ak8974.c

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * Driver for the Asahi Kasei EMD Corporation AK8974
   4 * and Aichi Steel AMI305 magnetometer chips.
   5 * Based on a patch from Samu Onkalo and the AK8975 IIO driver.
   6 *
   7 * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).
   8 * Copyright (c) 2010 NVIDIA Corporation.
   9 * Copyright (C) 2016 Linaro Ltd.
  10 *
  11 * Author: Samu Onkalo <samu.p.onkalo@nokia.com>
  12 * Author: Linus Walleij <linus.walleij@linaro.org>
  13 */
  14#include <linux/module.h>
  15#include <linux/mod_devicetable.h>
  16#include <linux/kernel.h>
  17#include <linux/i2c.h>
  18#include <linux/interrupt.h>
  19#include <linux/irq.h> /* For irq_get_irq_data() */
  20#include <linux/completion.h>
  21#include <linux/err.h>
  22#include <linux/mutex.h>
  23#include <linux/delay.h>
  24#include <linux/bitops.h>
  25#include <linux/random.h>
  26#include <linux/regmap.h>
  27#include <linux/regulator/consumer.h>
  28#include <linux/pm_runtime.h>
  29
  30#include <linux/iio/iio.h>
  31#include <linux/iio/sysfs.h>
  32#include <linux/iio/buffer.h>
  33#include <linux/iio/trigger.h>
  34#include <linux/iio/trigger_consumer.h>
  35#include <linux/iio/triggered_buffer.h>
  36
  37/*
  38 * 16-bit registers are little-endian. LSB is at the address defined below
  39 * and MSB is at the next higher address.
  40 */
  41
  42/* These registers are common for AK8974 and AMI30x */
  43#define AK8974_SELFTEST		0x0C
  44#define AK8974_SELFTEST_IDLE	0x55
  45#define AK8974_SELFTEST_OK	0xAA
  46
  47#define AK8974_INFO		0x0D
  48
  49#define AK8974_WHOAMI		0x0F
  50#define AK8974_WHOAMI_VALUE_AMI306 0x46
  51#define AK8974_WHOAMI_VALUE_AMI305 0x47
  52#define AK8974_WHOAMI_VALUE_AK8974 0x48
  53#define AK8974_WHOAMI_VALUE_HSCDTD008A 0x49
  54
  55#define AK8974_DATA_X		0x10
  56#define AK8974_DATA_Y		0x12
  57#define AK8974_DATA_Z		0x14
  58#define AK8974_INT_SRC		0x16
  59#define AK8974_STATUS		0x18
  60#define AK8974_INT_CLEAR	0x1A
  61#define AK8974_CTRL1		0x1B
  62#define AK8974_CTRL2		0x1C
  63#define AK8974_CTRL3		0x1D
  64#define AK8974_INT_CTRL		0x1E
  65#define AK8974_INT_THRES	0x26  /* Absolute any axis value threshold */
  66#define AK8974_PRESET		0x30
  67
  68/* AK8974-specific offsets */
  69#define AK8974_OFFSET_X		0x20
  70#define AK8974_OFFSET_Y		0x22
  71#define AK8974_OFFSET_Z		0x24
  72/* AMI305-specific offsets */
  73#define AMI305_OFFSET_X		0x6C
  74#define AMI305_OFFSET_Y		0x72
  75#define AMI305_OFFSET_Z		0x78
  76
  77/* Different temperature registers */
  78#define AK8974_TEMP		0x31
  79#define AMI305_TEMP		0x60
  80
  81/* AMI306-specific control register */
  82#define AMI306_CTRL4		0x5C
  83
  84/* AMI306 factory calibration data */
  85
  86/* fine axis sensitivity */
  87#define AMI306_FINEOUTPUT_X	0x90
  88#define AMI306_FINEOUTPUT_Y	0x92
  89#define AMI306_FINEOUTPUT_Z	0x94
  90
  91/* axis sensitivity */
  92#define AMI306_SENS_X		0x96
  93#define AMI306_SENS_Y		0x98
  94#define AMI306_SENS_Z		0x9A
  95
  96/* axis cross-interference */
  97#define AMI306_GAIN_PARA_XZ	0x9C
  98#define AMI306_GAIN_PARA_XY	0x9D
  99#define AMI306_GAIN_PARA_YZ	0x9E
 100#define AMI306_GAIN_PARA_YX	0x9F
 101#define AMI306_GAIN_PARA_ZY	0xA0
 102#define AMI306_GAIN_PARA_ZX	0xA1
 103
 104/* offset at ZERO magnetic field */
 105#define AMI306_OFFZERO_X	0xF8
 106#define AMI306_OFFZERO_Y	0xFA
 107#define AMI306_OFFZERO_Z	0xFC
 108
 109
 110#define AK8974_INT_X_HIGH	BIT(7) /* Axis over +threshold  */
 111#define AK8974_INT_Y_HIGH	BIT(6)
 112#define AK8974_INT_Z_HIGH	BIT(5)
 113#define AK8974_INT_X_LOW	BIT(4) /* Axis below -threshold	*/
 114#define AK8974_INT_Y_LOW	BIT(3)
 115#define AK8974_INT_Z_LOW	BIT(2)
 116#define AK8974_INT_RANGE	BIT(1) /* Range overflow (any axis) */
 117
