drivers/iio/proximity/srf04.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * SRF04: ultrasonic sensor for distance measuring by using GPIOs
   4  *
   5  * Copyright (c) 2017 Andreas Klinger <ak@it-klinger.de>
   6  *
   7  * For details about the device see:
   8  * https://www.robot-electronics.co.uk/htm/srf04tech.htm
   9  *
  10  * the measurement cycle as timing diagram looks like:
  11  *
  12  *          +---+
  13  * GPIO     |   |
  14  * trig:  --+   +------------------------------------------------------
  15  *          ^   ^
  16  *          |<->|
  17  *         udelay(trigger_pulse_us)
  18  *
  19  * ultra           +-+ +-+ +-+
  20  * sonic           | | | | | |
  21  * burst: ---------+ +-+ +-+ +-----------------------------------------
  22  *                           .
  23  * ultra                     .              +-+ +-+ +-+
  24  * sonic                     .              | | | | | |
  25  * echo:  ----------------------------------+ +-+ +-+ +----------------
  26  *                           .                        .
  27  *                           +------------------------+
  28  * GPIO                      |                        |
  29  * echo:  -------------------+                        +---------------
  30  *                           ^                        ^
  31  *                           interrupt                interrupt
  32  *                           (ts_rising)              (ts_falling)
  33  *                           |<---------------------->|
  34  *                              pulse time measured
  35  *                              --> one round trip of ultra sonic waves
  36  */
  37 #include <linux/err.h>
  38 #include <linux/gpio/consumer.h>
  39 #include <linux/kernel.h>
  40 #include <linux/module.h>
  41 #include <linux/of.h>
  42 #include <linux/of_device.h>
  43 #include <linux/platform_device.h>
  44 #include <linux/property.h>
  45 #include <linux/sched.h>
  46 #include <linux/interrupt.h>
  47 #include <linux/delay.h>
  48 #include <linux/pm_runtime.h>
  49 #include <linux/iio/iio.h>
  50 #include <linux/iio/sysfs.h>
  51
  52 struct srf04_cfg {
  53         unsigned long trigger_pulse_us;
  54 };
  55
  56 struct srf04_data {
  57         struct device           *dev;
  58         struct gpio_desc        *gpiod_trig;
  59         struct gpio_desc        *gpiod_echo;
  60         struct gpio_desc        *gpiod_power;
  61         struct mutex            lock;
  62         int                     irqnr;
  63         ktime_t                 ts_rising;
  64         ktime_t                 ts_falling;
  65         struct completion       rising;
  66         struct completion       falling;
  67         const struct srf04_cfg  *cfg;
  68         int                     startup_time_ms;
  69 };
  70
  71 static const struct srf04_cfg srf04_cfg = {
  72         .trigger_pulse_us = 10,
  73 };
  74
  75 static const struct srf04_cfg mb_lv_cfg = {
  76         .trigger_pulse_us = 20,
  77 };
  78
  79 static irqreturn_t srf04_handle_irq(int irq, void *dev_id)
  80 {
  81         struct iio_dev *indio_dev = dev_id;
  82         struct srf04_data *data = iio_priv(indio_dev);
  83         ktime_t now = ktime_get();
  84
  85         if (gpiod_get_value(data->gpiod_echo)) {
  86                 data->ts_rising = now;
  87                 complete(&data->rising);
  88         } else {
  89                 data->ts_falling = now;
  90                 complete(&data->falling);
  91         }
  92
  93         return IRQ_HANDLED;
  94 }
  95
  96 static int srf04_read(struct srf04_data *data)
  97 {
  98         int ret;
  99         ktime_t ktime_dt;
 100         u64 dt_ns;
 101         u32 time_ns, distance_mm;
 102
 103         if (data->gpiod_power)
 104                 pm_runtime_get_sync(data->dev);
 105
 106         /*
