drivers/input/touchscreen/tsc2007_core.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * drivers/input/touchscreen/tsc2007.c
   4  *
   5  * Copyright (c) 2008 MtekVision Co., Ltd.
   6  *      Kwangwoo Lee <kwlee@mtekvision.com>
   7  *
   8  * Using code from:
   9  *  - ads7846.c
  10  *      Copyright (c) 2005 David Brownell
  11  *      Copyright (c) 2006 Nokia Corporation
  12  *  - corgi_ts.c
  13  *      Copyright (C) 2004-2005 Richard Purdie
  14  *  - omap_ts.[hc], ads7846.h, ts_osk.c
  15  *      Copyright (C) 2002 MontaVista Software
  16  *      Copyright (C) 2004 Texas Instruments
  17  *      Copyright (C) 2005 Dirk Behme
  18  */
  19
  20 #include <linux/module.h>
  21 #include <linux/slab.h>
  22 #include <linux/gpio/consumer.h>
  23 #include <linux/input.h>
  24 #include <linux/interrupt.h>
  25 #include <linux/i2c.h>
  26 #include <linux/mod_devicetable.h>
  27 #include <linux/property.h>
  28 #include <linux/platform_data/tsc2007.h>
  29 #include "tsc2007.h"
  30
  31 int tsc2007_xfer(struct tsc2007 *tsc, u8 cmd)
  32 {
  33         s32 data;
  34         u16 val;
  35
  36         data = i2c_smbus_read_word_data(tsc->client, cmd);
  37         if (data < 0) {
  38                 dev_err(&tsc->client->dev, "i2c io error: %d\n", data);
  39                 return data;
  40         }
  41
  42         /* The protocol and raw data format from i2c interface:
  43          * S Addr Wr [A] Comm [A] S Addr Rd [A] [DataLow] A [DataHigh] NA P
  44          * Where DataLow has [D11-D4], DataHigh has [D3-D0 << 4 | Dummy 4bit].
  45          */
  46         val = swab16(data) >> 4;
  47
  48         dev_dbg(&tsc->client->dev, "data: 0x%x, val: 0x%x\n", data, val);
  49
  50         return val;
  51 }
  52
  53 static void tsc2007_read_values(struct tsc2007 *tsc, struct ts_event *tc)
  54 {
  55         /* y- still on; turn on only y+ (and ADC) */
  56         tc->y = tsc2007_xfer(tsc, READ_Y);
  57
  58         /* turn y- off, x+ on, then leave in lowpower */
  59         tc->x = tsc2007_xfer(tsc, READ_X);
  60
  61         /* turn y+ off, x- on; we'll use formula #1 */
  62         tc->z1 = tsc2007_xfer(tsc, READ_Z1);
  63         tc->z2 = tsc2007_xfer(tsc, READ_Z2);
  64
  65         /* Prepare for next touch reading - power down ADC, enable PENIRQ */
  66         tsc2007_xfer(tsc, PWRDOWN);
  67 }
  68
  69 u32 tsc2007_calculate_resistance(struct tsc2007 *tsc, struct ts_event *tc)
  70 {
  71         u32 rt = 0;
  72
  73         /* range filtering */
  74         if (tc->x == MAX_12BIT)
  75                 tc->x = 0;
  76
  77         if (likely(tc->x && tc->z1)) {
  78                 /* compute touch resistance using equation #1 */
  79                 rt = tc->z2 - tc->z1;
  80                 rt *= tc->x;
  81                 rt *= tsc->x_plate_ohms;
  82                 rt /= tc->z1;
  83                 rt = (rt + 2047) >> 12;
  84         }
  85
  86         return rt;
  87 }
  88
  89 bool tsc2007_is_pen_down(struct tsc2007 *ts)
  90 {
  91         /*
  92          * NOTE: We can't rely on the pressure to determine the pen down
  93          * state, even though this controller has a pressure sensor.
  94          * The pressure value can fluctuate for quite a while after
  95          * lifting the pen and in some cases may not even settle at the
  96          * expected value.
  97          *
  98          * The only safe way to check for the pen up condition is in the
  99          * work function by reading the pen signal state (it's a GPIO
 100          * and IRQ). Unfortunately such callback is not always available,
 101          * in that case we assume that the pen is down and expect caller
 102          * to fall back on the pressure reading.
