drivers/i2c/busses/i2c-ibm

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This source file includes following definitions.
dump_iic_regs
iic_interrupt_mode
iic_dev_init
iic_dev_reset
iic_dc_wait
iic_smbus_quick
iic_handler
iic_xfer_result
iic_abort_xfer
iic_wait_for_tc
iic_xfer_bytes
iic_address
iic_invalid_address
iic_address_neq
iic_xfer
iic_func
iic_clckdiv
iic_request_irq
iic_probe
iic_remove
   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 <eugene.surovegin@zultys.com> or <ebs@ebshome.net>
   9  *
  10  * Copyright (c) 2008 PIKA Technologies
  11  * Sean MacLennan <smaclennan@pikatech.com>
  12  *
  13  * Based on original work by
  14  *      Ian DaSilva  <idasilva@mvista.com>
  15  *      Armin Kuster <akuster@mvista.com>
  16  *      Matt Porter  <mporter@mvista.com>
  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 <kmalkki@cc.hut.fi>
  26  *      and even Frodo Looijaard <frodol@dds.nl>
  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_address.h>
  41 #include <linux/of_irq.h>
  42 #include <linux/of_platform.h>
  43 
  44 #include "i2c-ibm_iic.h"
  45 
  46 #define DRIVER_VERSION "2.2"
  47 
  48 MODULE_DESCRIPTION("IBM IIC driver v" DRIVER_VERSION);
  49 MODULE_LICENSE("GPL");
  50 
  51 static bool iic_force_poll;
  52 module_param(iic_force_poll, bool, 0);
  53 MODULE_PARM_DESC(iic_force_poll, "Force polling mode");
  54 
  55 static bool iic_force_fast;
  56 module_param(iic_force_fast, bool, 0);
  57 MODULE_PARM_DESC(iic_force_fast, "Force fast mode (400 kHz)");
  58 
  59 #define DBG_LEVEL 0
  60 
  61 #ifdef DBG
  62 #undef DBG
  63 #endif
  64 
  65 #ifdef DBG2
  66 #undef DBG2
  67 #endif
  68 
  69 #if DBG_LEVEL > 0
  70 #  define DBG(f,x...)   printk(KERN_DEBUG "ibm-iic" f, ##x)
  71 #else
  72 #  define DBG(f,x...)   ((void)0)
  73 #endif
  74 #if DBG_LEVEL > 1
  75 #  define DBG2(f,x...)  DBG(f, ##x)
  76 #else
  77 #  define DBG2(f,x...)  ((void)0)
  78 #endif
  79 #if DBG_LEVEL > 2
  80 static void dump_iic_regs(const char* header, struct ibm_iic_private* dev)
  81 {
  82         volatile struct iic_regs __iomem *iic = dev->vaddr;
  83         printk(KERN_DEBUG "ibm-iic%d: %s\n", dev->idx, header);
  84         printk(KERN_DEBUG
  85                "  cntl     = 0x%02x, mdcntl = 0x%02x\n"
  86                "  sts      = 0x%02x, extsts = 0x%02x\n"
  87                "  clkdiv   = 0x%02x, xfrcnt = 0x%02x\n"
  88                "  xtcntlss = 0x%02x, directcntl = 0x%02x\n",
  89                 in_8(&iic->cntl), in_8(&iic->mdcntl), in_8(&iic->sts),
  90                 in_8(&iic->extsts), in_8(&iic->clkdiv), in_8(&iic->xfrcnt),
  91                 in_8(&iic->xtcntlss), in_8(&iic->directcntl));
  92 }
  93 #  define DUMP_REGS(h,dev)      dump_iic_regs((h),(dev))
  94 #else
  95 #  define DUMP_REGS(h,dev)      ((void)0)
  96 #endif
  97 
  98 /* Bus timings (in ns) for bit-banging */
  99 static struct ibm_iic_timings {
 100         unsigned int hd_sta;
 101         unsigned int su_sto;
 102         unsigned int low;
 103         unsigned int high;
 104         unsigned int buf;
 105 } timings [] = {
 106 /* Standard mode (100 KHz) */
 107 {
 108         .hd_sta = 4000,
 109         .su_sto = 4000,
 110         .low    = 4700,
 111         .high   = 4000,
 112         .buf    = 4700,
 113 },
 114 /* Fast mode (400 KHz) */
 115 {
 116         .hd_sta = 600,
 117         .su_sto = 600,
 118         .low    = 1300,
 119         .high   = 600,
 120         .buf    = 1300,
 121 }};
 122 
 123 /* Enable/disable interrupt generation */
 124 static inline void iic_interrupt_mode(struct ibm_iic_private* dev, int enable)
 125 {
 126         out_8(&dev->vaddr->intmsk, enable ? INTRMSK_EIMTC : 0);
 127 }
 128 
 129 /*
 130  * Initialize IIC interface.
