drivers/iio/proximity/ping.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * PING: ultrasonic sensor for distance measuring by using only one GPIOs
   4  *
   5  * Copyright (c) 2019 Andreas Klinger <ak@it-klinger.de>
   6  *
   7  * For details about the devices see:
   8  * http://parallax.com/sites/default/files/downloads/28041-LaserPING-2m-Rangefinder-Guide.pdf
   9  * http://parallax.com/sites/default/files/downloads/28015-PING-Documentation-v1.6.pdf
  10  *
  11  * the measurement cycle as timing diagram looks like:
  12  *
  13  * GPIO      ___              ________________________
  14  * ping:  __/   \____________/                        \________________
  15  *          ^   ^            ^                        ^
  16  *          |<->|            interrupt                interrupt
  17  *         udelay(5)         (ts_rising)              (ts_falling)
  18  *                           |<---------------------->|
  19  *                           .  pulse time measured   .
  20  *                           .  --> one round trip of ultra sonic waves
  21  * ultra                     .                        .
  22  * sonic            _   _   _.                        .
  23  * burst: _________/ \_/ \_/ \_________________________________________
  24  *                                                    .
  25  * ultra                                              .
  26  * sonic                                     _   _   _.
  27  * echo:  __________________________________/ \_/ \_/ \________________
  28  */
  29 #include <linux/err.h>
  30 #include <linux/gpio/consumer.h>
  31 #include <linux/kernel.h>
  32 #include <linux/mod_devicetable.h>
  33 #include <linux/module.h>
  34 #include <linux/platform_device.h>
  35 #include <linux/property.h>
  36 #include <linux/sched.h>
  37 #include <linux/interrupt.h>
  38 #include <linux/delay.h>
  39 #include <linux/iio/iio.h>
  40 #include <linux/iio/sysfs.h>
  41
  42 struct ping_cfg {
  43         unsigned long   trigger_pulse_us;       /* length of trigger pulse */
  44         int             laserping_error;        /* support error code in */
  45                                                 /*   pulse width of laser */
  46                                                 /*   ping sensors */
  47         s64             timeout_ns;             /* timeout in ns */
  48 };
  49
  50 struct ping_data {
  51         struct device           *dev;
  52         struct gpio_desc        *gpiod_ping;
  53         struct mutex            lock;
  54         int                     irqnr;
  55         ktime_t                 ts_rising;
  56         ktime_t                 ts_falling;
  57         struct completion       rising;
  58         struct completion       falling;
  59         const struct ping_cfg   *cfg;
  60 };
  61
  62 static const struct ping_cfg pa_ping_cfg = {
  63         .trigger_pulse_us       = 5,
  64         .laserping_error        = 0,
  65         .timeout_ns             = 18500000,     /* 3 meters */
  66 };
  67
  68 static const struct ping_cfg pa_laser_ping_cfg = {
  69         .trigger_pulse_us       = 5,
  70         .laserping_error        = 1,
  71         .timeout_ns             = 15500000,     /* 2 meters plus error codes */
  72 };
  73
  74 static irqreturn_t ping_handle_irq(int irq, void *dev_id)
  75 {
  76         struct iio_dev *indio_dev = dev_id;
  77         struct ping_data *data = iio_priv(indio_dev);
  78         ktime_t now = ktime_get();
  79
  80         if (gpiod_get_value(data->gpiod_ping)) {
  81                 data->ts_rising = now;
  82                 complete(&data->rising);
  83         } else {
  84                 data->ts_falling = now;
  85                 complete(&data->falling);
  86         }
  87
  88         return IRQ_HANDLED;
  89 }
  90
  91 static int ping_read(struct iio_dev *indio_dev)
  92 {
  93         struct ping_data *data = iio_priv(indio_dev);
  94         int ret;
  95         ktime_t ktime_dt;
  96         s64 dt_ns;
  97         u32 time_ns, distance_mm;
  98         struct platform_device *pdev = to_platform_device(data->dev);
  99
 100         /*
 101          * just one read-echo-cycle can take place at a time
 102          * ==> lock against concurrent reading calls
