linux/drivers/i2c/busses/i2c-pmcmsp.c
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   1/*
   2 * Specific bus support for PMC-TWI compliant implementation on MSP71xx.
   3 *
   4 * Copyright 2005-2007 PMC-Sierra, Inc.
   5 *
   6 *  This program is free software; you can redistribute  it and/or modify it
   7 *  under  the terms of  the GNU General  Public License as published by the
   8 *  Free Software Foundation;  either version 2 of the  License, or (at your
   9 *  option) any later version.
  10 *
  11 *  THIS  SOFTWARE  IS PROVIDED   ``AS  IS'' AND   ANY  EXPRESS OR IMPLIED
  12 *  WARRANTIES,   INCLUDING, BUT NOT  LIMITED  TO, THE IMPLIED WARRANTIES OF
  13 *  MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN
  14 *  NO  EVENT  SHALL   THE AUTHOR  BE    LIABLE FOR ANY   DIRECT, INDIRECT,
  15 *  INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  16 *  NOT LIMITED   TO, PROCUREMENT OF  SUBSTITUTE GOODS  OR SERVICES; LOSS OF
  17 *  USE, DATA,  OR PROFITS; OR  BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
  18 *  ANY THEORY OF LIABILITY, WHETHER IN  CONTRACT, STRICT LIABILITY, OR TORT
  19 *  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  20 *  THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  21 *
  22 *  You should have received a copy of the  GNU General Public License along
  23 *  with this program; if not, write  to the Free Software Foundation, Inc.,
  24 *  675 Mass Ave, Cambridge, MA 02139, USA.
  25 */
  26
  27#include <linux/kernel.h>
  28#include <linux/module.h>
  29#include <linux/init.h>
  30#include <linux/platform_device.h>
  31#include <linux/i2c.h>
  32#include <linux/interrupt.h>
  33#include <linux/completion.h>
  34#include <linux/mutex.h>
  35#include <linux/delay.h>
  36#include <asm/io.h>
  37
  38#define DRV_NAME        "pmcmsptwi"
  39
  40#define MSP_TWI_SF_CLK_REG_OFFSET       0x00
  41#define MSP_TWI_HS_CLK_REG_OFFSET       0x04
  42#define MSP_TWI_CFG_REG_OFFSET          0x08
  43#define MSP_TWI_CMD_REG_OFFSET          0x0c
  44#define MSP_TWI_ADD_REG_OFFSET          0x10
  45#define MSP_TWI_DAT_0_REG_OFFSET        0x14
  46#define MSP_TWI_DAT_1_REG_OFFSET        0x18
  47#define MSP_TWI_INT_STS_REG_OFFSET      0x1c
  48#define MSP_TWI_INT_MSK_REG_OFFSET      0x20
  49#define MSP_TWI_BUSY_REG_OFFSET         0x24
  50
  51#define MSP_TWI_INT_STS_DONE                    (1 << 0)
  52#define MSP_TWI_INT_STS_LOST_ARBITRATION        (1 << 1)
  53#define MSP_TWI_INT_STS_NO_RESPONSE             (1 << 2)
  54#define MSP_TWI_INT_STS_DATA_COLLISION          (1 << 3)
  55#define MSP_TWI_INT_STS_BUSY                    (1 << 4)
  56#define MSP_TWI_INT_STS_ALL                     0x1f
  57
  58#define MSP_MAX_BYTES_PER_RW            8
  59#define MSP_MAX_POLL                    5
  60#define MSP_POLL_DELAY                  10
  61#define MSP_IRQ_TIMEOUT                 (MSP_MAX_POLL * MSP_POLL_DELAY)
  62
  63/* IO Operation macros */
  64#define pmcmsptwi_readl         __raw_readl
  65#define pmcmsptwi_writel        __raw_writel
  66
  67/* TWI command type */
  68enum pmcmsptwi_cmd_type {
  69        MSP_TWI_CMD_WRITE       = 0,    /* Write only */
  70        MSP_TWI_CMD_READ        = 1,    /* Read only */
  71        MSP_TWI_CMD_WRITE_READ  = 2,    /* Write then Read */
  72};
  73
  74/* The possible results of the xferCmd */
  75enum pmcmsptwi_xfer_result {
  76        MSP_TWI_XFER_OK = 0,
  77        MSP_TWI_XFER_TIMEOUT,
  78        MSP_TWI_XFER_BUSY,
  79        MSP_TWI_XFER_DATA_COLLISION,
  80        MSP_TWI_XFER_NO_RESPONSE,
  81        MSP_TWI_XFER_LOST_ARBITRATION,
  82};
  83
