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Linux/drivers/iio/magnetometer/ak8975.c

  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 #include <linux/acpi.h>
 35 #include <linux/regulator/consumer.h>
 36 
 37 #include <linux/iio/iio.h>
 38 #include <linux/iio/sysfs.h>
 39 #include <linux/iio/buffer.h>
 40 #include <linux/iio/trigger.h>
 41 #include <linux/iio/trigger_consumer.h>
 42 #include <linux/iio/triggered_buffer.h>
 43 
 44 #include <linux/iio/magnetometer/ak8975.h>
 45 
 46 /*
 47  * Register definitions, as well as various shifts and masks to get at the
 48  * individual fields of the registers.
 49  */
 50 #define AK8975_REG_WIA                  0x00
 51 #define AK8975_DEVICE_ID                0x48
 52 
 53 #define AK8975_REG_INFO                 0x01
 54 
 55 #define AK8975_REG_ST1                  0x02
 56 #define AK8975_REG_ST1_DRDY_SHIFT       0
 57 #define AK8975_REG_ST1_DRDY_MASK        (1 << AK8975_REG_ST1_DRDY_SHIFT)
 58 
 59 #define AK8975_REG_HXL                  0x03
 60 #define AK8975_REG_HXH                  0x04
 61 #define AK8975_REG_HYL                  0x05
 62 #define AK8975_REG_HYH                  0x06
 63 #define AK8975_REG_HZL                  0x07
 64 #define AK8975_REG_HZH                  0x08
 65 #define AK8975_REG_ST2                  0x09
 66 #define AK8975_REG_ST2_DERR_SHIFT       2
 67 #define AK8975_REG_ST2_DERR_MASK        (1 << AK8975_REG_ST2_DERR_SHIFT)
 68 
 69 #define AK8975_REG_ST2_HOFL_SHIFT       3
 70 #define AK8975_REG_ST2_HOFL_MASK        (1 << AK8975_REG_ST2_HOFL_SHIFT)
 71 
 72 #define AK8975_REG_CNTL                 0x0A
 73 #define AK8975_REG_CNTL_MODE_SHIFT      0
 74 #define AK8975_REG_CNTL_MODE_MASK       (0xF << AK8975_REG_CNTL_MODE_SHIFT)
 75 #define AK8975_REG_CNTL_MODE_POWER_DOWN 0x00
 76 #define AK8975_REG_CNTL_MODE_ONCE       0x01
 77 #define AK8975_REG_CNTL_MODE_SELF_TEST  0x08
 78 #define AK8975_REG_CNTL_MODE_FUSE_ROM   0x0F
 79 
 80 #define AK8975_REG_RSVC                 0x0B
 81 #define AK8975_REG_ASTC                 0x0C
 82 #define AK8975_REG_TS1                  0x0D
 83 #define AK8975_REG_TS2                  0x0E
 84 #define AK8975_REG_I2CDIS               0x0F
 85 #define AK8975_REG_ASAX                 0x10
 86 #define AK8975_REG_ASAY                 0x11
 87 #define AK8975_REG_ASAZ                 0x12
 88 
 89 #define AK8975_MAX_REGS                 AK8975_REG_ASAZ
 90 
 91 /*
 92  * AK09912 Register definitions
 93  */
 94 #define AK09912_REG_WIA1                0x00
 95 #define AK09912_REG_WIA2                0x01
 96 #define AK09912_DEVICE_ID               0x04
 97 #define AK09911_DEVICE_ID               0x05
 98 
 99 #define AK09911_REG_INFO1               0x02
100 #define AK09911_REG_INFO2               0x03
101 
102 #define AK09912_REG_ST1                 0x10
103 
104 #define AK09912_REG_ST1_DRDY_SHIFT      0
105 #define AK09912_REG_ST1_DRDY_MASK       (1 << AK09912_REG_ST1_DRDY_SHIFT)
106 
107 #define AK09912_REG_HXL                 0x11
108 #define AK09912_REG_HXH                 0x12
109 #define AK09912_REG_HYL                 0x13
110 #define AK09912_REG_HYH                 0x14
111 #define AK09912_REG_HZL                 0x15
112 #define AK09912_REG_HZH                 0x16
113 #define AK09912_REG_TMPS                0x17
114 
115 #define AK09912_REG_ST2                 0x18
116 #define AK09912_REG_ST2_HOFL_SHIFT      3
117 #define AK09912_REG_ST2_HOFL_MASK       (1 << AK09912_REG_ST2_HOFL_SHIFT)
118 
119 #define AK09912_REG_CNTL1               0x30
120 
121 #define AK09912_REG_CNTL2               0x31
122 #define AK09912_REG_CNTL_MODE_POWER_DOWN        0x00
123 #define AK09912_REG_CNTL_MODE_ONCE      0x01
124 #define AK09912_REG_CNTL_MODE_SELF_TEST 0x10
125 #define AK09912_REG_CNTL_MODE_FUSE_ROM  0x1F
126 #define AK09912_REG_CNTL2_MODE_SHIFT    0
127 #define AK09912_REG_CNTL2_MODE_MASK     (0x1F << AK09912_REG_CNTL2_MODE_SHIFT)
128 
129 #define AK09912_REG_CNTL3               0x32
130 
131 #define AK09912_REG_TS1                 0x33
132 #define AK09912_REG_TS2                 0x34
133 #define AK09912_REG_TS3                 0x35
134 #define AK09912_REG_I2CDIS              0x36
135 #define AK09912_REG_TS4                 0x37
136 
137 #define AK09912_REG_ASAX                0x60
138 #define AK09912_REG_ASAY                0x61
139 #define AK09912_REG_ASAZ                0x62
140 
141 #define AK09912_MAX_REGS                AK09912_REG_ASAZ
142 
143 /*
144  * Miscellaneous values.
