2 * A sensor driver for the magnetometer AK8975.
4 * Magnetic compass sensor driver for monitoring magnetic flux information.
6 * Copyright (c) 2010, NVIDIA Corporation.
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.
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
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.
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>
36 #include <linux/iio/iio.h>
37 #include <linux/iio/sysfs.h>
39 * Register definitions, as well as various shifts and masks to get at the
40 * individual fields of the registers.
42 #define AK8975_REG_WIA 0x00
43 #define AK8975_DEVICE_ID 0x48
45 #define AK8975_REG_INFO 0x01
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)
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)
61 #define AK8975_REG_ST2_HOFL_SHIFT 3
62 #define AK8975_REG_ST2_HOFL_MASK (1 << AK8975_REG_ST2_HOFL_SHIFT)
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
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
81 #define AK8975_MAX_REGS AK8975_REG_ASAZ
84 * Miscellaneous values.
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)
92 /* Compatible Asahi Kasei Compass parts */
93 enum asahi_compass_chipset
{
99 * Per-instance context data for the device.
102 struct i2c_client
*client
;
103 struct attribute_group attrs
;
106 long raw_to_gauss
[3];
107 u8 reg_cache
[AK8975_MAX_REGS
];
110 wait_queue_head_t data_ready_queue
;
112 enum asahi_compass_chipset chipset
;
115 static const int ak8975_index_to_reg
[] = {
116 AK8975_REG_HXL
, AK8975_REG_HYL
, AK8975_REG_HZL
,
120 * Helper function to write to the I2C device's registers.
122 static int ak8975_write_data(struct i2c_client
*client
,
123 u8 reg
, u8 val
, u8 mask
, u8 shift
)
125 struct iio_dev
*indio_dev
= i2c_get_clientdata(client
);
126 struct ak8975_data
*data
= iio_priv(indio_dev
);
130 regval
= (data
->reg_cache
[reg
] & ~mask
) | (val
<< shift
);
131 ret
= i2c_smbus_write_byte_data(client
, reg
, regval
);
133 dev_err(&client
->dev
, "Write to device fails status %x\n", ret
);
136 data
->reg_cache
[reg
] = regval
;
142 * Handle data ready irq
144 static irqreturn_t
ak8975_irq_handler(int irq
, void *data
)
146 struct ak8975_data
*ak8975
= data
;
148 set_bit(0, &ak8975
->flags
);
149 wake_up(&ak8975
->data_ready_queue
);
155 * Install data ready interrupt handler
157 static int ak8975_setup_irq(struct ak8975_data
*data
)
159 struct i2c_client
*client
= data
->client
;
166 irq
= gpio_to_irq(data
->eoc_gpio
);
168 rc
= request_irq(irq
, ak8975_irq_handler
,
169 IRQF_TRIGGER_RISING
| IRQF_ONESHOT
,
170 dev_name(&client
->dev
), data
);
172 dev_err(&client
->dev
,
173 "irq %d request failed, (gpio %d): %d\n",
174 irq
, data
->eoc_gpio
, rc
);
178 init_waitqueue_head(&data
->data_ready_queue
);
179 clear_bit(0, &data
->flags
);
187 * Perform some start-of-day setup, including reading the asa calibration
188 * values and caching them.
