drivers/iio/proximity/as3935.c

   1 /*
   2  * as3935.c - Support for AS3935 Franklin lightning sensor
   3  *
   4  * Copyright (C) 2014 Matt Ranostay <mranostay@gmail.com>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  14  * GNU General Public License for more details.
  15  *
  16  */
  17
  18 #include <linux/module.h>
  19 #include <linux/init.h>
  20 #include <linux/interrupt.h>
  21 #include <linux/delay.h>
  22 #include <linux/workqueue.h>
  23 #include <linux/mutex.h>
  24 #include <linux/err.h>
  25 #include <linux/irq.h>
  26 #include <linux/gpio.h>
  27 #include <linux/spi/spi.h>
  28 #include <linux/iio/iio.h>
  29 #include <linux/iio/sysfs.h>
  30 #include <linux/iio/trigger.h>
  31 #include <linux/iio/trigger_consumer.h>
  32 #include <linux/iio/buffer.h>
  33 #include <linux/iio/triggered_buffer.h>
  34 #include <linux/of_gpio.h>
  35
  36
  37 #define AS3935_AFE_GAIN         0x00
  38 #define AS3935_AFE_MASK         0x3F
  39 #define AS3935_AFE_GAIN_MAX     0x1F
  40 #define AS3935_AFE_PWR_BIT      BIT(0)
  41
  42 #define AS3935_INT              0x03
  43 #define AS3935_INT_MASK         0x07
  44 #define AS3935_EVENT_INT        BIT(3)
  45 #define AS3935_NOISE_INT        BIT(1)
  46
  47 #define AS3935_DATA             0x07
  48 #define AS3935_DATA_MASK        0x3F
  49
  50 #define AS3935_TUNE_CAP         0x08
  51 #define AS3935_CALIBRATE        0x3D
  52
  53 #define AS3935_WRITE_DATA       BIT(15)
  54 #define AS3935_READ_DATA        BIT(14)
  55 #define AS3935_ADDRESS(x)       ((x) << 8)
  56
  57 #define MAX_PF_CAP              120
  58 #define TUNE_CAP_DIV            8
  59
  60 struct as3935_state {
  61         struct spi_device *spi;
  62         struct iio_trigger *trig;
  63         struct mutex lock;
  64         struct delayed_work work;
  65
  66         u32 tune_cap;
  67         u8 buffer[16]; /* 8-bit data + 56-bit padding + 64-bit timestamp */
  68         u8 buf[2] ____cacheline_aligned;
  69 };
  70
  71 static const struct iio_chan_spec as3935_channels[] = {
  72         {
  73                 .type           = IIO_PROXIMITY,
  74                 .info_mask_separate =
  75                         BIT(IIO_CHAN_INFO_RAW) |
  76                         BIT(IIO_CHAN_INFO_PROCESSED) |
  77                         BIT(IIO_CHAN_INFO_SCALE),
  78                 .scan_index     = 0,
  79                 .scan_type = {
  80                         .sign           = 'u',
  81                         .realbits       = 6,
  82                         .storagebits    = 8,
  83                 },
  84         },
  85         IIO_CHAN_SOFT_TIMESTAMP(1),
  86 };
  87
  88 static int as3935_read(struct as3935_state *st, unsigned int reg, int *val)
  89 {
  90         u8 cmd;
  91         int ret;
  92
  93         cmd = (AS3935_READ_DATA | AS3935_ADDRESS(reg)) >> 8;
  94         ret = spi_w8r8(st->spi, cmd);
  95         if (ret < 0)
  96                 return ret;
  97         *val = ret;
  98
  99         return 0;
 100 }
 101
 102 static int as3935_write(struct as3935_state *st,
 103                                 unsigned int reg,
 104                                 unsigned int val)
 105 {
 106         u8 *buf = st->buf;
 107
 108         buf[0] = (AS3935_WRITE_DATA | AS3935_ADDRESS(reg)) >> 8;
 109         buf[1] = val;
 110
 111         return spi_write(st->spi, buf, 2);
 112 }
 113
 114 static ssize_t as3935_sensor_sensitivity_show(struct device *dev,
 115                                         struct device_attribute *attr,
 116                                         char *buf)
 117 {
 118         struct as3935_state *st = iio_priv(dev_to_iio_dev(dev));
 119         int val, ret;
 120
 121         ret = as3935_read(st, AS3935_AFE_GAIN, &val);
 122         if (ret)
 123                 return ret;
 124         val = (val & AS3935_AFE_MASK) >> 1;
 125
 126         return sprintf(buf, "%d\n", val);
 127 }
 128
 129 static ssize_t as3935_sensor_sensitivity_store(struct device *dev,
 130                                         struct device_attribute *attr,
