kernel/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
  23 #include <linux/kernel.h>
  24 #include <linux/module.h>
  25 #include <linux/platform_device.h>
  26 #include <linux/i2c.h>
  27 #include <linux/interrupt.h>
  28 #include <linux/completion.h>
  29 #include <linux/mutex.h>
  30 #include <linux/delay.h>
  31 #include <linux/io.h>
  32
  33 #define DRV_NAME        "pmcmsptwi"
  34
  35 #define MSP_TWI_SF_CLK_REG_OFFSET       0x00
  36 #define MSP_TWI_HS_CLK_REG_OFFSET       0x04
  37 #define MSP_TWI_CFG_REG_OFFSET          0x08
  38 #define MSP_TWI_CMD_REG_OFFSET          0x0c
  39 #define MSP_TWI_ADD_REG_OFFSET          0x10
  40 #define MSP_TWI_DAT_0_REG_OFFSET        0x14
  41 #define MSP_TWI_DAT_1_REG_OFFSET        0x18
  42 #define MSP_TWI_INT_STS_REG_OFFSET      0x1c
  43 #define MSP_TWI_INT_MSK_REG_OFFSET      0x20
  44 #define MSP_TWI_BUSY_REG_OFFSET         0x24
  45
  46 #define MSP_TWI_INT_STS_DONE                    (1 << 0)
  47 #define MSP_TWI_INT_STS_LOST_ARBITRATION        (1 << 1)
  48 #define MSP_TWI_INT_STS_NO_RESPONSE             (1 << 2)
  49 #define MSP_TWI_INT_STS_DATA_COLLISION          (1 << 3)
  50 #define MSP_TWI_INT_STS_BUSY                    (1 << 4)
  51 #define MSP_TWI_INT_STS_ALL                     0x1f
  52
  53 #define MSP_MAX_BYTES_PER_RW            8
  54 #define MSP_MAX_POLL                    5
  55 #define MSP_POLL_DELAY                  10
  56 #define MSP_IRQ_TIMEOUT                 (MSP_MAX_POLL * MSP_POLL_DELAY)
  57
  58 /* IO Operation macros */
  59 #define pmcmsptwi_readl         __raw_readl
  60 #define pmcmsptwi_writel        __raw_writel
  61
  62 /* TWI command type */
  63 enum pmcmsptwi_cmd_type {
  64         MSP_TWI_CMD_WRITE       = 0,    /* Write only */
  65         MSP_TWI_CMD_READ        = 1,    /* Read only */
  66         MSP_TWI_CMD_WRITE_READ  = 2,    /* Write then Read */
  67 };
  68
  69 /* The possible results of the xferCmd */
  70 enum pmcmsptwi_xfer_result {
  71         MSP_TWI_XFER_OK = 0,
  72         MSP_TWI_XFER_TIMEOUT,
  73         MSP_TWI_XFER_BUSY,
  74         MSP_TWI_XFER_DATA_COLLISION,
  75         MSP_TWI_XFER_NO_RESPONSE,
  76         MSP_TWI_XFER_LOST_ARBITRATION,
  77 };
  78
  79 /* Corresponds to a PMCTWI clock configuration register */
  80 struct pmcmsptwi_clock {
  81         u8 filter;      /* Bits 15:12,  default = 0x03 */
  82         u16 clock;      /* Bits 9:0,    default = 0x001f */
  83 };
  84
  85 struct pmcmsptwi_clockcfg {
  86         struct pmcmsptwi_clock standard;  /* The standard/fast clock config */
  87         struct pmcmsptwi_clock highspeed; /* The highspeed clock config */
  88 };
  89
  90 /* Corresponds to the main TWI configuration register */
  91 struct pmcmsptwi_cfg {
  92         u8 arbf;        /* Bits 15:12,  default=0x03 */
  93         u8 nak;         /* Bits 11:8,   default=0x03 */
  94         u8 add10;       /* Bit 7,       default=0x00 */
  95         u8 mst_code;    /* Bits 6:4,    default=0x00 */
  96         u8 arb;         /* Bit 1,       default=0x01 */
  97         u8 highspeed;   /* Bit 0,       default=0x00 */
  98 };
  99
