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/pm_runtime.h>
  35 #include <linux/clk.h>
  36 #include <linux/cpufreq.h>
  37 #include <linux/slab.h>
  38 #include <linux/io.h>
  39 #include <linux/of_i2c.h>
  40 #include <linux/of_gpio.h>
  41 #include <linux/pinctrl/consumer.h>
  42
  43 #include <asm/irq.h>
  44
  45 #include <linux/platform_data/i2c-s3c2410.h>
  46
  47 /* see s3c2410x user guide, v1.1, section 9 (p447) for more info */
  48
  49 #define S3C2410_IICCON                  0x00
  50 #define S3C2410_IICSTAT                 0x04
  51 #define S3C2410_IICADD                  0x08
  52 #define S3C2410_IICDS                   0x0C
  53 #define S3C2440_IICLC                   0x10
  54
  55 #define S3C2410_IICCON_ACKEN            (1 << 7)
  56 #define S3C2410_IICCON_TXDIV_16         (0 << 6)
  57 #define S3C2410_IICCON_TXDIV_512        (1 << 6)
  58 #define S3C2410_IICCON_IRQEN            (1 << 5)
  59 #define S3C2410_IICCON_IRQPEND          (1 << 4)
  60 #define S3C2410_IICCON_SCALE(x)         ((x) & 0xf)
  61 #define S3C2410_IICCON_SCALEMASK        (0xf)
  62
  63 #define S3C2410_IICSTAT_MASTER_RX       (2 << 6)
  64 #define S3C2410_IICSTAT_MASTER_TX       (3 << 6)
  65 #define S3C2410_IICSTAT_SLAVE_RX        (0 << 6)
  66 #define S3C2410_IICSTAT_SLAVE_TX        (1 << 6)
  67 #define S3C2410_IICSTAT_MODEMASK        (3 << 6)
  68
  69 #define S3C2410_IICSTAT_START           (1 << 5)
  70 #define S3C2410_IICSTAT_BUSBUSY         (1 << 5)
  71 #define S3C2410_IICSTAT_TXRXEN          (1 << 4)
  72 #define S3C2410_IICSTAT_ARBITR          (1 << 3)
  73 #define S3C2410_IICSTAT_ASSLAVE         (1 << 2)
  74 #define S3C2410_IICSTAT_ADDR0           (1 << 1)
  75 #define S3C2410_IICSTAT_LASTBIT         (1 << 0)
  76
  77 #define S3C2410_IICLC_SDA_DELAY0        (0 << 0)
  78 #define S3C2410_IICLC_SDA_DELAY5        (1 << 0)
  79 #define S3C2410_IICLC_SDA_DELAY10       (2 << 0)
  80 #define S3C2410_IICLC_SDA_DELAY15       (3 << 0)
  81 #define S3C2410_IICLC_SDA_DELAY_MASK    (3 << 0)
  82
  83 #define S3C2410_IICLC_FILTER_ON         (1 << 2)
  84
  85 /* Treat S3C2410 as baseline hardware, anything else is supported via quirks */
  86 #define QUIRK_S3C2440           (1 << 0)
  87 #define QUIRK_HDMIPHY           (1 << 1)
  88 #define QUIRK_NO_GPIO           (1 << 2)
  89
  90 /* Max time to wait for bus to become idle after a xfer (in us) */
  91 #define S3C2410_IDLE_TIMEOUT    5000
  92
  93 /* i2c controller state */
  94 enum s3c24xx_i2c_state {
  95         STATE_IDLE,
  96         STATE_START,
  97         STATE_READ,
  98         STATE_WRITE,
  99         STATE_STOP
 100 };
 101
 102 struct s3c24xx_i2c {
 103         wait_queue_head_t       wait;
 104         unsigned int            quirks;
 105         unsigned int            suspended:1;
 106
 107         struct i2c_msg          *msg;
 108         unsigned int            msg_num;
 109         unsigned int            msg_idx;
 110         unsigned int            msg_ptr;
 111
 112         unsigned int            tx_setup;
 113         unsigned int            irq;
 114
 115         enum s3c24xx_i2c_state  state;
 116         unsigned long           clkrate;
 117
 118         void __iomem            *regs;
 119         struct clk              *clk;
 120         struct device           *dev;
 121         struct i2c_adapter      adap;
 122
 123         struct s3c2410_platform_i2c     *pdata;
 124         int                     gpios[2];
 125         struct pinctrl          *pctrl;
 126 #ifdef CONFIG_CPU_FREQ
 127         struct notifier_block   freq_transition;
 128 #endif
 129 };
 130
 131 static struct platform_device_id s3c24xx_driver_ids[] = {
 132         {
 133                 .name           = "s3c2410-i2c",
 134                 .driver_data    = 0,
 135         }, {
 136                 .name           = "s3c2440-i2c",
 137                 .driver_data    = QUIRK_S3C2440,
 138         }, {
 139                 .name           = "s3c2440-hdmiphy-i2c",
 140                 .driver_data    = QUIRK_S3C2440 | QUIRK_HDMIPHY | QUIRK_NO_GPIO,
 141         }, { },
 142 };
 143 MODULE_DEVICE_TABLE(platform, s3c24xx_driver_ids);
 144
 145 #ifdef CONFIG_OF
 146 static const struct of_device_id s3c24xx_i2c_match[] = {
 147         { .compatible = "samsung,s3c2410-i2c", .data = (void *)0 },
 148         { .compatible = "samsung,s3c2440-i2c", .data = (void *)QUIRK_S3C2440 },
 149         { .compatible = "samsung,s3c2440-hdmiphy-i2c",
 150           .data = (void *)(QUIRK_S3C2440 | QUIRK_HDMIPHY | QUIRK_NO_GPIO) },
 151         { .compatible = "samsung,exynos5440-i2c",
 152           .data = (void *)(QUIRK_S3C2440 | QUIRK_NO_GPIO) },
 153         {},
 154 };
 155 MODULE_DEVICE_TABLE(of, s3c24xx_i2c_match);
 156 #endif
 157
 158 /* s3c24xx_get_device_quirks
 159  *
 160  * Get controller type either from device tree or platform device variant.