 103          */
 104
 105         if (!ts->get_pendown_state)
 106                 return true;
 107
 108         return ts->get_pendown_state(&ts->client->dev);
 109 }
 110
 111 static irqreturn_t tsc2007_soft_irq(int irq, void *handle)
 112 {
 113         struct tsc2007 *ts = handle;
 114         struct input_dev *input = ts->input;
 115         struct ts_event tc;
 116         u32 rt;
 117
 118         while (!ts->stopped && tsc2007_is_pen_down(ts)) {
 119
 120                 /* pen is down, continue with the measurement */
 121
 122                 mutex_lock(&ts->mlock);
 123                 tsc2007_read_values(ts, &tc);
 124                 mutex_unlock(&ts->mlock);
 125
 126                 rt = tsc2007_calculate_resistance(ts, &tc);
 127
 128                 if (!rt && !ts->get_pendown_state) {
 129                         /*
 130                          * If pressure reported is 0 and we don't have
 131                          * callback to check pendown state, we have to
 132                          * assume that pen was lifted up.
 133                          */
 134                         break;
 135                 }
 136
 137                 if (rt <= ts->max_rt) {
 138                         dev_dbg(&ts->client->dev,
 139                                 "DOWN point(%4d,%4d), resistance (%4u)\n",
 140                                 tc.x, tc.y, rt);
 141
 142                         rt = ts->max_rt - rt;
 143
 144                         input_report_key(input, BTN_TOUCH, 1);
 145                         input_report_abs(input, ABS_X, tc.x);
 146                         input_report_abs(input, ABS_Y, tc.y);
 147                         input_report_abs(input, ABS_PRESSURE, rt);
 148
 149                         input_sync(input);
 150
 151                 } else {
 152                         /*
 153                          * Sample found inconsistent by debouncing or pressure is
 154                          * beyond the maximum. Don't report it to user space,
 155                          * repeat at least once more the measurement.
 156                          */
 157                         dev_dbg(&ts->client->dev, "ignored pressure %d\n", rt);
 158                 }
 159
 160                 wait_event_timeout(ts->wait, ts->stopped, ts->poll_period);
 161         }
 162
 163         dev_dbg(&ts->client->dev, "UP\n");
 164
 165         input_report_key(input, BTN_TOUCH, 0);
 166         input_report_abs(input, ABS_PRESSURE, 0);
 167         input_sync(input);
 168
 169         if (ts->clear_penirq)
 170                 ts->clear_penirq();
 171
 172         return IRQ_HANDLED;
 173 }
 174
 175 static irqreturn_t tsc2007_hard_irq(int irq, void *handle)
 176 {
 177         struct tsc2007 *ts = handle;
 178
 179         if (tsc2007_is_pen_down(ts))
 180                 return IRQ_WAKE_THREAD;
 181
 182         if (ts->clear_penirq)
 183                 ts->clear_penirq();
 184
 185         return IRQ_HANDLED;
 186 }
 187
 188 static void tsc2007_stop(struct tsc2007 *ts)
 189 {
 190         ts->stopped = true;
 191         mb();
 192         wake_up(&ts->wait);
 193
 194         disable_irq(ts->irq);
 195 }
 196
 197 static int tsc2007_open(struct input_dev *input_dev)
 198 {
 199         struct tsc2007 *ts = input_get_drvdata(input_dev);
 200         int err;
 201
 202         ts->stopped = false;
 203         mb();
 204
 205         enable_irq(ts->irq);
 206
 207         /* Prepare for touch readings - power down ADC and enable PENIRQ */
 208         err = tsc2007_xfer(ts, PWRDOWN);
 209         if (err < 0) {
 210                 tsc2007_stop(ts);
 211                 return err;
 212         }
 213
 214         return 0;
 215 }
 216
 217 static void tsc2007_close(struct input_dev *input_dev)
 218 {
 219         struct tsc2007 *ts = input_get_drvdata(input_dev);
 220
 221         tsc2007_stop(ts);
 222 }
 223
 224 static int tsc2007_get_pendown_state_gpio(struct device *dev)
 225 {
 226         struct i2c_client *client = to_i2c_client(dev);
