drivers/i2c/busses/i2c-octeon-core.c

   1 /*
   2  * (C) Copyright 2009-2010
   3  * Nokia Siemens Networks, michael.lawnick.ext@nsn.com
   4  *
   5  * Portions Copyright (C) 2010 - 2016 Cavium, Inc.
   6  *
   7  * This file contains the shared part of the driver for the i2c adapter in
   8  * Cavium Networks' OCTEON processors and ThunderX SOCs.
   9  *
  10  * This file is licensed under the terms of the GNU General Public
  11  * License version 2. This program is licensed "as is" without any
  12  * warranty of any kind, whether express or implied.
  13  */
  14
  15 #include <linux/delay.h>
  16 #include <linux/i2c.h>
  17 #include <linux/interrupt.h>
  18 #include <linux/kernel.h>
  19 #include <linux/module.h>
  20
  21 #include "i2c-octeon-core.h"
  22
  23 /* interrupt service routine */
  24 irqreturn_t octeon_i2c_isr(int irq, void *dev_id)
  25 {
  26         struct octeon_i2c *i2c = dev_id;
  27
  28         i2c->int_disable(i2c);
  29         wake_up(&i2c->queue);
  30
  31         return IRQ_HANDLED;
  32 }
  33
  34 static bool octeon_i2c_test_iflg(struct octeon_i2c *i2c)
  35 {
  36         return (octeon_i2c_ctl_read(i2c) & TWSI_CTL_IFLG);
  37 }
  38
  39 /**
  40  * octeon_i2c_wait - wait for the IFLG to be set
  41  * @i2c: The struct octeon_i2c
  42  *
  43  * Returns 0 on success, otherwise a negative errno.
  44  */
  45 static int octeon_i2c_wait(struct octeon_i2c *i2c)
  46 {
  47         long time_left;
  48
  49         /*
  50          * Some chip revisions don't assert the irq in the interrupt
  51          * controller. So we must poll for the IFLG change.
  52          */
  53         if (i2c->broken_irq_mode) {
  54                 u64 end = get_jiffies_64() + i2c->adap.timeout;
  55
  56                 while (!octeon_i2c_test_iflg(i2c) &&
  57                        time_before64(get_jiffies_64(), end))
  58                         usleep_range(I2C_OCTEON_EVENT_WAIT / 2, I2C_OCTEON_EVENT_WAIT);
  59
  60                 return octeon_i2c_test_iflg(i2c) ? 0 : -ETIMEDOUT;
  61         }
  62
  63         i2c->int_enable(i2c);
  64         time_left = wait_event_timeout(i2c->queue, octeon_i2c_test_iflg(i2c),
  65                                        i2c->adap.timeout);
  66         i2c->int_disable(i2c);
  67
  68         if (i2c->broken_irq_check && !time_left &&
  69             octeon_i2c_test_iflg(i2c)) {
  70                 dev_err(i2c->dev, "broken irq connection detected, switching to polling mode.\n");
  71                 i2c->broken_irq_mode = true;
  72                 return 0;
  73         }
  74
  75         if (!time_left)
  76                 return -ETIMEDOUT;
  77
  78         return 0;
  79 }
  80
  81 static bool octeon_i2c_hlc_test_valid(struct octeon_i2c *i2c)
  82 {
  83         return (__raw_readq(i2c->twsi_base + SW_TWSI(i2c)) & SW_TWSI_V) == 0;
  84 }
  85
  86 static void octeon_i2c_hlc_int_clear(struct octeon_i2c *i2c)
  87 {
  88         /* clear ST/TS events, listen for neither */
  89         octeon_i2c_write_int(i2c, TWSI_INT_ST_INT | TWSI_INT_TS_INT);
  90 }
  91
  92 /*
  93  * Cleanup low-level state & enable high-level controller.
