1 /* 2 * MMC35240 - MEMSIC 3-axis Magnetic Sensor 3 * 4 * Copyright (c) 2015, Intel Corporation. 5 * 6 * This file is subject to the terms and conditions of version 2 of 7 * the GNU General Public License. See the file COPYING in the main 8 * directory of this archive for more details. 9 * 10 * IIO driver for MMC35240 (7-bit I2C slave address 0x30). 11 * 12 * TODO: offset, ACPI, continuous measurement mode, PM 13 */ 14 15 #include <linux/module.h> 16 #include <linux/init.h> 17 #include <linux/i2c.h> 18 #include <linux/delay.h> 19 #include <linux/regmap.h> 20 #include <linux/acpi.h> 21 #include <linux/pm.h> 22 23 #include <linux/iio/iio.h> 24 #include <linux/iio/sysfs.h> 25 26 #define MMC35240_DRV_NAME "mmc35240" 27 #define MMC35240_REGMAP_NAME "mmc35240_regmap" 28 29 #define MMC35240_REG_XOUT_L 0x00 30 #define MMC35240_REG_XOUT_H 0x01 31 #define MMC35240_REG_YOUT_L 0x02 32 #define MMC35240_REG_YOUT_H 0x03 33 #define MMC35240_REG_ZOUT_L 0x04 34 #define MMC35240_REG_ZOUT_H 0x05 35 36 #define MMC35240_REG_STATUS 0x06 37 #define MMC35240_REG_CTRL0 0x07 38 #define MMC35240_REG_CTRL1 0x08 39 40 #define MMC35240_REG_ID 0x20 41 42 #define MMC35240_STATUS_MEAS_DONE_BIT BIT(0) 43 44 #define MMC35240_CTRL0_REFILL_BIT BIT(7) 45 #define MMC35240_CTRL0_RESET_BIT BIT(6) 46 #define MMC35240_CTRL0_SET_BIT BIT(5) 47 #define MMC35240_CTRL0_CMM_BIT BIT(1) 48 #define MMC35240_CTRL0_TM_BIT BIT(0) 49 50 /* output resolution bits */ 51 #define MMC35240_CTRL1_BW0_BIT BIT(0) 52 #define MMC35240_CTRL1_BW1_BIT BIT(1) 53 54 #define MMC35240_CTRL1_BW_MASK (MMC35240_CTRL1_BW0_BIT | \ 55 MMC35240_CTRL1_BW1_BIT) 56 #define MMC35240_CTRL1_BW_SHIFT 0 57 58 #define MMC35240_WAIT_CHARGE_PUMP 50000 /* us */ 59 #define MMC53240_WAIT_SET_RESET 1000 /* us */ 60 61 /* 62 * Memsic OTP process code piece is put here for reference: 63 * 64 * #define OTP_CONVERT(REG) ((float)((REG) >=32 ? (32 - (REG)) : (REG)) * 0.006 65 * 1) For X axis, the COEFFICIENT is always 1. 66 * 2) For Y axis, the COEFFICIENT is as below: 67 * f_OTP_matrix[4] = OTP_CONVERT(((reg_data[1] & 0x03) << 4) | 68 * (reg_data[2] >> 4)) + 1.0; 69 * 3) For Z axis, the COEFFICIENT is as below: 70 * f_OTP_matrix[8] = (OTP_CONVERT(reg_data[3] & 0x3f) + 1) * 1.35; 71 * We implemented the OTP logic into driver. 72 */ 73 74 /* scale = 1000 here for Y otp */ 75 #define MMC35240_OTP_CONVERT_Y(REG) (((REG) >= 32 ? (32 - (REG)) : (REG)) * 6) 76 77 /* 0.6 * 1.35 = 0.81, scale 10000 for Z otp */ 78 #define MMC35240_OTP_CONVERT_Z(REG) (((REG) >= 32 ? (32 - (REG)) : (REG)) * 81) 79 80 #define MMC35240_X_COEFF(x) (x) 81 #define MMC35240_Y_COEFF(y) (y + 1000) 82 #define MMC35240_Z_COEFF(z) (z + 13500) 83 84 #define MMC35240_OTP_START_ADDR 0x1B 85 86 enum mmc35240_resolution { 87 MMC35240_16_BITS_SLOW = 0, /* 7.92 ms */ 88 MMC35240_16_BITS_FAST, /* 4.08 ms */ 89 MMC35240_14_BITS, /* 2.16 ms */ 90 MMC35240_12_BITS, /* 1.20 ms */ 91 }; 92 93 enum mmc35240_axis { 94 AXIS_X = 0, 95 AXIS_Y, 96 AXIS_Z, 97 }; 98 99 static const struct { 100 int sens[3]; /* sensitivity per X, Y, Z axis */ 101 int nfo; /* null field output */ 102 } mmc35240_props_table[] = { 103 /* 16 bits, 125Hz ODR */ 104 { 105 {1024, 1024, 1024}, 106 32768, 107 }, 108 /* 16 bits, 250Hz ODR */ 