i2c: New PMC MSP71xx TWI bus driver

Add TWI driver for the PMC-Sierra MSP71xx devices.

[JD: Drop the probe hack, don't set algo_data as we never use it, return
the right error code if the driver registration fails.]
Signed-off-by: NMarc St-Jean <Marc_St-Jean@pmc-sierra.com>
Signed-off-by: NJean Delvare <khali@linux-fr.org>

drivers/i2c/busses/Kconfig

@@ -652,4 +652,13 @@ config I2C_PNX
 	  This driver can also be built as a module.  If so, the module
 	  will be called i2c-pnx.
 
+config I2C_PMCMSP
+	tristate "PMC MSP I2C TWI Controller"
+	depends on PMC_MSP
+	help
+	  This driver supports the PMC TWI controller on MSP devices.
+
+	  This driver can also be built as module. If so, the module
+	  will be called i2c-pmcmsp.
+
 endmenu

drivers/i2c/busses/Makefile

@@ -32,6 +32,7 @@ obj-$(CONFIG_I2C_PARPORT_LIGHT)	+= i2c-parport-light.o
 obj-$(CONFIG_I2C_PASEMI)	+= i2c-pasemi.o
 obj-$(CONFIG_I2C_PCA_ISA)	+= i2c-pca-isa.o
 obj-$(CONFIG_I2C_PIIX4)		+= i2c-piix4.o
+obj-$(CONFIG_I2C_PMCMSP)	+= i2c-pmcmsp.o
 obj-$(CONFIG_I2C_PNX)		+= i2c-pnx.o
 obj-$(CONFIG_I2C_PROSAVAGE)	+= i2c-prosavage.o
 obj-$(CONFIG_I2C_PXA)		+= i2c-pxa.o

drivers/i2c/busses/i2c-pmcmsp.c

+/*
+ * Specific bus support for PMC-TWI compliant implementation on MSP71xx.
+ *
+ * Copyright 2005-2007 PMC-Sierra, Inc.
+ *
+ *  This program is free software; you can redistribute  it and/or modify it
+ *  under  the terms of  the GNU General  Public License as published by the
+ *  Free Software Foundation;  either version 2 of the  License, or (at your
+ *  option) any later version.
+ *
+ *  THIS  SOFTWARE  IS PROVIDED   ``AS  IS'' AND   ANY  EXPRESS OR IMPLIED
+ *  WARRANTIES,   INCLUDING, BUT NOT  LIMITED  TO, THE IMPLIED WARRANTIES OF
+ *  MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN
+ *  NO  EVENT  SHALL   THE AUTHOR  BE    LIABLE FOR ANY   DIRECT, INDIRECT,
+ *  INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ *  NOT LIMITED   TO, PROCUREMENT OF  SUBSTITUTE GOODS  OR SERVICES; LOSS OF
+ *  USE, DATA,  OR PROFITS; OR  BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
+ *  ANY THEORY OF LIABILITY, WHETHER IN  CONTRACT, STRICT LIABILITY, OR TORT
+ *  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ *  THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ *  You should have received a copy of the  GNU General Public License along
+ *  with this program; if not, write  to the Free Software Foundation, Inc.,
+ *  675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/platform_device.h>
+#include <linux/i2c.h>
+#include <linux/interrupt.h>
+#include <linux/completion.h>
+#include <linux/mutex.h>
+#include <linux/delay.h>
+#include <asm/io.h>
+
+#define DRV_NAME	"pmcmsptwi"
+
+#define MSP_TWI_SF_CLK_REG_OFFSET	0x00
+#define MSP_TWI_HS_CLK_REG_OFFSET	0x04
+#define MSP_TWI_CFG_REG_OFFSET		0x08
+#define MSP_TWI_CMD_REG_OFFSET		0x0c
+#define MSP_TWI_ADD_REG_OFFSET		0x10
+#define MSP_TWI_DAT_0_REG_OFFSET	0x14