  94  */
  95 static void octeon_i2c_hlc_enable(struct octeon_i2c *i2c)
  96 {
  97         int try = 0;
  98         u64 val;
  99
 100         if (i2c->hlc_enabled)
 101                 return;
 102         i2c->hlc_enabled = true;
 103
 104         while (1) {
 105                 val = octeon_i2c_ctl_read(i2c);
 106                 if (!(val & (TWSI_CTL_STA | TWSI_CTL_STP)))
 107                         break;
 108
 109                 /* clear IFLG event */
 110                 if (val & TWSI_CTL_IFLG)
 111                         octeon_i2c_ctl_write(i2c, TWSI_CTL_ENAB);
 112
 113                 if (try++ > 100) {
 114                         pr_err("%s: giving up\n", __func__);
 115                         break;
 116                 }
 117
 118                 /* spin until any start/stop has finished */
 119                 udelay(10);
 120         }
 121         octeon_i2c_ctl_write(i2c, TWSI_CTL_CE | TWSI_CTL_AAK | TWSI_CTL_ENAB);
 122 }
 123
 124 static void octeon_i2c_hlc_disable(struct octeon_i2c *i2c)
 125 {
 126         if (!i2c->hlc_enabled)
 127                 return;
 128
 129         i2c->hlc_enabled = false;
 130         octeon_i2c_ctl_write(i2c, TWSI_CTL_ENAB);
 131 }
 132
 133 /**
 134  * octeon_i2c_hlc_wait - wait for an HLC operation to complete
 135  * @i2c: The struct octeon_i2c
 136  *
 137  * Returns 0 on success, otherwise -ETIMEDOUT.
 138  */
 139 static int octeon_i2c_hlc_wait(struct octeon_i2c *i2c)
 140 {
 141         int time_left;
 142
 143         /*
 144          * Some cn38xx boards don't assert the irq in the interrupt
 145          * controller. So we must poll for the valid bit change.
 146          */
 147         if (i2c->broken_irq_mode) {
 148                 u64 end = get_jiffies_64() + i2c->adap.timeout;
 149
 150                 while (!octeon_i2c_hlc_test_valid(i2c) &&
 151                        time_before64(get_jiffies_64(), end))
 152                         usleep_range(I2C_OCTEON_EVENT_WAIT / 2, I2C_OCTEON_EVENT_WAIT);
 153
 154                 return octeon_i2c_hlc_test_valid(i2c) ? 0 : -ETIMEDOUT;
 155         }
 156
 157         i2c->hlc_int_enable(i2c);
 158         time_left = wait_event_timeout(i2c->queue,
 159                                        octeon_i2c_hlc_test_valid(i2c),
 160                                        i2c->adap.timeout);
 161         i2c->hlc_int_disable(i2c);
 162         if (!time_left)
 163                 octeon_i2c_hlc_int_clear(i2c);
 164
 165         if (i2c->broken_irq_check && !time_left &&
 166             octeon_i2c_hlc_test_valid(i2c)) {
 167                 dev_err(i2c->dev, "broken irq connection detected, switching to polling mode.\n");
 168                 i2c->broken_irq_mode = true;
 169                 return 0;
 170         }
 171
 172         if (!time_left)
 173                 return -ETIMEDOUT;
 174         return 0;
 175 }
 176
 177 static int octeon_i2c_check_status(struct octeon_i2c *i2c, int final_read)
 178 {
 179         u8 stat;
 180
 181         /*
 182          * This is ugly... in HLC mode the status is not in the status register
 183          * but in the lower 8 bits of SW_TWSI.
