drivers/i2c/busses/i2c-s3c2410.c

   1 /* linux/drivers/i2c/busses/i2c-s3c2410.c
   2  *
   3  * Copyright (C) 2004,2005,2009 Simtec Electronics
   4  *      Ben Dooks <ben@simtec.co.uk>
   5  *
   6  * S3C2410 I2C Controller
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * along with this program; if not, write to the Free Software
  20  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  21 */
  22
  23 #include <linux/kernel.h>
  24 #include <linux/module.h>
  25
  26 #include <linux/i2c.h>
  27 #include <linux/init.h>
  28 #include <linux/time.h>
  29 #include <linux/interrupt.h>
  30 #include <linux/delay.h>
  31 #include <linux/errno.h>
  32 #include <linux/err.h>
  33 #include <linux/platform_device.h>
  34 #include <linux/clk.h>
  35 #include <linux/cpufreq.h>
  36 #include <linux/slab.h>
  37 #include <linux/io.h>
  38
  39 #include <asm/irq.h>
  40
  41 #include <plat/regs-iic.h>
  42 #include <plat/iic.h>
  43
  44 /* i2c controller state */
  45
  46 enum s3c24xx_i2c_state {
  47         STATE_IDLE,
  48         STATE_START,
  49         STATE_READ,
  50         STATE_WRITE,
  51         STATE_STOP
  52 };
  53
  54 enum s3c24xx_i2c_type {
  55         TYPE_S3C2410,
  56         TYPE_S3C2440,
  57 };
  58
  59 struct s3c24xx_i2c {
  60         spinlock_t              lock;
  61         wait_queue_head_t       wait;
  62         unsigned int            suspended:1;
  63
  64         struct i2c_msg          *msg;
  65         unsigned int            msg_num;
  66         unsigned int            msg_idx;
  67         unsigned int            msg_ptr;
  68
  69         unsigned int            tx_setup;
  70         unsigned int            irq;
  71
  72         enum s3c24xx_i2c_state  state;
  73         unsigned long           clkrate;
  74
  75         void __iomem            *regs;
  76         struct clk              *clk;
  77         struct device           *dev;
  78         struct resource         *ioarea;
  79         struct i2c_adapter      adap;
  80
  81 #ifdef CONFIG_CPU_FREQ
  82         struct notifier_block   freq_transition;
  83 #endif
  84 };
  85
  86 /* default platform data removed, dev should always carry data. */
  87
  88 /* s3c24xx_i2c_is2440()
  89  *
  90  * return true is this is an s3c2440
  91 */
  92
  93 static inline int s3c24xx_i2c_is2440(struct s3c24xx_i2c *i2c)
  94 {
  95         struct platform_device *pdev = to_platform_device(i2c->dev);
  96         enum s3c24xx_i2c_type type;
  97
  98         type = platform_get_device_id(pdev)->driver_data;
  99         return type == TYPE_S3C2440;
 100 }
 101
 102 /* s3c24xx_i2c_master_complete
 103  *
 104  * complete the message and wake up the caller, using the given return code,
 105  * or zero to mean ok.
 106 */
 107
 108 static inline void s3c24xx_i2c_master_complete(struct s3c24xx_i2c *i2c, int ret)
 109 {
 110         dev_dbg(i2c->dev, "master_complete %d\n", ret);
 111
 112         i2c->msg_ptr = 0;
 113         i2c->msg = NULL;
 114         i2c->msg_idx++;
 115         i2c->msg_num = 0;
 116         if (ret)
 117                 i2c->msg_idx = ret;
 118
 119         wake_up(&i2c->wait);
 120 }
 121
 122 static inline void s3c24xx_i2c_disable_ack(struct s3c24xx_i2c *i2c)
 123 {
 124         unsigned long tmp;
 125
 126         tmp = readl(i2c->regs + S3C2410_IICCON);
 127         writel(tmp & ~S3C2410_IICCON_ACKEN, i2c->regs + S3C2410_IICCON);
 128 }
 129
 130 static inline void s3c24xx_i2c_enable_ack(struct s3c24xx_i2c *i2c)
 131 {
 132         unsigned long tmp;
 133
 134         tmp = readl(i2c->regs + S3C2410_IICCON);
 135         writel(tmp | S3C2410_IICCON_ACKEN, i2c->regs + S3C2410_IICCON);
 136 }
 137
 138 /* irq enable/disable functions */
 139
 140 static inline void s3c24xx_i2c_disable_irq(struct s3c24xx_i2c *i2c)
 141 {
 142         unsigned long tmp;
 143
 144         tmp = readl(i2c->regs + S3C2410_IICCON);
 145         writel(tmp & ~S3C2410_IICCON_IRQEN, i2c->regs + S3C2410_IICCON);
 146 }
 147
 148 static inline void s3c24xx_i2c_enable_irq(struct s3c24xx_i2c *i2c)
 149 {
 150         unsigned long tmp;
 151
 152         tmp = readl(i2c->regs + S3C2410_IICCON);
 153         writel(tmp | S3C2410_IICCON_IRQEN, i2c->regs + S3C2410_IICCON);
 154 }
 155
 156
 157 /* s3c24xx_i2c_message_start
 158  *
 159  * put the start of a message onto the bus
 160 */
 161
 162 static void s3c24xx_i2c_message_start(struct s3c24xx_i2c *i2c,
