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PM / sleep: Asynchronous threads for suspend_noirq
[linux/fpc-iii.git] / drivers / iio / magnetometer / ak8975.c
blob05423543f89d7896ba1a6f086b409955c35417fa
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
35 #include <linux/iio/iio.h>
36 #include <linux/iio/sysfs.h>
37 /*
38 * Register definitions, as well as various shifts and masks to get at the
39 * individual fields of the registers.
40 */
41 #define AK8975_REG_WIA 0x00
42 #define AK8975_DEVICE_ID 0x48
43
44 #define AK8975_REG_INFO 0x01
45
46 #define AK8975_REG_ST1 0x02
47 #define AK8975_REG_ST1_DRDY_SHIFT 0
48 #define AK8975_REG_ST1_DRDY_MASK (1 << AK8975_REG_ST1_DRDY_SHIFT)
49
50 #define AK8975_REG_HXL 0x03
51 #define AK8975_REG_HXH 0x04
52 #define AK8975_REG_HYL 0x05
53 #define AK8975_REG_HYH 0x06
54 #define AK8975_REG_HZL 0x07
55 #define AK8975_REG_HZH 0x08
56 #define AK8975_REG_ST2 0x09
57 #define AK8975_REG_ST2_DERR_SHIFT 2
58 #define AK8975_REG_ST2_DERR_MASK (1 << AK8975_REG_ST2_DERR_SHIFT)
59
60 #define AK8975_REG_ST2_HOFL_SHIFT 3
61 #define AK8975_REG_ST2_HOFL_MASK (1 << AK8975_REG_ST2_HOFL_SHIFT)
62
63 #define AK8975_REG_CNTL 0x0A
64 #define AK8975_REG_CNTL_MODE_SHIFT 0
65 #define AK8975_REG_CNTL_MODE_MASK (0xF << AK8975_REG_CNTL_MODE_SHIFT)
66 #define AK8975_REG_CNTL_MODE_POWER_DOWN 0
67 #define AK8975_REG_CNTL_MODE_ONCE 1
68 #define AK8975_REG_CNTL_MODE_SELF_TEST 8
69 #define AK8975_REG_CNTL_MODE_FUSE_ROM 0xF
70
71 #define AK8975_REG_RSVC 0x0B
72 #define AK8975_REG_ASTC 0x0C
73 #define AK8975_REG_TS1 0x0D
74 #define AK8975_REG_TS2 0x0E
75 #define AK8975_REG_I2CDIS 0x0F
76 #define AK8975_REG_ASAX 0x10
77 #define AK8975_REG_ASAY 0x11
78 #define AK8975_REG_ASAZ 0x12
79
80 #define AK8975_MAX_REGS AK8975_REG_ASAZ
81
82 /*
83 * Miscellaneous values.
84 */
85 #define AK8975_MAX_CONVERSION_TIMEOUT 500
86 #define AK8975_CONVERSION_DONE_POLL_TIME 10
87 #define AK8975_DATA_READY_TIMEOUT ((100*HZ)/1000)
88 #define RAW_TO_GAUSS(asa) ((((asa) + 128) * 3000) / 256)
89
90 /*
91 * Per-instance context data for the device.
92 */
93 struct ak8975_data {
94 struct i2c_client *client;
95 struct attribute_group attrs;
96 struct mutex lock;
97 u8 asa[3];
98 long raw_to_gauss[3];
99 u8 reg_cache[AK8975_MAX_REGS];
100 int eoc_gpio;
101 int eoc_irq;
102 wait_queue_head_t data_ready_queue;
103 unsigned long flags;
104 };
105
106 static const int ak8975_index_to_reg[] = {
107 AK8975_REG_HXL, AK8975_REG_HYL, AK8975_REG_HZL,
108 };
109
110 /*
111 * Helper function to write to the I2C device's registers.