190 static int ak8975_setup(struct i2c_client
*client
)
192 struct iio_dev
*indio_dev
= i2c_get_clientdata(client
);
193 struct ak8975_data
*data
= iio_priv(indio_dev
);
197 /* Confirm that the device we're talking to is really an AK8975. */
198 ret
= i2c_smbus_read_byte_data(client
, AK8975_REG_WIA
);
200 dev_err(&client
->dev
, "Error reading WIA\n");
204 if (device_id
!= AK8975_DEVICE_ID
) {
205 dev_err(&client
->dev
, "Device ak8975 not found\n");
209 /* Write the fused rom access mode. */
210 ret
= ak8975_write_data(client
,
212 AK8975_REG_CNTL_MODE_FUSE_ROM
,
213 AK8975_REG_CNTL_MODE_MASK
,
214 AK8975_REG_CNTL_MODE_SHIFT
);
216 dev_err(&client
->dev
, "Error in setting fuse access mode\n");
220 /* Get asa data and store in the device data. */
221 ret
= i2c_smbus_read_i2c_block_data(client
, AK8975_REG_ASAX
,
224 dev_err(&client
->dev
, "Not able to read asa data\n");
228 /* After reading fuse ROM data set power-down mode */
229 ret
= ak8975_write_data(client
,
231 AK8975_REG_CNTL_MODE_POWER_DOWN
,
232 AK8975_REG_CNTL_MODE_MASK
,
233 AK8975_REG_CNTL_MODE_SHIFT
);
235 if (data
->eoc_gpio
> 0 || client
->irq
) {
236 ret
= ak8975_setup_irq(data
);
238 dev_err(&client
->dev
,
239 "Error setting data ready interrupt\n");
245 dev_err(&client
->dev
, "Error in setting power-down mode\n");
250 * Precalculate scale factor (in Gauss units) for each axis and
251 * store in the device data.
253 * This scale factor is axis-dependent, and is derived from 3 calibration
254 * factors ASA(x), ASA(y), and ASA(z).
256 * These ASA values are read from the sensor device at start of day, and
257 * cached in the device context struct.
259 * Adjusting the flux value with the sensitivity adjustment value should be
260 * done via the following formula:
262 * Hadj = H * ( ( ( (ASA-128)*0.5 ) / 128 ) + 1 )
264 * where H is the raw value, ASA is the sensitivity adjustment, and Hadj
265 * is the resultant adjusted value.
267 * We reduce the formula to:
269 * Hadj = H * (ASA + 128) / 256
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:
274 * HuT = H * 1229/4096, or roughly, 3/10.
276 * Since 1uT = 0.01 gauss, our final scale factor becomes:
278 * Hadj = H * ((ASA + 128) / 256) * 3/10 * 1/100
279 * Hadj = H * ((ASA + 128) * 0.003) / 256
281 * Since ASA doesn't change, we cache the resultant scale factor into the
282 * device context in ak8975_setup().
284 if (data
->chipset
== AK8963
) {
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.
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]);
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]);
303 static int wait_conversion_complete_gpio(struct ak8975_data
*data
)
305 struct i2c_client
*client
= data
->client
;
306 u32 timeout_ms
= AK8975_MAX_CONVERSION_TIMEOUT
;
309 /* Wait for the conversion to complete. */
311 msleep(AK8975_CONVERSION_DONE_POLL_TIME
);
312 if (gpio_get_value(data
->eoc_gpio
))
314 timeout_ms
-= AK8975_CONVERSION_DONE_POLL_TIME
;
317 dev_err(&client
->dev
, "Conversion timeout happened\n");
321 ret
= i2c_smbus_read_byte_data(client
, AK8975_REG_ST1
);
323 dev_err(&client
->dev
, "Error in reading ST1\n");
328 static int wait_conversion_complete_polled(struct ak8975_data
*data
)
330 struct i2c_client
*client
= data
->client
;
332 u32 timeout_ms
= AK8975_MAX_CONVERSION_TIMEOUT
;
335 /* Wait for the conversion to complete. */
337 msleep(AK8975_CONVERSION_DONE_POLL_TIME
);
338 ret
= i2c_smbus_read_byte_data(client
, AK8975_REG_ST1
);
340 dev_err(&client
->dev
, "Error in reading ST1\n");
346 timeout_ms
-= AK8975_CONVERSION_DONE_POLL_TIME
;
349 dev_err(&client
->dev
, "Conversion timeout happened\n");
356 /* Returns 0 if the end of conversion interrupt occured or -ETIME otherwise */
357 static int wait_conversion_complete_interrupt(struct ak8975_data
*data
)
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
);
366 return ret
> 0 ? 0 : -ETIME
;
370 * Emits the raw flux value for the x, y, or z axis.
