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/mod_devicetable.h>
  41 #include <linux/module.h>
  42 #include <linux/platform_device.h>
  43 #include <linux/property.h>
  44 #include <linux/sched.h>
  45 #include <linux/interrupt.h>
  46 #include <linux/delay.h>
  47 #include <linux/pm_runtime.h>
  48 #include <linux/iio/iio.h>
  49 #include <linux/iio/sysfs.h>
  50
  51 struct srf04_cfg {
  52         unsigned long trigger_pulse_us;
  53 };
  54
  55 struct srf04_data {
  56         struct device           *dev;
  57         struct gpio_desc        *gpiod_trig;
  58         struct gpio_desc        *gpiod_echo;
  59         struct gpio_desc        *gpiod_power;
  60         struct mutex            lock;
  61         int                     irqnr;
  62         ktime_t                 ts_rising;
  63         ktime_t                 ts_falling;
  64         struct completion       rising;
  65         struct completion       falling;
  66         const struct srf04_cfg  *cfg;
  67         int                     startup_time_ms;
  68 };
  69
  70 static const struct srf04_cfg srf04_cfg = {
  71         .trigger_pulse_us = 10,
  72 };
  73
  74 static const struct srf04_cfg mb_lv_cfg = {
  75         .trigger_pulse_us = 20,
  76 };
  77
  78 static irqreturn_t srf04_handle_irq(int irq, void *dev_id)
  79 {
  80         struct iio_dev *indio_dev = dev_id;
  81         struct srf04_data *data = iio_priv(indio_dev);
  82         ktime_t now = ktime_get();
  83
  84         if (gpiod_get_value(data->gpiod_echo)) {
  85                 data->ts_rising = now;
  86                 complete(&data->rising);
  87         } else {
  88                 data->ts_falling = now;
  89                 complete(&data->falling);
  90         }
  91
  92         return IRQ_HANDLED;
  93 }
  94
  95 static int srf04_read(struct srf04_data *data)
  96 {
  97         int ret;
  98         ktime_t ktime_dt;
  99         u64 dt_ns;
 100         u32 time_ns, distance_mm;
 101
 102         if (data->gpiod_power) {
 103                 ret = pm_runtime_resume_and_get(data->dev);
 104                 if (ret < 0)
 105                         return ret;
 106         }
 107         /*
 108          * just one read-echo-cycle can take place at a time
 109          * ==> lock against concurrent reading calls
 110          */
 111         mutex_lock(&data->lock);
 112
 113         reinit_completion(&data->rising);
 114         reinit_completion(&data->falling);
 115
 116         gpiod_set_value(data->gpiod_trig, 1);
 117         udelay(data->cfg->trigger_pulse_us);
 118         gpiod_set_value(data->gpiod_trig, 0);
 119
 120         if (data->gpiod_power) {
 121                 pm_runtime_mark_last_busy(data->dev);
 122                 pm_runtime_put_autosuspend(data->dev);
 123         }
 124
 125         /* it should not take more than 20 ms until echo is rising */
 126         ret = wait_for_completion_killable_timeout(&data->rising, HZ/50);
 127         if (ret < 0) {
 128                 mutex_unlock(&data->lock);
 129                 return ret;
 130         } else if (ret == 0) {
 131                 mutex_unlock(&data->lock);
 132                 return -ETIMEDOUT;
 133         }
 134
 135         /* it cannot take more than 50 ms until echo is falling */
 136         ret = wait_for_completion_killable_timeout(&data->falling, HZ/20);
 137         if (ret < 0) {
 138                 mutex_unlock(&data->lock);
 139                 return ret;
 140         } else if (ret == 0) {
 141                 mutex_unlock(&data->lock);
 142                 return -ETIMEDOUT;
 143         }
 144
 145         ktime_dt = ktime_sub(data->ts_falling, data->ts_rising);
 146
 147         mutex_unlock(&data->lock);
 148
 149         dt_ns = ktime_to_ns(ktime_dt);
 150         /*
 151          * measuring more than 6,45 meters is beyond the capabilities of
 152          * the supported sensors
 153          * ==> filter out invalid results for not measuring echos of
 154          *     another us sensor
 155          *
 156          * formula:
 157          *         distance     6,45 * 2 m
 158          * time = ---------- = ------------ = 40438871 ns
 159          *          speed         319 m/s
 160          *
 161          * using a minimum speed at -20 °C of 319 m/s
 162          */
 163         if (dt_ns > 40438871)
 164                 return -EIO;
 165
 166         time_ns = dt_ns;
 167
 168         /*
 169          * the speed as function of the temperature is approximately:
 170          *