 118#define AK8974_STATUS_DRDY	BIT(6) /* Data ready */
 119#define AK8974_STATUS_OVERRUN	BIT(5) /* Data overrun */
 120#define AK8974_STATUS_INT	BIT(4) /* Interrupt occurred */
 121
 122#define AK8974_CTRL1_POWER	BIT(7) /* 0 = standby; 1 = active */
 123#define AK8974_CTRL1_RATE	BIT(4) /* 0 = 10 Hz; 1 = 20 Hz	 */
 124#define AK8974_CTRL1_FORCE_EN	BIT(1) /* 0 = normal; 1 = force	 */
 125#define AK8974_CTRL1_MODE2	BIT(0) /* 0 */
 126
 127#define AK8974_CTRL2_INT_EN	BIT(4)  /* 1 = enable interrupts	      */
 128#define AK8974_CTRL2_DRDY_EN	BIT(3)  /* 1 = enable data ready signal */
 129#define AK8974_CTRL2_DRDY_POL	BIT(2)  /* 1 = data ready active high   */
 130#define AK8974_CTRL2_RESDEF	(AK8974_CTRL2_DRDY_POL)
 131
 132#define AK8974_CTRL3_RESET	BIT(7) /* Software reset		  */
 133#define AK8974_CTRL3_FORCE	BIT(6) /* Start forced measurement */
 134#define AK8974_CTRL3_SELFTEST	BIT(4) /* Set selftest register	  */
 135#define AK8974_CTRL3_RESDEF	0x00
 136
 137#define AK8974_INT_CTRL_XEN	BIT(7) /* Enable interrupt for this axis */
 138#define AK8974_INT_CTRL_YEN	BIT(6)
 139#define AK8974_INT_CTRL_ZEN	BIT(5)
 140#define AK8974_INT_CTRL_XYZEN	(BIT(7)|BIT(6)|BIT(5))
 141#define AK8974_INT_CTRL_POL	BIT(3) /* 0 = active low; 1 = active high */
 142#define AK8974_INT_CTRL_PULSE	BIT(1) /* 0 = latched; 1 = pulse (50 usec) */
 143#define AK8974_INT_CTRL_RESDEF	(AK8974_INT_CTRL_XYZEN | AK8974_INT_CTRL_POL)
 144
 145/* HSCDTD008A-specific control register */
 146#define HSCDTD008A_CTRL4	0x1E
 147#define HSCDTD008A_CTRL4_MMD	BIT(7)	/* must be set to 1 */
 148#define HSCDTD008A_CTRL4_RANGE	BIT(4)	/* 0 = 14-bit output; 1 = 15-bit output */
 149#define HSCDTD008A_CTRL4_RESDEF	(HSCDTD008A_CTRL4_MMD | HSCDTD008A_CTRL4_RANGE)
 150
 151/* The AMI305 has elaborate FW version and serial number registers */
 152#define AMI305_VER		0xE8
 153#define AMI305_SN		0xEA
 154
 155#define AK8974_MAX_RANGE	2048
 156
 157#define AK8974_POWERON_DELAY	50
 158#define AK8974_ACTIVATE_DELAY	1
 159#define AK8974_SELFTEST_DELAY	1
 160/*
 161 * Set the autosuspend to two orders of magnitude larger than the poweron
 162 * delay to make sane reasonable power tradeoff savings (5 seconds in
 163 * this case).
 164 */
 165#define AK8974_AUTOSUSPEND_DELAY 5000
 166
 167#define AK8974_MEASTIME		3
 168
 169#define AK8974_PWR_ON		1
 170#define AK8974_PWR_OFF		0
 171
 172/**
 173 * struct ak8974 - state container for the AK8974 driver
 174 * @i2c: parent I2C client
 175 * @orientation: mounting matrix, flipped axis etc
 176 * @map: regmap to access the AK8974 registers over I2C
 177 * @regs: the avdd and dvdd power regulators
 178 * @name: the name of the part
 179 * @variant: the whoami ID value (for selecting code paths)
 180 * @lock: locks the magnetometer for exclusive use during a measurement
 181 * @drdy_irq: uses the DRDY IRQ line
 182 * @drdy_complete: completion for DRDY
 183 * @drdy_active_low: the DRDY IRQ is active low
 184 * @scan: timestamps
 185 */
 186struct ak8974 {
 187	struct i2c_client *i2c;
 188	struct iio_mount_matrix orientation;
 189	struct regmap *map;
 190	struct regulator_bulk_data regs[2];
 191	const char *name;
 192	u8 variant;
 193	struct mutex lock;
 194	bool drdy_irq;
 195	struct completion drdy_complete;
 196	bool drdy_active_low;
 197	/* Ensure timestamp is naturally aligned */
 198	struct {
 199		__le16 channels[3];
 200		aligned_s64 ts;
 201	} scan;
 202};
 203
 204static const char ak8974_reg_avdd[] = "avdd";
 205static const char ak8974_reg_dvdd[] = "dvdd";
 206
 207static int ak8974_get_u16_val(struct ak8974 *ak8974, u8 reg, u16 *val)
 208{
 209	int ret;
 210	__le16 bulk;
 211
 212	ret = regmap_bulk_read(ak8974->map, reg, &bulk, 2);
 213	if (ret)
 214		return ret;
 215	*val = le16_to_cpu(bulk);
 216
 217	return 0;
 218}
 219