 161 */
 162
 163 static inline unsigned int s3c24xx_get_device_quirks(struct platform_device *pdev)
 164 {
 165         if (pdev->dev.of_node) {
 166                 const struct of_device_id *match;
 167                 match = of_match_node(s3c24xx_i2c_match, pdev->dev.of_node);
 168                 return (unsigned int)match->data;
 169         }
 170
 171         return platform_get_device_id(pdev)->driver_data;
 172 }
 173
 174 /* s3c24xx_i2c_master_complete
 175  *
 176  * complete the message and wake up the caller, using the given return code,
 177  * or zero to mean ok.
 178 */
 179
 180 static inline void s3c24xx_i2c_master_complete(struct s3c24xx_i2c *i2c, int ret)
 181 {
 182         dev_dbg(i2c->dev, "master_complete %d\n", ret);
 183
 184         i2c->msg_ptr = 0;
 185         i2c->msg = NULL;
 186         i2c->msg_idx++;
 187         i2c->msg_num = 0;
 188         if (ret)
 189                 i2c->msg_idx = ret;
 190
 191         wake_up(&i2c->wait);
 192 }
 193
 194 static inline void s3c24xx_i2c_disable_ack(struct s3c24xx_i2c *i2c)
 195 {
 196         unsigned long tmp;
 197
 198         tmp = readl(i2c->regs + S3C2410_IICCON);
 199         writel(tmp & ~S3C2410_IICCON_ACKEN, i2c->regs + S3C2410_IICCON);
 200 }
 201
 202 static inline void s3c24xx_i2c_enable_ack(struct s3c24xx_i2c *i2c)
 203 {
 204         unsigned long tmp;
 205
 206         tmp = readl(i2c->regs + S3C2410_IICCON);
 207         writel(tmp | S3C2410_IICCON_ACKEN, i2c->regs + S3C2410_IICCON);
 208 }
 209
 210 /* irq enable/disable functions */
 211
 212 static inline void s3c24xx_i2c_disable_irq(struct s3c24xx_i2c *i2c)
 213 {
 214         unsigned long tmp;
 215
 216         tmp = readl(i2c->regs + S3C2410_IICCON);
 217         writel(tmp & ~S3C2410_IICCON_IRQEN, i2c->regs + S3C2410_IICCON);
 218 }
 219
 220 static inline void s3c24xx_i2c_enable_irq(struct s3c24xx_i2c *i2c)
 221 {
 222         unsigned long tmp;
 223
 224         tmp = readl(i2c->regs + S3C2410_IICCON);
 225         writel(tmp | S3C2410_IICCON_IRQEN, i2c->regs + S3C2410_IICCON);
 226 }
 227
 228
 229 /* s3c24xx_i2c_message_start
 230  *
 231  * put the start of a message onto the bus
 232 */
 233
 234 static void s3c24xx_i2c_message_start(struct s3c24xx_i2c *i2c,
 235                                       struct i2c_msg *msg)
 236 {
 237         unsigned int addr = (msg->addr & 0x7f) << 1;
 238         unsigned long stat;
 239         unsigned long iiccon;
 240
 241         stat = 0;
 242         stat |=  S3C2410_IICSTAT_TXRXEN;
 243
 244         if (msg->flags & I2C_M_RD) {
 245                 stat |= S3C2410_IICSTAT_MASTER_RX;
 246                 addr |= 1;
 247         } else
 248                 stat |= S3C2410_IICSTAT_MASTER_TX;
 249
 250         if (msg->flags & I2C_M_REV_DIR_ADDR)
 251                 addr ^= 1;
 252
 253         /* todo - check for whether ack wanted or not */
 254         s3c24xx_i2c_enable_ack(i2c);
 255
 256         iiccon = readl(i2c->regs + S3C2410_IICCON);
 257         writel(stat, i2c->regs + S3C2410_IICSTAT);
 258
 259         dev_dbg(i2c->dev, "START: %08lx to IICSTAT, %02x to DS\n", stat, addr);
 260         writeb(addr, i2c->regs + S3C2410_IICDS);
 261
 262         /* delay here to ensure the data byte has gotten onto the bus
 263          * before the transaction is started */
 264
 265         ndelay(i2c->tx_setup);
 266
 267         dev_dbg(i2c->dev, "iiccon, %08lx\n", iiccon);
 268         writel(iiccon, i2c->regs + S3C2410_IICCON);
 269
 270         stat |= S3C2410_IICSTAT_START;
 271         writel(stat, i2c->regs + S3C2410_IICSTAT);
 272 }
 273
 274 static inline void s3c24xx_i2c_stop(struct s3c24xx_i2c *i2c, int ret)
 275 {
 276         unsigned long iicstat = readl(i2c->regs + S3C2410_IICSTAT);
 277
 278         dev_dbg(i2c->dev, "STOP\n");
 279
 280         /*
 281          * The datasheet says that the STOP sequence should be:
 282          *  1) I2CSTAT.5 = 0    - Clear BUSY (or 'generate STOP')
 283          *  2) I2CCON.4 = 0     - Clear IRQPEND
 284          *  3) Wait until the stop condition takes effect.
 285          *  4*) I2CSTAT.4 = 0   - Clear TXRXEN
 286          *
 287          * Where, step "4*" is only for buses with the "HDMIPHY" quirk.
 288          *
 289          * However, after much experimentation, it appears that:
 290          * a) normal buses automatically clear BUSY and transition from
 291          *    Master->Slave when they complete generating a STOP condition.
 292          *    Therefore, step (3) can be done in doxfer() by polling I2CCON.4
 293          *    after starting the STOP generation here.
 294          * b) HDMIPHY bus does neither, so there is no way to do step 3.
 295          *    There is no indication when this bus has finished generating
 296          *    STOP.
 297          *
 298          * In fact, we have found that as soon as the IRQPEND bit is cleared in
 299          * step 2, the HDMIPHY bus generates the STOP condition, and then
 300          * immediately starts transferring another data byte, even though the
 301          * bus is supposedly stopped.  This is presumably because the bus is
 302          * still in "Master" mode, and its BUSY bit is still set.
