1 /* 2 * i2c-ocores.c: I2C bus driver for OpenCores I2C controller 3 * (https://opencores.org/project/i2c/overview) 4 * 5 * Peter Korsgaard <peter@korsgaard.com> 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/platform_data/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, i2c_8bit_addr_from_msg(i2c->msg)); 226 oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_START); 227 228 if (wait_event_timeout(i2c->wait, (i2c->state == STATE_ERROR) || 229 (i2c->state == STATE_DONE), HZ)) 230 return (i2c->state == STATE_DONE) ? num : -EIO; 231 else 232 return -ETIMEDOUT; 233 } 234 235 static int ocores_init(struct device *dev, struct ocores_i2c *i2c) 236 { 237 int prescale; 238 int diff; 239 u8 ctrl = oc_getreg(i2c, OCI2C_CONTROL); 240 241 /* make sure the device is disabled */ 242 oc_setreg(i2c, OCI2C_CONTROL, ctrl & ~(OCI2C_CTRL_EN|OCI2C_CTRL_IEN)); 243 244 prescale = (i2c->ip_clock_khz / (5 * i2c->bus_clock_khz)) - 1; 245 prescale = clamp(prescale, 0, 0xffff); 246 247 diff = i2c->ip_clock_khz / (5 * (prescale + 1)) - i2c->bus_clock_khz; 248 if (abs(diff) > i2c->bus_clock_khz / 10) { 249 dev_err(dev, 250 "Unsupported clock settings: core: %d KHz, bus: %d KHz\n", 251 i2c->ip_clock_khz, i2c->bus_clock_khz); 252 return -EINVAL; 253 } 254 255 oc_setreg(i2c, OCI2C_PRELOW, prescale & 0xff); 256 oc_setreg(i2c, OCI2C_PREHIGH, prescale >> 8); 257 258 /* Init the device */ 259 oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_IACK); 260 oc_setreg(i2c, OCI2C_CONTROL, ctrl | OCI2C_CTRL_IEN | OCI2C_CTRL_EN); 261 262 return 0; 263 } 264 265 266 static u32 ocores_func(struct i2c_adapter *adap) 267 { 268 return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL; 269 } 270 271 static const struct i2c_algorithm ocores_algorithm = { 272 .master_xfer = ocores_xfer, 273 .functionality = ocores_func, 274 }; 275 276 static const struct i2c_adapter ocores_adapter = { 277 .owner = THIS_MODULE, 278 .name = "i2c-ocores", 279 .class = I2C_CLASS_DEPRECATED, 280 .algo = &ocores_algorithm, 281 }; 282 283 static const struct of_device_id ocores_i2c_match[] = { 284 { 285 .compatible = "opencores,i2c-ocores", 286 .data = (void *)TYPE_OCORES, 287 }, 288 { 289 .compatible = "aeroflexgaisler,i2cmst", 290 .data = (void *)TYPE_GRLIB, 291 }, 292 {}, 293 }; 294 MODULE_DEVICE_TABLE(of, ocores_i2c_match); 295 296 #ifdef CONFIG_OF 297 /* Read and write functions for the GRLIB port of the controller. Registers are 298 * 32-bit big endian and the PRELOW and PREHIGH registers are merged into one 299 * register. The subsequent registers has their offset decreased accordingly. */ 300 static u8 oc_getreg_grlib(struct ocores_i2c *i2c, int reg) 301 { 302 u32 rd; 303 int rreg = reg; 304 if (reg != OCI2C_PRELOW) 305 rreg--; 306 rd = ioread32be(i2c->base + (rreg << i2c->reg_shift)); 307 if (reg == OCI2C_PREHIGH) 308 return (u8)(rd >> 8); 309 else 310 return (u8)rd; 311 } 312 313 static void oc_setreg_grlib(struct ocores_i2c *i2c, int reg, u8 value) 314 { 315 u32 curr, wr; 316 int rreg = reg; 317 if (reg != OCI2C_PRELOW) 318 rreg--; 319 if (reg == OCI2C_PRELOW || reg == OCI2C_PREHIGH) { 320 curr = ioread32be(i2c->base + (rreg << i2c->reg_shift)); 321 if (reg == OCI2C_PRELOW) 322 wr = (curr & 0xff00) | value; 323 else 324 wr = (((u32)value) << 8) | (curr & 0xff); 325 } else { 326 wr = value; 327 } 328 iowrite32be(wr, i2c->base + (rreg << i2c->reg_shift)); 