1 /* 2 * A sensor driver for the magnetometer AK8975. 3 * 4 * Magnetic compass sensor driver for monitoring magnetic flux information. 5 * 6 * Copyright (c) 2010, NVIDIA Corporation. 7 * 8 * This program is free software; you can redistribute it and/or modify 9 * it under the terms of the GNU General Public License as published by 10 * the Free Software Foundation; either version 2 of the License, or 11 * (at your option) any later version. 12 * 13 * This program is distributed in the hope that it will be useful, but WITHOUT 14 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 15 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for 16 * more details. 17 * 18 * You should have received a copy of the GNU General Public License along 19 * with this program; if not, write to the Free Software Foundation, Inc., 20 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. 21 */ 22 23 #include <linux/module.h> 24 #include <linux/kernel.h> 25 #include <linux/slab.h> 26 #include <linux/i2c.h> 27 #include <linux/interrupt.h> 28 #include <linux/err.h> 29 #include <linux/mutex.h> 30 #include <linux/delay.h> 31 #include <linux/bitops.h> 32 #include <linux/gpio.h> 33 #include <linux/of_gpio.h> 34 #include <linux/acpi.h> 35 36 #include <linux/iio/iio.h> 37 #include <linux/iio/sysfs.h> 38 /* 39 * Register definitions, as well as various shifts and masks to get at the 40 * individual fields of the registers. 41 */ 42 #define AK8975_REG_WIA 0x00 43 #define AK8975_DEVICE_ID 0x48 44 45 #define AK8975_REG_INFO 0x01 46 47 #define AK8975_REG_ST1 0x02 48 #define AK8975_REG_ST1_DRDY_SHIFT 0 49 #define AK8975_REG_ST1_DRDY_MASK (1 << AK8975_REG_ST1_DRDY_SHIFT) 50 51 #define AK8975_REG_HXL 0x03 52 #define AK8975_REG_HXH 0x04 53 #define AK8975_REG_HYL 0x05 54 #define AK8975_REG_HYH 0x06 55 #define AK8975_REG_HZL 0x07 56 #define AK8975_REG_HZH 0x08 57 #define AK8975_REG_ST2 0x09 58 #define AK8975_REG_ST2_DERR_SHIFT 2 59 #define AK8975_REG_ST2_DERR_MASK (1 << AK8975_REG_ST2_DERR_SHIFT) 60 61 #define AK8975_REG_ST2_HOFL_SHIFT 3 62 #define AK8975_REG_ST2_HOFL_MASK (1 << AK8975_REG_ST2_HOFL_SHIFT) 63 64 #define AK8975_REG_CNTL 0x0A 65 #define AK8975_REG_CNTL_MODE_SHIFT 0 66 #define AK8975_REG_CNTL_MODE_MASK (0xF << AK8975_REG_CNTL_MODE_SHIFT) 67 #define AK8975_REG_CNTL_MODE_POWER_DOWN 0 68 #define AK8975_REG_CNTL_MODE_ONCE 1 69 #define AK8975_REG_CNTL_MODE_SELF_TEST 8 70 #define AK8975_REG_CNTL_MODE_FUSE_ROM 0xF 71 72 #define AK8975_REG_RSVC 0x0B 73 #define AK8975_REG_ASTC 0x0C 74 #define AK8975_REG_TS1 0x0D 75 #define AK8975_REG_TS2 0x0E 76 #define AK8975_REG_I2CDIS 0x0F 77 #define AK8975_REG_ASAX 0x10 78 #define AK8975_REG_ASAY 0x11 79 #define AK8975_REG_ASAZ 0x12 80 81 #define AK8975_MAX_REGS AK8975_REG_ASAZ 82 83 /* 84 * Miscellaneous values. 