drivers/i2c/busses/i2c-ibm_iic.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * drivers/i2c/busses/i2c-ibm_iic.c
   4  *
   5  * Support for the IIC peripheral on IBM PPC 4xx
   6  *
   7  * Copyright (c) 2003, 2004 Zultys Technologies.
   8  * Eugene Surovegin <[email protected]> or <[email protected]>
   9  *
  10  * Copyright (c) 2008 PIKA Technologies
  11  * Sean MacLennan <[email protected]>
  12  *
  13  * Based on original work by
  14  *      Ian DaSilva  <[email protected]>
  15  *      Armin Kuster <[email protected]>
  16  *      Matt Porter  <[email protected]>
  17  *
  18  *      Copyright 2000-2003 MontaVista Software Inc.
  19  *
  20  * Original driver version was highly leveraged from i2c-elektor.c
  21  *
  22  *      Copyright 1995-97 Simon G. Vogl
  23  *                1998-99 Hans Berglund
  24  *
  25  *      With some changes from Kyösti Mälkki <[email protected]>
  26  *      and even Frodo Looijaard <[email protected]>
  27  */
  28
  29 #include <linux/module.h>
  30 #include <linux/kernel.h>
  31 #include <linux/ioport.h>
  32 #include <linux/delay.h>
  33 #include <linux/slab.h>
  34 #include <linux/interrupt.h>
  35 #include <linux/sched/signal.h>
  36
  37 #include <asm/irq.h>
  38 #include <linux/io.h>
  39 #include <linux/i2c.h>
  40 #include <linux/of.h>
  41 #include <linux/of_address.h>
  42 #include <linux/of_irq.h>
  43 #include <linux/platform_device.h>
  44
  45 #include "i2c-ibm_iic.h"
  46
  47 #define DRIVER_VERSION "2.2"
  48
  49 MODULE_DESCRIPTION("IBM IIC driver v" DRIVER_VERSION);
  50 MODULE_LICENSE("GPL");
  51
  52 static bool iic_force_poll;
  53 module_param(iic_force_poll, bool, 0);
  54 MODULE_PARM_DESC(iic_force_poll, "Force polling mode");
  55
  56 static bool iic_force_fast;
  57 module_param(iic_force_fast, bool, 0);
  58 MODULE_PARM_DESC(iic_force_fast, "Force fast mode (400 kHz)");
  59
  60 #define DBG_LEVEL 0
  61
  62 #ifdef DBG
  63 #undef DBG
  64 #endif
  65
  66 #ifdef DBG2
  67 #undef DBG2
  68 #endif
  69
  70 #if DBG_LEVEL > 0
  71 #  define DBG(f,x...)   printk(KERN_DEBUG "ibm-iic" f, ##x)
  72 #else
  73 #  define DBG(f,x...)   ((void)0)
  74 #endif
  75 #if DBG_LEVEL > 1
  76 #  define DBG2(f,x...)  DBG(f, ##x)
  77 #else
  78 #  define DBG2(f,x...)  ((void)0)
  79 #endif
  80 #if DBG_LEVEL > 2
  81 static void dump_iic_regs(const char* header, struct ibm_iic_private* dev)
  82 {
  83         volatile struct iic_regs __iomem *iic = dev->vaddr;
  84         printk(KERN_DEBUG "ibm-iic%d: %s\n", dev->idx, header);
  85         printk(KERN_DEBUG
  86                "  cntl     = 0x%02x, mdcntl = 0x%02x\n"
  87                "  sts      = 0x%02x, extsts = 0x%02x\n"
  88                "  clkdiv   = 0x%02x, xfrcnt = 0x%02x\n"
  89                "  xtcntlss = 0x%02x, directcntl = 0x%02x\n",
  90                 in_8(&iic->cntl), in_8(&iic->mdcntl), in_8(&iic->sts),
  91                 in_8(&iic->extsts), in_8(&iic->clkdiv), in_8(&iic->xfrcnt),
  92                 in_8(&iic->xtcntlss), in_8(&iic->directcntl));
  93 }
  94 #  define DUMP_REGS(h,dev)      dump_iic_regs((h),(dev))
  95 #else
  96 #  define DUMP_REGS(h,dev)      ((void)0)
  97 #endif
  98
  99 /* Bus timings (in ns) for bit-banging */
 100 static struct ibm_iic_timings {
 101         unsigned int hd_sta;
 102         unsigned int su_sto;
 103         unsigned int low;
 104         unsigned int high;
 105         unsigned int buf;
 106 } timings [] = {
 107 /* Standard mode (100 KHz) */
 108 {
 109         .hd_sta = 4000,
 110         .su_sto = 4000,
 111         .low    = 4700,
 112         .high   = 4000,
 113         .buf    = 4700,
