drivers/i2c/busses/i2c-ocores.c

   1 /*
   2  * i2c-ocores.c: I2C bus driver for OpenCores I2C controller
   3  * (http://www.opencores.org/projects.cgi/web/i2c/overview).
   4  *
   5  * Peter Korsgaard <jacmet@sunsite.dk>
   6  *
   7  * Support for the GRLIB port of the controller by
   8  * Andreas Larsson <andreas@gaisler.com>
   9  *
  10  * This file is licensed under the terms of the GNU General Public License
  11  * version 2.  This program is licensed "as is" without any warranty of any
  12  * kind, whether express or implied.
  13  */
  14
  15 #include <linux/clk.h>
  16 #include <linux/err.h>
  17 #include <linux/kernel.h>
  18 #include <linux/module.h>
  19 #include <linux/errno.h>
  20 #include <linux/platform_device.h>
  21 #include <linux/i2c.h>
  22 #include <linux/interrupt.h>
  23 #include <linux/wait.h>
  24 #include <linux/i2c-ocores.h>
  25 #include <linux/slab.h>
  26 #include <linux/io.h>
  27 #include <linux/log2.h>
  28
  29 struct ocores_i2c {
  30         void __iomem *base;
  31         u32 reg_shift;
  32         u32 reg_io_width;
  33         wait_queue_head_t wait;
  34         struct i2c_adapter adap;
  35         struct i2c_msg *msg;
  36         int pos;
  37         int nmsgs;
  38         int state; /* see STATE_ */
  39         struct clk *clk;
  40         int ip_clock_khz;
  41         int bus_clock_khz;
  42         void (*setreg)(struct ocores_i2c *i2c, int reg, u8 value);
  43         u8 (*getreg)(struct ocores_i2c *i2c, int reg);
  44 };
  45
  46 /* registers */
  47 #define OCI2C_PRELOW            0
  48 #define OCI2C_PREHIGH           1
  49 #define OCI2C_CONTROL           2
  50 #define OCI2C_DATA              3
  51 #define OCI2C_CMD               4 /* write only */
  52 #define OCI2C_STATUS            4 /* read only, same address as OCI2C_CMD */
  53
  54 #define OCI2C_CTRL_IEN          0x40
  55 #define OCI2C_CTRL_EN           0x80
  56
  57 #define OCI2C_CMD_START         0x91
  58 #define OCI2C_CMD_STOP          0x41
  59 #define OCI2C_CMD_READ          0x21
  60 #define OCI2C_CMD_WRITE         0x11
  61 #define OCI2C_CMD_READ_ACK      0x21
  62 #define OCI2C_CMD_READ_NACK     0x29
  63 #define OCI2C_CMD_IACK          0x01
  64
  65 #define OCI2C_STAT_IF           0x01
  66 #define OCI2C_STAT_TIP          0x02
  67 #define OCI2C_STAT_ARBLOST      0x20
  68 #define OCI2C_STAT_BUSY         0x40
  69 #define OCI2C_STAT_NACK         0x80
  70
  71 #define STATE_DONE              0
  72 #define STATE_START             1
  73 #define STATE_WRITE             2
  74 #define STATE_READ              3
  75 #define STATE_ERROR             4
  76
  77 #define TYPE_OCORES             0
  78 #define TYPE_GRLIB              1
  79
  80 static void oc_setreg_8(struct ocores_i2c *i2c, int reg, u8 value)
  81 {
  82         iowrite8(value, i2c->base + (reg << i2c->reg_shift));
  83 }
  84
  85 static void oc_setreg_16(struct ocores_i2c *i2c, int reg, u8 value)
  86 {
  87         iowrite16(value, i2c->base + (reg << i2c->reg_shift));
  88 }
  89
  90 static void oc_setreg_32(struct ocores_i2c *i2c, int reg, u8 value)
  91 {
  92         iowrite32(value, i2c->base + (reg << i2c->reg_shift));
  93 }
  94
  95 static void oc_setreg_16be(struct ocores_i2c *i2c, int reg, u8 value)
  96 {
  97         iowrite16be(value, i2c->base + (reg << i2c->reg_shift));
  98 }
  99
 100 static void oc_setreg_32be(struct ocores_i2c *i2c, int reg, u8 value)
 101 {
 102         iowrite32be(value, i2c->base + (reg << i2c->reg_shift));
 103 }
 104
 105 static inline u8 oc_getreg_8(struct ocores_i2c *i2c, int reg)
