drivers/input/misc/rotary_encoder.c

   1 /*
   2  * rotary_encoder.c
   3  *
   4  * (c) 2009 Daniel Mack <daniel@caiaq.de>
   5  * Copyright (C) 2011 Johan Hovold <jhovold@gmail.com>
   6  *
   7  * state machine code inspired by code from Tim Ruetz
   8  *
   9  * A generic driver for rotary encoders connected to GPIO lines.
  10  * See file:Documentation/input/rotary-encoder.txt for more information
  11  *
  12  * This program is free software; you can redistribute it and/or modify
  13  * it under the terms of the GNU General Public License version 2 as
  14  * published by the Free Software Foundation.
  15  */
  16
  17 #include <linux/kernel.h>
  18 #include <linux/module.h>
  19 #include <linux/interrupt.h>
  20 #include <linux/input.h>
  21 #include <linux/device.h>
  22 #include <linux/platform_device.h>
  23 #include <linux/gpio/consumer.h>
  24 #include <linux/slab.h>
  25 #include <linux/of.h>
  26 #include <linux/pm.h>
  27 #include <linux/property.h>
  28
  29 #define DRV_NAME "rotary-encoder"
  30
  31 struct rotary_encoder {
  32         struct input_dev *input;
  33
  34         struct mutex access_mutex;
  35
  36         u32 steps;
  37         u32 axis;
  38         bool relative_axis;
  39         bool rollover;
  40
  41         unsigned int pos;
  42
  43         struct gpio_descs *gpios;
  44
  45         unsigned int *irq;
  46
  47         bool armed;
  48         signed char dir;        /* 1 - clockwise, -1 - CCW */
  49
  50         unsigned last_stable;
  51 };
  52
  53 static unsigned rotary_encoder_get_state(struct rotary_encoder *encoder)
  54 {
  55         int i;
  56         unsigned ret = 0;
  57
  58         for (i = 0; i < encoder->gpios->ndescs; ++i) {
  59                 int val = gpiod_get_value_cansleep(encoder->gpios->desc[i]);
  60                 /* convert from gray encoding to normal */
  61                 if (ret & 1)
  62                         val = !val;
  63
  64                 ret = ret << 1 | val;
  65         }
  66
  67         return ret & 3;
  68 }
  69
  70 static void rotary_encoder_report_event(struct rotary_encoder *encoder)
  71 {
  72         if (encoder->relative_axis) {
  73                 input_report_rel(encoder->input,
  74                                  encoder->axis, encoder->dir);
  75         } else {
  76                 unsigned int pos = encoder->pos;
  77
  78                 if (encoder->dir < 0) {
  79                         /* turning counter-clockwise */
  80                         if (encoder->rollover)
  81                                 pos += encoder->steps;
  82                         if (pos)
  83                                 pos--;
  84                 } else {
  85                         /* turning clockwise */
  86                         if (encoder->rollover || pos < encoder->steps)
  87                                 pos++;
  88                 }
  89
  90                 if (encoder->rollover)
  91                         pos %= encoder->steps;
  92
  93                 encoder->pos = pos;
  94                 input_report_abs(encoder->input, encoder->axis, encoder->pos);
  95         }
  96
  97         input_sync(encoder->input);
  98 }
  99
 100 static irqreturn_t rotary_encoder_irq(int irq, void *dev_id)
 101 {
 102         struct rotary_encoder *encoder = dev_id;
 103         unsigned state;
 104
 105         mutex_lock(&encoder->access_mutex);
 106
 107         state = rotary_encoder_get_state(encoder);
 108
 109         switch (state) {
 110         case 0x0:
 111                 if (encoder->armed) {
 112                         rotary_encoder_report_event(encoder);
 113                         encoder->armed = false;
 114                 }
 115                 break;
 116
 117         case 0x1:
 118         case 0x3:
 119                 if (encoder->armed)
 120                         encoder->dir = 2 - state;
 121                 break;
 122
 123         case 0x2:
 124                 encoder->armed = true;
 125                 break;
 126         }
 127
 128         mutex_unlock(&encoder->access_mutex);
 129