 131  */
 132 static void iic_dev_init(struct ibm_iic_private* dev)
 133 {
 134         volatile struct iic_regs __iomem *iic = dev->vaddr;
 135 
 136         DBG("%d: init\n", dev->idx);
 137 
 138         /* Clear master address */
 139         out_8(&iic->lmadr, 0);
 140         out_8(&iic->hmadr, 0);
 141 
 142         /* Clear slave address */
 143         out_8(&iic->lsadr, 0);
 144         out_8(&iic->hsadr, 0);
 145 
 146         /* Clear status & extended status */
 147         out_8(&iic->sts, STS_SCMP | STS_IRQA);
 148         out_8(&iic->extsts, EXTSTS_IRQP | EXTSTS_IRQD | EXTSTS_LA
 149                             | EXTSTS_ICT | EXTSTS_XFRA);
 150 
 151         /* Set clock divider */
 152         out_8(&iic->clkdiv, dev->clckdiv);
 153 
 154         /* Clear transfer count */
 155         out_8(&iic->xfrcnt, 0);
 156 
 157         /* Clear extended control and status */
 158         out_8(&iic->xtcntlss, XTCNTLSS_SRC | XTCNTLSS_SRS | XTCNTLSS_SWC
 159                             | XTCNTLSS_SWS);
 160 
 161         /* Clear control register */
 162         out_8(&iic->cntl, 0);
 163 
 164         /* Enable interrupts if possible */
 165         iic_interrupt_mode(dev, dev->irq >= 0);
 166 
 167         /* Set mode control */
 168         out_8(&iic->mdcntl, MDCNTL_FMDB | MDCNTL_EINT | MDCNTL_EUBS
 169                             | (dev->fast_mode ? MDCNTL_FSM : 0));
 170 
 171         DUMP_REGS("iic_init", dev);
 172 }
 173 
 174 /*
 175  * Reset IIC interface
 176  */
 177 static void iic_dev_reset(struct ibm_iic_private* dev)
 178 {
 179         volatile struct iic_regs __iomem *iic = dev->vaddr;
 180         int i;
 181         u8 dc;
 182 
 183         DBG("%d: soft reset\n", dev->idx);
 184         DUMP_REGS("reset", dev);
 185 
 186         /* Place chip in the reset state */
 187         out_8(&iic->xtcntlss, XTCNTLSS_SRST);
 188 
 189         /* Check if bus is free */
 190         dc = in_8(&iic->directcntl);
 191         if (!DIRCTNL_FREE(dc)){
 192                 DBG("%d: trying to regain bus control\n", dev->idx);
 193 
 194                 /* Try to set bus free state */
 195                 out_8(&iic->directcntl, DIRCNTL_SDAC | DIRCNTL_SCC);
 196 
 197                 /* Wait until we regain bus control */
 198                 for (i = 0; i < 100; ++i){
 199                         dc = in_8(&iic->directcntl);
 200                         if (DIRCTNL_FREE(dc))
 201                                 break;
 202 
 203                         /* Toggle SCL line */
 204                         dc ^= DIRCNTL_SCC;
 205                         out_8(&iic->directcntl, dc);
 206                         udelay(10);
 207                         dc ^= DIRCNTL_SCC;
 208                         out_8(&iic->directcntl, dc);
 209 
 210                         /* be nice */
 211                         cond_resched();
 212                 }
 213         }
 214 
 215         /* Remove reset */
 216         out_8(&iic->xtcntlss, 0);
 217 
 218         /* Reinitialize interface */
 219         iic_dev_init(dev);
 220 }
 221 
 222 /*
 223  * Do 0-length transaction using bit-banging through IIC_DIRECTCNTL register.