145  */
146 #define AK8975_MAX_CONVERSION_TIMEOUT   500
147 #define AK8975_CONVERSION_DONE_POLL_TIME 10
148 #define AK8975_DATA_READY_TIMEOUT       ((100*HZ)/1000)
149 
150 /*
151  * Precalculate scale factor (in Gauss units) for each axis and
152  * store in the device data.
153  *
154  * This scale factor is axis-dependent, and is derived from 3 calibration
155  * factors ASA(x), ASA(y), and ASA(z).
156  *
157  * These ASA values are read from the sensor device at start of day, and
158  * cached in the device context struct.
159  *
160  * Adjusting the flux value with the sensitivity adjustment value should be
161  * done via the following formula:
162  *
163  * Hadj = H * ( ( ( (ASA-128)*0.5 ) / 128 ) + 1 )
164  * where H is the raw value, ASA is the sensitivity adjustment, and Hadj
165  * is the resultant adjusted value.
166  *
167  * We reduce the formula to:
168  *
169  * Hadj = H * (ASA + 128) / 256
170  *
171  * H is in the range of -4096 to 4095.  The magnetometer has a range of
172  * +-1229uT.  To go from the raw value to uT is:
173  *
174  * HuT = H * 1229/4096, or roughly, 3/10.
175  *
176  * Since 1uT = 0.01 gauss, our final scale factor becomes:
177  *
178  * Hadj = H * ((ASA + 128) / 256) * 3/10 * 1/100
179  * Hadj = H * ((ASA + 128) * 0.003) / 256
180  *
181  * Since ASA doesn't change, we cache the resultant scale factor into the
182  * device context in ak8975_setup().
183  *
184  * Given we use IIO_VAL_INT_PLUS_MICRO bit when displaying the scale, we
185  * multiply the stored scale value by 1e6.
186  */
187 static long ak8975_raw_to_gauss(u16 data)
188 {
189         return (((long)data + 128) * 3000) / 256;
190 }
191 
192 /*
193  * For AK8963 and AK09911, same calculation, but the device is less sensitive:
194  *
195  * H is in the range of +-8190.  The magnetometer has a range of
196  * +-4912uT.  To go from the raw value to uT is:
197  *
198  * HuT = H * 4912/8190, or roughly, 6/10, instead of 3/10.
199  */
200 
201 static long ak8963_09911_raw_to_gauss(u16 data)
202 {
203         return (((long)data + 128) * 6000) / 256;
204 }
205 
206 /*
207  * For AK09912, same calculation, except the device is more sensitive:
208  *
209  * H is in the range of -32752 to 32752.  The magnetometer has a range of
210  * +-4912uT.  To go from the raw value to uT is:
211  *
212  * HuT = H * 4912/32752, or roughly, 3/20, instead of 3/10.