 171          * speed = 331,5 + 0,6 * Temp
 172          *   with Temp in °C
 173          *   and speed in m/s
 174          *
 175          * use 343,5 m/s as ultrasonic speed at 20 °C here in absence of the
 176          * temperature
 177          *
 178          * therefore:
 179          *             time     343,5     time * 106
 180          * distance = ------ * ------- = ------------
 181          *             10^6         2         617176
 182          *   with time in ns
 183          *   and distance in mm (one way)
 184          *
 185          * because we limit to 6,45 meters the multiplication with 106 just
 186          * fits into 32 bit
 187          */
 188         distance_mm = time_ns * 106 / 617176;
 189
 190         return distance_mm;
 191 }
 192
 193 static int srf04_read_raw(struct iio_dev *indio_dev,
 194                             struct iio_chan_spec const *channel, int *val,
 195                             int *val2, long info)
 196 {
 197         struct srf04_data *data = iio_priv(indio_dev);
 198         int ret;
 199
 200         if (channel->type != IIO_DISTANCE)
 201                 return -EINVAL;
 202
 203         switch (info) {
 204         case IIO_CHAN_INFO_RAW:
 205                 ret = srf04_read(data);
 206                 if (ret < 0)
 207                         return ret;
 208                 *val = ret;
 209                 return IIO_VAL_INT;
 210         case IIO_CHAN_INFO_SCALE:
 211                 /*
 212                  * theoretical maximum resolution is 3 mm
 213                  * 1 LSB is 1 mm
 214                  */
 215                 *val = 0;
 216                 *val2 = 1000;
 217                 return IIO_VAL_INT_PLUS_MICRO;
 218         default:
 219                 return -EINVAL;
 220         }
 221 }
 222
 223 static const struct iio_info srf04_iio_info = {
 224         .read_raw               = srf04_read_raw,
 225 };
 226
 227 static const struct iio_chan_spec srf04_chan_spec[] = {
 228         {
 229                 .type = IIO_DISTANCE,
 230                 .info_mask_separate =
 231                                 BIT(IIO_CHAN_INFO_RAW) |
 232                                 BIT(IIO_CHAN_INFO_SCALE),
 233         },
 234 };
 235
 236 static const struct of_device_id of_srf04_match[] = {
 237         { .compatible = "devantech,srf04", .data = &srf04_cfg },
 238         { .compatible = "maxbotix,mb1000", .data = &mb_lv_cfg },
 239         { .compatible = "maxbotix,mb1010", .data = &mb_lv_cfg },
 240         { .compatible = "maxbotix,mb1020", .data = &mb_lv_cfg },
 241         { .compatible = "maxbotix,mb1030", .data = &mb_lv_cfg },
 242         { .compatible = "maxbotix,mb1040", .data = &mb_lv_cfg },
 243         {},
 244 };
 245
 246 MODULE_DEVICE_TABLE(of, of_srf04_match);
 247
 248 static int srf04_probe(struct platform_device *pdev)
 249 {
 250         struct device *dev = &pdev->dev;
 251         struct srf04_data *data;
 252         struct iio_dev *indio_dev;
 253         int ret;
 254
 255         indio_dev = devm_iio_device_alloc(dev, sizeof(struct srf04_data));
 256         if (!indio_dev) {
 257                 dev_err(dev, "failed to allocate IIO device\n");
 258                 return -ENOMEM;
 259         }
 260
 261         data = iio_priv(indio_dev);
 262         data->dev = dev;
 263         data->cfg = device_get_match_data(dev);
 264
 265         mutex_init(&data->lock);
 266         init_completion(&data->rising);
 267         init_completion(&data->falling);
 268
 269         data->gpiod_trig = devm_gpiod_get(dev, "trig", GPIOD_OUT_LOW);
 270         if (IS_ERR(data->gpiod_trig)) {
 271                 dev_err(dev, "failed to get trig-gpios: err=%ld\n",
 272                                         PTR_ERR(data->gpiod_trig));
 273                 return PTR_ERR(data->gpiod_trig);
 274         }
 275
 276         data->gpiod_echo = devm_gpiod_get(dev, "echo", GPIOD_IN);
 277         if (IS_ERR(data->gpiod_echo)) {
 278                 dev_err(dev, "failed to get echo-gpios: err=%ld\n",
 279                                         PTR_ERR(data->gpiod_echo));
 280                 return PTR_ERR(data->gpiod_echo);
 281         }
 282
 283         data->gpiod_power = devm_gpiod_get_optional(dev, "power",
 284                                                                 GPIOD_OUT_LOW);
 285         if (IS_ERR(data->gpiod_power)) {
 286                 dev_err(dev, "failed to get power-gpios: err=%ld\n",
 287                                                 PTR_ERR(data->gpiod_power));