 106 {
 107         return ioread8(i2c->base + (reg << i2c->reg_shift));
 108 }
 109
 110 static inline u8 oc_getreg_16(struct ocores_i2c *i2c, int reg)
 111 {
 112         return ioread16(i2c->base + (reg << i2c->reg_shift));
 113 }
 114
 115 static inline u8 oc_getreg_32(struct ocores_i2c *i2c, int reg)
 116 {
 117         return ioread32(i2c->base + (reg << i2c->reg_shift));
 118 }
 119
 120 static inline u8 oc_getreg_16be(struct ocores_i2c *i2c, int reg)
 121 {
 122         return ioread16be(i2c->base + (reg << i2c->reg_shift));
 123 }
 124
 125 static inline u8 oc_getreg_32be(struct ocores_i2c *i2c, int reg)
 126 {
 127         return ioread32be(i2c->base + (reg << i2c->reg_shift));
 128 }
 129
 130 static inline void oc_setreg(struct ocores_i2c *i2c, int reg, u8 value)
 131 {
 132         i2c->setreg(i2c, reg, value);
 133 }
 134
 135 static inline u8 oc_getreg(struct ocores_i2c *i2c, int reg)
 136 {
 137         return i2c->getreg(i2c, reg);
 138 }
 139
 140 static void ocores_process(struct ocores_i2c *i2c)
 141 {
 142         struct i2c_msg *msg = i2c->msg;
 143         u8 stat = oc_getreg(i2c, OCI2C_STATUS);
 144
 145         if ((i2c->state == STATE_DONE) || (i2c->state == STATE_ERROR)) {
 146                 /* stop has been sent */
 147                 oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_IACK);
 148                 wake_up(&i2c->wait);
 149                 return;
 150         }
 151
 152         /* error? */
 153         if (stat & OCI2C_STAT_ARBLOST) {
 154                 i2c->state = STATE_ERROR;
 155                 oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_STOP);
 156                 return;
 157         }
 158
 159         if ((i2c->state == STATE_START) || (i2c->state == STATE_WRITE)) {
 160                 i2c->state =
 161                         (msg->flags & I2C_M_RD) ? STATE_READ : STATE_WRITE;
 162
 163                 if (stat & OCI2C_STAT_NACK) {
 164                         i2c->state = STATE_ERROR;
 165                         oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_STOP);
 166                         return;
 167                 }
 168         } else
 169                 msg->buf[i2c->pos++] = oc_getreg(i2c, OCI2C_DATA);
 170
 171         /* end of msg? */
 172         if (i2c->pos == msg->len) {
 173                 i2c->nmsgs--;
 174                 i2c->msg++;
 175                 i2c->pos = 0;
 176                 msg = i2c->msg;
 177
 178                 if (i2c->nmsgs) {       /* end? */
 179                         /* send start? */
 180                         if (!(msg->flags & I2C_M_NOSTART)) {
 181                                 u8 addr = i2c_8bit_addr_from_msg(msg);
 182
 183                                 i2c->state = STATE_START;
 184
 185                                 oc_setreg(i2c, OCI2C_DATA, addr);
 186                                 oc_setreg(i2c, OCI2C_CMD,  OCI2C_CMD_START);
 187                                 return;
 188                         } else
 189                                 i2c->state = (msg->flags & I2C_M_RD)
 190                                         ? STATE_READ : STATE_WRITE;
 191                 } else {
 192                         i2c->state = STATE_DONE;
 193                         oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_STOP);
 194                         return;
 195                 }
 196         }
 197
 198         if (i2c->state == STATE_READ) {
 199                 oc_setreg(i2c, OCI2C_CMD, i2c->pos == (msg->len-1) ?