213  */
214 static long ak09912_raw_to_gauss(u16 data)
215 {
216         return (((long)data + 128) * 1500) / 256;
217 }
218 
219 /* Compatible Asahi Kasei Compass parts */
220 enum asahi_compass_chipset {
221         AK8975,
222         AK8963,
223         AK09911,
224         AK09912,
225         AK_MAX_TYPE
226 };
227 
228 enum ak_ctrl_reg_addr {
229         ST1,
230         ST2,
231         CNTL,
232         ASA_BASE,
233         MAX_REGS,
234         REGS_END,
235 };
236 
237 enum ak_ctrl_reg_mask {
238         ST1_DRDY,
239         ST2_HOFL,
240         ST2_DERR,
241         CNTL_MODE,
242         MASK_END,
243 };
244 
245 enum ak_ctrl_mode {
246         POWER_DOWN,
247         MODE_ONCE,
248         SELF_TEST,
249         FUSE_ROM,
250         MODE_END,
251 };
252 
253 struct ak_def {
254         enum asahi_compass_chipset type;
255         long (*raw_to_gauss)(u16 data);
256         u16 range;
257         u8 ctrl_regs[REGS_END];
258         u8 ctrl_masks[MASK_END];
259         u8 ctrl_modes[MODE_END];
260         u8 data_regs[3];
261 };
262 
263 static const struct ak_def ak_def_array[AK_MAX_TYPE] = {
264         {
265                 .type = AK8975,
266                 .raw_to_gauss = ak8975_raw_to_gauss,
267                 .range = 4096,
268                 .ctrl_regs = {
269                         AK8975_REG_ST1,
270                         AK8975_REG_ST2,
271                         AK8975_REG_CNTL,
272                         AK8975_REG_ASAX,
273                         AK8975_MAX_REGS},
274                 .ctrl_masks = {
275                         AK8975_REG_ST1_DRDY_MASK,
276                         AK8975_REG_ST2_HOFL_MASK,
277                         AK8975_REG_ST2_DERR_MASK,
278                         AK8975_REG_CNTL_MODE_MASK},
279                 .ctrl_modes = {
280                         AK8975_REG_CNTL_MODE_POWER_DOWN,
281                         AK8975_REG_CNTL_MODE_ONCE,
282                         AK8975_REG_CNTL_MODE_SELF_TEST,
283                         AK8975_REG_CNTL_MODE_FUSE_ROM},
284                 .data_regs = {
285                         AK8975_REG_HXL,
286                         AK8975_REG_HYL,
287                         AK8975_REG_HZL},
288         },
289         {
290                 .type = AK8963,
291                 .raw_to_gauss = ak8963_09911_raw_to_gauss,
292                 .range = 8190,
293                 .ctrl_regs = {
294                         AK8975_REG_ST1,
295                         AK8975_REG_ST2,
296                         AK8975_REG_CNTL,
297                         AK8975_REG_ASAX,
298                         AK8975_MAX_REGS},
299                 .ctrl_masks = {
300                         AK8975_REG_ST1_DRDY_MASK,
301                         AK8975_REG_ST2_HOFL_MASK,
302                         0,
303                         AK8975_REG_CNTL_MODE_MASK},
304                 .ctrl_modes = {
305                         AK8975_REG_CNTL_MODE_POWER_DOWN,
306                         AK8975_REG_CNTL_MODE_ONCE,
307                         AK8975_REG_CNTL_MODE_SELF_TEST,
308                         AK8975_REG_CNTL_MODE_FUSE_ROM},
309                 .data_regs = {
310                         AK8975_REG_HXL,
311                         AK8975_REG_HYL,
312                         AK8975_REG_HZL},
313         },
314         {
315                 .type = AK09911,
316                 .raw_to_gauss = ak8963_09911_raw_to_gauss,
317                 .range = 8192,
318                 .ctrl_regs = {
319                         AK09912_REG_ST1,
320                         AK09912_REG_ST2,
321                         AK09912_REG_CNTL2,
322                         AK09912_REG_ASAX,
323                         AK09912_MAX_REGS},
324                 .ctrl_masks = {
325                         AK09912_REG_ST1_DRDY_MASK,
326                         AK09912_REG_ST2_HOFL_MASK,
327                         0,
328                         AK09912_REG_CNTL2_MODE_MASK},
329                 .ctrl_modes = {
330                         AK09912_REG_CNTL_MODE_POWER_DOWN,
331                         AK09912_REG_CNTL_MODE_ONCE,
332                         AK09912_REG_CNTL_MODE_SELF_TEST,
333                         AK09912_REG_CNTL_MODE_FUSE_ROM},
334                 .data_regs = {
335                         AK09912_REG_HXL,
336                         AK09912_REG_HYL,
337                         AK09912_REG_HZL},
338         },
339         {
340                 .type = AK09912,
341                 .raw_to_gauss = ak09912_raw_to_gauss,
342                 .range = 32752,
343                 .ctrl_regs = {
344                         AK09912_REG_ST1,
345                         AK09912_REG_ST2,
346                         AK09912_REG_CNTL2,
347                         AK09912_REG_ASAX,
348                         AK09912_MAX_REGS},
349                 .ctrl_masks = {
350                         AK09912_REG_ST1_DRDY_MASK,
351                         AK09912_REG_ST2_HOFL_MASK,
352                         0,
353                         AK09912_REG_CNTL2_MODE_MASK},
354                 .ctrl_modes = {
355                         AK09912_REG_CNTL_MODE_POWER_DOWN,
356                         AK09912_REG_CNTL_MODE_ONCE,
357                         AK09912_REG_CNTL_MODE_SELF_TEST,
358                         AK09912_REG_CNTL_MODE_FUSE_ROM},
359                 .data_regs = {
360                         AK09912_REG_HXL,
361                         AK09912_REG_HYL,
362                         AK09912_REG_HZL},
363         }
364 };
365 
366 /*
367  * Per-instance context data for the device.