 303          *
 304          * To avoid these extra post-STOP transactions on HDMI phy devices, we
 305          * just disable Serial Output on the bus (I2CSTAT.4 = 0) directly,
 306          * instead of first generating a proper STOP condition.  This should
 307          * float SDA & SCK terminating the transfer.  Subsequent transfers
 308          *  start with a proper START condition, and proceed normally.
 309          *
 310          * The HDMIPHY bus is an internal bus that always has exactly two
 311          * devices, the host as Master and the HDMIPHY device as the slave.
 312          * Skipping the STOP condition has been tested on this bus and works.
 313          */
 314         if (i2c->quirks & QUIRK_HDMIPHY) {
 315                 /* Stop driving the I2C pins */
 316                 iicstat &= ~S3C2410_IICSTAT_TXRXEN;
 317         } else {
 318                 /* stop the transfer */
 319                 iicstat &= ~S3C2410_IICSTAT_START;
 320         }
 321         writel(iicstat, i2c->regs + S3C2410_IICSTAT);
 322
 323         i2c->state = STATE_STOP;
 324
 325         s3c24xx_i2c_master_complete(i2c, ret);
 326         s3c24xx_i2c_disable_irq(i2c);
 327 }
 328
 329 /* helper functions to determine the current state in the set of
 330  * messages we are sending */
 331
 332 /* is_lastmsg()
 333  *
 334  * returns TRUE if the current message is the last in the set
 335 */
 336
 337 static inline int is_lastmsg(struct s3c24xx_i2c *i2c)
 338 {
 339         return i2c->msg_idx >= (i2c->msg_num - 1);
 340 }
 341
 342 /* is_msglast
 343  *
 344  * returns TRUE if we this is the last byte in the current message
 345 */
 346
 347 static inline int is_msglast(struct s3c24xx_i2c *i2c)
 348 {
 349         /* msg->len is always 1 for the first byte of smbus block read.
 350          * Actual length will be read from slave. More bytes will be
 351          * read according to the length then. */
 352         if (i2c->msg->flags & I2C_M_RECV_LEN && i2c->msg->len == 1)
 353                 return 0;
 354
 355         return i2c->msg_ptr == i2c->msg->len-1;
 356 }
 357
 358 /* is_msgend
 359  *
 360  * returns TRUE if we reached the end of the current message
 361 */
 362
 363 static inline int is_msgend(struct s3c24xx_i2c *i2c)
 364 {
 365         return i2c->msg_ptr >= i2c->msg->len;
 366 }
 367
 368 /* i2c_s3c_irq_nextbyte
 369  *
 370  * process an interrupt and work out what to do
 371  */
 372
 373 static int i2c_s3c_irq_nextbyte(struct s3c24xx_i2c *i2c, unsigned long iicstat)
 374 {
 375         unsigned long tmp;
 376         unsigned char byte;
 377         int ret = 0;
 378
 379         switch (i2c->state) {
 380
 381         case STATE_IDLE:
 382                 dev_err(i2c->dev, "%s: called in STATE_IDLE\n", __func__);
 383                 goto out;
 384
 385         case STATE_STOP:
 386                 dev_err(i2c->dev, "%s: called in STATE_STOP\n", __func__);
 387                 s3c24xx_i2c_disable_irq(i2c);
 388                 goto out_ack;
 389
 390         case STATE_START:
 391                 /* last thing we did was send a start condition on the
 392                  * bus, or started a new i2c message
 393                  */
 394
 395                 if (iicstat & S3C2410_IICSTAT_LASTBIT &&
 396                     !(i2c->msg->flags & I2C_M_IGNORE_NAK)) {
 397                         /* ack was not received... */
 398
 399                         dev_dbg(i2c->dev, "ack was not received\n");
 400                         s3c24xx_i2c_stop(i2c, -ENXIO);
 401                         goto out_ack;
 402                 }
 403
 404                 if (i2c->msg->flags & I2C_M_RD)
 405                         i2c->state = STATE_READ;
 406                 else
 407                         i2c->state = STATE_WRITE;
 408
 409                 /* terminate the transfer if there is nothing to do
 410                  * as this is used by the i2c probe to find devices. */
 411
 412                 if (is_lastmsg(i2c) && i2c->msg->len == 0) {
 413                         s3c24xx_i2c_stop(i2c, 0);
 414                         goto out_ack;
 415                 }
 416
 417                 if (i2c->state == STATE_READ)
 418                         goto prepare_read;
 419
 420                 /* fall through to the write state, as we will need to
 421                  * send a byte as well */
 422
 423         case STATE_WRITE:
 424                 /* we are writing data to the device... check for the
 425                  * end of the message, and if so, work out what to do
 426                  */
 427
 428                 if (!(i2c->msg->flags & I2C_M_IGNORE_NAK)) {
 429                         if (iicstat & S3C2410_IICSTAT_LASTBIT) {
 430                                 dev_dbg(i2c->dev, "WRITE: No Ack\n");
 431
 432                                 s3c24xx_i2c_stop(i2c, -ECONNREFUSED);
 433                                 goto out_ack;
 434                         }
 435                 }
 436
 437  retry_write:
 438
 439                 if (!is_msgend(i2c)) {
 440                         byte = i2c->msg->buf[i2c->msg_ptr++];
 441                         writeb(byte, i2c->regs + S3C2410_IICDS);
 442
 443                         /* delay after writing the byte to allow the
 444                          * data setup time on the bus, as writing the
 445                          * data to the register causes the first bit
 446                          * to appear on SDA, and SCL will change as
 447                          * soon as the interrupt is acknowledged */
 448
 449                         ndelay(i2c->tx_setup);
 450
 451                 } else if (!is_lastmsg(i2c)) {
 452                         /* we need to go to the next i2c message */
 453
 454                         dev_dbg(i2c->dev, "WRITE: Next Message\n");
 455
 456                         i2c->msg_ptr = 0;
 457                         i2c->msg_idx++;
 458                         i2c->msg++;
 459
 460                         /* check to see if we need to do another message */
 461                         if (i2c->msg->flags & I2C_M_NOSTART) {
 462
 463                                 if (i2c->msg->flags & I2C_M_RD) {