+#define MSP_TWI_DAT_1_REG_OFFSET	0x18
+#define MSP_TWI_INT_STS_REG_OFFSET	0x1c
+#define MSP_TWI_INT_MSK_REG_OFFSET	0x20
+#define MSP_TWI_BUSY_REG_OFFSET		0x24
+
+#define MSP_TWI_INT_STS_DONE			(1 << 0)
+#define MSP_TWI_INT_STS_LOST_ARBITRATION	(1 << 1)
+#define MSP_TWI_INT_STS_NO_RESPONSE		(1 << 2)
+#define MSP_TWI_INT_STS_DATA_COLLISION		(1 << 3)
+#define MSP_TWI_INT_STS_BUSY			(1 << 4)
+#define MSP_TWI_INT_STS_ALL			0x1f
+
+#define MSP_MAX_BYTES_PER_RW		8
+#define MSP_MAX_POLL			5
+#define MSP_POLL_DELAY			10
+#define MSP_IRQ_TIMEOUT			(MSP_MAX_POLL * MSP_POLL_DELAY)
+
+/* IO Operation macros */
+#define pmcmsptwi_readl		__raw_readl
+#define pmcmsptwi_writel	__raw_writel
+
+/* TWI command type */
+enum pmcmsptwi_cmd_type {
+	MSP_TWI_CMD_WRITE	= 0,	/* Write only */
+	MSP_TWI_CMD_READ	= 1,	/* Read only */
+	MSP_TWI_CMD_WRITE_READ	= 2,	/* Write then Read */
+};
+
+/* The possible results of the xferCmd */
+enum pmcmsptwi_xfer_result {
+	MSP_TWI_XFER_OK	= 0,
+	MSP_TWI_XFER_TIMEOUT,
+	MSP_TWI_XFER_BUSY,
+	MSP_TWI_XFER_DATA_COLLISION,
+	MSP_TWI_XFER_NO_RESPONSE,
+	MSP_TWI_XFER_LOST_ARBITRATION,
+};
+
+/* Corresponds to a PMCTWI clock configuration register */
+struct pmcmsptwi_clock {
+	u8 filter;	/* Bits 15:12,	default = 0x03 */
+	u16 clock;	/* Bits 9:0,	default = 0x001f */
+};
+
+struct pmcmsptwi_clockcfg {
+	struct pmcmsptwi_clock standard;  /* The standard/fast clock config */
+	struct pmcmsptwi_clock highspeed; /* The highspeed clock config */
+};
+
+/* Corresponds to the main TWI configuration register */
+struct pmcmsptwi_cfg {
+	u8 arbf;	/* Bits 15:12,	default=0x03 */
+	u8 nak;		/* Bits 11:8,	default=0x03 */
+	u8 add10;	/* Bit 7,	default=0x00 */
+	u8 mst_code;	/* Bits 6:4,	default=0x00 */
+	u8 arb;		/* Bit 1,	default=0x01 */
+	u8 highspeed;	/* Bit 0,	default=0x00 */
+};
+
+/* A single pmctwi command to issue */
+struct pmcmsptwi_cmd {
+	u16 addr;	/* The slave address (7 or 10 bits) */
+	enum pmcmsptwi_cmd_type type;	/* The command type */
+	u8 write_len;	/* Number of bytes in the write buffer */
+	u8 read_len;	/* Number of bytes in the read buffer */
+	u8 *write_data;	/* Buffer of characters to send */
+	u8 *read_data;	/* Buffer to fill with incoming data */
+};
+
+/* The private data */
+struct pmcmsptwi_data {
+	void __iomem *iobase;			/* iomapped base for IO */
+	int irq;				/* IRQ to use (0 disables) */
+	struct completion wait;			/* Completion for xfer */
+	struct mutex lock;			/* Used for threadsafeness */
+	enum pmcmsptwi_xfer_result last_result;	/* result of last xfer */
+};
+
+/* The default settings */
+const static struct pmcmsptwi_clockcfg pmcmsptwi_defclockcfg = {
+	.standard = {
+		.filter	= 0x3,
+		.clock	= 0x1f,
+	},
+	.highspeed = {
+		.filter	= 0x3,
+		.clock	= 0x1f,
+	},
+};
+
+const static struct pmcmsptwi_cfg pmcmsptwi_defcfg = {
+	.arbf		= 0x03,
+	.nak		= 0x03,
+	.add10		= 0x00,
+	.mst_code	= 0x00,
+	.arb		= 0x01,
+	.highspeed	= 0x00,
+};
+