368  */
369 struct ak8975_data {
370         struct i2c_client       *client;
371         const struct ak_def     *def;
372         struct mutex            lock;
373         u8                      asa[3];
374         long                    raw_to_gauss[3];
375         int                     eoc_gpio;
376         int                     eoc_irq;
377         wait_queue_head_t       data_ready_queue;
378         unsigned long           flags;
379         u8                      cntl_cache;
380         struct iio_mount_matrix orientation;
381         struct regulator        *vdd;
382 };
383 
384 /* Enable attached power regulator if any. */
385 static int ak8975_power_on(struct i2c_client *client)
386 {
387         const struct iio_dev *indio_dev = i2c_get_clientdata(client);
388         struct ak8975_data *data = iio_priv(indio_dev);
389         int ret;
390 
391         data->vdd = devm_regulator_get(&client->dev, "vdd");
392         if (IS_ERR_OR_NULL(data->vdd)) {
393                 ret = PTR_ERR(data->vdd);
394                 if (ret == -ENODEV)
395                         ret = 0;
396         } else {
397                 ret = regulator_enable(data->vdd);
398         }
399 
400         if (ret)
401                 dev_err(&client->dev, "failed to enable Vdd supply: %d\n", ret);
402         return ret;
403 }
404 
405 /* Disable attached power regulator if any. */
406 static void ak8975_power_off(const struct i2c_client *client)
407 {
408         const struct iio_dev *indio_dev = i2c_get_clientdata(client);
409         const struct ak8975_data *data = iio_priv(indio_dev);
410 
411         if (!IS_ERR_OR_NULL(data->vdd))
412                 regulator_disable(data->vdd);
413 }
414 
415 /*
416  * Return 0 if the i2c device is the one we expect.
417  * return a negative error number otherwise
418  */
419 static int ak8975_who_i_am(struct i2c_client *client,
420                            enum asahi_compass_chipset type)
421 {
422         u8 wia_val[2];
423         int ret;
424 
425         /*
426          * Signature for each device:
427          * Device   |  WIA1      |  WIA2
428          * AK09912  |  DEVICE_ID |  AK09912_DEVICE_ID
429          * AK09911  |  DEVICE_ID |  AK09911_DEVICE_ID
430          * AK8975   |  DEVICE_ID |  NA
431          * AK8963   |  DEVICE_ID |  NA
432          */
433         ret = i2c_smbus_read_i2c_block_data(client, AK09912_REG_WIA1,
434                                             2, wia_val);
435         if (ret < 0) {
436                 dev_err(&client->dev, "Error reading WIA\n");
437                 return ret;
438         }
439 
440         if (wia_val[0] != AK8975_DEVICE_ID)
441                 return -ENODEV;
442 
443         switch (type) {
444         case AK8975:
445         case AK8963:
446                 return 0;
447         case AK09911:
448                 if (wia_val[1] == AK09911_DEVICE_ID)
449                         return 0;
450                 break;
451         case AK09912:
452                 if (wia_val[1] == AK09912_DEVICE_ID)
453                         return 0;
454                 break;
455         default:
456                 dev_err(&client->dev, "Type %d unknown\n", type);
457         }
458         return -ENODEV;
459 }
460 
461 /*
462  * Helper function to write to CNTL register.
463  */
464 static int ak8975_set_mode(struct ak8975_data *data, enum ak_ctrl_mode mode)
465 {
466         u8 regval;
467         int ret;
468 
469         regval = (data->cntl_cache & ~data->def->ctrl_masks[CNTL_MODE]) |
470                  data->def->ctrl_modes[mode];
471         ret = i2c_smbus_write_byte_data(data->client,
472                                         data->def->ctrl_regs[CNTL], regval);
473         if (ret < 0) {
474                 return ret;
475         }
476         data->cntl_cache = regval;
477         /* After mode change wait atleast 100us */
478         usleep_range(100, 500);
479 
480         return 0;
481 }
482 
483 /*
484  * Handle data ready irq
485  */
486 static irqreturn_t ak8975_irq_handler(int irq, void *data)
487 {
488         struct ak8975_data *ak8975 = data;
489 
490         set_bit(0, &ak8975->flags);
491         wake_up(&ak8975->data_ready_queue);
492 
493         return IRQ_HANDLED;
494 }
495 
496 /*
497  * Install data ready interrupt handler
498  */
499 static int ak8975_setup_irq(struct ak8975_data *data)
500 {
501         struct i2c_client *client = data->client;
502         int rc;
503         int irq;
504 
505         init_waitqueue_head(&data->data_ready_queue);
506         clear_bit(0, &data->flags);
507         if (client->irq)
508                 irq = client->irq;
509         else
510                 irq = gpio_to_irq(data->eoc_gpio);
511 
512         rc = devm_request_irq(&client->dev, irq, ak8975_irq_handler,
513                               IRQF_TRIGGER_RISING | IRQF_ONESHOT,
514                               dev_name(&client->dev), data);
515         if (rc < 0) {
516                 dev_err(&client->dev,
517                         "irq %d request failed, (gpio %d): %d\n",
518                         irq, data->eoc_gpio, rc);
519                 return rc;
520         }
521 
522         data->eoc_irq = irq;
523 
524         return rc;
525 }
526 
527 
528 /*
529  * Perform some start-of-day setup, including reading the asa calibration
530  * values and caching them.
