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.h>
  24 #include <linux/rotary_encoder.h>
  25 #include <linux/slab.h>
  26 #include <linux/of.h>
  27 #include <linux/of_platform.h>
  28 #include <linux/of_gpio.h>
  29 #include <linux/pm.h>
  30
  31 #define DRV_NAME "rotary-encoder"
  32
  33 struct rotary_encoder {
  34         struct input_dev *input;
  35         const struct rotary_encoder_platform_data *pdata;
  36
  37         unsigned int axis;
  38         unsigned int pos;
  39
  40         unsigned int irq_a;
  41         unsigned int irq_b;
  42
  43         bool armed;
  44         unsigned char dir;      /* 0 - clockwise, 1 - CCW */
  45
  46         char last_stable;
  47 };
  48
  49 static int rotary_encoder_get_state(const struct rotary_encoder_platform_data *pdata)
  50 {
  51         int a = !!gpio_get_value(pdata->gpio_a);
  52         int b = !!gpio_get_value(pdata->gpio_b);
  53
  54         a ^= pdata->inverted_a;
  55         b ^= pdata->inverted_b;
  56
  57         return ((a << 1) | b);
  58 }
  59
  60 static void rotary_encoder_report_event(struct rotary_encoder *encoder)
  61 {
  62         const struct rotary_encoder_platform_data *pdata = encoder->pdata;
  63
  64         if (pdata->relative_axis) {
  65                 input_report_rel(encoder->input,
  66                                  pdata->axis, encoder->dir ? -1 : 1);
  67         } else {
  68                 unsigned int pos = encoder->pos;
  69
  70                 if (encoder->dir) {
  71                         /* turning counter-clockwise */
  72                         if (pdata->rollover)
  73                                 pos += pdata->steps;
  74                         if (pos)
  75                                 pos--;
  76                 } else {
  77                         /* turning clockwise */
  78                         if (pdata->rollover || pos < pdata->steps)
  79                                 pos++;
  80                 }
  81
  82                 if (pdata->rollover)
  83                         pos %= pdata->steps;
  84
  85                 encoder->pos = pos;
  86                 input_report_abs(encoder->input, pdata->axis, encoder->pos);
  87         }
  88
  89         input_sync(encoder->input);
  90 }
  91
  92 static irqreturn_t rotary_encoder_irq(int irq, void *dev_id)
  93 {
  94         struct rotary_encoder *encoder = dev_id;
  95         int state;
  96
  97         state = rotary_encoder_get_state(encoder->pdata);
  98
  99         switch (state) {
 100         case 0x0:
 101                 if (encoder->armed) {
 102                         rotary_encoder_report_event(encoder);
 103                         encoder->armed = false;
 104                 }
 105                 break;
 106
 107         case 0x1:
 108         case 0x2:
 109                 if (encoder->armed)
 110                         encoder->dir = state - 1;
 111                 break;
 112
 113         case 0x3:
 114                 encoder->armed = true;
 115                 break;
 116         }
 117
 118         return IRQ_HANDLED;
 119 }
 120
 121 static irqreturn_t rotary_encoder_half_period_irq(int irq, void *dev_id)
 122 {
 123         struct rotary_encoder *encoder = dev_id;
 124         int state;
 125
 126         state = rotary_encoder_get_state(encoder->pdata);
 127
 128         switch (state) {
 129         case 0x00:
 130         case 0x03:
 131                 if (state != encoder->last_stable) {
 132                         rotary_encoder_report_event(encoder);
 133                         encoder->last_stable = state;
 134                 }
 135                 break;
 136
 137         case 0x01:
 138         case 0x02:
 139                 encoder->dir = (encoder->last_stable + state) & 0x01;
 140                 break;
 141         }
 142
 143         return IRQ_HANDLED;
 144 }
 145
 146 static irqreturn_t rotary_encoder_quarter_period_irq(int irq, void *dev_id)
 147 {
 148         struct rotary_encoder *encoder = dev_id;
 149         unsigned char sum;
 150         int state;
 151
 152         state = rotary_encoder_get_state(encoder->pdata);
 153
 154         /*
 155          * We encode the previous and the current state using a byte.
 156          * The previous state in the MSB nibble, the current state in the LSB
 157          * nibble. Then use a table to decide the direction of the turn.
 158          */
 159         sum = (encoder->last_stable << 4) + state;
 160         switch (sum) {
 161         case 0x31:
 162         case 0x10:
 163         case 0x02:
 164         case 0x23:
 165                 encoder->dir = 0; /* clockwise */
 166                 break;
 167
 168         case 0x13:
 169         case 0x01:
 170         case 0x20:
 171         case 0x32:
 172                 encoder->dir = 1; /* counter-clockwise */
 173                 break;
 174
 175         default:
 176                 /*
 177                  * Ignore all other values. This covers the case when the
 178                  * state didn't change (a spurious interrupt) and the
 179                  * cases where the state changed by two steps, making it
 180                  * impossible to tell the direction.
 181                  *
 182                  * In either case, don't report any event and save the
 183                  * state for later.