 220static int ak8974_set_u16_val(struct ak8974 *ak8974, u8 reg, u16 val)
 221{
 222	__le16 bulk = cpu_to_le16(val);
 223
 224	return regmap_bulk_write(ak8974->map, reg, &bulk, 2);
 225}
 226
 227static int ak8974_set_power(struct ak8974 *ak8974, bool mode)
 228{
 229	int ret;
 230	u8 val;
 231
 232	val = mode ? AK8974_CTRL1_POWER : 0;
 233	val |= AK8974_CTRL1_FORCE_EN;
 234	ret = regmap_write(ak8974->map, AK8974_CTRL1, val);
 235	if (ret < 0)
 236		return ret;
 237
 238	if (mode)
 239		msleep(AK8974_ACTIVATE_DELAY);
 240
 241	return 0;
 242}
 243
 244static int ak8974_reset(struct ak8974 *ak8974)
 245{
 246	int ret;
 247
 248	/* Power on to get register access. Sets CTRL1 reg to reset state */
 249	ret = ak8974_set_power(ak8974, AK8974_PWR_ON);
 250	if (ret)
 251		return ret;
 252	ret = regmap_write(ak8974->map, AK8974_CTRL2, AK8974_CTRL2_RESDEF);
 253	if (ret)
 254		return ret;
 255	ret = regmap_write(ak8974->map, AK8974_CTRL3, AK8974_CTRL3_RESDEF);
 256	if (ret)
 257		return ret;
 258	if (ak8974->variant != AK8974_WHOAMI_VALUE_HSCDTD008A) {
 259		ret = regmap_write(ak8974->map, AK8974_INT_CTRL,
 260				   AK8974_INT_CTRL_RESDEF);
 261		if (ret)
 262			return ret;
 263	} else {
 264		ret = regmap_write(ak8974->map, HSCDTD008A_CTRL4,
 265				   HSCDTD008A_CTRL4_RESDEF);
 266		if (ret)
 267			return ret;
 268	}
 269
 270	/* After reset, power off is default state */
 271	return ak8974_set_power(ak8974, AK8974_PWR_OFF);
 272}
 273
 274static int ak8974_configure(struct ak8974 *ak8974)
 275{
 276	int ret;
 277
 278	ret = regmap_write(ak8974->map, AK8974_CTRL2, AK8974_CTRL2_DRDY_EN |
 279			   AK8974_CTRL2_INT_EN);
 280	if (ret)
 281		return ret;
 282	ret = regmap_write(ak8974->map, AK8974_CTRL3, 0);
 283	if (ret)
 284		return ret;
 285	if (ak8974->variant == AK8974_WHOAMI_VALUE_AMI306) {
 286		/* magic from datasheet: set high-speed measurement mode */
 287		ret = ak8974_set_u16_val(ak8974, AMI306_CTRL4, 0xA07E);
 288		if (ret)
 289			return ret;
 290	}
 291	if (ak8974->variant == AK8974_WHOAMI_VALUE_HSCDTD008A)
 292		return 0;
 293	ret = regmap_write(ak8974->map, AK8974_INT_CTRL, AK8974_INT_CTRL_POL);
 294	if (ret)
 295		return ret;
 296
 297	return regmap_write(ak8974->map, AK8974_PRESET, 0);
 298}
 299
 300static int ak8974_trigmeas(struct ak8974 *ak8974)
 301{
 302	unsigned int clear;
 303	u8 mask;
 304	u8 val;
 305	int ret;
 306
 307	/* Clear any previous measurement overflow status */
 308	ret = regmap_read(ak8974->map, AK8974_INT_CLEAR, &clear);
 309	if (ret)
 310		return ret;
 311
 312	/* If we have a DRDY IRQ line, use it */
 313	if (ak8974->drdy_irq) {
 314		mask = AK8974_CTRL2_INT_EN |
 315			AK8974_CTRL2_DRDY_EN |
 316			AK8974_CTRL2_DRDY_POL;
 317		val = AK8974_CTRL2_DRDY_EN;
 318
 319		if (!ak8974->drdy_active_low)
 320			val |= AK8974_CTRL2_DRDY_POL;
 321
 322		init_completion(&ak8974->drdy_complete);
 323		ret = regmap_update_bits(ak8974->map, AK8974_CTRL2,
 324					 mask, val);
 325		if (ret)
 326			return ret;
 327	}
 328
 329	/* Force a measurement */
 330	return regmap_set_bits(ak8974->map, AK8974_CTRL3, AK8974_CTRL3_FORCE);
 331}
 332
 333static int ak8974_await_drdy(struct ak8974 *ak8974)
 334{
 335	int timeout = 2;
 336	unsigned int val;
 337	int ret;
 338
 339	if (ak8974->drdy_irq) {
 340		ret = wait_for_completion_timeout(&ak8974->drdy_complete,
 341					1 + msecs_to_jiffies(1000));
 342		if (!ret) {
 343			dev_err(&ak8974->i2c->dev,
 344				"timeout waiting for DRDY IRQ\n");
 345			return -ETIMEDOUT;
 346		}
 347		return 0;
 348	}
 349
 350	/* Default delay-based poll loop */
 351	do {
 352		msleep(AK8974_MEASTIME);
 353		ret = regmap_read(ak8974->map, AK8974_STATUS, &val);
 354		if (ret < 0)
 355			return ret;
 356		if (val & AK8974_STATUS_DRDY)
 357			return 0;
 358	} while (--timeout);
 359
 360	dev_err(&ak8974->i2c->dev, "timeout waiting for DRDY\n");