 200                           OCI2C_CMD_READ_NACK : OCI2C_CMD_READ_ACK);
 201         } else {
 202                 oc_setreg(i2c, OCI2C_DATA, msg->buf[i2c->pos++]);
 203                 oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_WRITE);
 204         }
 205 }
 206
 207 static irqreturn_t ocores_isr(int irq, void *dev_id)
 208 {
 209         struct ocores_i2c *i2c = dev_id;
 210
 211         ocores_process(i2c);
 212
 213         return IRQ_HANDLED;
 214 }
 215
 216 static int ocores_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
 217 {
 218         struct ocores_i2c *i2c = i2c_get_adapdata(adap);
 219
 220         i2c->msg = msgs;
 221         i2c->pos = 0;
 222         i2c->nmsgs = num;
 223         i2c->state = STATE_START;
 224
 225         oc_setreg(i2c, OCI2C_DATA,
 226                         (i2c->msg->addr << 1) |
 227                         ((i2c->msg->flags & I2C_M_RD) ? 1:0));
 228
 229         oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_START);
 230
 231         if (wait_event_timeout(i2c->wait, (i2c->state == STATE_ERROR) ||
 232                                (i2c->state == STATE_DONE), HZ))
 233                 return (i2c->state == STATE_DONE) ? num : -EIO;
 234         else
 235                 return -ETIMEDOUT;
 236 }
 237
 238 static int ocores_init(struct device *dev, struct ocores_i2c *i2c)
 239 {
 240         int prescale;
 241         int diff;
 242         u8 ctrl = oc_getreg(i2c, OCI2C_CONTROL);
 243
 244         /* make sure the device is disabled */
 245         oc_setreg(i2c, OCI2C_CONTROL, ctrl & ~(OCI2C_CTRL_EN|OCI2C_CTRL_IEN));
 246
 247         prescale = (i2c->ip_clock_khz / (5 * i2c->bus_clock_khz)) - 1;
 248         prescale = clamp(prescale, 0, 0xffff);
 249
 250         diff = i2c->ip_clock_khz / (5 * (prescale + 1)) - i2c->bus_clock_khz;
 251         if (abs(diff) > i2c->bus_clock_khz / 10) {
 252                 dev_err(dev,
 253                         "Unsupported clock settings: core: %d KHz, bus: %d KHz\n",
 254                         i2c->ip_clock_khz, i2c->bus_clock_khz);
 255                 return -EINVAL;
 256         }
 257
 258         oc_setreg(i2c, OCI2C_PRELOW, prescale & 0xff);
 259         oc_setreg(i2c, OCI2C_PREHIGH, prescale >> 8);
 260
 261         /* Init the device */
 262         oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_IACK);
 263         oc_setreg(i2c, OCI2C_CONTROL, ctrl | OCI2C_CTRL_IEN | OCI2C_CTRL_EN);
 264
 265         return 0;
 266 }
 267
 268
 269 static u32 ocores_func(struct i2c_adapter *adap)
 270 {
 271         return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
 272 }
 273
 274 static const struct i2c_algorithm ocores_algorithm = {
 275         .master_xfer = ocores_xfer,
 276         .functionality = ocores_func,
 277 };
 278
 279 static struct i2c_adapter ocores_adapter = {
 280         .owner = THIS_MODULE,
 281         .name = "i2c-ocores",
 282         .class = I2C_CLASS_DEPRECATED,
 283         .algo = &ocores_algorithm,
 284 };
 285
 286 static const struct of_device_id ocores_i2c_match[] = {
 287         {
 288                 .compatible = "opencores,i2c-ocores",
 289                 .data = (void *)TYPE_OCORES,
 290         },
 291         {
 292                 .compatible = "aeroflexgaisler,i2cmst",
 293                 .data = (void *)TYPE_GRLIB,
 294         },
 295         {},
 296 };
 297 MODULE_DEVICE_TABLE(of, ocores_i2c_match);
 298
 299 #ifdef CONFIG_OF
 300 /* Read and write functions for the GRLIB port of the controller. Registers are
 301  * 32-bit big endian and the PRELOW and PREHIGH registers are merged into one