329 } 330 331 static int ocores_i2c_of_probe(struct platform_device *pdev, 332 struct ocores_i2c *i2c) 333 { 334 struct device_node *np = pdev->dev.of_node; 335 const struct of_device_id *match; 336 u32 val; 337 u32 clock_frequency; 338 bool clock_frequency_present; 339 340 if (of_property_read_u32(np, "reg-shift", &i2c->reg_shift)) { 341 /* no 'reg-shift', check for deprecated 'regstep' */ 342 if (!of_property_read_u32(np, "regstep", &val)) { 343 if (!is_power_of_2(val)) { 344 dev_err(&pdev->dev, "invalid regstep %d\n", 345 val); 346 return -EINVAL; 347 } 348 i2c->reg_shift = ilog2(val); 349 dev_warn(&pdev->dev, 350 "regstep property deprecated, use reg-shift\n"); 351 } 352 } 353 354 clock_frequency_present = !of_property_read_u32(np, "clock-frequency", 355 &clock_frequency); 356 i2c->bus_clock_khz = 100; 357 358 i2c->clk = devm_clk_get(&pdev->dev, NULL); 359 360 if (!IS_ERR(i2c->clk)) { 361 int ret = clk_prepare_enable(i2c->clk); 362 363 if (ret) { 364 dev_err(&pdev->dev, 365 "clk_prepare_enable failed: %d\n", ret); 366 return ret; 367 } 368 i2c->ip_clock_khz = clk_get_rate(i2c->clk) / 1000; 369 if (clock_frequency_present) 370 i2c->bus_clock_khz = clock_frequency / 1000; 371 } 372 373 if (i2c->ip_clock_khz == 0) { 374 if (of_property_read_u32(np, "opencores,ip-clock-frequency", 375 &val)) { 376 if (!clock_frequency_present) { 377 dev_err(&pdev->dev, 378 "Missing required parameter 'opencores,ip-clock-frequency'\n"); 379 clk_disable_unprepare(i2c->clk); 380 return -ENODEV; 381 } 382 i2c->ip_clock_khz = clock_frequency / 1000; 383 dev_warn(&pdev->dev, 384 "Deprecated usage of the 'clock-frequency' property, please update to 'opencores,ip-clock-frequency'\n"); 385 } else { 386 i2c->ip_clock_khz = val / 1000; 387 if (clock_frequency_present) 388 i2c->bus_clock_khz = clock_frequency / 1000; 389 } 390 } 391 392 of_property_read_u32(pdev->dev.of_node, "reg-io-width", 393 &i2c->reg_io_width); 394 395 match = of_match_node(ocores_i2c_match, pdev->dev.of_node); 396 if (match && (long)match->data == TYPE_GRLIB) { 397 dev_dbg(&pdev->dev, "GRLIB variant of i2c-ocores\n"); 398 i2c->setreg = oc_setreg_grlib; 399 i2c->getreg = oc_getreg_grlib; 400 } 401 402 return 0; 403 } 404 #else 405 #define ocores_i2c_of_probe(pdev,i2c) -ENODEV 406 #endif 407 408 static int ocores_i2c_probe(struct platform_device *pdev) 409 { 410 struct ocores_i2c *i2c; 411 struct ocores_i2c_platform_data *pdata; 412 struct resource *res; 413 int irq; 414 int ret; 415 int i; 416 417 irq = platform_get_irq(pdev, 0); 418 if (irq < 0) 419 return irq; 420 421 i2c = devm_kzalloc(&pdev->dev, sizeof(*i2c), GFP_KERNEL); 422 if (!i2c) 423 return -ENOMEM; 424 425 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 426 i2c->base = devm_ioremap_resource(&pdev->dev, res); 427 if (IS_ERR(i2c->base)) 428 return PTR_ERR(i2c->base); 429 430 pdata = dev_get_platdata(&pdev->dev); 431 if (pdata) { 432 i2c->reg_shift = pdata->reg_shift; 433 i2c->reg_io_width = pdata->reg_io_width; 434 i2c->ip_clock_khz = pdata->clock_khz; 435 i2c->bus_clock_khz = 100; 436 } else { 437 ret = ocores_i2c_of_probe(pdev, i2c); 438 if (ret) 439 return ret; 440 } 441 442 if (i2c->reg_io_width == 0) 443 i2c->reg_io_width = 1; /* Set to default value */ 444 445 if (!i2c->setreg || !i2c->getreg) { 446 bool be = pdata ? pdata->big_endian : 447 of_device_is_big_endian(pdev->dev.of_node); 