 130         return IRQ_HANDLED;
 131 }
 132
 133 static irqreturn_t rotary_encoder_half_period_irq(int irq, void *dev_id)
 134 {
 135         struct rotary_encoder *encoder = dev_id;
 136         unsigned int state;
 137
 138         mutex_lock(&encoder->access_mutex);
 139
 140         state = rotary_encoder_get_state(encoder);
 141
 142         if (state & 1) {
 143                 encoder->dir = ((encoder->last_stable - state + 1) % 4) - 1;
 144         } else {
 145                 if (state != encoder->last_stable) {
 146                         rotary_encoder_report_event(encoder);
 147                         encoder->last_stable = state;
 148                 }
 149         }
 150
 151         mutex_unlock(&encoder->access_mutex);
 152
 153         return IRQ_HANDLED;
 154 }
 155
 156 static irqreturn_t rotary_encoder_quarter_period_irq(int irq, void *dev_id)
 157 {
 158         struct rotary_encoder *encoder = dev_id;
 159         unsigned int state;
 160
 161         mutex_lock(&encoder->access_mutex);
 162
 163         state = rotary_encoder_get_state(encoder);
 164
 165         if ((encoder->last_stable + 1) % 4 == state)
 166                 encoder->dir = 1;
 167         else if (encoder->last_stable == (state + 1) % 4)
 168                 encoder->dir = -1;
 169         else
 170                 goto out;
 171
 172         rotary_encoder_report_event(encoder);
 173
 174 out:
 175         encoder->last_stable = state;
 176         mutex_unlock(&encoder->access_mutex);
 177
 178         return IRQ_HANDLED;
 179 }
 180
 181 static int rotary_encoder_probe(struct platform_device *pdev)
 182 {
 183         struct device *dev = &pdev->dev;
 184         struct rotary_encoder *encoder;
 185         struct input_dev *input;
 186         irq_handler_t handler;
 187         u32 steps_per_period;
 188         unsigned int i;
 189         int err;
 190
 191         encoder = devm_kzalloc(dev, sizeof(struct rotary_encoder), GFP_KERNEL);
 192         if (!encoder)
 193                 return -ENOMEM;
 194
 195         mutex_init(&encoder->access_mutex);
 196
 197         device_property_read_u32(dev, "rotary-encoder,steps", &encoder->steps);
 198
 199         err = device_property_read_u32(dev, "rotary-encoder,steps-per-period",
 200                                        &steps_per_period);
 201         if (err) {
 202                 /*
 203                  * The 'half-period' property has been deprecated, you must
 204                  * use 'steps-per-period' and set an appropriate value, but
 205                  * we still need to parse it to maintain compatibility. If
 206                  * neither property is present we fall back to the one step
 207                  * per period behavior.
 208                  */
 209                 steps_per_period = device_property_read_bool(dev,
 210                                         "rotary-encoder,half-period") ? 2 : 1;
 211         }
 212
 213         encoder->rollover =
 214                 device_property_read_bool(dev, "rotary-encoder,rollover");
 215
 216         device_property_read_u32(dev, "linux,axis", &encoder->axis);
 217         encoder->relative_axis =
 218                 device_property_read_bool(dev, "rotary-encoder,relative-axis");
 219
 220         encoder->gpios = devm_gpiod_get_array(dev, NULL, GPIOD_IN);
 221         if (IS_ERR(encoder->gpios)) {
 222                 dev_err(dev, "unable to get gpios\n");
 223                 return PTR_ERR(encoder->gpios);
 224         }
 225         if (encoder->gpios->ndescs < 2) {
 226                 dev_err(dev, "not enough gpios found\n");
 227                 return -EINVAL;
 228         }
 229
 230         input = devm_input_allocate_device(dev);
 231         if (!input)
 232                 return -ENOMEM;
 233
 234         encoder->input = input;
 235
 236         input->name = pdev->name;
 237         input->id.bustype = BUS_HOST;
 238         input->dev.parent = dev;
 239
 240         if (encoder->relative_axis)
 241                 input_set_capability(input, EV_REL, encoder->axis);
 242         else