+static struct pmcmsptwi_data pmcmsptwi_data;
+
+static struct i2c_adapter pmcmsptwi_adapter;
+
+/* inline helper functions */
+static inline u32 pmcmsptwi_clock_to_reg(
+			const struct pmcmsptwi_clock *clock)
+{
+	return ((clock->filter & 0xf) << 12) | (clock->clock & 0x03ff);
+}
+
+static inline void pmcmsptwi_reg_to_clock(
+			u32 reg, struct pmcmsptwi_clock *clock)
+{
+	clock->filter = (reg >> 12) & 0xf;
+	clock->clock = reg & 0x03ff;
+}
+
+static inline u32 pmcmsptwi_cfg_to_reg(const struct pmcmsptwi_cfg *cfg)
+{
+	return ((cfg->arbf & 0xf) << 12) |
+		((cfg->nak & 0xf) << 8) |
+		((cfg->add10 & 0x1) << 7) |
+		((cfg->mst_code & 0x7) << 4) |
+		((cfg->arb & 0x1) << 1) |
+		(cfg->highspeed & 0x1);
+}
+
+static inline void pmcmsptwi_reg_to_cfg(u32 reg, struct pmcmsptwi_cfg *cfg)
+{
+	cfg->arbf = (reg >> 12) & 0xf;
+	cfg->nak = (reg >> 8) & 0xf;
+	cfg->add10 = (reg >> 7) & 0x1;
+	cfg->mst_code = (reg >> 4) & 0x7;
+	cfg->arb = (reg >> 1) & 0x1;
+	cfg->highspeed = reg & 0x1;
+}
+
+/*
+ * Sets the current clock configuration
+ */
+static void pmcmsptwi_set_clock_config(const struct pmcmsptwi_clockcfg *cfg,
+					struct pmcmsptwi_data *data)
+{
+	mutex_lock(&data->lock);
+	pmcmsptwi_writel(pmcmsptwi_clock_to_reg(&cfg->standard),
+				data->iobase + MSP_TWI_SF_CLK_REG_OFFSET);
+	pmcmsptwi_writel(pmcmsptwi_clock_to_reg(&cfg->highspeed),
+				data->iobase + MSP_TWI_HS_CLK_REG_OFFSET);
+	mutex_unlock(&data->lock);
+}
+
+/*
+ * Gets the current TWI bus configuration
+ */
+static void pmcmsptwi_get_twi_config(struct pmcmsptwi_cfg *cfg,
+					struct pmcmsptwi_data *data)
+{
+	mutex_lock(&data->lock);
+	pmcmsptwi_reg_to_cfg(pmcmsptwi_readl(
+				data->iobase + MSP_TWI_CFG_REG_OFFSET), cfg);
+	mutex_unlock(&data->lock);
+}
+
+/*
+ * Sets the current TWI bus configuration
+ */
+static void pmcmsptwi_set_twi_config(const struct pmcmsptwi_cfg *cfg,
+					struct pmcmsptwi_data *data)
+{
+	mutex_lock(&data->lock);
+	pmcmsptwi_writel(pmcmsptwi_cfg_to_reg(cfg),
+				data->iobase + MSP_TWI_CFG_REG_OFFSET);
+	mutex_unlock(&data->lock);
+}
+
+/*
+ * Parses the 'int_sts' register and returns a well-defined error code
+ */
+static enum pmcmsptwi_xfer_result pmcmsptwi_get_result(u32 reg)
+{
+	if (reg & MSP_TWI_INT_STS_LOST_ARBITRATION) {
+		dev_dbg(&pmcmsptwi_adapter.dev,
+			"Result: Lost arbitration\n");
+		return MSP_TWI_XFER_LOST_ARBITRATION;
+	} else if (reg & MSP_TWI_INT_STS_NO_RESPONSE) {
+		dev_dbg(&pmcmsptwi_adapter.dev,
+			"Result: No response\n");
+		return MSP_TWI_XFER_NO_RESPONSE;
+	} else if (reg & MSP_TWI_INT_STS_DATA_COLLISION) {
+		dev_dbg(&pmcmsptwi_adapter.dev,
+			"Result: Data collision\n");
+		return MSP_TWI_XFER_DATA_COLLISION;
+	} else if (reg & MSP_TWI_INT_STS_BUSY) {
+		dev_dbg(&pmcmsptwi_adapter.dev,
+			"Result: Bus busy\n");
+		return MSP_TWI_XFER_BUSY;
+	}
+
+	dev_dbg(&pmcmsptwi_adapter.dev, "Result: Operation succeeded\n");
+	return MSP_TWI_XFER_OK;
+}
+
+/*
+ * In interrupt mode, handle the interrupt.