  84/* Corresponds to a PMCTWI clock configuration register */
  85struct pmcmsptwi_clock {
  86        u8 filter;      /* Bits 15:12,  default = 0x03 */
  87        u16 clock;      /* Bits 9:0,    default = 0x001f */
  88};
  89
  90struct pmcmsptwi_clockcfg {
  91        struct pmcmsptwi_clock standard;  /* The standard/fast clock config */
  92        struct pmcmsptwi_clock highspeed; /* The highspeed clock config */
  93};
  94
  95/* Corresponds to the main TWI configuration register */
  96struct pmcmsptwi_cfg {
  97        u8 arbf;        /* Bits 15:12,  default=0x03 */
  98        u8 nak;         /* Bits 11:8,   default=0x03 */
  99        u8 add10;       /* Bit 7,       default=0x00 */
 100        u8 mst_code;    /* Bits 6:4,    default=0x00 */
 101        u8 arb;         /* Bit 1,       default=0x01 */
 102        u8 highspeed;   /* Bit 0,       default=0x00 */
 103};
 104
 105/* A single pmctwi command to issue */
 106struct pmcmsptwi_cmd {
 107        u16 addr;       /* The slave address (7 or 10 bits) */
 108        enum pmcmsptwi_cmd_type type;   /* The command type */
 109        u8 write_len;   /* Number of bytes in the write buffer */
 110        u8 read_len;    /* Number of bytes in the read buffer */
 111        u8 *write_data; /* Buffer of characters to send */
 112        u8 *read_data;  /* Buffer to fill with incoming data */
 113};
 114
 115/* The private data */
 116struct pmcmsptwi_data {
 117        void __iomem *iobase;                   /* iomapped base for IO */
 118        int irq;                                /* IRQ to use (0 disables) */
 119        struct completion wait;                 /* Completion for xfer */
 120        struct mutex lock;                      /* Used for threadsafeness */
 121        enum pmcmsptwi_xfer_result last_result; /* result of last xfer */
 122};
 123
 124/* The default settings */
 125static const struct pmcmsptwi_clockcfg pmcmsptwi_defclockcfg = {
 126        .standard = {
 127                .filter = 0x3,
 128                .clock  = 0x1f,
 129        },
 130        .highspeed = {
 131                .filter = 0x3,
 132                .clock  = 0x1f,
 133        },
 134};
 135
 136static const struct pmcmsptwi_cfg pmcmsptwi_defcfg = {
 137        .arbf           = 0x03,
 138        .nak            = 0x03,
 139        .add10          = 0x00,
 140        .mst_code       = 0x00,
 141        .arb            = 0x01,
 142        .highspeed      = 0x00,
 143};
 144
 145static struct pmcmsptwi_data pmcmsptwi_data;
 146
 147static struct i2c_adapter pmcmsptwi_adapter;
 148
 149/* inline helper functions */
 150static inline u32 pmcmsptwi_clock_to_reg(
 151                        const struct pmcmsptwi_clock *clock)
 152{
 153        return ((clock->filter & 0xf) << 12) | (clock->clock & 0x03ff);
 154}
 155
 156static inline void pmcmsptwi_reg_to_clock(
 157                        u32 reg, struct pmcmsptwi_clock *clock)
 158{
 159        clock->filter = (reg >> 12) & 0xf;
 160        clock->clock = reg & 0x03ff;
 161}
 162
 163static inline u32 pmcmsptwi_cfg_to_reg(const struct pmcmsptwi_cfg *cfg)
 164{
 165        return ((cfg->arbf & 0xf) << 12) |
 166                ((cfg->nak & 0xf) << 8) |
 167                ((cfg->add10 & 0x1) << 7) |
 168                ((cfg->mst_code & 0x7) << 4) |
 169                ((cfg->arb & 0x1) << 1) |
 170                (cfg->highspeed & 0x1);
 171}
 172
 173static inline void pmcmsptwi_reg_to_cfg(u32 reg, struct pmcmsptwi_cfg *cfg)
 174{
 175        cfg->arbf = (reg >> 12) & 0xf;
 176        cfg->nak = (reg >> 8) & 0xf;
 177        cfg->add10 = (reg >> 7) & 0x1;