85 */ 86 #define AK8975_MAX_CONVERSION_TIMEOUT 500 87 #define AK8975_CONVERSION_DONE_POLL_TIME 10 88 #define AK8975_DATA_READY_TIMEOUT ((100*HZ)/1000) 89 #define RAW_TO_GAUSS_8975(asa) ((((asa) + 128) * 3000) / 256) 90 #define RAW_TO_GAUSS_8963(asa) ((((asa) + 128) * 6000) / 256) 91 92 /* Compatible Asahi Kasei Compass parts */ 93 enum asahi_compass_chipset { 94 AK8975, 95 AK8963, 96 }; 97 98 /* 99 * Per-instance context data for the device. 100 */ 101 struct ak8975_data { 102 struct i2c_client *client; 103 struct attribute_group attrs; 104 struct mutex lock; 105 u8 asa[3]; 106 long raw_to_gauss[3]; 107 u8 reg_cache[AK8975_MAX_REGS]; 108 int eoc_gpio; 109 int eoc_irq; 110 wait_queue_head_t data_ready_queue; 111 unsigned long flags; 112 enum asahi_compass_chipset chipset; 113 }; 114 115 static const int ak8975_index_to_reg[] = { 116 AK8975_REG_HXL, AK8975_REG_HYL, AK8975_REG_HZL, 117 }; 118 119 /* 120 * Helper function to write to the I2C device's registers. 121 */ 122 static int ak8975_write_data(struct i2c_client *client, 123 u8 reg, u8 val, u8 mask, u8 shift) 124 { 125 struct iio_dev *indio_dev = i2c_get_clientdata(client); 126 struct ak8975_data *data = iio_priv(indio_dev); 127 u8 regval; 128 int ret; 129 130 regval = (data->reg_cache[reg] & ~mask) | (val << shift); 131 ret = i2c_smbus_write_byte_data(client, reg, regval); 132 if (ret < 0) { 133 dev_err(&client->dev, "Write to device fails status %x\n", ret); 134 return ret; 135 } 136 data->reg_cache[reg] = regval; 137 138 return 0; 139 } 140 141 /* 142 * Handle data ready irq 143 */ 144 static irqreturn_t ak8975_irq_handler(int irq, void *data) 145 { 146 struct ak8975_data *ak8975 = data; 147 148 set_bit(0, &ak8975->flags); 149 wake_up(&ak8975->data_ready_queue); 150 151 return IRQ_HANDLED; 152 } 153 154 /* 155 * Install data ready interrupt handler 156 */ 157 static int ak8975_setup_irq(struct ak8975_data *data) 158 { 159 struct i2c_client *client = data->client; 160 int rc; 161 int irq; 162 163 if (client->irq) 164 irq = client->irq; 165 else 166 irq = gpio_to_irq(data->eoc_gpio); 167 168 rc = request_irq(irq, ak8975_irq_handler, 169 IRQF_TRIGGER_RISING | IRQF_ONESHOT, 170 dev_name(&client->dev), data); 171 if (rc < 0) { 172 dev_err(&client->dev, 173 "irq %d request failed, (gpio %d): %d\n", 174 irq, data->eoc_gpio, rc); 175 return rc; 176 } 177 178 init_waitqueue_head(&data->data_ready_queue); 179 clear_bit(0, &data->flags); 180 data->eoc_irq = irq; 181 182 return rc; 183 } 184 185 186 /* 187 * Perform some start-of-day setup, including reading the asa calibration 188 * values and caching them. 189 */ 190 static int ak8975_setup(struct i2c_client *client) 191 { 192 struct iio_dev *indio_dev = i2c_get_clientdata(client); 193 struct ak8975_data *data = iio_priv(indio_dev); 194 u8 device_id; 195 int ret; 196 197 /* Confirm that the device we're talking to is really an AK8975. */ 198 ret = i2c_smbus_read_byte_data(client, AK8975_REG_WIA); 199 if (ret < 0) { 200 dev_err(&client->dev, "Error reading WIA\n"); 201 return ret; 202 } 203 device_id = ret; 204 if (device_id != AK8975_DEVICE_ID) { 205 dev_err(&client->dev, "Device ak8975 not found\n"); 206 return -ENODEV; 207 } 208 209 /* Write the fused rom