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_READ_DATA BIT(14) 54 #define AS3935_ADDRESS(x) ((x) << 8) 55 56 #define MAX_PF_CAP 120 57 #define TUNE_CAP_DIV 8 58 59 struct as3935_state { 60 struct spi_device *spi; 61 struct iio_trigger *trig; 62 struct mutex lock; 63 struct delayed_work work; 64 65 u32 tune_cap; 66 u8 buffer[16]; /* 8-bit data + 56-bit padding + 64-bit timestamp */ 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 BIT(IIO_CHAN_INFO_SCALE), 77 .scan_index = 0, 78 .scan_type = { 79 .sign = 'u', 80 .realbits = 6, 81 .storagebits = 8, 82 }, 83 }, 84 IIO_CHAN_SOFT_TIMESTAMP(1), 85 }; 86 87 static int as3935_read(struct as3935_state *st, unsigned int reg, int *val) 88 { 89 u8 cmd; 90 int ret; 91 92 cmd = (AS3935_READ_DATA | AS3935_ADDRESS(reg)) >> 8; 93 ret = spi_w8r8(st->spi, cmd); 94 if (ret < 0) 95 return ret; 96 *val = ret; 97 98 return 0; 99 } 100 101 static int as3935_write(struct as3935_state *st, 102 unsigned int reg, 103 unsigned int val) 104 { 105 u8 *buf = st->buf; 106 107 buf[0] = AS3935_ADDRESS(reg) >> 8; 108 buf[1] = val; 109 110 return spi_write(st->spi, buf, 2); 111 } 112 113 static ssize_t as3935_sensor_sensitivity_show(struct device *dev, 114 struct device_attribute *attr, 115 char *buf) 116 { 117 struct as3935_state *st = iio_priv(dev_to_iio_dev(dev)); 118 int val, ret; 119 120 ret = as3935_read(st, AS3935_AFE_GAIN, &val); 121 if (ret) 122 return ret; 123 val = (val & AS3935_AFE_MASK) >> 1; 124 125 return sprintf(buf, "%d\n", val); 126 } 127 128 static ssize_t as3935_sensor_sensitivity_store(struct device *dev, 129 struct device_attribute *attr, 130 const char *buf, size_t len) 131 { 132 struct as3935_state *st = iio_priv(dev_to_iio_dev(dev)); 133 unsigned long val; 134 int ret; 135 136 ret = kstrtoul((const char *) buf, 10, &val); 137 if (ret) 138 return -EINVAL; 139 140 if (val > AS3935_AFE_GAIN_MAX) 141 return -EINVAL; 142 143 as3935_write(st, AS3935_AFE_GAIN, val << 1); 144 145 return len; 146 } 147 148 static IIO_DEVICE_ATTR(sensor_sensitivity, S_IRUGO | S_IWUSR, 149 as3935_sensor_sensitivity_show, as3935_sensor_sensitivity_store, 0); 150 151 152 static struct attribute *as3935_attributes[] = { 153 &iio_dev_attr_sensor_sensitivity.dev_attr.attr, 154 NULL, 155 }; 156 157 static const struct attribute_group as3935_attribute_group = { 158 .attrs = as3935_attributes, 159 }; 160 161 static int as3935_read_raw(struct iio_dev *indio_dev, 162 struct iio_chan_spec const *chan, 163 int *val, 164 int *val2, 165 long m) 166 { 167 struct as3935_state *st = iio_priv(indio_dev); 168 int ret; 169 170 171 switch (m) { 172 case IIO_CHAN_INFO_PROCESSED: 173 case IIO_CHAN_INFO_RAW: 174 *val2 = 0; 175 ret = as3935_read(st, AS3935_DATA, val); 176 if (ret) 177 return ret; 178 179 if (m == IIO_CHAN_INFO_RAW) 180 return IIO_VAL_INT; 181 182 /* storm out of range */ 183 if (*val == AS3935_DATA_MASK) 184 return -EINVAL; 185 186 if (m == IIO_CHAN_INFO_PROCESSED) 187 *val *= 1000; 188 break; 189 case IIO_CHAN_INFO_SCALE: 190 *val = 1000; 191 break; 192 default: 193 return -EINVAL; 194 } 195 196 return IIO_VAL_INT; 197 } 198 199 static const struct iio_info as3935_info = { 200 .driver_module = THIS_MODULE, 201 .attrs = &as3935_attribute_group, 202 .read_raw = &as3935_read_raw, 203 }; 204 205 static irqreturn_t as3935_trigger_handler(int irq, void *private) 206 { 207 struct iio_poll_func *pf = private; 208 struct iio_dev *indio_dev = pf->indio_dev; 209 struct as3935_state *st = iio_priv(indio_dev); 210 int val, ret; 211 212 ret = as3935_read(st, AS3935_DATA, &val); 213 if (ret) 214 goto err_read; 215 216 st->buffer[0] = val & AS3935_DATA_MASK; 217 iio_push_to_buffers_with_timestamp(indio_dev, &st->buffer, 218 pf->timestamp); 219 err_read: 220 iio_trigger_notify_done(indio_dev->trig); 221 222 return IRQ_HANDLED; 223 } 224 225 static const struct iio_trigger_ops iio_interrupt_trigger_ops = { 226 .owner = THIS_MODULE, 227 }; 228 229 static void as3935_event_work(struct work_struct *work) 230 { 231 struct as3935_state *st; 232 int val; 233 int ret; 234 235 st = container_of(work, struct as3935_state, work.work); 236 237 ret = as3935_read(st, AS3935_INT, &val); 238 if (ret) { 239 dev_warn(&st->spi->dev, "read error\n"); 240 return; 241 } 242 243 val &= AS3935_INT_MASK; 244 245 switch (val) { 246 case AS3935_EVENT_INT: 247 iio_trigger_poll(st->trig); 248 break; 249 case AS3935_NOISE_INT: 250 dev_warn(&st->spi->dev, "noise level is too high\n"); 251 break; 252 } 253 } 254 255 static irqreturn_t as3935_interrupt_handler(int irq, void *private) 256 { 257 struct iio_dev *indio_dev = private; 258 struct as3935_state *st = iio_priv(indio_dev); 259 260 /* 261 * Delay work for >2 milliseconds after an interrupt to allow 262 * estimated distance to recalculated. 263 */ 264 265 schedule_delayed_work(&st->work, msecs_to_jiffies(3)); 266 267 return IRQ_HANDLED; 268 } 269 270 static void calibrate_as3935(struct as3935_state *st) 271 { 272 mutex_lock(&st->lock); 273 274 /* mask disturber interrupt bit */ 275 as3935_write(st, AS3935_INT, BIT(5)); 276 277 as3935_write(st, AS3935_CALIBRATE, 0x96); 278 as3935_write(st, AS3935_TUNE_CAP, 279 BIT(5) | (st->tune_cap / TUNE_CAP_DIV)); 280 281 mdelay(2); 282 as3935_write(st, AS3935_TUNE_CAP, (st->tune_cap / TUNE_CAP_DIV)); 283 284 mutex_unlock(&st->lock); 285 } 286 287 #ifdef CONFIG_PM_SLEEP 288 static int as3935_suspend(struct device *dev) 289 { 290 struct iio_dev *indio_dev = dev_get_drvdata(dev); 291 struct as3935_state *st = iio_priv(indio_dev); 292 int val, ret; 293 294 mutex_lock(&st->lock); 295 ret = as3935_read(st, AS3935_AFE_GAIN, &val); 296 if (ret) 297 goto err_suspend; 298 val |= AS3935_AFE_PWR_BIT; 299 300 ret = as3935_write(st, AS3935_AFE_GAIN, val); 301 302 err_suspend: 303 mutex_unlock(&st->lock); 304 305 return ret; 306 } 307 308 static int as3935_resume(struct device *dev) 309 { 310 struct iio_dev *indio_dev = dev_get_drvdata(dev); 311 struct as3935_state *st = iio_priv(indio_dev); 312 int val, ret; 313 314 mutex_lock(&st->lock); 315 ret = as3935_read(st, AS3935_AFE_GAIN, &val); 316 if (ret) 317 goto err_resume; 318 val &= ~AS3935_AFE_PWR_BIT; 319 ret = as3935_write(st, AS3935_AFE_GAIN, val); 320 321 err_resume: 322 mutex_unlock(&st->lock); 323 324 return ret; 325 } 326 327 static SIMPLE_DEV_PM_OPS(as3935_pm_ops, as3935_suspend, as3935_resume); 328 #define AS3935_PM_OPS (&as3935_pm_ops) 329 330 #else 331 #define AS3935_PM_OPS NULL 332 #endif 333 334 static int as3935_probe(struct spi_device *spi) 335 { 336 struct iio_dev *indio_dev; 337 struct iio_trigger *trig; 338 struct as3935_state *st; 339 struct device_node *np = spi->dev.of_node; 340 int ret; 341 342 /* Be sure lightning event interrupt is specified */ 343 if (!spi->irq) { 344 