 224  */
 225 
 226 /* Wait for SCL and/or SDA to be high */
 227 static int iic_dc_wait(volatile struct iic_regs __iomem *iic, u8 mask)
 228 {
 229         unsigned long x = jiffies + HZ / 28 + 2;
 230         while ((in_8(&iic->directcntl) & mask) != mask){
 231                 if (unlikely(time_after(jiffies, x)))
 232                         return -1;
 233                 cond_resched();
 234         }
 235         return 0;
 236 }
 237 
 238 static int iic_smbus_quick(struct ibm_iic_private* dev, const struct i2c_msg* p)
 239 {
 240         volatile struct iic_regs __iomem *iic = dev->vaddr;
 241         const struct ibm_iic_timings *t = &timings[dev->fast_mode ? 1 : 0];
 242         u8 mask, v, sda;
 243         int i, res;
 244 
 245         /* Only 7-bit addresses are supported */
 246         if (unlikely(p->flags & I2C_M_TEN)){
 247                 DBG("%d: smbus_quick - 10 bit addresses are not supported\n",
 248                         dev->idx);
 249                 return -EINVAL;
 250         }
 251 
 252         DBG("%d: smbus_quick(0x%02x)\n", dev->idx, p->addr);
 253 
 254         /* Reset IIC interface */
 255         out_8(&iic->xtcntlss, XTCNTLSS_SRST);
 256 
 257         /* Wait for bus to become free */
 258         out_8(&iic->directcntl, DIRCNTL_SDAC | DIRCNTL_SCC);
 259         if (unlikely(iic_dc_wait(iic, DIRCNTL_MSDA | DIRCNTL_MSC)))
 260                 goto err;
 261         ndelay(t->buf);
 262 
 263         /* START */
 264         out_8(&iic->directcntl, DIRCNTL_SCC);
 265         sda = 0;
 266         ndelay(t->hd_sta);
 267 
 268         /* Send address */
 269         v = i2c_8bit_addr_from_msg(p);
 270         for (i = 0, mask = 0x80; i < 8; ++i, mask >>= 1){
 271                 out_8(&iic->directcntl, sda);
 272                 ndelay(t->low / 2);
 273                 sda = (v & mask) ? DIRCNTL_SDAC : 0;
 274                 out_8(&iic->directcntl, sda);
 275                 ndelay(t->low / 2);
 276 
 277                 out_8(&iic->directcntl, DIRCNTL_SCC | sda);
 278                 if (unlikely(iic_dc_wait(iic, DIRCNTL_MSC)))
 279                         goto err;
 280                 ndelay(t->high);
 281         }
 282 
 283         /* ACK */
 284         out_8(&iic->directcntl, sda);
 285         ndelay(t->low / 2);
 286         out_8(&iic->directcntl, DIRCNTL_SDAC);
 287         ndelay(t->low / 2);
 288         out_8(&iic->directcntl, DIRCNTL_SDAC | DIRCNTL_SCC);
 289         if (unlikely(iic_dc_wait(iic, DIRCNTL_MSC)))
 290                 goto err;
 291         res = (in_8(&iic->directcntl) & DIRCNTL_MSDA) ? -EREMOTEIO : 1;
 292         ndelay(t->high);
 293 
 294         /* STOP */
 295         out_8(&iic->directcntl, 0);
 296         ndelay(t->low);
 297         out_8(&iic->directcntl, DIRCNTL_SCC);
 298         if (unlikely(iic_dc_wait(iic, DIRCNTL_MSC)))
 299                 goto err;
 300         ndelay(t->su_sto);
 301         out_8(&iic->directcntl, DIRCNTL_SDAC | DIRCNTL_SCC);
 302 
 303         ndelay(t->buf);
 304 
 305         DBG("%d: smbus_quick -> %s\n", dev->idx, res ? "NACK" : "ACK");
 306 out:
 307         /* Remove reset */
 308         out_8(&iic->xtcntlss, 0);
 309 
 310         /* Reinitialize interface */
 311         iic_dev_init(dev);
 312 