 464                                         /* cannot do this, the controller
 465                                          * forces us to send a new START
 466                                          * when we change direction */
 467
 468                                         s3c24xx_i2c_stop(i2c, -EINVAL);
 469                                 }
 470
 471                                 goto retry_write;
 472                         } else {
 473                                 /* send the new start */
 474                                 s3c24xx_i2c_message_start(i2c, i2c->msg);
 475                                 i2c->state = STATE_START;
 476                         }
 477
 478                 } else {
 479                         /* send stop */
 480
 481                         s3c24xx_i2c_stop(i2c, 0);
 482                 }
 483                 break;
 484
 485         case STATE_READ:
 486                 /* we have a byte of data in the data register, do
 487                  * something with it, and then work out whether we are
 488                  * going to do any more read/write
 489                  */
 490
 491                 byte = readb(i2c->regs + S3C2410_IICDS);
 492                 i2c->msg->buf[i2c->msg_ptr++] = byte;
 493
 494                 /* Add actual length to read for smbus block read */
 495                 if (i2c->msg->flags & I2C_M_RECV_LEN && i2c->msg->len == 1)
 496                         i2c->msg->len += byte;
 497  prepare_read:
 498                 if (is_msglast(i2c)) {
 499                         /* last byte of buffer */
 500
 501                         if (is_lastmsg(i2c))
 502                                 s3c24xx_i2c_disable_ack(i2c);
 503
 504                 } else if (is_msgend(i2c)) {
 505                         /* ok, we've read the entire buffer, see if there
 506                          * is anything else we need to do */
 507
 508                         if (is_lastmsg(i2c)) {
 509                                 /* last message, send stop and complete */
 510                                 dev_dbg(i2c->dev, "READ: Send Stop\n");
 511
 512                                 s3c24xx_i2c_stop(i2c, 0);
 513                         } else {
 514                                 /* go to the next transfer */
 515                                 dev_dbg(i2c->dev, "READ: Next Transfer\n");
 516
 517                                 i2c->msg_ptr = 0;
 518                                 i2c->msg_idx++;
 519                                 i2c->msg++;
 520                         }
 521                 }
 522
 523                 break;
 524         }
 525
 526         /* acknowlegde the IRQ and get back on with the work */
 527
 528  out_ack:
 529         tmp = readl(i2c->regs + S3C2410_IICCON);
 530         tmp &= ~S3C2410_IICCON_IRQPEND;
 531         writel(tmp, i2c->regs + S3C2410_IICCON);
 532  out:
 533         return ret;
 534 }
 535
 536 /* s3c24xx_i2c_irq
 537  *
 538  * top level IRQ servicing routine
 539 */
 540
 541 static irqreturn_t s3c24xx_i2c_irq(int irqno, void *dev_id)
 542 {
 543         struct s3c24xx_i2c *i2c = dev_id;
 544         unsigned long status;
 545         unsigned long tmp;
 546
 547         status = readl(i2c->regs + S3C2410_IICSTAT);
 548
 549         if (status & S3C2410_IICSTAT_ARBITR) {
 550                 /* deal with arbitration loss */
 551                 dev_err(i2c->dev, "deal with arbitration loss\n");
 552         }
 553
 554         if (i2c->state == STATE_IDLE) {
 555                 dev_dbg(i2c->dev, "IRQ: error i2c->state == IDLE\n");
 556
 557                 tmp = readl(i2c->regs + S3C2410_IICCON);
 558                 tmp &= ~S3C2410_IICCON_IRQPEND;
 559                 writel(tmp, i2c->regs +  S3C2410_IICCON);
 560                 goto out;
 561         }
 562
 563         /* pretty much this leaves us with the fact that we've
 564          * transmitted or received whatever byte we last sent */
 565
 566         i2c_s3c_irq_nextbyte(i2c, status);
 567
 568  out:
 569         return IRQ_HANDLED;
 570 }
 571
 572
 573 /* s3c24xx_i2c_set_master
 574  *
 575  * get the i2c bus for a master transaction
 576 */
 577
 578 static int s3c24xx_i2c_set_master(struct s3c24xx_i2c *i2c)
 579 {
 580         unsigned long iicstat;
 581         int timeout = 400;
 582
 583         while (timeout-- > 0) {
 584                 iicstat = readl(i2c->regs + S3C2410_IICSTAT);
 585
 586                 if (!(iicstat & S3C2410_IICSTAT_BUSBUSY))
 587                         return 0;
 588
 589                 msleep(1);
 590         }
 591
 592         return -ETIMEDOUT;
 593 }
 594
 595 /* s3c24xx_i2c_wait_idle
 596  *
 597  * wait for the i2c bus to become idle.
 598 */
 599
 600 static void s3c24xx_i2c_wait_idle(struct s3c24xx_i2c *i2c)
 601 {
 602         unsigned long iicstat;
 603         ktime_t start, now;
 604         unsigned long delay;
 605         int spins;
 606
 607         /* ensure the stop has been through the bus */
 608
 609         dev_dbg(i2c->dev, "waiting for bus idle\n");
 610
 611         start = now = ktime_get();
 612
 613         /*
 614          * Most of the time, the bus is already idle within a few usec of the
 615          * end of a transaction.  However, really slow i2c devices can stretch
 616          * the clock, delaying STOP generation.
 617          *
 618          * On slower SoCs this typically happens within a very small number of
 619          * instructions so busy wait briefly to avoid scheduling overhead.
 620          */
 621         spins = 3;
 622         iicstat = readl(i2c->regs + S3C2410_IICSTAT);
 623         while ((iicstat & S3C2410_IICSTAT_START) && --spins) {
 624                 cpu_relax();
 625                 iicstat = readl(i2c->regs + S3C2410_IICSTAT);
 626         }
 627
 628         /*
 629          * If we do get an appreciable delay as a compromise between idle
 630          * detection latency for the normal, fast case, and system load in the
 631          * slow device case, use an exponential back off in the polling loop,
 632          * up to 1/10th of the total timeout, then continue to poll at a
 633          * constant rate up to the timeout.