+ * NOTE: Assumes data->lock is held.
+ */
+static irqreturn_t pmcmsptwi_interrupt(int irq, void *ptr)
+{
+	struct pmcmsptwi_data *data = ptr;
+
+	u32 reason = pmcmsptwi_readl(data->iobase +
+					MSP_TWI_INT_STS_REG_OFFSET);
+	pmcmsptwi_writel(reason, data->iobase + MSP_TWI_INT_STS_REG_OFFSET);
+
+	dev_dbg(&pmcmsptwi_adapter.dev, "Got interrupt 0x%08x\n", reason);
+	if (!(reason & MSP_TWI_INT_STS_DONE))
+		return IRQ_NONE;
+
+	data->last_result = pmcmsptwi_get_result(reason);
+	complete(&data->wait);
+
+	return IRQ_HANDLED;
+}
+
+/*
+ * Probe for and register the device and return 0 if there is one.
+ */
+static int __devinit pmcmsptwi_probe(struct platform_device *pldev)
+{
+	struct resource *res;
+	int rc = -ENODEV;
+
+	/* get the static platform resources */
+	res = platform_get_resource(pldev, IORESOURCE_MEM, 0);
+	if (!res) {
+		dev_err(&pldev->dev, "IOMEM resource not found\n");
+		goto ret_err;
+	}
+
+	/* reserve the memory region */
+	if (!request_mem_region(res->start, res->end - res->start + 1,
+				pldev->name)) {
+		dev_err(&pldev->dev,
+			"Unable to get memory/io address region 0x%08x\n",
+			res->start);
+		rc = -EBUSY;
+		goto ret_err;
+	}
+
+	/* remap the memory */
+	pmcmsptwi_data.iobase = ioremap_nocache(res->start,
+						res->end - res->start + 1);
+	if (!pmcmsptwi_data.iobase) {
+		dev_err(&pldev->dev,
+			"Unable to ioremap address 0x%08x\n", res->start);
+		rc = -EIO;
+		goto ret_unreserve;
+	}
+
+	/* request the irq */
+	pmcmsptwi_data.irq = platform_get_irq(pldev, 0);
+	if (pmcmsptwi_data.irq) {
+		rc = request_irq(pmcmsptwi_data.irq, &pmcmsptwi_interrupt,
+			IRQF_SHARED | IRQF_DISABLED | IRQF_SAMPLE_RANDOM,
+			pldev->name, &pmcmsptwi_data);
+		if (rc == 0) {
+			/*
+			 * Enable 'DONE' interrupt only.
+			 *
+			 * If you enable all interrupts, you will get one on
+			 * error and another when the operation completes.
+			 * This way you only have to handle one interrupt,
+			 * but you can still check all result flags.
+			 */
+			pmcmsptwi_writel(MSP_TWI_INT_STS_DONE,
+					pmcmsptwi_data.iobase +
+					MSP_TWI_INT_MSK_REG_OFFSET);
+		} else {
+			dev_warn(&pldev->dev,
+				"Could not assign TWI IRQ handler "
+				"to irq %d (continuing with poll)\n",
+				pmcmsptwi_data.irq);
+			pmcmsptwi_data.irq = 0;
+		}
+	}
+
+	init_completion(&pmcmsptwi_data.wait);
+	mutex_init(&pmcmsptwi_data.lock);
+
+	pmcmsptwi_set_clock_config(&pmcmsptwi_defclockcfg, &pmcmsptwi_data);
+	pmcmsptwi_set_twi_config(&pmcmsptwi_defcfg, &pmcmsptwi_data);
+
+	printk(KERN_INFO DRV_NAME ": Registering MSP71xx I2C adapter\n");
+
+	pmcmsptwi_adapter.dev.parent = &pldev->dev;
+	platform_set_drvdata(pldev, &pmcmsptwi_adapter);
+	i2c_set_adapdata(&pmcmsptwi_adapter, &pmcmsptwi_data);
+
+	rc = i2c_add_adapter(&pmcmsptwi_adapter);
+	if (rc) {
+		dev_err(&pldev->dev, "Unable to register I2C adapter\n");
+		goto ret_unmap;
+	}
+
+	return 0;
+
+ret_unmap:
+	platform_set_drvdata(pldev, NULL);
+	if (pmcmsptwi_data.irq) {
+		pmcmsptwi_writel(0,
+			pmcmsptwi_data.iobase + MSP_TWI_INT_MSK_REG_OFFSET);
+		free_irq(pmcmsptwi_data.irq, &pmcmsptwi_data);
+	}
+
+	iounmap(pmcmsptwi_data.iobase);
+
+ret_unreserve:
+	release_mem_region(res->start, res->end - res->start + 1);
+
+ret_err:
+	return rc;
+}
+
+/*
+ * Release the device and return 0 if there is one.
