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/init.h>
  20 #include <linux/interrupt.h>
  21 #include <linux/input.h>
  22 #include <linux/device.h>
  23 #include <linux/platform_device.h>
  24 #include <linux/gpio.h>
  25 #include <linux/rotary_encoder.h>
  26 #include <linux/slab.h>
  27 #include <linux/of.h>
  28 #include <linux/of_platform.h>
  29 #include <linux/of_gpio.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 #ifdef CONFIG_OF
 147 static struct of_device_id rotary_encoder_of_match[] = {
 148         { .compatible = "rotary-encoder", },
 149         { },
 150 };
 151 MODULE_DEVICE_TABLE(of, rotary_encoder_of_match);
 152
 153 static struct rotary_encoder_platform_data *rotary_encoder_parse_dt(struct device *dev)
 154 {
 155         const struct of_device_id *of_id =
 156                                 of_match_device(rotary_encoder_of_match, dev);
 157         struct device_node *np = dev->of_node;
 158         struct rotary_encoder_platform_data *pdata;
 159         enum of_gpio_flags flags;
 160
 161         if (!of_id || !np)
 162                 return NULL;
 163
 164         pdata = kzalloc(sizeof(struct rotary_encoder_platform_data),
 165                         GFP_KERNEL);
 166         if (!pdata)
 167                 return ERR_PTR(-ENOMEM);
 168
 169         of_property_read_u32(np, "rotary-encoder,steps", &pdata->steps);
 170         of_property_read_u32(np, "linux,axis", &pdata->axis);
 171
 172         pdata->gpio_a = of_get_gpio_flags(np, 0, &flags);
 173         pdata->inverted_a = flags & OF_GPIO_ACTIVE_LOW;
 174
 175         pdata->gpio_b = of_get_gpio_flags(np, 1, &flags);
 176         pdata->inverted_b = flags & OF_GPIO_ACTIVE_LOW;
 177
 178         pdata->relative_axis = !!of_get_property(np,
 179                                         "rotary-encoder,relative-axis", NULL);
 180         pdata->rollover = !!of_get_property(np,
 181                                         "rotary-encoder,rollover", NULL);
 182         pdata->half_period = !!of_get_property(np,
 183                                         "rotary-encoder,half-period", NULL);
 184
 185         return pdata;
 186 }
 187 #else
 188 static inline struct rotary_encoder_platform_data *
 189 rotary_encoder_parse_dt(struct device *dev)
 190 {
 191         return NULL;
 192 }
 193 #endif
 194
 195 static int rotary_encoder_probe(struct platform_device *pdev)
 196 {
 197         struct device *dev = &pdev->dev;
 198         const struct rotary_encoder_platform_data *pdata = dev_get_platdata(dev);
 199         struct rotary_encoder *encoder;
 200         struct input_dev *input;
 201         irq_handler_t handler;
 202         int err;
 203
 204         if (!pdata) {
 205                 pdata = rotary_encoder_parse_dt(dev);
 206                 if (IS_ERR(pdata))
 207                         return PTR_ERR(pdata);
 208
 209                 if (!pdata) {
 210                         dev_err(dev, "missing platform data\n");
 211                         return -EINVAL;
 212                 }
 213         }
 214
 215         encoder = kzalloc(sizeof(struct rotary_encoder), GFP_KERNEL);
 216         input = input_allocate_device();
 217         if (!encoder || !input) {
 218                 err = -ENOMEM;
 219                 goto exit_free_mem;
 220         }
 221
 222         encoder->input = input;
 223         encoder->pdata = pdata;
 224
 225         input->name = pdev->name;
 226         input->id.bustype = BUS_HOST;
 227         input->dev.parent = dev;
 228
 229         if (pdata->relative_axis) {
 230                 input->evbit[0] = BIT_MASK(EV_REL);
 231                 input->relbit[0] = BIT_MASK(pdata->axis);
 232         } else {
 233                 input->evbit[0] = BIT_MASK(EV_ABS);
 234                 input_set_abs_params(encoder->input,