 178        cfg->mst_code = (reg >> 4) & 0x7;
 179        cfg->arb = (reg >> 1) & 0x1;
 180        cfg->highspeed = reg & 0x1;
 181}
 182
 183/*
 184 * Sets the current clock configuration
 185 */
 186static void pmcmsptwi_set_clock_config(const struct pmcmsptwi_clockcfg *cfg,
 187                                        struct pmcmsptwi_data *data)
 188{
 189        mutex_lock(&data->lock);
 190        pmcmsptwi_writel(pmcmsptwi_clock_to_reg(&cfg->standard),
 191                                data->iobase + MSP_TWI_SF_CLK_REG_OFFSET);
 192        pmcmsptwi_writel(pmcmsptwi_clock_to_reg(&cfg->highspeed),
 193                                data->iobase + MSP_TWI_HS_CLK_REG_OFFSET);
 194        mutex_unlock(&data->lock);
 195}
 196
 197/*
 198 * Gets the current TWI bus configuration
 199 */
 200static void pmcmsptwi_get_twi_config(struct pmcmsptwi_cfg *cfg,
 201                                        struct pmcmsptwi_data *data)
 202{
 203        mutex_lock(&data->lock);
 204        pmcmsptwi_reg_to_cfg(pmcmsptwi_readl(
 205                                data->iobase + MSP_TWI_CFG_REG_OFFSET), cfg);
 206        mutex_unlock(&data->lock);
 207}
 208
 209/*
 210 * Sets the current TWI bus configuration
 211 */
 212static void pmcmsptwi_set_twi_config(const struct pmcmsptwi_cfg *cfg,
 213                                        struct pmcmsptwi_data *data)
 214{
 215        mutex_lock(&data->lock);
 216        pmcmsptwi_writel(pmcmsptwi_cfg_to_reg(cfg),
 217                                data->iobase + MSP_TWI_CFG_REG_OFFSET);
 218        mutex_unlock(&data->lock);
 219}
 220
 221/*
 222 * Parses the 'int_sts' register and returns a well-defined error code
 223 */
 224static enum pmcmsptwi_xfer_result pmcmsptwi_get_result(u32 reg)
 225{
 226        if (reg & MSP_TWI_INT_STS_LOST_ARBITRATION) {
 227                dev_dbg(&pmcmsptwi_adapter.dev,
 228                        "Result: Lost arbitration\n");
 229                return MSP_TWI_XFER_LOST_ARBITRATION;
 230        } else if (reg & MSP_TWI_INT_STS_NO_RESPONSE) {
 231                dev_dbg(&pmcmsptwi_adapter.dev,
 232                        "Result: No response\n");
 233                return MSP_TWI_XFER_NO_RESPONSE;
 234        } else if (reg & MSP_TWI_INT_STS_DATA_COLLISION) {
 235                dev_dbg(&pmcmsptwi_adapter.dev,
 236                        "Result: Data collision\n");
 237                return MSP_TWI_XFER_DATA_COLLISION;
 238        } else if (reg & MSP_TWI_INT_STS_BUSY) {
 239                dev_dbg(&pmcmsptwi_adapter.dev,
 240                        "Result: Bus busy\n");
 241                return MSP_TWI_XFER_BUSY;
 242        }
 243
 244        dev_dbg(&pmcmsptwi_adapter.dev, "Result: Operation succeeded\n");
 245        return MSP_TWI_XFER_OK;
 246}
 247
 248/*
 249 * In interrupt mode, handle the interrupt.
 250 * NOTE: Assumes data->lock is held.
 251 */
 252static irqreturn_t pmcmsptwi_interrupt(int irq, void *ptr)
 253{
 254        struct pmcmsptwi_data *data = ptr;
 255
 256        u32 reason = pmcmsptwi_readl(data->iobase +
 257                                        MSP_TWI_INT_STS_REG_OFFSET);
 258        pmcmsptwi_writel(reason, data->iobase + MSP_TWI_INT_STS_REG_OFFSET);
 259
 260        dev_dbg(&pmcmsptwi_adapter.dev, "Got interrupt 0x%08x\n", reason);
 261        if (!(reason & MSP_TWI_INT_STS_DONE))
 262                return IRQ_NONE;
 263
 264        data->last_result = pmcmsptwi_get_result(reason);
 265        complete(&data->wait);
 266
 267        return IRQ_HANDLED;
 268}
 269
 270/*
 271 * Probe for and register the device and return 0 if there is one.
