci_read(AT91_MCI_SR));
+		}
+	}
+#endif
+	cmdr = cmd->opcode;
+
+	if (mmc_resp_type(cmd) == MMC_RSP_NONE)
+		cmdr |= AT91_MCI_RSPTYP_NONE;
+	else {
+		/* if a response is expected then allow maximum response latancy */
+		cmdr |= AT91_MCI_MAXLAT;
+		/* set 136 bit response for R2, 48 bit response otherwise */
+		if (mmc_resp_type(cmd) == MMC_RSP_R2)
+			cmdr |= AT91_MCI_RSPTYP_136;
+		else
+			cmdr |= AT91_MCI_RSPTYP_48;
+	}
+
+	if (data) {
+		block_length = 1 << data->blksz_bits;
+		blocks = data->blocks;
+
+		/* always set data start - also set direction flag for read */
+		if (data->flags & MMC_DATA_READ)
+			cmdr |= (AT91_MCI_TRDIR | AT91_MCI_TRCMD_START);
+		else if (data->flags & MMC_DATA_WRITE)
+			cmdr |= AT91_MCI_TRCMD_START;
+
+		if (data->flags & MMC_DATA_STREAM)
+			cmdr |= AT91_MCI_TRTYP_STREAM;
+		if (data->flags & MMC_DATA_MULTI)
+			cmdr |= AT91_MCI_TRTYP_MULTIPLE;
+	}
+	else {
+		block_length = 0;
+		blocks = 0;
+	}
+
+	if (cmd->opcode == MMC_STOP_TRANSMISSION)
+		cmdr |= AT91_MCI_TRCMD_STOP;
+
+	if (host->bus_mode == MMC_BUSMODE_OPENDRAIN)
+		cmdr |= AT91_MCI_OPDCMD;
+
+	/*
+	 * Set the arguments and send the command
+	 */
+	DBG("Sending command %d as %08X, arg = %08X, blocks = %d, length = %d (MR = %08lX)\n",
+		cmd->opcode, cmdr, cmd->arg, blocks, block_length, at91_mci_read(AT91_MCI_MR));
+
+	if (!data) {
+		at91_mci_write(AT91_PDC_PTCR, AT91_PDC_TXTDIS | AT91_PDC_RXTDIS);
+		at91_mci_write(AT91_PDC_RPR, 0);
+		at91_mci_write(AT91_PDC_RCR, 0);
+		at91_mci_write(AT91_PDC_RNPR, 0);
+		at91_mci_write(AT91_PDC_RNCR, 0);
+		at91_mci_write(AT91_PDC_TPR, 0);
+		at91_mci_write(AT91_PDC_TCR, 0);
+		at91_mci_write(AT91_PDC_TNPR, 0);
+		at91_mci_write(AT91_PDC_TNCR, 0);
+
+		at91_mci_write(AT91_MCI_ARGR, cmd->arg);
+		at91_mci_write(AT91_MCI_CMDR, cmdr);
+		return AT91_MCI_CMDRDY;
+	}
+
+	mr = at91_mci_read(AT91_MCI_MR) & 0x7fff;	/* zero block length and PDC mode */
+	at91_mci_write(AT91_MCI_MR, mr | (block_length << 16) | AT91_MCI_PDCMODE);
+
+	/*
+	 * Disable the PDC controller
+	 */
+	at91_mci_write(AT91_PDC_PTCR, AT91_PDC_RXTDIS | AT91_PDC_TXTDIS);
+
+	if (cmdr & AT91_MCI_TRCMD_START) {
+		data->bytes_xfered = 0;
+		host->transfer_index = 0;
+		host->in_use_index = 0;
+		if (cmdr & AT91_MCI_TRDIR) {
+			/*
+			 * Handle a read
+			 */
+			host->buffer = NULL;
+			host->total_length = 0;
+
+			at91mci_pre_dma_read(host);
+			ier = AT91_MCI_ENDRX /* | AT91_MCI_RXBUFF */;
+		}
+		else {
+			/*
+			 * Handle a write
+			 */
+			host->total_length = block_length * blocks;
+			host->buffer = dma_alloc_coherent(NULL,
+						  host->total_length,
+						  &host->physical_address, GFP_KERNEL);
+
+			at91mci_sg_to_dma(host, data);
+
+			DBG("Transmitting %d bytes\n", host->total_length);
+
+			at91_mci_write(AT91_PDC_TPR, host->physical_address);
+			at91_mci_write(AT91_PDC_TCR, host->total_length / 4);
+			ier = AT91_MCI_TXBUFE;
+		}
+	}
+
+	/*
+	 * Send the command and then enable the PDC - not the other way round as