 634          */
 635         delay = 1;
 636         while ((iicstat & S3C2410_IICSTAT_START) &&
 637                ktime_us_delta(now, start) < S3C2410_IDLE_TIMEOUT) {
 638                 usleep_range(delay, 2 * delay);
 639                 if (delay < S3C2410_IDLE_TIMEOUT / 10)
 640                         delay <<= 1;
 641                 now = ktime_get();
 642                 iicstat = readl(i2c->regs + S3C2410_IICSTAT);
 643         }
 644
 645         if (iicstat & S3C2410_IICSTAT_START)
 646                 dev_warn(i2c->dev, "timeout waiting for bus idle\n");
 647 }
 648
 649 /* s3c24xx_i2c_doxfer
 650  *
 651  * this starts an i2c transfer
 652 */
 653
 654 static int s3c24xx_i2c_doxfer(struct s3c24xx_i2c *i2c,
 655                               struct i2c_msg *msgs, int num)
 656 {
 657         unsigned long timeout;
 658         int ret;
 659
 660         if (i2c->suspended)
 661                 return -EIO;
 662
 663         ret = s3c24xx_i2c_set_master(i2c);
 664         if (ret != 0) {
 665                 dev_err(i2c->dev, "cannot get bus (error %d)\n", ret);
 666                 ret = -EAGAIN;
 667                 goto out;
 668         }
 669
 670         i2c->msg     = msgs;
 671         i2c->msg_num = num;
 672         i2c->msg_ptr = 0;
 673         i2c->msg_idx = 0;
 674         i2c->state   = STATE_START;
 675
 676         s3c24xx_i2c_enable_irq(i2c);
 677         s3c24xx_i2c_message_start(i2c, msgs);
 678
 679         timeout = wait_event_timeout(i2c->wait, i2c->msg_num == 0, HZ * 5);
 680
 681         ret = i2c->msg_idx;
 682
 683         /* having these next two as dev_err() makes life very
 684          * noisy when doing an i2cdetect */
 685
 686         if (timeout == 0)
 687                 dev_dbg(i2c->dev, "timeout\n");
 688         else if (ret != num)
 689                 dev_dbg(i2c->dev, "incomplete xfer (%d)\n", ret);
 690
 691         /* For QUIRK_HDMIPHY, bus is already disabled */
 692         if (i2c->quirks & QUIRK_HDMIPHY)
 693                 goto out;
 694
 695         s3c24xx_i2c_wait_idle(i2c);
 696
 697  out:
 698         return ret;
 699 }
 700
 701 /* s3c24xx_i2c_xfer
 702  *
 703  * first port of call from the i2c bus code when an message needs
 704  * transferring across the i2c bus.
 705 */
 706
 707 static int s3c24xx_i2c_xfer(struct i2c_adapter *adap,
 708                         struct i2c_msg *msgs, int num)
 709 {
 710         struct s3c24xx_i2c *i2c = (struct s3c24xx_i2c *)adap->algo_data;
 711         int retry;
 712         int ret;
 713
 714         pm_runtime_get_sync(&adap->dev);
 715         clk_prepare_enable(i2c->clk);
 716
 717         for (retry = 0; retry < adap->retries; retry++) {
 718
 719                 ret = s3c24xx_i2c_doxfer(i2c, msgs, num);
 720
 721                 if (ret != -EAGAIN) {
 722                         clk_disable_unprepare(i2c->clk);
 723                         pm_runtime_put(&adap->dev);
 724                         return ret;
 725                 }
 726
 727                 dev_dbg(i2c->dev, "Retrying transmission (%d)\n", retry);
 728
 729                 udelay(100);
 730         }
 731
 732         clk_disable_unprepare(i2c->clk);
 733         pm_runtime_put(&adap->dev);
 734         return -EREMOTEIO;
 735 }
 736
 737 /* declare our i2c functionality */
 738 static u32 s3c24xx_i2c_func(struct i2c_adapter *adap)
 739 {
 740         return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_NOSTART |
 741                 I2C_FUNC_PROTOCOL_MANGLING;
 742 }
 743
 744 /* i2c bus registration info */
 745
 746 static const struct i2c_algorithm s3c24xx_i2c_algorithm = {
 747         .master_xfer            = s3c24xx_i2c_xfer,
 748         .functionality          = s3c24xx_i2c_func,
 749 };
 750
 751 /* s3c24xx_i2c_calcdivisor
 752  *
 753  * return the divisor settings for a given frequency
 754 */
 755
 756 static int s3c24xx_i2c_calcdivisor(unsigned long clkin, unsigned int wanted,
 757                                    unsigned int *div1, unsigned int *divs)
 758 {
 759         unsigned int calc_divs = clkin / wanted;
 760         unsigned int calc_div1;
 761
 762         if (calc_divs > (16*16))
 763                 calc_div1 = 512;
 764         else
 765                 calc_div1 = 16;
 766
 767         calc_divs += calc_div1-1;
 768         calc_divs /= calc_div1;
 769
 770         if (calc_divs == 0)
 771                 calc_divs = 1;
 772         if (calc_divs > 17)
 773                 calc_divs = 17;
 774
 775         *divs = calc_divs;
 776         *div1 = calc_div1;
 777
 778         return clkin / (calc_divs * calc_div1);
 779 }
 780
 781 /* s3c24xx_i2c_clockrate
 782  *
 783  * work out a divisor for the user requested frequency setting,
 784  * either by the requested frequency, or scanning the acceptable
 785  * range of frequencies until something is found
 786 */
 787
 788 static int s3c24xx_i2c_clockrate(struct s3c24xx_i2c *i2c, unsigned int *got)
 789 {
 790         struct s3c2410_platform_i2c *pdata = i2c->pdata;
 791         unsigned long clkin = clk_get_rate(i2c->clk);
 792         unsigned int divs, div1;
 793         unsigned long target_frequency;
 794         u32 iiccon;
 795         int freq;
 796
 797         i2c->clkrate = clkin;
 798         clkin /= 1000;          /* clkin now in KHz */
 799
 800         dev_dbg(i2c->dev, "pdata desired frequency %lu\n", pdata->frequency);
 801
 802         target_frequency = pdata->frequency ? pdata->frequency : 100000;
 803
 804         target_frequency /= 1000; /* Target frequency now in KHz */
 805
 806         freq = s3c24xx_i2c_calcdivisor(clkin, target_frequency, &div1, &divs);
 807
 808         if (freq > target_frequency) {
 809                 dev_err(i2c->dev,
