drivers/input/touchscreen/tsc2007.c

   1 /*
   2  * drivers/input/touchscreen/tsc2007.c
   3  *
   4  * Copyright (c) 2008 MtekVision Co., Ltd.
   5  *      Kwangwoo Lee <kwlee@mtekvision.com>
   6  *
   7  * Using code from:
   8  *  - ads7846.c
   9  *      Copyright (c) 2005 David Brownell
  10  *      Copyright (c) 2006 Nokia Corporation
  11  *  - corgi_ts.c
  12  *      Copyright (C) 2004-2005 Richard Purdie
  13  *  - omap_ts.[hc], ads7846.h, ts_osk.c
  14  *      Copyright (C) 2002 MontaVista Software
  15  *      Copyright (C) 2004 Texas Instruments
  16  *      Copyright (C) 2005 Dirk Behme
  17  *
  18  *  This program is free software; you can redistribute it and/or modify
  19  *  it under the terms of the GNU General Public License version 2 as
  20  *  published by the Free Software Foundation.
  21  */
  22
  23 #include <linux/module.h>
  24 #include <linux/slab.h>
  25 #include <linux/input.h>
  26 #include <linux/interrupt.h>
  27 #include <linux/i2c.h>
  28 #include <linux/i2c/tsc2007.h>
  29
  30 #define TS_POLL_DELAY                   1 /* ms delay between samples */
  31 #define TS_POLL_PERIOD                  1 /* ms delay between samples */
  32
  33 #define TSC2007_MEASURE_TEMP0           (0x0 << 4)
  34 #define TSC2007_MEASURE_AUX             (0x2 << 4)
  35 #define TSC2007_MEASURE_TEMP1           (0x4 << 4)
  36 #define TSC2007_ACTIVATE_XN             (0x8 << 4)
  37 #define TSC2007_ACTIVATE_YN             (0x9 << 4)
  38 #define TSC2007_ACTIVATE_YP_XN          (0xa << 4)
  39 #define TSC2007_SETUP                   (0xb << 4)
  40 #define TSC2007_MEASURE_X               (0xc << 4)
  41 #define TSC2007_MEASURE_Y               (0xd << 4)
  42 #define TSC2007_MEASURE_Z1              (0xe << 4)
  43 #define TSC2007_MEASURE_Z2              (0xf << 4)
  44
  45 #define TSC2007_POWER_OFF_IRQ_EN        (0x0 << 2)
  46 #define TSC2007_ADC_ON_IRQ_DIS0         (0x1 << 2)
  47 #define TSC2007_ADC_OFF_IRQ_EN          (0x2 << 2)
  48 #define TSC2007_ADC_ON_IRQ_DIS1         (0x3 << 2)
  49
  50 #define TSC2007_12BIT                   (0x0 << 1)
  51 #define TSC2007_8BIT                    (0x1 << 1)
  52
  53 #define MAX_12BIT                       ((1 << 12) - 1)
  54
  55 #define ADC_ON_12BIT    (TSC2007_12BIT | TSC2007_ADC_ON_IRQ_DIS0)
  56
  57 #define READ_Y          (ADC_ON_12BIT | TSC2007_MEASURE_Y)
  58 #define READ_Z1         (ADC_ON_12BIT | TSC2007_MEASURE_Z1)
  59 #define READ_Z2         (ADC_ON_12BIT | TSC2007_MEASURE_Z2)
  60 #define READ_X          (ADC_ON_12BIT | TSC2007_MEASURE_X)
  61 #define PWRDOWN         (TSC2007_12BIT | TSC2007_POWER_OFF_IRQ_EN)
  62
  63 struct ts_event {
  64         u16     x;
  65         u16     y;
  66         u16     z1, z2;
  67 };
  68
  69 struct tsc2007 {
  70         struct input_dev        *input;
  71         char                    phys[32];
  72         struct delayed_work     work;
  73
  74         struct i2c_client       *client;
  75
  76         u16                     model;
  77         u16                     x_plate_ohms;
  78         u16                     max_rt;
  79
  80         bool                    pendown;
  81         int                     irq;
  82
  83         int                     (*get_pendown_state)(void);
  84         void                    (*clear_penirq)(void);
  85 };
  86
  87 static inline int tsc2007_xfer(struct tsc2007 *tsc, u8 cmd)
  88 {
  89         s32 data;
  90         u16 val;
  91
  92         data = i2c_smbus_read_word_data(tsc->client, cmd);
  93         if (data < 0) {
  94                 dev_err(&tsc->client->dev, "i2c io error: %d\n", data);
  95                 return data;
  96         }
  97
  98         /* The protocol and raw data format from i2c interface:
  99          * S Addr Wr [A] Comm [A] S Addr Rd [A] [DataLow] A [DataHigh] NA P
 100          * Where DataLow has [D11-D4], DataHigh has [D3-D0 << 4 | Dummy 4bit].