 100 /* A single pmctwi command to issue */
 101 struct pmcmsptwi_cmd {
 102         u16 addr;       /* The slave address (7 or 10 bits) */
 103         enum pmcmsptwi_cmd_type type;   /* The command type */
 104         u8 write_len;   /* Number of bytes in the write buffer */
 105         u8 read_len;    /* Number of bytes in the read buffer */
 106         u8 *write_data; /* Buffer of characters to send */
 107         u8 *read_data;  /* Buffer to fill with incoming data */
 108 };
 109
 110 /* The private data */
 111 struct pmcmsptwi_data {
 112         void __iomem *iobase;                   /* iomapped base for IO */
 113         int irq;                                /* IRQ to use (0 disables) */
 114         struct completion wait;                 /* Completion for xfer */
 115         struct mutex lock;                      /* Used for threadsafeness */
 116         enum pmcmsptwi_xfer_result last_result; /* result of last xfer */
 117 };
 118
 119 /* The default settings */
 120 static const struct pmcmsptwi_clockcfg pmcmsptwi_defclockcfg = {
 121         .standard = {
 122                 .filter = 0x3,
 123                 .clock  = 0x1f,
 124         },
 125         .highspeed = {
 126                 .filter = 0x3,
 127                 .clock  = 0x1f,
 128         },
 129 };
 130
 131 static const struct pmcmsptwi_cfg pmcmsptwi_defcfg = {
 132         .arbf           = 0x03,
 133         .nak            = 0x03,
 134         .add10          = 0x00,
 135         .mst_code       = 0x00,
 136         .arb            = 0x01,
 137         .highspeed      = 0x00,
 138 };
 139
 140 static struct pmcmsptwi_data pmcmsptwi_data;
 141
 142 static struct i2c_adapter pmcmsptwi_adapter;
 143
 144 /* inline helper functions */
 145 static inline u32 pmcmsptwi_clock_to_reg(
 146                         const struct pmcmsptwi_clock *clock)
 147 {
 148         return ((clock->filter & 0xf) << 12) | (clock->clock & 0x03ff);
 149 }
 150
 151 static inline u32 pmcmsptwi_cfg_to_reg(const struct pmcmsptwi_cfg *cfg)
 152 {
 153         return ((cfg->arbf & 0xf) << 12) |
 154                 ((cfg->nak & 0xf) << 8) |
 155                 ((cfg->add10 & 0x1) << 7) |
 156                 ((cfg->mst_code & 0x7) << 4) |
 157                 ((cfg->arb & 0x1) << 1) |
 158                 (cfg->highspeed & 0x1);
 159 }
 160
 161 static inline void pmcmsptwi_reg_to_cfg(u32 reg, struct pmcmsptwi_cfg *cfg)
 162 {
 163         cfg->arbf = (reg >> 12) & 0xf;
 164         cfg->nak = (reg >> 8) & 0xf;
 165         cfg->add10 = (reg >> 7) & 0x1;
 166         cfg->mst_code = (reg >> 4) & 0x7;
 167         cfg->arb = (reg >> 1) & 0x1;
 168         cfg->highspeed = reg & 0x1;
 169 }
 170
 171 /*
 172  * Sets the current clock configuration
 173  */
 174 static void pmcmsptwi_set_clock_config(const struct pmcmsptwi_clockcfg *cfg,
 175                                         struct pmcmsptwi_data *data)
 176 {
 177         mutex_lock(&data->lock);
 178         pmcmsptwi_writel(pmcmsptwi_clock_to_reg(&cfg->standard),
 179                                 data->iobase + MSP_TWI_SF_CLK_REG_OFFSET);