 107          * just one read-echo-cycle can take place at a time
 108          * ==> lock against concurrent reading calls
 109          */
 110         mutex_lock(&data->lock);
 111
 112         reinit_completion(&data->rising);
 113         reinit_completion(&data->falling);
 114
 115         gpiod_set_value(data->gpiod_trig, 1);
 116         udelay(data->cfg->trigger_pulse_us);
 117         gpiod_set_value(data->gpiod_trig, 0);
 118
 119         if (data->gpiod_power) {
 120                 pm_runtime_mark_last_busy(data->dev);
 121                 pm_runtime_put_autosuspend(data->dev);
 122         }
 123
 124         /* it should not take more than 20 ms until echo is rising */
 125         ret = wait_for_completion_killable_timeout(&data->rising, HZ/50);
 126         if (ret < 0) {
 127                 mutex_unlock(&data->lock);
 128                 return ret;
 129         } else if (ret == 0) {
 130                 mutex_unlock(&data->lock);
 131                 return -ETIMEDOUT;
 132         }
 133
 134         /* it cannot take more than 50 ms until echo is falling */
 135         ret = wait_for_completion_killable_timeout(&data->falling, HZ/20);
 136         if (ret < 0) {
 137                 mutex_unlock(&data->lock);
 138                 return ret;
 139         } else if (ret == 0) {
 140                 mutex_unlock(&data->lock);
 141                 return -ETIMEDOUT;
 142         }
 143
 144         ktime_dt = ktime_sub(data->ts_falling, data->ts_rising);
 145
 146         mutex_unlock(&data->lock);
 147
 148         dt_ns = ktime_to_ns(ktime_dt);
 149         /*
 150          * measuring more than 6,45 meters is beyond the capabilities of
 151          * the supported sensors
 152          * ==> filter out invalid results for not measuring echos of
 153          *     another us sensor
 154          *
 155          * formula:
 156          *         distance     6,45 * 2 m
 157          * time = ---------- = ------------ = 40438871 ns
 158          *          speed         319 m/s
 159          *
 160          * using a minimum speed at -20 °C of 319 m/s
 161          */
 162         if (dt_ns > 40438871)
 163                 return -EIO;
 164
 165         time_ns = dt_ns;
 166
 167         /*
 168          * the speed as function of the temperature is approximately:
 169          *
 170          * speed = 331,5 + 0,6 * Temp
 171          *   with Temp in °C
 172          *   and speed in m/s
 173          *
 174          * use 343,5 m/s as ultrasonic speed at 20 °C here in absence of the
 175          * temperature
 176          *
 177          * therefore:
 178          *             time     343,5     time * 106
 179          * distance = ------ * ------- = ------------
 180          *             10^6         2         617176
 181          *   with time in ns
 182          *   and distance in mm (one way)
 183          *
 184          * because we limit to 6,45 meters the multiplication with 106 just
 185          * fits into 32 bit
 186          */
 187         distance_mm = time_ns * 106 / 617176;
 188
 189         return distance_mm;
 190 }
 191
 192 static int srf04_read_raw(struct iio_dev *indio_dev,
 193                             struct iio_chan_spec const *channel, int *val,
 194                             int *val2, long info)
 195 {
 196         struct srf04_data *data = iio_priv(indio_dev);
 197         int ret;
 198
 199         if (channel->type != IIO_DISTANCE)
 200                 return -EINVAL;
 201
 202         switch (info) {
 203         case IIO_CHAN_INFO_RAW:
 204                 ret = srf04_read(data);
 205                 if (ret < 0)
 206                         return ret;
 207                 *val = ret;
 208                 return IIO_VAL_INT;
 209         case IIO_CHAN_INFO_SCALE:
 210                 /*