 313         return res;
 314 err:
 315         DBG("%d: smbus_quick - bus is stuck\n", dev->idx);
 316         res = -EREMOTEIO;
 317         goto out;
 318 }
 319 
 320 /*
 321  * IIC interrupt handler
 322  */
 323 static irqreturn_t iic_handler(int irq, void *dev_id)
 324 {
 325         struct ibm_iic_private* dev = (struct ibm_iic_private*)dev_id;
 326         volatile struct iic_regs __iomem *iic = dev->vaddr;
 327 
 328         DBG2("%d: irq handler, STS = 0x%02x, EXTSTS = 0x%02x\n",
 329              dev->idx, in_8(&iic->sts), in_8(&iic->extsts));
 330 
 331         /* Acknowledge IRQ and wakeup iic_wait_for_tc */
 332         out_8(&iic->sts, STS_IRQA | STS_SCMP);
 333         wake_up_interruptible(&dev->wq);
 334 
 335         return IRQ_HANDLED;
 336 }
 337 
 338 /*
 339  * Get master transfer result and clear errors if any.
 340  * Returns the number of actually transferred bytes or error (<0)
 341  */
 342 static int iic_xfer_result(struct ibm_iic_private* dev)
 343 {
 344         volatile struct iic_regs __iomem *iic = dev->vaddr;
 345 
 346         if (unlikely(in_8(&iic->sts) & STS_ERR)){
 347                 DBG("%d: xfer error, EXTSTS = 0x%02x\n", dev->idx,
 348                         in_8(&iic->extsts));
 349 
 350                 /* Clear errors and possible pending IRQs */
 351                 out_8(&iic->extsts, EXTSTS_IRQP | EXTSTS_IRQD |
 352                         EXTSTS_LA | EXTSTS_ICT | EXTSTS_XFRA);
 353 
 354                 /* Flush master data buffer */
 355                 out_8(&iic->mdcntl, in_8(&iic->mdcntl) | MDCNTL_FMDB);
 356 
 357                 /* Is bus free?
 358                  * If error happened during combined xfer
 359                  * IIC interface is usually stuck in some strange
 360                  * state, the only way out - soft reset.
 361                  */
 362                 if ((in_8(&iic->extsts) & EXTSTS_BCS_MASK) != EXTSTS_BCS_FREE){
 363                         DBG("%d: bus is stuck, resetting\n", dev->idx);
 364                         iic_dev_reset(dev);
 365                 }
 366                 return -EREMOTEIO;
 367         }
 368         else
 369                 return in_8(&iic->xfrcnt) & XFRCNT_MTC_MASK;
 370 }
 371 
 372 /*
 373  * Try to abort active transfer.
 374  */
 375 static void iic_abort_xfer(struct ibm_iic_private* dev)
 376 {
 377         volatile struct iic_regs __iomem *iic = dev->vaddr;
 378         unsigned long x;
 379 
 380         DBG("%d: iic_abort_xfer\n", dev->idx);
 381 
 382         out_8(&iic->cntl, CNTL_HMT);
 383 
 384         /*
 385          * Wait for the abort command to complete.
 386          * It's not worth to be optimized, just poll (timeout >= 1 tick)
 387          */
 388         x = jiffies + 2;
 389         while ((in_8(&iic->extsts) & EXTSTS_BCS_MASK) != EXTSTS_BCS_FREE){
 390                 if (time_after(jiffies, x)){
 391                         DBG("%d: abort timeout, resetting...\n", dev->idx);
 392                         iic_dev_reset(dev);
 393                         return;
 394                 }
 395                 schedule();
 396         }
 397 
 398         /* Just to clear errors */
 399         iic_xfer_result(dev);
 400 }
 401 
 402 /*
 403  * Wait for master transfer to complete.