 101          */
 102         val = swab16(data) >> 4;
 103
 104         dev_dbg(&tsc->client->dev, "data: 0x%x, val: 0x%x\n", data, val);
 105
 106         return val;
 107 }
 108
 109 static void tsc2007_read_values(struct tsc2007 *tsc, struct ts_event *tc)
 110 {
 111         /* y- still on; turn on only y+ (and ADC) */
 112         tc->y = tsc2007_xfer(tsc, READ_Y);
 113
 114         /* turn y- off, x+ on, then leave in lowpower */
 115         tc->x = tsc2007_xfer(tsc, READ_X);
 116
 117         /* turn y+ off, x- on; we'll use formula #1 */
 118         tc->z1 = tsc2007_xfer(tsc, READ_Z1);
 119         tc->z2 = tsc2007_xfer(tsc, READ_Z2);
 120
 121         /* Prepare for next touch reading - power down ADC, enable PENIRQ */
 122         tsc2007_xfer(tsc, PWRDOWN);
 123 }
 124
 125 static u32 tsc2007_calculate_pressure(struct tsc2007 *tsc, struct ts_event *tc)
 126 {
 127         u32 rt = 0;
 128
 129         /* range filtering */
 130         if (tc->x == MAX_12BIT)
 131                 tc->x = 0;
 132
 133         if (likely(tc->x && tc->z1)) {
 134                 /* compute touch pressure resistance using equation #1 */
 135                 rt = tc->z2 - tc->z1;
 136                 rt *= tc->x;
 137                 rt *= tsc->x_plate_ohms;
 138                 rt /= tc->z1;
 139                 rt = (rt + 2047) >> 12;
 140         }
 141
 142         return rt;
 143 }
 144
 145 static void tsc2007_send_up_event(struct tsc2007 *tsc)
 146 {
 147         struct input_dev *input = tsc->input;
 148
 149         dev_dbg(&tsc->client->dev, "UP\n");
 150
 151         input_report_key(input, BTN_TOUCH, 0);
 152         input_report_abs(input, ABS_PRESSURE, 0);
 153         input_sync(input);
 154 }
 155
 156 static void tsc2007_work(struct work_struct *work)
 157 {
 158         struct tsc2007 *ts =
 159                 container_of(to_delayed_work(work), struct tsc2007, work);
 160         bool debounced = false;
 161         struct ts_event tc;
 162         u32 rt;
 163
 164         /*
 165          * NOTE: We can't rely on the pressure to determine the pen down
 166          * state, even though this controller has a pressure sensor.
 167          * The pressure value can fluctuate for quite a while after
 168          * lifting the pen and in some cases may not even settle at the
 169          * expected value.
 170          *
 171          * The only safe way to check for the pen up condition is in the
 172          * work function by reading the pen signal state (it's a GPIO
 173          * and IRQ). Unfortunately such callback is not always available,
 174          * in that case we have rely on the pressure anyway.
