drivers/input/touchscreen/of_touchscreen.c

   1 /*
   2  *  Generic DT helper functions for touchscreen devices
   3  *
   4  *  Copyright (c) 2014 Sebastian Reichel <sre@kernel.org>
   5  *
   6  *  This program is free software; you can redistribute it and/or modify
   7  *  it under the terms of the GNU General Public License version 2 as
   8  *  published by the Free Software Foundation.
   9  *
  10  */
  11
  12 #include <linux/of.h>
  13 #include <linux/input.h>
  14 #include <linux/input/mt.h>
  15 #include <linux/input/touchscreen.h>
  16
  17 static bool touchscreen_get_prop_u32(struct device_node *np,
  18                                      const char *property,
  19                                      unsigned int default_value,
  20                                      unsigned int *value)
  21 {
  22         u32 val;
  23         int error;
  24
  25         error = of_property_read_u32(np, property, &val);
  26         if (error) {
  27                 *value = default_value;
  28                 return false;
  29         }
  30
  31         *value = val;
  32         return true;
  33 }
  34
  35 static void touchscreen_set_params(struct input_dev *dev,
  36                                    unsigned long axis,
  37                                    int max, int fuzz)
  38 {
  39         struct input_absinfo *absinfo;
  40
  41         if (!test_bit(axis, dev->absbit)) {
  42                 dev_warn(&dev->dev,
  43                          "DT specifies parameters but the axis %lu is not set up\n",
  44                          axis);
  45                 return;
  46         }
  47
  48         absinfo = &dev->absinfo[axis];
  49         absinfo->maximum = max;
  50         absinfo->fuzz = fuzz;
  51 }
  52
  53 /**
  54  * touchscreen_parse_of_params - parse common touchscreen DT properties
  55  * @dev: device that should be parsed
  56  *
  57  * This function parses common DT properties for touchscreens and setups the
  58  * input device accordingly. The function keeps previously setuped default
  59  * values if no value is specified via DT.
  60  */
  61 void touchscreen_parse_of_params(struct input_dev *dev, bool multitouch)
  62 {
  63         struct device_node *np = dev->dev.parent->of_node;
  64         unsigned int axis;
  65         unsigned int maximum, fuzz;
  66         bool data_present;
  67
  68         input_alloc_absinfo(dev);
  69         if (!dev->absinfo)
  70                 return;
  71
  72         axis = multitouch ? ABS_MT_POSITION_X : ABS_X;
  73         data_present = touchscreen_get_prop_u32(np, "touchscreen-size-x",
  74                                                 input_abs_get_max(dev,
  75                                                                   axis) + 1,
  76                                                 &maximum) |
  77                        touchscreen_get_prop_u32(np, "touchscreen-fuzz-x",
  78                                                 input_abs_get_fuzz(dev, axis),
  79                                                 &fuzz);
  80         if (data_present)
  81                 touchscreen_set_params(dev, axis, maximum - 1, fuzz);
  82
  83         axis = multitouch ? ABS_MT_POSITION_Y : ABS_Y;
  84         data_present = touchscreen_get_prop_u32(np, "touchscreen-size-y",
  85                                                 input_abs_get_max(dev,
  86                                                                   axis) + 1,
  87                                                 &maximum) |
  88                        touchscreen_get_prop_u32(np, "touchscreen-fuzz-y",
  89                                                 input_abs_get_fuzz(dev, axis),
  90                                                 &fuzz);
  91         if (data_present)
  92                 touchscreen_set_params(dev, axis, maximum - 1, fuzz);
  93
  94         axis = multitouch ? ABS_MT_PRESSURE : ABS_PRESSURE;
  95         data_present = touchscreen_get_prop_u32(np, "touchscreen-max-pressure",
  96                                                 input_abs_get_max(dev, axis),
  97                                                 &maximum) |
  98                        touchscreen_get_prop_u32(np, "touchscreen-fuzz-pressure",
  99                                                 input_abs_get_fuzz(dev, axis),
 100                                                 &fuzz);
 101         if (data_present)
 102                 touchscreen_set_params(dev, axis, maximum, fuzz);
 103 }
 104 EXPORT_SYMBOL(touchscreen_parse_of_params);