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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 | // SPDX-License-Identifier: GPL-2.0 /* * ADC generic resistive touchscreen (GRTS) * This is a generic input driver that connects to an ADC * given the channels in device tree, and reports events to the input * subsystem. * * Copyright (C) 2017,2018 Microchip Technology, * Author: Eugen Hristev <eugen.hristev@microchip.com> * */ #include <linux/input.h> #include <linux/input/touchscreen.h> #include <linux/iio/consumer.h> #include <linux/iio/iio.h> #include <linux/mod_devicetable.h> #include <linux/module.h> #include <linux/platform_device.h> #include <linux/property.h> #define DRIVER_NAME "resistive-adc-touch" #define GRTS_DEFAULT_PRESSURE_MIN 50000 #define GRTS_DEFAULT_PRESSURE_MAX 65535 #define GRTS_MAX_POS_MASK GENMASK(11, 0) #define GRTS_MAX_CHANNELS 4 enum grts_ch_type { GRTS_CH_X, GRTS_CH_Y, GRTS_CH_PRESSURE, GRTS_CH_Z1, GRTS_CH_Z2, GRTS_CH_MAX = GRTS_CH_Z2 + 1 }; /** * struct grts_state - generic resistive touch screen information struct * @x_plate_ohms: resistance of the X plate * @pressure_min: number representing the minimum for the pressure * @pressure: are we getting pressure info or not * @iio_chans: list of channels acquired * @iio_cb: iio_callback buffer for the data * @input: the input device structure that we register * @prop: touchscreen properties struct * @ch_map: map of channels that are defined for the touchscreen */ struct grts_state { u32 x_plate_ohms; u32 pressure_min; bool pressure; struct iio_channel *iio_chans; struct iio_cb_buffer *iio_cb; struct input_dev *input; struct touchscreen_properties prop; u8 ch_map[GRTS_CH_MAX]; }; static int grts_cb(const void *data, void *private) { const u16 *touch_info = data; struct grts_state *st = private; unsigned int x, y, press = 0; x = touch_info[st->ch_map[GRTS_CH_X]]; y = touch_info[st->ch_map[GRTS_CH_Y]]; if (st->ch_map[GRTS_CH_PRESSURE] < GRTS_MAX_CHANNELS) { press = touch_info[st->ch_map[GRTS_CH_PRESSURE]]; } else if (st->ch_map[GRTS_CH_Z1] < GRTS_MAX_CHANNELS) { unsigned int z1 = touch_info[st->ch_map[GRTS_CH_Z1]]; unsigned int z2 = touch_info[st->ch_map[GRTS_CH_Z2]]; unsigned int Rt; if (likely(x && z1)) { Rt = z2; Rt -= z1; Rt *= st->x_plate_ohms; Rt = DIV_ROUND_CLOSEST(Rt, 16); Rt *= x; Rt /= z1; Rt = DIV_ROUND_CLOSEST(Rt, 256); /* * On increased pressure the resistance (Rt) is * decreasing so, convert values to make it looks as * real pressure. */ if (Rt < GRTS_DEFAULT_PRESSURE_MAX) press = GRTS_DEFAULT_PRESSURE_MAX - Rt; } } if ((!x && !y) || (st->pressure && (press < st->pressure_min))) { /* report end of touch */ input_report_key(st->input, BTN_TOUCH, 0); input_sync(st->input); return 0; } /* report proper touch to subsystem*/ touchscreen_report_pos(st->input, &st->prop, x, y, false); if (st->pressure) input_report_abs(st->input, ABS_PRESSURE, press); input_report_key(st->input, BTN_TOUCH, 1); input_sync(st->input); return 0; } static int grts_open(struct input_dev *dev) { int error; struct grts_state *st = input_get_drvdata(dev); error = iio_channel_start_all_cb(st->iio_cb); if (error) { dev_err(dev->dev.parent, "failed to start callback buffer.