 404  * It puts current process to sleep until we get interrupt or timeout expires.
 405  * Returns the number of transferred bytes or error (<0)
 406  */
 407 static int iic_wait_for_tc(struct ibm_iic_private* dev){
 408 
 409         volatile struct iic_regs __iomem *iic = dev->vaddr;
 410         int ret = 0;
 411 
 412         if (dev->irq >= 0){
 413                 /* Interrupt mode */
 414                 ret = wait_event_interruptible_timeout(dev->wq,
 415                         !(in_8(&iic->sts) & STS_PT), dev->adap.timeout);
 416 
 417                 if (unlikely(ret < 0))
 418                         DBG("%d: wait interrupted\n", dev->idx);
 419                 else if (unlikely(in_8(&iic->sts) & STS_PT)){
 420                         DBG("%d: wait timeout\n", dev->idx);
 421                         ret = -ETIMEDOUT;
 422                 }
 423         }
 424         else {
 425                 /* Polling mode */
 426                 unsigned long x = jiffies + dev->adap.timeout;
 427 
 428                 while (in_8(&iic->sts) & STS_PT){
 429                         if (unlikely(time_after(jiffies, x))){
 430                                 DBG("%d: poll timeout\n", dev->idx);
 431                                 ret = -ETIMEDOUT;
 432                                 break;
 433                         }
 434 
 435                         if (signal_pending(current)){
 436                                 DBG("%d: poll interrupted\n", dev->idx);
 437                                 ret = -ERESTARTSYS;
 438                                 break;
 439                         }
 440                         schedule();
 441                 }
 442         }
 443 
 444         if (unlikely(ret < 0))
 445                 iic_abort_xfer(dev);
 446         else
 447                 ret = iic_xfer_result(dev);
 448 
 449         DBG2("%d: iic_wait_for_tc -> %d\n", dev->idx, ret);
 450 
 451         return ret;
 452 }
 453 
 454 /*
 455  * Low level master transfer routine
 456  */
 457 static int iic_xfer_bytes(struct ibm_iic_private* dev, struct i2c_msg* pm,
 458                           int combined_xfer)
 459 {
 460         volatile struct iic_regs __iomem *iic = dev->vaddr;
 461         char* buf = pm->buf;
 462         int i, j, loops, ret = 0;
 463         int len = pm->len;
 464 
 465         u8 cntl = (in_8(&iic->cntl) & CNTL_AMD) | CNTL_PT;
 466         if (pm->flags & I2C_M_RD)
 467                 cntl |= CNTL_RW;
 468 
 469         loops = (len + 3) / 4;
 470         for (i = 0; i < loops; ++i, len -= 4){
 471                 int count = len > 4 ? 4 : len;
 472                 u8 cmd = cntl | ((count - 1) << CNTL_TCT_SHIFT);
 473 
 474                 if (!(cntl & CNTL_RW))
 475                         for (j = 0; j < count; ++j)
 476                                 out_8((void __iomem *)&iic->mdbuf, *buf++);
 477 
 478                 if (i < loops - 1)
 479                         cmd |= CNTL_CHT;
 480                 else if (combined_xfer)
 481                         cmd |= CNTL_RPST;
 482 
 483                 DBG2("%d: xfer_bytes, %d, CNTL = 0x%02x\n", dev->idx, count, cmd);
 484 
 485                 /* Start transfer */
 486                 out_8(&iic->cntl, cmd);
 487 
 488                 /* Wait for completion */
 489                 ret = iic_wait_for_tc(dev);
 490 
 491                 if (unlikely(ret < 0))
 492                         break;
 493                 else if (unlikely(ret != count)){
 494                         DBG("%d: xfer_bytes, requested %d, transferred %d\n",
 495                                 dev->idx, count, ret);
 496 
 497                         /* If it's not a last part of xfer, abort it */
 498                         if (combined_xfer || (i < loops - 1))
