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_platform.h>
  28 #include <linux/of_gpio.h>
  29
  30 #define DRV_NAME "rotary-encoder"
  31
  32 struct rotary_encoder {
  33         struct input_dev *input;
  34         const struct rotary_encoder_platform_data *pdata;
  35
  36         unsigned int axis;
  37         unsigned int pos;
  38
  39         unsigned int irq_a;
  40         unsigned int irq_b;
  41
  42         bool armed;
  43         unsigned char dir;      /* 0 - clockwise, 1 - CCW */
  44
  45         char last_stable;
  46 };
  47
  48 static int rotary_encoder_get_state(const struct rotary_encoder_platform_data *pdata)
  49 {
  50         int a = !!gpio_get_value(pdata->gpio_a);
  51         int b = !!gpio_get_value(pdata->gpio_b);
  52
  53         a ^= pdata->inverted_a;
  54         b ^= pdata->inverted_b;
  55
  56         return ((a << 1) | b);
  57 }
  58
  59 static void rotary_encoder_report_event(struct rotary_encoder *encoder)
  60 {
  61         const struct rotary_encoder_platform_data *pdata = encoder->pdata;
  62
  63         if (pdata->relative_axis) {
  64                 input_report_rel(encoder->input,
  65                                  pdata->axis, encoder->dir ? -1 : 1);
  66         } else {
  67                 unsigned int pos = encoder->pos;
  68
  69                 if (encoder->dir) {
  70                         /* turning counter-clockwise */
  71                         if (pdata->rollover)
  72                                 pos += pdata->steps;
  73                         if (pos)
  74                                 pos--;
  75                 } else {
  76                         /* turning clockwise */
  77                         if (pdata->rollover || pos < pdata->steps)
  78                                 pos++;
  79                 }
  80
  81                 if (pdata->rollover)
  82                         pos %= pdata->steps;
  83
  84                 encoder->pos = pos;
  85                 input_report_abs(encoder->input, pdata->axis, encoder->pos);
  86         }
  87
  88         input_sync(encoder->input);
  89 }
  90
  91 static irqreturn_t rotary_encoder_irq(int irq, void *dev_id)
  92 {
  93         struct rotary_encoder *encoder = dev_id;
  94         int state;
  95
  96         state = rotary_encoder_get_state(encoder->pdata);
  97
  98         switch (state) {
  99         case 0x0:
 100                 if (encoder->armed) {
 101                         rotary_encoder_report_event(encoder);
 102                         encoder->armed = false;
 103                 }
 104                 break;
 105
 106         case 0x1:
 107         case 0x2:
 108                 if (encoder->armed)
 109                         encoder->dir = state - 1;
 110                 break;
 111
 112         case 0x3:
 113                 encoder->armed = true;
 114                 break;
 115         }
 116
 117         return IRQ_HANDLED;
 118 }
 119
 120 static irqreturn_t rotary_encoder_half_period_irq(int irq, void *dev_id)
 121 {
 122         struct rotary_encoder *encoder = dev_id;
 123         int state;
 124
 125         state = rotary_encoder_get_state(encoder->pdata);
 126
 127         switch (state) {
 128         case 0x00:
 129         case 0x03:
 130                 if (state != encoder->last_stable) {
 131                         rotary_encoder_report_event(encoder);
 132                         encoder->last_stable = state;
 133                 }
 134                 break;
 135
 136         case 0x01:
 137         case 0x02:
 138                 encoder->dir = (encoder->last_stable + state) & 0x01;
 139                 break;
 140         }
 141
 142         return IRQ_HANDLED;
 143 }
 144
 145 #ifdef CONFIG_OF
 146 static struct of_device_id rotary_encoder_of_match[] = {
 147         { .compatible = "rotary-encoder", },
 148         { },
 149 };
 150 MODULE_DEVICE_TABLE(of, rotary_encoder_of_match);
 151
 152 static struct rotary_encoder_platform_data *rotary_encoder_parse_dt(struct device *dev)
 153 {
 154         const struct of_device_id *of_id =
 155                                 of_match_device(rotary_encoder_of_match, dev);
 156         struct device_node *np = dev->of_node;
 157         struct rotary_encoder_platform_data *pdata;
 158         enum of_gpio_flags flags;
 159
 160         if (!of_id || !np)
 161                 return NULL;
 162
 163         pdata = kzalloc(sizeof(struct rotary_encoder_platform_data),
 164                         GFP_KERNEL);
 165         if (!pdata)
 166                 return ERR_PTR(-ENOMEM);
 167
 168         of_property_read_u32(np, "rotary-encoder,steps", &pdata->steps);
 169         of_property_read_u32(np, "linux,axis", &pdata->axis);
 170
 171         pdata->gpio_a = of_get_gpio_flags(np, 0, &flags);
 172         pdata->inverted_a = flags & OF_GPIO_ACTIVE_LOW;
 173
 174         pdata->gpio_b = of_get_gpio_flags(np, 1, &flags);
 175         pdata->inverted_b = flags & OF_GPIO_ACTIVE_LOW;
 176
 177         pdata->relative_axis = !!of_get_property(np,
 178                                         "rotary-encoder,relative-axis", NULL);
 179         pdata->rollover = !!of_get_property(np,
 180                                         "rotary-encoder,rollover", NULL);
 181         pdata->half_period = !!of_get_property(np,
 182                                         "rotary-encoder,half-period", NULL);
 183
 184         return pdata;
 185 }
 186 #else