 180         pmcmsptwi_writel(pmcmsptwi_clock_to_reg(&cfg->highspeed),
 181                                 data->iobase + MSP_TWI_HS_CLK_REG_OFFSET);
 182         mutex_unlock(&data->lock);
 183 }
 184
 185 /*
 186  * Gets the current TWI bus configuration
 187  */
 188 static void pmcmsptwi_get_twi_config(struct pmcmsptwi_cfg *cfg,
 189                                         struct pmcmsptwi_data *data)
 190 {
 191         mutex_lock(&data->lock);
 192         pmcmsptwi_reg_to_cfg(pmcmsptwi_readl(
 193                                 data->iobase + MSP_TWI_CFG_REG_OFFSET), cfg);
 194         mutex_unlock(&data->lock);
 195 }
 196
 197 /*
 198  * Sets the current TWI bus configuration
 199  */
 200 static void pmcmsptwi_set_twi_config(const struct pmcmsptwi_cfg *cfg,
 201                                         struct pmcmsptwi_data *data)
 202 {
 203         mutex_lock(&data->lock);
 204         pmcmsptwi_writel(pmcmsptwi_cfg_to_reg(cfg),
 205                                 data->iobase + MSP_TWI_CFG_REG_OFFSET);
 206         mutex_unlock(&data->lock);
 207 }
 208
 209 /*
 210  * Parses the 'int_sts' register and returns a well-defined error code
 211  */
 212 static enum pmcmsptwi_xfer_result pmcmsptwi_get_result(u32 reg)
 213 {
 214         if (reg & MSP_TWI_INT_STS_LOST_ARBITRATION) {
 215                 dev_dbg(&pmcmsptwi_adapter.dev,
 216                         "Result: Lost arbitration\n");
 217                 return MSP_TWI_XFER_LOST_ARBITRATION;
 218         } else if (reg & MSP_TWI_INT_STS_NO_RESPONSE) {
 219                 dev_dbg(&pmcmsptwi_adapter.dev,
 220                         "Result: No response\n");
 221                 return MSP_TWI_XFER_NO_RESPONSE;
 222         } else if (reg & MSP_TWI_INT_STS_DATA_COLLISION) {
 223                 dev_dbg(&pmcmsptwi_adapter.dev,
 224                         "Result: Data collision\n");
 225                 return MSP_TWI_XFER_DATA_COLLISION;
 226         } else if (reg & MSP_TWI_INT_STS_BUSY) {
 227                 dev_dbg(&pmcmsptwi_adapter.dev,
 228                         "Result: Bus busy\n");
 229                 return MSP_TWI_XFER_BUSY;
 230         }
 231
 232         dev_dbg(&pmcmsptwi_adapter.dev, "Result: Operation succeeded\n");
 233         return MSP_TWI_XFER_OK;
 234 }
 235
 236 /*
 237  * In interrupt mode, handle the interrupt.
 238  * NOTE: Assumes data->lock is held.
 239  */
 240 static irqreturn_t pmcmsptwi_interrupt(int irq, void *ptr)
 241 {
 242         struct pmcmsptwi_data *data = ptr;
 243
 244         u32 reason = pmcmsptwi_readl(data->iobase +
 245                                         MSP_TWI_INT_STS_REG_OFFSET);
 246         pmcmsptwi_writel(reason, data->iobase + MSP_TWI_INT_STS_REG_OFFSET);
 247
 248         dev_dbg(&pmcmsptwi_adapter.dev, "Got interrupt 0x%08x\n", reason);
 249         if (!(reason & MSP_TWI_INT_STS_DONE))
 250                 return IRQ_NONE;
 251
 252         data->last_result = pmcmsptwi_get_result(reason);
 253         complete(&data->wait);
 254
 255         return IRQ_HANDLED;
 256 }
 257
 258 /*
 259  * Probe for and register the device and return 0 if there is one.
