drivers/input/misc/rotary_encoder.c

   1 /*
   2  * rotary_encoder.c
   3  *
   4  * (c) 2009 Daniel Mack <daniel@caiaq.de>
   5  *
   6  * state machine code inspired by code from Tim Ruetz
   7  *
   8  * A generic driver for rotary encoders connected to GPIO lines.
   9  * See file:Documentation/input/rotary_encoder.txt for more information
  10  *
  11  * This program is free software; you can redistribute it and/or modify
  12  * it under the terms of the GNU General Public License version 2 as
  13  * published by the Free Software Foundation.
  14  */
  15
  16 #include <linux/kernel.h>
  17 #include <linux/module.h>
  18 #include <linux/init.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
  27 #define DRV_NAME "rotary-encoder"
  28
  29 struct rotary_encoder {
  30         struct input_dev *input;
  31         struct rotary_encoder_platform_data *pdata;
  32
  33         unsigned int axis;
  34         unsigned int pos;
  35
  36         unsigned int irq_a;
  37         unsigned int irq_b;
  38
  39         bool armed;
  40         unsigned char dir;      /* 0 - clockwise, 1 - CCW */
  41 };
  42
  43 static int rotary_encoder_get_state(struct rotary_encoder_platform_data *pdata)
  44 {
  45         int a = !!gpio_get_value(pdata->gpio_a);
  46         int b = !!gpio_get_value(pdata->gpio_b);
  47
  48         a ^= pdata->inverted_a;
  49         b ^= pdata->inverted_b;
  50
  51         return ((a << 1) | b);
  52 }
  53
  54 static void rotary_encoder_report_event(struct rotary_encoder *encoder)
  55 {
  56         struct rotary_encoder_platform_data *pdata = encoder->pdata;
  57
  58         if (pdata->relative_axis) {
  59                 input_report_rel(encoder->input,
  60                                  pdata->axis, encoder->dir ? -1 : 1);
  61         } else {
  62                 unsigned int pos = encoder->pos;
  63
  64                 if (encoder->dir) {
  65                         /* turning counter-clockwise */
  66                         if (pdata->rollover)
  67                                 pos += pdata->steps;
  68                         if (pos)
  69                                 pos--;
  70                 } else {
  71                         /* turning clockwise */
  72                         if (pdata->rollover || pos < pdata->steps)
  73                                 pos++;
  74                 }
  75
  76                 if (pdata->rollover)
  77                         pos %= pdata->steps;
  78
  79                 encoder->pos = pos;
  80                 input_report_abs(encoder->input, pdata->axis, encoder->pos);
  81         }
  82
  83         input_sync(encoder->input);
  84 }
  85
  86 static irqreturn_t rotary_encoder_irq(int irq, void *dev_id)
  87 {
  88         struct rotary_encoder *encoder = dev_id;
  89         int state;
  90
  91         state = rotary_encoder_get_state(encoder->pdata);
  92
  93         switch (state) {
  94         case 0x0:
  95                 if (encoder->armed) {
  96                         rotary_encoder_report_event(encoder);
  97                         encoder->armed = false;
  98                 }
  99                 break;
 100
 101         case 0x1:
 102         case 0x2:
 103                 if (encoder->armed)
 104                         encoder->dir = state - 1;
 105                 break;
 106
 107         case 0x3:
 108                 encoder->armed = true;
 109                 break;
 110         }
 111
 112         return IRQ_HANDLED;
 113 }
 114
 115 static int __devinit rotary_encoder_probe(struct platform_device *pdev)
 116 {
 117         struct rotary_encoder_platform_data *pdata = pdev->dev.platform_data;
 118         struct rotary_encoder *encoder;
 119         struct input_dev *input;
 120         int err;
 121
 122         if (!pdata) {
 123                 dev_err(&pdev->dev, "missing platform data\n");
 124                 return -ENOENT;
 125         }
 126
 127         encoder = kzalloc(sizeof(struct rotary_encoder), GFP_KERNEL);
 128         input = input_allocate_device();
 129         if (!encoder || !input) {
 130                 dev_err(&pdev->dev, "failed to allocate memory for device\n");
 131                 err = -ENOMEM;
 132                 goto exit_free_mem;
 133         }
 134
 135         encoder->input = input;
 136         encoder->pdata = pdata;
 137         encoder->irq_a = gpio_to_irq(pdata->gpio_a);
 138         encoder->irq_b = gpio_to_irq(pdata->gpio_b);
 139
 140         /* create and register the input driver */
 141         input->name = pdev->name;
 142         input->id.bustype = BUS_HOST;
