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 void tsc2007_stop(struct tsc2007 *ts)
 176 {
 177         ts->stopped = true;
 178         mb();
 179         wake_up(&ts->wait);
 180
 181         disable_irq(ts->irq);
 182 }
 183
 184 static int tsc2007_open(struct input_dev *input_dev)
 185 {
 186         struct tsc2007 *ts = input_get_drvdata(input_dev);
 187         int err;
 188
 189         ts->stopped = false;
 190         mb();
 191
 192         enable_irq(ts->irq);
 193
 194         /* Prepare for touch readings - power down ADC and enable PENIRQ */
 195         err = tsc2007_xfer(ts, PWRDOWN);
 196         if (err < 0) {
 197                 tsc2007_stop(ts);
 198                 return err;
 199         }
 200
 201         return 0;
 202 }
 203
 204 static void tsc2007_close(struct input_dev *input_dev)
 205 {
 206         struct tsc2007 *ts = input_get_drvdata(input_dev);
 207
 208         tsc2007_stop(ts);
 209 }
 210
 211 static int tsc2007_get_pendown_state_gpio(struct device *dev)
 212 {
 213         struct i2c_client *client = to_i2c_client(dev);
 214         struct tsc2007 *ts = i2c_get_clientdata(client);
 215
 216         return gpiod_get_value_cansleep(ts->gpiod);
 217 }
 218
 219 static int tsc2007_probe_properties(struct device *dev, struct tsc2007 *ts)
 220 {
 221         u32 val32;
 222         u64 val64;
 223
 224         if (!device_property_read_u32(dev, "ti,max-rt", &val32))
 225                 ts->max_rt = val32;
 226         else
 227                 ts->max_rt = MAX_12BIT;
 228
 229         if (!device_property_read_u32(dev, "ti,fuzzx", &val32))
 230                 ts->fuzzx = val32;
 231
 232         if (!device_property_read_u32(dev, "ti,fuzzy", &val32))
 233                 ts->fuzzy = val32;
 234
 235         if (!device_property_read_u32(dev, "ti,fuzzz", &val32))
 236                 ts->fuzzz = val32;
 237
 238         if (!device_property_read_u64(dev, "ti,poll-period", &val64))
 239                 ts->poll_period = msecs_to_jiffies(val64);
 240         else
 241                 ts->poll_period = msecs_to_jiffies(1);
 242
 243         if (!device_property_read_u32(dev, "ti,x-plate-ohms", &val32)) {
 244                 ts->x_plate_ohms = val32;
 245         } else {
 246                 dev_err(dev, "Missing ti,x-plate-ohms device property\n");
 247                 return -EINVAL;
 248         }
 249
 250         ts->gpiod = devm_gpiod_get_optional(dev, NULL, GPIOD_IN);
 251         if (IS_ERR(ts->gpiod))
 252                 return PTR_ERR(ts->gpiod);
 253
 254         if (ts->gpiod)
 255                 ts->get_pendown_state = tsc2007_get_pendown_state_gpio;
 256         else
 257                 dev_warn(dev, "Pen down GPIO is not specified in properties\n");
 258
 259         return 0;
 260 }
 261
 262 static int tsc2007_probe_pdev(struct device *dev, struct tsc2007 *ts,
 263                               const struct tsc2007_platform_data *pdata,
 264                               const struct i2c_device_id *id)
 265 {
 266         ts->model             = pdata->model;
 267         ts->x_plate_ohms      = pdata->x_plate_ohms;
 268         ts->max_rt            = pdata->max_rt ? : MAX_12BIT;
 269         ts->poll_period       = msecs_to_jiffies(pdata->poll_period ? : 1);
 270         ts->get_pendown_state = pdata->get_pendown_state;
 271         ts->clear_penirq      = pdata->clear_penirq;
 272         ts->fuzzx             = pdata->fuzzx;
 273         ts->fuzzy             = pdata->fuzzy;
 274         ts->fuzzz             = pdata->fuzzz;
 275
 276         if (pdata->x_plate_ohms == 0) {
 277                 dev_err(dev, "x_plate_ohms is not set up in platform data\n");
 278                 return -EINVAL;
 279         }
 280
 281         return 0;
 282 }
 283
 284 static void tsc2007_call_exit_platform_hw(void *data)
 285 {
 286         struct device *dev = data;
 287         const struct tsc2007_platform_data *pdata = dev_get_platdata(dev);
 288
 289         pdata->exit_platform_hw();
 290 }
 291
 292 static int tsc2007_probe(struct i2c_client *client)
 293 {
 294         const struct i2c_device_id *id = i2c_client_get_device_id(client);
 295         const struct tsc2007_platform_data *pdata =
 296                 dev_get_platdata(&client->dev);
 297         struct tsc2007 *ts;
 298         struct input_dev *input_dev;
 299         int err;
 300
 301         if (!i2c_check_functionality(client->adapter,
 302                                      I2C_FUNC_SMBUS_READ_WORD_DATA))
 303                 return -EIO;