531  */
532 static int ak8975_setup(struct i2c_client *client)
533 {
534         struct iio_dev *indio_dev = i2c_get_clientdata(client);
535         struct ak8975_data *data = iio_priv(indio_dev);
536         int ret;
537 
538         /* Write the fused rom access mode. */
539         ret = ak8975_set_mode(data, FUSE_ROM);
540         if (ret < 0) {
541                 dev_err(&client->dev, "Error in setting fuse access mode\n");
542                 return ret;
543         }
544 
545         /* Get asa data and store in the device data. */
546         ret = i2c_smbus_read_i2c_block_data(client,
547                                             data->def->ctrl_regs[ASA_BASE],
548                                             3, data->asa);
549         if (ret < 0) {
550                 dev_err(&client->dev, "Not able to read asa data\n");
551                 return ret;
552         }
553 
554         /* After reading fuse ROM data set power-down mode */
555         ret = ak8975_set_mode(data, POWER_DOWN);
556         if (ret < 0) {
557                 dev_err(&client->dev, "Error in setting power-down mode\n");
558                 return ret;
559         }
560 
561         if (data->eoc_gpio > 0 || client->irq > 0) {
562                 ret = ak8975_setup_irq(data);
563                 if (ret < 0) {
564                         dev_err(&client->dev,
565                                 "Error setting data ready interrupt\n");
566                         return ret;
567                 }
568         }
569 
570         data->raw_to_gauss[0] = data->def->raw_to_gauss(data->asa[0]);
571         data->raw_to_gauss[1] = data->def->raw_to_gauss(data->asa[1]);
572         data->raw_to_gauss[2] = data->def->raw_to_gauss(data->asa[2]);
573 
574         return 0;
575 }
576 
577 static int wait_conversion_complete_gpio(struct ak8975_data *data)
578 {
579         struct i2c_client *client = data->client;
580         u32 timeout_ms = AK8975_MAX_CONVERSION_TIMEOUT;
581         int ret;
582 
583         /* Wait for the conversion to complete. */
584         while (timeout_ms) {
585                 msleep(AK8975_CONVERSION_DONE_POLL_TIME);
586                 if (gpio_get_value(data->eoc_gpio))
587                         break;
588                 timeout_ms -= AK8975_CONVERSION_DONE_POLL_TIME;
589         }
590         if (!timeout_ms) {
591                 dev_err(&client->dev, "Conversion timeout happened\n");
592                 return -EINVAL;
593         }
594 
595         ret = i2c_smbus_read_byte_data(client, data->def->ctrl_regs[ST1]);
596         if (ret < 0)
597                 dev_err(&client->dev, "Error in reading ST1\n");
598 
599         return ret;
600 }
601 
602 static int wait_conversion_complete_polled(struct ak8975_data *data)
603 {
604         struct i2c_client *client = data->client;
605         u8 read_status;
606         u32 timeout_ms = AK8975_MAX_CONVERSION_TIMEOUT;
607         int ret;
608 
609         /* Wait for the conversion to complete. */
610         while (timeout_ms) {
611                 msleep(AK8975_CONVERSION_DONE_POLL_TIME);
612                 ret = i2c_smbus_read_byte_data(client,
613                                                data->def->ctrl_regs[ST1]);
614                 if (ret < 0) {
615                         dev_err(&client->dev, "Error in reading ST1\n");
616                         return ret;
617                 }
618                 read_status = ret;
619                 if (read_status)
620                         break;
621                 timeout_ms -= AK8975_CONVERSION_DONE_POLL_TIME;
622         }
623         if (!timeout_ms) {
624                 dev_err(&client->dev, "Conversion timeout happened\n");
625                 return -EINVAL;
626         }
627 
628         return read_status;
629 }
630 
631 /* Returns 0 if the end of conversion interrupt occured or -ETIME otherwise */
632 static int wait_conversion_complete_interrupt(struct ak8975_data *data)
633 {
634         int ret;
635 
636         ret = wait_event_timeout(data->data_ready_queue,
637                                  test_bit(0, &data->flags),
638                                  AK8975_DATA_READY_TIMEOUT);
639         clear_bit(0, &data->flags);
640 
641         return ret > 0 ? 0 : -ETIME;
642 }
643 
644 static int ak8975_start_read_axis(struct ak8975_data *data,
645                                   const struct i2c_client *client)
646 {
647         /* Set up the device for taking a sample. */
648         int ret = ak8975_set_mode(data, MODE_ONCE);
649 
650         if (ret < 0) {
651                 dev_err(&client->dev, "Error in setting operating mode\n");
652                 return ret;
653         }