+	 * the data sheet says
+	 */
+
+	at91_mci_write(AT91_MCI_ARGR, cmd->arg);
+	at91_mci_write(AT91_MCI_CMDR, cmdr);
+
+	if (cmdr & AT91_MCI_TRCMD_START) {
+		if (cmdr & AT91_MCI_TRDIR)
+			at91_mci_write(AT91_PDC_PTCR, AT91_PDC_RXTEN);
+		else
+			at91_mci_write(AT91_PDC_PTCR, AT91_PDC_TXTEN);
+	}
+	return ier;
+}
+
+/*
+ * Wait for a command to complete
+ */
+static void at91mci_process_command(struct at91mci_host *host, struct mmc_command *cmd)
+{
+	unsigned int ier;
+
+	ier = at91_mci_send_command(host, cmd);
+
+	DBG("setting ier to %08X\n", ier);
+
+	/* Stop on errors or the required value */
+	at91_mci_write(AT91_MCI_IER, 0xffff0000 | ier);
+}
+
+/*
+ * Process the next step in the request
+ */
+static void at91mci_process_next(struct at91mci_host *host)
+{
+	if (!(host->flags & FL_SENT_COMMAND)) {
+		host->flags |= FL_SENT_COMMAND;
+		at91mci_process_command(host, host->request->cmd);
+	}
+	else if ((!(host->flags & FL_SENT_STOP)) && host->request->stop) {
+		host->flags |= FL_SENT_STOP;
+		at91mci_process_command(host, host->request->stop);
+	}
+	else
+		mmc_request_done(host->mmc, host->request);
+}
+
+/*
+ * Handle a command that has been completed
+ */
+static void at91mci_completed_command(struct at91mci_host *host)
+{
+	struct mmc_command *cmd = host->cmd;
+	unsigned int status;
+
+	at91_mci_write(AT91_MCI_IDR, 0xffffffff);
+
+	cmd->resp[0] = at91_mci_read(AT91_MCI_RSPR(0));
+	cmd->resp[1] = at91_mci_read(AT91_MCI_RSPR(1));
+	cmd->resp[2] = at91_mci_read(AT91_MCI_RSPR(2));
+	cmd->resp[3] = at91_mci_read(AT91_MCI_RSPR(3));
+
+	if (host->buffer) {
+		dma_free_coherent(NULL, host->total_length, host->buffer, host->physical_address);
+		host->buffer = NULL;
+	}
+
+	status = at91_mci_read(AT91_MCI_SR);
+
+	DBG("Status = %08X [%08X %08X %08X %08X]\n",
+		 status, cmd->resp[0], cmd->resp[1], cmd->resp[2], cmd->resp[3]);
+
+	if (status & (AT91_MCI_RINDE | AT91_MCI_RDIRE | AT91_MCI_RCRCE |
+			AT91_MCI_RENDE | AT91_MCI_RTOE | AT91_MCI_DCRCE |
+			AT91_MCI_DTOE | AT91_MCI_OVRE | AT91_MCI_UNRE)) {
+		if ((status & AT91_MCI_RCRCE) &&
+			((cmd->opcode == MMC_SEND_OP_COND) || (cmd->opcode == SD_APP_OP_COND))) {
+			cmd->error = MMC_ERR_NONE;
+		}
+		else {
+			if (status & (AT91_MCI_RTOE | AT91_MCI_DTOE))
+				cmd->error = MMC_ERR_TIMEOUT;
+			else if (status & (AT91_MCI_RCRCE | AT91_MCI_DCRCE))
+				cmd->error = MMC_ERR_BADCRC;
+			else if (status & (AT91_MCI_OVRE | AT91_MCI_UNRE))
+				cmd->error = MMC_ERR_FIFO;
+			else
+				cmd->error = MMC_ERR_FAILED;
+
+			DBG("Error detected and set to %d (cmd = %d, retries = %d)\n",
+				 cmd->error, cmd->opcode, cmd->retries);
+		}
+	}
+	else
+		cmd->error = MMC_ERR_NONE;
+
+	at91mci_process_next(host);
+}
+
+/*
+ * Handle an MMC request
+ */
+static void at91_mci_request(struct mmc_host *mmc, struct mmc_request *mrq)
+{
+	struct at91mci_host *host = mmc_priv(mmc);
+	host->request = mrq;
+	host->flags = 0;
+
+	at91mci_process_next(host);
+}
+
+/*
+ * Set the IOS
+ */