 272 */
 273static int __devinit pmcmsptwi_probe(struct platform_device *pldev)
 274{
 275        struct resource *res;
 276        int rc = -ENODEV;
 277
 278        /* get the static platform resources */
 279        res = platform_get_resource(pldev, IORESOURCE_MEM, 0);
 280        if (!res) {
 281                dev_err(&pldev->dev, "IOMEM resource not found\n");
 282                goto ret_err;
 283        }
 284
 285        /* reserve the memory region */
 286        if (!request_mem_region(res->start, resource_size(res),
 287                                pldev->name)) {
 288                dev_err(&pldev->dev,
 289                        "Unable to get memory/io address region 0x%08x\n",
 290                        res->start);
 291                rc = -EBUSY;
 292                goto ret_err;
 293        }
 294
 295        /* remap the memory */
 296        pmcmsptwi_data.iobase = ioremap_nocache(res->start,
 297                                                resource_size(res));
 298        if (!pmcmsptwi_data.iobase) {
 299                dev_err(&pldev->dev,
 300                        "Unable to ioremap address 0x%08x\n", res->start);
 301                rc = -EIO;
 302                goto ret_unreserve;
 303        }
 304
 305        /* request the irq */
 306        pmcmsptwi_data.irq = platform_get_irq(pldev, 0);
 307        if (pmcmsptwi_data.irq) {
 308                rc = request_irq(pmcmsptwi_data.irq, &pmcmsptwi_interrupt,
 309                        IRQF_SHARED | IRQF_DISABLED | IRQF_SAMPLE_RANDOM,
 310                        pldev->name, &pmcmsptwi_data);
 311                if (rc == 0) {
 312                        /*
 313                         * Enable 'DONE' interrupt only.
 314                         *
 315                         * If you enable all interrupts, you will get one on
 316                         * error and another when the operation completes.
 317                         * This way you only have to handle one interrupt,
 318                         * but you can still check all result flags.
 319                         */
 320                        pmcmsptwi_writel(MSP_TWI_INT_STS_DONE,
 321                                        pmcmsptwi_data.iobase +
 322                                        MSP_TWI_INT_MSK_REG_OFFSET);
 323                } else {
 324                        dev_warn(&pldev->dev,
 325                                "Could not assign TWI IRQ handler "
 326                                "to irq %d (continuing with poll)\n",
 327                                pmcmsptwi_data.irq);
 328                        pmcmsptwi_data.irq = 0;
 329                }
 330        }
 331
 332        init_completion(&pmcmsptwi_data.wait);
 333        mutex_init(&pmcmsptwi_data.lock);
 334
 335        pmcmsptwi_set_clock_config(&pmcmsptwi_defclockcfg, &pmcmsptwi_data);
 336        pmcmsptwi_set_twi_config(&pmcmsptwi_defcfg, &pmcmsptwi_data);
 337
 338        printk(KERN_INFO DRV_NAME ": Registering MSP71xx I2C adapter\n");
 339
 340        pmcmsptwi_adapter.dev.parent = &pldev->dev;
 341        platform_set_drvdata(pldev, &pmcmsptwi_adapter);
 342        i2c_set_adapdata(&pmcmsptwi_adapter, &pmcmsptwi_data);
 343
 344        rc = i2c_add_adapter(&pmcmsptwi_adapter);
 345        if (rc) {
 346                dev_err(&pldev->dev, "Unable to register I2C adapter\n");
 347                goto ret_unmap;
 348        }
 349
 350        return 0;
 351
 352ret_unmap:
 353        platform_set_drvdata(pldev, NULL);
 354        if (pmcmsptwi_data.irq) {
 355                pmcmsptwi_writel(0,
 356                        pmcmsptwi_data.iobase + MSP_TWI_INT_MSK_REG_OFFSET);
 357                free_irq(pmcmsptwi_data.irq, &pmcmsptwi_data);
 358        }
 359
 360        iounmap(pmcmsptwi_data.iobase);
 361
 362ret_unreserve:
 363        release_mem_region(res->start, resource_size(res));
 364
 365ret_err:
 366        return rc;
 367}
 368
 369/*
 370 * Release the device and return 0 if there is one.