 114 },
 115 /* Fast mode (400 KHz) */
 116 {
 117         .hd_sta = 600,
 118         .su_sto = 600,
 119         .low    = 1300,
 120         .high   = 600,
 121         .buf    = 1300,
 122 }};
 123
 124 /* Enable/disable interrupt generation */
 125 static inline void iic_interrupt_mode(struct ibm_iic_private* dev, int enable)
 126 {
 127         out_8(&dev->vaddr->intmsk, enable ? INTRMSK_EIMTC : 0);
 128 }
 129
 130 /*
 131  * Initialize IIC interface.
 132  */
 133 static void iic_dev_init(struct ibm_iic_private* dev)
 134 {
 135         volatile struct iic_regs __iomem *iic = dev->vaddr;
 136
 137         DBG("%d: init\n", dev->idx);
 138
 139         /* Clear remote target address */
 140         out_8(&iic->lmadr, 0);
 141         out_8(&iic->hmadr, 0);
 142
 143         /* Clear local target address */
 144         out_8(&iic->lsadr, 0);
 145         out_8(&iic->hsadr, 0);
 146
 147         /* Clear status & extended status */
 148         out_8(&iic->sts, STS_SCMP | STS_IRQA);
 149         out_8(&iic->extsts, EXTSTS_IRQP | EXTSTS_IRQD | EXTSTS_LA
 150                             | EXTSTS_ICT | EXTSTS_XFRA);
 151
 152         /* Set clock divider */
 153         out_8(&iic->clkdiv, dev->clckdiv);
 154
 155         /* Clear transfer count */
 156         out_8(&iic->xfrcnt, 0);
 157
 158         /* Clear extended control and status */
 159         out_8(&iic->xtcntlss, XTCNTLSS_SRC | XTCNTLSS_SRS | XTCNTLSS_SWC
 160                             | XTCNTLSS_SWS);
 161
 162         /* Clear control register */
 163         out_8(&iic->cntl, 0);
 164
 165         /* Enable interrupts if possible */
 166         iic_interrupt_mode(dev, dev->irq >= 0);
 167
 168         /* Set mode control */
 169         out_8(&iic->mdcntl, MDCNTL_FMDB | MDCNTL_EINT | MDCNTL_EUBS
 170                             | (dev->fast_mode ? MDCNTL_FSM : 0));
 171
 172         DUMP_REGS("iic_init", dev);
 173 }
 174
 175 /*
 176  * Reset IIC interface
 177  */
 178 static void iic_dev_reset(struct ibm_iic_private* dev)
 179 {
 180         volatile struct iic_regs __iomem *iic = dev->vaddr;
 181         int i;
 182         u8 dc;
 183
 184         DBG("%d: soft reset\n", dev->idx);
 185         DUMP_REGS("reset", dev);
 186
 187         /* Place chip in the reset state */
 188         out_8(&iic->xtcntlss, XTCNTLSS_SRST);
 189
 190         /* Check if bus is free */
 191         dc = in_8(&iic->directcntl);
 192         if (!DIRCTNL_FREE(dc)){
 193                 DBG("%d: trying to regain bus control\n", dev->idx);
 194
 195                 /* Try to set bus free state */
 196                 out_8(&iic->directcntl, DIRCNTL_SDAC | DIRCNTL_SCC);
 197
 198                 /* Wait until we regain bus control */
 199                 for (i = 0; i < 100; ++i){
 200                         dc = in_8(&iic->directcntl);
 201                         if (DIRCTNL_FREE(dc))
 202                                 break;
 203
 204                         /* Toggle SCL line */
 205                         dc ^= DIRCNTL_SCC;
 206                         out_8(&iic->directcntl, dc);
 207                         udelay(10);
 208                         dc ^= DIRCNTL_SCC;
 209                         out_8(&iic->directcntl, dc);
 210
 211                         /* be nice */
 212                         cond_resched();
 213                 }
 214         }
 215
 216         /* Remove reset */
 217         out_8(&iic->xtcntlss, 0);
 218
 219         /* Reinitialize interface */
 220         iic_dev_init(dev);
 221 }
 222
 223 /*
 224  * Do 0-length transaction using bit-banging through IIC_DIRECTCNTL register.
