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: Marc St-Jean <Marc_St-Jean@pmc-sierra.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>

1 files changed, 653 insertions, 0 deletions

diff --git a/drivers/i2c/busses/i2c-pmcmsp.c b/drivers/i2c/busses/i2c-pmcmsp.c
new file mode 100644
index 000000000000..03188d277af1
--- /dev/null
+++ b/drivers/i2c/busses/i2c-pmcmsp.c
@@ -0,0 +1,653 @@
+/*
+ * 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);