+static void at91_mci_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
+{
+	int clkdiv;
+	struct at91mci_host *host = mmc_priv(mmc);
+	unsigned long at91_master_clock = clk_get_rate(mci_clk);
+
+	DBG("Clock %uHz, busmode %u, powermode %u, Vdd %u\n",
+		ios->clock, ios->bus_mode, ios->power_mode, ios->vdd);
+
+	if (host)
+		host->bus_mode = ios->bus_mode;
+	else
+		printk("MMC: No host for bus_mode\n");
+
+	if (ios->clock == 0) {
+		/* Disable the MCI controller */
+		at91_mci_write(AT91_MCI_CR, AT91_MCI_MCIDIS);
+		clkdiv = 0;
+	}
+	else {
+		/* Enable the MCI controller */
+		at91_mci_write(AT91_MCI_CR, AT91_MCI_MCIEN);
+
+		if ((at91_master_clock % (ios->clock * 2)) == 0)
+			clkdiv = ((at91_master_clock / ios->clock) / 2) - 1;
+		else
+			clkdiv = (at91_master_clock / ios->clock) / 2;
+
+		DBG("clkdiv = %d. mcck = %ld\n", clkdiv,
+			at91_master_clock / (2 * (clkdiv + 1)));
+	}
+	if (ios->bus_width == MMC_BUS_WIDTH_4 && host->board->wire4) {
+		DBG("MMC: Setting controller bus width to 4\n");
+		at91_mci_write(AT91_MCI_SDCR, at91_mci_read(AT91_MCI_SDCR) | AT91_MCI_SDCBUS);
+	}
+	else {
+		DBG("MMC: Setting controller bus width to 1\n");
+		at91_mci_write(AT91_MCI_SDCR, at91_mci_read(AT91_MCI_SDCR) & ~AT91_MCI_SDCBUS);
+	}
+
+	/* Set the clock divider */
+	at91_mci_write(AT91_MCI_MR, (at91_mci_read(AT91_MCI_MR) & ~AT91_MCI_CLKDIV) | clkdiv);
+
+	/* maybe switch power to the card */
+	if (host && host->board->vcc_pin) {
+		switch (ios->power_mode) {
+			case MMC_POWER_OFF:
+				at91_set_gpio_output(host->board->vcc_pin, 0);
+				break;
+			case MMC_POWER_UP:
+			case MMC_POWER_ON:
+				at91_set_gpio_output(host->board->vcc_pin, 1);
+				break;
+		}
+	}
+}
+
+/*
+ * Handle an interrupt
+ */
+static irqreturn_t at91_mci_irq(int irq, void *devid, struct pt_regs *regs)
+{
+	struct at91mci_host *host = devid;
+	int completed = 0;
+
+	unsigned int int_status;
+
+	if (host == NULL)
+		return IRQ_HANDLED;
+
+	int_status = at91_mci_read(AT91_MCI_SR);
+	DBG("MCI irq: status = %08X, %08lX, %08lX\n", int_status, at91_mci_read(AT91_MCI_IMR),
+		int_status & at91_mci_read(AT91_MCI_IMR));
+
+	if ((int_status & at91_mci_read(AT91_MCI_IMR)) & 0xffff0000)
+		completed = 1;
+
+	int_status &= at91_mci_read(AT91_MCI_IMR);
+
+	if (int_status & AT91_MCI_UNRE)
+		DBG("MMC: Underrun error\n");
+	if (int_status & AT91_MCI_OVRE)
+		DBG("MMC: Overrun error\n");
+	if (int_status & AT91_MCI_DTOE)
+		DBG("MMC: Data timeout\n");
+	if (int_status & AT91_MCI_DCRCE)
+		DBG("MMC: CRC error in data\n");
+	if (int_status & AT91_MCI_RTOE)
+		DBG("MMC: Response timeout\n");
+	if (int_status & AT91_MCI_RENDE)
+		DBG("MMC: Response end bit error\n");
+	if (int_status & AT91_MCI_RCRCE)
+		DBG("MMC: Response CRC error\n");
+	if (int_status & AT91_MCI_RDIRE)
+		DBG("MMC: Response direction error\n");
+	if (int_status & AT91_MCI_RINDE)
+		DBG("MMC: Response index error\n");
+
+	/* Only continue processing if no errors */
+	if (!completed) {