 225  */
 226
 227 /* Wait for SCL and/or SDA to be high */
 228 static int iic_dc_wait(volatile struct iic_regs __iomem *iic, u8 mask)
 229 {
 230         unsigned long x = jiffies + HZ / 28 + 2;
 231         while ((in_8(&iic->directcntl) & mask) != mask){
 232                 if (unlikely(time_after(jiffies, x)))
 233                         return -1;
 234                 cond_resched();
 235         }
 236         return 0;
 237 }
 238
 239 static int iic_smbus_quick(struct ibm_iic_private* dev, const struct i2c_msg* p)
 240 {
 241         volatile struct iic_regs __iomem *iic = dev->vaddr;
 242         const struct ibm_iic_timings *t = &timings[dev->fast_mode ? 1 : 0];
 243         u8 mask, v, sda;
 244         int i, res;
 245
 246         /* Only 7-bit addresses are supported */
 247         if (unlikely(p->flags & I2C_M_TEN)){
 248                 DBG("%d: smbus_quick - 10 bit addresses are not supported\n",
 249                         dev->idx);
 250                 return -EINVAL;
 251         }
 252
 253         DBG("%d: smbus_quick(0x%02x)\n", dev->idx, p->addr);
 254
 255         /* Reset IIC interface */
 256         out_8(&iic->xtcntlss, XTCNTLSS_SRST);
 257
 258         /* Wait for bus to become free */
 259         out_8(&iic->directcntl, DIRCNTL_SDAC | DIRCNTL_SCC);
 260         if (unlikely(iic_dc_wait(iic, DIRCNTL_MSDA | DIRCNTL_MSC)))
 261                 goto err;
 262         ndelay(t->buf);
 263
 264         /* START */
 265         out_8(&iic->directcntl, DIRCNTL_SCC);
 266         sda = 0;
 267         ndelay(t->hd_sta);
 268
 269         /* Send address */
 270         v = i2c_8bit_addr_from_msg(p);
 271         for (i = 0, mask = 0x80; i < 8; ++i, mask >>= 1){
 272                 out_8(&iic->directcntl, sda);
 273                 ndelay(t->low / 2);
 274                 sda = (v & mask) ? DIRCNTL_SDAC : 0;
 275                 out_8(&iic->directcntl, sda);
 276                 ndelay(t->low / 2);
 277
 278                 out_8(&iic->directcntl, DIRCNTL_SCC | sda);
 279                 if (unlikely(iic_dc_wait(iic, DIRCNTL_MSC)))
 280                         goto err;
 281                 ndelay(t->high);
 282         }
 283
 284         /* ACK */
 285         out_8(&iic->directcntl, sda);
 286         ndelay(t->low / 2);
 287         out_8(&iic->directcntl, DIRCNTL_SDAC);
 288         ndelay(t->low / 2);
 289         out_8(&iic->directcntl, DIRCNTL_SDAC | DIRCNTL_SCC);
 290         if (unlikely(iic_dc_wait(iic, DIRCNTL_MSC)))
 291                 goto err;
 292         res = (in_8(&iic->directcntl) & DIRCNTL_MSDA) ? -EREMOTEIO : 1;
 293         ndelay(t->high);
 294
 295         /* STOP */
 296         out_8(&iic->directcntl, 0);
 297         ndelay(t->low);
 298         out_8(&iic->directcntl, DIRCNTL_SCC);
 299         if (unlikely(iic_dc_wait(iic, DIRCNTL_MSC)))
 300                 goto err;
 301         ndelay(t->su_sto);
 302         out_8(&iic->directcntl, DIRCNTL_SDAC | DIRCNTL_SCC);