 187 static inline struct rotary_encoder_platform_data *
 188 rotary_encoder_parse_dt(struct device *dev)
 189 {
 190         return NULL;
 191 }
 192 #endif
 193
 194 static int rotary_encoder_probe(struct platform_device *pdev)
 195 {
 196         struct device *dev = &pdev->dev;
 197         const struct rotary_encoder_platform_data *pdata = dev_get_platdata(dev);
 198         struct rotary_encoder *encoder;
 199         struct input_dev *input;
 200         irq_handler_t handler;
 201         int err;
 202
 203         if (!pdata) {
 204                 pdata = rotary_encoder_parse_dt(dev);
 205                 if (IS_ERR(pdata))
 206                         return PTR_ERR(pdata);
 207
 208                 if (!pdata) {
 209                         dev_err(dev, "missing platform data\n");
 210                         return -EINVAL;
 211                 }
 212         }
 213
 214         encoder = kzalloc(sizeof(struct rotary_encoder), GFP_KERNEL);
 215         input = input_allocate_device();
 216         if (!encoder || !input) {
 217                 err = -ENOMEM;
 218                 goto exit_free_mem;
 219         }
 220
 221         encoder->input = input;
 222         encoder->pdata = pdata;
 223
 224         input->name = pdev->name;
 225         input->id.bustype = BUS_HOST;
 226         input->dev.parent = dev;
 227
 228         if (pdata->relative_axis) {
 229                 input->evbit[0] = BIT_MASK(EV_REL);
 230                 input->relbit[0] = BIT_MASK(pdata->axis);
 231         } else {
 232                 input->evbit[0] = BIT_MASK(EV_ABS);
 233                 input_set_abs_params(encoder->input,
 234                                      pdata->axis, 0, pdata->steps, 0, 1);
 235         }
 236
 237         /* request the GPIOs */
 238         err = gpio_request_one(pdata->gpio_a, GPIOF_IN, dev_name(dev));
 239         if (err) {
 240                 dev_err(dev, "unable to request GPIO %d\n", pdata->gpio_a);
 241                 goto exit_free_mem;
 242         }
 243
 244         err = gpio_request_one(pdata->gpio_b, GPIOF_IN, dev_name(dev));
 245         if (err) {
 246                 dev_err(dev, "unable to request GPIO %d\n", pdata->gpio_b);
 247                 goto exit_free_gpio_a;
 248         }
 249
 250         encoder->irq_a = gpio_to_irq(pdata->gpio_a);
 251         encoder->irq_b = gpio_to_irq(pdata->gpio_b);
 252
 253         /* request the IRQs */
 254         if (pdata->half_period) {
 255                 handler = &rotary_encoder_half_period_irq;
 256                 encoder->last_stable = rotary_encoder_get_state(pdata);
 257         } else {
 258                 handler = &rotary_encoder_irq;
 259         }
 260
 261         err = request_irq(encoder->irq_a, handler,
 262                           IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
 263                           DRV_NAME, encoder);
 264         if (err) {
 265                 dev_err(dev, "unable to request IRQ %d\n", encoder->irq_a);
 266                 goto exit_free_gpio_b;
 267         }
 268
 269         err = request_irq(encoder->irq_b, handler,
 270                           IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
 271                           DRV_NAME, encoder);
 272         if (err) {
 273                 dev_err(dev, "unable to request IRQ %d\n", encoder->irq_b);
 274                 goto exit_free_irq_a;
 275         }
 276
 277         err = input_register_device(input);
 278         if (err) {
 279                 dev_err(dev, "failed to register input device\n");
 280                 goto exit_free_irq_b;
 281         }
 282
 283         platform_set_drvdata(pdev, encoder);
 284
 285         return 0;
 286
 287 exit_free_irq_b:
 288         free_irq(encoder->irq_b, encoder);
 289 exit_free_irq_a:
 290         free_irq(encoder->irq_a, encoder);
 291 exit_free_gpio_b:
 292         gpio_free(pdata->gpio_b);
 293 exit_free_gpio_a:
 294         gpio_free(pdata->gpio_a);
 295 exit_free_mem:
 296         input_free_device(input);
 297         kfree(encoder);
 298         if (!dev_get_platdata(&pdev->dev))
 299                 kfree(pdata);
 300
 301         return err;
 302 }
 303
 304 static int rotary_encoder_remove(struct platform_device *pdev)
 305 {
 306         struct rotary_encoder *encoder = platform_get_drvdata(pdev);
 307         const struct rotary_encoder_platform_data *pdata = encoder->pdata;
 308
 309         free_irq(encoder->irq_a, encoder);
 310         free_irq(encoder->irq_b, encoder);
 311         gpio_free(pdata->gpio_a);
 312         gpio_free(pdata->gpio_b);
 313
 314         input_unregister_device(encoder->input);
 315         kfree(encoder);
 316
 317         if (!dev_get_platdata(&pdev->dev))
 318                 kfree(pdata);
 319
 320         platform_set_drvdata(pdev, NULL);
 321
 322         return 0;
 323 }
 324
 325 static struct platform_driver rotary_encoder_driver = {
 326         .probe          = rotary_encoder_probe,
 327         .remove         = rotary_encoder_remove,
 328         .driver         = {
 329                 .name   = DRV_NAME,
 330                 .owner  = THIS_MODULE,
 331                 .of_match_table = of_match_ptr(rotary_encoder_of_match),
 332         }
 333 };
 334 module_platform_driver(rotary_encoder_driver);
 335
 336 MODULE_ALIAS("platform:" DRV_NAME);
 337 MODULE_DESCRIPTION("GPIO rotary encoder driver");
 338 MODULE_AUTHOR("Daniel Mack <daniel@caiaq.de>, Johan Hovold");
 339 MODULE_LICENSE("GPL v2");