dev_err(&spi->dev, "unable to get event interrupt\n"); 345 return -EINVAL; 346 } 347 348 indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st)); 349 if (!indio_dev) 350 return -ENOMEM; 351 352 st = iio_priv(indio_dev); 353 st->spi = spi; 354 355 spi_set_drvdata(spi, indio_dev); 356 mutex_init(&st->lock); 357 INIT_DELAYED_WORK(&st->work, as3935_event_work); 358 359 ret = of_property_read_u32(np, 360 "ams,tuning-capacitor-pf", &st->tune_cap); 361 if (ret) { 362 st->tune_cap = 0; 363 dev_warn(&spi->dev, 364 "no tuning-capacitor-pf set, defaulting to %d", 365 st->tune_cap); 366 } 367 368 if (st->tune_cap > MAX_PF_CAP) { 369 dev_err(&spi->dev, 370 "wrong tuning-capacitor-pf setting of %d\n", 371 st->tune_cap); 372 return -EINVAL; 373 } 374 375 indio_dev->dev.parent = &spi->dev; 376 indio_dev->name = spi_get_device_id(spi)->name; 377 indio_dev->channels = as3935_channels; 378 indio_dev->num_channels = ARRAY_SIZE(as3935_channels); 379 indio_dev->modes = INDIO_DIRECT_MODE; 380 indio_dev->info = &as3935_info; 381 382 trig = devm_iio_trigger_alloc(&spi->dev, "%s-dev%d", 383 indio_dev->name, indio_dev->id); 384 385 if (!trig) 386 return -ENOMEM; 387 388 st->trig = trig; 389 trig->dev.parent = indio_dev->dev.parent; 390 iio_trigger_set_drvdata(trig, indio_dev); 391 trig->ops = &iio_interrupt_trigger_ops; 392 393 ret = iio_trigger_register(trig); 394 if (ret) { 395 dev_err(&spi->dev, "failed to register trigger\n"); 396 return ret; 397 } 398 399 ret = iio_triggered_buffer_setup(indio_dev, iio_pollfunc_store_time, 400 &as3935_trigger_handler, NULL); 401 402 if (ret) { 403 dev_err(&spi->dev, "cannot setup iio trigger\n"); 404 goto unregister_trigger; 405 } 406 407 calibrate_as3935(st); 408 409 ret = devm_request_irq(&spi->dev, spi->irq, 410 &as3935_interrupt_handler, 411 IRQF_TRIGGER_RISING, 412 dev_name(&spi->dev), 413 indio_dev); 414 415 if (ret) { 416 dev_err(&spi->dev, "unable to request irq\n"); 417 goto unregister_buffer; 418 } 419 420 ret = iio_device_register(indio_dev); 421 if (ret < 0) { 422 dev_err(&spi->dev, "unable to register device\n"); 423 goto unregister_buffer; 424 } 425 return 0; 426 427 unregister_buffer: 428 iio_triggered_buffer_cleanup(indio_dev); 429 430 unregister_trigger: 431 iio_trigger_unregister(st->trig); 432 433 return ret; 434 } 435 436 static int as3935_remove(struct spi_device *spi) 437 { 438 struct iio_dev *indio_dev = spi_get_drvdata(spi); 439 struct as3935_state *st = iio_priv(indio_dev); 440 441 iio_device_unregister(indio_dev); 442 iio_triggered_buffer_cleanup(indio_dev); 443 iio_trigger_unregister(st->trig); 444 445 return 0; 446 } 447 448 static const struct of_device_id as3935_of_match[] = { 449 { .compatible = "ams,as3935", }, 450 { /* sentinel */ }, 451 }; 452 MODULE_DEVICE_TABLE(of, as3935_of_match); 453 454 static const struct spi_device_id as3935_id[] = { 455 {"as3935", 0}, 456 {}, 457 }; 458 MODULE_DEVICE_TABLE(spi, as3935_id); 459 460 static struct spi_driver as3935_driver = { 461 .driver = { 462 .name = "as3935", 463 .of_match_table = of_match_ptr(as3935_of_match), 464 .pm = AS3935_PM_OPS, 465 }, 466 .probe = as3935_probe, 467 .remove = as3935_remove, 468 .id_table = as3935_id, 469 }; 470 module_spi_driver(as3935_driver); 471 472 MODULE_AUTHOR("Matt Ranostay <mranostay@gmail.com>"); 473 MODULE_DESCRIPTION("AS3935 lightning sensor"); 474 MODULE_LICENSE("GPL"); 475