 184          */
 185         if (i2c->hlc_enabled)
 186                 stat = __raw_readq(i2c->twsi_base + SW_TWSI(i2c));
 187         else
 188                 stat = octeon_i2c_stat_read(i2c);
 189
 190         switch (stat) {
 191         /* Everything is fine */
 192         case STAT_IDLE:
 193         case STAT_AD2W_ACK:
 194         case STAT_RXADDR_ACK:
 195         case STAT_TXADDR_ACK:
 196         case STAT_TXDATA_ACK:
 197                 return 0;
 198
 199         /* ACK allowed on pre-terminal bytes only */
 200         case STAT_RXDATA_ACK:
 201                 if (!final_read)
 202                         return 0;
 203                 return -EIO;
 204
 205         /* NAK allowed on terminal byte only */
 206         case STAT_RXDATA_NAK:
 207                 if (final_read)
 208                         return 0;
 209                 return -EIO;
 210
 211         /* Arbitration lost */
 212         case STAT_LOST_ARB_38:
 213         case STAT_LOST_ARB_68:
 214         case STAT_LOST_ARB_78:
 215         case STAT_LOST_ARB_B0:
 216                 return -EAGAIN;
 217
 218         /* Being addressed as slave, should back off & listen */
 219         case STAT_SLAVE_60:
 220         case STAT_SLAVE_70:
 221         case STAT_GENDATA_ACK:
 222         case STAT_GENDATA_NAK:
 223                 return -EOPNOTSUPP;
 224
 225         /* Core busy as slave */
 226         case STAT_SLAVE_80:
 227         case STAT_SLAVE_88:
 228         case STAT_SLAVE_A0:
 229         case STAT_SLAVE_A8:
 230         case STAT_SLAVE_LOST:
 231         case STAT_SLAVE_NAK:
 232         case STAT_SLAVE_ACK:
 233                 return -EOPNOTSUPP;
 234
 235         case STAT_TXDATA_NAK:
 236         case STAT_BUS_ERROR:
 237                 return -EIO;
 238         case STAT_TXADDR_NAK:
 239         case STAT_RXADDR_NAK:
 240         case STAT_AD2W_NAK:
 241                 return -ENXIO;
 242         default:
 243                 dev_err(i2c->dev, "unhandled state: %d\n", stat);
 244                 return -EIO;
 245         }
 246 }
 247
 248 static int octeon_i2c_recovery(struct octeon_i2c *i2c)
 249 {
 250         int ret;
 251
 252         ret = i2c_recover_bus(&i2c->adap);
 253         if (ret)
 254                 /* recover failed, try hardware re-init */
 255                 ret = octeon_i2c_init_lowlevel(i2c);
 256         return ret;
 257 }
 258
 259 /**
 260  * octeon_i2c_start - send START to the bus
 261  * @i2c: The struct octeon_i2c
 262  *
 263  * Returns 0 on success, otherwise a negative errno.
 264  */
 265 static int octeon_i2c_start(struct octeon_i2c *i2c)
 266 {
 267         int ret;
 268         u8 stat;
 269
 270         octeon_i2c_hlc_disable(i2c);
 271
 272         octeon_i2c_ctl_write(i2c, TWSI_CTL_ENAB | TWSI_CTL_STA);
 273         ret = octeon_i2c_wait(i2c);
 274         if (ret)
 275                 goto error;
 276
 277         stat = octeon_i2c_stat_read(i2c);
 278         if (stat == STAT_START || stat == STAT_REP_START)
 279                 /* START successful, bail out */
 280                 return 0;
 281
 282 error:
 283         /* START failed, try to recover */
 284         ret = octeon_i2c_recovery(i2c);
 285         return (ret) ? ret : -EAGAIN;
 286 }
 287
 288 /* send STOP to the bus */
 289 static void octeon_i2c_stop(struct octeon_i2c *i2c)
 290 {
 291         octeon_i2c_ctl_write(i2c, TWSI_CTL_ENAB | TWSI_CTL_STP);
 292 }
 293
 294 /**
 295  * octeon_i2c_read - receive data from the bus via low-level controller
 296  * @i2c: The struct octeon_i2c
 297  * @target: Target address
 298  * @data: Pointer to the location to store the data
 299  * @rlength: Length of the data
 300  * @recv_len: flag for length byte
 301  *
 302  * The address is sent over the bus, then the data is read.
 303  *
 304  * Returns 0 on success, otherwise a negative errno.
 305  */
 306 static int octeon_i2c_read(struct octeon_i2c *i2c, int target,
 307                            u8 *data, u16 *rlength, bool recv_len)
 308 {
 309         int i, result, length = *rlength;
 310         bool final_read = false;
 311
 312         octeon_i2c_data_write(i2c, (target << 1) | 1);
 313         octeon_i2c_ctl_write(i2c, TWSI_CTL_ENAB);
 314
 315         result = octeon_i2c_wait(i2c);
 316         if (result)
 317                 return result;
 318
 319         /* address OK ? */
 320         result = octeon_i2c_check_status(i2c, false);
 321         if (result)
 322                 return result;
 323
 324         for (i = 0; i < length; i++) {
 325                 /*
 326                  * For the last byte to receive TWSI_CTL_AAK must not be set.