109 { 110 {1024, 1024, 770}, 111 32768, 112 }, 113 /* 14 bits, 450Hz ODR */ 114 { 115 {256, 256, 193}, 116 8192, 117 }, 118 /* 12 bits, 800Hz ODR */ 119 { 120 {64, 64, 48}, 121 2048, 122 }, 123 }; 124 125 struct mmc35240_data { 126 struct i2c_client *client; 127 struct mutex mutex; 128 struct regmap *regmap; 129 enum mmc35240_resolution res; 130 131 /* OTP compensation */ 132 int axis_coef[3]; 133 int axis_scale[3]; 134 }; 135 136 static const struct { 137 int val; 138 int val2; 139 } mmc35240_samp_freq[] = { {1, 500000}, 140 {13, 0}, 141 {25, 0}, 142 {50, 0} }; 143 144 static IIO_CONST_ATTR_SAMP_FREQ_AVAIL("1.5 13 25 50"); 145 146 #define MMC35240_CHANNEL(_axis) { \ 147 .type = IIO_MAGN, \ 148 .modified = 1, \ 149 .channel2 = IIO_MOD_ ## _axis, \ 150 .address = AXIS_ ## _axis, \ 151 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \ 152 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SAMP_FREQ) | \ 153 BIT(IIO_CHAN_INFO_SCALE), \ 154 } 155 156 static const struct iio_chan_spec mmc35240_channels[] = { 157 MMC35240_CHANNEL(X), 158 MMC35240_CHANNEL(Y), 159 MMC35240_CHANNEL(Z), 160 }; 161 162 static struct attribute *mmc35240_attributes[] = { 163 &iio_const_attr_sampling_frequency_available.dev_attr.attr, 164 NULL 165 }; 166 167 static const struct attribute_group mmc35240_attribute_group = { 168 .attrs = mmc35240_attributes, 169 }; 170 171 static int mmc35240_get_samp_freq_index(struct mmc35240_data *data, 172 int val, int val2) 173 { 174 int i; 175 176 for (i = 0; i < ARRAY_SIZE(mmc35240_samp_freq); i++) 177 if (mmc35240_samp_freq[i].val == val && 178 mmc35240_samp_freq[i].val2 == val2) 179 return i; 180 return -EINVAL; 181 } 182 183 static int mmc35240_hw_set(struct mmc35240_data *data, bool set) 184 { 185 int ret; 186 u8 coil_bit; 187 188 /* 189 * Recharge the capacitor at VCAP pin, requested to be issued 190 * before a SET/RESET command. 191 */ 192 ret = regmap_update_bits(data->regmap, MMC35240_REG_CTRL0, 193 MMC35240_CTRL0_REFILL_BIT, 194 MMC35240_CTRL0_REFILL_BIT); 195 if (ret < 0) 196 return ret; 197 usleep_range(MMC35240_WAIT_CHARGE_PUMP, MMC35240_WAIT_CHARGE_PUMP + 1); 198 199 if (set) 200 coil_bit = MMC35240_CTRL0_SET_BIT; 201 else 202 coil_bit = MMC35240_CTRL0_RESET_BIT; 203 204 return regmap_update_bits(data->regmap, MMC35240_REG_CTRL0, 205 coil_bit, coil_bit); 206 207 } 208 209 static int mmc35240_init(struct mmc35240_data *data) 210 { 211 int ret, y_convert, z_convert; 212 unsigned int reg_id; 213 u8 otp_data[6]; 214 215 ret = regmap_read(data->regmap, MMC35240_REG_ID, ®_id); 216 if (ret < 0) { 217 dev_err(&data->client->dev, "Error reading product id\n"); 218 return ret; 219 } 220 221 dev_dbg(&data->client->dev, "MMC35240 chip id %x\n", reg_id); 222 223 /* 224 * make sure we restore sensor characteristics, by doing 225 * a SET/RESET sequence, the axis polarity being naturally 226 * aligned after RESET 227 */ 228 ret = mmc35240_hw_set(data, true); 229 if (ret < 0) 230 return ret; 231 usleep_range(MMC53240_WAIT_SET_RESET, MMC53240_WAIT_SET_RESET + 1); 232 233 ret = mmc35240_hw_set(data, false); 234 if (ret < 0) 235 return ret; 236 237 /* set default sampling frequency */ 238 ret = regmap_update_bits(data->regmap, MMC35240_REG_CTRL1, 239 