654 
655         /* Wait for the conversion to complete. */
656         if (data->eoc_irq)
657                 ret = wait_conversion_complete_interrupt(data);
658         else if (gpio_is_valid(data->eoc_gpio))
659                 ret = wait_conversion_complete_gpio(data);
660         else
661                 ret = wait_conversion_complete_polled(data);
662         if (ret < 0)
663                 return ret;
664 
665         /* This will be executed only for non-interrupt based waiting case */
666         if (ret & data->def->ctrl_masks[ST1_DRDY]) {
667                 ret = i2c_smbus_read_byte_data(client,
668                                                data->def->ctrl_regs[ST2]);
669                 if (ret < 0) {
670                         dev_err(&client->dev, "Error in reading ST2\n");
671                         return ret;
672                 }
673                 if (ret & (data->def->ctrl_masks[ST2_DERR] |
674                            data->def->ctrl_masks[ST2_HOFL])) {
675                         dev_err(&client->dev, "ST2 status error 0x%x\n", ret);
676                         return -EINVAL;
677                 }
678         }
679 
680         return 0;
681 }
682 
683 /* Retrieve raw flux value for one of the x, y, or z axis.  */
684 static int ak8975_read_axis(struct iio_dev *indio_dev, int index, int *val)
685 {
686         struct ak8975_data *data = iio_priv(indio_dev);
687         const struct i2c_client *client = data->client;
688         const struct ak_def *def = data->def;
689         int ret;
690 
691         mutex_lock(&data->lock);
692 
693         ret = ak8975_start_read_axis(data, client);
694         if (ret)
695                 goto exit;
696 
697         ret = i2c_smbus_read_word_data(client, def->data_regs[index]);
698         if (ret < 0)
699                 goto exit;
700 
701         mutex_unlock(&data->lock);
702 
703         /* Clamp to valid range. */
704         *val = clamp_t(s16, ret, -def->range, def->range);
705         return IIO_VAL_INT;
706 
707 exit:
708         mutex_unlock(&data->lock);
709         dev_err(&client->dev, "Error in reading axis\n");
710         return ret;
711 }
712 
713 static int ak8975_read_raw(struct iio_dev *indio_dev,
714                            struct iio_chan_spec const *chan,
715                            int *val, int *val2,
716                            long mask)
717 {
718         struct ak8975_data *data = iio_priv(indio_dev);
719 
720         switch (mask) {
721         case IIO_CHAN_INFO_RAW:
722                 return ak8975_read_axis(indio_dev, chan->address, val);
723         case IIO_CHAN_INFO_SCALE:
724                 *val = 0;
725                 *val2 = data->raw_to_gauss[chan->address];
726                 return IIO_VAL_INT_PLUS_MICRO;
727         }
728         return -EINVAL;
729 }
730 
731 static const struct iio_mount_matrix *
732 ak8975_get_mount_matrix(const struct iio_dev *indio_dev,
733                         const struct iio_chan_spec *chan)
734 {
735         return &((struct ak8975_data *)iio_priv(indio_dev))->orientation;
736 }
737 
738 static const struct iio_chan_spec_ext_info ak8975_ext_info[] = {
739         IIO_MOUNT_MATRIX(IIO_SHARED_BY_DIR, ak8975_get_mount_matrix),
740         { },
741 };
742 
743 #define AK8975_CHANNEL(axis, index)                                     \
744         {                                                               \
745                 .type = IIO_MAGN,                                       \
746                 .modified = 1,                                          \
747                 .channel2 = IIO_MOD_##axis,                             \
748                 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |          \
749                              BIT(IIO_CHAN_INFO_SCALE),                  \
750                 .address = index,                                       \
751                 .scan_index = index,                                    \
752                 .scan_type = {                                          \
753                         .sign = 's',                                    \
754                         .realbits = 16,                                 \
755                         .storagebits = 16,                              \
756                         .endianness = IIO_CPU                           \
757                 },                                                      \
758                 .ext_info = ak8975_ext_info,                            \
759         }
760 
761 static const struct iio_chan_spec ak8975_channels[] = {
762         AK8975_CHANNEL(X, 0), AK8975_CHANNEL(Y, 1), AK8975_CHANNEL(Z, 2),