112 */
113 static int ak8975_write_data(struct i2c_client *client,
114 u8 reg, u8 val, u8 mask, u8 shift)
115 {
116 struct iio_dev *indio_dev = i2c_get_clientdata(client);
117 struct ak8975_data *data = iio_priv(indio_dev);
118 u8 regval;
119 int ret;
120
121 regval = (data->reg_cache[reg] & ~mask) | (val << shift);
122 ret = i2c_smbus_write_byte_data(client, reg, regval);
123 if (ret < 0) {
124 dev_err(&client->dev, "Write to device fails status %x\n", ret);
125 return ret;
126 }
127 data->reg_cache[reg] = regval;
128
129 return 0;
130 }
131
132 /*
133 * Handle data ready irq
134 */
135 static irqreturn_t ak8975_irq_handler(int irq, void *data)
136 {
137 struct ak8975_data *ak8975 = data;
138
139 set_bit(0, &ak8975->flags);
140 wake_up(&ak8975->data_ready_queue);
141
142 return IRQ_HANDLED;
143 }
144
145 /*
146 * Install data ready interrupt handler
147 */
148 static int ak8975_setup_irq(struct ak8975_data *data)
149 {
150 struct i2c_client *client = data->client;
151 int rc;
152 int irq;
153
154 if (client->irq)
155 irq = client->irq;
156 else
157 irq = gpio_to_irq(data->eoc_gpio);
158
159 rc = request_irq(irq, ak8975_irq_handler,
160 IRQF_TRIGGER_RISING | IRQF_ONESHOT,
161 dev_name(&client->dev), data);
162 if (rc < 0) {
163 dev_err(&client->dev,
164 "irq %d request failed, (gpio %d): %d\n",
165 irq, data->eoc_gpio, rc);
166 return rc;
167 }
168
169 init_waitqueue_head(&data->data_ready_queue);
170 clear_bit(0, &data->flags);
171 data->eoc_irq = irq;
172
173 return rc;
174 }
175
176
177 /*
178 * Perform some start-of-day setup, including reading the asa calibration
179 * values and caching them.
180 */
181 static int ak8975_setup(struct i2c_client *client)
182 {
183 struct iio_dev *indio_dev = i2c_get_clientdata(client);
184 struct ak8975_data *data = iio_priv(indio_dev);
185 u8 device_id;
186 int ret;
187
188 /* Confirm that the device we're talking to is really an AK8975. */
189 ret = i2c_smbus_read_byte_data(client, AK8975_REG_WIA);
190 if (ret < 0) {
191 dev_err(&client->dev, "Error reading WIA\n");
192 return ret;
193 }
194 device_id = ret;
195 if (device_id != AK8975_DEVICE_ID) {
196 dev_err(&client->dev, "Device ak8975 not found\n");
197 return -ENODEV;
198 }
199
200 /* Write the fused rom access mode. */
201 ret = ak8975_write_data(client,
202 AK8975_REG_CNTL,
203 AK8975_REG_CNTL_MODE_FUSE_ROM,
204 AK8975_REG_CNTL_MODE_MASK,
205 AK8975_REG_CNTL_MODE_SHIFT);
206 if (ret < 0) {
207 dev_err(&client->dev, "Error in setting fuse access mode\n");
208 return ret;
209 }
210
211 /* Get asa data and store in the device data. */
212 ret = i2c_smbus_read_i2c_block_data(client, AK8975_REG_ASAX,
213 3, data->asa);
214 if (ret < 0) {
215 dev_err(&client->dev, "Not able to read asa data\n");
216 return ret;
217 }
218
219 /* After reading fuse ROM data set power-down mode */
220 ret = ak8975_write_data(client,
221 AK8975_REG_CNTL,
222 AK8975_REG_CNTL_MODE_POWER_DOWN,
223 AK8975_REG_CNTL_MODE_MASK,
224 AK8975_REG_CNTL_MODE_SHIFT);
225
226 if (data->eoc_gpio > 0 || client->irq) {
227 ret = ak8975_setup_irq(data);
228 if (ret < 0) {
229 dev_err(&client->dev,
230 "Error setting data ready interrupt\n");
231 return ret;
232 }
233 }
234
235 if (ret < 0) {
236 dev_err(&client->dev, "Error in setting power-down mode\n");
237 return ret;
238 }
239
240 /*
241 * Precalculate scale factor (in Gauss units) for each axis and
242 * store in the device data.