 163                                       struct i2c_msg *msg)
 164 {
 165         unsigned int addr = (msg->addr & 0x7f) << 1;
 166         unsigned long stat;
 167         unsigned long iiccon;
 168
 169         stat = 0;
 170         stat |=  S3C2410_IICSTAT_TXRXEN;
 171
 172         if (msg->flags & I2C_M_RD) {
 173                 stat |= S3C2410_IICSTAT_MASTER_RX;
 174                 addr |= 1;
 175         } else
 176                 stat |= S3C2410_IICSTAT_MASTER_TX;
 177
 178         if (msg->flags & I2C_M_REV_DIR_ADDR)
 179                 addr ^= 1;
 180
 181         /* todo - check for wether ack wanted or not */
 182         s3c24xx_i2c_enable_ack(i2c);
 183
 184         iiccon = readl(i2c->regs + S3C2410_IICCON);
 185         writel(stat, i2c->regs + S3C2410_IICSTAT);
 186
 187         dev_dbg(i2c->dev, "START: %08lx to IICSTAT, %02x to DS\n", stat, addr);
 188         writeb(addr, i2c->regs + S3C2410_IICDS);
 189
 190         /* delay here to ensure the data byte has gotten onto the bus
 191          * before the transaction is started */
 192
 193         ndelay(i2c->tx_setup);
 194
 195         dev_dbg(i2c->dev, "iiccon, %08lx\n", iiccon);
 196         writel(iiccon, i2c->regs + S3C2410_IICCON);
 197
 198         stat |= S3C2410_IICSTAT_START;
 199         writel(stat, i2c->regs + S3C2410_IICSTAT);
 200 }
 201
 202 static inline void s3c24xx_i2c_stop(struct s3c24xx_i2c *i2c, int ret)
 203 {
 204         unsigned long iicstat = readl(i2c->regs + S3C2410_IICSTAT);
 205
 206         dev_dbg(i2c->dev, "STOP\n");
 207
 208         /* stop the transfer */
 209         iicstat &= ~S3C2410_IICSTAT_START;
 210         writel(iicstat, i2c->regs + S3C2410_IICSTAT);
 211
 212         i2c->state = STATE_STOP;
 213
 214         s3c24xx_i2c_master_complete(i2c, ret);
 215         s3c24xx_i2c_disable_irq(i2c);
 216 }
 217
 218 /* helper functions to determine the current state in the set of
 219  * messages we are sending */
 220
 221 /* is_lastmsg()
 222  *
 223  * returns TRUE if the current message is the last in the set
 224 */
 225
 226 static inline int is_lastmsg(struct s3c24xx_i2c *i2c)
 227 {
 228         return i2c->msg_idx >= (i2c->msg_num - 1);
 229 }
 230
 231 /* is_msglast
 232  *
 233  * returns TRUE if we this is the last byte in the current message
 234 */
 235
 236 static inline int is_msglast(struct s3c24xx_i2c *i2c)
 237 {
 238         return i2c->msg_ptr == i2c->msg->len-1;
 239 }
 240
 241 /* is_msgend
 242  *
 243  * returns TRUE if we reached the end of the current message
 244 */
 245
 246 static inline int is_msgend(struct s3c24xx_i2c *i2c)
 247 {
 248         return i2c->msg_ptr >= i2c->msg->len;
 249 }
 250
 251 /* i2c_s3c_irq_nextbyte
 252  *
 253  * process an interrupt and work out what to do
 254  */
 255
 256 static int i2c_s3c_irq_nextbyte(struct s3c24xx_i2c *i2c, unsigned long iicstat)
 257 {
 258         unsigned long tmp;
 259         unsigned char byte;
 260         int ret = 0;
 261
 262         switch (i2c->state) {
 263
 264         case STATE_IDLE:
 265                 dev_err(i2c->dev, "%s: called in STATE_IDLE\n", __func__);
 266                 goto out;
 267
 268         case STATE_STOP:
 269                 dev_err(i2c->dev, "%s: called in STATE_STOP\n", __func__);
 270                 s3c24xx_i2c_disable_irq(i2c);
 271                 goto out_ack;
 272
 273         case STATE_START:
 274                 /* last thing we did was send a start condition on the
 275                  * bus, or started a new i2c message
 276                  */
 277
 278                 if (iicstat & S3C2410_IICSTAT_LASTBIT &&
 279                     !(i2c->msg->flags & I2C_M_IGNORE_NAK)) {
 280                         /* ack was not received... */
 281
 282                         dev_dbg(i2c->dev, "ack was not received\n");
 283                         s3c24xx_i2c_stop(i2c, -ENXIO);
 284                         goto out_ack;
 285                 }
 286
 287                 if (i2c->msg->flags & I2C_M_RD)
 288                         i2c->state = STATE_READ;
 289                 else
 290                         i2c->state = STATE_WRITE;
 291
 292                 /* terminate the transfer if there is nothing to do
 293                  * as this is used by the i2c probe to find devices. */
 294
 295                 if (is_lastmsg(i2c) && i2c->msg->len == 0) {
 296                         s3c24xx_i2c_stop(i2c, 0);
