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