448 449 switch (i2c->reg_io_width) { 450 case 1: 451 i2c->setreg = oc_setreg_8; 452 i2c->getreg = oc_getreg_8; 453 break; 454 455 case 2: 456 i2c->setreg = be ? oc_setreg_16be : oc_setreg_16; 457 i2c->getreg = be ? oc_getreg_16be : oc_getreg_16; 458 break; 459 460 case 4: 461 i2c->setreg = be ? oc_setreg_32be : oc_setreg_32; 462 i2c->getreg = be ? oc_getreg_32be : oc_getreg_32; 463 break; 464 465 default: 466 dev_err(&pdev->dev, "Unsupported I/O width (%d)\n", 467 i2c->reg_io_width); 468 ret = -EINVAL; 469 goto err_clk; 470 } 471 } 472 473 ret = ocores_init(&pdev->dev, i2c); 474 if (ret) 475 goto err_clk; 476 477 init_waitqueue_head(&i2c->wait); 478 ret = devm_request_irq(&pdev->dev, irq, ocores_isr, 0, 479 pdev->name, i2c); 480 if (ret) { 481 dev_err(&pdev->dev, "Cannot claim IRQ\n"); 482 goto err_clk; 483 } 484 485 /* hook up driver to tree */ 486 platform_set_drvdata(pdev, i2c); 487 i2c->adap = ocores_adapter; 488 i2c_set_adapdata(&i2c->adap, i2c); 489 i2c->adap.dev.parent = &pdev->dev; 490 i2c->adap.dev.of_node = pdev->dev.of_node; 491 492 /* add i2c adapter to i2c tree */ 493 ret = i2c_add_adapter(&i2c->adap); 494 if (ret) 495 goto err_clk; 496 497 /* add in known devices to the bus */ 498 if (pdata) { 499 for (i = 0; i < pdata->num_devices; i++) 500 i2c_new_device(&i2c->adap, pdata->devices + i); 501 } 502 503 return 0; 504 505 err_clk: 506 clk_disable_unprepare(i2c->clk); 507 return ret; 508 } 509 510 static int ocores_i2c_remove(struct platform_device *pdev) 511 { 512 struct ocores_i2c *i2c = platform_get_drvdata(pdev); 513 514 /* disable i2c logic */ 515 oc_setreg(i2c, OCI2C_CONTROL, oc_getreg(i2c, OCI2C_CONTROL) 516 & ~(OCI2C_CTRL_EN|OCI2C_CTRL_IEN)); 517 518 /* remove adapter & data */ 519 i2c_del_adapter(&i2c->adap); 520 521 if (!IS_ERR(i2c->clk)) 522 clk_disable_unprepare(i2c->clk); 523 524 return 0; 525 } 526 527 #ifdef CONFIG_PM_SLEEP 528 static int ocores_i2c_suspend(struct device *dev) 529 { 530 struct ocores_i2c *i2c = dev_get_drvdata(dev); 531 u8 ctrl = oc_getreg(i2c, OCI2C_CONTROL); 532 533 /* make sure the device is disabled */ 534 oc_setreg(i2c, OCI2C_CONTROL, ctrl & ~(OCI2C_CTRL_EN|OCI2C_CTRL_IEN)); 535 536 if (!IS_ERR(i2c->clk)) 537 clk_disable_unprepare(i2c->clk); 538 return 0; 539 } 540 541 static int ocores_i2c_resume(struct device *dev) 542 { 543 struct ocores_i2c *i2c = dev_get_drvdata(dev); 544 545 if (!IS_ERR(i2c->clk)) { 546 unsigned long rate; 547 int ret = clk_prepare_enable(i2c->clk); 548 549 if (ret) { 550 dev_err(dev, 551 "clk_prepare_enable failed: %d\n", ret); 552 return ret; 553 } 554 rate = clk_get_rate(i2c->clk) / 1000; 555 if (rate) 556 i2c->ip_clock_khz = rate; 557 } 558 return ocores_init(dev, i2c); 559 } 560 561 static SIMPLE_DEV_PM_OPS(ocores_i2c_pm, ocores_i2c_suspend, ocores_i2c_resume); 562 #define OCORES_I2C_PM (&ocores_i2c_pm) 563 #else 564 #define OCORES_I2C_PM NULL 565 #endif 566 567 static struct platform_driver ocores_i2c_driver = { 568 .probe = ocores_i2c_probe, 569 .remove = ocores_i2c_remove, 570 .driver = { 571 .name = "ocores-i2c", 572 .of_match_table = ocores_i2c_match, 573 .pm = OCORES_I2C_PM, 574 }, 575 }; 576 577 module_platform_driver(ocores_i2c_driver); 578 579 MODULE_AUTHOR("Peter Korsgaard <peter@korsgaard.com>"); 580 MODULE_DESCRIPTION("OpenCores I2C bus driver"); 581 MODULE_LICENSE("GPL"); 582 MODULE_ALIAS("platform:ocores-i2c"); 583