 304
 305         ts = devm_kzalloc(&client->dev, sizeof(struct tsc2007), GFP_KERNEL);
 306         if (!ts)
 307                 return -ENOMEM;
 308
 309         if (pdata)
 310                 err = tsc2007_probe_pdev(&client->dev, ts, pdata, id);
 311         else
 312                 err = tsc2007_probe_properties(&client->dev, ts);
 313         if (err)
 314                 return err;
 315
 316         input_dev = devm_input_allocate_device(&client->dev);
 317         if (!input_dev)
 318                 return -ENOMEM;
 319
 320         i2c_set_clientdata(client, ts);
 321
 322         ts->client = client;
 323         ts->irq = client->irq;
 324         ts->input = input_dev;
 325
 326         init_waitqueue_head(&ts->wait);
 327         mutex_init(&ts->mlock);
 328
 329         snprintf(ts->phys, sizeof(ts->phys),
 330                  "%s/input0", dev_name(&client->dev));
 331
 332         input_dev->name = "TSC2007 Touchscreen";
 333         input_dev->phys = ts->phys;
 334         input_dev->id.bustype = BUS_I2C;
 335
 336         input_dev->open = tsc2007_open;
 337         input_dev->close = tsc2007_close;
 338
 339         input_set_drvdata(input_dev, ts);
 340
 341         input_set_capability(input_dev, EV_KEY, BTN_TOUCH);
 342
 343         input_set_abs_params(input_dev, ABS_X, 0, MAX_12BIT, ts->fuzzx, 0);
 344         input_set_abs_params(input_dev, ABS_Y, 0, MAX_12BIT, ts->fuzzy, 0);
 345         input_set_abs_params(input_dev, ABS_PRESSURE, 0, MAX_12BIT,
 346                              ts->fuzzz, 0);
 347
 348         if (pdata) {
 349                 if (pdata->exit_platform_hw) {
 350                         err = devm_add_action(&client->dev,
 351                                               tsc2007_call_exit_platform_hw,
 352                                               &client->dev);
 353                         if (err) {
 354                                 dev_err(&client->dev,
 355                                         "Failed to register exit_platform_hw action, %d\n",
 356                                         err);
 357                                 return err;
 358                         }
 359                 }
 360
 361                 if (pdata->init_platform_hw)
 362                         pdata->init_platform_hw();
 363         }
 364
 365         err = devm_request_threaded_irq(&client->dev, ts->irq,
 366                                         NULL, tsc2007_soft_irq,
 367                                         IRQF_ONESHOT,
 368                                         client->dev.driver->name, ts);
 369         if (err) {
 370                 dev_err(&client->dev, "Failed to request irq %d: %d\n",
 371                         ts->irq, err);
 372                 return err;
 373         }
 374
 375         tsc2007_stop(ts);
 376
 377         /* power down the chip (TSC2007_SETUP does not ACK on I2C) */
 378         err = tsc2007_xfer(ts, PWRDOWN);
 379         if (err < 0) {
 380                 dev_err(&client->dev,
 381                         "Failed to setup chip: %d\n", err);
 382                 return err;     /* chip does not respond */
 383         }
 384
 385         err = input_register_device(input_dev);
 386         if (err) {
 387                 dev_err(&client->dev,
 388                         "Failed to register input device: %d\n", err);
 389                 return err;
 390         }
 391
 392         err =  tsc2007_iio_configure(ts);
 393         if (err) {
 394                 dev_err(&client->dev,
 395                         "Failed to register with IIO: %d\n", err);
 396                 return err;
 397         }
 398
 399         return 0;
 400 }
 401
 402 static const struct i2c_device_id tsc2007_idtable[] = {
 403         { "tsc2007" },
 404         { }
 405 };
 406
 407 MODULE_DEVICE_TABLE(i2c, tsc2007_idtable);
 408
 409 static const struct of_device_id tsc2007_of_match[] = {
 410         { .compatible = "ti,tsc2007" },
 411         { /* sentinel */ }
 412 };
 413 MODULE_DEVICE_TABLE(of, tsc2007_of_match);
 414
 415 static struct i2c_driver tsc2007_driver = {
 416         .driver = {
 417                 .name   = "tsc2007",
 418                 .of_match_table = tsc2007_of_match,
 419         },
 420         .id_table       = tsc2007_idtable,
 421         .probe          = tsc2007_probe,
 422 };
 423
 424 module_i2c_driver(tsc2007_driver);
 425
 426 MODULE_AUTHOR("Kwangwoo Lee <kwlee@mtekvision.com>");
 427 MODULE_DESCRIPTION("TSC2007 TouchScreen Driver");
 428 MODULE_LICENSE("GPL");