\n"); return error; } return 0; } static void grts_close(struct input_dev *dev) { struct grts_state *st = input_get_drvdata(dev); iio_channel_stop_all_cb(st->iio_cb); } static void grts_disable(void *data) { iio_channel_release_all_cb(data); } static int grts_map_channel(struct grts_state *st, struct device *dev, enum grts_ch_type type, const char *name, bool optional) { int idx; idx = device_property_match_string(dev, "io-channel-names", name); if (idx < 0) { if (!optional) return idx; idx = GRTS_MAX_CHANNELS; } else if (idx >= GRTS_MAX_CHANNELS) { return -EOVERFLOW; } st->ch_map[type] = idx; return 0; } static int grts_get_properties(struct grts_state *st, struct device *dev) { int error; error = grts_map_channel(st, dev, GRTS_CH_X, "x", false); if (error) return error; error = grts_map_channel(st, dev, GRTS_CH_Y, "y", false); if (error) return error; /* pressure is optional */ error = grts_map_channel(st, dev, GRTS_CH_PRESSURE, "pressure", true); if (error) return error; if (st->ch_map[GRTS_CH_PRESSURE] < GRTS_MAX_CHANNELS) { st->pressure = true; return 0; } /* if no pressure is defined, try optional z1 + z2 */ error = grts_map_channel(st, dev, GRTS_CH_Z1, "z1", true); if (error) return error; if (st->ch_map[GRTS_CH_Z1] >= GRTS_MAX_CHANNELS) return 0; /* if z1 is provided z2 is not optional */ error = grts_map_channel(st, dev, GRTS_CH_Z2, "z2", true); if (error) return error; error = device_property_read_u32(dev, "touchscreen-x-plate-ohms", &st->x_plate_ohms); if (error) { dev_err(dev, "can't get touchscreen-x-plate-ohms property\n"); return error; } st->pressure = true; return 0; } static int grts_probe(struct platform_device *pdev) { struct grts_state *st; struct input_dev *input; struct device *dev = &pdev->dev; int error; st = devm_kzalloc(dev, sizeof(struct grts_state), GFP_KERNEL); if (!st) return -ENOMEM; /* get the channels from IIO device */ st->iio_chans = devm_iio_channel_get_all(dev); if (IS_ERR(st->iio_chans)) { error = PTR_ERR(st->iio_chans); if (error != -EPROBE_DEFER) dev_err(dev, "can't get iio channels.\n"); return error; } if (!device_property_present(dev, "io-channel-names")) return -ENODEV; error = grts_get_properties(st, dev); if (error) { dev_err(dev, "Failed to parse properties\n"); return error; } if (st->pressure) { error = device_property_read_u32(dev, "touchscreen-min-pressure", &st->pressure_min); if (error) { dev_dbg(dev, "can't get touchscreen-min-pressure property.\n"); st->pressure_min = GRTS_DEFAULT_PRESSURE_MIN; } } input = devm_input_allocate_device(dev); if (!input) { dev_err(dev, "failed to allocate input device.\n"); return -ENOMEM; } input->name = DRIVER_NAME; input->id.bustype = BUS_HOST; input->open = grts_open; input->close = grts_close; input_set_abs_params(input, ABS_X, 0, GRTS_MAX_POS_MASK - 1, 0, 0); input_set_abs_params(input, ABS_Y, 0, GRTS_MAX_POS_MASK - 1, 0, 0); if (st->pressure) input_set_abs_params(input, ABS_PRESSURE, st->pressure_min, GRTS_DEFAULT_PRESSURE_MAX, 0, 0); input_set_capability(input, EV_KEY, BTN_TOUCH); /* parse optional device tree properties */ touchscreen_parse_properties(input, false, &st->prop); st->input = input; input_set_drvdata(input, st); error = input_register_device(input); if (error) { dev_err(dev, "failed to register input device."); return error; } st->iio_cb = iio_channel_get_all_cb(dev, grts_cb, st); if (IS_ERR(st->iio_cb)) { dev_err(dev, "failed to allocate callback buffer.\n"); return PTR_ERR(st->iio_cb); } error = devm_add_action_or_reset(dev, grts_disable, st->iio_cb); if (error) { dev_err(dev, "failed to add disable action.\n"); return error; } return 0; } static const struct of_device_id grts_of_match[] = { { .compatible = "resistive-adc-touch", }, { /* sentinel */ }, }; MODULE_DEVICE_TABLE(of, grts_of_match); static struct platform_driver grts_driver = { .probe = grts_probe, .driver = { .name = DRIVER_NAME, .of_match_table = grts_of_match, }, }; module_platform_driver(grts_driver); MODULE_AUTHOR("Eugen Hristev <eugen.hristev@microchip.com>"); MODULE_DESCRIPTION("Generic ADC Resistive Touch Driver"); MODULE_LICENSE("GPL v2"); |