 131                                         const char *buf, size_t len)
 132 {
 133         struct as3935_state *st = iio_priv(dev_to_iio_dev(dev));
 134         unsigned long val;
 135         int ret;
 136
 137         ret = kstrtoul((const char *) buf, 10, &val);
 138         if (ret)
 139                 return -EINVAL;
 140
 141         if (val > AS3935_AFE_GAIN_MAX)
 142                 return -EINVAL;
 143
 144         as3935_write(st, AS3935_AFE_GAIN, val << 1);
 145
 146         return len;
 147 }
 148
 149 static IIO_DEVICE_ATTR(sensor_sensitivity, S_IRUGO | S_IWUSR,
 150         as3935_sensor_sensitivity_show, as3935_sensor_sensitivity_store, 0);
 151
 152
 153 static struct attribute *as3935_attributes[] = {
 154         &iio_dev_attr_sensor_sensitivity.dev_attr.attr,
 155         NULL,
 156 };
 157
 158 static struct attribute_group as3935_attribute_group = {
 159         .attrs = as3935_attributes,
 160 };
 161
 162 static int as3935_read_raw(struct iio_dev *indio_dev,
 163                            struct iio_chan_spec const *chan,
 164                            int *val,
 165                            int *val2,
 166                            long m)
 167 {
 168         struct as3935_state *st = iio_priv(indio_dev);
 169         int ret;
 170
 171
 172         switch (m) {
 173         case IIO_CHAN_INFO_PROCESSED:
 174         case IIO_CHAN_INFO_RAW:
 175                 *val2 = 0;
 176                 ret = as3935_read(st, AS3935_DATA, val);
 177                 if (ret)
 178                         return ret;
 179
 180                 if (m == IIO_CHAN_INFO_RAW)
 181                         return IIO_VAL_INT;
 182
 183                 /* storm out of range */
 184                 if (*val == AS3935_DATA_MASK)
 185                         return -EINVAL;
 186
 187                 if (m == IIO_CHAN_INFO_PROCESSED)
 188                         *val *= 1000;
 189                 break;
 190         case IIO_CHAN_INFO_SCALE:
 191                 *val = 1000;
 192                 break;
 193         default:
 194                 return -EINVAL;
 195         }
 196
 197         return IIO_VAL_INT;
 198 }
 199
 200 static const struct iio_info as3935_info = {
 201         .driver_module = THIS_MODULE,
 202         .attrs = &as3935_attribute_group,
 203         .read_raw = &as3935_read_raw,
 204 };
 205
 206 static irqreturn_t as3935_trigger_handler(int irq, void *private)
 207 {
 208         struct iio_poll_func *pf = private;
 209         struct iio_dev *indio_dev = pf->indio_dev;
 210         struct as3935_state *st = iio_priv(indio_dev);
 211         int val, ret;
 212
 213         ret = as3935_read(st, AS3935_DATA, &val);
 214         if (ret)
 215                 goto err_read;
 216
 217         st->buffer[0] = val & AS3935_DATA_MASK;
 218         iio_push_to_buffers_with_timestamp(indio_dev, &st->buffer,
 219                                            pf->timestamp);
 220 err_read:
 221         iio_trigger_notify_done(indio_dev->trig);
 222
 223         return IRQ_HANDLED;
 224 }
 225
 226 static const struct iio_trigger_ops iio_interrupt_trigger_ops = {
 227         .owner = THIS_MODULE,
 228 };
 229
 230 static void as3935_event_work(struct work_struct *work)
 231 {
 232         struct as3935_state *st;
 233         int val;
 234
 235         st = container_of(work, struct as3935_state, work.work);
 236
 237         as3935_read(st, AS3935_INT, &val);
 238         val &= AS3935_INT_MASK;
 239
 240         switch (val) {
 241         case AS3935_EVENT_INT:
 242                 iio_trigger_poll(st->trig);
 243                 break;
 244         case AS3935_NOISE_INT:
 245                 dev_warn(&st->spi->dev, "noise level is too high");
 246                 break;
 247         }
 248 }
 249
 250 static irqreturn_t as3935_interrupt_handler(int irq, void *private)
 251 {
 252         struct iio_dev *indio_dev = private;
 253         struct as3935_state *st = iio_priv(indio_dev);
 254
 255         /*
 256          * Delay work for >2 milliseconds after an interrupt to allow
 257          * estimated distance to recalculated.