 211                  * theoretical maximum resolution is 3 mm
 212                  * 1 LSB is 1 mm
 213                  */
 214                 *val = 0;
 215                 *val2 = 1000;
 216                 return IIO_VAL_INT_PLUS_MICRO;
 217         default:
 218                 return -EINVAL;
 219         }
 220 }
 221
 222 static const struct iio_info srf04_iio_info = {
 223         .read_raw               = srf04_read_raw,
 224 };
 225
 226 static const struct iio_chan_spec srf04_chan_spec[] = {
 227         {
 228                 .type = IIO_DISTANCE,
 229                 .info_mask_separate =
 230                                 BIT(IIO_CHAN_INFO_RAW) |
 231                                 BIT(IIO_CHAN_INFO_SCALE),
 232         },
 233 };
 234
 235 static const struct of_device_id of_srf04_match[] = {
 236         { .compatible = "devantech,srf04", .data = &srf04_cfg},
 237         { .compatible = "maxbotix,mb1000", .data = &mb_lv_cfg},
 238         { .compatible = "maxbotix,mb1010", .data = &mb_lv_cfg},
 239         { .compatible = "maxbotix,mb1020", .data = &mb_lv_cfg},
 240         { .compatible = "maxbotix,mb1030", .data = &mb_lv_cfg},
 241         { .compatible = "maxbotix,mb1040", .data = &mb_lv_cfg},
 242         {},
 243 };
 244
 245 MODULE_DEVICE_TABLE(of, of_srf04_match);
 246
 247 static int srf04_probe(struct platform_device *pdev)
 248 {
 249         struct device *dev = &pdev->dev;
 250         struct srf04_data *data;
 251         struct iio_dev *indio_dev;
 252         int ret;
 253
 254         indio_dev = devm_iio_device_alloc(dev, sizeof(struct srf04_data));
 255         if (!indio_dev) {
 256                 dev_err(dev, "failed to allocate IIO device\n");
 257                 return -ENOMEM;
 258         }
 259
 260         data = iio_priv(indio_dev);
 261         data->dev = dev;
 262         data->cfg = of_match_device(of_srf04_match, dev)->data;
 263
 264         mutex_init(&data->lock);
 265         init_completion(&data->rising);
 266         init_completion(&data->falling);
 267
 268         data->gpiod_trig = devm_gpiod_get(dev, "trig", GPIOD_OUT_LOW);
 269         if (IS_ERR(data->gpiod_trig)) {
 270                 dev_err(dev, "failed to get trig-gpios: err=%ld\n",
 271                                         PTR_ERR(data->gpiod_trig));
 272                 return PTR_ERR(data->gpiod_trig);
 273         }
 274
 275         data->gpiod_echo = devm_gpiod_get(dev, "echo", GPIOD_IN);
 276         if (IS_ERR(data->gpiod_echo)) {
 277                 dev_err(dev, "failed to get echo-gpios: err=%ld\n",
 278                                         PTR_ERR(data->gpiod_echo));
 279                 return PTR_ERR(data->gpiod_echo);
 280         }
 281
 282         data->gpiod_power = devm_gpiod_get_optional(dev, "power",
 283                                                                 GPIOD_OUT_LOW);
 284         if (IS_ERR(data->gpiod_power)) {
 285                 dev_err(dev, "failed to get power-gpios: err=%ld\n",
 286                                                 PTR_ERR(data->gpiod_power));
 287                 return PTR_ERR(data->gpiod_power);
 288         }
 289         if (data->gpiod_power) {
 290
 291                 if (of_property_read_u32(dev->of_node, "startup-time-ms",
 292                                                 &data->startup_time_ms))
 293                         data->startup_time_ms = 100;
 294                 dev_dbg(dev, "using power gpio: startup-time-ms=%d\n",
 295                                                         data->startup_time_ms);
 296         }
 297
 298         if (gpiod_cansleep(data->gpiod_echo)) {
 299                 dev_err(data->dev, "cansleep-GPIOs not supported\n");
 300                 return -ENODEV;
 301         }
 302
 303         data->irqnr = gpiod_to_irq(data->gpiod_echo);
 304         if (data->irqnr < 0) {
