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, /* 100 Hz */ 88 MMC35240_16_BITS_FAST, /* 200 Hz */ 89 MMC35240_14_BITS, /* 333 Hz */ 90 MMC35240_12_BITS, /* 666 Hz */ 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, 100Hz ODR */ 104 { 105 {1024, 1024, 1024}, 106 32768, 107 }, 108 /* 16 bits, 200Hz ODR */ 109 { 110 {1024, 1024, 770}, 111 32768, 112 }, 113 /* 14 bits, 333Hz ODR */ 114 { 115 {256, 256, 193}, 116 8192, 117 }, 118 /* 12 bits, 666Hz 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 int mmc35240_samp_freq[] = {100, 200, 333, 666}; 137 138 static IIO_CONST_ATTR_SAMP_FREQ_AVAIL("100 200 333 666"); 139 140 #define MMC35240_CHANNEL(_axis) { \ 141 .type = IIO_MAGN, \ 142 .modified = 1, \ 143 .channel2 = IIO_MOD_ ## _axis, \ 144 .address = AXIS_ ## _axis, \ 145 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \ 146 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SAMP_FREQ) | \ 147 BIT(IIO_CHAN_INFO_SCALE), \ 148 } 149 150 static const struct iio_chan_spec mmc35240_channels[] = { 151 MMC35240_CHANNEL(X), 152 MMC35240_CHANNEL(Y), 153 MMC35240_CHANNEL(Z), 154 }; 155 156 static struct attribute *mmc35240_attributes[] = { 157 &iio_const_attr_sampling_frequency_available.dev_attr.attr, 158 NULL 159 }; 160 161 static const struct attribute_group mmc35240_attribute_group = { 162 .attrs = mmc35240_attributes, 163 }; 164 165 static int mmc35240_get_samp_freq_index(struct mmc35240_data *data, 166 int val, int val2) 167 { 168 int i; 169 170 for (i = 0; i < ARRAY_SIZE(mmc35240_samp_freq); i++) 171 if (mmc35240_samp_freq[i] == val) 172 return i; 173 return -EINVAL; 174 } 175 176 static int mmc35240_hw_set(struct mmc35240_data *data, bool set) 177 { 178 int ret; 179 u8 coil_bit; 180 181 /* 182 * Recharge the capacitor at VCAP pin, requested to be issued 183 * before a SET/RESET command. 184 */ 185 ret = regmap_update_bits(data->regmap, MMC35240_REG_CTRL0, 186 MMC35240_CTRL0_REFILL_BIT, 187 MMC35240_CTRL0_REFILL_BIT); 188 if (ret < 0) 189 return ret; 190 usleep_range(MMC35240_WAIT_CHARGE_PUMP, MMC35240_WAIT_CHARGE_PUMP + 1); 191 192 if (set) 193 coil_bit = MMC35240_CTRL0_SET_BIT; 194 else 195 coil_bit = MMC35240_CTRL0_RESET_BIT; 196 197 return regmap_update_bits(data->regmap, MMC35240_REG_CTRL0, 198 MMC35240_CTRL0_REFILL_BIT, 199 coil_bit); 200 } 201 202 static int mmc35240_init(struct mmc35240_data *data) 203 { 204 int ret, y_convert, z_convert; 205 unsigned int reg_id; 206 u8 otp_data[6]; 207 208 ret = regmap_read(data->regmap, MMC35240_REG_ID, ®_id); 209 if (ret < 0) { 210 dev_err(&data->client->dev, "Error reading product id\n"); 211 return ret; 212 } 213 214 dev_dbg(&data->client->dev, "MMC35240 chip id %x\n", reg_id); 215 216 /* 217 * make sure we restore sensor characteristics, by doing 218 * a RESET/SET sequence 219 */ 220 ret = mmc35240_hw_set(data, false); 221 if (ret < 0) 222 return ret; 223 usleep_range(MMC53240_WAIT_SET_RESET, MMC53240_WAIT_SET_RESET + 1); 224 225 ret = mmc35240_hw_set(data, true); 226 if (ret < 0) 227 return ret; 228 229 /* set default sampling frequency */ 230 ret = regmap_update_bits(data->regmap, MMC35240_REG_CTRL1, 