 297                         goto out_ack;
 298                 }
 299
 300                 if (i2c->state == STATE_READ)
 301                         goto prepare_read;
 302
 303                 /* fall through to the write state, as we will need to
 304                  * send a byte as well */
 305
 306         case STATE_WRITE:
 307                 /* we are writing data to the device... check for the
 308                  * end of the message, and if so, work out what to do
 309                  */
 310
 311                 if (!(i2c->msg->flags & I2C_M_IGNORE_NAK)) {
 312                         if (iicstat & S3C2410_IICSTAT_LASTBIT) {
 313                                 dev_dbg(i2c->dev, "WRITE: No Ack\n");
 314
 315                                 s3c24xx_i2c_stop(i2c, -ECONNREFUSED);
 316                                 goto out_ack;
 317                         }
 318                 }
 319
 320  retry_write:
 321
 322                 if (!is_msgend(i2c)) {
 323                         byte = i2c->msg->buf[i2c->msg_ptr++];
 324                         writeb(byte, i2c->regs + S3C2410_IICDS);
 325
 326                         /* delay after writing the byte to allow the
 327                          * data setup time on the bus, as writing the
 328                          * data to the register causes the first bit
 329                          * to appear on SDA, and SCL will change as
 330                          * soon as the interrupt is acknowledged */
 331
 332                         ndelay(i2c->tx_setup);
 333
 334                 } else if (!is_lastmsg(i2c)) {
 335                         /* we need to go to the next i2c message */
 336
 337                         dev_dbg(i2c->dev, "WRITE: Next Message\n");
 338
 339                         i2c->msg_ptr = 0;
 340                         i2c->msg_idx++;
 341                         i2c->msg++;
 342
 343                         /* check to see if we need to do another message */
 344                         if (i2c->msg->flags & I2C_M_NOSTART) {
 345
 346                                 if (i2c->msg->flags & I2C_M_RD) {
 347                                         /* cannot do this, the controller
 348                                          * forces us to send a new START
 349                                          * when we change direction */
 350
 351                                         s3c24xx_i2c_stop(i2c, -EINVAL);
 352                                 }
 353
 354                                 goto retry_write;
 355                         } else {
 356                                 /* send the new start */
 357                                 s3c24xx_i2c_message_start(i2c, i2c->msg);
 358                                 i2c->state = STATE_START;
 359                         }
 360
 361                 } else {
 362                         /* send stop */
 363
 364                         s3c24xx_i2c_stop(i2c, 0);
 365                 }
 366                 break;
 367
 368         case STATE_READ:
 369                 /* we have a byte of data in the data register, do
 370                  * something with it, and then work out wether we are
 371                  * going to do any more read/write
 372                  */
 373
 374                 byte = readb(i2c->regs + S3C2410_IICDS);
 375                 i2c->msg->buf[i2c->msg_ptr++] = byte;
 376
 377  prepare_read:
 378                 if (is_msglast(i2c)) {
 379                         /* last byte of buffer */
 380
 381                         if (is_lastmsg(i2c))
 382                                 s3c24xx_i2c_disable_ack(i2c);
 383
 384                 } else if (is_msgend(i2c)) {
 385                         /* ok, we've read the entire buffer, see if there
 386                          * is anything else we need to do */
 387
 388                         if (is_lastmsg(i2c)) {
 389                                 /* last message, send stop and complete */
 390                                 dev_dbg(i2c->dev, "READ: Send Stop\n");
 391
 392                                 s3c24xx_i2c_stop(i2c, 0);
 393                         } else {
 394                                 /* go to the next transfer */
 395                                 dev_dbg(i2c->dev, "READ: Next Transfer\n");
 396
 397                                 i2c->msg_ptr = 0;
 398                                 i2c->msg_idx++;