 499                                 iic_abort_xfer(dev);
 500 
 501                         ret = -EREMOTEIO;
 502                         break;
 503                 }
 504 
 505                 if (cntl & CNTL_RW)
 506                         for (j = 0; j < count; ++j)
 507                                 *buf++ = in_8((void __iomem *)&iic->mdbuf);
 508         }
 509 
 510         return ret > 0 ? 0 : ret;
 511 }
 512 
 513 /*
 514  * Set target slave address for master transfer
 515  */
 516 static inline void iic_address(struct ibm_iic_private* dev, struct i2c_msg* msg)
 517 {
 518         volatile struct iic_regs __iomem *iic = dev->vaddr;
 519         u16 addr = msg->addr;
 520 
 521         DBG2("%d: iic_address, 0x%03x (%d-bit)\n", dev->idx,
 522                 addr, msg->flags & I2C_M_TEN ? 10 : 7);
 523 
 524         if (msg->flags & I2C_M_TEN){
 525             out_8(&iic->cntl, CNTL_AMD);
 526             out_8(&iic->lmadr, addr);
 527             out_8(&iic->hmadr, 0xf0 | ((addr >> 7) & 0x06));
 528         }
 529         else {
 530             out_8(&iic->cntl, 0);
 531             out_8(&iic->lmadr, addr << 1);
 532         }
 533 }
 534 
 535 static inline int iic_invalid_address(const struct i2c_msg* p)
 536 {
 537         return (p->addr > 0x3ff) || (!(p->flags & I2C_M_TEN) && (p->addr > 0x7f));
 538 }
 539 
 540 static inline int iic_address_neq(const struct i2c_msg* p1,
 541                                   const struct i2c_msg* p2)
 542 {
 543         return (p1->addr != p2->addr)
 544                 || ((p1->flags & I2C_M_TEN) != (p2->flags & I2C_M_TEN));
 545 }
 546 
 547 /*
 548  * Generic master transfer entrypoint.
 549  * Returns the number of processed messages or error (<0)
 550  */
 551 static int iic_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
 552 {
 553         struct ibm_iic_private* dev = (struct ibm_iic_private*)(i2c_get_adapdata(adap));
 554         volatile struct iic_regs __iomem *iic = dev->vaddr;
 555         int i, ret = 0;
 556 
 557         DBG2("%d: iic_xfer, %d msg(s)\n", dev->idx, num);
 558 
 559         /* Check the sanity of the passed messages.
 560          * Uhh, generic i2c layer is more suitable place for such code...
 561          */
 562         if (unlikely(iic_invalid_address(&msgs[0]))){
 563                 DBG("%d: invalid address 0x%03x (%d-bit)\n", dev->idx,
 564                         msgs[0].addr, msgs[0].flags & I2C_M_TEN ? 10 : 7);
 565                 return -EINVAL;
 566         }
 567         for (i = 0; i < num; ++i){
 568                 if (unlikely(msgs[i].len <= 0)){
 569                         if (num == 1 && !msgs[0].len){
 570                                 /* Special case for I2C_SMBUS_QUICK emulation.
 571                                  * IBM IIC doesn't support 0-length transactions
 572                                  * so we have to emulate them using bit-banging.
 573                                  */
 574                                 return iic_smbus_quick(dev, &msgs[0]);
 575                         }
 576                         DBG("%d: invalid len %d in msg[%d]\n", dev->idx,
 577                                 msgs[i].len, i);
 578                         return -EINVAL;
 579                 }
 580                 if (unlikely(iic_address_neq(&msgs[0], &msgs[i]))){
 581                         DBG("%d: invalid addr in msg[%d]\n", dev->idx, i);
 582                         return -EINVAL;
 583                 }
 584         }
 585 
 586         /* Check bus state */
 587         if (unlikely((in_8(&iic->extsts) & EXTSTS_BCS_MASK) != EXTSTS_BCS_FREE)){
 588                 DBG("%d: iic_xfer, bus is not free\n", dev->idx);
 589 
 590                 /* Usually it means something serious has happened.