 810                         "Unable to achieve desired frequency %luKHz."   \
 811                         " Lowest achievable %dKHz\n", target_frequency, freq);
 812                 return -EINVAL;
 813         }
 814
 815         *got = freq;
 816
 817         iiccon = readl(i2c->regs + S3C2410_IICCON);
 818         iiccon &= ~(S3C2410_IICCON_SCALEMASK | S3C2410_IICCON_TXDIV_512);
 819         iiccon |= (divs-1);
 820
 821         if (div1 == 512)
 822                 iiccon |= S3C2410_IICCON_TXDIV_512;
 823
 824         writel(iiccon, i2c->regs + S3C2410_IICCON);
 825
 826         if (i2c->quirks & QUIRK_S3C2440) {
 827                 unsigned long sda_delay;
 828
 829                 if (pdata->sda_delay) {
 830                         sda_delay = clkin * pdata->sda_delay;
 831                         sda_delay = DIV_ROUND_UP(sda_delay, 1000000);
 832                         sda_delay = DIV_ROUND_UP(sda_delay, 5);
 833                         if (sda_delay > 3)
 834                                 sda_delay = 3;
 835                         sda_delay |= S3C2410_IICLC_FILTER_ON;
 836                 } else
 837                         sda_delay = 0;
 838
 839                 dev_dbg(i2c->dev, "IICLC=%08lx\n", sda_delay);
 840                 writel(sda_delay, i2c->regs + S3C2440_IICLC);
 841         }
 842
 843         return 0;
 844 }
 845
 846 #ifdef CONFIG_CPU_FREQ
 847
 848 #define freq_to_i2c(_n) container_of(_n, struct s3c24xx_i2c, freq_transition)
 849
 850 static int s3c24xx_i2c_cpufreq_transition(struct notifier_block *nb,
 851                                           unsigned long val, void *data)
 852 {
 853         struct s3c24xx_i2c *i2c = freq_to_i2c(nb);
 854         unsigned int got;
 855         int delta_f;
 856         int ret;
 857
 858         delta_f = clk_get_rate(i2c->clk) - i2c->clkrate;
 859
 860         /* if we're post-change and the input clock has slowed down
 861          * or at pre-change and the clock is about to speed up, then
 862          * adjust our clock rate. <0 is slow, >0 speedup.
 863          */
 864
 865         if ((val == CPUFREQ_POSTCHANGE && delta_f < 0) ||
 866             (val == CPUFREQ_PRECHANGE && delta_f > 0)) {
 867                 i2c_lock_adapter(&i2c->adap);
 868                 ret = s3c24xx_i2c_clockrate(i2c, &got);
 869                 i2c_unlock_adapter(&i2c->adap);
 870
 871                 if (ret < 0)
 872                         dev_err(i2c->dev, "cannot find frequency\n");
 873                 else
 874                         dev_info(i2c->dev, "setting freq %d\n", got);
 875         }
 876
 877         return 0;
 878 }
 879
 880 static inline int s3c24xx_i2c_register_cpufreq(struct s3c24xx_i2c *i2c)
 881 {
 882         i2c->freq_transition.notifier_call = s3c24xx_i2c_cpufreq_transition;
 883
 884         return cpufreq_register_notifier(&i2c->freq_transition,
 885                                          CPUFREQ_TRANSITION_NOTIFIER);
 886 }
 887
 888 static inline void s3c24xx_i2c_deregister_cpufreq(struct s3c24xx_i2c *i2c)
 889 {
 890         cpufreq_unregister_notifier(&i2c->freq_transition,
 891                                     CPUFREQ_TRANSITION_NOTIFIER);
 892 }
 893
 894 #else
 895 static inline int s3c24xx_i2c_register_cpufreq(struct s3c24xx_i2c *i2c)
 896 {
 897         return 0;
 898 }
 899
 900 static inline void s3c24xx_i2c_deregister_cpufreq(struct s3c24xx_i2c *i2c)
 901 {
 902 }
 903 #endif
 904
 905 #ifdef CONFIG_OF
 906 static int s3c24xx_i2c_parse_dt_gpio(struct s3c24xx_i2c *i2c)
 907 {
 908         int idx, gpio, ret;
 909
 910         if (i2c->quirks & QUIRK_NO_GPIO)
 911                 return 0;
 912
 913         for (idx = 0; idx < 2; idx++) {
 914                 gpio = of_get_gpio(i2c->dev->of_node, idx);
 915                 if (!gpio_is_valid(gpio)) {
 916                         dev_err(i2c->dev, "invalid gpio[%d]: %d\n", idx, gpio);
 917                         goto free_gpio;
 918                 }
 919                 i2c->gpios[idx] = gpio;
 920
 921                 ret = gpio_request(gpio, "i2c-bus");
 922                 if (ret) {
 923                         dev_err(i2c->dev, "gpio [%d] request failed\n", gpio);
 924                         goto free_gpio;
 925                 }
 926         }
 927         return 0;
 928
 929 free_gpio:
 930         while (--idx >= 0)
 931                 gpio_free(i2c->gpios[idx]);
 932         return -EINVAL;
 933 }
 934
 935 static void s3c24xx_i2c_dt_gpio_free(struct s3c24xx_i2c *i2c)
 936 {
 937         unsigned int idx;
 938
 939         if (i2c->quirks & QUIRK_NO_GPIO)
 940                 return;
 941
 942         for (idx = 0; idx < 2; idx++)
 943                 gpio_free(i2c->gpios[idx]);
 944 }
 945 #else
 946 static int s3c24xx_i2c_parse_dt_gpio(struct s3c24xx_i2c *i2c)
 947 {
 948         return 0;
 949 }
 950
 951 static void s3c24xx_i2c_dt_gpio_free(struct s3c24xx_i2c *i2c)
 952 {
 953 }
 954 #endif
 955
 956 /* s3c24xx_i2c_init
 957  *
 958  * initialise the controller, set the IO lines and frequency
 959 */
 960
 961 static int s3c24xx_i2c_init(struct s3c24xx_i2c *i2c)
 962 {
 963         unsigned long iicon = S3C2410_IICCON_IRQEN | S3C2410_IICCON_ACKEN;
 964         struct s3c2410_platform_i2c *pdata;
 965         unsigned int freq;
 966
 967         /* get the plafrom data */
 968
 969         pdata = i2c->pdata;
 970
 971         /* write slave address */
 972
 973         writeb(pdata->slave_addr, i2c->regs + S3C2410_IICADD);
 974
 975         dev_info(i2c->dev, "slave address 0x%02x\n", pdata->slave_addr);
 976
 977         writel(iicon, i2c->regs + S3C2410_IICCON);
 978
 979         /* we need to work out the divisors for the clock... */
 980
 981         if (s3c24xx_i2c_clockrate(i2c, &freq) != 0) {
 982                 writel(0, i2c->regs + S3C2410_IICCON);