 175          */
 176         if (ts->get_pendown_state) {
 177                 if (unlikely(!ts->get_pendown_state())) {
 178                         tsc2007_send_up_event(ts);
 179                         ts->pendown = false;
 180                         goto out;
 181                 }
 182
 183                 dev_dbg(&ts->client->dev, "pen is still down\n");
 184         }
 185
 186         tsc2007_read_values(ts, &tc);
 187
 188         rt = tsc2007_calculate_pressure(ts, &tc);
 189         if (rt > ts->max_rt) {
 190                 /*
 191                  * Sample found inconsistent by debouncing or pressure is
 192                  * beyond the maximum. Don't report it to user space,
 193                  * repeat at least once more the measurement.
 194                  */
 195                 dev_dbg(&ts->client->dev, "ignored pressure %d\n", rt);
 196                 debounced = true;
 197                 goto out;
 198
 199         }
 200
 201         if (rt) {
 202                 struct input_dev *input = ts->input;
 203
 204                 if (!ts->pendown) {
 205                         dev_dbg(&ts->client->dev, "DOWN\n");
 206
 207                         input_report_key(input, BTN_TOUCH, 1);
 208                         ts->pendown = true;
 209                 }
 210
 211                 input_report_abs(input, ABS_X, tc.x);
 212                 input_report_abs(input, ABS_Y, tc.y);
 213                 input_report_abs(input, ABS_PRESSURE, rt);
 214
 215                 input_sync(input);
 216
 217                 dev_dbg(&ts->client->dev, "point(%4d,%4d), pressure (%4u)\n",
 218                         tc.x, tc.y, rt);
 219
 220         } else if (!ts->get_pendown_state && ts->pendown) {
 221                 /*
 222                  * We don't have callback to check pendown state, so we
 223                  * have to assume that since pressure reported is 0 the
 224                  * pen was lifted up.
 225                  */
 226                 tsc2007_send_up_event(ts);
 227                 ts->pendown = false;
 228         }
 229
 230  out:
 231         if (ts->pendown || debounced)
 232                 schedule_delayed_work(&ts->work,
 233                                       msecs_to_jiffies(TS_POLL_PERIOD));
 234         else
 235                 enable_irq(ts->irq);
 236 }
 237
 238 static irqreturn_t tsc2007_irq(int irq, void *handle)
 239 {
 240         struct tsc2007 *ts = handle;
 241
 242         if (!ts->get_pendown_state || likely(ts->get_pendown_state())) {
 243                 disable_irq_nosync(ts->irq);
 244                 schedule_delayed_work(&ts->work,
 245                                       msecs_to_jiffies(TS_POLL_DELAY));
 246         }
 247
 248         if (ts->clear_penirq)
 249                 ts->clear_penirq();
 250
 251         return IRQ_HANDLED;
 252 }
 253
 254 static void tsc2007_free_irq(struct tsc2007 *ts)
 255 {
 256         free_irq(ts->irq, ts);
 257         if (cancel_delayed_work_sync(&ts->work)) {
 258                 /*
 259                  * Work was pending, therefore we need to enable
 260                  * IRQ here to balance the disable_irq() done in the
 261                  * interrupt handler.