access mode. */ 210 ret = ak8975_write_data(client, 211 AK8975_REG_CNTL, 212 AK8975_REG_CNTL_MODE_FUSE_ROM, 213 AK8975_REG_CNTL_MODE_MASK, 214 AK8975_REG_CNTL_MODE_SHIFT); 215 if (ret < 0) { 216 dev_err(&client->dev, "Error in setting fuse access mode\n"); 217 return ret; 218 } 219 220 /* Get asa data and store in the device data. */ 221 ret = i2c_smbus_read_i2c_block_data(client, AK8975_REG_ASAX, 222 3, data->asa); 223 if (ret < 0) { 224 dev_err(&client->dev, "Not able to read asa data\n"); 225 return ret; 226 } 227 228 /* After reading fuse ROM data set power-down mode */ 229 ret = ak8975_write_data(client, 230 AK8975_REG_CNTL, 231 AK8975_REG_CNTL_MODE_POWER_DOWN, 232 AK8975_REG_CNTL_MODE_MASK, 233 AK8975_REG_CNTL_MODE_SHIFT); 234 235 if (data->eoc_gpio > 0 || client->irq) { 236 ret = ak8975_setup_irq(data); 237 if (ret < 0) { 238 dev_err(&client->dev, 239 "Error setting data ready interrupt\n"); 240 return ret; 241 } 242 } 243 244 if (ret < 0) { 245 dev_err(&client->dev, "Error in setting power-down mode\n"); 246 return ret; 247 } 248 249 /* 250 * Precalculate scale factor (in Gauss units) for each axis and 251 * store in the device data. 252 * 253 * This scale factor is axis-dependent, and is derived from 3 calibration 254 * factors ASA(x), ASA(y), and ASA(z). 255 * 256 * These ASA values are read from the sensor device at start of day, and 257 * cached in the device context struct. 258 * 259 * Adjusting the flux value with the sensitivity adjustment value should be 260 * done via the following formula: 261 * 262 * Hadj = H * ( ( ( (ASA-128)*0.5 ) / 128 ) + 1 ) 263 * 264 * where H is the raw value, ASA is the sensitivity adjustment, and Hadj 265 * is the resultant adjusted value. 266 * 267 * We reduce the formula to: 268 * 269 * Hadj = H * (ASA + 128) / 256 270 * 271 * H is in the range of -4096 to 4095. The magnetometer has a range of 272 * +-1229uT. To go from the raw value to uT is: 273 * 274 * HuT = H * 1229/4096, or roughly, 3/10. 275 * 276 * Since 1uT = 0.01 gauss, our final scale factor becomes: 277 * 278 * Hadj = H * ((ASA + 128) / 256) * 3/10 * 1/100 279 * Hadj = H * ((ASA + 128) * 0.003) / 256 280 * 281 * Since ASA doesn't change, we cache the resultant scale factor into the 282 * device context in ak8975_setup(). 283 */ 284 if (data->chipset == AK8963) { 285 /* 286 * H range is +-8190 and magnetometer range is +-4912. 287 * So HuT using the above explanation for 8975, 288 * 4912/8190 = ~ 6/10. 289 * So the Hadj should use 6/10 instead of 3/10. 290 */ 291 data->raw_to_gauss[0] = RAW_TO_GAUSS_8963(data->asa[0]); 292 data->raw_to_gauss[1] = RAW_TO_GAUSS_8963(data->asa[1]); 293 data->raw_to_gauss[2] = RAW_TO_GAUSS_8963(data->asa[2]); 294 } else { 295 data->raw_to_gauss[0] = RAW_TO_GAUSS_8975(data->asa[0]); 296 data->raw_to_gauss[1] = RAW_TO_GAUSS_8975(data->asa[1]); 297 data->raw_to_gauss[2] = RAW_TO_GAUSS_8975(data->asa[2]); 298 } 299 300 return 0; 301 } 302 303 static int wait_conversion_complete_gpio(struct ak8975_data *data) 