 303
 304         ndelay(t->buf);
 305
 306         DBG("%d: smbus_quick -> %s\n", dev->idx, res ? "NACK" : "ACK");
 307 out:
 308         /* Remove reset */
 309         out_8(&iic->xtcntlss, 0);
 310
 311         /* Reinitialize interface */
 312         iic_dev_init(dev);
 313
 314         return res;
 315 err:
 316         DBG("%d: smbus_quick - bus is stuck\n", dev->idx);
 317         res = -EREMOTEIO;
 318         goto out;
 319 }
 320
 321 /*
 322  * IIC interrupt handler
 323  */
 324 static irqreturn_t iic_handler(int irq, void *dev_id)
 325 {
 326         struct ibm_iic_private* dev = (struct ibm_iic_private*)dev_id;
 327         volatile struct iic_regs __iomem *iic = dev->vaddr;
 328
 329         DBG2("%d: irq handler, STS = 0x%02x, EXTSTS = 0x%02x\n",
 330              dev->idx, in_8(&iic->sts), in_8(&iic->extsts));
 331
 332         /* Acknowledge IRQ and wakeup iic_wait_for_tc */
 333         out_8(&iic->sts, STS_IRQA | STS_SCMP);
 334         wake_up_interruptible(&dev->wq);
 335
 336         return IRQ_HANDLED;
 337 }
 338
 339 /*
 340  * Get controller transfer result and clear errors if any.
 341  * Returns the number of actually transferred bytes or error (<0)
 342  */
 343 static int iic_xfer_result(struct ibm_iic_private* dev)
 344 {
 345         volatile struct iic_regs __iomem *iic = dev->vaddr;
 346
 347         if (unlikely(in_8(&iic->sts) & STS_ERR)){
 348                 DBG("%d: xfer error, EXTSTS = 0x%02x\n", dev->idx,
 349                         in_8(&iic->extsts));
 350
 351                 /* Clear errors and possible pending IRQs */
 352                 out_8(&iic->extsts, EXTSTS_IRQP | EXTSTS_IRQD |
 353                         EXTSTS_LA | EXTSTS_ICT | EXTSTS_XFRA);
 354
 355                 /* Flush controller data buffer */
 356                 out_8(&iic->mdcntl, in_8(&iic->mdcntl) | MDCNTL_FMDB);
 357
 358                 /* Is bus free?
 359                  * If error happened during combined xfer
 360                  * IIC interface is usually stuck in some strange
 361                  * state, the only way out - soft reset.
 362                  */
 363                 if ((in_8(&iic->extsts) & EXTSTS_BCS_MASK) != EXTSTS_BCS_FREE){
 364                         DBG("%d: bus is stuck, resetting\n", dev->idx);
 365                         iic_dev_reset(dev);
 366                 }
 367                 return -EREMOTEIO;
 368         }
 369         else
 370                 return in_8(&iic->xfrcnt) & XFRCNT_MTC_MASK;
 371 }
 372
 373 /*
 374  * Try to abort active transfer.
 375  */
 376 static void iic_abort_xfer(struct ibm_iic_private* dev)
 377 {
 378         volatile struct iic_regs __iomem *iic = dev->vaddr;
 379         unsigned long x;
 380
 381         DBG("%d: iic_abort_xfer\n", dev->idx);
 382
 383         out_8(&iic->cntl, CNTL_HMT);
 384
 385         /*
 386          * Wait for the abort command to complete.