 288                 return PTR_ERR(data->gpiod_power);
 289         }
 290         if (data->gpiod_power) {
 291                 data->startup_time_ms = 100;
 292                 device_property_read_u32(dev, "startup-time-ms", &data->startup_time_ms);
 293                 dev_dbg(dev, "using power gpio: startup-time-ms=%d\n",
 294                                                         data->startup_time_ms);
 295         }
 296
 297         if (gpiod_cansleep(data->gpiod_echo)) {
 298                 dev_err(data->dev, "cansleep-GPIOs not supported\n");
 299                 return -ENODEV;
 300         }
 301
 302         data->irqnr = gpiod_to_irq(data->gpiod_echo);
 303         if (data->irqnr < 0) {
 304                 dev_err(data->dev, "gpiod_to_irq: %d\n", data->irqnr);
 305                 return data->irqnr;
 306         }
 307
 308         ret = devm_request_irq(dev, data->irqnr, srf04_handle_irq,
 309                         IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
 310                         pdev->name, indio_dev);
 311         if (ret < 0) {
 312                 dev_err(data->dev, "request_irq: %d\n", ret);
 313                 return ret;
 314         }
 315
 316         platform_set_drvdata(pdev, indio_dev);
 317
 318         indio_dev->name = "srf04";
 319         indio_dev->info = &srf04_iio_info;
 320         indio_dev->modes = INDIO_DIRECT_MODE;
 321         indio_dev->channels = srf04_chan_spec;
 322         indio_dev->num_channels = ARRAY_SIZE(srf04_chan_spec);
 323
 324         ret = iio_device_register(indio_dev);
 325         if (ret < 0) {
 326                 dev_err(data->dev, "iio_device_register: %d\n", ret);
 327                 return ret;
 328         }
 329
 330         if (data->gpiod_power) {
 331                 pm_runtime_set_autosuspend_delay(data->dev, 1000);
 332                 pm_runtime_use_autosuspend(data->dev);
 333
 334                 ret = pm_runtime_set_active(data->dev);
 335                 if (ret) {
 336                         dev_err(data->dev, "pm_runtime_set_active: %d\n", ret);
 337                         iio_device_unregister(indio_dev);
 338                 }
 339
 340                 pm_runtime_enable(data->dev);
 341                 pm_runtime_idle(data->dev);
 342         }
 343
 344         return ret;
 345 }
 346
 347 static void srf04_remove(struct platform_device *pdev)
 348 {
 349         struct iio_dev *indio_dev = platform_get_drvdata(pdev);
 350         struct srf04_data *data = iio_priv(indio_dev);
 351
 352         iio_device_unregister(indio_dev);
 353
 354         if (data->gpiod_power) {
 355                 pm_runtime_disable(data->dev);
 356                 pm_runtime_set_suspended(data->dev);
 357         }
 358 }
 359
 360 static int  srf04_pm_runtime_suspend(struct device *dev)
 361 {
 362         struct platform_device *pdev = container_of(dev,
 363                                                 struct platform_device, dev);
 364         struct iio_dev *indio_dev = platform_get_drvdata(pdev);
 365         struct srf04_data *data = iio_priv(indio_dev);
 366
 367         gpiod_set_value(data->gpiod_power, 0);
 368
 369         return 0;
 370 }
 371
 372 static int srf04_pm_runtime_resume(struct device *dev)
 373 {
 374         struct platform_device *pdev = container_of(dev,
 375                                                 struct platform_device, dev);
 376         struct iio_dev *indio_dev = platform_get_drvdata(pdev);
 377         struct srf04_data *data = iio_priv(indio_dev);
 378
 379         gpiod_set_value(data->gpiod_power, 1);
 380         msleep(data->startup_time_ms);
 381
 382         return 0;
 383 }
 384
 385 static const struct dev_pm_ops srf04_pm_ops = {
 386         RUNTIME_PM_OPS(srf04_pm_runtime_suspend,
 387                        srf04_pm_runtime_resume, NULL)
 388 };
 389
 390 static struct platform_driver srf04_driver = {
 391         .probe          = srf04_probe,
 392         .remove_new     = srf04_remove,
 393         .driver         = {
 394                 .name           = "srf04-gpio",
 395                 .of_match_table = of_srf04_match,
 396                 .pm             = pm_ptr(&srf04_pm_ops),
 397         },
 398 };
 399
 400 module_platform_driver(srf04_driver);
 401
 402 MODULE_AUTHOR("Andreas Klinger <ak@it-klinger.de>");
 403 MODULE_DESCRIPTION("SRF04 ultrasonic sensor for distance measuring using GPIOs");
 404 MODULE_LICENSE("GPL");
 405 MODULE_ALIAS("platform:srf04");