 305                 dev_err(data->dev, "gpiod_to_irq: %d\n", data->irqnr);
 306                 return data->irqnr;
 307         }
 308
 309         ret = devm_request_irq(dev, data->irqnr, srf04_handle_irq,
 310                         IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
 311                         pdev->name, indio_dev);
 312         if (ret < 0) {
 313                 dev_err(data->dev, "request_irq: %d\n", ret);
 314                 return ret;
 315         }
 316
 317         platform_set_drvdata(pdev, indio_dev);
 318
 319         indio_dev->name = "srf04";
 320         indio_dev->info = &srf04_iio_info;
 321         indio_dev->modes = INDIO_DIRECT_MODE;
 322         indio_dev->channels = srf04_chan_spec;
 323         indio_dev->num_channels = ARRAY_SIZE(srf04_chan_spec);
 324
 325         ret = iio_device_register(indio_dev);
 326         if (ret < 0) {
 327                 dev_err(data->dev, "iio_device_register: %d\n", ret);
 328                 return ret;
 329         }
 330
 331         if (data->gpiod_power) {
 332                 pm_runtime_set_autosuspend_delay(data->dev, 1000);
 333                 pm_runtime_use_autosuspend(data->dev);
 334
 335                 ret = pm_runtime_set_active(data->dev);
 336                 if (ret) {
 337                         dev_err(data->dev, "pm_runtime_set_active: %d\n", ret);
 338                         iio_device_unregister(indio_dev);
 339                 }
 340
 341                 pm_runtime_enable(data->dev);
 342                 pm_runtime_idle(data->dev);
 343         }
 344
 345         return ret;
 346 }
 347
 348 static int srf04_remove(struct platform_device *pdev)
 349 {
 350         struct iio_dev *indio_dev = platform_get_drvdata(pdev);
 351         struct srf04_data *data = iio_priv(indio_dev);
 352
 353         iio_device_unregister(indio_dev);
 354
 355         if (data->gpiod_power) {
 356                 pm_runtime_disable(data->dev);
 357                 pm_runtime_set_suspended(data->dev);
 358         }
 359
 360         return 0;
 361 }
 362
 363 static int __maybe_unused srf04_pm_runtime_suspend(struct device *dev)
 364 {
 365         struct platform_device *pdev = container_of(dev,
 366                                                 struct platform_device, dev);
 367         struct iio_dev *indio_dev = platform_get_drvdata(pdev);
 368         struct srf04_data *data = iio_priv(indio_dev);
 369
 370         gpiod_set_value(data->gpiod_power, 0);
 371
 372         return 0;
 373 }
 374
 375 static int __maybe_unused srf04_pm_runtime_resume(struct device *dev)
 376 {
 377         struct platform_device *pdev = container_of(dev,
 378                                                 struct platform_device, dev);
 379         struct iio_dev *indio_dev = platform_get_drvdata(pdev);
 380         struct srf04_data *data = iio_priv(indio_dev);
 381
 382         gpiod_set_value(data->gpiod_power, 1);
 383         msleep(data->startup_time_ms);
 384
 385         return 0;
 386 }
 387
 388 static const struct dev_pm_ops srf04_pm_ops = {
 389         SET_RUNTIME_PM_OPS(srf04_pm_runtime_suspend,
 390                                 srf04_pm_runtime_resume, NULL)
 391 };
 392
 393 static struct platform_driver srf04_driver = {
 394         .probe          = srf04_probe,
 395         .remove         = srf04_remove,
 396         .driver         = {
 397                 .name           = "srf04-gpio",
 398                 .of_match_table = of_srf04_match,
 399                 .pm             = &srf04_pm_ops,
 400         },
 401 };
 402
 403 module_platform_driver(srf04_driver);
 404
 405 MODULE_AUTHOR("Andreas Klinger <ak@it-klinger.de>");
 406 MODULE_DESCRIPTION("SRF04 ultrasonic sensor for distance measuring using GPIOs");
 407 MODULE_LICENSE("GPL");
 408 MODULE_ALIAS("platform:srf04");