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 = devm_request_irq(&client->dev, 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 int ret; 377 378 mutex_lock(&data->lock); 379 380 /* Set up the device for taking a sample. */ 381 ret = ak8975_write_data(client, 382 AK8975_REG_CNTL, 383 AK8975_REG_CNTL_MODE_ONCE, 384 AK8975_REG_CNTL_MODE_MASK, 385 AK8975_REG_CNTL_MODE_SHIFT); 386 if (ret < 0) { 387 dev_err(&client->dev, "Error in setting operating mode\n"); 388 goto exit; 389 } 390 391 /* Wait for the conversion to complete. */ 392 if (data->eoc_irq) 393 ret = wait_conversion_complete_interrupt(data); 394 else if (gpio_is_valid(data->eoc_gpio)) 395 ret = wait_conversion_complete_gpio(data); 396 else 397 ret = wait_conversion_complete_polled(data); 398 if (ret < 0) 399 goto exit; 400 401 /* This will be executed only for non-interrupt based waiting case */ 402 if (ret & AK8975_REG_ST1_DRDY_MASK) { 403 ret = i2c_smbus_read_byte_data(client, AK8975_REG_ST2); 404 if (ret < 0) { 405 dev_err(&client->dev, "Error in reading ST2\n"); 406 goto exit; 407 } 408 if (ret & (AK8975_REG_ST2_DERR_MASK | 409 AK8975_REG_ST2_HOFL_MASK)) { 410 dev_err(&client->dev, "ST2 status error 0x%x\n", ret); 411 ret = -EINVAL; 412 goto exit; 413 } 414 } 415 416 /* Read the flux value from the appropriate register 417 (the register is specified in the iio device attributes). */ 418 ret = i2c_smbus_read_word_data(client, ak8975_index_to_reg[index]); 419 if (ret < 0) { 420 dev_err(&client->dev, "Read axis data fails\n"); 421 goto exit; 422 } 423 424 mutex_unlock(&data->lock); 425 426 /* Clamp to valid range. */ 427 *val = clamp_t(s16, ret, -4096, 4095); 428 return IIO_VAL_INT; 429 430 exit: 431 mutex_unlock(&data->lock); 432 return ret; 433 } 434 435 static int ak8975_read_raw(struct iio_dev *indio_dev, 436 struct iio_chan_spec const *chan, 437 int *val, int *val2, 438 long mask) 439 { 440 struct ak8975_data *data = iio_priv(indio_dev); 441 442 switch (mask) { 443 case IIO_CHAN_INFO_RAW: 444 return ak8975_read_axis(indio_dev, chan->address, val); 445 case IIO_CHAN_INFO_SCALE: 446 *val = 0; 447 *val2 = data->raw_to_gauss[chan->address]; 448 return IIO_VAL_INT_PLUS_MICRO; 449 } 450 return -EINVAL; 451 } 452 453 #define AK8975_CHANNEL(axis, index) \ 454 { \ 455 .type = IIO_MAGN, \ 456 .modified = 1, \ 457 .channel2 = IIO_MOD_##axis, \ 458 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \ 459 BIT(IIO_CHAN_INFO_SCALE), \ 460 .address = index, \ 461 } 462 463 static const struct iio_chan_spec ak8975_channels[] = { 464 AK8975_CHANNEL(X, 0), AK8975_CHANNEL(Y, 1), AK8975_CHANNEL(Z, 2), 465 }; 466 467 static const struct iio_info ak8975_info = { 468 .read_raw = &ak8975_read_raw, 469 .driver_module = THIS_MODULE, 470 }; 471 472 static const struct acpi_device_id ak_acpi_match[] = { 473 {"AK8975", AK8975}, 474 {"AK8963", AK8963}, 475 {"INVN6500", AK8963}, 476 { }, 477 }; 478 MODULE_DEVICE_TABLE(acpi, ak_acpi_match); 479 480 static const char *ak8975_match_acpi_device(struct device *dev, 481 enum asahi_compass_chipset *chipset) 482 { 483 const struct acpi_device_id *id; 484 485 id = acpi_match_device(dev->driver->acpi_match_table, dev); 