763         IIO_CHAN_SOFT_TIMESTAMP(3),
764 };
765 
766 static const unsigned long ak8975_scan_masks[] = { 0x7, 0 };
767 
768 static const struct iio_info ak8975_info = {
769         .read_raw = &ak8975_read_raw,
770         .driver_module = THIS_MODULE,
771 };
772 
773 static const struct acpi_device_id ak_acpi_match[] = {
774         {"AK8975", AK8975},
775         {"AK8963", AK8963},
776         {"INVN6500", AK8963},
777         {"AK09911", AK09911},
778         {"AK09912", AK09912},
779         { },
780 };
781 MODULE_DEVICE_TABLE(acpi, ak_acpi_match);
782 
783 static const char *ak8975_match_acpi_device(struct device *dev,
784                                             enum asahi_compass_chipset *chipset)
785 {
786         const struct acpi_device_id *id;
787 
788         id = acpi_match_device(dev->driver->acpi_match_table, dev);
789         if (!id)
790                 return NULL;
791         *chipset = (int)id->driver_data;
792 
793         return dev_name(dev);
794 }
795 
796 static void ak8975_fill_buffer(struct iio_dev *indio_dev)
797 {
798         struct ak8975_data *data = iio_priv(indio_dev);
799         const struct i2c_client *client = data->client;
800         const struct ak_def *def = data->def;
801         int ret;
802         s16 buff[8]; /* 3 x 16 bits axis values + 1 aligned 64 bits timestamp */
803 
804         mutex_lock(&data->lock);
805 
806         ret = ak8975_start_read_axis(data, client);
807         if (ret)
808                 goto unlock;
809 
810         /*
811          * For each axis, read the flux value from the appropriate register
812          * (the register is specified in the iio device attributes).
813          */
814         ret = i2c_smbus_read_i2c_block_data_or_emulated(client,
815                                                         def->data_regs[0],
816                                                         3 * sizeof(buff[0]),
817                                                         (u8 *)buff);
818         if (ret < 0)
819                 goto unlock;
820 
821         mutex_unlock(&data->lock);
822 
823         /* Clamp to valid range. */
824         buff[0] = clamp_t(s16, le16_to_cpu(buff[0]), -def->range, def->range);
825         buff[1] = clamp_t(s16, le16_to_cpu(buff[1]), -def->range, def->range);
826         buff[2] = clamp_t(s16, le16_to_cpu(buff[2]), -def->range, def->range);
827 
828         iio_push_to_buffers_with_timestamp(indio_dev, buff, iio_get_time_ns());
829         return;
830 
831 unlock:
832         mutex_unlock(&data->lock);
833         dev_err(&client->dev, "Error in reading axes block\n");
834 }
835 
836 static irqreturn_t ak8975_handle_trigger(int irq, void *p)
837 {
838         const struct iio_poll_func *pf = p;
839         struct iio_dev *indio_dev = pf->indio_dev;
840 
841         ak8975_fill_buffer(indio_dev);
842         iio_trigger_notify_done(indio_dev->trig);
843         return IRQ_HANDLED;
844 }
845 
846 static int ak8975_probe(struct i2c_client *client,
847                         const struct i2c_device_id *id)
848 {
849         struct ak8975_data *data;
850         struct iio_dev *indio_dev;
851         int eoc_gpio;
852         int err;
853         const char *name = NULL;
854         enum asahi_compass_chipset chipset = AK_MAX_TYPE;
855         const struct ak8975_platform_data *pdata =
856                 dev_get_platdata(&client->dev);
857 
858         /* Grab and set up the supplied GPIO. */
859         if (pdata)
860                 eoc_gpio = pdata->eoc_gpio;
861         else if (client->dev.of_node)
862                 eoc_gpio = of_get_gpio(client->dev.of_node, 0);
863         else
864                 eoc_gpio = -1;
865 
866         if (eoc_gpio == -EPROBE_DEFER)
867                 return -EPROBE_DEFER;
868 
869         /* We may not have a GPIO based IRQ to scan, that is fine, we will
870            poll if so */
871         if (gpio_is_valid(eoc_gpio)) {
872                 err = devm_gpio_request_one(&client->dev, eoc_gpio,
873                                                         GPIOF_IN, "ak_8975");
874                 if (err < 0) {
875                         dev_err(&client->dev,
876                                 "failed to request GPIO %d, error %d\n",
877                                                         eoc_gpio, err);
878                         return err;
879                 }
880         }
881 
882         /* Register with IIO */
883         indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
884         if (indio_dev == NULL)
885                 return -ENOMEM;
886 
887         data = iio_priv(indio_dev);
888         i2c_set_clientdata(client, indio_dev);
889 
890         data->client = client;