 302  * register. The subsequent registers has their offset decreased accordingly. */
 303 static u8 oc_getreg_grlib(struct ocores_i2c *i2c, int reg)
 304 {
 305         u32 rd;
 306         int rreg = reg;
 307         if (reg != OCI2C_PRELOW)
 308                 rreg--;
 309         rd = ioread32be(i2c->base + (rreg << i2c->reg_shift));
 310         if (reg == OCI2C_PREHIGH)
 311                 return (u8)(rd >> 8);
 312         else
 313                 return (u8)rd;
 314 }
 315
 316 static void oc_setreg_grlib(struct ocores_i2c *i2c, int reg, u8 value)
 317 {
 318         u32 curr, wr;
 319         int rreg = reg;
 320         if (reg != OCI2C_PRELOW)
 321                 rreg--;
 322         if (reg == OCI2C_PRELOW || reg == OCI2C_PREHIGH) {
 323                 curr = ioread32be(i2c->base + (rreg << i2c->reg_shift));
 324                 if (reg == OCI2C_PRELOW)
 325                         wr = (curr & 0xff00) | value;
 326                 else
 327                         wr = (((u32)value) << 8) | (curr & 0xff);
 328         } else {
 329                 wr = value;
 330         }
 331         iowrite32be(wr, i2c->base + (rreg << i2c->reg_shift));
 332 }
 333
 334 static int ocores_i2c_of_probe(struct platform_device *pdev,
 335                                 struct ocores_i2c *i2c)
 336 {
 337         struct device_node *np = pdev->dev.of_node;
 338         const struct of_device_id *match;
 339         u32 val;
 340         u32 clock_frequency;
 341         bool clock_frequency_present;
 342
 343         if (of_property_read_u32(np, "reg-shift", &i2c->reg_shift)) {
 344                 /* no 'reg-shift', check for deprecated 'regstep' */
 345                 if (!of_property_read_u32(np, "regstep", &val)) {
 346                         if (!is_power_of_2(val)) {
 347                                 dev_err(&pdev->dev, "invalid regstep %d\n",
 348                                         val);
 349                                 return -EINVAL;
 350                         }
 351                         i2c->reg_shift = ilog2(val);
 352                         dev_warn(&pdev->dev,
 353                                 "regstep property deprecated, use reg-shift\n");
 354                 }
 355         }
 356
 357         clock_frequency_present = !of_property_read_u32(np, "clock-frequency",
 358                                                         &clock_frequency);
 359         i2c->bus_clock_khz = 100;
 360
 361         i2c->clk = devm_clk_get(&pdev->dev, NULL);
 362
 363         if (!IS_ERR(i2c->clk)) {
 364                 int ret = clk_prepare_enable(i2c->clk);
 365
 366                 if (ret) {
 367                         dev_err(&pdev->dev,
 368                                 "clk_prepare_enable failed: %d\n", ret);
 369                         return ret;
 370                 }
 371                 i2c->ip_clock_khz = clk_get_rate(i2c->clk) / 1000;
 372                 if (clock_frequency_present)
 373                         i2c->bus_clock_khz = clock_frequency / 1000;
 374         }
 375
 376         if (i2c->ip_clock_khz == 0) {
 377                 if (of_property_read_u32(np, "opencores,ip-clock-frequency",
 378                                                 &val)) {
 379                         if (!clock_frequency_present) {
 380                                 dev_err(&pdev->dev,
 381                                         "Missing required parameter 'opencores,ip-clock-frequency'\n");
 382                                 clk_disable_unprepare(i2c->clk);
 383                                 return -ENODEV;
 384                         }
 385                         i2c->ip_clock_khz = clock_frequency / 1000;
