git.oblomov.eu Git - linux-2.6/blob - drivers/i2c/busses/i2c-pmcmsp.c

   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 */
  68 enum 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 */
  75 enum 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 */
  85 struct pmcmsptwi_clock {
  86         u8 filter;      /* Bits 15:12,  default = 0x03 */
  87         u16 clock;      /* Bits 9:0,    default = 0x001f */
  88 };
  89
  90 struct 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 */
  96 struct 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 */
 106 struct 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 */
 116 struct 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 */
 125 static 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
 136 static 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
 145 static struct pmcmsptwi_data pmcmsptwi_data;
 146
 147 static struct i2c_adapter pmcmsptwi_adapter;
 148
 149 /* inline helper functions */
 150 static inline u32 pmcmsptwi_clock_to_reg(
 151                         const struct pmcmsptwi_clock *clock)
 152 {
 153         return ((clock->filter & 0xf) << 12) | (clock->clock & 0x03ff);
 154 }
 155
 156 static 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
 163 static 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
 173 static 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  */
 186 static 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  */
 200 static 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  */
 212 static 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  */
 224 static 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  */
 252 static 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  */
 273 static 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, res->end - res->start + 1,
 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                                                 res->end - res->start + 1);
 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
 352 ret_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
 362 ret_unreserve:
 363         release_mem_region(res->start, res->end - res->start + 1);
 364
 365 ret_err:
 366         return rc;
 367 }
 368
 369 /*
 370  * Release the device and return 0 if there is one.
 371  */
 372 static 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, res->end - res->start + 1);
 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  */
 397 static 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  */
 425 static 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  */
 448 static 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  */
 458 static 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                         __FUNCTION__);
 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                         __FUNCTION__, 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                 __be64 tmp = cpu_to_be64p((u64 *)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
 519 xfer_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  */
 530 static 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
 609 static 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
 618 static struct i2c_algorithm pmcmsptwi_algo = {
 619         .master_xfer    = pmcmsptwi_master_xfer,
 620         .functionality  = pmcmsptwi_i2c_func,
 621 };
 622
 623 static struct i2c_adapter pmcmsptwi_adapter = {
 624         .owner          = THIS_MODULE,
 625         .class          = I2C_CLASS_HWMON,
 626         .algo           = &pmcmsptwi_algo,
 627         .name           = DRV_NAME,
 628 };
 629
 630 static struct platform_driver pmcmsptwi_driver = {
 631         .probe  = pmcmsptwi_probe,
 632         .remove = __devexit_p(pmcmsptwi_remove),
 633         .driver = {
 634                 .name   = DRV_NAME,
 635                 .owner  = THIS_MODULE,
 636         },
 637 };
 638
 639 static int __init pmcmsptwi_init(void)
 640 {
 641         return platform_driver_register(&pmcmsptwi_driver);
 642 }
 643
 644 static void __exit pmcmsptwi_exit(void)
 645 {
 646         platform_driver_unregister(&pmcmsptwi_driver);
 647 }
 648
 649 MODULE_DESCRIPTION("PMC MSP TWI/SMBus/I2C driver");
 650 MODULE_LICENSE("GPL");
 651
 652 module_init(pmcmsptwi_init);
 653 module_exit(pmcmsptwi_exit);