 387          * It's not worth to be optimized, just poll (timeout >= 1 tick)
 388          */
 389         x = jiffies + 2;
 390         while ((in_8(&iic->extsts) & EXTSTS_BCS_MASK) != EXTSTS_BCS_FREE){
 391                 if (time_after(jiffies, x)){
 392                         DBG("%d: abort timeout, resetting...\n", dev->idx);
 393                         iic_dev_reset(dev);
 394                         return;
 395                 }
 396                 schedule();
 397         }
 398
 399         /* Just to clear errors */
 400         iic_xfer_result(dev);
 401 }
 402
 403 /*
 404  * Wait for controller transfer to complete.
 405  * It puts current process to sleep until we get interrupt or timeout expires.
 406  * Returns the number of transferred bytes or error (<0)
 407  */
 408 static int iic_wait_for_tc(struct ibm_iic_private* dev){
 409
 410         volatile struct iic_regs __iomem *iic = dev->vaddr;
 411         int ret = 0;
 412
 413         if (dev->irq >= 0){
 414                 /* Interrupt mode */
 415                 ret = wait_event_interruptible_timeout(dev->wq,
 416                         !(in_8(&iic->sts) & STS_PT), dev->adap.timeout);
 417
 418                 if (unlikely(ret < 0))
 419                         DBG("%d: wait interrupted\n", dev->idx);
 420                 else if (unlikely(in_8(&iic->sts) & STS_PT)){
 421                         DBG("%d: wait timeout\n", dev->idx);
 422                         ret = -ETIMEDOUT;
 423                 }
 424         }
 425         else {
 426                 /* Polling mode */
 427                 unsigned long x = jiffies + dev->adap.timeout;
 428
 429                 while (in_8(&iic->sts) & STS_PT){
 430                         if (unlikely(time_after(jiffies, x))){
 431                                 DBG("%d: poll timeout\n", dev->idx);
 432                                 ret = -ETIMEDOUT;
 433                                 break;
 434                         }
 435
 436                         if (signal_pending(current)){
 437                                 DBG("%d: poll interrupted\n", dev->idx);
 438                                 ret = -ERESTARTSYS;
 439                                 break;
 440                         }
 441                         schedule();
 442                 }
 443         }
 444
 445         if (unlikely(ret < 0))
 446                 iic_abort_xfer(dev);
 447         else
 448                 ret = iic_xfer_result(dev);
 449
 450         DBG2("%d: iic_wait_for_tc -> %d\n", dev->idx, ret);
 451
 452         return ret;
 453 }
 454
 455 static int iic_xfer_bytes(struct ibm_iic_private* dev, struct i2c_msg* pm,
 456                           int combined_xfer)
 457 {
 458         volatile struct iic_regs __iomem *iic = dev->vaddr;
 459         char* buf = pm->buf;
 460         int i, j, loops, ret = 0;
 461         int len = pm->len;
 462
 463         u8 cntl = (in_8(&iic->cntl) & CNTL_AMD) | CNTL_PT;
 464         if (pm->flags & I2C_M_RD)
 465                 cntl |= CNTL_RW;
 466
 467         loops = (len + 3) / 4;
 468         for (i = 0; i < loops; ++i, len -= 4){
 469                 int count = len > 4 ? 4 : len;
 470                 u8 cmd = cntl | ((count - 1) << CNTL_TCT_SHIFT);
 471
 472                 if (!(cntl & CNTL_RW))
 473                         for (j = 0; j < count; ++j)
 474                                 out_8((void __iomem *)&iic->mdbuf, *buf++);
 475
 476                 if (i < loops - 1)
 477                         cmd |= CNTL_CHT;
 478                 else if (combined_xfer)
 479                         cmd |= CNTL_RPST;
 480
 481                 DBG2("%d: xfer_bytes, %d, CNTL = 0x%02x\n", dev->idx, count, cmd);
 482
 483                 /* Start transfer */
 484                 out_8(&iic->cntl, cmd);
 485
 486                 /* Wait for completion */
 487                 ret = iic_wait_for_tc(dev);
 488
 489                 if (unlikely(ret < 0))
 490                         break;
 491                 else if (unlikely(ret != count)){