 184                  */
 185                 goto out;
 186         }
 187
 188         rotary_encoder_report_event(encoder);
 189
 190 out:
 191         encoder->last_stable = state;
 192         return IRQ_HANDLED;
 193 }
 194
 195 #ifdef CONFIG_OF
 196 static const struct of_device_id rotary_encoder_of_match[] = {
 197         { .compatible = "rotary-encoder", },
 198         { },
 199 };
 200 MODULE_DEVICE_TABLE(of, rotary_encoder_of_match);
 201
 202 static struct rotary_encoder_platform_data *rotary_encoder_parse_dt(struct device *dev)
 203 {
 204         const struct of_device_id *of_id =
 205                                 of_match_device(rotary_encoder_of_match, dev);
 206         struct device_node *np = dev->of_node;
 207         struct rotary_encoder_platform_data *pdata;
 208         enum of_gpio_flags flags;
 209         int error;
 210
 211         if (!of_id || !np)
 212                 return NULL;
 213
 214         pdata = kzalloc(sizeof(struct rotary_encoder_platform_data),
 215                         GFP_KERNEL);
 216         if (!pdata)
 217                 return ERR_PTR(-ENOMEM);
 218
 219         of_property_read_u32(np, "rotary-encoder,steps", &pdata->steps);
 220         of_property_read_u32(np, "linux,axis", &pdata->axis);
 221
 222         pdata->gpio_a = of_get_gpio_flags(np, 0, &flags);
 223         pdata->inverted_a = flags & OF_GPIO_ACTIVE_LOW;
 224
 225         pdata->gpio_b = of_get_gpio_flags(np, 1, &flags);
 226         pdata->inverted_b = flags & OF_GPIO_ACTIVE_LOW;
 227
 228         pdata->relative_axis =
 229                 of_property_read_bool(np, "rotary-encoder,relative-axis");
 230         pdata->rollover = of_property_read_bool(np, "rotary-encoder,rollover");
 231
 232         error = of_property_read_u32(np, "rotary-encoder,steps-per-period",
 233                                      &pdata->steps_per_period);
 234         if (error) {
 235                 /*
 236                  * The 'half-period' property has been deprecated, you must use
 237                  * 'steps-per-period' and set an appropriate value, but we still
 238                  * need to parse it to maintain compatibility.
 239                  */
 240                 if (of_property_read_bool(np, "rotary-encoder,half-period")) {
 241                         pdata->steps_per_period = 2;
 242                 } else {
 243                         /* Fallback to one step per period behavior */
 244                         pdata->steps_per_period = 1;
 245                 }
 246         }
 247
 248         pdata->wakeup_source = of_property_read_bool(np, "wakeup-source");
 249
 250         return pdata;
 251 }
 252 #else
 253 static inline struct rotary_encoder_platform_data *
 254 rotary_encoder_parse_dt(struct device *dev)
 255 {
 256         return NULL;
 257 }
 258 #endif
 259
 260 static int rotary_encoder_probe(struct platform_device *pdev)
 261 {
 262         struct device *dev = &pdev->dev;
 263         const struct rotary_encoder_platform_data *pdata = dev_get_platdata(dev);
 264         struct rotary_encoder *encoder;
 265         struct input_dev *input;
 266         irq_handler_t handler;
 267         int err;
 268
 269         if (!pdata) {
 270                 pdata = rotary_encoder_parse_dt(dev);
 271                 if (IS_ERR(pdata))
 272                         return PTR_ERR(pdata);
 273
 274                 if (!pdata) {
 275                         dev_err(dev, "missing platform data\n");
 276                         return -EINVAL;
 277                 }
 278         }
 279
 280         encoder = kzalloc(sizeof(struct rotary_encoder), GFP_KERNEL);
 281         input = input_allocate_device();
 282         if (!encoder || !input) {
 283                 err = -ENOMEM;
 284                 goto exit_free_mem;
 285         }
 286
 287         encoder->input = input;
 288         encoder->pdata = pdata;
 289
 290         input->name = pdev->name;
 291         input->id.bustype = BUS_HOST;
 292         input->dev.parent = dev;
 293
 294         if (pdata->relative_axis) {
 295                 input->evbit[0] = BIT_MASK(EV_REL);
 296                 input->relbit[0] = BIT_MASK(pdata->axis);
 297         } else {
 298                 input->evbit[0] = BIT_MASK(EV_ABS);
 299                 input_set_abs_params(encoder->input,
 300                                      pdata->axis, 0, pdata->steps, 0, 1);
 301         }
 302
 303         /* request the GPIOs */
 304         err = gpio_request_one(pdata->gpio_a, GPIOF_IN, dev_name(dev));
 305         if (err) {
 306                 dev_err(dev, "unable to request GPIO %d\n", pdata->gpio_a);
 307                 goto exit_free_mem;
 308         }
 309
 310         err = gpio_request_one(pdata->gpio_b, GPIOF_IN, dev_name(dev));
 311         if (err) {