243 *
244 * This scale factor is axis-dependent, and is derived from 3 calibration
245 * factors ASA(x), ASA(y), and ASA(z).
246 *
247 * These ASA values are read from the sensor device at start of day, and
248 * cached in the device context struct.
249 *
250 * Adjusting the flux value with the sensitivity adjustment value should be
251 * done via the following formula:
252 *
253 * Hadj = H * ( ( ( (ASA-128)*0.5 ) / 128 ) + 1 )
254 *
255 * where H is the raw value, ASA is the sensitivity adjustment, and Hadj
256 * is the resultant adjusted value.
257 *
258 * We reduce the formula to:
259 *
260 * Hadj = H * (ASA + 128) / 256
261 *
262 * H is in the range of -4096 to 4095. The magnetometer has a range of
263 * +-1229uT. To go from the raw value to uT is:
264 *
265 * HuT = H * 1229/4096, or roughly, 3/10.
266 *
267 * Since 1uT = 0.01 gauss, our final scale factor becomes:
268 *
269 * Hadj = H * ((ASA + 128) / 256) * 3/10 * 1/100
270 * Hadj = H * ((ASA + 128) * 0.003) / 256
271 *
272 * Since ASA doesn't change, we cache the resultant scale factor into the
273 * device context in ak8975_setup().
274 */
275 data->raw_to_gauss[0] = RAW_TO_GAUSS(data->asa[0]);
276 data->raw_to_gauss[1] = RAW_TO_GAUSS(data->asa[1]);
277 data->raw_to_gauss[2] = RAW_TO_GAUSS(data->asa[2]);
278
279 return 0;
280 }
281
282 static int wait_conversion_complete_gpio(struct ak8975_data *data)
283 {
284 struct i2c_client *client = data->client;
285 u32 timeout_ms = AK8975_MAX_CONVERSION_TIMEOUT;
286 int ret;
287
288 /* Wait for the conversion to complete. */
289 while (timeout_ms) {
290 msleep(AK8975_CONVERSION_DONE_POLL_TIME);
291 if (gpio_get_value(data->eoc_gpio))
292 break;
293 timeout_ms -= AK8975_CONVERSION_DONE_POLL_TIME;
294 }
295 if (!timeout_ms) {
296 dev_err(&client->dev, "Conversion timeout happened\n");
297 return -EINVAL;
298 }
299
300 ret = i2c_smbus_read_byte_data(client, AK8975_REG_ST1);
301 if (ret < 0)
302 dev_err(&client->dev, "Error in reading ST1\n");
303
304 return ret;
305 }
306
307 static int wait_conversion_complete_polled(struct ak8975_data *data)
308 {
309 struct i2c_client *client = data->client;
310 u8 read_status;
311 u32 timeout_ms = AK8975_MAX_CONVERSION_TIMEOUT;
312 int ret;
313
314 /* Wait for the conversion to complete. */
315 while (timeout_ms) {
316 msleep(AK8975_CONVERSION_DONE_POLL_TIME);
317 ret = i2c_smbus_read_byte_data(client, AK8975_REG_ST1);
318 if (ret < 0) {
319 dev_err(&client->dev, "Error in reading ST1\n");
320 return ret;
321 }
322 read_status = ret;
323 if (read_status)
324 break;
325 timeout_ms -= AK8975_CONVERSION_DONE_POLL_TIME;
326 }
327 if (!timeout_ms) {
328 dev_err(&client->dev, "Conversion timeout happened\n");
329 return -EINVAL;
330 }
331
332 return read_status;
333 }
334
335 /* Returns 0 if the end of conversion interrupt occured or -ETIME otherwise */
336 static int wait_conversion_complete_interrupt(struct ak8975_data *data)
337 {
338 int ret;
339
340 ret = wait_event_timeout(data->data_ready_queue,
341 test_bit(0, &data->flags),
342 AK8975_DATA_READY_TIMEOUT);
343 clear_bit(0, &data->flags);
344
345 return ret > 0 ? 0 : -ETIME;
346 }
347
348 /*
349 * Emits the raw flux value for the x, y, or z axis.