 492                         DBG("%d: xfer_bytes, requested %d, transferred %d\n",
 493                                 dev->idx, count, ret);
 494
 495                         /* If it's not a last part of xfer, abort it */
 496                         if (combined_xfer || (i < loops - 1))
 497                                 iic_abort_xfer(dev);
 498
 499                         ret = -EREMOTEIO;
 500                         break;
 501                 }
 502
 503                 if (cntl & CNTL_RW)
 504                         for (j = 0; j < count; ++j)
 505                                 *buf++ = in_8((void __iomem *)&iic->mdbuf);
 506         }
 507
 508         return ret > 0 ? 0 : ret;
 509 }
 510
 511 /* Set remote target address for transfer */
 512 static inline void iic_address(struct ibm_iic_private* dev, struct i2c_msg* msg)
 513 {
 514         volatile struct iic_regs __iomem *iic = dev->vaddr;
 515         u16 addr = msg->addr;
 516
 517         DBG2("%d: iic_address, 0x%03x (%d-bit)\n", dev->idx,
 518                 addr, msg->flags & I2C_M_TEN ? 10 : 7);
 519
 520         if (msg->flags & I2C_M_TEN){
 521             out_8(&iic->cntl, CNTL_AMD);
 522             out_8(&iic->lmadr, addr);
 523             out_8(&iic->hmadr, 0xf0 | ((addr >> 7) & 0x06));
 524         }
 525         else {
 526             out_8(&iic->cntl, 0);
 527             out_8(&iic->lmadr, addr << 1);
 528         }
 529 }
 530
 531 static inline int iic_invalid_address(const struct i2c_msg* p)
 532 {
 533         return (p->addr > 0x3ff) || (!(p->flags & I2C_M_TEN) && (p->addr > 0x7f));
 534 }
 535
 536 static inline int iic_address_neq(const struct i2c_msg* p1,
 537                                   const struct i2c_msg* p2)
 538 {
 539         return (p1->addr != p2->addr)
 540                 || ((p1->flags & I2C_M_TEN) != (p2->flags & I2C_M_TEN));
 541 }
 542
 543 /*
 544  * Generic transfer entrypoint.
 545  * Returns the number of processed messages or error (<0)
 546  */
 547 static int iic_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
 548 {
 549         struct ibm_iic_private* dev = (struct ibm_iic_private*)(i2c_get_adapdata(adap));
 550         volatile struct iic_regs __iomem *iic = dev->vaddr;
 551         int i, ret = 0;
 552
 553         DBG2("%d: iic_xfer, %d msg(s)\n", dev->idx, num);
 554
 555         /* Check the sanity of the passed messages.
 556          * Uhh, generic i2c layer is more suitable place for such code...
 557          */
 558         if (unlikely(iic_invalid_address(&msgs[0]))){
 559                 DBG("%d: invalid address 0x%03x (%d-bit)\n", dev->idx,
 560                         msgs[0].addr, msgs[0].flags & I2C_M_TEN ? 10 : 7);
 561                 return -EINVAL;
 562         }
 563         for (i = 0; i < num; ++i){
 564                 if (unlikely(msgs[i].len <= 0)){
 565                         if (num == 1 && !msgs[0].len){
 566                                 /* Special case for I2C_SMBUS_QUICK emulation.
 567                                  * IBM IIC doesn't support 0-length transactions
 568                                  * so we have to emulate them using bit-banging.
 569                                  */
 570                                 return iic_smbus_quick(dev, &msgs[0]);
 571                         }
 572                         DBG("%d: invalid len %d in msg[%d]\n", dev->idx,
 573                                 msgs[i].len, i);
 574                         return -EINVAL;
 575                 }
 576                 if (unlikely(iic_address_neq(&msgs[0], &msgs[i]))){
 577                         DBG("%d: invalid addr in msg[%d]\n", dev->idx, i);
 578                         return -EINVAL;
 579                 }
 580         }
 581
 582         /* Check bus state */
 583         if (unlikely((in_8(&iic->extsts) & EXTSTS_BCS_MASK) != EXTSTS_BCS_FREE)){
 584                 DBG("%d: iic_xfer, bus is not free\n", dev->idx);
 585
 586                 /* Usually it means something serious has happened.