 260  */
 261 static int pmcmsptwi_probe(struct platform_device *pldev)
 262 {
 263         struct resource *res;
 264         int rc = -ENODEV;
 265
 266         /* get the static platform resources */
 267         res = platform_get_resource(pldev, IORESOURCE_MEM, 0);
 268         if (!res) {
 269                 dev_err(&pldev->dev, "IOMEM resource not found\n");
 270                 goto ret_err;
 271         }
 272
 273         /* reserve the memory region */
 274         if (!request_mem_region(res->start, resource_size(res),
 275                                 pldev->name)) {
 276                 dev_err(&pldev->dev,
 277                         "Unable to get memory/io address region 0x%08x\n",
 278                         res->start);
 279                 rc = -EBUSY;
 280                 goto ret_err;
 281         }
 282
 283         /* remap the memory */
 284         pmcmsptwi_data.iobase = ioremap_nocache(res->start,
 285                                                 resource_size(res));
 286         if (!pmcmsptwi_data.iobase) {
 287                 dev_err(&pldev->dev,
 288                         "Unable to ioremap address 0x%08x\n", res->start);
 289                 rc = -EIO;
 290                 goto ret_unreserve;
 291         }
 292
 293         /* request the irq */
 294         pmcmsptwi_data.irq = platform_get_irq(pldev, 0);
 295         if (pmcmsptwi_data.irq) {
 296                 rc = request_irq(pmcmsptwi_data.irq, &pmcmsptwi_interrupt,
 297                                  IRQF_SHARED, pldev->name, &pmcmsptwi_data);
 298                 if (rc == 0) {
 299                         /*
 300                          * Enable 'DONE' interrupt only.
 301                          *
 302                          * If you enable all interrupts, you will get one on
 303                          * error and another when the operation completes.
 304                          * This way you only have to handle one interrupt,
 305                          * but you can still check all result flags.
 306                          */
 307                         pmcmsptwi_writel(MSP_TWI_INT_STS_DONE,
 308                                         pmcmsptwi_data.iobase +
 309                                         MSP_TWI_INT_MSK_REG_OFFSET);
 310                 } else {
 311                         dev_warn(&pldev->dev,
 312                                 "Could not assign TWI IRQ handler "
 313                                 "to irq %d (continuing with poll)\n",
 314                                 pmcmsptwi_data.irq);
 315                         pmcmsptwi_data.irq = 0;
 316                 }
 317         }
 318
 319         init_completion(&pmcmsptwi_data.wait);
 320         mutex_init(&pmcmsptwi_data.lock);
 321
 322         pmcmsptwi_set_clock_config(&pmcmsptwi_defclockcfg, &pmcmsptwi_data);
 323         pmcmsptwi_set_twi_config(&pmcmsptwi_defcfg, &pmcmsptwi_data);
 324
 325         printk(KERN_INFO DRV_NAME ": Registering MSP71xx I2C adapter\n");
 326
 327         pmcmsptwi_adapter.dev.parent = &pldev->dev;
 328         platform_set_drvdata(pldev, &pmcmsptwi_adapter);
 329         i2c_set_adapdata(&pmcmsptwi_adapter, &pmcmsptwi_data);
 330
 331         rc = i2c_add_adapter(&pmcmsptwi_adapter);
 332         if (rc) {
 333                 dev_err(&pldev->dev, "Unable to register I2C adapter\n");
 334                 goto ret_unmap;
 335         }
 336
 337         return 0;
 338
 339 ret_unmap:
 340         if (pmcmsptwi_data.irq) {
 341                 pmcmsptwi_writel(0,
 342                         pmcmsptwi_data.iobase + MSP_TWI_INT_MSK_REG_OFFSET);
 343                 free_irq(pmcmsptwi_data.irq, &pmcmsptwi_data);
 344         }
 345
 346         iounmap(pmcmsptwi_data.iobase);
 347
 348 ret_unreserve:
 349         release_mem_region(res->start, resource_size(res));
 350
 351 ret_err:
 352         return rc;
 353 }
 354
 355 /*
 356  * Release the device and return 0 if there is one.
