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1 | // SPDX-License-Identifier: GPL-2.0 |
2 | /* | |
3 | * ADC generic resistive touchscreen (GRTS) | |
4 | * This is a generic input driver that connects to an ADC | |
5 | * given the channels in device tree, and reports events to the input | |
6 | * subsystem. | |
7 | * | |
8 | * Copyright (C) 2017,2018 Microchip Technology, | |
9 | * Author: Eugen Hristev <eugen.hristev@microchip.com> | |
10 | * | |
11 | */ | |
12 | #include <linux/input.h> | |
13 | #include <linux/input/touchscreen.h> | |
14 | #include <linux/iio/consumer.h> | |
15 | #include <linux/iio/iio.h> | |
16 | #include <linux/module.h> | |
17 | #include <linux/of.h> | |
18 | #include <linux/of_device.h> | |
19 | #include <linux/platform_device.h> | |
20 | ||
21 | #define DRIVER_NAME "resistive-adc-touch" | |
22 | #define GRTS_DEFAULT_PRESSURE_MIN 50000 | |
23 | #define GRTS_MAX_POS_MASK GENMASK(11, 0) | |
24 | ||
25 | /** | |
26 | * grts_state - generic resistive touch screen information struct | |
27 | * @pressure_min: number representing the minimum for the pressure | |
28 | * @pressure: are we getting pressure info or not | |
29 | * @iio_chans: list of channels acquired | |
30 | * @iio_cb: iio_callback buffer for the data | |
31 | * @input: the input device structure that we register | |
32 | * @prop: touchscreen properties struct | |
33 | */ | |
34 | struct grts_state { | |
35 | u32 pressure_min; | |
36 | bool pressure; | |
37 | struct iio_channel *iio_chans; | |
38 | struct iio_cb_buffer *iio_cb; | |
39 | struct input_dev *input; | |
40 | struct touchscreen_properties prop; | |
41 | }; | |
42 | ||
43 | static int grts_cb(const void *data, void *private) | |
44 | { | |
45 | const u16 *touch_info = data; | |
46 | struct grts_state *st = private; | |
47 | unsigned int x, y, press = 0x0; | |
48 | ||
49 | /* channel data coming in buffer in the order below */ | |
50 | x = touch_info[0]; | |
51 | y = touch_info[1]; | |
52 | if (st->pressure) | |
53 | press = touch_info[2]; | |
54 | ||
55 | if ((!x && !y) || (st->pressure && (press < st->pressure_min))) { | |
56 | /* report end of touch */ | |
57 | input_report_key(st->input, BTN_TOUCH, 0); | |
58 | input_sync(st->input); | |
59 | return 0; | |
60 | } | |
61 | ||
62 | /* report proper touch to subsystem*/ | |
63 | touchscreen_report_pos(st->input, &st->prop, x, y, false); | |
64 | if (st->pressure) | |
65 | input_report_abs(st->input, ABS_PRESSURE, press); | |
66 | input_report_key(st->input, BTN_TOUCH, 1); | |
67 | input_sync(st->input); | |
68 | ||
69 | return 0; | |
70 | } | |
71 | ||
72 | static int grts_open(struct input_dev *dev) | |
73 | { | |
74 | int error; | |
75 | struct grts_state *st = input_get_drvdata(dev); | |
76 | ||
77 | error = iio_channel_start_all_cb(st->iio_cb); | |
78 | if (error) { | |
79 | dev_err(dev->dev.parent, "failed to start callback buffer.\n"); | |
80 | return error; | |
81 | } | |
82 | return 0; | |
83 | } | |
84 | ||
85 | static void grts_close(struct input_dev *dev) | |
86 | { | |
87 | struct grts_state *st = input_get_drvdata(dev); | |
88 | ||
89 | iio_channel_stop_all_cb(st->iio_cb); | |
90 | } | |
91 | ||
92 | static void grts_disable(void *data) | |
93 | { | |
94 | iio_channel_release_all_cb(data); | |
95 | } | |
96 | ||
97 | static int grts_probe(struct platform_device *pdev) | |
98 | { | |
99 | struct grts_state *st; | |
100 | struct input_dev *input; | |