 587                  * We *cannot* have unfinished previous transfer
 588                  * so it doesn't make any sense to try to stop it.
 589                  * Probably we were not able to recover from the
 590                  * previous error.
 591                  * The only *reasonable* thing I can think of here
 592                  * is soft reset.  --ebs
 593                  */
 594                 iic_dev_reset(dev);
 595
 596                 if ((in_8(&iic->extsts) & EXTSTS_BCS_MASK) != EXTSTS_BCS_FREE){
 597                         DBG("%d: iic_xfer, bus is still not free\n", dev->idx);
 598                         return -EREMOTEIO;
 599                 }
 600         }
 601         else {
 602                 /* Flush controller data buffer (just in case) */
 603                 out_8(&iic->mdcntl, in_8(&iic->mdcntl) | MDCNTL_FMDB);
 604         }
 605
 606         /* Load target address */
 607         iic_address(dev, &msgs[0]);
 608
 609         /* Do real transfer */
 610         for (i = 0; i < num && !ret; ++i)
 611                 ret = iic_xfer_bytes(dev, &msgs[i], i < num - 1);
 612
 613         return ret < 0 ? ret : num;
 614 }
 615
 616 static u32 iic_func(struct i2c_adapter *adap)
 617 {
 618         return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_10BIT_ADDR;
 619 }
 620
 621 static const struct i2c_algorithm iic_algo = {
 622         .xfer = iic_xfer,
 623         .functionality = iic_func
 624 };
 625
 626 /*
 627  * Calculates IICx_CLCKDIV value for a specific OPB clock frequency
 628  */
 629 static inline u8 iic_clckdiv(unsigned int opb)
 630 {
 631         /* Compatibility kludge, should go away after all cards
 632          * are fixed to fill correct value for opbfreq.
 633          * Previous driver version used hardcoded divider value 4,
 634          * it corresponds to OPB frequency from the range (40, 50] MHz
 635          */
 636         if (!opb){
 637                 printk(KERN_WARNING "ibm-iic: using compatibility value for OPB freq,"
 638                         " fix your board specific setup\n");
 639                 opb = 50000000;
 640         }
 641
 642         /* Convert to MHz */
 643         opb /= 1000000;
 644
 645         if (opb < 20 || opb > 150){
 646                 printk(KERN_WARNING "ibm-iic: invalid OPB clock frequency %u MHz\n",
 647                         opb);
 648                 opb = opb < 20 ? 20 : 150;
 649         }
 650         return (u8)((opb + 9) / 10 - 1);
 651 }
 652
 653 static int iic_request_irq(struct platform_device *ofdev,
 654                                      struct ibm_iic_private *dev)
 655 {
 656         struct device_node *np = ofdev->dev.of_node;
 657         int irq;
 658
 659         if (iic_force_poll)
 660                 return 0;
 661
 662         irq = irq_of_parse_and_map(np, 0);
 663         if (!irq) {
 664                 dev_err(&ofdev->dev, "irq_of_parse_and_map failed\n");
 665                 return 0;
 666         }
 667
 668         /* Disable interrupts until we finish initialization, assumes
 669          *  level-sensitive IRQ setup...