 357  */
 358 static int pmcmsptwi_remove(struct platform_device *pldev)
 359 {
 360         struct resource *res;
 361
 362         i2c_del_adapter(&pmcmsptwi_adapter);
 363
 364         if (pmcmsptwi_data.irq) {
 365                 pmcmsptwi_writel(0,
 366                         pmcmsptwi_data.iobase + MSP_TWI_INT_MSK_REG_OFFSET);
 367                 free_irq(pmcmsptwi_data.irq, &pmcmsptwi_data);
 368         }
 369
 370         iounmap(pmcmsptwi_data.iobase);
 371
 372         res = platform_get_resource(pldev, IORESOURCE_MEM, 0);
 373         release_mem_region(res->start, resource_size(res));
 374
 375         return 0;
 376 }
 377
 378 /*
 379  * Polls the 'busy' register until the command is complete.
 380  * NOTE: Assumes data->lock is held.
 381  */
 382 static void pmcmsptwi_poll_complete(struct pmcmsptwi_data *data)
 383 {
 384         int i;
 385
 386         for (i = 0; i < MSP_MAX_POLL; i++) {
 387                 u32 val = pmcmsptwi_readl(data->iobase +
 388                                                 MSP_TWI_BUSY_REG_OFFSET);
 389                 if (val == 0) {
 390                         u32 reason = pmcmsptwi_readl(data->iobase +
 391                                                 MSP_TWI_INT_STS_REG_OFFSET);
 392                         pmcmsptwi_writel(reason, data->iobase +
 393                                                 MSP_TWI_INT_STS_REG_OFFSET);
 394                         data->last_result = pmcmsptwi_get_result(reason);
 395                         return;
 396                 }
 397                 udelay(MSP_POLL_DELAY);
 398         }
 399
 400         dev_dbg(&pmcmsptwi_adapter.dev, "Result: Poll timeout\n");
 401         data->last_result = MSP_TWI_XFER_TIMEOUT;
 402 }
 403
 404 /*
 405  * Do the transfer (low level):
 406  *   May use interrupt-driven or polling, depending on if an IRQ is
 407  *   presently registered.
 408  * NOTE: Assumes data->lock is held.
 409  */
 410 static enum pmcmsptwi_xfer_result pmcmsptwi_do_xfer(
 411                         u32 reg, struct pmcmsptwi_data *data)
 412 {
 413         dev_dbg(&pmcmsptwi_adapter.dev, "Writing cmd reg 0x%08x\n", reg);
 414         pmcmsptwi_writel(reg, data->iobase + MSP_TWI_CMD_REG_OFFSET);
 415         if (data->irq) {
 416                 unsigned long timeleft = wait_for_completion_timeout(
 417                                                 &data->wait, MSP_IRQ_TIMEOUT);
 418                 if (timeleft == 0) {
 419                         dev_dbg(&pmcmsptwi_adapter.dev,
 420                                 "Result: IRQ timeout\n");
 421                         complete(&data->wait);
 422                         data->last_result = MSP_TWI_XFER_TIMEOUT;
 423                 }
 424         } else
 425                 pmcmsptwi_poll_complete(data);
 426
 427         return data->last_result;
 428 }
 429
 430 /*
 431  * Helper routine, converts 'pmctwi_cmd' struct to register format
 432  */
 433 static inline u32 pmcmsptwi_cmd_to_reg(const struct pmcmsptwi_cmd *cmd)
 434 {
 435         return ((cmd->type & 0x3) << 8) |
 436                 (((cmd->write_len - 1) & 0x7) << 4) |
 437                 ((cmd->read_len - 1) & 0x7);
 438 }
 439
 440 /*
 441  * Do the transfer (high level)
 442  */
 443 static enum pmcmsptwi_xfer_result pmcmsptwi_xfer_cmd(
 444                         struct pmcmsptwi_cmd *cmd,