 258          */
 259
 260         schedule_delayed_work(&st->work, msecs_to_jiffies(3));
 261
 262         return IRQ_HANDLED;
 263 }
 264
 265 static void calibrate_as3935(struct as3935_state *st)
 266 {
 267         mutex_lock(&st->lock);
 268
 269         /* mask disturber interrupt bit */
 270         as3935_write(st, AS3935_INT, BIT(5));
 271
 272         as3935_write(st, AS3935_CALIBRATE, 0x96);
 273         as3935_write(st, AS3935_TUNE_CAP,
 274                 BIT(5) | (st->tune_cap / TUNE_CAP_DIV));
 275
 276         mdelay(2);
 277         as3935_write(st, AS3935_TUNE_CAP, (st->tune_cap / TUNE_CAP_DIV));
 278
 279         mutex_unlock(&st->lock);
 280 }
 281
 282 #ifdef CONFIG_PM_SLEEP
 283 static int as3935_suspend(struct device *dev)
 284 {
 285         struct iio_dev *indio_dev = dev_get_drvdata(dev);
 286         struct as3935_state *st = iio_priv(indio_dev);
 287         int val, ret;
 288
 289         mutex_lock(&st->lock);
 290         ret = as3935_read(st, AS3935_AFE_GAIN, &val);
 291         if (ret)
 292                 goto err_suspend;
 293         val |= AS3935_AFE_PWR_BIT;
 294
 295         ret = as3935_write(st, AS3935_AFE_GAIN, val);
 296
 297 err_suspend:
 298         mutex_unlock(&st->lock);
 299
 300         return ret;
 301 }
 302
 303 static int as3935_resume(struct device *dev)
 304 {
 305         struct iio_dev *indio_dev = dev_get_drvdata(dev);
 306         struct as3935_state *st = iio_priv(indio_dev);
 307         int val, ret;
 308
 309         mutex_lock(&st->lock);
 310         ret = as3935_read(st, AS3935_AFE_GAIN, &val);
 311         if (ret)
 312                 goto err_resume;
 313         val &= ~AS3935_AFE_PWR_BIT;
 314         ret = as3935_write(st, AS3935_AFE_GAIN, val);
 315
 316 err_resume:
 317         mutex_unlock(&st->lock);
 318
 319         return ret;
 320 }
 321
 322 static SIMPLE_DEV_PM_OPS(as3935_pm_ops, as3935_suspend, as3935_resume);
 323 #define AS3935_PM_OPS (&as3935_pm_ops)
 324
 325 #else
 326 #define AS3935_PM_OPS NULL
 327 #endif
 328
 329 static int as3935_probe(struct spi_device *spi)
 330 {
 331         struct iio_dev *indio_dev;
 332         struct iio_trigger *trig;
 333         struct as3935_state *st;
 334         struct device_node *np = spi->dev.of_node;
 335         int ret;
 336
 337         /* Be sure lightning event interrupt is specified */
 338         if (!spi->irq) {
 339                 dev_err(&spi->dev, "unable to get event interrupt\n");
 340                 return -EINVAL;
 341         }
 342
 343         indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
 344         if (!indio_dev)
 345                 return -ENOMEM;
 346
 347         st = iio_priv(indio_dev);
 348         st->spi = spi;
 349         st->tune_cap = 0;
 350
 351         spi_set_drvdata(spi, indio_dev);
 352         mutex_init(&st->lock);
 353         INIT_DELAYED_WORK(&st->work, as3935_event_work);
 354
 355         ret = of_property_read_u32(np,
 356                         "ams,tuning-capacitor-pf", &st->tune_cap);
 357         if (ret) {
 358                 st->tune_cap = 0;
 359                 dev_warn(&spi->dev,
 360                         "no tuning-capacitor-pf set, defaulting to %d",
 361                         st->tune_cap);
 362         }
 363
 364         if (st->tune_cap > MAX_PF_CAP) {
 365                 dev_err(&spi->dev,
 366                         "wrong tuning-capacitor-pf setting of %d\n",
 367                         st->tune_cap);
 368                 return -EINVAL;