350 */
351 static int ak8975_read_axis(struct iio_dev *indio_dev, int index, int *val)
352 {
353 struct ak8975_data *data = iio_priv(indio_dev);
354 struct i2c_client *client = data->client;
355 u16 meas_reg;
356 s16 raw;
357 int ret;
358
359 mutex_lock(&data->lock);
360
361 /* Set up the device for taking a sample. */
362 ret = ak8975_write_data(client,
363 AK8975_REG_CNTL,
364 AK8975_REG_CNTL_MODE_ONCE,
365 AK8975_REG_CNTL_MODE_MASK,
366 AK8975_REG_CNTL_MODE_SHIFT);
367 if (ret < 0) {
368 dev_err(&client->dev, "Error in setting operating mode\n");
369 goto exit;
370 }
371
372 /* Wait for the conversion to complete. */
373 if (data->eoc_irq)
374 ret = wait_conversion_complete_interrupt(data);
375 else if (gpio_is_valid(data->eoc_gpio))
376 ret = wait_conversion_complete_gpio(data);
377 else
378 ret = wait_conversion_complete_polled(data);
379 if (ret < 0)
380 goto exit;
381
382 /* This will be executed only for non-interrupt based waiting case */
383 if (ret & AK8975_REG_ST1_DRDY_MASK) {
384 ret = i2c_smbus_read_byte_data(client, AK8975_REG_ST2);
385 if (ret < 0) {
386 dev_err(&client->dev, "Error in reading ST2\n");
387 goto exit;
388 }
389 if (ret & (AK8975_REG_ST2_DERR_MASK |
390 AK8975_REG_ST2_HOFL_MASK)) {
391 dev_err(&client->dev, "ST2 status error 0x%x\n", ret);
392 ret = -EINVAL;
393 goto exit;
394 }
395 }
396
397 /* Read the flux value from the appropriate register
398 (the register is specified in the iio device attributes). */
399 ret = i2c_smbus_read_word_data(client, ak8975_index_to_reg[index]);
400 if (ret < 0) {
401 dev_err(&client->dev, "Read axis data fails\n");
402 goto exit;
403 }
404 meas_reg = ret;
405
406 mutex_unlock(&data->lock);
407
408 /* Endian conversion of the measured values. */
409 raw = (s16) (le16_to_cpu(meas_reg));
410
411 /* Clamp to valid range. */
412 raw = clamp_t(s16, raw, -4096, 4095);
413 *val = raw;
414 return IIO_VAL_INT;
415
416 exit:
417 mutex_unlock(&data->lock);
418 return ret;
419 }
420
421 static int ak8975_read_raw(struct iio_dev *indio_dev,
422 struct iio_chan_spec const *chan,
423 int *val, int *val2,
424 long mask)
425 {
426 struct ak8975_data *data = iio_priv(indio_dev);
427
428 switch (mask) {
429 case IIO_CHAN_INFO_RAW:
430 return ak8975_read_axis(indio_dev, chan->address, val);
431 case IIO_CHAN_INFO_SCALE:
432 *val = 0;
433 *val2 = data->raw_to_gauss[chan->address];
434 return IIO_VAL_INT_PLUS_MICRO;
435 }
436 return -EINVAL;
437 }
438
439 #define AK8975_CHANNEL(axis, index) \
440 { \
441 .type = IIO_MAGN, \
442 .modified = 1, \
443 .channel2 = IIO_MOD_##axis, \
444 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \
445 BIT(IIO_CHAN_INFO_SCALE), \
446 .address = index, \
447 }
448
449 static const struct iio_chan_spec ak8975_channels[] = {
450 AK8975_CHANNEL(X, 0), AK8975_CHANNEL(Y, 1), AK8975_CHANNEL(Z, 2),
451 };
452
453 static const struct iio_info ak8975_info = {
454 .read_raw = &ak8975_read_raw,
455 .driver_module = THIS_MODULE,
456 };
457
458 static int ak8975_probe(struct i2c_client *client,
459 const struct i2c_device_id *id)
460 {