 327                  *
 328                  * A special case is I2C_M_RECV_LEN where we don't know the
 329                  * additional length yet. If recv_len is set we assume we're
 330                  * not reading the final byte and therefore need to set
 331                  * TWSI_CTL_AAK.
 332                  */
 333                 if ((i + 1 == length) && !(recv_len && i == 0))
 334                         final_read = true;
 335
 336                 /* clear iflg to allow next event */
 337                 if (final_read)
 338                         octeon_i2c_ctl_write(i2c, TWSI_CTL_ENAB);
 339                 else
 340                         octeon_i2c_ctl_write(i2c, TWSI_CTL_ENAB | TWSI_CTL_AAK);
 341
 342                 result = octeon_i2c_wait(i2c);
 343                 if (result)
 344                         return result;
 345
 346                 data[i] = octeon_i2c_data_read(i2c, &result);
 347                 if (result)
 348                         return result;
 349                 if (recv_len && i == 0) {
 350                         if (data[i] > I2C_SMBUS_BLOCK_MAX + 1)
 351                                 return -EPROTO;
 352                         length += data[i];
 353                 }
 354
 355                 result = octeon_i2c_check_status(i2c, final_read);
 356                 if (result)
 357                         return result;
 358         }
 359         *rlength = length;
 360         return 0;
 361 }
 362
 363 /**
 364  * octeon_i2c_write - send data to the bus via low-level controller
 365  * @i2c: The struct octeon_i2c
 366  * @target: Target address
 367  * @data: Pointer to the data to be sent
 368  * @length: Length of the data
 369  *
 370  * The address is sent over the bus, then the data.
 371  *
 372  * Returns 0 on success, otherwise a negative errno.
 373  */
 374 static int octeon_i2c_write(struct octeon_i2c *i2c, int target,
 375                             const u8 *data, int length)
 376 {
 377         int i, result;
 378
 379         octeon_i2c_data_write(i2c, target << 1);
 380         octeon_i2c_ctl_write(i2c, TWSI_CTL_ENAB);
 381
 382         result = octeon_i2c_wait(i2c);
 383         if (result)
 384                 return result;
 385
 386         for (i = 0; i < length; i++) {
 387                 result = octeon_i2c_check_status(i2c, false);
 388                 if (result)
 389                         return result;
 390
 391                 octeon_i2c_data_write(i2c, data[i]);
 392                 octeon_i2c_ctl_write(i2c, TWSI_CTL_ENAB);
 393
 394                 result = octeon_i2c_wait(i2c);
 395                 if (result)
 396                         return result;
 397         }
 398
 399         return 0;
 400 }
 401
 402 /* high-level-controller pure read of up to 8 bytes */
 403 static int octeon_i2c_hlc_read(struct octeon_i2c *i2c, struct i2c_msg *msgs)
 404 {
 405         int i, j, ret = 0;
 406         u64 cmd;
 407
 408         octeon_i2c_hlc_enable(i2c);
 409         octeon_i2c_hlc_int_clear(i2c);
 410
 411         cmd = SW_TWSI_V | SW_TWSI_R | SW_TWSI_SOVR;
 412         /* SIZE */
 413         cmd |= (u64)(msgs[0].len - 1) << SW_TWSI_SIZE_SHIFT;
 414         /* A */
 415         cmd |= (u64)(msgs[0].addr & 0x7full) << SW_TWSI_ADDR_SHIFT;
 416
 417         if (msgs[0].flags & I2C_M_TEN)
 418                 cmd |= SW_TWSI_OP_10;