 983                 dev_err(i2c->dev, "cannot meet bus frequency required\n");
 984                 return -EINVAL;
 985         }
 986
 987         /* todo - check that the i2c lines aren't being dragged anywhere */
 988
 989         dev_info(i2c->dev, "bus frequency set to %d KHz\n", freq);
 990         dev_dbg(i2c->dev, "S3C2410_IICCON=0x%02lx\n", iicon);
 991
 992         return 0;
 993 }
 994
 995 #ifdef CONFIG_OF
 996 /* s3c24xx_i2c_parse_dt
 997  *
 998  * Parse the device tree node and retreive the platform data.
 999 */
1000
1001 static void
1002 s3c24xx_i2c_parse_dt(struct device_node *np, struct s3c24xx_i2c *i2c)
1003 {
1004         struct s3c2410_platform_i2c *pdata = i2c->pdata;
1005
1006         if (!np)
1007                 return;
1008
1009         pdata->bus_num = -1; /* i2c bus number is dynamically assigned */
1010         of_property_read_u32(np, "samsung,i2c-sda-delay", &pdata->sda_delay);
1011         of_property_read_u32(np, "samsung,i2c-slave-addr", &pdata->slave_addr);
1012         of_property_read_u32(np, "samsung,i2c-max-bus-freq",
1013                                 (u32 *)&pdata->frequency);
1014 }
1015 #else
1016 static void
1017 s3c24xx_i2c_parse_dt(struct device_node *np, struct s3c24xx_i2c *i2c)
1018 {
1019         return;
1020 }
1021 #endif
1022
1023 /* s3c24xx_i2c_probe
1024  *
1025  * called by the bus driver when a suitable device is found
1026 */
1027
1028 static int s3c24xx_i2c_probe(struct platform_device *pdev)
1029 {
1030         struct s3c24xx_i2c *i2c;
1031         struct s3c2410_platform_i2c *pdata = NULL;
1032         struct resource *res;
1033         int ret;
1034
1035         if (!pdev->dev.of_node) {
1036                 pdata = pdev->dev.platform_data;
1037                 if (!pdata) {
1038                         dev_err(&pdev->dev, "no platform data\n");
1039                         return -EINVAL;
1040                 }
1041         }
1042
1043         i2c = devm_kzalloc(&pdev->dev, sizeof(struct s3c24xx_i2c), GFP_KERNEL);
1044         if (!i2c) {
1045                 dev_err(&pdev->dev, "no memory for state\n");
1046                 return -ENOMEM;
1047         }
1048
1049         i2c->pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
1050         if (!i2c->pdata) {
1051                 dev_err(&pdev->dev, "no memory for platform data\n");
1052                 return -ENOMEM;
1053         }
1054
1055         i2c->quirks = s3c24xx_get_device_quirks(pdev);
1056         if (pdata)
1057                 memcpy(i2c->pdata, pdata, sizeof(*pdata));
1058         else
1059                 s3c24xx_i2c_parse_dt(pdev->dev.of_node, i2c);
1060
1061         strlcpy(i2c->adap.name, "s3c2410-i2c", sizeof(i2c->adap.name));
1062         i2c->adap.owner   = THIS_MODULE;
1063         i2c->adap.algo    = &s3c24xx_i2c_algorithm;
1064         i2c->adap.retries = 2;
1065         i2c->adap.class   = I2C_CLASS_HWMON | I2C_CLASS_SPD;
1066         i2c->tx_setup     = 50;
1067
1068         init_waitqueue_head(&i2c->wait);
1069
1070         /* find the clock and enable it */
1071
1072         i2c->dev = &pdev->dev;
1073         i2c->clk = devm_clk_get(&pdev->dev, "i2c");
1074         if (IS_ERR(i2c->clk)) {
1075                 dev_err(&pdev->dev, "cannot get clock\n");
1076                 return -ENOENT;
1077         }
1078
1079         dev_dbg(&pdev->dev, "clock source %p\n", i2c->clk);
1080
1081
1082         /* map the registers */
1083
1084         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
1085         i2c->regs = devm_ioremap_resource(&pdev->dev, res);
1086
1087         if (IS_ERR(i2c->regs))
1088                 return PTR_ERR(i2c->regs);
1089
1090         dev_dbg(&pdev->dev, "registers %p (%p)\n",
1091                 i2c->regs, res);
1092
1093         /* setup info block for the i2c core */
1094
1095         i2c->adap.algo_data = i2c;
1096         i2c->adap.dev.parent = &pdev->dev;
1097
1098         i2c->pctrl = devm_pinctrl_get_select_default(i2c->dev);
1099
1100         /* inititalise the i2c gpio lines */
1101
1102         if (i2c->pdata->cfg_gpio) {
1103                 i2c->pdata->cfg_gpio(to_platform_device(i2c->dev));
1104         } else if (IS_ERR(i2c->pctrl) && s3c24xx_i2c_parse_dt_gpio(i2c)) {
1105                 return -EINVAL;
1106         }
1107
1108         /* initialise the i2c controller */
1109
1110         clk_prepare_enable(i2c->clk);
1111         ret = s3c24xx_i2c_init(i2c);
1112         clk_disable_unprepare(i2c->clk);
1113         if (ret != 0) {
1114                 dev_err(&pdev->dev, "I2C controller init failed\n");
1115                 return ret;
1116         }
1117         /* find the IRQ for this unit (note, this relies on the init call to
1118          * ensure no current IRQs pending
1119          */
1120
1121         i2c->irq = ret = platform_get_irq(pdev, 0);
1122         if (ret <= 0) {
1123                 dev_err(&pdev->dev, "cannot find IRQ\n");
1124                 return ret;
1125         }
1126
1127         ret = devm_request_irq(&pdev->dev, i2c->irq, s3c24xx_i2c_irq, 0,
1128                                dev_name(&pdev->dev), i2c);
1129
1130         if (ret != 0) {
1131                 dev_err(&pdev->dev, "cannot claim IRQ %d\n", i2c->irq);
1132                 return ret;
1133         }
1134
1135         ret = s3c24xx_i2c_register_cpufreq(i2c);
1136         if (ret < 0) {
1137                 dev_err(&pdev->dev, "failed to register cpufreq notifier\n");
1138                 return ret;
1139         }
1140
1141         /* Note, previous versions of the driver used i2c_add_adapter()
1142          * to add the bus at any number. We now pass the bus number via
1143          * the platform data, so if unset it will now default to always
1144          * being bus 0.