 262                  */
 263                 enable_irq(ts->irq);
 264         }
 265 }
 266
 267 static int __devinit tsc2007_probe(struct i2c_client *client,
 268                                    const struct i2c_device_id *id)
 269 {
 270         struct tsc2007 *ts;
 271         struct tsc2007_platform_data *pdata = client->dev.platform_data;
 272         struct input_dev *input_dev;
 273         int err;
 274
 275         if (!pdata) {
 276                 dev_err(&client->dev, "platform data is required!\n");
 277                 return -EINVAL;
 278         }
 279
 280         if (!i2c_check_functionality(client->adapter,
 281                                      I2C_FUNC_SMBUS_READ_WORD_DATA))
 282                 return -EIO;
 283
 284         ts = kzalloc(sizeof(struct tsc2007), GFP_KERNEL);
 285         input_dev = input_allocate_device();
 286         if (!ts || !input_dev) {
 287                 err = -ENOMEM;
 288                 goto err_free_mem;
 289         }
 290
 291         ts->client = client;
 292         ts->irq = client->irq;
 293         ts->input = input_dev;
 294         INIT_DELAYED_WORK(&ts->work, tsc2007_work);
 295
 296         ts->model             = pdata->model;
 297         ts->x_plate_ohms      = pdata->x_plate_ohms;
 298         ts->max_rt            = pdata->max_rt ? : MAX_12BIT;
 299         ts->get_pendown_state = pdata->get_pendown_state;
 300         ts->clear_penirq      = pdata->clear_penirq;
 301
 302         snprintf(ts->phys, sizeof(ts->phys),
 303                  "%s/input0", dev_name(&client->dev));
 304
 305         input_dev->name = "TSC2007 Touchscreen";
 306         input_dev->phys = ts->phys;
 307         input_dev->id.bustype = BUS_I2C;
 308
 309         input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
 310         input_dev->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH);
 311
 312         input_set_abs_params(input_dev, ABS_X, 0, MAX_12BIT, 0, 0);
 313         input_set_abs_params(input_dev, ABS_Y, 0, MAX_12BIT, 0, 0);
 314         input_set_abs_params(input_dev, ABS_PRESSURE, 0, MAX_12BIT, 0, 0);
 315
 316         if (pdata->init_platform_hw)
 317                 pdata->init_platform_hw();
 318
 319         err = request_irq(ts->irq, tsc2007_irq, 0,
 320                         client->dev.driver->name, ts);
 321         if (err < 0) {
 322                 dev_err(&client->dev, "irq %d busy?\n", ts->irq);
 323                 goto err_free_mem;
 324         }
 325
 326         /* Prepare for touch readings - power down ADC and enable PENIRQ */
 327         err = tsc2007_xfer(ts, PWRDOWN);
 328         if (err < 0)
 329                 goto err_free_irq;
 330
 331         err = input_register_device(input_dev);
 332         if (err)
 333                 goto err_free_irq;
 334
 335         i2c_set_clientdata(client, ts);
 336
 337         return 0;
 338
 339  err_free_irq:
 340         tsc2007_free_irq(ts);
 341         if (pdata->exit_platform_hw)
 342                 pdata->exit_platform_hw();
 343  err_free_mem:
 344         input_free_device(input_dev);
 345         kfree(ts);
 346         return err;
 347 }
 348
 349 static int __devexit tsc2007_remove(struct i2c_client *client)
 350 {
 351         struct tsc2007  *ts = i2c_get_clientdata(client);
 352         struct tsc2007_platform_data *pdata = client->dev.platform_data;
 353
 354         tsc2007_free_irq(ts);
 355
 356         if (pdata->exit_platform_hw)
 357                 pdata->exit_platform_hw();
 358
 359         input_unregister_device(ts->input);
 360         kfree(ts);
 361
 362         return 0;
 363 }
 364
 365 static const struct i2c_device_id tsc2007_idtable[] = {
 366         { "tsc2007", 0 },
 367         { }
 368 };
 369
 370 MODULE_DEVICE_TABLE(i2c, tsc2007_idtable);
 371
 372 static struct i2c_driver tsc2007_driver = {
 373         .driver = {
 374                 .owner  = THIS_MODULE,
 375                 .name   = "tsc2007"
 376         },
 377         .id_table       = tsc2007_idtable,
 378         .probe          = tsc2007_probe,
 379         .remove         = __devexit_p(tsc2007_remove),
 380 };
 381
 382 static int __init tsc2007_init(void)
 383 {
 384         return i2c_add_driver(&tsc2007_driver);
 385 }
 386
 387 static void __exit tsc2007_exit(void)
 388 {
 389         i2c_del_driver(&tsc2007_driver);
 390 }
 391
 392 module_init(tsc2007_init);
 393 module_exit(tsc2007_exit);
 394
 395 MODULE_AUTHOR("Kwangwoo Lee <kwlee@mtekvision.com>");
 396 MODULE_DESCRIPTION("TSC2007 TouchScreen Driver");
 397 MODULE_LICENSE("GPL");