 419         else
 420                 cmd |= SW_TWSI_OP_7;
 421
 422         octeon_i2c_writeq_flush(cmd, i2c->twsi_base + SW_TWSI(i2c));
 423         ret = octeon_i2c_hlc_wait(i2c);
 424         if (ret)
 425                 goto err;
 426
 427         cmd = __raw_readq(i2c->twsi_base + SW_TWSI(i2c));
 428         if ((cmd & SW_TWSI_R) == 0)
 429                 return octeon_i2c_check_status(i2c, false);
 430
 431         for (i = 0, j = msgs[0].len - 1; i  < msgs[0].len && i < 4; i++, j--)
 432                 msgs[0].buf[j] = (cmd >> (8 * i)) & 0xff;
 433
 434         if (msgs[0].len > 4) {
 435                 cmd = __raw_readq(i2c->twsi_base + SW_TWSI_EXT(i2c));
 436                 for (i = 0; i  < msgs[0].len - 4 && i < 4; i++, j--)
 437                         msgs[0].buf[j] = (cmd >> (8 * i)) & 0xff;
 438         }
 439
 440 err:
 441         return ret;
 442 }
 443
 444 /* high-level-controller pure write of up to 8 bytes */
 445 static int octeon_i2c_hlc_write(struct octeon_i2c *i2c, struct i2c_msg *msgs)
 446 {
 447         int i, j, ret = 0;
 448         u64 cmd;
 449
 450         octeon_i2c_hlc_enable(i2c);
 451         octeon_i2c_hlc_int_clear(i2c);
 452
 453         cmd = SW_TWSI_V | SW_TWSI_SOVR;
 454         /* SIZE */
 455         cmd |= (u64)(msgs[0].len - 1) << SW_TWSI_SIZE_SHIFT;
 456         /* A */
 457         cmd |= (u64)(msgs[0].addr & 0x7full) << SW_TWSI_ADDR_SHIFT;
 458
 459         if (msgs[0].flags & I2C_M_TEN)
 460                 cmd |= SW_TWSI_OP_10;
 461         else
 462                 cmd |= SW_TWSI_OP_7;
 463
 464         for (i = 0, j = msgs[0].len - 1; i  < msgs[0].len && i < 4; i++, j--)
 465                 cmd |= (u64)msgs[0].buf[j] << (8 * i);
 466
 467         if (msgs[0].len > 4) {
 468                 u64 ext = 0;
 469
 470                 for (i = 0; i < msgs[0].len - 4 && i < 4; i++, j--)
 471                         ext |= (u64)msgs[0].buf[j] << (8 * i);
 472                 octeon_i2c_writeq_flush(ext, i2c->twsi_base + SW_TWSI_EXT(i2c));
 473         }
 474
 475         octeon_i2c_writeq_flush(cmd, i2c->twsi_base + SW_TWSI(i2c));
 476         ret = octeon_i2c_hlc_wait(i2c);
 477         if (ret)
 478                 goto err;
 479
 480         cmd = __raw_readq(i2c->twsi_base + SW_TWSI(i2c));
 481         if ((cmd & SW_TWSI_R) == 0)
 482                 return octeon_i2c_check_status(i2c, false);
 483
 484 err:
 485         return ret;
 486 }
 487
 488 /* high-level-controller composite write+read, msg0=addr, msg1=data */
 489 static int octeon_i2c_hlc_comp_read(struct octeon_i2c *i2c, struct i2c_msg *msgs)
 490 {
 491         int i, j, ret = 0;
 492         u64 cmd;
 493
 494         octeon_i2c_hlc_enable(i2c);
 495
 496         cmd = SW_TWSI_V | SW_TWSI_R | SW_TWSI_SOVR;
 497         /* SIZE */
 498         cmd |= (u64)(msgs[1].len - 1) << SW_TWSI_SIZE_SHIFT;
 499         /* A */
 500         cmd |= (u64)(msgs[0].addr & 0x7full) << SW_TWSI_ADDR_SHIFT;
 501
 502         if (msgs[0].flags & I2C_M_TEN)
 503                 cmd |= SW_TWSI_OP_10_IA;
 504         else
 505                 cmd |= SW_TWSI_OP_7_IA;
 506
 507         if (msgs[0].len == 2) {
 508                 u64 ext = 0;
 509
 510                 cmd |= SW_TWSI_EIA;
 511                 ext = (u64)msgs[0].buf[0] << SW_TWSI_IA_SHIFT;
 512                 cmd |= (u64)msgs[0].buf[1] << SW_TWSI_IA_SHIFT;