 386                         dev_warn(&pdev->dev,
 387                                  "Deprecated usage of the 'clock-frequency' property, please update to 'opencores,ip-clock-frequency'\n");
 388                 } else {
 389                         i2c->ip_clock_khz = val / 1000;
 390                         if (clock_frequency_present)
 391                                 i2c->bus_clock_khz = clock_frequency / 1000;
 392                 }
 393         }
 394
 395         of_property_read_u32(pdev->dev.of_node, "reg-io-width",
 396                                 &i2c->reg_io_width);
 397
 398         match = of_match_node(ocores_i2c_match, pdev->dev.of_node);
 399         if (match && (long)match->data == TYPE_GRLIB) {
 400                 dev_dbg(&pdev->dev, "GRLIB variant of i2c-ocores\n");
 401                 i2c->setreg = oc_setreg_grlib;
 402                 i2c->getreg = oc_getreg_grlib;
 403         }
 404
 405         return 0;
 406 }
 407 #else
 408 #define ocores_i2c_of_probe(pdev,i2c) -ENODEV
 409 #endif
 410
 411 static int ocores_i2c_probe(struct platform_device *pdev)
 412 {
 413         struct ocores_i2c *i2c;
 414         struct ocores_i2c_platform_data *pdata;
 415         struct resource *res;
 416         int irq;
 417         int ret;
 418         int i;
 419
 420         irq = platform_get_irq(pdev, 0);
 421         if (irq < 0)
 422                 return irq;
 423
 424         i2c = devm_kzalloc(&pdev->dev, sizeof(*i2c), GFP_KERNEL);
 425         if (!i2c)
 426                 return -ENOMEM;
 427
 428         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 429         i2c->base = devm_ioremap_resource(&pdev->dev, res);
 430         if (IS_ERR(i2c->base))
 431                 return PTR_ERR(i2c->base);
 432
 433         pdata = dev_get_platdata(&pdev->dev);
 434         if (pdata) {
 435                 i2c->reg_shift = pdata->reg_shift;
 436                 i2c->reg_io_width = pdata->reg_io_width;
 437                 i2c->ip_clock_khz = pdata->clock_khz;
 438                 i2c->bus_clock_khz = 100;
 439         } else {
 440                 ret = ocores_i2c_of_probe(pdev, i2c);
 441                 if (ret)
 442                         return ret;
 443         }
 444
 445         if (i2c->reg_io_width == 0)
 446                 i2c->reg_io_width = 1; /* Set to default value */
 447
 448         if (!i2c->setreg || !i2c->getreg) {
 449                 bool be = pdata ? pdata->big_endian :
 450                         of_device_is_big_endian(pdev->dev.of_node);
 451
 452                 switch (i2c->reg_io_width) {
 453                 case 1:
 454                         i2c->setreg = oc_setreg_8;
 455                         i2c->getreg = oc_getreg_8;
 456                         break;
 457
 458                 case 2:
 459                         i2c->setreg = be ? oc_setreg_16be : oc_setreg_16;
 460                         i2c->getreg = be ? oc_getreg_16be : oc_getreg_16;
 461                         break;
 462
 463                 case 4:
 464                         i2c->setreg = be ? oc_setreg_32be : oc_setreg_32;
 465                         i2c->getreg = be ? oc_getreg_32be : oc_getreg_32;
 466                         break;
 467
 468                 default:
 469                         dev_err(&pdev->dev, "Unsupported I/O width (%d)\n",
 470                                 i2c->reg_io_width);
 471                         ret = -EINVAL;
 472                         goto err_clk;
 473                 }
 474         }
 475
 476         ret = ocores_init(&pdev->dev, i2c);
 477         if (ret)
 478                 goto err_clk;
 479