101 | struct device *dev = &pdev->dev; | |
102 | struct iio_channel *chan; | |
103 | int error; | |
104 | ||
105 | st = devm_kzalloc(dev, sizeof(struct grts_state), GFP_KERNEL); | |
106 | if (!st) | |
107 | return -ENOMEM; | |
108 | ||
109 | /* get the channels from IIO device */ | |
110 | st->iio_chans = devm_iio_channel_get_all(dev); | |
111 | if (IS_ERR(st->iio_chans)) { | |
112 | error = PTR_ERR(st->iio_chans); | |
113 | if (error != -EPROBE_DEFER) | |
114 | dev_err(dev, "can't get iio channels.\n"); | |
115 | return error; | |
116 | } | |
117 | ||
118 | chan = &st->iio_chans[0]; | |
119 | st->pressure = false; | |
120 | while (chan && chan->indio_dev) { | |
121 | if (!strcmp(chan->channel->datasheet_name, "pressure")) | |
122 | st->pressure = true; | |
123 | chan++; | |
124 | } | |
125 | ||
126 | if (st->pressure) { | |
127 | error = device_property_read_u32(dev, | |
128 | "touchscreen-min-pressure", | |
129 | &st->pressure_min); | |
130 | if (error) { | |
131 | dev_dbg(dev, "can't get touchscreen-min-pressure property.\n"); | |
132 | st->pressure_min = GRTS_DEFAULT_PRESSURE_MIN; | |
133 | } | |
134 | } | |
135 | ||
136 | input = devm_input_allocate_device(dev); | |
137 | if (!input) { | |
138 | dev_err(dev, "failed to allocate input device.\n"); | |
139 | return -ENOMEM; | |
140 | } | |
141 | ||
142 | input->name = DRIVER_NAME; | |
143 | input->id.bustype = BUS_HOST; | |
144 | input->open = grts_open; | |
145 | input->close = grts_close; | |
146 | ||
147 | input_set_abs_params(input, ABS_X, 0, GRTS_MAX_POS_MASK - 1, 0, 0); | |
148 | input_set_abs_params(input, ABS_Y, 0, GRTS_MAX_POS_MASK - 1, 0, 0); | |
149 | if (st->pressure) | |
150 | input_set_abs_params(input, ABS_PRESSURE, st->pressure_min, | |
151 | 0xffff, 0, 0); | |
152 | ||
153 | input_set_capability(input, EV_KEY, BTN_TOUCH); | |
154 | ||
155 | /* parse optional device tree properties */ | |
156 | touchscreen_parse_properties(input, false, &st->prop); | |
157 | ||
158 | st->input = input; | |
159 | input_set_drvdata(input, st); | |
160 | ||
161 | error = input_register_device(input); | |
162 | if (error) { | |
163 | dev_err(dev, "failed to register input device."); | |
164 | return error; | |
165 | } | |
166 | ||
167 | st->iio_cb = iio_channel_get_all_cb(dev, grts_cb, st); | |
168 | if (IS_ERR(st->iio_cb)) { | |
169 | dev_err(dev, "failed to allocate callback buffer.\n"); | |
170 | return PTR_ERR(st->iio_cb); | |
171 | } | |
172 | ||
173 | error = devm_add_action_or_reset(dev, grts_disable, st->iio_cb); | |
174 | if (error) { | |
175 | dev_err(dev, "failed to add disable action.\n"); | |
176 | return error; | |
177 | } | |
178 | ||
179 | return 0; | |
180 | } | |
181 | ||
182 | static const struct of_device_id grts_of_match[] = { | |
183 | { | |
184 | .compatible = "resistive-adc-touch", | |
185 | }, { | |
186 | /* sentinel */ | |
187 | }, | |
188 | }; | |
189 | ||
190 | MODULE_DEVICE_TABLE(of, grts_of_match); | |
191 | ||
192 | static struct platform_driver grts_driver = { | |
193 | .probe = grts_probe, | |
194 | .driver = { | |
195 | .name = DRIVER_NAME, | |
196 | .of_match_table = of_match_ptr(grts_of_match), | |
197 | }, | |
198 | }; | |
199 | ||
200 | module_platform_driver(grts_driver); | |
201 | ||
202 | MODULE_AUTHOR("Eugen Hristev <eugen.hristev@microchip.com>"); | |
203 | MODULE_DESCRIPTION("Generic ADC Resistive Touch Driver"); | |
204 | MODULE_LICENSE("GPL v2"); |