 513                 octeon_i2c_writeq_flush(ext, i2c->twsi_base + SW_TWSI_EXT(i2c));
 514         } else {
 515                 cmd |= (u64)msgs[0].buf[0] << SW_TWSI_IA_SHIFT;
 516         }
 517
 518         octeon_i2c_hlc_int_clear(i2c);
 519         octeon_i2c_writeq_flush(cmd, i2c->twsi_base + SW_TWSI(i2c));
 520
 521         ret = octeon_i2c_hlc_wait(i2c);
 522         if (ret)
 523                 goto err;
 524
 525         cmd = __raw_readq(i2c->twsi_base + SW_TWSI(i2c));
 526         if ((cmd & SW_TWSI_R) == 0)
 527                 return octeon_i2c_check_status(i2c, false);
 528
 529         for (i = 0, j = msgs[1].len - 1; i  < msgs[1].len && i < 4; i++, j--)
 530                 msgs[1].buf[j] = (cmd >> (8 * i)) & 0xff;
 531
 532         if (msgs[1].len > 4) {
 533                 cmd = __raw_readq(i2c->twsi_base + SW_TWSI_EXT(i2c));
 534                 for (i = 0; i  < msgs[1].len - 4 && i < 4; i++, j--)
 535                         msgs[1].buf[j] = (cmd >> (8 * i)) & 0xff;
 536         }
 537
 538 err:
 539         return ret;
 540 }
 541
 542 /* high-level-controller composite write+write, m[0]len<=2, m[1]len<=8 */
 543 static int octeon_i2c_hlc_comp_write(struct octeon_i2c *i2c, struct i2c_msg *msgs)
 544 {
 545         bool set_ext = false;
 546         int i, j, ret = 0;
 547         u64 cmd, ext = 0;
 548
 549         octeon_i2c_hlc_enable(i2c);
 550
 551         cmd = SW_TWSI_V | SW_TWSI_SOVR;
 552         /* SIZE */
 553         cmd |= (u64)(msgs[1].len - 1) << SW_TWSI_SIZE_SHIFT;
 554         /* A */
 555         cmd |= (u64)(msgs[0].addr & 0x7full) << SW_TWSI_ADDR_SHIFT;
 556
 557         if (msgs[0].flags & I2C_M_TEN)
 558                 cmd |= SW_TWSI_OP_10_IA;
 559         else
 560                 cmd |= SW_TWSI_OP_7_IA;
 561
 562         if (msgs[0].len == 2) {
 563                 cmd |= SW_TWSI_EIA;
 564                 ext |= (u64)msgs[0].buf[0] << SW_TWSI_IA_SHIFT;
 565                 set_ext = true;
 566                 cmd |= (u64)msgs[0].buf[1] << SW_TWSI_IA_SHIFT;
 567         } else {
 568                 cmd |= (u64)msgs[0].buf[0] << SW_TWSI_IA_SHIFT;
 569         }
 570
 571         for (i = 0, j = msgs[1].len - 1; i  < msgs[1].len && i < 4; i++, j--)
 572                 cmd |= (u64)msgs[1].buf[j] << (8 * i);
 573
 574         if (msgs[1].len > 4) {
 575                 for (i = 0; i < msgs[1].len - 4 && i < 4; i++, j--)
 576                         ext |= (u64)msgs[1].buf[j] << (8 * i);
 577                 set_ext = true;
 578         }
 579         if (set_ext)
 580                 octeon_i2c_writeq_flush(ext, i2c->twsi_base + SW_TWSI_EXT(i2c));
 581
 582         octeon_i2c_hlc_int_clear(i2c);
 583         octeon_i2c_writeq_flush(cmd, i2c->twsi_base + SW_TWSI(i2c));
 584
 585         ret = octeon_i2c_hlc_wait(i2c);
 586         if (ret)
 587                 goto err;
 588
 589         cmd = __raw_readq(i2c->twsi_base + SW_TWSI(i2c));
 590         if ((cmd & SW_TWSI_R) == 0)
 591                 return octeon_i2c_check_status(i2c, false);
 592
 593 err:
 594         return ret;
 595 }
 596
 597 /**
 598  * octeon_i2c_xfer - The driver's master_xfer function
 599  * @adap: Pointer to the i2c_adapter structure
 600  * @msgs: Pointer to the messages to be processed
 601  * @num: Length of the MSGS array
 602  *
 603  * Returns the number of messages processed, or a negative errno on failure.