372 static int ak8975_read_axis(struct iio_dev
*indio_dev
, int index
, int *val
)
374 struct ak8975_data
*data
= iio_priv(indio_dev
);
375 struct i2c_client
*client
= data
->client
;
380 mutex_lock(&data
->lock
);
382 /* Set up the device for taking a sample. */
383 ret
= ak8975_write_data(client
,
385 AK8975_REG_CNTL_MODE_ONCE
,
386 AK8975_REG_CNTL_MODE_MASK
,
387 AK8975_REG_CNTL_MODE_SHIFT
);
389 dev_err(&client
->dev
, "Error in setting operating mode\n");
393 /* Wait for the conversion to complete. */
395 ret
= wait_conversion_complete_interrupt(data
);
396 else if (gpio_is_valid(data
->eoc_gpio
))
397 ret
= wait_conversion_complete_gpio(data
);
399 ret
= wait_conversion_complete_polled(data
);
403 /* This will be executed only for non-interrupt based waiting case */
404 if (ret
& AK8975_REG_ST1_DRDY_MASK
) {
405 ret
= i2c_smbus_read_byte_data(client
, AK8975_REG_ST2
);
407 dev_err(&client
->dev
, "Error in reading ST2\n");
410 if (ret
& (AK8975_REG_ST2_DERR_MASK
|
411 AK8975_REG_ST2_HOFL_MASK
)) {
412 dev_err(&client
->dev
, "ST2 status error 0x%x\n", ret
);
418 /* Read the flux value from the appropriate register
419 (the register is specified in the iio device attributes). */
420 ret
= i2c_smbus_read_word_data(client
, ak8975_index_to_reg
[index
]);
422 dev_err(&client
->dev
, "Read axis data fails\n");
427 mutex_unlock(&data
->lock
);
429 /* Endian conversion of the measured values. */
430 raw
= (s16
) (le16_to_cpu(meas_reg
));
432 /* Clamp to valid range. */
433 raw
= clamp_t(s16
, raw
, -4096, 4095);
438 mutex_unlock(&data
->lock
);
442 static int ak8975_read_raw(struct iio_dev
*indio_dev
,
443 struct iio_chan_spec
const *chan
,
447 struct ak8975_data
*data
= iio_priv(indio_dev
);
450 case IIO_CHAN_INFO_RAW
:
451 return ak8975_read_axis(indio_dev
, chan
->address
, val
);
452 case IIO_CHAN_INFO_SCALE
:
454 *val2
= data
->raw_to_gauss
[chan
->address
];
455 return IIO_VAL_INT_PLUS_MICRO
;
460 #define AK8975_CHANNEL(axis, index) \
464 .channel2 = IIO_MOD_##axis, \
465 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \
466 BIT(IIO_CHAN_INFO_SCALE), \
470 static const struct iio_chan_spec ak8975_channels
[] = {
471 AK8975_CHANNEL(X
, 0), AK8975_CHANNEL(Y
, 1), AK8975_CHANNEL(Z
, 2),
474 static const struct iio_info ak8975_info
= {
475 .read_raw
= &ak8975_read_raw
,
476 .driver_module
= THIS_MODULE
,
479 static const struct acpi_device_id ak_acpi_match
[] = {
482 {"INVN6500", AK8963
},
485 MODULE_DEVICE_TABLE(acpi
, ak_acpi_match
);
487 static char *ak8975_match_acpi_device(struct device
*dev
,
488 enum asahi_compass_chipset
*chipset
)
490 const struct acpi_device_id
*id
;
492 id
= acpi_match_device(dev
->driver
->acpi_match_table
, dev
);
495 *chipset
= (int)id
->driver_data
;
497 return (char *)dev_name(dev
);
500 static int ak8975_probe(struct i2c_client
*client
,
501 const struct i2c_device_id
*id
)
503 struct ak8975_data