 670          */
 671         iic_interrupt_mode(dev, 0);
 672         if (request_irq(irq, iic_handler, 0, "IBM IIC", dev)) {
 673                 dev_err(&ofdev->dev, "request_irq %d failed\n", irq);
 674                 /* Fallback to the polling mode */
 675                 return 0;
 676         }
 677
 678         return irq;
 679 }
 680
 681 /*
 682  * Register single IIC interface
 683  */
 684 static int iic_probe(struct platform_device *ofdev)
 685 {
 686         struct device_node *np = ofdev->dev.of_node;
 687         struct ibm_iic_private *dev;
 688         struct i2c_adapter *adap;
 689         const u32 *freq;
 690         int ret;
 691
 692         dev = kzalloc(sizeof(*dev), GFP_KERNEL);
 693         if (!dev)
 694                 return -ENOMEM;
 695
 696         platform_set_drvdata(ofdev, dev);
 697
 698         dev->vaddr = of_iomap(np, 0);
 699         if (dev->vaddr == NULL) {
 700                 dev_err(&ofdev->dev, "failed to iomap device\n");
 701                 ret = -ENXIO;
 702                 goto error_cleanup;
 703         }
 704
 705         init_waitqueue_head(&dev->wq);
 706
 707         dev->irq = iic_request_irq(ofdev, dev);
 708         if (!dev->irq)
 709                 dev_warn(&ofdev->dev, "using polling mode\n");
 710
 711         /* Board specific settings */
 712         if (iic_force_fast || of_get_property(np, "fast-mode", NULL))
 713                 dev->fast_mode = 1;
 714
 715         freq = of_get_property(np, "clock-frequency", NULL);
 716         if (freq == NULL) {
 717                 freq = of_get_property(np->parent, "clock-frequency", NULL);
 718                 if (freq == NULL) {
 719                         dev_err(&ofdev->dev, "Unable to get bus frequency\n");
 720                         ret = -EINVAL;
 721                         goto error_cleanup;
 722                 }
 723         }
 724
 725         dev->clckdiv = iic_clckdiv(*freq);
 726         dev_dbg(&ofdev->dev, "clckdiv = %d\n", dev->clckdiv);
 727
 728         /* Initialize IIC interface */
 729         iic_dev_init(dev);
 730
 731         /* Register it with i2c layer */
 732         adap = &dev->adap;
 733         adap->dev.parent = &ofdev->dev;
 734         adap->dev.of_node = of_node_get(np);
 735         strscpy(adap->name, "IBM IIC", sizeof(adap->name));
 736         i2c_set_adapdata(adap, dev);
 737         adap->class = I2C_CLASS_HWMON;
 738         adap->algo = &iic_algo;
 739         adap->timeout = HZ;
 740
 741         ret = i2c_add_adapter(adap);
 742         if (ret  < 0)
 743                 goto error_cleanup;
 744
 745         dev_info(&ofdev->dev, "using %s mode\n",
 746                  dev->fast_mode ? "fast (400 kHz)" : "standard (100 kHz)");
 747
 748         return 0;
 749
 750 error_cleanup:
 751         if (dev->irq) {
 752                 iic_interrupt_mode(dev, 0);
 753                 free_irq(dev->irq, dev);
 754         }
 755
 756         if (dev->vaddr)
 757                 iounmap(dev->vaddr);
 758
 759         kfree(dev);
 760         return ret;
 761 }
 762
 763 /*
 764  * Cleanup initialized IIC interface
 765  */
 766 static void iic_remove(struct platform_device *ofdev)
 767 {
 768         struct ibm_iic_private *dev = platform_get_drvdata(ofdev);
 769
 770         i2c_del_adapter(&dev->adap);
 771
 772         if (dev->irq) {
 773                 iic_interrupt_mode(dev, 0);
 774                 free_irq(dev->irq, dev);
 775         }
 776
 777         iounmap(dev->vaddr);
 778         kfree(dev);
 779 }
 780
 781 static const struct of_device_id ibm_iic_match[] = {
 782         { .compatible = "ibm,iic", },
 783         {}
 784 };
 785 MODULE_DEVICE_TABLE(of, ibm_iic_match);
 786
 787 static struct platform_driver ibm_iic_driver = {
 788         .driver = {
 789                 .name = "ibm-iic",
 790                 .of_match_table = ibm_iic_match,
 791         },
 792         .probe  = iic_probe,
 793         .remove = iic_remove,
 794 };
 795
 796 module_platform_driver(ibm_iic_driver);