 361	return -ETIMEDOUT;
 362}
 363
 364static int ak8974_getresult(struct ak8974 *ak8974, __le16 *result)
 365{
 366	unsigned int src;
 367	int ret;
 368
 369	ret = ak8974_await_drdy(ak8974);
 370	if (ret)
 371		return ret;
 372	ret = regmap_read(ak8974->map, AK8974_INT_SRC, &src);
 373	if (ret < 0)
 374		return ret;
 375
 376	/* Out of range overflow! Strong magnet close? */
 377	if (src & AK8974_INT_RANGE) {
 378		dev_err(&ak8974->i2c->dev,
 379			"range overflow in sensor\n");
 380		return -ERANGE;
 381	}
 382
 383	ret = regmap_bulk_read(ak8974->map, AK8974_DATA_X, result, 6);
 384	if (ret)
 385		return ret;
 386
 387	return ret;
 388}
 389
 390static irqreturn_t ak8974_drdy_irq(int irq, void *d)
 391{
 392	struct ak8974 *ak8974 = d;
 393
 394	if (!ak8974->drdy_irq)
 395		return IRQ_NONE;
 396
 397	/* TODO: timestamp here to get good measurement stamps */
 398	return IRQ_WAKE_THREAD;
 399}
 400
 401static irqreturn_t ak8974_drdy_irq_thread(int irq, void *d)
 402{
 403	struct ak8974 *ak8974 = d;
 404	unsigned int val;
 405	int ret;
 406
 407	/* Check if this was a DRDY from us */
 408	ret = regmap_read(ak8974->map, AK8974_STATUS, &val);
 409	if (ret < 0) {
 410		dev_err(&ak8974->i2c->dev, "error reading DRDY status\n");
 411		return IRQ_HANDLED;
 412	}
 413	if (val & AK8974_STATUS_DRDY) {
 414		/* Yes this was our IRQ */
 415		complete(&ak8974->drdy_complete);
 416		return IRQ_HANDLED;
 417	}
 418
 419	/* We may be on a shared IRQ, let the next client check */
 420	return IRQ_NONE;
 421}
 422
 423static int ak8974_selftest(struct ak8974 *ak8974)
 424{
 425	struct device *dev = &ak8974->i2c->dev;
 426	unsigned int val;
 427	int ret;
 428
 429	ret = regmap_read(ak8974->map, AK8974_SELFTEST, &val);
 430	if (ret)
 431		return ret;
 432	if (val != AK8974_SELFTEST_IDLE) {
 433		dev_err(dev, "selftest not idle before test\n");
 434		return -EIO;
 435	}
 436
 437	/* Trigger self-test */
 438	ret = regmap_set_bits(ak8974->map, AK8974_CTRL3, AK8974_CTRL3_SELFTEST);
 439	if (ret) {
 440		dev_err(dev, "could not write CTRL3\n");
 441		return ret;
 442	}
 443
 444	msleep(AK8974_SELFTEST_DELAY);
 445
 446	ret = regmap_read(ak8974->map, AK8974_SELFTEST, &val);
 447	if (ret)
 448		return ret;
 449	if (val != AK8974_SELFTEST_OK) {
 450		dev_err(dev, "selftest result NOT OK (%02x)\n", val);
 451		return -EIO;
 452	}
 453
 454	ret = regmap_read(ak8974->map, AK8974_SELFTEST, &val);
 455	if (ret)
 456		return ret;
 457	if (val != AK8974_SELFTEST_IDLE) {
 458		dev_err(dev, "selftest not idle after test (%02x)\n", val);
 459		return -EIO;
 460	}
 461	dev_dbg(dev, "passed self-test\n");
 462
 463	return 0;
 464}
 465
 466static void ak8974_read_calib_data(struct ak8974 *ak8974, unsigned int reg,
 467				   __le16 *tab, size_t tab_size)
 468{
 469	int ret = regmap_bulk_read(ak8974->map, reg, tab, tab_size);
 470	if (ret) {
 471		memset(tab, 0xFF, tab_size);
 472		dev_warn(&ak8974->i2c->dev,
 473			 "can't read calibration data (regs %u..%zu): %d\n",
 474			 reg, reg + tab_size - 1, ret);
 475	} else {
 476		add_device_randomness(tab, tab_size);
 477	}
 478}
 479
 480static int ak8974_detect(struct ak8974 *ak8974)
 481{
 482	unsigned int whoami;
 483	const char *name;
 484	int ret;
 485	unsigned int fw;
 486	u16 sn;
 487
 488	ret = regmap_read(ak8974->map, AK8974_WHOAMI, &whoami);
 489	if (ret)
 490		return ret;
 491
 492	name = "ami305";
 493
 494	switch (whoami) {
 495	case AK8974_WHOAMI_VALUE_AMI306:
 496		name = "ami306";
 497		fallthrough;
 498	case AK8974_WHOAMI_VALUE_AMI305:
 499		ret = regmap_read(ak8974->map, AMI305_VER, &fw);
 500		if (ret)
 501			return ret;
 502		fw &= 0x7f; /* only bits 0 thru 6 valid */
 503		ret = ak8974_get_u16_val(ak8974, AMI305_SN, &sn);
 504		if (ret)
 505			return ret;
 506		add_device_randomness(&sn, sizeof(sn));