MMC35240_CTRL1_BW_MASK, 240 data->res << MMC35240_CTRL1_BW_SHIFT); 241 if (ret < 0) 242 return ret; 243 244 ret = regmap_bulk_read(data->regmap, MMC35240_OTP_START_ADDR, 245 (u8 *)otp_data, sizeof(otp_data)); 246 if (ret < 0) 247 return ret; 248 249 y_convert = MMC35240_OTP_CONVERT_Y(((otp_data[1] & 0x03) << 4) | 250 (otp_data[2] >> 4)); 251 z_convert = MMC35240_OTP_CONVERT_Z(otp_data[3] & 0x3f); 252 253 data->axis_coef[0] = MMC35240_X_COEFF(1); 254 data->axis_coef[1] = MMC35240_Y_COEFF(y_convert); 255 data->axis_coef[2] = MMC35240_Z_COEFF(z_convert); 256 257 data->axis_scale[0] = 1; 258 data->axis_scale[1] = 1000; 259 data->axis_scale[2] = 10000; 260 261 return 0; 262 } 263 264 static int mmc35240_take_measurement(struct mmc35240_data *data) 265 { 266 int ret, tries = 100; 267 unsigned int reg_status; 268 269 ret = regmap_write(data->regmap, MMC35240_REG_CTRL0, 270 MMC35240_CTRL0_TM_BIT); 271 if (ret < 0) 272 return ret; 273 274 while (tries-- > 0) { 275 ret = regmap_read(data->regmap, MMC35240_REG_STATUS, 276 ®_status); 277 if (ret < 0) 278 return ret; 279 if (reg_status & MMC35240_STATUS_MEAS_DONE_BIT) 280 break; 281 /* minimum wait time to complete measurement is 10 ms */ 282 usleep_range(10000, 11000); 283 } 284 285 if (tries < 0) { 286 dev_err(&data->client->dev, "data not ready\n"); 287 return -EIO; 288 } 289 290 return 0; 291 } 292 293 static int mmc35240_read_measurement(struct mmc35240_data *data, __le16 buf[3]) 294 { 295 int ret; 296 297 ret = mmc35240_take_measurement(data); 298 if (ret < 0) 299 return ret; 300 301 return regmap_bulk_read(data->regmap, MMC35240_REG_XOUT_L, (u8 *)buf, 302 3 * sizeof(__le16)); 303 } 304 305 /** 306 * mmc35240_raw_to_mgauss - convert raw readings to milli gauss. Also apply 307 compensation for output value. 308 * 309 * @data: device private data 310 * @index: axis index for which we want the conversion 311 * @buf: raw data to be converted, 2 bytes in little endian format 312 * @val: compensated output reading (unit is milli gauss) 313 * 314 * Returns: 0 in case of success, -EINVAL when @index is not valid 315 */ 316 static int mmc35240_raw_to_mgauss(struct mmc35240_data *data, int index, 317 __le16 buf[], int *val) 318 { 319 int raw[3]; 320 int sens[3]; 321 int nfo; 322 323 raw[AXIS_X] = le16_to_cpu(buf[AXIS_X]); 324 raw[AXIS_Y] = le16_to_cpu(buf[AXIS_Y]); 325 raw[AXIS_Z] = le16_to_cpu(buf[AXIS_Z]); 326 327 sens[AXIS_X] = mmc35240_props_table[data->res].sens[AXIS_X]; 328 sens[AXIS_Y] = mmc35240_props_table[data->res].sens[AXIS_Y]; 329 sens[AXIS_Z] = mmc35240_props_table[data->res].sens[AXIS_Z]; 330 331 nfo = mmc35240_props_table[data->res].nfo; 332 333 switch (index) { 334 case AXIS_X: 335 *val = (raw[AXIS_X] - nfo) * 1000 / sens[AXIS_X]; 336 break; 337 case AXIS_Y: 338 *val = (raw[AXIS_Y] - nfo) * 1000 / sens[AXIS_Y] - 339 (raw[AXIS_Z] - nfo) * 1000 / sens[AXIS_Z]; 340 break; 341 case AXIS_Z: 342 *val = (raw[AXIS_Y] - nfo) * 1000 / sens[AXIS_Y] + 343 (raw[AXIS_Z] - nfo) * 1000 / sens[AXIS_Z]; 344 break; 345 default: 346 return -EINVAL; 347 } 348 /* apply OTP compensation */ 349 *val = (*val) * data->axis_coef[index] / data->axis_scale[index]; 350 351 return 0; 352 } 353 354 static int mmc35240_read_raw(struct iio_dev *indio_dev, 355 struct iio_chan_spec const *chan, int *val, 356 int *val2, long mask) 357 { 358 struct mmc35240_data *data = iio_priv(indio_dev); 359 int ret, i; 360 unsigned int reg; 361 __le16 buf[3]; 362 363 switch (mask) { 364 case IIO_CHAN_INFO_RAW: 365 mutex_lock(&data->mutex); 366 ret = mmc35240_read_measurement(data, buf); 367 mutex_unlock(&data->mutex); 368 if (ret < 0) 369 return ret; 370 ret = mmc35240_raw_to_mgauss(data, chan->address, buf, val); 371 if (ret < 0) 372 return ret; 373 return IIO_VAL_INT; 374 case IIO_CHAN_INFO_SCALE: 375 *val = 0; 376 *val2 = 1000; 377 return IIO_VAL_INT_PLUS_MICRO; 378 case IIO_CHAN_INFO_SAMP_FREQ: 379 mutex_lock(&data->mutex); 380 ret = regmap_read(data->regmap, MMC35240_REG_CTRL1, ®); 381 mutex_unlock(&data->mutex); 382 if (ret < 0) 383 return ret; 384 385 i = (reg & MMC35240_CTRL1_BW_MASK) >> MMC35240_CTRL1_BW_SHIFT; 386 if (i < 0 || i >= ARRAY_SIZE(mmc35240_samp_freq)) 387 return -EINVAL; 388 389 *val = mmc35240_samp_freq[i].val; 390 *val2 = mmc35240_samp_freq[i].val2; 391 return IIO_VAL_INT_PLUS_MICRO; 392 default: 393 return -EINVAL; 394 } 395 } 396 397 static int mmc35240_write_raw(struct iio_dev *indio_dev, 398 struct iio_chan_spec const *chan, int val, 399 int val2, long mask) 400 { 401 struct mmc35240_data *data = iio_priv(indio_dev); 402 int i, ret; 403 404 switch (mask) { 405 case IIO_CHAN_INFO_SAMP_FREQ: 406 i = mmc35240_get_samp_freq_index(data, val, val2); 407 if (i < 0) 408 return -EINVAL; 409 mutex_lock(&data->mutex); 410 ret = regmap_update_bits(data->regmap, MMC35240_REG_CTRL1, 411 MMC35240_CTRL1_BW_MASK, 412 i << MMC35240_CTRL1_BW_SHIFT); 413 mutex_unlock(&data->mutex); 414 return ret; 415 default: 416 return -EINVAL; 417 } 418 } 419 420 static const struct iio_info mmc35240_info = { 421 .read_raw = mmc35240_read_raw, 422 .write_raw = mmc35240_write_raw, 423 .attrs = &mmc35240_attribute_group, 424 }; 425 426 static bool mmc35240_is_writeable_reg(struct device *dev, unsigned int reg) 427 { 428 switch (reg) { 429 case MMC35240_REG_CTRL0: 430 case MMC35240_REG_CTRL1: 431 return true; 432 default: 433 return false; 434 } 435 } 436 437 static bool mmc35240_is_readable_reg(struct device *dev, unsigned int reg) 438 { 439 switch (reg) { 440 case MMC35240_REG_XOUT_L: 441 case MMC35240_REG_XOUT_H: 442 case MMC35240_REG_YOUT_L: 443 case MMC35240_REG_YOUT_H: 444 case MMC35240_REG_ZOUT_L: 445 case MMC35240_REG_ZOUT_H: 446 case MMC35240_REG_STATUS: 447 case MMC35240_REG_ID: 448 return true; 449 default: 450 return false; 451 } 452 } 453 454 static bool mmc35240_is_volatile_reg(struct device *dev, unsigned int reg) 455 { 456 switch (reg) { 457 case MMC35240_REG_CTRL0: 458 case MMC35240_REG_CTRL1: 459 return false; 460 default: 461 return true; 462 } 463 } 464 465 static struct reg_default mmc35240_reg_defaults[] = { 466 { MMC35240_REG_CTRL0, 0x00 }, 467 { MMC35240_REG_CTRL1, 0x00 }, 468 }; 469 470 static const struct regmap_config mmc35240_regmap_config = { 471 .name = MMC35240_REGMAP_NAME, 472 473 .reg_bits = 8, 474 .val_bits = 8, 475 476 .max_register = MMC35240_REG_ID, 477 .cache_type = REGCACHE_FLAT, 478 479 .writeable_reg = mmc35240_is_writeable_reg, 480 .readable_reg = mmc35240_is_readable_reg, 481 .volatile_reg = mmc35240_is_volatile_reg, 482 483 .reg_defaults = mmc35240_reg_defaults, 484 .num_reg_defaults = ARRAY_SIZE(mmc35240_reg_defaults), 485 }; 486 487 static int mmc35240_probe(struct i2c_client *client, 488 const struct i2c_device_id *id) 489 { 490 struct mmc35240_data *data; 491 struct iio_dev *indio_dev; 492 struct regmap *regmap; 493 int ret; 494 495 indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data)); 496 if (!indio_dev) 497 return -ENOMEM; 498 499 regmap = devm_regmap_init_i2c(client, &mmc35240_regmap_config); 500 if (IS_ERR(regmap)) { 501 dev_err(&client->dev, "regmap initialization failed\n"); 502 return PTR_ERR(regmap); 503 } 504 505 data = iio_priv(indio_dev); 506 i2c_set_clientdata(client, indio_dev); 507 data->client = client; 508 data->regmap = regmap; 509 data->res = MMC35240_16_BITS_SLOW; 510 511 mutex_init(&data->mutex); 512 513 indio_dev->dev.parent = &client->dev; 514 indio_dev->info = &mmc35240_info; 515 indio_dev->name = MMC35240_DRV_NAME; 516 indio_dev->channels = mmc35240_channels; 517 indio_dev->num_channels = ARRAY_SIZE(mmc35240_channels); 518 indio_dev->modes = INDIO_DIRECT_MODE; 519 520 ret = mmc35240_init(data); 521 if (ret < 0) { 522 dev_err(&client->dev, "mmc35240 chip init failed\n"); 523 return ret; 524 } 525 return devm_iio_device_register(&client->dev, indio_dev); 526 } 527 528 #ifdef CONFIG_PM_SLEEP 529 static int mmc35240_suspend(struct device *dev) 530 { 531 struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev)); 532 struct mmc35240_data *data = iio_priv(indio_dev); 533 534 regcache_cache_only(data->regmap, true); 535 536 return 0; 537 } 538 539 static int mmc35240_resume(struct device *dev) 540 { 541 struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev)); 542 struct mmc35240_data *data = iio_priv(indio_dev); 543 int ret; 544 545 regcache_mark_dirty(data->regmap); 546 ret = regcache_sync_region(data->regmap, MMC35240_REG_CTRL0, 547 MMC35240_REG_CTRL1); 548 if (ret < 0) 549 dev_err(dev, "Failed to restore control registers\n"); 550 551 regcache_cache_only(data->regmap, false); 552 553 return 0; 554 } 555 #endif 556 557 static const struct dev_pm_ops mmc35240_pm_ops = { 558 SET_SYSTEM_SLEEP_PM_OPS(mmc35240_suspend, mmc35240_resume) 559 }; 560 561 static const struct of_device_id mmc35240_of_match[] = { 562 { .compatible = "memsic,mmc35240", }, 563 { } 564 }; 565 MODULE_DEVICE_TABLE(of, mmc35240_of_match); 566 567 static const struct acpi_device_id mmc35240_acpi_match[] = { 568 {"MMC35240", 0}, 569 { }, 570 }; 571 MODULE_DEVICE_TABLE(acpi, mmc35240_acpi_match); 572 573 static const struct i2c_device_id mmc35240_id[] = { 574 {"mmc35240", 0}, 575 {} 576 }; 577 MODULE_DEVICE_TABLE(i2c, mmc35240_id); 578 579 static struct i2c_driver mmc35240_driver = { 580 .driver = { 581 .name = MMC35240_DRV_NAME, 582 .of_match_table = mmc35240_of_match, 583 .pm = &mmc35240_pm_ops, 584 .acpi_match_table = ACPI_PTR(mmc35240_acpi_match), 585 }, 586 .probe = mmc35240_probe, 587 .id_table = mmc35240_id, 588 }; 589 590 module_i2c_driver(mmc35240_driver); 591 592 MODULE_AUTHOR("Daniel Baluta <daniel.baluta@intel.com>"); 593 MODULE_DESCRIPTION("MEMSIC MMC35240 magnetic sensor driver"); 594 MODULE_LICENSE("GPL v2"); 595