 312                 dev_err(dev, "unable to request GPIO %d\n", pdata->gpio_b);
 313                 goto exit_free_gpio_a;
 314         }
 315
 316         encoder->irq_a = gpio_to_irq(pdata->gpio_a);
 317         encoder->irq_b = gpio_to_irq(pdata->gpio_b);
 318
 319         switch (pdata->steps_per_period) {
 320         case 4:
 321                 handler = &rotary_encoder_quarter_period_irq;
 322                 encoder->last_stable = rotary_encoder_get_state(pdata);
 323                 break;
 324         case 2:
 325                 handler = &rotary_encoder_half_period_irq;
 326                 encoder->last_stable = rotary_encoder_get_state(pdata);
 327                 break;
 328         case 1:
 329                 handler = &rotary_encoder_irq;
 330                 break;
 331         default:
 332                 dev_err(dev, "'%d' is not a valid steps-per-period value\n",
 333                         pdata->steps_per_period);
 334                 err = -EINVAL;
 335                 goto exit_free_gpio_b;
 336         }
 337
 338         err = request_irq(encoder->irq_a, handler,
 339                           IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
 340                           DRV_NAME, encoder);
 341         if (err) {
 342                 dev_err(dev, "unable to request IRQ %d\n", encoder->irq_a);
 343                 goto exit_free_gpio_b;
 344         }
 345
 346         err = request_irq(encoder->irq_b, handler,
 347                           IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
 348                           DRV_NAME, encoder);
 349         if (err) {
 350                 dev_err(dev, "unable to request IRQ %d\n", encoder->irq_b);
 351                 goto exit_free_irq_a;
 352         }
 353
 354         err = input_register_device(input);
 355         if (err) {
 356                 dev_err(dev, "failed to register input device\n");
 357                 goto exit_free_irq_b;
 358         }
 359
 360         device_init_wakeup(&pdev->dev, pdata->wakeup_source);
 361
 362         platform_set_drvdata(pdev, encoder);
 363
 364         return 0;
 365
 366 exit_free_irq_b:
 367         free_irq(encoder->irq_b, encoder);
 368 exit_free_irq_a:
 369         free_irq(encoder->irq_a, encoder);
 370 exit_free_gpio_b:
 371         gpio_free(pdata->gpio_b);
 372 exit_free_gpio_a:
 373         gpio_free(pdata->gpio_a);
 374 exit_free_mem:
 375         input_free_device(input);
 376         kfree(encoder);
 377         if (!dev_get_platdata(&pdev->dev))
 378                 kfree(pdata);
 379
 380         return err;
 381 }
 382
 383 static int rotary_encoder_remove(struct platform_device *pdev)
 384 {
 385         struct rotary_encoder *encoder = platform_get_drvdata(pdev);
 386         const struct rotary_encoder_platform_data *pdata = encoder->pdata;
 387
 388         device_init_wakeup(&pdev->dev, false);
 389
 390         free_irq(encoder->irq_a, encoder);
 391         free_irq(encoder->irq_b, encoder);
 392         gpio_free(pdata->gpio_a);
 393         gpio_free(pdata->gpio_b);
 394
 395         input_unregister_device(encoder->input);
 396         kfree(encoder);
 397
 398         if (!dev_get_platdata(&pdev->dev))
 399                 kfree(pdata);
 400
 401         return 0;
 402 }
 403
 404 #ifdef CONFIG_PM_SLEEP
 405 static int rotary_encoder_suspend(struct device *dev)
 406 {
 407         struct rotary_encoder *encoder = dev_get_drvdata(dev);
 408
 409         if (device_may_wakeup(dev)) {
 410                 enable_irq_wake(encoder->irq_a);
 411                 enable_irq_wake(encoder->irq_b);
 412         }
 413
 414         return 0;
 415 }
 416
 417 static int rotary_encoder_resume(struct device *dev)
 418 {
 419         struct rotary_encoder *encoder = dev_get_drvdata(dev);
 420
 421         if (device_may_wakeup(dev)) {
 422                 disable_irq_wake(encoder->irq_a);
 423                 disable_irq_wake(encoder->irq_b);
 424         }
 425
 426         return 0;
 427 }
 428 #endif
 429
 430 static SIMPLE_DEV_PM_OPS(rotary_encoder_pm_ops,
 431                  rotary_encoder_suspend, rotary_encoder_resume);
 432
 433 static struct platform_driver rotary_encoder_driver = {
 434         .probe          = rotary_encoder_probe,
 435         .remove         = rotary_encoder_remove,
 436         .driver         = {
 437                 .name   = DRV_NAME,
 438                 .pm     = &rotary_encoder_pm_ops,
 439                 .of_match_table = of_match_ptr(rotary_encoder_of_match),
 440         }
 441 };
 442 module_platform_driver(rotary_encoder_driver);
 443
 444 MODULE_ALIAS("platform:" DRV_NAME);
 445 MODULE_DESCRIPTION("GPIO rotary encoder driver");
 446 MODULE_AUTHOR("Daniel Mack <daniel@caiaq.de>, Johan Hovold");
 447 MODULE_LICENSE("GPL v2");