*data
;
504 struct iio_dev
*indio_dev
;
509 /* Grab and set up the supplied GPIO. */
510 if (client
->dev
.platform_data
)
511 eoc_gpio
= *(int *)(client
->dev
.platform_data
);
512 else if (client
->dev
.of_node
)
513 eoc_gpio
= of_get_gpio(client
->dev
.of_node
, 0);
517 if (eoc_gpio
== -EPROBE_DEFER
)
518 return -EPROBE_DEFER
;
520 /* We may not have a GPIO based IRQ to scan, that is fine, we will
522 if (gpio_is_valid(eoc_gpio
)) {
523 err
= gpio_request_one(eoc_gpio
, GPIOF_IN
, "ak_8975");
525 dev_err(&client
->dev
,
526 "failed to request GPIO %d, error %d\n",
532 /* Register with IIO */
533 indio_dev
= iio_device_alloc(sizeof(*data
));
534 if (indio_dev
== NULL
) {
538 data
= iio_priv(indio_dev
);
539 i2c_set_clientdata(client
, indio_dev
);
541 data
->client
= client
;
542 data
->eoc_gpio
= eoc_gpio
;
545 /* id will be NULL when enumerated via ACPI */
548 (enum asahi_compass_chipset
)(id
->driver_data
);
549 name
= (char *) id
->name
;
550 } else if (ACPI_HANDLE(&client
->dev
))
551 name
= ak8975_match_acpi_device(&client
->dev
, &data
->chipset
);
556 dev_dbg(&client
->dev
, "Asahi compass chip %s\n", name
);
558 /* Perform some basic start-of-day setup of the device. */
559 err
= ak8975_setup(client
);
561 dev_err(&client
->dev
, "AK8975 initialization fails\n");
565 data
->client
= client
;
566 mutex_init(&data
->lock
);
567 data
->eoc_gpio
= eoc_gpio
;
568 indio_dev
->dev
.parent
= &client
->dev
;
569 indio_dev
->channels
= ak8975_channels
;
570 indio_dev
->num_channels
= ARRAY_SIZE(ak8975_channels
);
571 indio_dev
->info
= &ak8975_info
;
572 indio_dev
->name
= id
->name
;
573 indio_dev
->modes
= INDIO_DIRECT_MODE
;
574 indio_dev
->name
= name
;
575 err
= iio_device_register(indio_dev
);
582 iio_device_free(indio_dev
);
584 free_irq(data
->eoc_irq
, data
);
586 if (gpio_is_valid(eoc_gpio
))
592 static int ak8975_remove(struct i2c_client
*client
)
594 struct iio_dev
*indio_dev
= i2c_get_clientdata(client
);
595 struct ak8975_data
*data
= iio_priv(indio_dev
);
597 iio_device_unregister(indio_dev
);
600 free_irq(data
->eoc_irq
, data
);
602 if (gpio_is_valid(data
->eoc_gpio
))
603 gpio_free(data
->eoc_gpio
);
605 iio_device_free(indio_dev
);
610 static const struct i2c_device_id ak8975_id
[] = {
616 MODULE_DEVICE_TABLE(i2c
, ak8975_id
);
618 static const struct of_device_id ak8975_of_match
[] = {
619 { .compatible
= "asahi-kasei,ak8975", },
620 { .compatible
= "ak8975", },
623 MODULE_DEVICE_TABLE(of
, ak8975_of_match
);
625 static struct i2c_driver ak8975_driver
= {
628 .of_match_table
= ak8975_of_match
,
629 .acpi_match_table
= ACPI_PTR(ak_acpi_match
),
631 .probe
= ak8975_probe
,
632 .remove
= ak8975_remove
,
633 .id_table
= ak8975_id
,
635 module_i2c_driver(ak8975_driver
);
637 MODULE_AUTHOR("Laxman Dewangan <ldewangan@nvidia.com>");
638 MODULE_DESCRIPTION("AK8975 magnetometer driver");
639 MODULE_LICENSE("GPL");