 445                         struct pmcmsptwi_data *data)
 446 {
 447         enum pmcmsptwi_xfer_result retval;
 448
 449         if ((cmd->type == MSP_TWI_CMD_WRITE && cmd->write_len == 0) ||
 450             (cmd->type == MSP_TWI_CMD_READ && cmd->read_len == 0) ||
 451             (cmd->type == MSP_TWI_CMD_WRITE_READ &&
 452             (cmd->read_len == 0 || cmd->write_len == 0))) {
 453                 dev_err(&pmcmsptwi_adapter.dev,
 454                         "%s: Cannot transfer less than 1 byte\n",
 455                         __func__);
 456                 return -EINVAL;
 457         }
 458
 459         mutex_lock(&data->lock);
 460         dev_dbg(&pmcmsptwi_adapter.dev,
 461                 "Setting address to 0x%04x\n", cmd->addr);
 462         pmcmsptwi_writel(cmd->addr, data->iobase + MSP_TWI_ADD_REG_OFFSET);
 463
 464         if (cmd->type == MSP_TWI_CMD_WRITE ||
 465             cmd->type == MSP_TWI_CMD_WRITE_READ) {
 466                 u64 tmp = be64_to_cpup((__be64 *)cmd->write_data);
 467                 tmp >>= (MSP_MAX_BYTES_PER_RW - cmd->write_len) * 8;
 468                 dev_dbg(&pmcmsptwi_adapter.dev, "Writing 0x%016llx\n", tmp);
 469                 pmcmsptwi_writel(tmp & 0x00000000ffffffffLL,
 470                                 data->iobase + MSP_TWI_DAT_0_REG_OFFSET);
 471                 if (cmd->write_len > 4)
 472                         pmcmsptwi_writel(tmp >> 32,
 473                                 data->iobase + MSP_TWI_DAT_1_REG_OFFSET);
 474         }
 475
 476         retval = pmcmsptwi_do_xfer(pmcmsptwi_cmd_to_reg(cmd), data);
 477         if (retval != MSP_TWI_XFER_OK)
 478                 goto xfer_err;
 479
 480         if (cmd->type == MSP_TWI_CMD_READ ||
 481             cmd->type == MSP_TWI_CMD_WRITE_READ) {
 482                 int i;
 483                 u64 rmsk = ~(0xffffffffffffffffLL << (cmd->read_len * 8));
 484                 u64 tmp = (u64)pmcmsptwi_readl(data->iobase +
 485                                         MSP_TWI_DAT_0_REG_OFFSET);
 486                 if (cmd->read_len > 4)
 487                         tmp |= (u64)pmcmsptwi_readl(data->iobase +
 488                                         MSP_TWI_DAT_1_REG_OFFSET) << 32;
 489                 tmp &= rmsk;
 490                 dev_dbg(&pmcmsptwi_adapter.dev, "Read 0x%016llx\n", tmp);
 491
 492                 for (i = 0; i < cmd->read_len; i++)
 493                         cmd->read_data[i] = tmp >> i;
 494         }
 495
 496 xfer_err:
 497         mutex_unlock(&data->lock);
 498
 499         return retval;
 500 }
 501
 502 /* -- Algorithm functions -- */
 503
 504 /*
 505  * Sends an i2c command out on the adapter
 506  */
 507 static int pmcmsptwi_master_xfer(struct i2c_adapter *adap,
 508                                 struct i2c_msg *msg, int num)
 509 {
 510         struct pmcmsptwi_data *data = i2c_get_adapdata(adap);
 511         struct pmcmsptwi_cmd cmd;
 512         struct pmcmsptwi_cfg oldcfg, newcfg;
 513         int ret;
 514
 515         if (num == 2) {
 516                 struct i2c_msg *nextmsg = msg + 1;
 517
 518                 cmd.type = MSP_TWI_CMD_WRITE_READ;
 519                 cmd.write_len = msg->len;
 520                 cmd.write_data = msg->buf;
 521                 cmd.read_len = nextmsg->len;
 522                 cmd.read_data = nextmsg->buf;
 523         } else if (msg->flags & I2C_M_RD) {