 507		dev_info(&ak8974->i2c->dev,
 508			 "detected %s, FW ver %02x, S/N: %04x\n",
 509			 name, fw, sn);
 510		break;
 511	case AK8974_WHOAMI_VALUE_AK8974:
 512		name = "ak8974";
 513		dev_info(&ak8974->i2c->dev, "detected AK8974\n");
 514		break;
 515	case AK8974_WHOAMI_VALUE_HSCDTD008A:
 516		name = "hscdtd008a";
 517		dev_info(&ak8974->i2c->dev, "detected hscdtd008a\n");
 518		break;
 519	default:
 520		dev_err(&ak8974->i2c->dev, "unsupported device (%02x) ",
 521			whoami);
 522		return -ENODEV;
 523	}
 524
 525	ak8974->name = name;
 526	ak8974->variant = whoami;
 527
 528	if (whoami == AK8974_WHOAMI_VALUE_AMI306) {
 529		__le16 fab_data1[9], fab_data2[3];
 530		int i;
 531
 532		ak8974_read_calib_data(ak8974, AMI306_FINEOUTPUT_X,
 533				       fab_data1, sizeof(fab_data1));
 534		ak8974_read_calib_data(ak8974, AMI306_OFFZERO_X,
 535				       fab_data2, sizeof(fab_data2));
 536
 537		for (i = 0; i < 3; ++i) {
 538			static const char axis[] = "XYZ";
 539			static const char pgaxis[] = "ZYZXYX";
 540			unsigned offz = le16_to_cpu(fab_data2[i]) & 0x7F;
 541			unsigned fine = le16_to_cpu(fab_data1[i]);
 542			unsigned sens = le16_to_cpu(fab_data1[i + 3]);
 543			unsigned pgain1 = le16_to_cpu(fab_data1[i + 6]);
 544			unsigned pgain2 = pgain1 >> 8;
 545
 546			pgain1 &= 0xFF;
 547
 548			dev_info(&ak8974->i2c->dev,
 549				 "factory calibration for axis %c: offz=%u sens=%u fine=%u pga%c=%u pga%c=%u\n",
 550				 axis[i], offz, sens, fine, pgaxis[i * 2],
 551				 pgain1, pgaxis[i * 2 + 1], pgain2);
 552		}
 553	}
 554
 555	return 0;
 556}
 557
 558static int ak8974_measure_channel(struct ak8974 *ak8974, unsigned long address,
 559				  int *val)
 560{
 561	__le16 hw_values[3];
 562	int ret;
 563
 564	pm_runtime_get_sync(&ak8974->i2c->dev);
 565	mutex_lock(&ak8974->lock);
 566
 567	/*
 568	 * We read all axes and discard all but one, for optimized
 569	 * reading, use the triggered buffer.
 570	 */
 571	ret = ak8974_trigmeas(ak8974);
 572	if (ret)
 573		goto out_unlock;
 574	ret = ak8974_getresult(ak8974, hw_values);
 575	if (ret)
 576		goto out_unlock;
 577	/*
 578	 * This explicit cast to (s16) is necessary as the measurement
 579	 * is done in 2's complement with positive and negative values.
 580	 * The follwing assignment to *val will then convert the signed
 581	 * s16 value to a signed int value.
 582	 */
 583	*val = (s16)le16_to_cpu(hw_values[address]);
 584out_unlock:
 585	mutex_unlock(&ak8974->lock);
 586	pm_runtime_put_autosuspend(&ak8974->i2c->dev);
 587
 588	return ret;
 589}
 590
 591static int ak8974_read_raw(struct iio_dev *indio_dev,
 592			   struct iio_chan_spec const *chan,
 593			   int *val, int *val2,
 594			   long mask)
 595{
 596	struct ak8974 *ak8974 = iio_priv(indio_dev);
 597	int ret;
 598
 599	switch (mask) {
 600	case IIO_CHAN_INFO_RAW:
 601		if (chan->address > 2) {
 602			dev_err(&ak8974->i2c->dev, "faulty channel address\n");
 603			return -EIO;
 604		}
 605		ret = ak8974_measure_channel(ak8974, chan->address, val);
 606		if (ret)
 607			return ret;
 608		return IIO_VAL_INT;
 609	case IIO_CHAN_INFO_SCALE:
 610		switch (ak8974->variant) {
 611		case AK8974_WHOAMI_VALUE_AMI306:
 612		case AK8974_WHOAMI_VALUE_AMI305:
 613			/*
 614			 * The datasheet for AMI305 and AMI306, page 6
 615			 * specifies the range of the sensor to be
 616			 * +/- 12 Gauss.
 617			 */
 618			*val = 12;
 619			/*
 620			 * 12 bits are used, +/- 2^11
 621			 * [ -2048 .. 2047 ] (manual page 20)
 622			 * [ 0xf800 .. 0x07ff ]
 623			 */
 624			*val2 = 11;
 625			return IIO_VAL_FRACTIONAL_LOG2;
 626		case AK8974_WHOAMI_VALUE_HSCDTD008A:
 627			/*
 628			 * The datasheet for HSCDTF008A, page 3 specifies the
 629			 * range of the sensor as +/- 2.4 mT per axis, which
 630			 * corresponds to +/- 2400 uT = +/- 24 Gauss.