+		if (int_status & AT91_MCI_TXBUFE) {
+			DBG("TX buffer empty\n");
+			at91_mci_handle_transmitted(host);
+		}
+
+		if (int_status & AT91_MCI_RXBUFF) {
+			DBG("RX buffer full\n");
+			at91_mci_write(AT91_MCI_IER, AT91_MCI_CMDRDY);
+		}
+
+		if (int_status & AT91_MCI_ENDTX) {
+			DBG("Transmit has ended\n");
+		}
+
+		if (int_status & AT91_MCI_ENDRX) {
+			DBG("Receive has ended\n");
+			at91mci_post_dma_read(host);
+		}
+
+		if (int_status & AT91_MCI_NOTBUSY) {
+			DBG("Card is ready\n");
+			at91_mci_write(AT91_MCI_IER, AT91_MCI_CMDRDY);
+		}
+
+		if (int_status & AT91_MCI_DTIP) {
+			DBG("Data transfer in progress\n");
+		}
+
+		if (int_status & AT91_MCI_BLKE) {
+			DBG("Block transfer has ended\n");
+		}
+
+		if (int_status & AT91_MCI_TXRDY) {
+			DBG("Ready to transmit\n");
+		}
+
+		if (int_status & AT91_MCI_RXRDY) {
+			DBG("Ready to receive\n");
+		}
+
+		if (int_status & AT91_MCI_CMDRDY) {
+			DBG("Command ready\n");
+			completed = 1;
+		}
+	}
+	at91_mci_write(AT91_MCI_IDR, int_status);
+
+	if (completed) {
+		DBG("Completed command\n");
+		at91_mci_write(AT91_MCI_IDR, 0xffffffff);
+		at91mci_completed_command(host);
+	}
+
+	return IRQ_HANDLED;
+}
+
+static irqreturn_t at91_mmc_det_irq(int irq, void *_host, struct pt_regs *regs)
+{
+	struct at91mci_host *host = _host;
+	int present = !at91_get_gpio_value(irq);
+
+	/*
+	 * we expect this irq on both insert and remove,
+	 * and use a short delay to debounce.
+	 */
+	if (present != host->present) {
+		host->present = present;
+		DBG("%s: card %s\n", mmc_hostname(host->mmc),
+			present ? "insert" : "remove");
+		if (!present) {
+			DBG("****** Resetting SD-card bus width ******\n");
+			at91_mci_write(AT91_MCI_SDCR, 0);
+		}
+		mmc_detect_change(host->mmc, msecs_to_jiffies(100));
+	}
+	return IRQ_HANDLED;
+}
+
+int at91_mci_get_ro(struct mmc_host *mmc)
+{
+	int read_only = 0;
+	struct at91mci_host *host = mmc_priv(mmc);
+
+	if (host->board->wp_pin) {
+		read_only = at91_get_gpio_value(host->board->wp_pin);
+		printk(KERN_WARNING "%s: card is %s\n", mmc_hostname(mmc),
+				(read_only ? "read-only" : "read-write") );
+	}
+	else {
+		printk(KERN_WARNING "%s: host does not support reading read-only "
+				"switch.  Assuming write-enable.\n", mmc_hostname(mmc));
+	}
+	return read_only;
+}
+
+static struct mmc_host_ops at91_mci_ops = {
+	.request	= at91_mci_request,
+	.set_ios	= at91_mci_set_ios,
+	.get_ro		= at91_mci_get_ro,
+};
+
+/*
+ * Probe for the device
+ */
+static int at91_mci_probe(struct platform_device *pdev)
+{
+	struct mmc_host *mmc;
+	struct at91mci_host *host;
+	int ret;
+
+	DBG("Probe MCI devices\n");
+	at91_mci_disable();
+	at91_mci_enable();
+
+	mmc = mmc_alloc_host(sizeof(struct at91mci_host), &pdev->dev);
+	if (!mmc) {
+		DBG("Failed to allocate mmc host\n");
+		return -ENOMEM;
+	}
+
+	mmc->ops = &at91_mci_ops;
+	mmc->f_min = 375000;
+	mmc->f_max = 25000000;
+	mmc->ocr_avail = MMC_VDD_32_33 | MMC_VDD_33_34;
+
+	host = mmc_priv(mmc);
+	host->mmc = mmc;