461 struct ak8975_data *data;
462 struct iio_dev *indio_dev;
463 int eoc_gpio;
464 int err;
465
466 /* Grab and set up the supplied GPIO. */
467 if (client->dev.platform_data)
468 eoc_gpio = *(int *)(client->dev.platform_data);
469 else if (client->dev.of_node)
470 eoc_gpio = of_get_gpio(client->dev.of_node, 0);
471 else
472 eoc_gpio = -1;
473
474 if (eoc_gpio == -EPROBE_DEFER)
475 return -EPROBE_DEFER;
476
477 /* We may not have a GPIO based IRQ to scan, that is fine, we will
478 poll if so */
479 if (gpio_is_valid(eoc_gpio)) {
480 err = gpio_request_one(eoc_gpio, GPIOF_IN, "ak_8975");
481 if (err < 0) {
482 dev_err(&client->dev,
483 "failed to request GPIO %d, error %d\n",
484 eoc_gpio, err);
485 goto exit;
486 }
487 }
488
489 /* Register with IIO */
490 indio_dev = iio_device_alloc(sizeof(*data));
491 if (indio_dev == NULL) {
492 err = -ENOMEM;
493 goto exit_gpio;
494 }
495 data = iio_priv(indio_dev);
496 i2c_set_clientdata(client, indio_dev);
497
498 data->client = client;
499 data->eoc_gpio = eoc_gpio;
500 data->eoc_irq = 0;
501
502 /* Perform some basic start-of-day setup of the device. */
503 err = ak8975_setup(client);
504 if (err < 0) {
505 dev_err(&client->dev, "AK8975 initialization fails\n");
506 goto exit_free_iio;
507 }
508
509 data->client = client;
510 mutex_init(&data->lock);
511 data->eoc_gpio = eoc_gpio;
512 indio_dev->dev.parent = &client->dev;
513 indio_dev->channels = ak8975_channels;
514 indio_dev->num_channels = ARRAY_SIZE(ak8975_channels);
515 indio_dev->info = &ak8975_info;
516 indio_dev->modes = INDIO_DIRECT_MODE;
517
518 err = iio_device_register(indio_dev);
519 if (err < 0)
520 goto exit_free_iio;
521
522 return 0;
523
524 exit_free_iio:
525 iio_device_free(indio_dev);
526 if (data->eoc_irq)
527 free_irq(data->eoc_irq, data);
528 exit_gpio:
529 if (gpio_is_valid(eoc_gpio))
530 gpio_free(eoc_gpio);
531 exit:
532 return err;
533 }
534
535 static int ak8975_remove(struct i2c_client *client)
536 {
537 struct iio_dev *indio_dev = i2c_get_clientdata(client);
538 struct ak8975_data *data = iio_priv(indio_dev);
539
540 iio_device_unregister(indio_dev);
541
542 if (data->eoc_irq)
543 free_irq(data->eoc_irq, data);
544
545 if (gpio_is_valid(data->eoc_gpio))
546 gpio_free(data->eoc_gpio);
547
548 iio_device_free(indio_dev);
549
550 return 0;
551 }
552
553 static const struct i2c_device_id ak8975_id[] = {
554 {"ak8975", 0},
555 {}
556 };
557
558 MODULE_DEVICE_TABLE(i2c, ak8975_id);
559
560 static const struct of_device_id ak8975_of_match[] = {
561 { .compatible = "asahi-kasei,ak8975", },
562 { .compatible = "ak8975", },
563 { }
564 };
565 MODULE_DEVICE_TABLE(of, ak8975_of_match);
566
567 static struct i2c_driver ak8975_driver = {
568 .driver = {
569 .name = "ak8975",
570 .of_match_table = ak8975_of_match,
571 },
572 .probe = ak8975_probe,
573 .remove = ak8975_remove,
574 .id_table = ak8975_id,
575 };
576 module_i2c_driver(ak8975_driver);
577
578 MODULE_AUTHOR("Laxman Dewangan <ldewangan@nvidia.com>");
579 MODULE_DESCRIPTION("AK8975 magnetometer driver");
580 MODULE_LICENSE("GPL");
Linux with added FPC-III support