 399                                 i2c->msg++;
 400                         }
 401                 }
 402
 403                 break;
 404         }
 405
 406         /* acknowlegde the IRQ and get back on with the work */
 407
 408  out_ack:
 409         tmp = readl(i2c->regs + S3C2410_IICCON);
 410         tmp &= ~S3C2410_IICCON_IRQPEND;
 411         writel(tmp, i2c->regs + S3C2410_IICCON);
 412  out:
 413         return ret;
 414 }
 415
 416 /* s3c24xx_i2c_irq
 417  *
 418  * top level IRQ servicing routine
 419 */
 420
 421 static irqreturn_t s3c24xx_i2c_irq(int irqno, void *dev_id)
 422 {
 423         struct s3c24xx_i2c *i2c = dev_id;
 424         unsigned long status;
 425         unsigned long tmp;
 426
 427         status = readl(i2c->regs + S3C2410_IICSTAT);
 428
 429         if (status & S3C2410_IICSTAT_ARBITR) {
 430                 /* deal with arbitration loss */
 431                 dev_err(i2c->dev, "deal with arbitration loss\n");
 432         }
 433
 434         if (i2c->state == STATE_IDLE) {
 435                 dev_dbg(i2c->dev, "IRQ: error i2c->state == IDLE\n");
 436
 437                 tmp = readl(i2c->regs + S3C2410_IICCON);
 438                 tmp &= ~S3C2410_IICCON_IRQPEND;
 439                 writel(tmp, i2c->regs +  S3C2410_IICCON);
 440                 goto out;
 441         }
 442
 443         /* pretty much this leaves us with the fact that we've
 444          * transmitted or received whatever byte we last sent */
 445
 446         i2c_s3c_irq_nextbyte(i2c, status);
 447
 448  out:
 449         return IRQ_HANDLED;
 450 }
 451
 452
 453 /* s3c24xx_i2c_set_master
 454  *
 455  * get the i2c bus for a master transaction
 456 */
 457
 458 static int s3c24xx_i2c_set_master(struct s3c24xx_i2c *i2c)
 459 {
 460         unsigned long iicstat;
 461         int timeout = 400;
 462
 463         while (timeout-- > 0) {
 464                 iicstat = readl(i2c->regs + S3C2410_IICSTAT);
 465
 466                 if (!(iicstat & S3C2410_IICSTAT_BUSBUSY))
 467                         return 0;
 468
 469                 msleep(1);
 470         }
 471
 472         return -ETIMEDOUT;
 473 }
 474
 475 /* s3c24xx_i2c_doxfer
 476  *
 477  * this starts an i2c transfer
 478 */
 479
 480 static int s3c24xx_i2c_doxfer(struct s3c24xx_i2c *i2c,
 481                               struct i2c_msg *msgs, int num)
 482 {
 483         unsigned long iicstat, timeout;
 484         int spins = 20;
 485         int ret;
 486
 487         if (i2c->suspended)
 488                 return -EIO;
 489
 490         ret = s3c24xx_i2c_set_master(i2c);
 491         if (ret != 0) {
 492                 dev_err(i2c->dev, "cannot get bus (error %d)\n", ret);
 493                 ret = -EAGAIN;
 494                 goto out;
 495         }
 496
 497         spin_lock_irq(&i2c->lock);
 498
 499         i2c->msg     = msgs;
 500         i2c->msg_num = num;
 501         i2c->msg_ptr = 0;
 502         i2c->msg_idx = 0;
 503         i2c->state   = STATE_START;
 504
 505         s3c24xx_i2c_enable_irq(i2c);
 506         s3c24xx_i2c_message_start(i2c, msgs);
 507         spin_unlock_irq(&i2c->lock);
 508
 509         timeout = wait_event_timeout(i2c->wait, i2c->msg_num == 0, HZ * 5);
 510
 511         ret = i2c->msg_idx;
 512
 513         /* having these next two as dev_err() makes life very
 514          * noisy when doing an i2cdetect */
 515
 516         if (timeout == 0)
 517                 dev_dbg(i2c->dev, "timeout\n");
 518         else if (ret != num)
 519                 dev_dbg(i2c->dev, "incomplete xfer (%d)\n", ret);
 520
 521         /* ensure the stop has been through the bus */
 522
 523         dev_dbg(i2c->dev, "waiting for bus idle\n");
 524
 525         /* first, try busy waiting briefly */
 526         do {
 527                 iicstat = readl(i2c->regs + S3C2410_IICSTAT);
 528         } while ((iicstat & S3C2410_IICSTAT_START) && --spins);
 529
 530         /* if that timed out sleep */
 531         if (!spins) {
 532                 msleep(1);
 533                 iicstat = readl(i2c->regs + S3C2410_IICSTAT);
 534         }
 535
 536         if (iicstat & S3C2410_IICSTAT_START)
 537                 dev_warn(i2c->dev, "timeout waiting for bus idle\n");
 538
 539  out:
 540         return ret;
 541 }
 542
 543 /* s3c24xx_i2c_xfer
 544  *
 545  * first port of call from the i2c bus code when an message needs
 546  * transferring across the i2c bus.