+ */
+static int __devexit pmcmsptwi_remove(struct platform_device *pldev)
+{
+	struct resource *res;
+
+	i2c_del_adapter(&pmcmsptwi_adapter);
+
+	platform_set_drvdata(pldev, NULL);
+	if (pmcmsptwi_data.irq) {
+		pmcmsptwi_writel(0,
+			pmcmsptwi_data.iobase + MSP_TWI_INT_MSK_REG_OFFSET);
+		free_irq(pmcmsptwi_data.irq, &pmcmsptwi_data);
+	}
+
+	iounmap(pmcmsptwi_data.iobase);
+
+	res = platform_get_resource(pldev, IORESOURCE_MEM, 0);
+	release_mem_region(res->start, res->end - res->start + 1);
+
+	return 0;
+}
+
+/*
+ * Polls the 'busy' register until the command is complete.
+ * NOTE: Assumes data->lock is held.
+ */
+static void pmcmsptwi_poll_complete(struct pmcmsptwi_data *data)
+{
+	int i;
+
+	for (i = 0; i < MSP_MAX_POLL; i++) {
+		u32 val = pmcmsptwi_readl(data->iobase +
+						MSP_TWI_BUSY_REG_OFFSET);
+		if (val == 0) {
+			u32 reason = pmcmsptwi_readl(data->iobase +
+						MSP_TWI_INT_STS_REG_OFFSET);
+			pmcmsptwi_writel(reason, data->iobase +
+						MSP_TWI_INT_STS_REG_OFFSET);
+			data->last_result = pmcmsptwi_get_result(reason);
+			return;
+		}
+		udelay(MSP_POLL_DELAY);
+	}
+
+	dev_dbg(&pmcmsptwi_adapter.dev, "Result: Poll timeout\n");
+	data->last_result = MSP_TWI_XFER_TIMEOUT;
+}
+
+/*
+ * Do the transfer (low level):
+ *   May use interrupt-driven or polling, depending on if an IRQ is
+ *   presently registered.
+ * NOTE: Assumes data->lock is held.
+ */
+static enum pmcmsptwi_xfer_result pmcmsptwi_do_xfer(
+			u32 reg, struct pmcmsptwi_data *data)
+{
+	dev_dbg(&pmcmsptwi_adapter.dev, "Writing cmd reg 0x%08x\n", reg);
+	pmcmsptwi_writel(reg, data->iobase + MSP_TWI_CMD_REG_OFFSET);
+	if (data->irq) {
+		unsigned long timeleft = wait_for_completion_timeout(
+						&data->wait, MSP_IRQ_TIMEOUT);
+		if (timeleft == 0) {
+			dev_dbg(&pmcmsptwi_adapter.dev,
+				"Result: IRQ timeout\n");
+			complete(&data->wait);
+			data->last_result = MSP_TWI_XFER_TIMEOUT;
+		}
+	} else
+		pmcmsptwi_poll_complete(data);
+
+	return data->last_result;
+}
+
+/*
+ * Helper routine, converts 'pmctwi_cmd' struct to register format
+ */
+static inline u32 pmcmsptwi_cmd_to_reg(const struct pmcmsptwi_cmd *cmd)
+{
+	return ((cmd->type & 0x3) << 8) |
+		(((cmd->write_len - 1) & 0x7) << 4) |
+		((cmd->read_len - 1) & 0x7);
+}
+
+/*
+ * Do the transfer (high level)
+ */
+static enum pmcmsptwi_xfer_result pmcmsptwi_xfer_cmd(
+			struct pmcmsptwi_cmd *cmd,
+			struct pmcmsptwi_data *data)
+{
+	enum pmcmsptwi_xfer_result retval;
+
+	if ((cmd->type == MSP_TWI_CMD_WRITE && cmd->write_len == 0) ||