 631			 */
 632			*val = 24;
 633			/*
 634			 * 15 bits are used (set up in CTRL4), +/- 2^14
 635			 * [ -16384 .. 16383 ] (manual page 24)
 636			 * [ 0xc000 .. 0x3fff ]
 637			 */
 638			*val2 = 14;
 639			return IIO_VAL_FRACTIONAL_LOG2;
 640		default:
 641			/* GUESSING +/- 12 Gauss */
 642			*val = 12;
 643			/* GUESSING 12 bits ADC +/- 2^11 */
 644			*val2 = 11;
 645			return IIO_VAL_FRACTIONAL_LOG2;
 646		}
 647		break;
 648	default:
 649		/* Unknown request */
 650		break;
 651	}
 652
 653	return -EINVAL;
 654}
 655
 656static void ak8974_fill_buffer(struct iio_dev *indio_dev)
 657{
 658	struct ak8974 *ak8974 = iio_priv(indio_dev);
 659	int ret;
 660
 661	pm_runtime_get_sync(&ak8974->i2c->dev);
 662	mutex_lock(&ak8974->lock);
 663
 664	ret = ak8974_trigmeas(ak8974);
 665	if (ret) {
 666		dev_err(&ak8974->i2c->dev, "error triggering measure\n");
 667		goto out_unlock;
 668	}
 669	ret = ak8974_getresult(ak8974, ak8974->scan.channels);
 670	if (ret) {
 671		dev_err(&ak8974->i2c->dev, "error getting measures\n");
 672		goto out_unlock;
 673	}
 674
 675	iio_push_to_buffers_with_ts(indio_dev, &ak8974->scan, sizeof(ak8974->scan),
 676				    iio_get_time_ns(indio_dev));
 677
 678 out_unlock:
 679	mutex_unlock(&ak8974->lock);
 680	pm_runtime_put_autosuspend(&ak8974->i2c->dev);
 681}
 682
 683static irqreturn_t ak8974_handle_trigger(int irq, void *p)
 684{
 685	const struct iio_poll_func *pf = p;
 686	struct iio_dev *indio_dev = pf->indio_dev;
 687
 688	ak8974_fill_buffer(indio_dev);
 689	iio_trigger_notify_done(indio_dev->trig);
 690
 691	return IRQ_HANDLED;
 692}
 693
 694static const struct iio_mount_matrix *
 695ak8974_get_mount_matrix(const struct iio_dev *indio_dev,
 696			const struct iio_chan_spec *chan)
 697{
 698	struct ak8974 *ak8974 = iio_priv(indio_dev);
 699
 700	return &ak8974->orientation;
 701}
 702
 703static const struct iio_chan_spec_ext_info ak8974_ext_info[] = {
 704	IIO_MOUNT_MATRIX(IIO_SHARED_BY_DIR, ak8974_get_mount_matrix),
 705	{ }
 706};
 707
 708#define AK8974_AXIS_CHANNEL(axis, index, bits)				\
 709	{								\
 710		.type = IIO_MAGN,					\
 711		.modified = 1,						\
 712		.channel2 = IIO_MOD_##axis,				\
 713		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |		\
 714			BIT(IIO_CHAN_INFO_SCALE),			\
 715		.ext_info = ak8974_ext_info,				\
 716		.address = index,					\
 717		.scan_index = index,					\
 718		.scan_type = {						\
 719			.sign = 's',					\
 720			.realbits = bits,				\
 721			.storagebits = 16,				\
 722			.endianness = IIO_LE				\
 723		},							\
 724	}
 725
 726/*
 727 * We have no datasheet for the AK8974 but we guess that its
 728 * ADC is 12 bits. The AMI305 and AMI306 certainly has 12bit
 729 * ADC.
 730 */
 731static const struct iio_chan_spec ak8974_12_bits_channels[] = {
 732	AK8974_AXIS_CHANNEL(X, 0, 12),
 733	AK8974_AXIS_CHANNEL(Y, 1, 12),
 734	AK8974_AXIS_CHANNEL(Z, 2, 12),
 735	IIO_CHAN_SOFT_TIMESTAMP(3),
 736};
 737
 738/*
 739 * The HSCDTD008A has 15 bits resolution the way we set it up
 740 * in CTRL4.
 741 */
 742static const struct iio_chan_spec ak8974_15_bits_channels[] = {
 743	AK8974_AXIS_CHANNEL(X, 0, 15),
 744	AK8974_AXIS_CHANNEL(Y, 1, 15),
 745	AK8974_AXIS_CHANNEL(Z, 2, 15),
 746	IIO_CHAN_SOFT_TIMESTAMP(3),
 747};
 748
 749static const unsigned long ak8974_scan_masks[] = { 0x7, 0 };
 750
 751static const struct iio_info ak8974_info = {
 752	.read_raw = &ak8974_read_raw,
 753};
 754
 755static bool ak8974_writeable_reg(struct device *dev, unsigned int reg)
 756{
 757	struct i2c_client *i2c = to_i2c_client(dev);
 758	struct iio_dev *indio_dev = i2c_get_clientdata(i2c);
 759	struct ak8974 *ak8974 = iio_priv(indio_dev);
 760
 761	switch (reg) {
 762	case AK8974_CTRL1:
 763	case AK8974_CTRL2:
 764	case AK8974_CTRL3:
 765	case AK8974_INT_CTRL:
 766	case AK8974_INT_THRES:
 767	case AK8974_INT_THRES + 1:
 768		return true;
 769	case AK8974_PRESET:
 770	case AK8974_PRESET + 1:
 771		return ak8974->variant != AK8974_WHOAMI_VALUE_HSCDTD008A;
 772	case AK8974_OFFSET_X:
 773	case AK8974_OFFSET_X + 1:
 774	case AK8974_OFFSET_Y:
 775	case AK8974_OFFSET_Y + 1:
 776	case AK8974_OFFSET_Z:
 777	case AK8974_OFFSET_Z + 1:
 778		return ak8974->variant == AK8974_WHOAMI_VALUE_AK8974 ||
 779		       ak8974->variant == AK8974_WHOAMI_VALUE_HSCDTD008A;
 780	case AMI305_OFFSET_X:
 781	case AMI305_OFFSET_X + 1:
 782	case AMI305_OFFSET_Y:
 783	case AMI305_OFFSET_Y + 1:
 784	case AMI305_OFFSET_Z:
 785	case AMI305_OFFSET_Z + 1:
 786		return ak8974->variant == AK8974_WHOAMI_VALUE_AMI305 ||
 787		       ak8974->variant == AK8974_WHOAMI_VALUE_AMI306;
 788	case AMI306_CTRL4:
 789	case AMI306_CTRL4 + 1:
 790		return ak8974->variant == AK8974_WHOAMI_VALUE_AMI306;
 791	default:
 792		return false;
 793	}
 794}
 795
 796static bool ak8974_precious_reg(struct device *dev, unsigned int reg)
 797{
 798	return reg == AK8974_INT_CLEAR;
 799}
 800
 801static const struct regmap_config ak8974_regmap_config = {
 802	.reg_bits = 8,
 803	.val_bits = 8,
 804	.max_register = 0xff,
 805	.writeable_reg = ak8974_writeable_reg,
 806	.precious_reg = ak8974_precious_reg,
 807};
 808
 809static int ak8974_probe(struct i2c_client *i2c)
 810{
 811	struct iio_dev *indio_dev;
 812	struct ak8974 *ak8974;
 813	unsigned long irq_trig;
 814	int irq = i2c->irq;
 815	int ret;
 816
 817	/* Register with IIO */
 818	indio_dev = devm_iio_device_alloc(&i2c->dev, sizeof(*ak8974));
 819	if (indio_dev == NULL)
 820		return -ENOMEM;
 821
 822	ak8974 = iio_priv(indio_dev);
 823	i2c_set_clientdata(i2c, indio_dev);
 824	ak8974->i2c = i2c;
 825	mutex_init(&ak8974->lock);
 826
 827	ret = iio_read_mount_matrix(&i2c->dev, &ak8974->orientation);
 828	if (ret)
 829		return ret;
 830
 831	ak8974->regs[0].supply = ak8974_reg_avdd;
 832	ak8974->regs[1].supply = ak8974_reg_dvdd;
 833
 834	ret = devm_regulator_bulk_get(&i2c->dev,
 835				      ARRAY_SIZE(ak8974->regs),
 836				      ak8974->regs);
 837	if (ret < 0)
 838		return dev_err_probe(&i2c->dev, ret, "cannot get regulators\n");
 839
 840	ret = regulator_bulk_enable(ARRAY_SIZE(ak8974->regs), ak8974->regs);
 841	if (ret < 0) {
 842		dev_err(&i2c->dev, "cannot enable regulators\n");
 843		return ret;
 844	}
 845
 846	/* Take runtime PM online */
 847	pm_runtime_get_noresume(&i2c->dev);
 848	pm_runtime_set_active(&i2c->dev);
 849	pm_runtime_enable(&i2c->dev);
 850
 851	ak8974->map = devm_regmap_init_i2c(i2c, &ak8974_regmap_config);
 852	if (IS_ERR(ak8974->map)) {
 853		dev_err(&i2c->dev, "failed to allocate register map\n");
 854		pm_runtime_put_noidle(&i2c->dev);
 855		pm_runtime_disable(&i2c->dev);
 856		return PTR_ERR(ak8974->map);
 857	}
 858
 859	ret = ak8974_set_power(ak8974, AK8974_PWR_ON);
 860	if (ret) {
 861		dev_err(&i2c->dev, "could not power on\n");
 862		goto disable_pm;
 863	}
 864
 865	ret = ak8974_detect(ak8974);
 866	if (ret) {
 867		dev_err(&i2c->dev, "neither AK8974 nor AMI30x found\n");
 868		goto disable_pm;
 869	}
 870
 871	ret = ak8974_selftest(ak8974);
 872	if (ret)
 873		dev_err(&i2c->dev, "selftest failed (continuing anyway)\n");
 874
 875	ret = ak8974_reset(ak8974);
 876	if (ret) {
 877		dev_err(&i2c->dev, "AK8974 reset failed\n");
 878		goto disable_pm;
 879	}
 880
 881	switch (ak8974->variant) {
 882	case AK8974_WHOAMI_VALUE_AMI306:
 883	case AK8974_WHOAMI_VALUE_AMI305:
 884		indio_dev->channels = ak8974_12_bits_channels;
 885		indio_dev->num_channels = ARRAY_SIZE(ak8974_12_bits_channels);
 886		break;
 887	case AK8974_WHOAMI_VALUE_HSCDTD008A:
 888		indio_dev->channels = ak8974_15_bits_channels;
 889		indio_dev->num_channels = ARRAY_SIZE(ak8974_15_bits_channels);
 890		break;
 891	default:
 892		indio_dev->channels = ak8974_12_bits_channels;
 893		indio_dev->num_channels = ARRAY_SIZE(ak8974_12_bits_channels);
 894		break;
 895	}
 896	indio_dev->info = &ak8974_info;
 897	indio_dev->available_scan_masks = ak8974_scan_masks;
 898	indio_dev->modes = INDIO_DIRECT_MODE;
 899	indio_dev->name = ak8974->name;
 900
 901	ret = iio_triggered_buffer_setup(indio_dev, NULL,
 902					 ak8974_handle_trigger,
 903					 NULL);
 904	if (ret) {
 905		dev_err(&i2c->dev, "triggered buffer setup failed\n");
 906		goto disable_pm;
 907	}
 908