 604  */
 605 int octeon_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
 606 {
 607         struct octeon_i2c *i2c = i2c_get_adapdata(adap);
 608         int i, ret = 0;
 609
 610         if (num == 1) {
 611                 if (msgs[0].len > 0 && msgs[0].len <= 8) {
 612                         if (msgs[0].flags & I2C_M_RD)
 613                                 ret = octeon_i2c_hlc_read(i2c, msgs);
 614                         else
 615                                 ret = octeon_i2c_hlc_write(i2c, msgs);
 616                         goto out;
 617                 }
 618         } else if (num == 2) {
 619                 if ((msgs[0].flags & I2C_M_RD) == 0 &&
 620                     (msgs[1].flags & I2C_M_RECV_LEN) == 0 &&
 621                     msgs[0].len > 0 && msgs[0].len <= 2 &&
 622                     msgs[1].len > 0 && msgs[1].len <= 8 &&
 623                     msgs[0].addr == msgs[1].addr) {
 624                         if (msgs[1].flags & I2C_M_RD)
 625                                 ret = octeon_i2c_hlc_comp_read(i2c, msgs);
 626                         else
 627                                 ret = octeon_i2c_hlc_comp_write(i2c, msgs);
 628                         goto out;
 629                 }
 630         }
 631
 632         for (i = 0; ret == 0 && i < num; i++) {
 633                 struct i2c_msg *pmsg = &msgs[i];
 634
 635                 /* zero-length messages are not supported */
 636                 if (!pmsg->len) {
 637                         ret = -EOPNOTSUPP;
 638                         break;
 639                 }
 640
 641                 ret = octeon_i2c_start(i2c);
 642                 if (ret)
 643                         return ret;
 644
 645                 if (pmsg->flags & I2C_M_RD)
 646                         ret = octeon_i2c_read(i2c, pmsg->addr, pmsg->buf,
 647                                               &pmsg->len, pmsg->flags & I2C_M_RECV_LEN);
 648                 else
 649                         ret = octeon_i2c_write(i2c, pmsg->addr, pmsg->buf,
 650                                                pmsg->len);
 651         }
 652         octeon_i2c_stop(i2c);
 653 out:
 654         return (ret != 0) ? ret : num;
 655 }
 656
 657 /* calculate and set clock divisors */
 658 void octeon_i2c_set_clock(struct octeon_i2c *i2c)
 659 {
 660         int tclk, thp_base, inc, thp_idx, mdiv_idx, ndiv_idx, foscl, diff;
 661         int thp = 0x18, mdiv = 2, ndiv = 0, delta_hz = 1000000;
 662
 663         for (ndiv_idx = 0; ndiv_idx < 8 && delta_hz != 0; ndiv_idx++) {
 664                 /*
 665                  * An mdiv value of less than 2 seems to not work well
 666                  * with ds1337 RTCs, so we constrain it to larger values.
 667                  */
 668                 for (mdiv_idx = 15; mdiv_idx >= 2 && delta_hz != 0; mdiv_idx--) {
 669                         /*
 670                          * For given ndiv and mdiv values check the
 671                          * two closest thp values.