 480         init_waitqueue_head(&i2c->wait);
 481         ret = devm_request_irq(&pdev->dev, irq, ocores_isr, 0,
 482                                pdev->name, i2c);
 483         if (ret) {
 484                 dev_err(&pdev->dev, "Cannot claim IRQ\n");
 485                 goto err_clk;
 486         }
 487
 488         /* hook up driver to tree */
 489         platform_set_drvdata(pdev, i2c);
 490         i2c->adap = ocores_adapter;
 491         i2c_set_adapdata(&i2c->adap, i2c);
 492         i2c->adap.dev.parent = &pdev->dev;
 493         i2c->adap.dev.of_node = pdev->dev.of_node;
 494
 495         /* add i2c adapter to i2c tree */
 496         ret = i2c_add_adapter(&i2c->adap);
 497         if (ret) {
 498                 dev_err(&pdev->dev, "Failed to add adapter\n");
 499                 goto err_clk;
 500         }
 501
 502         /* add in known devices to the bus */
 503         if (pdata) {
 504                 for (i = 0; i < pdata->num_devices; i++)
 505                         i2c_new_device(&i2c->adap, pdata->devices + i);
 506         }
 507
 508         return 0;
 509
 510 err_clk:
 511         clk_disable_unprepare(i2c->clk);
 512         return ret;
 513 }
 514
 515 static int ocores_i2c_remove(struct platform_device *pdev)
 516 {
 517         struct ocores_i2c *i2c = platform_get_drvdata(pdev);
 518
 519         /* disable i2c logic */
 520         oc_setreg(i2c, OCI2C_CONTROL, oc_getreg(i2c, OCI2C_CONTROL)
 521                   & ~(OCI2C_CTRL_EN|OCI2C_CTRL_IEN));
 522
 523         /* remove adapter & data */
 524         i2c_del_adapter(&i2c->adap);
 525
 526         if (!IS_ERR(i2c->clk))
 527                 clk_disable_unprepare(i2c->clk);
 528
 529         return 0;
 530 }
 531
 532 #ifdef CONFIG_PM_SLEEP
 533 static int ocores_i2c_suspend(struct device *dev)
 534 {
 535         struct ocores_i2c *i2c = dev_get_drvdata(dev);
 536         u8 ctrl = oc_getreg(i2c, OCI2C_CONTROL);
 537
 538         /* make sure the device is disabled */
 539         oc_setreg(i2c, OCI2C_CONTROL, ctrl & ~(OCI2C_CTRL_EN|OCI2C_CTRL_IEN));
 540
 541         if (!IS_ERR(i2c->clk))
 542                 clk_disable_unprepare(i2c->clk);
 543         return 0;
 544 }
 545
 546 static int ocores_i2c_resume(struct device *dev)
 547 {
 548         struct ocores_i2c *i2c = dev_get_drvdata(dev);
 549
 550         if (!IS_ERR(i2c->clk)) {
 551                 unsigned long rate;
 552                 int ret = clk_prepare_enable(i2c->clk);
 553
 554                 if (ret) {
 555                         dev_err(dev,
 556                                 "clk_prepare_enable failed: %d\n", ret);
 557                         return ret;
 558                 }
 559                 rate = clk_get_rate(i2c->clk) / 1000;
 560                 if (rate)
 561                         i2c->ip_clock_khz = rate;
 562         }
 563         return ocores_init(dev, i2c);
 564 }
 565
 566 static SIMPLE_DEV_PM_OPS(ocores_i2c_pm, ocores_i2c_suspend, ocores_i2c_resume);
 567 #define OCORES_I2C_PM   (&ocores_i2c_pm)
 568 #else
 569 #define OCORES_I2C_PM   NULL
 570 #endif
 571
 572 static struct platform_driver ocores_i2c_driver = {
 573         .probe   = ocores_i2c_probe,
 574         .remove  = ocores_i2c_remove,
 575         .driver  = {
 576                 .name = "ocores-i2c",
 577                 .of_match_table = ocores_i2c_match,
 578                 .pm = OCORES_I2C_PM,
 579         },
 580 };
 581
 582 module_platform_driver(ocores_i2c_driver);
 583
 584 MODULE_AUTHOR("Peter Korsgaard <jacmet@sunsite.dk>");
 585 MODULE_DESCRIPTION("OpenCores I2C bus driver");
 586 MODULE_LICENSE("GPL");
 587 MODULE_ALIAS("platform:ocores-i2c");