1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * Toradex Colibri VF50 Touchscreen driver 4 * 5 * Copyright 2015 Toradex AG 6 * 7 * Originally authored by Stefan Agner for 3.0 kernel 8 */ 9 10 #include <linux/delay.h> 11 #include <linux/err.h> 12 #include <linux/gpio/consumer.h> 13 #include <linux/iio/consumer.h> 14 #include <linux/iio/types.h> 15 #include <linux/input.h> 16 #include <linux/interrupt.h> 17 #include <linux/kernel.h> 18 #include <linux/module.h> 19 #include <linux/of.h> 20 #include <linux/pinctrl/consumer.h> 21 #include <linux/platform_device.h> 22 #include <linux/slab.h> 23 #include <linux/types.h> 24 25 #define DRIVER_NAME "colibri-vf50-ts" 26 27 #define VF_ADC_MAX ((1 << 12) - 1) 28 29 #define COLI_TOUCH_MIN_DELAY_US 1000 30 #define COLI_TOUCH_MAX_DELAY_US 2000 31 #define COLI_PULLUP_MIN_DELAY_US 10000 32 #define COLI_PULLUP_MAX_DELAY_US 11000 33 #define COLI_TOUCH_NO_OF_AVGS 5 34 #define COLI_TOUCH_REQ_ADC_CHAN 4 35 36 struct vf50_touch_device { 37 struct platform_device *pdev; 38 struct input_dev *ts_input; 39 struct iio_channel *channels; 40 struct gpio_desc *gpio_xp; 41 struct gpio_desc *gpio_xm; 42 struct gpio_desc *gpio_yp; 43 struct gpio_desc *gpio_ym; 44 int pen_irq; 45 int min_pressure; 46 bool stop_touchscreen; 47 }; 48 49 /* 50 * Enables given plates and measures touch parameters using ADC 51 */ 52 static int adc_ts_measure(struct iio_channel *channel, 53 struct gpio_desc *plate_p, struct gpio_desc *plate_m) 54 { 55 int i, value = 0, val = 0; 56 int error; 57 58 gpiod_set_value(plate_p, 1); 59 gpiod_set_value(plate_m, 1); 60 61 usleep_range(COLI_TOUCH_MIN_DELAY_US, COLI_TOUCH_MAX_DELAY_US); 62 63 for (i = 0; i < COLI_TOUCH_NO_OF_AVGS; i++) { 64 error = iio_read_channel_raw(channel, &val); 65 if (error < 0) { 66 value = error; 67 goto error_iio_read; 68 } 69 70 value += val; 71 } 72 73 value /= COLI_TOUCH_NO_OF_AVGS; 74 75 error_iio_read: 76 gpiod_set_value(plate_p, 0); 77 gpiod_set_value(plate_m, 0); 78 79 return value; 80 } 81 82 /* 83 * Enable touch detection using falling edge detection on XM 84 */ 85 static void vf50_ts_enable_touch_detection(struct vf50_touch_device *vf50_ts) 86 { 87 /* Enable plate YM (needs to be strong GND, high active) */ 88 gpiod_set_value(vf50_ts->gpio_ym, 1); 89 90 /* 91 * Let the platform mux to idle state in order to enable 92 * Pull-Up on GPIO 93 */ 94 pinctrl_pm_select_idle_state(&vf50_ts->pdev->dev); 95 96 /* Wait for the pull-up to be stable on high */ 97 usleep_range(COLI_PULLUP_MIN_DELAY_US, COLI_PULLUP_MAX_DELAY_US); 98 } 99 100 /* 101 * ADC touch screen sampling bottom half irq handler 102 */ 103 static irqreturn_t vf50_ts_irq_bh(int irq, void *private) 104 { 105 struct vf50_touch_device *vf50_ts = private; 106 struct device *dev = &vf50_ts->pdev->dev; 107 int val_x, val_y, val_z1, val_z2, val_p = 0; 108 bool discard_val_on_start = true; 109 110 /* Disable the touch detection plates */ 111 gpiod_set_value(vf50_ts->gpio_ym, 0); 112 113 /* Let the platform mux to default state in order to mux as ADC */ 114 pinctrl_pm_select_default_state(dev); 115 116 while (!vf50_ts->stop_touchscreen) { 117 /* X-Direction */ 118 val_x = adc_ts_measure(&vf50_ts->channels[0], 119 vf50_ts->gpio_xp, vf50_ts->gpio_xm); 120 if (val_x < 0) 121 break; 122 123 /* Y-Direction */ 124 val_y = adc_ts_measure(&vf50_ts->channels[1], 125 vf50_ts->gpio_yp, vf50_ts->gpio_ym); 126 if (val_y < 0) 127 break; 128 129 /* 130 * Touch pressure 131 * Measure on XP/YM 132 */ 133 val_z1 = adc_ts_measure(&vf50_ts->channels[2], 134 vf50_ts->gpio_yp, vf50_ts->gpio_xm); 135 if (val_z1 < 0) 136 break; 137 val_z2 = adc_ts_measure(&vf50_ts->channels[3], 138 vf50_ts->gpio_yp, vf50_ts->gpio_xm); 139 if (val_z2 < 0) 140 break; 141 142 /* Validate signal (avoid calculation using noise) */ 143 if (val_z1 > 64 && val_x > 64) { 144 /* 145 * Calculate resistance between the plates 146 * lower resistance means higher pressure 147 */ 148 int r_x = (1000 * val_x) / VF_ADC_MAX; 149 150 val_p = (r_x * val_z2) / val_z1 - r_x; 151 152 } else { 153 val_p = 2000; 154 } 155 156 val_p = 2000 - val_p; 157 dev_dbg(dev, 158 "Measured values: x: %d, y: %d, z1: %d, z2: %d, p: %d\n", 159 val_x, val_y, val_z1, val_z2, val_p); 160 161 /* 162 * If touch pressure is too low, stop measuring and reenable 163 * touch detection 164 */ 165 if (val_p < vf50_ts->min_pressure || val_p > 2000) 166 break; 167 168 /* 169 * The pressure may not be enough for the first x and the 170 * second y measurement, but, the pressure is ok when the 171 * driver is doing the third and fourth measurement. To 172 * take care of this, we drop the first measurement always. 173 */ 174 if (discard_val_on_start) { 175 discard_val_on_start = false; 176 } else { 177 /* 178 * Report touch position and sleep for 179 * the next measurement. 180 */ 181 input_report_abs(vf50_ts->ts_input, 182 ABS_X, VF_ADC_MAX - val_x); 183 input_report_abs(vf50_ts->ts_input, 184 ABS_Y, VF_ADC_MAX - val_y); 185 input_report_abs(vf50_ts->ts_input, 186 ABS_PRESSURE, val_p); 187 input_report_key(vf50_ts->ts_input, BTN_TOUCH, 1); 188 input_sync(vf50_ts->ts_input); 189 } 190 191 usleep_range(COLI_PULLUP_MIN_DELAY_US, 192 COLI_PULLUP_MAX_DELAY_US); 193 } 194 195 /* Report no more touch, re-enable touch detection */ 196 input_report_abs(vf50_ts->ts_input, ABS_PRESSURE, 0); 197 input_report_key(vf50_ts->ts_input, BTN_TOUCH, 0); 198 input_sync(vf50_ts->ts_input); 199 200 vf50_ts_enable_touch_detection(vf50_ts); 201 202 return IRQ_HANDLED; 203 } 204 205 static int vf50_ts_open(struct input_dev *dev_input) 206 { 207 struct vf50_touch_device *touchdev = input_get_drvdata(dev_input); 208 struct device *dev = &touchdev->pdev->dev; 209 210 dev_dbg(dev, "Input device %s opened, starting touch detection\n", 211 dev_input->name); 212 213 touchdev->stop_touchscreen = false; 214 215 /* Mux detection before request IRQ, wait for pull-up to settle */ 216 vf50_ts_enable_touch_detection(touchdev); 217 218 return 0; 219 } 220 221 static void vf50_ts_close(struct input_dev *dev_input) 222 { 223 struct vf50_touch_device *touchdev = input_get_drvdata(dev_input); 224 struct device *dev = &touchdev->pdev->dev; 225 226 touchdev->stop_touchscreen = true; 227 228 /* Make sure IRQ is not running past close */ 229 mb(); 230 synchronize_irq(touchdev->pen_irq); 231 232 gpiod_set_value(touchdev->gpio_ym, 0); 233 pinctrl_pm_select_default_state(dev); 234 235 dev_dbg(dev, "Input device %s closed, disable touch detection\n", 236 dev_input->name); 237 } 238 239 static int vf50_ts_get_gpiod(struct device *dev, struct gpio_desc **gpio_d, 240 const char *con_id, enum gpiod_flags flags) 241 { 242 int error; 243 244 *gpio_d = devm_gpiod_get(dev, con_id, flags); 245 if (IS_ERR(*gpio_d)) { 246 error = PTR_ERR(*gpio_d); 247 dev_err(dev, "Could not get gpio_%s %d\n", con_id, error); 248 return error; 249 } 250 251 return 0; 252 } 253 254 static void vf50_ts_channel_release(void *data) 255 { 256 struct iio_channel *channels = data; 257 258 iio_channel_release_all(channels); 259 } 260 261 static int vf50_ts_probe(struct platform_device *pdev) 262 { 263 struct input_dev *input; 264 struct iio_channel *channels; 265 struct device *dev = &pdev->dev; 266 struct vf50_touch_device *touchdev; 267 int num_adc_channels; 268 int error; 269 270 channels = iio_channel_get_all(dev); 271 if (IS_ERR(channels)) 272 return PTR_ERR(channels); 273 274 error = devm_add_action(dev, vf50_ts_channel_release, channels); 275 if (error) { 276 iio_channel_release_all(channels); 277 dev_err(dev, "Failed to register iio channel release action"); 278 return error; 279 } 280 281 num_adc_channels = 0; 282 while (channels[num_adc_channels].indio_dev) 283 num_adc_channels++; 284 285 if (num_adc_channels != COLI_TOUCH_REQ_ADC_CHAN) { 286 dev_err(dev, "Inadequate ADC channels specified\n"); 287 return -EINVAL; 288 } 289 290 touchdev = devm_kzalloc(dev, sizeof(*touchdev), GFP_KERNEL); 291 if (!touchdev) 292 return -ENOMEM; 293 294 touchdev->pdev = pdev; 295 touchdev->channels = channels; 296 297 error = of_property_read_u32(dev->of_node, "vf50-ts-min-pressure", 298 &touchdev->min_pressure); 299 if (error) 300 return error; 301 302 input = devm_input_allocate_device(dev); 303 if (!input) { 304 dev_err(dev, "Failed to allocate TS input device\n"); 305 return -ENOMEM; 306 } 307 308 input->name = DRIVER_NAME; 309 input->id.bustype = BUS_HOST; 310 input->dev.parent = dev; 311 input->open = vf50_ts_open; 312 input->close = vf50_ts_close; 313 314 input_set_capability(input, EV_KEY, BTN_TOUCH); 315 input_set_abs_params(input, ABS_X, 0, VF_ADC_MAX, 0, 0); 316 input_set_abs_params(input, ABS_Y, 0, VF_ADC_MAX, 0, 0); 317 input_set_abs_params(input, ABS_PRESSURE, 0, VF_ADC_MAX, 0, 0); 318 319 touchdev->ts_input = input; 320 input_set_drvdata(input, touchdev); 321 322 error = input_register_device(input); 323 if (error) { 324 dev_err(dev, "Failed to register input device\n"); 325 return error; 326 } 327 328 error = vf50_ts_get_gpiod(dev, &touchdev->gpio_xp, "xp", GPIOD_OUT_LOW); 329 if (error) 330 return error; 331 332 error = vf50_ts_get_gpiod(dev, &touchdev->gpio_xm, 333 "xm", GPIOD_OUT_LOW); 334 if (error) 335 return error; 336 337 error = vf50_ts_get_gpiod(dev, &touchdev->gpio_yp, "yp", GPIOD_OUT_LOW); 338 if (error) 339 return error; 340 341 error = vf50_ts_get_gpiod(dev, &touchdev->gpio_ym, "ym", GPIOD_OUT_LOW); 342 if (error) 343 return error; 344 345 touchdev->pen_irq = platform_get_irq(pdev, 0); 346 if (touchdev->pen_irq < 0) 347 return touchdev->pen_irq; 348 349 error = devm_request_threaded_irq(dev, touchdev->pen_irq, 350 NULL, vf50_ts_irq_bh, IRQF_ONESHOT, 351 "vf50 touch", touchdev); 352 if (error) { 353 dev_err(dev, "Failed to request IRQ %d: %d\n", 354 touchdev->pen_irq, error); 355 return error; 356 } 357 358 return 0; 359 } 360 361 static const struct of_device_id vf50_touch_of_match[] = { 362 { .compatible = "toradex,vf50-touchscreen", }, 363 { } 364 }; 365 MODULE_DEVICE_TABLE(of, vf50_touch_of_match); 366 367 static struct platform_driver vf50_touch_driver = { 368 .driver = { 369 .name = "toradex,vf50_touchctrl", 370 .of_match_table = vf50_touch_of_match, 371 }, 372 .probe = vf50_ts_probe, 373 }; 374 module_platform_driver(vf50_touch_driver); 375 376 MODULE_AUTHOR("Sanchayan Maity"); 377 MODULE_DESCRIPTION("Colibri VF50 Touchscreen driver"); 378 MODULE_LICENSE("GPL"); 379