 243                 input_set_abs_params(input,
 244                                      encoder->axis, 0, encoder->steps, 0, 1);
 245
 246         switch (steps_per_period >> (encoder->gpios->ndescs - 2)) {
 247         case 4:
 248                 handler = &rotary_encoder_quarter_period_irq;
 249                 encoder->last_stable = rotary_encoder_get_state(encoder);
 250                 break;
 251         case 2:
 252                 handler = &rotary_encoder_half_period_irq;
 253                 encoder->last_stable = rotary_encoder_get_state(encoder);
 254                 break;
 255         case 1:
 256                 handler = &rotary_encoder_irq;
 257                 break;
 258         default:
 259                 dev_err(dev, "'%d' is not a valid steps-per-period value\n",
 260                         steps_per_period);
 261                 return -EINVAL;
 262         }
 263
 264         encoder->irq =
 265                 devm_kzalloc(dev,
 266                              sizeof(*encoder->irq) * encoder->gpios->ndescs,
 267                              GFP_KERNEL);
 268         if (!encoder->irq)
 269                 return -ENOMEM;
 270
 271         for (i = 0; i < encoder->gpios->ndescs; ++i) {
 272                 encoder->irq[i] = gpiod_to_irq(encoder->gpios->desc[i]);
 273
 274                 err = devm_request_threaded_irq(dev, encoder->irq[i],
 275                                 NULL, handler,
 276                                 IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING |
 277                                 IRQF_ONESHOT,
 278                                 DRV_NAME, encoder);
 279                 if (err) {
 280                         dev_err(dev, "unable to request IRQ %d (gpio#%d)\n",
 281                                 encoder->irq[i], i);
 282                         return err;
 283                 }
 284         }
 285
 286         err = input_register_device(input);
 287         if (err) {
 288                 dev_err(dev, "failed to register input device\n");
 289                 return err;
 290         }
 291
 292         device_init_wakeup(dev,
 293                            device_property_read_bool(dev, "wakeup-source"));
 294
 295         platform_set_drvdata(pdev, encoder);
 296
 297         return 0;
 298 }
 299
 300 static int __maybe_unused rotary_encoder_suspend(struct device *dev)
 301 {
 302         struct rotary_encoder *encoder = dev_get_drvdata(dev);
 303         unsigned int i;
 304
 305         if (device_may_wakeup(dev)) {
 306                 for (i = 0; i < encoder->gpios->ndescs; ++i)
 307                         enable_irq_wake(encoder->irq[i]);
 308         }
 309
 310         return 0;
 311 }
 312
 313 static int __maybe_unused rotary_encoder_resume(struct device *dev)
 314 {
 315         struct rotary_encoder *encoder = dev_get_drvdata(dev);
 316         unsigned int i;
 317
 318         if (device_may_wakeup(dev)) {
 319                 for (i = 0; i < encoder->gpios->ndescs; ++i)
 320                         disable_irq_wake(encoder->irq[i]);
 321         }
 322
 323         return 0;
 324 }
 325
 326 static SIMPLE_DEV_PM_OPS(rotary_encoder_pm_ops,
 327                          rotary_encoder_suspend, rotary_encoder_resume);
 328
 329 #ifdef CONFIG_OF
 330 static const struct of_device_id rotary_encoder_of_match[] = {
 331         { .compatible = "rotary-encoder", },
 332         { },
 333 };
 334 MODULE_DEVICE_TABLE(of, rotary_encoder_of_match);
 335 #endif
 336
 337 static struct platform_driver rotary_encoder_driver = {
 338         .probe          = rotary_encoder_probe,
 339         .driver         = {
 340                 .name   = DRV_NAME,
 341                 .pm     = &rotary_encoder_pm_ops,
 342                 .of_match_table = of_match_ptr(rotary_encoder_of_match),
 343         }
 344 };
 345 module_platform_driver(rotary_encoder_driver);
 346
 347 MODULE_ALIAS("platform:" DRV_NAME);
 348 MODULE_DESCRIPTION("GPIO rotary encoder driver");
 349 MODULE_AUTHOR("Daniel Mack <daniel@caiaq.de>, Johan Hovold");
 350 MODULE_LICENSE("GPL v2");