 547 */
 548
 549 static int s3c24xx_i2c_xfer(struct i2c_adapter *adap,
 550                         struct i2c_msg *msgs, int num)
 551 {
 552         struct s3c24xx_i2c *i2c = (struct s3c24xx_i2c *)adap->algo_data;
 553         int retry;
 554         int ret;
 555
 556         clk_enable(i2c->clk);
 557
 558         for (retry = 0; retry < adap->retries; retry++) {
 559
 560                 ret = s3c24xx_i2c_doxfer(i2c, msgs, num);
 561
 562                 if (ret != -EAGAIN) {
 563                         clk_disable(i2c->clk);
 564                         return ret;
 565                 }
 566
 567                 dev_dbg(i2c->dev, "Retrying transmission (%d)\n", retry);
 568
 569                 udelay(100);
 570         }
 571
 572         clk_disable(i2c->clk);
 573         return -EREMOTEIO;
 574 }
 575
 576 /* declare our i2c functionality */
 577 static u32 s3c24xx_i2c_func(struct i2c_adapter *adap)
 578 {
 579         return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_PROTOCOL_MANGLING;
 580 }
 581
 582 /* i2c bus registration info */
 583
 584 static const struct i2c_algorithm s3c24xx_i2c_algorithm = {
 585         .master_xfer            = s3c24xx_i2c_xfer,
 586         .functionality          = s3c24xx_i2c_func,
 587 };
 588
 589 /* s3c24xx_i2c_calcdivisor
 590  *
 591  * return the divisor settings for a given frequency
 592 */
 593
 594 static int s3c24xx_i2c_calcdivisor(unsigned long clkin, unsigned int wanted,
 595                                    unsigned int *div1, unsigned int *divs)
 596 {
 597         unsigned int calc_divs = clkin / wanted;
 598         unsigned int calc_div1;
 599
 600         if (calc_divs > (16*16))
 601                 calc_div1 = 512;
 602         else
 603                 calc_div1 = 16;
 604
 605         calc_divs += calc_div1-1;
 606         calc_divs /= calc_div1;
 607
 608         if (calc_divs == 0)
 609                 calc_divs = 1;
 610         if (calc_divs > 17)
 611                 calc_divs = 17;
 612
 613         *divs = calc_divs;
 614         *div1 = calc_div1;
 615
 616         return clkin / (calc_divs * calc_div1);
 617 }
 618
 619 /* s3c24xx_i2c_clockrate
 620  *
 621  * work out a divisor for the user requested frequency setting,
 622  * either by the requested frequency, or scanning the acceptable
 623  * range of frequencies until something is found
 624 */
 625
 626 static int s3c24xx_i2c_clockrate(struct s3c24xx_i2c *i2c, unsigned int *got)
 627 {
 628         struct s3c2410_platform_i2c *pdata = i2c->dev->platform_data;
 629         unsigned long clkin = clk_get_rate(i2c->clk);
 630         unsigned int divs, div1;
 631         unsigned long target_frequency;
 632         u32 iiccon;
 633         int freq;
 634
 635         i2c->clkrate = clkin;
 636         clkin /= 1000;          /* clkin now in KHz */
 637
 638         dev_dbg(i2c->dev, "pdata desired frequency %lu\n", pdata->frequency);
 639
 640         target_frequency = pdata->frequency ? pdata->frequency : 100000;
 641
 642         target_frequency /= 1000; /* Target frequency now in KHz */
 643
 644         freq = s3c24xx_i2c_calcdivisor(clkin, target_frequency, &div1, &divs);
 645
 646         if (freq > target_frequency) {
 647                 dev_err(i2c->dev,
 648                         "Unable to achieve desired frequency %luKHz."   \
 649                         " Lowest achievable %dKHz\n", target_frequency, freq);
 650                 return -EINVAL;
 651         }
 652
 653         *got = freq;
 654
 655         iiccon = readl(i2c->regs + S3C2410_IICCON);
 656         iiccon &= ~(S3C2410_IICCON_SCALEMASK | S3C2410_IICCON_TXDIV_512);
 657         iiccon |= (divs-1);
 658
 659         if (div1 == 512)
 660                 iiccon |= S3C2410_IICCON_TXDIV_512;
 661
 662         writel(iiccon, i2c->regs + S3C2410_IICCON);
 663
 664         if (s3c24xx_i2c_is2440(i2c)) {
 665                 unsigned long sda_delay;
 666
 667                 if (pdata->sda_delay) {
 668                         sda_delay = clkin * pdata->sda_delay;
 669                         sda_delay = DIV_ROUND_UP(sda_delay, 1000000);
