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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/mod_devicetable.h>
17#include <linux/module.h>
18#include <linux/platform_device.h>
19#include <linux/property.h>
20
21#define DRIVER_NAME "resistive-adc-touch"
22#define GRTS_DEFAULT_PRESSURE_MIN 50000
23#define GRTS_DEFAULT_PRESSURE_MAX 65535
24#define GRTS_MAX_POS_MASK GENMASK(11, 0)
25#define GRTS_MAX_CHANNELS 4
26
27enum grts_ch_type {
28 GRTS_CH_X,
29 GRTS_CH_Y,
30 GRTS_CH_PRESSURE,
31 GRTS_CH_Z1,
32 GRTS_CH_Z2,
33 GRTS_CH_MAX = GRTS_CH_Z2 + 1
34};
35
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40
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43
44
45
46
47struct grts_state {
48 u32 x_plate_ohms;
49 u32 pressure_min;
50 bool pressure;
51 struct iio_channel *iio_chans;
52 struct iio_cb_buffer *iio_cb;
53 struct input_dev *input;
54 struct touchscreen_properties prop;
55 u8 ch_map[GRTS_CH_MAX];
56};
57
58static int grts_cb(const void *data, void *private)
59{
60 const u16 *touch_info = data;
61 struct grts_state *st = private;
62 unsigned int x, y, press = 0;
63
64 x = touch_info[st->ch_map[GRTS_CH_X]];
65 y = touch_info[st->ch_map[GRTS_CH_Y]];
66
67 if (st->ch_map[GRTS_CH_PRESSURE] < GRTS_MAX_CHANNELS) {
68 press = touch_info[st->ch_map[GRTS_CH_PRESSURE]];
69 } else if (st->ch_map[GRTS_CH_Z1] < GRTS_MAX_CHANNELS) {
70 unsigned int z1 = touch_info[st->ch_map[GRTS_CH_Z1]];
71 unsigned int z2 = touch_info[st->ch_map[GRTS_CH_Z2]];
72 unsigned int Rt;
73
74 if (likely(x && z1)) {
75 Rt = z2;
76 Rt -= z1;
77 Rt *= st->x_plate_ohms;
78 Rt = DIV_ROUND_CLOSEST(Rt, 16);
79 Rt *= x;
80 Rt /= z1;
81 Rt = DIV_ROUND_CLOSEST(Rt, 256);
82
83
84
85
86
87 if (Rt < GRTS_DEFAULT_PRESSURE_MAX)
88 press = GRTS_DEFAULT_PRESSURE_MAX - Rt;
89 }
90 }
91
92 if ((!x && !y) || (st->pressure && (press < st->pressure_min))) {
93
94 input_report_key(st->input, BTN_TOUCH, 0);
95 input_sync(st->input);
96 return 0;
97 }
98
99
100 touchscreen_report_pos(st->input, &st->prop, x, y, false);
101 if (st->pressure)
102 input_report_abs(st->input, ABS_PRESSURE, press);
103 input_report_key(st->input, BTN_TOUCH, 1);
104 input_sync(st->input);
105
106 return 0;
107}
108
109static int grts_open(struct input_dev *dev)
110{
111 int error;
112 struct grts_state *st = input_get_drvdata(dev);
113
114 error = iio_channel_start_all_cb(st->iio_cb);
115 if (error) {
116 dev_err(dev->dev.parent, "failed to start callback buffer.\n");
117 return error;
118 }
119 return 0;
120}
121
122static void grts_close(struct input_dev *dev)
123{
124 struct grts_state *st = input_get_drvdata(dev);
125
126 iio_channel_stop_all_cb(st->iio_cb);
127}
128
129static void grts_disable(void *data)
130{
131 iio_channel_release_all_cb(data);
132}
133
134static int grts_map_channel(struct grts_state *st, struct device *dev,
135 enum grts_ch_type type, const char *name,
136 bool optional)
137{
138 int idx;
139
140 idx = device_property_match_string(dev, "io-channel-names", name);
141 if (idx < 0) {
142 if (!optional)
143 return idx;
144 idx = GRTS_MAX_CHANNELS;
145 } else if (idx >= GRTS_MAX_CHANNELS) {
146 return -EOVERFLOW;
147 }
148
149 st->ch_map[type] = idx;
150 return 0;
151}
152
153static int grts_get_properties(struct grts_state *st, struct device *dev)
154{
155 int error;
156
157 error = grts_map_channel(st, dev, GRTS_CH_X, "x", false);
158 if (error)
159 return error;
160
161 error = grts_map_channel(st, dev, GRTS_CH_Y, "y", false);
162 if (error)
163 return error;
164
165