891         data->eoc_gpio = eoc_gpio;
892         data->eoc_irq = 0;
893 
894         if (!pdata) {
895                 err = of_iio_read_mount_matrix(&client->dev,
896                                                "mount-matrix",
897                                                &data->orientation);
898                 if (err)
899                         return err;
900         } else
901                 data->orientation = pdata->orientation;
902 
903         /* id will be NULL when enumerated via ACPI */
904         if (id) {
905                 chipset = (enum asahi_compass_chipset)(id->driver_data);
906                 name = id->name;
907         } else if (ACPI_HANDLE(&client->dev)) {
908                 name = ak8975_match_acpi_device(&client->dev, &chipset);
909                 if (!name)
910                         return -ENODEV;
911         } else
912                 return -ENOSYS;
913 
914         if (chipset >= AK_MAX_TYPE) {
915                 dev_err(&client->dev, "AKM device type unsupported: %d\n",
916                         chipset);
917                 return -ENODEV;
918         }
919 
920         data->def = &ak_def_array[chipset];
921 
922         err = ak8975_power_on(client);
923         if (err)
924                 return err;
925 
926         err = ak8975_who_i_am(client, data->def->type);
927         if (err < 0) {
928                 dev_err(&client->dev, "Unexpected device\n");
929                 goto power_off;
930         }
931         dev_dbg(&client->dev, "Asahi compass chip %s\n", name);
932 
933         /* Perform some basic start-of-day setup of the device. */
934         err = ak8975_setup(client);
935         if (err < 0) {
936                 dev_err(&client->dev, "%s initialization fails\n", name);
937                 goto power_off;
938         }
939 
940         mutex_init(&data->lock);
941         indio_dev->dev.parent = &client->dev;
942         indio_dev->channels = ak8975_channels;
943         indio_dev->num_channels = ARRAY_SIZE(ak8975_channels);
944         indio_dev->info = &ak8975_info;
945         indio_dev->available_scan_masks = ak8975_scan_masks;
946         indio_dev->modes = INDIO_DIRECT_MODE;
947         indio_dev->name = name;
948 
949         err = iio_triggered_buffer_setup(indio_dev, NULL, ak8975_handle_trigger,
950                                          NULL);
951         if (err) {
952                 dev_err(&client->dev, "triggered buffer setup failed\n");
953                 goto power_off;
954         }
955 
956         err = iio_device_register(indio_dev);
957         if (err) {
958                 dev_err(&client->dev, "device register failed\n");
959                 goto cleanup_buffer;
960         }
961 
962         return 0;
963 
964 cleanup_buffer:
965         iio_triggered_buffer_cleanup(indio_dev);
966 power_off:
967         ak8975_power_off(client);
968         return err;
969 }
970 
971 static int ak8975_remove(struct i2c_client *client)
972 {
973         struct iio_dev *indio_dev = i2c_get_clientdata(client);
974 
975         iio_device_unregister(indio_dev);
976         iio_triggered_buffer_cleanup(indio_dev);
977         ak8975_power_off(client);
978 
979         return 0;
980 }
981 
982 static const struct i2c_device_id ak8975_id[] = {
983         {"ak8975", AK8975},
984         {"ak8963", AK8963},
985         {"AK8963", AK8963},
986         {"ak09911", AK09911},
987         {"ak09912", AK09912},
988         {}
989 };
990 
991 MODULE_DEVICE_TABLE(i2c, ak8975_id);
992 
993 static const struct of_device_id ak8975_of_match[] = {
994         { .compatible = "asahi-kasei,ak8975", },
995         { .compatible = "ak8975", },
996         { .compatible = "asahi-kasei,ak8963", },
997         { .compatible = "ak8963", },
998         { .compatible = "asahi-kasei,ak09911", },
999         { .compatible = "ak09911", },
1000         { .compatible = "asahi-kasei,ak09912", },
1001         { .compatible = "ak09912", },
1002         {}
1003 };
1004 MODULE_DEVICE_TABLE(of, ak8975_of_match);
1005 
1006 static struct i2c_driver ak8975_driver = {
1007         .driver = {
1008                 .name   = "ak8975",
1009                 .of_match_table = of_match_ptr(ak8975_of_match),
1010                 .acpi_match_table = ACPI_PTR(ak_acpi_match),
1011         },
1012         .probe          = ak8975_probe,
1013         .remove         = ak8975_remove,
1014         .id_table       = ak8975_id,
1015 };
1016 module_i2c_driver(ak8975_driver);
1017 
1018 MODULE_AUTHOR("Laxman Dewangan <ldewangan@nvidia.com>");
1019 MODULE_DESCRIPTION("AK8975 magnetometer driver");
1020 MODULE_LICENSE("GPL");
1021 

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