 909	/* If we have a valid DRDY IRQ, make use of it */
 910	if (irq > 0) {
 911		irq_trig = irq_get_trigger_type(irq);
 912		if (irq_trig == IRQF_TRIGGER_RISING) {
 913			dev_info(&i2c->dev, "enable rising edge DRDY IRQ\n");
 914		} else if (irq_trig == IRQF_TRIGGER_FALLING) {
 915			ak8974->drdy_active_low = true;
 916			dev_info(&i2c->dev, "enable falling edge DRDY IRQ\n");
 917		} else {
 918			irq_trig = IRQF_TRIGGER_RISING;
 919		}
 920		irq_trig |= IRQF_ONESHOT;
 921		irq_trig |= IRQF_SHARED;
 922
 923		ret = devm_request_threaded_irq(&i2c->dev,
 924						irq,
 925						ak8974_drdy_irq,
 926						ak8974_drdy_irq_thread,
 927						irq_trig,
 928						ak8974->name,
 929						ak8974);
 930		if (ret) {
 931			dev_err(&i2c->dev, "unable to request DRDY IRQ "
 932				"- proceeding without IRQ\n");
 933			goto no_irq;
 934		}
 935		ak8974->drdy_irq = true;
 936	}
 937
 938no_irq:
 939	ret = iio_device_register(indio_dev);
 940	if (ret) {
 941		dev_err(&i2c->dev, "device register failed\n");
 942		goto cleanup_buffer;
 943	}
 944
 945	pm_runtime_set_autosuspend_delay(&i2c->dev,
 946					 AK8974_AUTOSUSPEND_DELAY);
 947	pm_runtime_use_autosuspend(&i2c->dev);
 948	pm_runtime_put(&i2c->dev);
 949
 950	return 0;
 951
 952cleanup_buffer:
 953	iio_triggered_buffer_cleanup(indio_dev);
 954disable_pm:
 955	pm_runtime_put_noidle(&i2c->dev);
 956	pm_runtime_disable(&i2c->dev);
 957	ak8974_set_power(ak8974, AK8974_PWR_OFF);
 958	regulator_bulk_disable(ARRAY_SIZE(ak8974->regs), ak8974->regs);
 959
 960	return ret;
 961}
 962
 963static void ak8974_remove(struct i2c_client *i2c)
 964{
 965	struct iio_dev *indio_dev = i2c_get_clientdata(i2c);
 966	struct ak8974 *ak8974 = iio_priv(indio_dev);
 967
 968	iio_device_unregister(indio_dev);
 969	iio_triggered_buffer_cleanup(indio_dev);
 970	pm_runtime_get_sync(&i2c->dev);
 971	pm_runtime_put_noidle(&i2c->dev);
 972	pm_runtime_disable(&i2c->dev);
 973	ak8974_set_power(ak8974, AK8974_PWR_OFF);
 974	regulator_bulk_disable(ARRAY_SIZE(ak8974->regs), ak8974->regs);
 975}
 976
 977static int ak8974_runtime_suspend(struct device *dev)
 978{
 979	struct ak8974 *ak8974 =
 980		iio_priv(i2c_get_clientdata(to_i2c_client(dev)));
 981
 982	ak8974_set_power(ak8974, AK8974_PWR_OFF);
 983	regulator_bulk_disable(ARRAY_SIZE(ak8974->regs), ak8974->regs);
 984
 985	return 0;
 986}
 987
 988static int ak8974_runtime_resume(struct device *dev)
 989{
 990	struct ak8974 *ak8974 =
 991		iio_priv(i2c_get_clientdata(to_i2c_client(dev)));
 992	int ret;
 993
 994	ret = regulator_bulk_enable(ARRAY_SIZE(ak8974->regs), ak8974->regs);
 995	if (ret)
 996		return ret;
 997	msleep(AK8974_POWERON_DELAY);
 998	ret = ak8974_set_power(ak8974, AK8974_PWR_ON);
 999	if (ret)
1000		goto out_regulator_disable;
1001
1002	ret = ak8974_configure(ak8974);
1003	if (ret)
1004		goto out_disable_power;
1005
1006	return 0;
1007
1008out_disable_power:
1009	ak8974_set_power(ak8974, AK8974_PWR_OFF);
1010out_regulator_disable:
1011	regulator_bulk_disable(ARRAY_SIZE(ak8974->regs), ak8974->regs);
1012
1013	return ret;
1014}
1015
1016static DEFINE_RUNTIME_DEV_PM_OPS(ak8974_dev_pm_ops, ak8974_runtime_suspend,
1017				 ak8974_runtime_resume, NULL);
1018
1019static const struct i2c_device_id ak8974_id[] = {
1020	{ "ami305" },
1021	{ "ami306" },
1022	{ "ak8974" },
1023	{ "hscdtd008a" },
1024	{ }
1025};
1026MODULE_DEVICE_TABLE(i2c, ak8974_id);
1027
1028static const struct of_device_id ak8974_of_match[] = {
1029	{ .compatible = "asahi-kasei,ak8974", },
1030	{ .compatible = "alps,hscdtd008a", },
1031	{ }
1032};
1033MODULE_DEVICE_TABLE(of, ak8974_of_match);
1034
1035static struct i2c_driver ak8974_driver = {
1036	.driver	 = {
1037		.name	= "ak8974",
1038		.pm = pm_ptr(&ak8974_dev_pm_ops),
1039		.of_match_table = ak8974_of_match,
1040	},
1041	.probe = ak8974_probe,
1042	.remove	  = ak8974_remove,
1043	.id_table = ak8974_id,
1044};
1045module_i2c_driver(ak8974_driver);
1046
1047MODULE_DESCRIPTION("AK8974 and AMI30x 3-axis magnetometer driver");
1048MODULE_AUTHOR("Samu Onkalo");
1049MODULE_AUTHOR("Linus Walleij");
1050MODULE_LICENSE("GPL v2");