 371 */
 372static int __devexit pmcmsptwi_remove(struct platform_device *pldev)
 373{
 374        struct resource *res;
 375
 376        i2c_del_adapter(&pmcmsptwi_adapter);
 377
 378        platform_set_drvdata(pldev, NULL);
 379        if (pmcmsptwi_data.irq) {
 380                pmcmsptwi_writel(0,
 381                        pmcmsptwi_data.iobase + MSP_TWI_INT_MSK_REG_OFFSET);
 382                free_irq(pmcmsptwi_data.irq, &pmcmsptwi_data);
 383        }
 384
 385        iounmap(pmcmsptwi_data.iobase);
 386
 387        res = platform_get_resource(pldev, IORESOURCE_MEM, 0);
 388        release_mem_region(res->start, resource_size(res));
 389
 390        return 0;
 391}
 392
 393/*
 394 * Polls the 'busy' register until the command is complete.
 395 * NOTE: Assumes data->lock is held.
 396 */
 397static void pmcmsptwi_poll_complete(struct pmcmsptwi_data *data)
 398{
 399        int i;
 400
 401        for (i = 0; i < MSP_MAX_POLL; i++) {
 402                u32 val = pmcmsptwi_readl(data->iobase +
 403                                                MSP_TWI_BUSY_REG_OFFSET);
 404                if (val == 0) {
 405                        u32 reason = pmcmsptwi_readl(data->iobase +
 406                                                MSP_TWI_INT_STS_REG_OFFSET);
 407                        pmcmsptwi_writel(reason, data->iobase +
 408                                                MSP_TWI_INT_STS_REG_OFFSET);
 409                        data->last_result = pmcmsptwi_get_result(reason);
 410                        return;
 411                }
 412                udelay(MSP_POLL_DELAY);
 413        }
 414
 415        dev_dbg(&pmcmsptwi_adapter.dev, "Result: Poll timeout\n");
 416        data->last_result = MSP_TWI_XFER_TIMEOUT;
 417}
 418
 419/*
 420 * Do the transfer (low level):
 421 *   May use interrupt-driven or polling, depending on if an IRQ is
 422 *   presently registered.
 423 * NOTE: Assumes data->lock is held.
 424 */
 425static enum pmcmsptwi_xfer_result pmcmsptwi_do_xfer(
 426                        u32 reg, struct pmcmsptwi_data *data)
 427{
 428        dev_dbg(&pmcmsptwi_adapter.dev, "Writing cmd reg 0x%08x\n", reg);
 429        pmcmsptwi_writel(reg, data->iobase + MSP_TWI_CMD_REG_OFFSET);
 430        if (data->irq) {
 431                unsigned long timeleft = wait_for_completion_timeout(
 432                                                &data->wait, MSP_IRQ_TIMEOUT);
 433                if (timeleft == 0) {
 434                        dev_dbg(&pmcmsptwi_adapter.dev,
 435                                "Result: IRQ timeout\n");
 436                        complete(&data->wait);
 437                        data->last_result = MSP_TWI_XFER_TIMEOUT;
 438                }
 439        } else
 440                pmcmsptwi_poll_complete(data);
 441
 442        return data->last_result;
 443}
 444
 445/*
 446 * Helper routine, converts 'pmctwi_cmd' struct to register format
 447 */
 448static inline u32 pmcmsptwi_cmd_to_reg(const struct pmcmsptwi_cmd *cmd)
 449{
 450        return ((cmd->type & 0x3) << 8) |
 451                (((cmd->write_len - 1) & 0x7) << 4) |
 452                ((cmd->read_len - 1) & 0x7);
 453}
 454
 455/*
 456 * Do the transfer (high level)
 457 */
 458static enum pmcmsptwi_xfer_result pmcmsptwi_xfer_cmd(
 459                        struct pmcmsptwi_cmd *cmd,
 460                        struct pmcmsptwi_data *data)
 461{
 462        enum pmcmsptwi_xfer_result retval;
 463
 464        if ((cmd->type == MSP_TWI_CMD_WRITE && cmd->write_len == 0) ||
 465            (cmd->type == MSP_TWI_CMD_READ && cmd->read_len == 0) ||