 227         struct tsc2007 *ts = i2c_get_clientdata(client);
 228
 229         return gpiod_get_value(ts->gpiod);
 230 }
 231
 232 static int tsc2007_probe_properties(struct device *dev, struct tsc2007 *ts)
 233 {
 234         u32 val32;
 235         u64 val64;
 236
 237         if (!device_property_read_u32(dev, "ti,max-rt", &val32))
 238                 ts->max_rt = val32;
 239         else
 240                 ts->max_rt = MAX_12BIT;
 241
 242         if (!device_property_read_u32(dev, "ti,fuzzx", &val32))
 243                 ts->fuzzx = val32;
 244
 245         if (!device_property_read_u32(dev, "ti,fuzzy", &val32))
 246                 ts->fuzzy = val32;
 247
 248         if (!device_property_read_u32(dev, "ti,fuzzz", &val32))
 249                 ts->fuzzz = val32;
 250
 251         if (!device_property_read_u64(dev, "ti,poll-period", &val64))
 252                 ts->poll_period = msecs_to_jiffies(val64);
 253         else
 254                 ts->poll_period = msecs_to_jiffies(1);
 255
 256         if (!device_property_read_u32(dev, "ti,x-plate-ohms", &val32)) {
 257                 ts->x_plate_ohms = val32;
 258         } else {
 259                 dev_err(dev, "Missing ti,x-plate-ohms device property\n");
 260                 return -EINVAL;
 261         }
 262
 263         ts->gpiod = devm_gpiod_get_optional(dev, NULL, GPIOD_IN);
 264         if (IS_ERR(ts->gpiod))
 265                 return PTR_ERR(ts->gpiod);
 266
 267         if (ts->gpiod)
 268                 ts->get_pendown_state = tsc2007_get_pendown_state_gpio;
 269         else
 270                 dev_warn(dev, "Pen down GPIO is not specified in properties\n");
 271
 272         return 0;
 273 }
 274
 275 static int tsc2007_probe_pdev(struct device *dev, struct tsc2007 *ts,
 276                               const struct tsc2007_platform_data *pdata,
 277                               const struct i2c_device_id *id)
 278 {
 279         ts->model             = pdata->model;
 280         ts->x_plate_ohms      = pdata->x_plate_ohms;
 281         ts->max_rt            = pdata->max_rt ? : MAX_12BIT;
 282         ts->poll_period       = msecs_to_jiffies(pdata->poll_period ? : 1);
 283         ts->get_pendown_state = pdata->get_pendown_state;
 284         ts->clear_penirq      = pdata->clear_penirq;
 285         ts->fuzzx             = pdata->fuzzx;
 286         ts->fuzzy             = pdata->fuzzy;
 287         ts->fuzzz             = pdata->fuzzz;
 288
 289         if (pdata->x_plate_ohms == 0) {
 290                 dev_err(dev, "x_plate_ohms is not set up in platform data\n");
 291                 return -EINVAL;
 292         }
 293
 294         return 0;
 295 }
 296
 297 static void tsc2007_call_exit_platform_hw(void *data)
 298 {
 299         struct device *dev = data;
 300         const struct tsc2007_platform_data *pdata = dev_get_platdata(dev);
 301
 302         pdata->exit_platform_hw();
 303 }
 304
 305 static int tsc2007_probe(struct i2c_client *client,
 306                          const struct i2c_device_id *id)
 307 {
 308         const struct tsc2007_platform_data *pdata =
 309                 dev_get_platdata(&client->dev);
 310         struct tsc2007 *ts;
 311         struct input_dev *input_dev;
 312         int err;
 313
 314         if (!i2c_check_functionality(client->adapter,
 315                                      I2C_FUNC_SMBUS_READ_WORD_DATA))
 316                 return -EIO;
 317
 318         ts = devm_kzalloc(&client->dev, sizeof(struct tsc2007), GFP_KERNEL);
 319         if (!ts)
 320                 return -ENOMEM;
 321
 322         if (pdata)
 323                 err = tsc2007_probe_pdev(&client->dev, ts, pdata, id);
 324         else
 325                 err = tsc2007_probe_properties(&client->dev, ts);
 326         if (err)
 327                 return err;
 328
 329         input_dev = devm_input_allocate_device(&client->dev);
 330         if (!input_dev)
 331                 return -ENOMEM;
 332