 670                         sda_delay = DIV_ROUND_UP(sda_delay, 5);
 671                         if (sda_delay > 3)
 672                                 sda_delay = 3;
 673                         sda_delay |= S3C2410_IICLC_FILTER_ON;
 674                 } else
 675                         sda_delay = 0;
 676
 677                 dev_dbg(i2c->dev, "IICLC=%08lx\n", sda_delay);
 678                 writel(sda_delay, i2c->regs + S3C2440_IICLC);
 679         }
 680
 681         return 0;
 682 }
 683
 684 #ifdef CONFIG_CPU_FREQ
 685
 686 #define freq_to_i2c(_n) container_of(_n, struct s3c24xx_i2c, freq_transition)
 687
 688 static int s3c24xx_i2c_cpufreq_transition(struct notifier_block *nb,
 689                                           unsigned long val, void *data)
 690 {
 691         struct s3c24xx_i2c *i2c = freq_to_i2c(nb);
 692         unsigned long flags;
 693         unsigned int got;
 694         int delta_f;
 695         int ret;
 696
 697         delta_f = clk_get_rate(i2c->clk) - i2c->clkrate;
 698
 699         /* if we're post-change and the input clock has slowed down
 700          * or at pre-change and the clock is about to speed up, then
 701          * adjust our clock rate. <0 is slow, >0 speedup.
 702          */
 703
 704         if ((val == CPUFREQ_POSTCHANGE && delta_f < 0) ||
 705             (val == CPUFREQ_PRECHANGE && delta_f > 0)) {
 706                 spin_lock_irqsave(&i2c->lock, flags);
 707                 ret = s3c24xx_i2c_clockrate(i2c, &got);
 708                 spin_unlock_irqrestore(&i2c->lock, flags);
 709
 710                 if (ret < 0)
 711                         dev_err(i2c->dev, "cannot find frequency\n");
 712                 else
 713                         dev_info(i2c->dev, "setting freq %d\n", got);
 714         }
 715
 716         return 0;
 717 }
 718
 719 static inline int s3c24xx_i2c_register_cpufreq(struct s3c24xx_i2c *i2c)
 720 {
 721         i2c->freq_transition.notifier_call = s3c24xx_i2c_cpufreq_transition;
 722
 723         return cpufreq_register_notifier(&i2c->freq_transition,
 724                                          CPUFREQ_TRANSITION_NOTIFIER);
 725 }
 726
 727 static inline void s3c24xx_i2c_deregister_cpufreq(struct s3c24xx_i2c *i2c)
 728 {
 729         cpufreq_unregister_notifier(&i2c->freq_transition,
 730                                     CPUFREQ_TRANSITION_NOTIFIER);
 731 }
 732
 733 #else
 734 static inline int s3c24xx_i2c_register_cpufreq(struct s3c24xx_i2c *i2c)
 735 {
 736         return 0;
 737 }
 738
 739 static inline void s3c24xx_i2c_deregister_cpufreq(struct s3c24xx_i2c *i2c)
 740 {
 741 }
 742 #endif
 743
 744 /* s3c24xx_i2c_init
 745  *
 746  * initialise the controller, set the IO lines and frequency
 747 */
 748
 749 static int s3c24xx_i2c_init(struct s3c24xx_i2c *i2c)
 750 {
 751         unsigned long iicon = S3C2410_IICCON_IRQEN | S3C2410_IICCON_ACKEN;
 752         struct s3c2410_platform_i2c *pdata;
 753         unsigned int freq;
 754
 755         /* get the plafrom data */
 756
 757         pdata = i2c->dev->platform_data;
 758
 759         /* inititalise the gpio */
 760
 761         if (pdata->cfg_gpio)
 762                 pdata->cfg_gpio(to_platform_device(i2c->dev));
 763
 764         /* write slave address */
 765
 766         writeb(pdata->slave_addr, i2c->regs + S3C2410_IICADD);
 767
 768         dev_info(i2c->dev, "slave address 0x%02x\n", pdata->slave_addr);
 769
 770         writel(iicon, i2c->regs + S3C2410_IICCON);
 771
 772         /* we need to work out the divisors for the clock... */
 773
 774         if (s3c24xx_i2c_clockrate(i2c, &freq) != 0) {
 775                 writel(0, i2c->regs + S3C2410_IICCON);
 776                 dev_err(i2c->dev, "cannot meet bus frequency required\n");
 777                 return -EINVAL;
 778         }
 779
 780         /* todo - check that the i2c lines aren't being dragged anywhere */
 781
 782         dev_info(i2c->dev, "bus frequency set to %d KHz\n", freq);
 783         dev_dbg(i2c->dev, "S3C2410_IICCON=0x%02lx\n", iicon);
 784
 785         return 0;