486 if (!id) 487 return NULL; 488 *chipset = (int)id->driver_data; 489 490 return dev_name(dev); 491 } 492 493 static int ak8975_probe(struct i2c_client *client, 494 const struct i2c_device_id *id) 495 { 496 struct ak8975_data *data; 497 struct iio_dev *indio_dev; 498 int eoc_gpio; 499 int err; 500 const char *name = NULL; 501 502 /* Grab and set up the supplied GPIO. */ 503 if (client->dev.platform_data) 504 eoc_gpio = *(int *)(client->dev.platform_data); 505 else if (client->dev.of_node) 506 eoc_gpio = of_get_gpio(client->dev.of_node, 0); 507 else 508 eoc_gpio = -1; 509 510 if (eoc_gpio == -EPROBE_DEFER) 511 return -EPROBE_DEFER; 512 513 /* We may not have a GPIO based IRQ to scan, that is fine, we will 514 poll if so */ 515 if (gpio_is_valid(eoc_gpio)) { 516 err = devm_gpio_request_one(&client->dev, eoc_gpio, 517 GPIOF_IN, "ak_8975"); 518 if (err < 0) { 519 dev_err(&client->dev, 520 "failed to request GPIO %d, error %d\n", 521 eoc_gpio, err); 522 return err; 523 } 524 } 525 526 /* Register with IIO */ 527 indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data)); 528 if (indio_dev == NULL) 529 return -ENOMEM; 530 531 data = iio_priv(indio_dev); 532 i2c_set_clientdata(client, indio_dev); 533 534 data->client = client; 535 data->eoc_gpio = eoc_gpio; 536 data->eoc_irq = 0; 537 538 /* id will be NULL when enumerated via ACPI */ 539 if (id) { 540 data->chipset = 541 (enum asahi_compass_chipset)(id->driver_data); 542 name = id->name; 543 } else if (ACPI_HANDLE(&client->dev)) 544 name = ak8975_match_acpi_device(&client->dev, &data->chipset); 545 else 546 return -ENOSYS; 547 548 dev_dbg(&client->dev, "Asahi compass chip %s\n", name); 549 550 /* Perform some basic start-of-day setup of the device. */ 551 err = ak8975_setup(client); 552 if (err < 0) { 553 dev_err(&client->dev, "AK8975 initialization fails\n"); 554 return err; 555 } 556 557 data->client = client; 558 mutex_init(&data->lock); 559 data->eoc_gpio = eoc_gpio; 560 indio_dev->dev.parent = &client->dev; 561 indio_dev->channels = ak8975_channels; 562 indio_dev->num_channels = ARRAY_SIZE(ak8975_channels); 563 indio_dev->info = &ak8975_info; 564 indio_dev->modes = INDIO_DIRECT_MODE; 565 indio_dev->name = name; 566 err = devm_iio_device_register(&client->dev, indio_dev); 567 if (err < 0) 568 return err; 569 570 return 0; 571 } 572 573 static const struct i2c_device_id ak8975_id[] = { 574 {"ak8975", AK8975}, 575 {"ak8963", AK8963}, 576 {} 577 }; 578 579 MODULE_DEVICE_TABLE(i2c, ak8975_id); 580 581 static const struct of_device_id ak8975_of_match[] = { 582 { .compatible = "asahi-kasei,ak8975", }, 583 { .compatible = "ak8975", }, 584 { } 585 }; 586 MODULE_DEVICE_TABLE(of, ak8975_of_match); 587 588 static struct i2c_driver ak8975_driver = { 589 .driver = { 590 .name = "ak8975", 591 .of_match_table = ak8975_of_match, 592 .acpi_match_table = ACPI_PTR(ak_acpi_match), 593 }, 594 .probe = ak8975_probe, 595 .id_table = ak8975_id, 596 }; 597 module_i2c_driver(ak8975_driver); 598 599 MODULE_AUTHOR("Laxman Dewangan <ldewangan@nvidia.com>"); 600 MODULE_DESCRIPTION("AK8975 magnetometer driver"); 601 MODULE_LICENSE("GPL"); 602