1145          */
1146
1147         i2c->adap.nr = i2c->pdata->bus_num;
1148         i2c->adap.dev.of_node = pdev->dev.of_node;
1149
1150         ret = i2c_add_numbered_adapter(&i2c->adap);
1151         if (ret < 0) {
1152                 dev_err(&pdev->dev, "failed to add bus to i2c core\n");
1153                 s3c24xx_i2c_deregister_cpufreq(i2c);
1154                 return ret;
1155         }
1156
1157         of_i2c_register_devices(&i2c->adap);
1158         platform_set_drvdata(pdev, i2c);
1159
1160         pm_runtime_enable(&pdev->dev);
1161         pm_runtime_enable(&i2c->adap.dev);
1162
1163         dev_info(&pdev->dev, "%s: S3C I2C adapter\n", dev_name(&i2c->adap.dev));
1164         return 0;
1165 }
1166
1167 /* s3c24xx_i2c_remove
1168  *
1169  * called when device is removed from the bus
1170 */
1171
1172 static int s3c24xx_i2c_remove(struct platform_device *pdev)
1173 {
1174         struct s3c24xx_i2c *i2c = platform_get_drvdata(pdev);
1175
1176         pm_runtime_disable(&i2c->adap.dev);
1177         pm_runtime_disable(&pdev->dev);
1178
1179         s3c24xx_i2c_deregister_cpufreq(i2c);
1180
1181         i2c_del_adapter(&i2c->adap);
1182
1183         clk_disable_unprepare(i2c->clk);
1184
1185         if (pdev->dev.of_node && IS_ERR(i2c->pctrl))
1186                 s3c24xx_i2c_dt_gpio_free(i2c);
1187
1188         return 0;
1189 }
1190
1191 #ifdef CONFIG_PM_SLEEP
1192 static int s3c24xx_i2c_suspend_noirq(struct device *dev)
1193 {
1194         struct platform_device *pdev = to_platform_device(dev);
1195         struct s3c24xx_i2c *i2c = platform_get_drvdata(pdev);
1196
1197         i2c->suspended = 1;
1198
1199         return 0;
1200 }
1201
1202 static int s3c24xx_i2c_resume(struct device *dev)
1203 {
1204         struct platform_device *pdev = to_platform_device(dev);
1205         struct s3c24xx_i2c *i2c = platform_get_drvdata(pdev);
1206
1207         clk_prepare_enable(i2c->clk);
1208         s3c24xx_i2c_init(i2c);
1209         clk_disable_unprepare(i2c->clk);
1210         i2c->suspended = 0;
1211
1212         return 0;
1213 }
1214 #endif
1215
1216 #ifdef CONFIG_PM
1217 static const struct dev_pm_ops s3c24xx_i2c_dev_pm_ops = {
1218 #ifdef CONFIG_PM_SLEEP
1219         .suspend_noirq = s3c24xx_i2c_suspend_noirq,
1220         .resume = s3c24xx_i2c_resume,
1221 #endif
1222 };
1223
1224 #define S3C24XX_DEV_PM_OPS (&s3c24xx_i2c_dev_pm_ops)
1225 #else
1226 #define S3C24XX_DEV_PM_OPS NULL
1227 #endif
1228
1229 /* device driver for platform bus bits */
1230
1231 static struct platform_driver s3c24xx_i2c_driver = {
1232         .probe          = s3c24xx_i2c_probe,
1233         .remove         = s3c24xx_i2c_remove,
1234         .id_table       = s3c24xx_driver_ids,
1235         .driver         = {
1236                 .owner  = THIS_MODULE,
1237                 .name   = "s3c-i2c",
1238                 .pm     = S3C24XX_DEV_PM_OPS,
1239                 .of_match_table = of_match_ptr(s3c24xx_i2c_match),
1240         },
1241 };
1242
1243 static int __init i2c_adap_s3c_init(void)
1244 {
1245         return platform_driver_register(&s3c24xx_i2c_driver);
1246 }
1247 subsys_initcall(i2c_adap_s3c_init);
1248
1249 static void __exit i2c_adap_s3c_exit(void)
1250 {
1251         platform_driver_unregister(&s3c24xx_i2c_driver);
1252 }
1253 module_exit(i2c_adap_s3c_exit);
1254
1255 MODULE_DESCRIPTION("S3C24XX I2C Bus driver");
1256 MODULE_AUTHOR("Ben Dooks, <ben@simtec.co.uk>");
1257 MODULE_LICENSE("GPL");