+	    (cmd->type == MSP_TWI_CMD_READ && cmd->read_len == 0) ||
+	    (cmd->type == MSP_TWI_CMD_WRITE_READ &&
+	    (cmd->read_len == 0 || cmd->write_len == 0))) {
+		dev_err(&pmcmsptwi_adapter.dev,
+			"%s: Cannot transfer less than 1 byte\n",
+			__FUNCTION__);
+		return -EINVAL;
+	}
+
+	if (cmd->read_len > MSP_MAX_BYTES_PER_RW ||
+	    cmd->write_len > MSP_MAX_BYTES_PER_RW) {
+		dev_err(&pmcmsptwi_adapter.dev,
+			"%s: Cannot transfer more than %d bytes\n",
+			__FUNCTION__, MSP_MAX_BYTES_PER_RW);
+		return -EINVAL;
+	}
+
+	mutex_lock(&data->lock);
+	dev_dbg(&pmcmsptwi_adapter.dev,
+		"Setting address to 0x%04x\n", cmd->addr);
+	pmcmsptwi_writel(cmd->addr, data->iobase + MSP_TWI_ADD_REG_OFFSET);
+
+	if (cmd->type == MSP_TWI_CMD_WRITE ||
+	    cmd->type == MSP_TWI_CMD_WRITE_READ) {
+		__be64 tmp = cpu_to_be64p((u64 *)cmd->write_data);
+		tmp >>= (MSP_MAX_BYTES_PER_RW - cmd->write_len) * 8;
+		dev_dbg(&pmcmsptwi_adapter.dev, "Writing 0x%016llx\n", tmp);
+		pmcmsptwi_writel(tmp & 0x00000000ffffffffLL,
+				data->iobase + MSP_TWI_DAT_0_REG_OFFSET);
+		if (cmd->write_len > 4)
+			pmcmsptwi_writel(tmp >> 32,
+				data->iobase + MSP_TWI_DAT_1_REG_OFFSET);
+	}
+
+	retval = pmcmsptwi_do_xfer(pmcmsptwi_cmd_to_reg(cmd), data);
+	if (retval != MSP_TWI_XFER_OK)
+		goto xfer_err;
+
+	if (cmd->type == MSP_TWI_CMD_READ ||
+	    cmd->type == MSP_TWI_CMD_WRITE_READ) {
+		int i;
+		u64 rmsk = ~(0xffffffffffffffffLL << (cmd->read_len * 8));
+		u64 tmp = (u64)pmcmsptwi_readl(data->iobase +
+					MSP_TWI_DAT_0_REG_OFFSET);
+		if (cmd->read_len > 4)
+			tmp |= (u64)pmcmsptwi_readl(data->iobase +
+					MSP_TWI_DAT_1_REG_OFFSET) << 32;
+		tmp &= rmsk;
+		dev_dbg(&pmcmsptwi_adapter.dev, "Read 0x%016llx\n", tmp);
+
+		for (i = 0; i < cmd->read_len; i++)
+			cmd->read_data[i] = tmp >> i;
+	}
+
+xfer_err:
+	mutex_unlock(&data->lock);
+
+	return retval;
+}
+
+/* -- Algorithm functions -- */
+
+/*
+ * Sends an i2c command out on the adapter
+ */
+static int pmcmsptwi_master_xfer(struct i2c_adapter *adap,
+				struct i2c_msg *msg, int num)
+{
+	struct pmcmsptwi_data *data = i2c_get_adapdata(adap);
+	struct pmcmsptwi_cmd cmd;
+	struct pmcmsptwi_cfg oldcfg, newcfg;
+	int ret;
+
+	if (num > 2) {
+		dev_dbg(&adap->dev, "%d messages unsupported\n", num);
+		return -EINVAL;
+	} else if (num == 2) {
+		/* Check for a dual write-then-read command */
+		struct i2c_msg *nextmsg = msg + 1;
+		if (!(msg->flags & I2C_M_RD) &&
+		    (nextmsg->flags & I2C_M_RD) &&
+		    msg->addr == nextmsg->addr) {
+			cmd.type = MSP_TWI_CMD_WRITE_READ;