 524                 cmd.type = MSP_TWI_CMD_READ;
 525                 cmd.read_len = msg->len;
 526                 cmd.read_data = msg->buf;
 527                 cmd.write_len = 0;
 528                 cmd.write_data = NULL;
 529         } else {
 530                 cmd.type = MSP_TWI_CMD_WRITE;
 531                 cmd.read_len = 0;
 532                 cmd.read_data = NULL;
 533                 cmd.write_len = msg->len;
 534                 cmd.write_data = msg->buf;
 535         }
 536
 537         if (msg->len == 0) {
 538                 dev_err(&adap->dev, "Zero-byte messages unsupported\n");
 539                 return -EINVAL;
 540         }
 541
 542         cmd.addr = msg->addr;
 543
 544         if (msg->flags & I2C_M_TEN) {
 545                 pmcmsptwi_get_twi_config(&newcfg, data);
 546                 memcpy(&oldcfg, &newcfg, sizeof(oldcfg));
 547
 548                 /* Set the special 10-bit address flag */
 549                 newcfg.add10 = 1;
 550
 551                 pmcmsptwi_set_twi_config(&newcfg, data);
 552         }
 553
 554         /* Execute the command */
 555         ret = pmcmsptwi_xfer_cmd(&cmd, data);
 556
 557         if (msg->flags & I2C_M_TEN)
 558                 pmcmsptwi_set_twi_config(&oldcfg, data);
 559
 560         dev_dbg(&adap->dev, "I2C %s of %d bytes %s\n",
 561                 (msg->flags & I2C_M_RD) ? "read" : "write", msg->len,
 562                 (ret == MSP_TWI_XFER_OK) ? "succeeded" : "failed");
 563
 564         if (ret != MSP_TWI_XFER_OK) {
 565                 /*
 566                  * TODO: We could potentially loop and retry in the case
 567                  * of MSP_TWI_XFER_TIMEOUT.
 568                  */
 569                 return -1;
 570         }
 571
 572         return 0;
 573 }
 574
 575 static u32 pmcmsptwi_i2c_func(struct i2c_adapter *adapter)
 576 {
 577         return I2C_FUNC_I2C | I2C_FUNC_10BIT_ADDR |
 578                 I2C_FUNC_SMBUS_BYTE | I2C_FUNC_SMBUS_BYTE_DATA |
 579                 I2C_FUNC_SMBUS_WORD_DATA | I2C_FUNC_SMBUS_PROC_CALL;
 580 }
 581
 582 static struct i2c_adapter_quirks pmcmsptwi_i2c_quirks = {
 583         .flags = I2C_AQ_COMB_WRITE_THEN_READ,
 584         .max_write_len = MSP_MAX_BYTES_PER_RW,
 585         .max_read_len = MSP_MAX_BYTES_PER_RW,
 586         .max_comb_1st_msg_len = MSP_MAX_BYTES_PER_RW,
 587         .max_comb_2nd_msg_len = MSP_MAX_BYTES_PER_RW,
 588 };
 589
 590 /* -- Initialization -- */
 591
 592 static struct i2c_algorithm pmcmsptwi_algo = {
 593         .master_xfer    = pmcmsptwi_master_xfer,
 594         .functionality  = pmcmsptwi_i2c_func,
 595 };
 596
 597 static struct i2c_adapter pmcmsptwi_adapter = {
 598         .owner          = THIS_MODULE,
 599         .class          = I2C_CLASS_HWMON | I2C_CLASS_SPD,
 600         .algo           = &pmcmsptwi_algo,
 601         .quirks         = &pmcmsptwi_i2c_quirks,
 602         .name           = DRV_NAME,
 603 };
 604
 605 static struct platform_driver pmcmsptwi_driver = {
 606         .probe  = pmcmsptwi_probe,
 607         .remove = pmcmsptwi_remove,
 608         .driver = {
 609                 .name   = DRV_NAME,
 610         },
 611 };
 612
 613 module_platform_driver(pmcmsptwi_driver);
 614
 615 MODULE_DESCRIPTION("PMC MSP TWI/SMBus/I2C driver");
 616 MODULE_LICENSE("GPL");
 617 MODULE_ALIAS("platform:" DRV_NAME);