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
of_get_optional_u32(struct device_node * np,const char * property)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
touchscreen_set_params(struct input_dev * dev,unsigned long axis,int max,int fuzz)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 */
touchscreen_parse_of_params(struct input_dev * dev)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);
88