 786 }
 787
 788 /* s3c24xx_i2c_probe
 789  *
 790  * called by the bus driver when a suitable device is found
 791 */
 792
 793 static int s3c24xx_i2c_probe(struct platform_device *pdev)
 794 {
 795         struct s3c24xx_i2c *i2c;
 796         struct s3c2410_platform_i2c *pdata;
 797         struct resource *res;
 798         int ret;
 799
 800         pdata = pdev->dev.platform_data;
 801         if (!pdata) {
 802                 dev_err(&pdev->dev, "no platform data\n");
 803                 return -EINVAL;
 804         }
 805
 806         i2c = kzalloc(sizeof(struct s3c24xx_i2c), GFP_KERNEL);
 807         if (!i2c) {
 808                 dev_err(&pdev->dev, "no memory for state\n");
 809                 return -ENOMEM;
 810         }
 811
 812         strlcpy(i2c->adap.name, "s3c2410-i2c", sizeof(i2c->adap.name));
 813         i2c->adap.owner   = THIS_MODULE;
 814         i2c->adap.algo    = &s3c24xx_i2c_algorithm;
 815         i2c->adap.retries = 2;
 816         i2c->adap.class   = I2C_CLASS_HWMON | I2C_CLASS_SPD;
 817         i2c->tx_setup     = 50;
 818
 819         spin_lock_init(&i2c->lock);
 820         init_waitqueue_head(&i2c->wait);
 821
 822         /* find the clock and enable it */
 823
 824         i2c->dev = &pdev->dev;
 825         i2c->clk = clk_get(&pdev->dev, "i2c");
 826         if (IS_ERR(i2c->clk)) {
 827                 dev_err(&pdev->dev, "cannot get clock\n");
 828                 ret = -ENOENT;
 829                 goto err_noclk;
 830         }
 831
 832         dev_dbg(&pdev->dev, "clock source %p\n", i2c->clk);
 833
 834         clk_enable(i2c->clk);
 835
 836         /* map the registers */
 837
 838         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 839         if (res == NULL) {
 840                 dev_err(&pdev->dev, "cannot find IO resource\n");
 841                 ret = -ENOENT;
 842                 goto err_clk;
 843         }
 844
 845         i2c->ioarea = request_mem_region(res->start, resource_size(res),
 846                                          pdev->name);
 847
 848         if (i2c->ioarea == NULL) {
 849                 dev_err(&pdev->dev, "cannot request IO\n");
 850                 ret = -ENXIO;
 851                 goto err_clk;
 852         }
 853
 854         i2c->regs = ioremap(res->start, resource_size(res));
 855
 856         if (i2c->regs == NULL) {
 857                 dev_err(&pdev->dev, "cannot map IO\n");
 858                 ret = -ENXIO;
 859                 goto err_ioarea;
 860         }
 861
 862         dev_dbg(&pdev->dev, "registers %p (%p, %p)\n",
 863                 i2c->regs, i2c->ioarea, res);
 864
 865         /* setup info block for the i2c core */
 866
 867         i2c->adap.algo_data = i2c;
 868         i2c->adap.dev.parent = &pdev->dev;
 869
 870         /* initialise the i2c controller */
 871
 872         ret = s3c24xx_i2c_init(i2c);
 873         if (ret != 0)
 874                 goto err_iomap;
 875
 876         /* find the IRQ for this unit (note, this relies on the init call to
 877          * ensure no current IRQs pending
 878          */
 879
 880         i2c->irq = ret = platform_get_irq(pdev, 0);
 881         if (ret <= 0) {
 882                 dev_err(&pdev->dev, "cannot find IRQ\n");
 883                 goto err_iomap;
 884         }
 885
 886         ret = request_irq(i2c->irq, s3c24xx_i2c_irq, IRQF_DISABLED,
 887                           dev_name(&pdev->dev), i2c);
 888
 889         if (ret != 0) {
 890                 dev_err(&pdev->dev, "cannot claim IRQ %d\n", i2c->irq);
 891                 goto err_iomap;
 892         }
 893
 894         ret = s3c24xx_i2c_register_cpufreq(i2c);
 895         if (ret < 0) {
 896                 dev_err(&pdev->dev, "failed to register cpufreq notifier\n");
 897                 goto err_irq;
 898         }
 899
 900         /* Note, previous versions of the driver used i2c_add_adapter()
 901          * to add the bus at any number. We now pass the bus number via
 902          * the platform data, so if unset it will now default to always
 903          * being bus 0.