 466            (cmd->type == MSP_TWI_CMD_WRITE_READ &&
 467            (cmd->read_len == 0 || cmd->write_len == 0))) {
 468                dev_err(&pmcmsptwi_adapter.dev,
 469                        "%s: Cannot transfer less than 1 byte\n",
 470                        __func__);
 471                return -EINVAL;
 472        }
 473
 474        if (cmd->read_len > MSP_MAX_BYTES_PER_RW ||
 475            cmd->write_len > MSP_MAX_BYTES_PER_RW) {
 476                dev_err(&pmcmsptwi_adapter.dev,
 477                        "%s: Cannot transfer more than %d bytes\n",
 478                        __func__, MSP_MAX_BYTES_PER_RW);
 479                return -EINVAL;
 480        }
 481
 482        mutex_lock(&data->lock);
 483        dev_dbg(&pmcmsptwi_adapter.dev,
 484                "Setting address to 0x%04x\n", cmd->addr);
 485        pmcmsptwi_writel(cmd->addr, data->iobase + MSP_TWI_ADD_REG_OFFSET);
 486
 487        if (cmd->type == MSP_TWI_CMD_WRITE ||
 488            cmd->type == MSP_TWI_CMD_WRITE_READ) {
 489                u64 tmp = be64_to_cpup((__be64 *)cmd->write_data);
 490                tmp >>= (MSP_MAX_BYTES_PER_RW - cmd->write_len) * 8;
 491                dev_dbg(&pmcmsptwi_adapter.dev, "Writing 0x%016llx\n", tmp);
 492                pmcmsptwi_writel(tmp & 0x00000000ffffffffLL,
 493                                data->iobase + MSP_TWI_DAT_0_REG_OFFSET);
 494                if (cmd->write_len > 4)
 495                        pmcmsptwi_writel(tmp >> 32,
 496                                data->iobase + MSP_TWI_DAT_1_REG_OFFSET);
 497        }
 498
 499        retval = pmcmsptwi_do_xfer(pmcmsptwi_cmd_to_reg(cmd), data);
 500        if (retval != MSP_TWI_XFER_OK)
 501                goto xfer_err;
 502
 503        if (cmd->type == MSP_TWI_CMD_READ ||
 504            cmd->type == MSP_TWI_CMD_WRITE_READ) {
 505                int i;
 506                u64 rmsk = ~(0xffffffffffffffffLL << (cmd->read_len * 8));
 507                u64 tmp = (u64)pmcmsptwi_readl(data->iobase +
 508                                        MSP_TWI_DAT_0_REG_OFFSET);
 509                if (cmd->read_len > 4)
 510                        tmp |= (u64)pmcmsptwi_readl(data->iobase +
 511                                        MSP_TWI_DAT_1_REG_OFFSET) << 32;
 512                tmp &= rmsk;
 513                dev_dbg(&pmcmsptwi_adapter.dev, "Read 0x%016llx\n", tmp);
 514
 515                for (i = 0; i < cmd->read_len; i++)
 516                        cmd->read_data[i] = tmp >> i;
 517        }
 518
 519xfer_err:
 520        mutex_unlock(&data->lock);
 521
 522        return retval;
 523}
 524
 525/* -- Algorithm functions -- */
 526
 527/*
 528 * Sends an i2c command out on the adapter
 529 */
 530static int pmcmsptwi_master_xfer(struct i2c_adapter *adap,
 531                                struct i2c_msg *msg, int num)
 532{
 533        struct pmcmsptwi_data *data = i2c_get_adapdata(adap);
 534        struct pmcmsptwi_cmd cmd;
 535        struct pmcmsptwi_cfg oldcfg, newcfg;
 536        int ret;
 537
 538        if (num > 2) {
 539                dev_dbg(&adap->dev, "%d messages unsupported\n", num);
 540                return -EINVAL;
 541        } else if (num == 2) {
 542                /* Check for a dual write-then-read command */
 543                struct i2c_msg *nextmsg = msg + 1;
 544                if (!(msg->flags & I2C_M_RD) &&
 545                    (nextmsg->flags & I2C_M_RD) &&
 546                    msg->addr == nextmsg->addr) {
 547                        cmd.type = MSP_TWI_CMD_WRITE_READ;
 548                        cmd.write_len = msg->len;
 549                        cmd.write_data = msg->buf;