 235                                      pdata->axis, 0, pdata->steps, 0, 1);
 236         }
 237
 238         /* request the GPIOs */
 239         err = gpio_request_one(pdata->gpio_a, GPIOF_IN, dev_name(dev));
 240         if (err) {
 241                 dev_err(dev, "unable to request GPIO %d\n", pdata->gpio_a);
 242                 goto exit_free_mem;
 243         }
 244
 245         err = gpio_request_one(pdata->gpio_b, GPIOF_IN, dev_name(dev));
 246         if (err) {
 247                 dev_err(dev, "unable to request GPIO %d\n", pdata->gpio_b);
 248                 goto exit_free_gpio_a;
 249         }
 250
 251         encoder->irq_a = gpio_to_irq(pdata->gpio_a);
 252         encoder->irq_b = gpio_to_irq(pdata->gpio_b);
 253
 254         /* request the IRQs */
 255         if (pdata->half_period) {
 256                 handler = &rotary_encoder_half_period_irq;
 257                 encoder->last_stable = rotary_encoder_get_state(pdata);
 258         } else {
 259                 handler = &rotary_encoder_irq;
 260         }
 261
 262         err = request_irq(encoder->irq_a, handler,
 263                           IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
 264                           DRV_NAME, encoder);
 265         if (err) {
 266                 dev_err(dev, "unable to request IRQ %d\n", encoder->irq_a);
 267                 goto exit_free_gpio_b;
 268         }
 269
 270         err = request_irq(encoder->irq_b, handler,
 271                           IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
 272                           DRV_NAME, encoder);
 273         if (err) {
 274                 dev_err(dev, "unable to request IRQ %d\n", encoder->irq_b);
 275                 goto exit_free_irq_a;
 276         }
 277
 278         err = input_register_device(input);
 279         if (err) {
 280                 dev_err(dev, "failed to register input device\n");
 281                 goto exit_free_irq_b;
 282         }
 283
 284         platform_set_drvdata(pdev, encoder);
 285
 286         return 0;
 287
 288 exit_free_irq_b:
 289         free_irq(encoder->irq_b, encoder);
 290 exit_free_irq_a:
 291         free_irq(encoder->irq_a, encoder);
 292 exit_free_gpio_b:
 293         gpio_free(pdata->gpio_b);
 294 exit_free_gpio_a:
 295         gpio_free(pdata->gpio_a);
 296 exit_free_mem:
 297         input_free_device(input);
 298         kfree(encoder);
 299         if (!dev_get_platdata(&pdev->dev))
 300                 kfree(pdata);
 301
 302         return err;
 303 }
 304
 305 static int rotary_encoder_remove(struct platform_device *pdev)
 306 {
 307         struct rotary_encoder *encoder = platform_get_drvdata(pdev);
 308         const struct rotary_encoder_platform_data *pdata = encoder->pdata;
 309
 310         free_irq(encoder->irq_a, encoder);
 311         free_irq(encoder->irq_b, encoder);
 312         gpio_free(pdata->gpio_a);
 313         gpio_free(pdata->gpio_b);
 314
 315         input_unregister_device(encoder->input);
 316         kfree(encoder);
 317
 318         if (!dev_get_platdata(&pdev->dev))
 319                 kfree(pdata);
 320
 321         return 0;
 322 }
 323
 324 static struct platform_driver rotary_encoder_driver = {
 325         .probe          = rotary_encoder_probe,
 326         .remove         = rotary_encoder_remove,
 327         .driver         = {
 328                 .name   = DRV_NAME,
 329                 .owner  = THIS_MODULE,
 330                 .of_match_table = of_match_ptr(rotary_encoder_of_match),
 331         }
 332 };
 333 module_platform_driver(rotary_encoder_driver);
 334
 335 MODULE_ALIAS("platform:" DRV_NAME);
 336 MODULE_DESCRIPTION("GPIO rotary encoder driver");
 337 MODULE_AUTHOR("Daniel Mack <daniel@caiaq.de>, Johan Hovold");
 338 MODULE_LICENSE("GPL v2");