 904          */
 905
 906         i2c->adap.nr = pdata->bus_num;
 907
 908         ret = i2c_add_numbered_adapter(&i2c->adap);
 909         if (ret < 0) {
 910                 dev_err(&pdev->dev, "failed to add bus to i2c core\n");
 911                 goto err_cpufreq;
 912         }
 913
 914         platform_set_drvdata(pdev, i2c);
 915
 916         dev_info(&pdev->dev, "%s: S3C I2C adapter\n", dev_name(&i2c->adap.dev));
 917         clk_disable(i2c->clk);
 918         return 0;
 919
 920  err_cpufreq:
 921         s3c24xx_i2c_deregister_cpufreq(i2c);
 922
 923  err_irq:
 924         free_irq(i2c->irq, i2c);
 925
 926  err_iomap:
 927         iounmap(i2c->regs);
 928
 929  err_ioarea:
 930         release_resource(i2c->ioarea);
 931         kfree(i2c->ioarea);
 932
 933  err_clk:
 934         clk_disable(i2c->clk);
 935         clk_put(i2c->clk);
 936
 937  err_noclk:
 938         kfree(i2c);
 939         return ret;
 940 }
 941
 942 /* s3c24xx_i2c_remove
 943  *
 944  * called when device is removed from the bus
 945 */
 946
 947 static int s3c24xx_i2c_remove(struct platform_device *pdev)
 948 {
 949         struct s3c24xx_i2c *i2c = platform_get_drvdata(pdev);
 950
 951         s3c24xx_i2c_deregister_cpufreq(i2c);
 952
 953         i2c_del_adapter(&i2c->adap);
 954         free_irq(i2c->irq, i2c);
 955
 956         clk_disable(i2c->clk);
 957         clk_put(i2c->clk);
 958
 959         iounmap(i2c->regs);
 960
 961         release_resource(i2c->ioarea);
 962         kfree(i2c->ioarea);
 963         kfree(i2c);
 964
 965         return 0;
 966 }
 967
 968 #ifdef CONFIG_PM
 969 static int s3c24xx_i2c_suspend_noirq(struct device *dev)
 970 {
 971         struct platform_device *pdev = to_platform_device(dev);
 972         struct s3c24xx_i2c *i2c = platform_get_drvdata(pdev);
 973
 974         i2c->suspended = 1;
 975
 976         return 0;
 977 }
 978
 979 static int s3c24xx_i2c_resume(struct device *dev)
 980 {
 981         struct platform_device *pdev = to_platform_device(dev);
 982         struct s3c24xx_i2c *i2c = platform_get_drvdata(pdev);
 983
 984         i2c->suspended = 0;
 985         clk_enable(i2c->clk);
 986         s3c24xx_i2c_init(i2c);
 987         clk_disable(i2c->clk);
 988
 989         return 0;
 990 }
 991
 992 static const struct dev_pm_ops s3c24xx_i2c_dev_pm_ops = {
 993         .suspend_noirq = s3c24xx_i2c_suspend_noirq,
 994         .resume = s3c24xx_i2c_resume,
 995 };
 996
 997 #define S3C24XX_DEV_PM_OPS (&s3c24xx_i2c_dev_pm_ops)
 998 #else
 999 #define S3C24XX_DEV_PM_OPS NULL
1000 #endif
1001
1002 /* device driver for platform bus bits */
1003
1004 static struct platform_device_id s3c24xx_driver_ids[] = {
1005         {
1006                 .name           = "s3c2410-i2c",
1007                 .driver_data    = TYPE_S3C2410,
1008         }, {
1009                 .name           = "s3c2440-i2c",
1010                 .driver_data    = TYPE_S3C2440,
1011         }, { },
1012 };
1013 MODULE_DEVICE_TABLE(platform, s3c24xx_driver_ids);
1014
1015 static struct platform_driver s3c24xx_i2c_driver = {
1016         .probe          = s3c24xx_i2c_probe,
1017         .remove         = s3c24xx_i2c_remove,
1018         .id_table       = s3c24xx_driver_ids,
1019         .driver         = {
1020                 .owner  = THIS_MODULE,
1021                 .name   = "s3c-i2c",
1022                 .pm     = S3C24XX_DEV_PM_OPS,
1023         },
1024 };
1025
1026 static int __init i2c_adap_s3c_init(void)
1027 {
1028         return platform_driver_register(&s3c24xx_i2c_driver);
1029 }
1030 subsys_initcall(i2c_adap_s3c_init);
1031
1032 static void __exit i2c_adap_s3c_exit(void)
1033 {
1034         platform_driver_unregister(&s3c24xx_i2c_driver);
1035 }
1036 module_exit(i2c_adap_s3c_exit);
1037
1038 MODULE_DESCRIPTION("S3C24XX I2C Bus driver");
1039 MODULE_AUTHOR("Ben Dooks, <ben@simtec.co.uk>");
1040 MODULE_LICENSE("GPL");