166 error = grts_map_channel(st, dev, GRTS_CH_PRESSURE, "pressure", true);
167 if (error)
168 return error;
169
170 if (st->ch_map[GRTS_CH_PRESSURE] < GRTS_MAX_CHANNELS) {
171 st->pressure = true;
172 return 0;
173 }
174
175
176 error = grts_map_channel(st, dev, GRTS_CH_Z1, "z1", true);
177 if (error)
178 return error;
179
180 if (st->ch_map[GRTS_CH_Z1] >= GRTS_MAX_CHANNELS)
181 return 0;
182
183
184 error = grts_map_channel(st, dev, GRTS_CH_Z2, "z2", true);
185 if (error)
186 return error;
187
188 error = device_property_read_u32(dev,
189 "touchscreen-x-plate-ohms",
190 &st->x_plate_ohms);
191 if (error) {
192 dev_err(dev, "can't get touchscreen-x-plate-ohms property\n");
193 return error;
194 }
195
196 st->pressure = true;
197 return 0;
198}
199
200static int grts_probe(struct platform_device *pdev)
201{
202 struct grts_state *st;
203 struct input_dev *input;
204 struct device *dev = &pdev->dev;
205 int error;
206
207 st = devm_kzalloc(dev, sizeof(struct grts_state), GFP_KERNEL);
208 if (!st)
209 return -ENOMEM;
210
211
212 st->iio_chans = devm_iio_channel_get_all(dev);
213 if (IS_ERR(st->iio_chans)) {
214 error = PTR_ERR(st->iio_chans);
215 if (error != -EPROBE_DEFER)
216 dev_err(dev, "can't get iio channels.\n");
217 return error;
218 }
219
220 if (!device_property_present(dev, "io-channel-names"))
221 return -ENODEV;
222
223 error = grts_get_properties(st, dev);
224 if (error) {
225 dev_err(dev, "Failed to parse properties\n");
226 return error;
227 }
228
229 if (st->pressure) {
230 error = device_property_read_u32(dev,
231 "touchscreen-min-pressure",
232 &st->pressure_min);
233 if (error) {
234 dev_dbg(dev, "can't get touchscreen-min-pressure property.\n");
235 st->pressure_min = GRTS_DEFAULT_PRESSURE_MIN;
236 }
237 }
238
239 input = devm_input_allocate_device(dev);
240 if (!input) {
241 dev_err(dev, "failed to allocate input device.\n");
242 return -ENOMEM;
243 }
244
245 input->name = DRIVER_NAME;
246 input->id.bustype = BUS_HOST;
247 input->open = grts_open;
248 input->close = grts_close;
249
250 input_set_abs_params(input, ABS_X, 0, GRTS_MAX_POS_MASK - 1, 0, 0);
251 input_set_abs_params(input, ABS_Y, 0, GRTS_MAX_POS_MASK - 1, 0, 0);
252 if (st->pressure)
253 input_set_abs_params(input, ABS_PRESSURE, st->pressure_min,
254 GRTS_DEFAULT_PRESSURE_MAX, 0, 0);
255
256 input_set_capability(input, EV_KEY, BTN_TOUCH);
257
258
259 touchscreen_parse_properties(input, false, &st->prop);
260
261 st->input = input;
262 input_set_drvdata(input, st);
263
264 error = input_register_device(input);
265 if (error) {
266 dev_err(dev, "failed to register input device.");
267 return error;
268 }
269
270 st->iio_cb = iio_channel_get_all_cb(dev, grts_cb, st);
271 if (IS_ERR(st->iio_cb)) {
272 dev_err(dev, "failed to allocate callback buffer.\n");
273 return PTR_ERR(st->iio_cb);
274 }
275
276 error = devm_add_action_or_reset(dev, grts_disable, st->iio_cb);
277 if (error) {
278 dev_err(dev, "failed to add disable action.\n");
279 return error;
280 }
281
282 return 0;
283}
284
285static const struct of_device_id grts_of_match[] = {
286 {
287 .compatible = "resistive-adc-touch",
288 }, {
289
290 },
291};
292
293MODULE_DEVICE_TABLE(of, grts_of_match);
294
295static struct platform_driver grts_driver = {
296 .probe = grts_probe,
297 .driver = {
298 .name = DRIVER_NAME,
299 .of_match_table = grts_of_match,
300 },
301};
302
303module_platform_driver(grts_driver);
304
305MODULE_AUTHOR("Eugen Hristev <eugen.hristev@microchip.com>");
306MODULE_DESCRIPTION("Generic ADC Resistive Touch Driver");
307MODULE_LICENSE("GPL v2");
308
