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 u32 of_get_optional_u32(struct device_node *np,
  18                                const char *property)
  19 {
  20         u32 val = 0;
  21
  22         of_property_read_u32(np, property, &val);
  23
  24         return val;
  25 }
  26
  27 static void touchscreen_set_params(struct input_dev *dev,
  28                                    unsigned long axis,
  29                                    int max, int fuzz)
  30 {
  31         struct input_absinfo *absinfo;
  32
  33         if (!test_bit(axis, dev->absbit)) {
  34                 /*
  35                  * Emit a warning only if the axis is not a multitouch
  36                  * axis, which might not be set by the driver.
  37                  */
  38                 if (!input_is_mt_axis(axis))
  39                         dev_warn(&dev->dev,
  40                                  "DT specifies parameters but the axis is not set up\n");
  41                 return;
  42         }
  43
  44         absinfo = &dev->absinfo[axis];
  45         absinfo->maximum = max;
  46         absinfo->fuzz = fuzz;
  47 }
  48
  49 /**
  50  * touchscreen_parse_of_params - parse common touchscreen DT properties
  51  * @dev: device that should be parsed
  52  *
  53  * This function parses common DT properties for touchscreens and setups the
  54  * input device accordingly. The function keeps previously setuped default
  55  * values if no value is specified via DT.
  56  */
  57 void touchscreen_parse_of_params(struct input_dev *dev)
  58 {
  59         struct device_node *np = dev->dev.parent->of_node;
  60         u32 maximum, fuzz;
  61
  62         input_alloc_absinfo(dev);
  63         if (!dev->absinfo)
  64                 return;
  65
  66         maximum = of_get_optional_u32(np, "touchscreen-size-x");
  67         fuzz = of_get_optional_u32(np, "touchscreen-fuzz-x");
  68         if (maximum || fuzz) {
  69                 touchscreen_set_params(dev, ABS_X, maximum, fuzz);
  70                 touchscreen_set_params(dev, ABS_MT_POSITION_X, maximum, fuzz);
  71         }
  72
  73         maximum = of_get_optional_u32(np, "touchscreen-size-y");
  74         fuzz = of_get_optional_u32(np, "touchscreen-fuzz-y");
  75         if (maximum || fuzz) {
  76                 touchscreen_set_params(dev, ABS_Y, maximum, fuzz);
  77                 touchscreen_set_params(dev, ABS_MT_POSITION_Y, maximum, fuzz);
  78         }
  79
  80         maximum = of_get_optional_u32(np, "touchscreen-max-pressure");
  81         fuzz = of_get_optional_u32(np, "touchscreen-fuzz-pressure");
  82         if (maximum || fuzz) {
  83                 touchscreen_set_params(dev, ABS_PRESSURE, maximum, fuzz);
  84                 touchscreen_set_params(dev, ABS_MT_PRESSURE, maximum, fuzz);
  85         }
  86 }
  87 EXPORT_SYMBOL(touchscreen_parse_of_params);