+	host->buffer = NULL;
+	host->bus_mode = 0;
+	host->board = pdev->dev.platform_data;
+	if (host->board->wire4) {
+#ifdef SUPPORT_4WIRE
+		mmc->caps |= MMC_CAP_4_BIT_DATA;
+#else
+		printk("MMC: 4 wire bus mode not supported by this driver - using 1 wire\n");
+#endif
+	}
+
+	/*
+	 * Get Clock
+	 */
+	mci_clk = clk_get(&pdev->dev, "mci_clk");
+	if (!mci_clk) {
+		printk(KERN_ERR "AT91 MMC: no clock defined.\n");
+		return -ENODEV;
+	}
+	clk_enable(mci_clk);			/* Enable the peripheral clock */
+
+	/*
+	 * Allocate the MCI interrupt
+	 */
+	ret = request_irq(AT91_ID_MCI, at91_mci_irq, SA_SHIRQ, DRIVER_NAME, host);
+	if (ret) {
+		DBG("Failed to request MCI interrupt\n");
+		return ret;
+	}
+
+	platform_set_drvdata(pdev, mmc);
+
+	/*
+	 * Add host to MMC layer
+	 */
+	if (host->board->det_pin)
+		host->present = !at91_get_gpio_value(host->board->det_pin);
+	else
+		host->present = -1;
+
+	mmc_add_host(mmc);
+
+	/*
+	 * monitor card insertion/removal if we can
+	 */
+	if (host->board->det_pin) {
+		ret = request_irq(host->board->det_pin, at91_mmc_det_irq,
+				SA_SAMPLE_RANDOM, DRIVER_NAME, host);
+		if (ret)
+			DBG("couldn't allocate MMC detect irq\n");
+	}
+
+	DBG(KERN_INFO "Added MCI driver\n");
+
+	return 0;
+}
+
+/*
+ * Remove a device
+ */
+static int at91_mci_remove(struct platform_device *pdev)
+{
+	struct mmc_host *mmc = platform_get_drvdata(pdev);
+	struct at91mci_host *host;
+
+	if (!mmc)
+		return -1;
+
+	host = mmc_priv(mmc);
+
+	if (host->present != -1) {
+		free_irq(host->board->det_pin, host);
+		cancel_delayed_work(&host->mmc->detect);
+	}
+
+	mmc_remove_host(mmc);
+	at91_mci_disable();
+	free_irq(AT91_ID_MCI, host);
+	mmc_free_host(mmc);
+
+	clk_disable(mci_clk);				/* Disable the peripheral clock */
+	clk_put(mci_clk);
+
+	platform_set_drvdata(pdev, NULL);
+
+	DBG("Removed\n");
+
+	return 0;
+}
+
+#ifdef CONFIG_PM
+static int at91_mci_suspend(struct platform_device *pdev, pm_message_t state)
+{
+	struct mmc_host *mmc = platform_get_drvdata(pdev);
+	int ret = 0;
+
+	if (mmc)
+		ret = mmc_suspend_host(mmc, state);
+
+	return ret;
+}
+
+static int at91_mci_resume(struct platform_device *pdev)
+{
+	struct mmc_host *mmc = platform_get_drvdata(pdev);
+	int ret = 0;
+
+	if (mmc)
+		ret = mmc_resume_host(mmc);
+
+	return ret;
+}
+#else
+#define at91_mci_suspend	NULL
+#define at91_mci_resume		NULL
+#endif
+
+static struct platform_driver at91_mci_driver = {
+	.probe		= at91_mci_probe,
+	.remove		= at91_mci_remove,
+	.suspend	= at91_mci_suspend,
+	.resume		= at91_mci_resume,
+	.driver		= {
+		.name	= DRIVER_NAME,
+		.owner	= THIS_MODULE,
+	},
+};
+
+static int __init at91_mci_init(void)
+{
+	return platform_driver_register(&at91_mci_driver);
+}
+
+static void __exit at91_mci_exit(void)
+{
+	platform_driver_unregister(&at91_mci_driver);
+}
+
+module_init(at91_mci_init);
+module_exit(at91_mci_exit);
+
+MODULE_DESCRIPTION("AT91 Multimedia Card Interface driver");
+MODULE_AUTHOR("Nick Randell");
+MODULE_LICENSE("GPL");