 591                  * We *cannot* have unfinished previous transfer
 592                  * so it doesn't make any sense to try to stop it.
 593                  * Probably we were not able to recover from the
 594                  * previous error.
 595                  * The only *reasonable* thing I can think of here
 596                  * is soft reset.  --ebs
 597                  */
 598                 iic_dev_reset(dev);
 599 
 600                 if ((in_8(&iic->extsts) & EXTSTS_BCS_MASK) != EXTSTS_BCS_FREE){
 601                         DBG("%d: iic_xfer, bus is still not free\n", dev->idx);
 602                         return -EREMOTEIO;
 603                 }
 604         }
 605         else {
 606                 /* Flush master data buffer (just in case) */
 607                 out_8(&iic->mdcntl, in_8(&iic->mdcntl) | MDCNTL_FMDB);
 608         }
 609 
 610         /* Load slave address */
 611         iic_address(dev, &msgs[0]);
 612 
 613         /* Do real transfer */
 614         for (i = 0; i < num && !ret; ++i)
 615                 ret = iic_xfer_bytes(dev, &msgs[i], i < num - 1);
 616 
 617         return ret < 0 ? ret : num;
 618 }
 619 
 620 static u32 iic_func(struct i2c_adapter *adap)
 621 {
 622         return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_10BIT_ADDR;
 623 }
 624 
 625 static const struct i2c_algorithm iic_algo = {
 626         .master_xfer    = iic_xfer,
 627         .functionality  = iic_func
 628 };
 629 
 630 /*
 631  * Calculates IICx_CLCKDIV value for a specific OPB clock frequency
 632  */
 633 static inline u8 iic_clckdiv(unsigned int opb)
 634 {
 635         /* Compatibility kludge, should go away after all cards
 636          * are fixed to fill correct value for opbfreq.
 637          * Previous driver version used hardcoded divider value 4,
 638          * it corresponds to OPB frequency from the range (40, 50] MHz
 639          */
 640         if (!opb){
 641                 printk(KERN_WARNING "ibm-iic: using compatibility value for OPB freq,"
 642                         " fix your board specific setup\n");
 643                 opb = 50000000;
 644         }
 645 
 646         /* Convert to MHz */
 647         opb /= 1000000;
 648 
 649         if (opb < 20 || opb > 150){
 650                 printk(KERN_WARNING "ibm-iic: invalid OPB clock frequency %u MHz\n",
 651                         opb);
 652                 opb = opb < 20 ? 20 : 150;
 653         }
 654         return (u8)((opb + 9) / 10 - 1);
 655 }
 656 
 657 static int iic_request_irq(struct platform_device *ofdev,
 658                                      struct ibm_iic_private *dev)
 659 {
 660         struct device_node *np = ofdev->dev.of_node;
 661         int irq;
 662 
 663         if (iic_force_poll)
 664                 return 0;
 665 
 666         irq = irq_of_parse_and_map(np, 0);
 667         if (!irq) {
 668                 dev_err(&ofdev->dev, "irq_of_parse_and_map failed\n");
 669                 return 0;
 670         }
 671 
 672         /* Disable interrupts until we finish initialization, assumes
 673          *  level-sensitive IRQ setup...