 143         input->dev.parent = &pdev->dev;
 144
 145         if (pdata->relative_axis) {
 146                 input->evbit[0] = BIT_MASK(EV_REL);
 147                 input->relbit[0] = BIT_MASK(pdata->axis);
 148         } else {
 149                 input->evbit[0] = BIT_MASK(EV_ABS);
 150                 input_set_abs_params(encoder->input,
 151                                      pdata->axis, 0, pdata->steps, 0, 1);
 152         }
 153
 154         err = input_register_device(input);
 155         if (err) {
 156                 dev_err(&pdev->dev, "failed to register input device\n");
 157                 goto exit_free_mem;
 158         }
 159
 160         /* request the GPIOs */
 161         err = gpio_request(pdata->gpio_a, DRV_NAME);
 162         if (err) {
 163                 dev_err(&pdev->dev, "unable to request GPIO %d\n",
 164                         pdata->gpio_a);
 165                 goto exit_unregister_input;
 166         }
 167
 168         err = gpio_direction_input(pdata->gpio_a);
 169         if (err) {
 170                 dev_err(&pdev->dev, "unable to set GPIO %d for input\n",
 171                         pdata->gpio_a);
 172                 goto exit_unregister_input;
 173         }
 174
 175         err = gpio_request(pdata->gpio_b, DRV_NAME);
 176         if (err) {
 177                 dev_err(&pdev->dev, "unable to request GPIO %d\n",
 178                         pdata->gpio_b);
 179                 goto exit_free_gpio_a;
 180         }
 181
 182         err = gpio_direction_input(pdata->gpio_b);
 183         if (err) {
 184                 dev_err(&pdev->dev, "unable to set GPIO %d for input\n",
 185                         pdata->gpio_b);
 186                 goto exit_free_gpio_a;
 187         }
 188
 189         /* request the IRQs */
 190         err = request_irq(encoder->irq_a, &rotary_encoder_irq,
 191                           IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
 192                           DRV_NAME, encoder);
 193         if (err) {
 194                 dev_err(&pdev->dev, "unable to request IRQ %d\n",
 195                         encoder->irq_a);
 196                 goto exit_free_gpio_b;
 197         }
 198
 199         err = request_irq(encoder->irq_b, &rotary_encoder_irq,
 200                           IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
 201                           DRV_NAME, encoder);
 202         if (err) {
 203                 dev_err(&pdev->dev, "unable to request IRQ %d\n",
 204                         encoder->irq_b);
 205                 goto exit_free_irq_a;
 206         }
 207
 208         platform_set_drvdata(pdev, encoder);
 209
 210         return 0;
 211
 212 exit_free_irq_a:
 213         free_irq(encoder->irq_a, encoder);
 214 exit_free_gpio_b:
 215         gpio_free(pdata->gpio_b);
 216 exit_free_gpio_a:
 217         gpio_free(pdata->gpio_a);
 218 exit_unregister_input:
 219         input_unregister_device(input);
 220         input = NULL; /* so we don't try to free it */
 221 exit_free_mem:
 222         input_free_device(input);
 223         kfree(encoder);
 224         return err;
 225 }
 226
 227 static int __devexit rotary_encoder_remove(struct platform_device *pdev)
 228 {
 229         struct rotary_encoder *encoder = platform_get_drvdata(pdev);
 230         struct rotary_encoder_platform_data *pdata = pdev->dev.platform_data;
 231
 232         free_irq(encoder->irq_a, encoder);
 233         free_irq(encoder->irq_b, encoder);
 234         gpio_free(pdata->gpio_a);
 235         gpio_free(pdata->gpio_b);
 236         input_unregister_device(encoder->input);
 237         platform_set_drvdata(pdev, NULL);
 238         kfree(encoder);
 239
 240         return 0;
 241 }
 242
 243 static struct platform_driver rotary_encoder_driver = {
 244         .probe          = rotary_encoder_probe,
 245         .remove         = __devexit_p(rotary_encoder_remove),
 246         .driver         = {
 247                 .name   = DRV_NAME,
 248                 .owner  = THIS_MODULE,
 249         }
 250 };
 251
 252 static int __init rotary_encoder_init(void)
 253 {
 254         return platform_driver_register(&rotary_encoder_driver);
 255 }
 256
 257 static void __exit rotary_encoder_exit(void)
 258 {
 259         platform_driver_unregister(&rotary_encoder_driver);
 260 }
 261
 262 module_init(rotary_encoder_init);
 263 module_exit(rotary_encoder_exit);
 264
 265 MODULE_ALIAS("platform:" DRV_NAME);
 266 MODULE_DESCRIPTION("GPIO rotary encoder driver");
 267 MODULE_AUTHOR("Daniel Mack <daniel@caiaq.de>");
 268 MODULE_LICENSE("GPL v2");