 672                          */
 673                         tclk = i2c->twsi_freq * (mdiv_idx + 1) * 10;
 674                         tclk *= (1 << ndiv_idx);
 675                         thp_base = (i2c->sys_freq / (tclk * 2)) - 1;
 676
 677                         for (inc = 0; inc <= 1; inc++) {
 678                                 thp_idx = thp_base + inc;
 679                                 if (thp_idx < 5 || thp_idx > 0xff)
 680                                         continue;
 681
 682                                 foscl = i2c->sys_freq / (2 * (thp_idx + 1));
 683                                 foscl = foscl / (1 << ndiv_idx);
 684                                 foscl = foscl / (mdiv_idx + 1) / 10;
 685                                 diff = abs(foscl - i2c->twsi_freq);
 686                                 if (diff < delta_hz) {
 687                                         delta_hz = diff;
 688                                         thp = thp_idx;
 689                                         mdiv = mdiv_idx;
 690                                         ndiv = ndiv_idx;
 691                                 }
 692                         }
 693                 }
 694         }
 695         octeon_i2c_reg_write(i2c, SW_TWSI_OP_TWSI_CLK, thp);
 696         octeon_i2c_reg_write(i2c, SW_TWSI_EOP_TWSI_CLKCTL, (mdiv << 3) | ndiv);
 697 }
 698
 699 int octeon_i2c_init_lowlevel(struct octeon_i2c *i2c)
 700 {
 701         u8 status = 0;
 702         int tries;
 703
 704         /* reset controller */
 705         octeon_i2c_reg_write(i2c, SW_TWSI_EOP_TWSI_RST, 0);
 706
 707         for (tries = 10; tries && status != STAT_IDLE; tries--) {
 708                 udelay(1);
 709                 status = octeon_i2c_stat_read(i2c);
 710                 if (status == STAT_IDLE)
 711                         break;
 712         }
 713
 714         if (status != STAT_IDLE) {
 715                 dev_err(i2c->dev, "%s: TWSI_RST failed! (0x%x)\n",
 716                         __func__, status);
 717                 return -EIO;
 718         }
 719
 720         /* toggle twice to force both teardowns */
 721         octeon_i2c_hlc_enable(i2c);
 722         octeon_i2c_hlc_disable(i2c);
 723         return 0;
 724 }
 725
 726 static int octeon_i2c_get_scl(struct i2c_adapter *adap)
 727 {
 728         struct octeon_i2c *i2c = i2c_get_adapdata(adap);
 729         u64 state;
 730
 731         state = octeon_i2c_read_int(i2c);
 732         return state & TWSI_INT_SCL;
 733 }
 734
 735 static void octeon_i2c_set_scl(struct i2c_adapter *adap, int val)
 736 {
 737         struct octeon_i2c *i2c = i2c_get_adapdata(adap);
 738
 739         octeon_i2c_write_int(i2c, val ? 0 : TWSI_INT_SCL_OVR);
 740 }
 741
 742 static int octeon_i2c_get_sda(struct i2c_adapter *adap)
 743 {
 744         struct octeon_i2c *i2c = i2c_get_adapdata(adap);
 745         u64 state;
 746
 747         state = octeon_i2c_read_int(i2c);
 748         return state & TWSI_INT_SDA;
 749 }
 750
 751 static void octeon_i2c_prepare_recovery(struct i2c_adapter *adap)
 752 {
 753         struct octeon_i2c *i2c = i2c_get_adapdata(adap);
 754
 755         octeon_i2c_hlc_disable(i2c);
 756         octeon_i2c_reg_write(i2c, SW_TWSI_EOP_TWSI_RST, 0);
 757         /* wait for software reset to settle */
 758         udelay(5);
 759
 760         /*
 761          * Bring control register to a good state regardless
 762          * of HLC state.
 763          */
 764         octeon_i2c_ctl_write(i2c, TWSI_CTL_ENAB);
 765
 766         octeon_i2c_write_int(i2c, 0);
 767 }
 768
 769 static void octeon_i2c_unprepare_recovery(struct i2c_adapter *adap)
 770 {
 771         struct octeon_i2c *i2c = i2c_get_adapdata(adap);
 772
 773         /*
 774          * Generate STOP to finish the unfinished transaction.
 775          * Can't generate STOP via the TWSI CTL register
 776          * since it could bring the TWSI controller into an inoperable state.
 777          */
 778         octeon_i2c_write_int(i2c, TWSI_INT_SDA_OVR | TWSI_INT_SCL_OVR);
 779         udelay(5);
 780         octeon_i2c_write_int(i2c, TWSI_INT_SDA_OVR);
 781         udelay(5);
 782         octeon_i2c_write_int(i2c, 0);
 783 }
 784
 785 struct i2c_bus_recovery_info octeon_i2c_recovery_info = {
 786         .recover_bus = i2c_generic_scl_recovery,
 787         .get_scl = octeon_i2c_get_scl,
 788         .set_scl = octeon_i2c_set_scl,
 789         .get_sda = octeon_i2c_get_sda,
 790         .prepare_recovery = octeon_i2c_prepare_recovery,
 791         .unprepare_recovery = octeon_i2c_unprepare_recovery,
 792 };