 674          */
 675         iic_interrupt_mode(dev, 0);
 676         if (request_irq(irq, iic_handler, 0, "IBM IIC", dev)) {
 677                 dev_err(&ofdev->dev, "request_irq %d failed\n", irq);
 678                 /* Fallback to the polling mode */
 679                 return 0;
 680         }
 681 
 682         return irq;
 683 }
 684 
 685 /*
 686  * Register single IIC interface
 687  */
 688 static int iic_probe(struct platform_device *ofdev)
 689 {
 690         struct device_node *np = ofdev->dev.of_node;
 691         struct ibm_iic_private *dev;
 692         struct i2c_adapter *adap;
 693         const u32 *freq;
 694         int ret;
 695 
 696         dev = kzalloc(sizeof(*dev), GFP_KERNEL);
 697         if (!dev) {
 698                 dev_err(&ofdev->dev, "failed to allocate device data\n");
 699                 return -ENOMEM;
 700         }
 701 
 702         platform_set_drvdata(ofdev, dev);
 703 
 704         dev->vaddr = of_iomap(np, 0);
 705         if (dev->vaddr == NULL) {
 706                 dev_err(&ofdev->dev, "failed to iomap device\n");
 707                 ret = -ENXIO;
 708                 goto error_cleanup;
 709         }
 710 
 711         init_waitqueue_head(&dev->wq);
 712 
 713         dev->irq = iic_request_irq(ofdev, dev);
 714         if (!dev->irq)
 715                 dev_warn(&ofdev->dev, "using polling mode\n");
 716 
 717         /* Board specific settings */
 718         if (iic_force_fast || of_get_property(np, "fast-mode", NULL))
 719                 dev->fast_mode = 1;
 720 
 721         freq = of_get_property(np, "clock-frequency", NULL);
 722         if (freq == NULL) {
 723                 freq = of_get_property(np->parent, "clock-frequency", NULL);
 724                 if (freq == NULL) {
 725                         dev_err(&ofdev->dev, "Unable to get bus frequency\n");
 726                         ret = -EINVAL;
 727                         goto error_cleanup;
 728                 }
 729         }
 730 
 731         dev->clckdiv = iic_clckdiv(*freq);
 732         dev_dbg(&ofdev->dev, "clckdiv = %d\n", dev->clckdiv);
 733 
 734         /* Initialize IIC interface */
 735         iic_dev_init(dev);
 736 
 737         /* Register it with i2c layer */
 738         adap = &dev->adap;
 739         adap->dev.parent = &ofdev->dev;
 740         adap->dev.of_node = of_node_get(np);
 741         strlcpy(adap->name, "IBM IIC", sizeof(adap->name));
 742         i2c_set_adapdata(adap, dev);
 743         adap->class = I2C_CLASS_HWMON | I2C_CLASS_SPD;
 744         adap->algo = &iic_algo;
 745         adap->timeout = HZ;
 746 
 747         ret = i2c_add_adapter(adap);
 748         if (ret  < 0)
 749                 goto error_cleanup;
 750 
 751         dev_info(&ofdev->dev, "using %s mode\n",
 752                  dev->fast_mode ? "fast (400 kHz)" : "standard (100 kHz)");
 753 
 754         return 0;
 755 
 756 error_cleanup:
 757         if (dev->irq) {
 758                 iic_interrupt_mode(dev, 0);
 759                 free_irq(dev->irq, dev);
 760         }
 761 
 762         if (dev->vaddr)
 763                 iounmap(dev->vaddr);
 764 
 765         kfree(dev);
 766         return ret;
 767 }
 768 
 769 /*
 770  * Cleanup initialized IIC interface
 771  */
 772 static int iic_remove(struct platform_device *ofdev)
 773 {
 774         struct ibm_iic_private *dev = platform_get_drvdata(ofdev);
 775 
 776         i2c_del_adapter(&dev->adap);
 777 
 778         if (dev->irq) {
 779                 iic_interrupt_mode(dev, 0);
 780                 free_irq(dev->irq, dev);
 781         }
 782 
 783         iounmap(dev->vaddr);
 784         kfree(dev);
 785 
 786         return 0;
 787 }
 788 
 789 static const struct of_device_id ibm_iic_match[] = {
 790         { .compatible = "ibm,iic", },
 791         {}
 792 };
 793 MODULE_DEVICE_TABLE(of, ibm_iic_match);
 794 
 795 static struct platform_driver ibm_iic_driver = {
 796         .driver = {
 797                 .name = "ibm-iic",
 798                 .of_match_table = ibm_iic_match,
 799         },
 800         .probe  = iic_probe,
 801         .remove = iic_remove,
 802 };
 803 
 804 module_platform_driver(ibm_iic_driver);
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root/drivers/i2c/busses/i2c-ibm_iic.c

DEFINITIONS