+			cmd.write_len = msg->len;
+			cmd.write_data = msg->buf;
+			cmd.read_len = nextmsg->len;
+			cmd.read_data = nextmsg->buf;
+		} else {
+			dev_dbg(&adap->dev,
+				"Non write-read dual messages unsupported\n");
+			return -EINVAL;
+		}
+	} else if (msg->flags & I2C_M_RD) {
+		cmd.type = MSP_TWI_CMD_READ;
+		cmd.read_len = msg->len;
+		cmd.read_data = msg->buf;
+		cmd.write_len = 0;
+		cmd.write_data = NULL;
+	} else {
+		cmd.type = MSP_TWI_CMD_WRITE;
+		cmd.read_len = 0;
+		cmd.read_data = NULL;
+		cmd.write_len = msg->len;
+		cmd.write_data = msg->buf;
+	}
+
+	if (msg->len == 0) {
+		dev_err(&adap->dev, "Zero-byte messages unsupported\n");
+		return -EINVAL;
+	}
+
+	cmd.addr = msg->addr;
+
+	if (msg->flags & I2C_M_TEN) {
+		pmcmsptwi_get_twi_config(&newcfg, data);
+		memcpy(&oldcfg, &newcfg, sizeof(oldcfg));
+
+		/* Set the special 10-bit address flag */
+		newcfg.add10 = 1;
+
+		pmcmsptwi_set_twi_config(&newcfg, data);
+	}
+
+	/* Execute the command */
+	ret = pmcmsptwi_xfer_cmd(&cmd, data);
+
+	if (msg->flags & I2C_M_TEN)
+		pmcmsptwi_set_twi_config(&oldcfg, data);
+
+	dev_dbg(&adap->dev, "I2C %s of %d bytes ",
+		(msg->flags & I2C_M_RD) ? "read" : "write", msg->len);
+	if (ret != MSP_TWI_XFER_OK) {
+		/*
+		 * TODO: We could potentially loop and retry in the case
+		 * of MSP_TWI_XFER_TIMEOUT.
+		 */
+		dev_dbg(&adap->dev, "failed\n");
+		return -1;
+	}
+
+	dev_dbg(&adap->dev, "succeeded\n");
+	return 0;
+}
+
+static u32 pmcmsptwi_i2c_func(struct i2c_adapter *adapter)
+{
+	return I2C_FUNC_I2C | I2C_FUNC_10BIT_ADDR |
+		I2C_FUNC_SMBUS_BYTE | I2C_FUNC_SMBUS_BYTE_DATA |
+		I2C_FUNC_SMBUS_WORD_DATA | I2C_FUNC_SMBUS_PROC_CALL;
+}
+
+/* -- Initialization -- */
+
+static struct i2c_algorithm pmcmsptwi_algo = {
+	.master_xfer	= pmcmsptwi_master_xfer,
+	.functionality	= pmcmsptwi_i2c_func,
+};
+
+static struct i2c_adapter pmcmsptwi_adapter = {
+	.owner		= THIS_MODULE,
+	.class		= I2C_CLASS_HWMON,
+	.algo		= &pmcmsptwi_algo,
+	.name		= DRV_NAME,
+};
+
+static struct platform_driver pmcmsptwi_driver = {
+	.probe  = pmcmsptwi_probe,
+	.remove	= __devexit_p(pmcmsptwi_remove),
+	.driver {
+		.name	= DRV_NAME,
+		.owner	= THIS_MODULE,
+	},
+};
+
+static int __init pmcmsptwi_init(void)
+{
+	return platform_driver_register(&pmcmsptwi_driver);
+}
+
+static void __exit pmcmsptwi_exit(void)
+{
+	platform_driver_unregister(&pmcmsptwi_driver);
+}
+
+MODULE_DESCRIPTION("PMC MSP TWI/SMBus/I2C driver");
+MODULE_LICENSE("GPL");
+
+module_init(pmcmsptwi_init);
+module_exit(pmcmsptwi_exit);