 103          */
 104         mutex_lock(&data->lock);
 105
 106         reinit_completion(&data->rising);
 107         reinit_completion(&data->falling);
 108
 109         gpiod_set_value(data->gpiod_ping, 1);
 110         udelay(data->cfg->trigger_pulse_us);
 111         gpiod_set_value(data->gpiod_ping, 0);
 112
 113         ret = gpiod_direction_input(data->gpiod_ping);
 114         if (ret < 0) {
 115                 mutex_unlock(&data->lock);
 116                 return ret;
 117         }
 118
 119         data->irqnr = gpiod_to_irq(data->gpiod_ping);
 120         if (data->irqnr < 0) {
 121                 dev_err(data->dev, "gpiod_to_irq: %d\n", data->irqnr);
 122                 mutex_unlock(&data->lock);
 123                 return data->irqnr;
 124         }
 125
 126         ret = request_irq(data->irqnr, ping_handle_irq,
 127                                 IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
 128                                                         pdev->name, indio_dev);
 129         if (ret < 0) {
 130                 dev_err(data->dev, "request_irq: %d\n", ret);
 131                 mutex_unlock(&data->lock);
 132                 return ret;
 133         }
 134
 135         /* it should not take more than 20 ms until echo is rising */
 136         ret = wait_for_completion_killable_timeout(&data->rising, HZ/50);
 137         if (ret < 0)
 138                 goto err_reset_direction;
 139         else if (ret == 0) {
 140                 ret = -ETIMEDOUT;
 141                 goto err_reset_direction;
 142         }
 143
 144         /* it cannot take more than 50 ms until echo is falling */
 145         ret = wait_for_completion_killable_timeout(&data->falling, HZ/20);
 146         if (ret < 0)
 147                 goto err_reset_direction;
 148         else if (ret == 0) {
 149                 ret = -ETIMEDOUT;
 150                 goto err_reset_direction;
 151         }
 152
 153         ktime_dt = ktime_sub(data->ts_falling, data->ts_rising);
 154
 155         free_irq(data->irqnr, indio_dev);
 156
 157         ret = gpiod_direction_output(data->gpiod_ping, GPIOD_OUT_LOW);
 158         if (ret < 0) {
 159                 mutex_unlock(&data->lock);
 160                 return ret;
 161         }
 162
 163         mutex_unlock(&data->lock);
 164
 165         dt_ns = ktime_to_ns(ktime_dt);
 166         if (dt_ns > data->cfg->timeout_ns) {
 167                 dev_dbg(data->dev, "distance out of range: dt=%lldns\n",
 168                                                                 dt_ns);
 169                 return -EIO;
 170         }
 171
 172         time_ns = dt_ns;
 173
 174         /*
 175          * read error code of laser ping sensor and give users chance to
 176          * figure out error by using dynamic debugging
 177          */
 178         if (data->cfg->laserping_error) {
 179                 if ((time_ns > 12500000) && (time_ns <= 13500000)) {
 180                         dev_dbg(data->dev, "target too close or to far\n");
 181                         return -EIO;
 182                 }
 183                 if ((time_ns > 13500000) && (time_ns <= 14500000)) {
 184                         dev_dbg(data->dev, "internal sensor error\n");
 185                         return -EIO;
 186                 }
 187                 if ((time_ns > 14500000) && (time_ns <= 15500000)) {
 188                         dev_dbg(data->dev, "internal sensor timeout\n");
 189                         return -EIO;
 190                 }
 191         }
 192
 193         /*
 194          * the speed as function of the temperature is approximately:
 195          *
 196          * speed = 331,5 + 0,6 * Temp
 197          *   with Temp in °C
 198          *   and speed in m/s
 199          *
 200          * use 343,5 m/s as ultrasonic speed at 20 °C here in absence of the
 201          * temperature
 202          *
 203          * therefore:
 204          *             time     343,5     time * 232
 205          * distance = ------ * ------- = ------------
 206          *             10^6         2        1350800
 207          *   with time in ns
 208          *   and distance in mm (one way)
 209          *
 210          * because we limit to 3 meters the multiplication with 232 just