 333         i2c_set_clientdata(client, ts);
 334
 335         ts->client = client;
 336         ts->irq = client->irq;
 337         ts->input = input_dev;
 338
 339         init_waitqueue_head(&ts->wait);
 340         mutex_init(&ts->mlock);
 341
 342         snprintf(ts->phys, sizeof(ts->phys),
 343                  "%s/input0", dev_name(&client->dev));
 344
 345         input_dev->name = "TSC2007 Touchscreen";
 346         input_dev->phys = ts->phys;
 347         input_dev->id.bustype = BUS_I2C;
 348
 349         input_dev->open = tsc2007_open;
 350         input_dev->close = tsc2007_close;
 351
 352         input_set_drvdata(input_dev, ts);
 353
 354         input_set_capability(input_dev, EV_KEY, BTN_TOUCH);
 355
 356         input_set_abs_params(input_dev, ABS_X, 0, MAX_12BIT, ts->fuzzx, 0);
 357         input_set_abs_params(input_dev, ABS_Y, 0, MAX_12BIT, ts->fuzzy, 0);
 358         input_set_abs_params(input_dev, ABS_PRESSURE, 0, MAX_12BIT,
 359                              ts->fuzzz, 0);
 360
 361         if (pdata) {
 362                 if (pdata->exit_platform_hw) {
 363                         err = devm_add_action(&client->dev,
 364                                               tsc2007_call_exit_platform_hw,
 365                                               &client->dev);
 366                         if (err) {
 367                                 dev_err(&client->dev,
 368                                         "Failed to register exit_platform_hw action, %d\n",
 369                                         err);
 370                                 return err;
 371                         }
 372                 }
 373
 374                 if (pdata->init_platform_hw)
 375                         pdata->init_platform_hw();
 376         }
 377
 378         err = devm_request_threaded_irq(&client->dev, ts->irq,
 379                                         tsc2007_hard_irq, tsc2007_soft_irq,
 380                                         IRQF_ONESHOT,
 381                                         client->dev.driver->name, ts);
 382         if (err) {
 383                 dev_err(&client->dev, "Failed to request irq %d: %d\n",
 384                         ts->irq, err);
 385                 return err;
 386         }
 387
 388         tsc2007_stop(ts);
 389
 390         /* power down the chip (TSC2007_SETUP does not ACK on I2C) */
 391         err = tsc2007_xfer(ts, PWRDOWN);
 392         if (err < 0) {
 393                 dev_err(&client->dev,
 394                         "Failed to setup chip: %d\n", err);
 395                 return err;     /* chip does not respond */
 396         }
 397
 398         err = input_register_device(input_dev);
 399         if (err) {
 400                 dev_err(&client->dev,
 401                         "Failed to register input device: %d\n", err);
 402                 return err;
 403         }
 404
 405         err =  tsc2007_iio_configure(ts);
 406         if (err) {
 407                 dev_err(&client->dev,
 408                         "Failed to register with IIO: %d\n", err);
 409                 return err;
 410         }
 411
 412         return 0;
 413 }
 414
 415 static const struct i2c_device_id tsc2007_idtable[] = {
 416         { "tsc2007", 0 },
 417         { }
 418 };
 419
 420 MODULE_DEVICE_TABLE(i2c, tsc2007_idtable);
 421
 422 static const struct of_device_id tsc2007_of_match[] = {
 423         { .compatible = "ti,tsc2007" },
 424         { /* sentinel */ }
 425 };
 426 MODULE_DEVICE_TABLE(of, tsc2007_of_match);
 427
 428 static struct i2c_driver tsc2007_driver = {
 429         .driver = {
 430                 .name   = "tsc2007",
 431                 .of_match_table = tsc2007_of_match,
 432         },
 433         .id_table       = tsc2007_idtable,
 434         .probe          = tsc2007_probe,
 435 };
 436
 437 module_i2c_driver(tsc2007_driver);
 438
 439 MODULE_AUTHOR("Kwangwoo Lee <kwlee@mtekvision.com>");
 440 MODULE_DESCRIPTION("TSC2007 TouchScreen Driver");
 441 MODULE_LICENSE("GPL");