231 MMC35240_CTRL1_BW_MASK, 232 data->res << MMC35240_CTRL1_BW_SHIFT); 233 if (ret < 0) 234 return ret; 235 236 ret = regmap_bulk_read(data->regmap, MMC35240_OTP_START_ADDR, 237 (u8 *)otp_data, sizeof(otp_data)); 238 if (ret < 0) 239 return ret; 240 241 y_convert = MMC35240_OTP_CONVERT_Y(((otp_data[1] & 0x03) << 4) | 242 (otp_data[2] >> 4)); 243 z_convert = MMC35240_OTP_CONVERT_Z(otp_data[3] & 0x3f); 244 245 data->axis_coef[0] = MMC35240_X_COEFF(1); 246 data->axis_coef[1] = MMC35240_Y_COEFF(y_convert); 247 data->axis_coef[2] = MMC35240_Z_COEFF(z_convert); 248 249 data->axis_scale[0] = 1; 250 data->axis_scale[1] = 1000; 251 data->axis_scale[2] = 10000; 252 253 return 0; 254 } 255 256 static int mmc35240_take_measurement(struct mmc35240_data *data) 257 { 258 int ret, tries = 100; 259 unsigned int reg_status; 260 261 ret = regmap_write(data->regmap, MMC35240_REG_CTRL0, 262 MMC35240_CTRL0_TM_BIT); 263 if (ret < 0) 264 return ret; 265 266 while (tries-- > 0) { 267 ret = regmap_read(data->regmap, MMC35240_REG_STATUS, 268 ®_status); 269 if (ret < 0) 270 return ret; 271 if (reg_status & MMC35240_STATUS_MEAS_DONE_BIT) 272 break; 273 /* minimum wait time to complete measurement is 10 ms */ 274 usleep_range(10000, 11000); 275 } 276 277 if (tries < 0) { 278 dev_err(&data->client->dev, "data not ready\n"); 279 return -EIO; 280 } 281 282 return 0; 283 } 284 285 static int mmc35240_read_measurement(struct mmc35240_data *data, __le16 buf[3]) 286 { 287 int ret; 288 289 ret = mmc35240_take_measurement(data); 290 if (ret < 0) 291 return ret; 292 293 return regmap_bulk_read(data->regmap, MMC35240_REG_XOUT_L, (u8 *)buf, 294 3 * sizeof(__le16)); 295 } 296 297 /** 298 * mmc35240_raw_to_mgauss - convert raw readings to milli gauss. Also apply 299 compensation for output value. 300 * 301 * @data: device private data 302 * @index: axis index for which we want the conversion 303 * @buf: raw data to be converted, 2 bytes in little endian format 304 * @val: compensated output reading (unit is milli gauss) 305 * 306 * Returns: 0 in case of success, -EINVAL when @index is not valid 307 */ 308 static int mmc35240_raw_to_mgauss(struct mmc35240_data *data, int index, 309 __le16 buf[], int *val) 310 { 311 int raw_x, raw_y, raw_z; 312 int sens_x, sens_y, sens_z; 313 int nfo; 314 315 raw_x = le16_to_cpu(buf[AXIS_X]); 316 raw_y = le16_to_cpu(buf[AXIS_Y]); 317 raw_z = le16_to_cpu(buf[AXIS_Z]); 318 319 sens_x = mmc35240_props_table[data->res].sens[AXIS_X]; 320 sens_y = mmc35240_props_table[data->res].sens[AXIS_Y]; 321 sens_z = mmc35240_props_table[data->res].sens[AXIS_Z]; 322 323 nfo = mmc35240_props_table[data->res].nfo; 324 325 switch (index) { 326 case AXIS_X: 327 *val = (raw_x - nfo) * 1000 / sens_x; 328 break; 329 case AXIS_Y: 330 *val = (raw_y - nfo) * 1000 / sens_y - 331 (raw_z - nfo) * 1000 / sens_z; 332 break; 333 case AXIS_Z: 334 *val = (raw_y - nfo) * 1000 / sens_y + 335 (raw_z - nfo) * 1000 / sens_z; 336 break; 337 default: 338 return -EINVAL; 339 } 340 /* apply OTP compensation */ 341 *val = (*val) * data->axis_coef[index] / data->axis_scale[index]; 342 343 return 0; 344 } 