 211          * fits into 32 bit
 212          */
 213         distance_mm = time_ns * 232 / 1350800;
 214
 215         return distance_mm;
 216
 217 err_reset_direction:
 218         free_irq(data->irqnr, indio_dev);
 219         mutex_unlock(&data->lock);
 220
 221         if (gpiod_direction_output(data->gpiod_ping, GPIOD_OUT_LOW))
 222                 dev_dbg(data->dev, "error in gpiod_direction_output\n");
 223         return ret;
 224 }
 225
 226 static int ping_read_raw(struct iio_dev *indio_dev,
 227                             struct iio_chan_spec const *channel, int *val,
 228                             int *val2, long info)
 229 {
 230         int ret;
 231
 232         if (channel->type != IIO_DISTANCE)
 233                 return -EINVAL;
 234
 235         switch (info) {
 236         case IIO_CHAN_INFO_RAW:
 237                 ret = ping_read(indio_dev);
 238                 if (ret < 0)
 239                         return ret;
 240                 *val = ret;
 241                 return IIO_VAL_INT;
 242         case IIO_CHAN_INFO_SCALE:
 243                 /*
 244                  * maximum resolution in datasheet is 1 mm
 245                  * 1 LSB is 1 mm
 246                  */
 247                 *val = 0;
 248                 *val2 = 1000;
 249                 return IIO_VAL_INT_PLUS_MICRO;
 250         default:
 251                 return -EINVAL;
 252         }
 253 }
 254
 255 static const struct iio_info ping_iio_info = {
 256         .read_raw               = ping_read_raw,
 257 };
 258
 259 static const struct iio_chan_spec ping_chan_spec[] = {
 260         {
 261                 .type = IIO_DISTANCE,
 262                 .info_mask_separate =
 263                                 BIT(IIO_CHAN_INFO_RAW) |
 264                                 BIT(IIO_CHAN_INFO_SCALE),
 265         },
 266 };
 267
 268 static const struct of_device_id of_ping_match[] = {
 269         { .compatible = "parallax,ping", .data = &pa_ping_cfg },
 270         { .compatible = "parallax,laserping", .data = &pa_laser_ping_cfg },
 271         {},
 272 };
 273
 274 MODULE_DEVICE_TABLE(of, of_ping_match);
 275
 276 static int ping_probe(struct platform_device *pdev)
 277 {
 278         struct device *dev = &pdev->dev;
 279         struct ping_data *data;
 280         struct iio_dev *indio_dev;
 281
 282         indio_dev = devm_iio_device_alloc(dev, sizeof(struct ping_data));
 283         if (!indio_dev) {
 284                 dev_err(dev, "failed to allocate IIO device\n");
 285                 return -ENOMEM;
 286         }
 287
 288         data = iio_priv(indio_dev);
 289         data->dev = dev;
 290         data->cfg = device_get_match_data(dev);
 291
 292         mutex_init(&data->lock);
 293         init_completion(&data->rising);
 294         init_completion(&data->falling);
 295
 296         data->gpiod_ping = devm_gpiod_get(dev, "ping", GPIOD_OUT_LOW);
 297         if (IS_ERR(data->gpiod_ping)) {
 298                 dev_err(dev, "failed to get ping-gpios: err=%ld\n",
 299                                                 PTR_ERR(data->gpiod_ping));
 300                 return PTR_ERR(data->gpiod_ping);
 301         }
 302
 303         if (gpiod_cansleep(data->gpiod_ping)) {
 304                 dev_err(data->dev, "cansleep-GPIOs not supported\n");
 305                 return -ENODEV;
 306         }
 307
 308         platform_set_drvdata(pdev, indio_dev);
 309
 310         indio_dev->name = "ping";
 311         indio_dev->info = &ping_iio_info;
 312         indio_dev->modes = INDIO_DIRECT_MODE;
 313         indio_dev->channels = ping_chan_spec;
 314         indio_dev->num_channels = ARRAY_SIZE(ping_chan_spec);
 315
 316         return devm_iio_device_register(dev, indio_dev);
 317 }
 318
 319 static struct platform_driver ping_driver = {
 320         .probe          = ping_probe,
 321         .driver         = {
 322                 .name           = "ping-gpio",
 323                 .of_match_table = of_ping_match,
 324         },
 325 };
 326
 327 module_platform_driver(ping_driver);
 328
 329 MODULE_AUTHOR("Andreas Klinger <ak@it-klinger.de>");
 330 MODULE_DESCRIPTION("PING sensors for distance measuring using one GPIOs");
 331 MODULE_LICENSE("GPL");
 332 MODULE_ALIAS("platform:ping");