 550                        cmd.read_len = nextmsg->len;
 551                        cmd.read_data = nextmsg->buf;
 552                } else {
 553                        dev_dbg(&adap->dev,
 554                                "Non write-read dual messages unsupported\n");
 555                        return -EINVAL;
 556                }
 557        } else if (msg->flags & I2C_M_RD) {
 558                cmd.type = MSP_TWI_CMD_READ;
 559                cmd.read_len = msg->len;
 560                cmd.read_data = msg->buf;
 561                cmd.write_len = 0;
 562                cmd.write_data = NULL;
 563        } else {
 564                cmd.type = MSP_TWI_CMD_WRITE;
 565                cmd.read_len = 0;
 566                cmd.read_data = NULL;
 567                cmd.write_len = msg->len;
 568                cmd.write_data = msg->buf;
 569        }
 570
 571        if (msg->len == 0) {
 572                dev_err(&adap->dev, "Zero-byte messages unsupported\n");
 573                return -EINVAL;
 574        }
 575
 576        cmd.addr = msg->addr;
 577
 578        if (msg->flags & I2C_M_TEN) {
 579                pmcmsptwi_get_twi_config(&newcfg, data);
 580                memcpy(&oldcfg, &newcfg, sizeof(oldcfg));
 581
 582                /* Set the special 10-bit address flag */
 583                newcfg.add10 = 1;
 584
 585                pmcmsptwi_set_twi_config(&newcfg, data);
 586        }
 587
 588        /* Execute the command */
 589        ret = pmcmsptwi_xfer_cmd(&cmd, data);
 590
 591        if (msg->flags & I2C_M_TEN)
 592                pmcmsptwi_set_twi_config(&oldcfg, data);
 593
 594        dev_dbg(&adap->dev, "I2C %s of %d bytes %s\n",
 595                (msg->flags & I2C_M_RD) ? "read" : "write", msg->len,
 596                (ret == MSP_TWI_XFER_OK) ? "succeeded" : "failed");
 597
 598        if (ret != MSP_TWI_XFER_OK) {
 599                /*
 600                 * TODO: We could potentially loop and retry in the case
 601                 * of MSP_TWI_XFER_TIMEOUT.
 602                 */
 603                return -1;
 604        }
 605
 606        return 0;
 607}
 608
 609static u32 pmcmsptwi_i2c_func(struct i2c_adapter *adapter)
 610{
 611        return I2C_FUNC_I2C | I2C_FUNC_10BIT_ADDR |
 612                I2C_FUNC_SMBUS_BYTE | I2C_FUNC_SMBUS_BYTE_DATA |
 613                I2C_FUNC_SMBUS_WORD_DATA | I2C_FUNC_SMBUS_PROC_CALL;
 614}
 615
 616/* -- Initialization -- */
 617
 618static struct i2c_algorithm pmcmsptwi_algo = {
 619        .master_xfer    = pmcmsptwi_master_xfer,
 620        .functionality  = pmcmsptwi_i2c_func,
 621};
 622
 623static struct i2c_adapter pmcmsptwi_adapter = {
 624        .owner          = THIS_MODULE,
 625        .class          = I2C_CLASS_HWMON | I2C_CLASS_SPD,
 626        .algo           = &pmcmsptwi_algo,
 627        .name           = DRV_NAME,
 628};
 629
 630/* work with hotplug and coldplug */
 631MODULE_ALIAS("platform:" DRV_NAME);
 632
 633static struct platform_driver pmcmsptwi_driver = {
 634        .probe  = pmcmsptwi_probe,
 635        .remove = __devexit_p(pmcmsptwi_remove),
 636        .driver = {
 637                .name   = DRV_NAME,
 638                .owner  = THIS_MODULE,
 639        },
 640};
 641
 642static int __init pmcmsptwi_init(void)
 643{
 644        return platform_driver_register(&pmcmsptwi_driver);
 645}
 646
 647static void __exit pmcmsptwi_exit(void)
 648{
 649        platform_driver_unregister(&pmcmsptwi_driver);
 650}
 651
 652MODULE_DESCRIPTION("PMC MSP TWI/SMBus/I2C driver");
 653MODULE_LICENSE("GPL");
 654
 655module_init(pmcmsptwi_init);
 656module_exit(pmcmsptwi_exit);
 657