345 346 static int mmc35240_read_raw(struct iio_dev *indio_dev, 347 struct iio_chan_spec const *chan, int *val, 348 int *val2, long mask) 349 { 350 struct mmc35240_data *data = iio_priv(indio_dev); 351 int ret, i; 352 unsigned int reg; 353 __le16 buf[3]; 354 355 switch (mask) { 356 case IIO_CHAN_INFO_RAW: 357 mutex_lock(&data->mutex); 358 ret = mmc35240_read_measurement(data, buf); 359 mutex_unlock(&data->mutex); 360 if (ret < 0) 361 return ret; 362 ret = mmc35240_raw_to_mgauss(data, chan->address, buf, val); 363 if (ret < 0) 364 return ret; 365 return IIO_VAL_INT; 366 case IIO_CHAN_INFO_SCALE: 367 *val = 0; 368 *val2 = 1000; 369 return IIO_VAL_INT_PLUS_MICRO; 370 case IIO_CHAN_INFO_SAMP_FREQ: 371 mutex_lock(&data->mutex); 372 ret = regmap_read(data->regmap, MMC35240_REG_CTRL1, ®); 373 mutex_unlock(&data->mutex); 374 if (ret < 0) 375 return ret; 376 377 i = (reg & MMC35240_CTRL1_BW_MASK) >> MMC35240_CTRL1_BW_SHIFT; 378 if (i < 0 || i >= ARRAY_SIZE(mmc35240_samp_freq)) 379 return -EINVAL; 380 381 *val = mmc35240_samp_freq[i]; 382 *val2 = 0; 383 return IIO_VAL_INT; 384 default: 385 return -EINVAL; 386 } 387 } 388 389 static int mmc35240_write_raw(struct iio_dev *indio_dev, 390 struct iio_chan_spec const *chan, int val, 391 int val2, long mask) 392 { 393 struct mmc35240_data *data = iio_priv(indio_dev); 394 int i, ret; 395 396 switch (mask) { 397 case IIO_CHAN_INFO_SAMP_FREQ: 398 i = mmc35240_get_samp_freq_index(data, val, val2); 399 if (i < 0) 400 return -EINVAL; 401 mutex_lock(&data->mutex); 402 ret = regmap_update_bits(data->regmap, MMC35240_REG_CTRL1, 403 MMC35240_CTRL1_BW_MASK, 404 i << MMC35240_CTRL1_BW_SHIFT); 405 mutex_unlock(&data->mutex); 406 return ret; 407 default: 408 return -EINVAL; 409 } 410 } 411 412 static const struct iio_info mmc35240_info = { 413 .driver_module = THIS_MODULE, 414 .read_raw = mmc35240_read_raw, 415 .write_raw = mmc35240_write_raw, 416 .attrs = &mmc35240_attribute_group, 417 }; 418 419 static bool mmc35240_is_writeable_reg(struct device *dev, unsigned int reg) 420 { 421 switch (reg) { 422 case MMC35240_REG_CTRL0: 423 case MMC35240_REG_CTRL1: 424 return true; 425 default: 426 return false; 427 } 428 } 429 430 static bool mmc35240_is_readable_reg(struct device *dev, unsigned int reg) 431 { 432 switch (reg) { 433 case MMC35240_REG_XOUT_L: 434 case MMC35240_REG_XOUT_H: 435 case MMC35240_REG_YOUT_L: 436 case MMC35240_REG_YOUT_H: 437 case MMC35240_REG_ZOUT_L: 438 case MMC35240_REG_ZOUT_H: 439 case MMC35240_REG_STATUS: 440 case MMC35240_REG_ID: 441 return true; 442 default: 443 return false; 444 } 445 } 446 447 static bool mmc35240_is_volatile_reg(struct device *dev, unsigned int reg) 448 { 449 switch (reg) { 450 case MMC35240_REG_CTRL0: 451 case MMC35240_REG_CTRL1: 452 return false; 453 default: 454 return true; 455 } 456 } 457 458 static struct reg_default mmc35240_reg_defaults[] = { 459 { MMC35240_REG_CTRL0, 0x00 }, 460 { MMC35240_REG_CTRL1, 0x00 }, 461 }; 462 463 static const struct regmap_config mmc35240_regmap_config = { 464 .name = MMC35240_REGMAP_NAME, 465 466 .reg_bits = 8, 467 .val_bits = 8, 468 469 .max_register = MMC35240_REG_ID, 470 .cache_type = REGCACHE_FLAT, 471 472 .writeable_reg = mmc35240_is_writeable_reg, 473 .readable_reg = mmc35240_is_readable_reg, 474 .volatile_reg = mmc35240_is_volatile_reg, 475 476 .reg_defaults = mmc35240_reg_defaults, 477 .num_reg_defaults = ARRAY_SIZE(mmc35240_reg_defaults), 478 }; 479 480 static int mmc35240_probe(struct i2c_client *client, 481 const struct i2c_device_id *id) 482 { 483 struct mmc35240_data *data; 484 struct iio_dev *indio_dev; 485 struct regmap *regmap; 486 int ret; 487 488 indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data)); 489 if (!indio_dev) 490 return -ENOMEM; 491 492 regmap = devm_regmap_init_i2c(client, &mmc35240_regmap_config); 493 if (IS_ERR(regmap)) { 494 dev_err(&client->dev, "regmap initialization failed\n"); 495 return PTR_ERR(regmap); 496 } 497 498 data = iio_priv(indio_dev); 499 data->client = client; 500 data->regmap = regmap; 501 data->res = MMC35240_16_BITS_SLOW; 502 503 mutex_init(&data->mutex); 504 505 indio_dev->dev.parent = &client->dev; 506 indio_dev->info = &mmc35240_info; 507 indio_dev->name = MMC35240_DRV_NAME; 508 indio_dev->channels = mmc35240_channels; 509 indio_dev->num_channels = ARRAY_SIZE(mmc35240_channels); 510 indio_dev->modes = INDIO_DIRECT_MODE; 511 512 ret = mmc35240_init(data); 513 if (ret < 0) { 514 dev_err(&client->dev, "mmc35240 chip init failed\n"); 515 return ret; 516 } 517 return devm_iio_device_register(&client->dev, indio_dev); 518 } 519 520 #ifdef CONFIG_PM_SLEEP 521 static int mmc35240_suspend(struct device *dev) 522 { 523 struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev)); 524 struct mmc35240_data *data = iio_priv(indio_dev); 525 526 regcache_cache_only(data->regmap, true); 527 528 return 0; 529 } 530 531 static int mmc35240_resume(struct device *dev) 532 { 533 struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev)); 534 struct mmc35240_data *data = iio_priv(indio_dev); 535 int ret; 536 537 regcache_mark_dirty(data->regmap); 538 ret = regcache_sync_region(data->regmap, MMC35240_REG_CTRL0, 539 MMC35240_REG_CTRL1); 540 if (ret < 0) 541 dev_err(dev, "Failed to restore control registers\n"); 542 543 regcache_cache_only(data->regmap, false); 544 545 return 0; 546 } 547 #endif 548 549 static const struct dev_pm_ops mmc35240_pm_ops = { 550 SET_SYSTEM_SLEEP_PM_OPS(mmc35240_suspend, mmc35240_resume) 551 }; 552 553 static const struct acpi_device_id mmc35240_acpi_match[] = { 554 {"MMC35240", 0}, 555 { }, 556 }; 557 MODULE_DEVICE_TABLE(acpi, mmc35240_acpi_match); 558 559 static const struct i2c_device_id mmc35240_id[] = { 560 {"mmc35240", 0}, 561 {} 562 }; 563 MODULE_DEVICE_TABLE(i2c, mmc35240_id); 564 565 static struct i2c_driver mmc35240_driver = { 566 .driver = { 567 .name = MMC35240_DRV_NAME, 568 .pm = &mmc35240_pm_ops, 569 .acpi_match_table = ACPI_PTR(mmc35240_acpi_match), 570 }, 571 .probe = mmc35240_probe, 572 .id_table = mmc35240_id, 573 }; 574 575 module_i2c_driver(mmc35240_driver); 576 577 MODULE_AUTHOR("Daniel Baluta <daniel.baluta@intel.com>"); 578 MODULE_DESCRIPTION("MEMSIC MMC35240 magnetic sensor driver"); 579 MODULE_LICENSE("GPL v2"); 580