304 { 305 struct i2c_client *client = data->client; 306 u32 timeout_ms = AK8975_MAX_CONVERSION_TIMEOUT; 307 int ret; 308 309 /* Wait for the conversion to complete. */ 310 while (timeout_ms) { 311 msleep(AK8975_CONVERSION_DONE_POLL_TIME); 312 if (gpio_get_value(data->eoc_gpio)) 313 break; 314 timeout_ms -= AK8975_CONVERSION_DONE_POLL_TIME; 315 } 316 if (!timeout_ms) { 317 dev_err(&client->dev, "Conversion timeout happened\n"); 318 return -EINVAL; 319 } 320 321 ret = i2c_smbus_read_byte_data(client, AK8975_REG_ST1); 322 if (ret < 0) 323 dev_err(&client->dev, "Error in reading ST1\n"); 324 325 return ret; 326 } 327 328 static int wait_conversion_complete_polled(struct ak8975_data *data) 329 { 330 struct i2c_client *client = data->client; 331 u8 read_status; 332 u32 timeout_ms = AK8975_MAX_CONVERSION_TIMEOUT; 333 int ret; 334 335 /* Wait for the conversion to complete. */ 336 while (timeout_ms) { 337 msleep(AK8975_CONVERSION_DONE_POLL_TIME); 338 ret = i2c_smbus_read_byte_data(client, AK8975_REG_ST1); 339 if (ret < 0) { 340 dev_err(&client->dev, "Error in reading ST1\n"); 341 return ret; 342 } 343 read_status = ret; 344 if (read_status) 345 break; 346 timeout_ms -= AK8975_CONVERSION_DONE_POLL_TIME; 347 } 348 if (!timeout_ms) { 349 dev_err(&client->dev, "Conversion timeout happened\n"); 350 return -EINVAL; 351 } 352 353 return read_status; 354 } 355 356 /* Returns 0 if the end of conversion interrupt occured or -ETIME otherwise */ 357 static int wait_conversion_complete_interrupt(struct ak8975_data *data) 358 { 359 int ret; 360 361 ret = wait_event_timeout(data->data_ready_queue, 362 test_bit(0, &data->flags), 363 AK8975_DATA_READY_TIMEOUT); 364 clear_bit(0, &data->flags); 365 366 return ret > 0 ? 0 : -ETIME; 367 } 368 369 /* 370 * Emits the raw flux value for the x, y, or z axis. 371 */ 372 static int ak8975_read_axis(struct iio_dev *indio_dev, int index, int *val) 373 { 374 struct ak8975_data *data = iio_priv(indio_dev); 375 struct i2c_client *client = data->client; 376 u16 meas_reg; 377 s16 raw; 378 int ret; 379 380 mutex_lock(&data->lock); 381 382 /* Set up the device for taking a sample. */ 383 ret = ak8975_write_data(client, 384 AK8975_REG_CNTL, 385 AK8975_REG_CNTL_MODE_ONCE, 386 AK8975_REG_CNTL_MODE_MASK, 387 AK8975_REG_CNTL_MODE_SHIFT); 388 if (ret < 0) { 389 dev_err(&client->dev, "Error in setting operating mode\n"); 390 goto exit; 391 } 392 393 /* Wait for the conversion to complete. */ 394 if (data->eoc_irq) 395 ret = wait_conversion_complete_interrupt(data); 396 else if (gpio_is_valid(data->eoc_gpio)) 397 ret = wait_conversion_complete_gpio(data); 398 else 399 ret = wait_conversion_complete_polled(data); 400 if (ret < 0) 401 goto exit; 402 403 /* This will be executed only for non-interrupt based waiting case */ 404 if (ret & AK8975_REG_ST1_DRDY_MASK) { 405 ret = i2c_smbus_read_byte_data(client, AK8975_REG_ST2); 406 if (ret < 0) { 407 dev_err(&client->dev, "Error in reading ST2\n"); 408 goto exit; 409 } 410 if (ret & (AK8975_REG_ST2_DERR_MASK | 411 AK8975_REG_ST2_HOFL_MASK)) { 412 dev_err(&client->dev, "ST2 status error 0x%x\n", ret); 413 ret = -EINVAL; 414 goto exit; 415 } 416 } 417 418 /* Read the flux value from the appropriate register 419 (the register is specified in the iio device attributes). */ 420 ret = i2c_smbus_read_word_data(client, ak8975_index_to_reg[index]); 421 if (ret < 0) { 422 dev_err(&client->dev, "Read axis data fails\n"); 423 goto exit; 424 } 425 meas_reg = ret; 426 427 mutex_unlock(&data->lock); 428 429 /* Endian conversion of the measured values. */ 430 raw = (s16) (le16_to_cpu(meas_reg)); 431 432 /* Clamp to valid range. */ 433 raw = clamp_t(s16, raw, -4096, 4095); 434 *val = raw; 435 return IIO_VAL_INT; 436 437 exit: 438 mutex_unlock(&data->lock); 439 return ret; 440 } 441 442 static int ak8975_read_raw(struct iio_dev *indio_dev, 443 struct iio_chan_spec const *chan, 444 int *val, int *val2, 445 long mask) 446 { 447 struct ak8975_data *data = iio_priv(indio_dev); 448 449 switch (mask) { 450 case IIO_CHAN_INFO_RAW: 451 return ak8975_read_axis(indio_dev, chan->address, val); 452 case IIO_CHAN_INFO_SCALE: 453 *val = 0; 454 *val2 = data->raw_to_gauss[chan->address]; 455 return IIO_VAL_INT_PLUS_MICRO; 456 } 457 return -EINVAL; 458 } 459 460 #define AK8975_CHANNEL(axis, index) \ 461 { \ 462 .type = IIO_MAGN, \ 463 .modified = 1, \ 464 .channel2 = IIO_MOD_##axis, \ 465 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \ 466 BIT(IIO_CHAN_INFO_SCALE), \ 467 .address = index, \ 468 } 469 470 static const struct iio_chan_spec ak8975_channels[] = { 471 AK8975_CHANNEL(X, 0), AK8975_CHANNEL(Y, 1), AK8975_CHANNEL(Z, 2), 472 }; 473 474 static const struct iio_info ak8975_info = { 475 .read_raw = &ak8975_read_raw, 476 .driver_module = THIS_MODULE, 477 }; 478 479 static const struct acpi_device_id ak_acpi_match[] = { 480 {"AK8975", AK8975}, 481 {"AK8963", AK8963}, 482 {"INVN6500", AK8963}, 483 { }, 484 }; 485 MODULE_DEVICE_TABLE(acpi, ak_acpi_match); 486 487 static char *ak8975_match_acpi_device(struct device *dev, 488 enum asahi_compass_chipset *chipset) 489 { 490 const struct acpi_device_id *id; 491 492 id = acpi_match_device(dev->driver->acpi_match_table, dev); 493 if (!id) 494 return NULL; 495 *chipset = (int)id->driver_data; 496 497 return (char *)dev_name(dev); 498 } 499 500 static int ak8975_probe(struct i2c_client *client, 501 const struct i2c_device_id *id) 502 { 503 struct ak8975_data *data; 504 struct iio_dev *indio_dev; 505 int eoc_gpio; 506 int err; 507 char *name = NULL; 508 509 /* Grab and set up the supplied GPIO. */ 510 if (client->dev.platform_data) 511 eoc_gpio = *(int *)(client->dev.platform_data); 512 else if (client->dev.of_node) 513 eoc_gpio = of_get_gpio(client->dev.of_node, 0); 514 else 515 eoc_gpio = -1; 516 517 if (eoc_gpio == -EPROBE_DEFER) 518 return -EPROBE_DEFER; 519 520 /* We may not have a GPIO based IRQ to scan, that is fine, we will 521 poll if so */ 522 if (gpio_is_valid(eoc_gpio)) { 523 err = gpio_request_one(eoc_gpio, GPIOF_IN, "ak_8975"); 524 if (err < 0) { 525 dev_err(&client->dev, 526 "failed to request GPIO %d, error %d\n", 527 eoc_gpio, err); 528 goto exit; 529 } 530 } 531 532 /* Register with IIO */ 533 indio_dev = iio_device_alloc(sizeof(*data)); 534 if (indio_dev == NULL) { 535 err = -ENOMEM; 536 goto exit_gpio; 537 } 538 data = iio_priv(indio_dev); 539 i2c_set_clientdata(client, indio_dev); 540 541 data->client = client; 542 data->eoc_gpio = eoc_gpio; 543 data->eoc_irq = 0; 544 545 /* id will be NULL when enumerated via ACPI */ 546 if (id) { 547 data->chipset = 548 (enum asahi_compass_chipset)(id->driver_data); 549 name = (char *) id->name; 550 } else if (ACPI_HANDLE(&client->dev)) 551 name = ak8975_match_acpi_device(&client->dev, &data->chipset); 552 else { 553 err = -ENOSYS; 554 goto exit_free_iio; 555 } 556 dev_dbg(&client->dev, "Asahi compass chip %s\n", name); 557 558 /* Perform some basic start-of-day setup of the device. */ 559 err = ak8975_setup(client); 560 if (err < 0) { 561 dev_err(&client->dev, "AK8975 initialization fails\n"); 562 goto exit_free_iio; 563 } 564 565 data->client = client; 566 mutex_init(&data->lock); 567 data->eoc_gpio = eoc_gpio; 568 indio_dev->dev.parent = &client->dev; 569 indio_dev->channels = ak8975_channels; 570 indio_dev->num_channels = ARRAY_SIZE(ak8975_channels); 571 indio_dev->info = &ak8975_info; 572 indio_dev->modes = INDIO_DIRECT_MODE; 573 indio_dev->name = name; 574 err = iio_device_register(indio_dev); 575 if (err < 0) 576 goto exit_free_iio; 577 578 return 0; 579 580 exit_free_iio: 581 iio_device_free(indio_dev); 582 if (data->eoc_irq) 583 free_irq(data->eoc_irq, data); 584 exit_gpio: 585 if (gpio_is_valid(eoc_gpio)) 586 gpio_free(eoc_gpio); 587 exit: 588 return err; 589 } 590 591 static int ak8975_remove(struct i2c_client *client) 592 { 593 struct iio_dev *indio_dev = i2c_get_clientdata(client); 594 struct ak8975_data *data = iio_priv(indio_dev); 595 596 iio_device_unregister(indio_dev); 597 598 if (data->eoc_irq) 599 free_irq(data->eoc_irq, data); 600 601 if (gpio_is_valid(data->eoc_gpio)) 602 gpio_free(data->eoc_gpio); 603 604 iio_device_free(indio_dev); 605 606 return 0; 607 } 608 609 static const struct i2c_device_id ak8975_id[] = { 610 {"ak8975", AK8975}, 611 {"ak8963", AK8963}, 612 {} 613 }; 614 615 MODULE_DEVICE_TABLE(i2c, ak8975_id); 616 617 static const struct of_device_id ak8975_of_match[] = { 618 { .compatible = "asahi-kasei,ak8975", }, 619 { .compatible = "ak8975", }, 620 { } 621 }; 622 MODULE_DEVICE_TABLE(of, ak8975_of_match); 623 624 static struct i2c_driver ak8975_driver = { 625 .driver = { 626 .name = "ak8975", 627 .of_match_table = ak8975_of_match, 628 .acpi_match_table = ACPI_PTR(ak_acpi_match), 629 }, 630 .probe = ak8975_probe, 631 .remove = ak8975_remove, 632 .id_table = ak8975_id, 633 }; 634 module_i2c_driver(ak8975_driver); 635 636 MODULE_AUTHOR("Laxman Dewangan <ldewangan@nvidia.com>"); 637 MODULE_DESCRIPTION("AK8975 magnetometer driver"); 638 MODULE_LICENSE("GPL"); 639