 369         }
 370
 371         indio_dev->dev.parent = &spi->dev;
 372         indio_dev->name = spi_get_device_id(spi)->name;
 373         indio_dev->channels = as3935_channels;
 374         indio_dev->num_channels = ARRAY_SIZE(as3935_channels);
 375         indio_dev->modes = INDIO_DIRECT_MODE;
 376         indio_dev->info = &as3935_info;
 377
 378         trig = devm_iio_trigger_alloc(&spi->dev, "%s-dev%d",
 379                                       indio_dev->name, indio_dev->id);
 380
 381         if (!trig)
 382                 return -ENOMEM;
 383
 384         st->trig = trig;
 385         trig->dev.parent = indio_dev->dev.parent;
 386         iio_trigger_set_drvdata(trig, indio_dev);
 387         trig->ops = &iio_interrupt_trigger_ops;
 388
 389         ret = iio_trigger_register(trig);
 390         if (ret) {
 391                 dev_err(&spi->dev, "failed to register trigger\n");
 392                 return ret;
 393         }
 394
 395         ret = iio_triggered_buffer_setup(indio_dev, NULL,
 396                 &as3935_trigger_handler, NULL);
 397
 398         if (ret) {
 399                 dev_err(&spi->dev, "cannot setup iio trigger\n");
 400                 goto unregister_trigger;
 401         }
 402
 403         calibrate_as3935(st);
 404
 405         ret = devm_request_irq(&spi->dev, spi->irq,
 406                                 &as3935_interrupt_handler,
 407                                 IRQF_TRIGGER_RISING,
 408                                 dev_name(&spi->dev),
 409                                 indio_dev);
 410
 411         if (ret) {
 412                 dev_err(&spi->dev, "unable to request irq\n");
 413                 goto unregister_buffer;
 414         }
 415
 416         ret = iio_device_register(indio_dev);
 417         if (ret < 0) {
 418                 dev_err(&spi->dev, "unable to register device\n");
 419                 goto unregister_buffer;
 420         }
 421         return 0;
 422
 423 unregister_buffer:
 424         iio_triggered_buffer_cleanup(indio_dev);
 425
 426 unregister_trigger:
 427         iio_trigger_unregister(st->trig);
 428
 429         return ret;
 430 }
 431
 432 static int as3935_remove(struct spi_device *spi)
 433 {
 434         struct iio_dev *indio_dev = spi_get_drvdata(spi);
 435         struct as3935_state *st = iio_priv(indio_dev);
 436
 437         iio_device_unregister(indio_dev);
 438         iio_triggered_buffer_cleanup(indio_dev);
 439         iio_trigger_unregister(st->trig);
 440
 441         return 0;
 442 }
 443
 444 static const struct of_device_id as3935_of_match[] = {
 445         { .compatible = "ams,as3935", },
 446         { /* sentinel */ },
 447 };
 448 MODULE_DEVICE_TABLE(of, as3935_of_match);
 449
 450 static const struct spi_device_id as3935_id[] = {
 451         {"as3935", 0},
 452         {},
 453 };
 454 MODULE_DEVICE_TABLE(spi, as3935_id);
 455
 456 static struct spi_driver as3935_driver = {
 457         .driver = {
 458                 .name   = "as3935",
 459                 .of_match_table = of_match_ptr(as3935_of_match),
 460                 .pm     = AS3935_PM_OPS,
 461         },
 462         .probe          = as3935_probe,
 463         .remove         = as3935_remove,
 464         .id_table       = as3935_id,
 465 };
 466 module_spi_driver(as3935_driver);
 467
 468 MODULE_AUTHOR("Matt Ranostay <mranostay@gmail.com>");
 469 MODULE_DESCRIPTION("AS3935 lightning sensor");
 470 MODULE_LICENSE("GPL");
 471 MODULE_ALIAS("spi:as3935");