drivers/input/touchscreen/wm9705.c

   1 /*
   2  * wm9705.c  --  Codec driver for Wolfson WM9705 AC97 Codec.
   3  *
   4  * Copyright 2003, 2004, 2005, 2006, 2007 Wolfson Microelectronics PLC.
   5  * Author: Liam Girdwood
   6  *         liam.girdwood@wolfsonmicro.com or linux@wolfsonmicro.com
   7  * Parts Copyright : Ian Molton <spyro@f2s.com>
   8  *                   Andrew Zabolotny <zap@homelink.ru>
   9  *                   Russell King <rmk@arm.linux.org.uk>
  10  *
  11  *  This program is free software; you can redistribute  it and/or modify it
  12  *  under  the terms of  the GNU General  Public License as published by the
  13  *  Free Software Foundation;  either version 2 of the  License, or (at your
  14  *  option) any later version.
  15  *
  16  */
  17
  18 #include <linux/module.h>
  19 #include <linux/moduleparam.h>
  20 #include <linux/version.h>
  21 #include <linux/kernel.h>
  22 #include <linux/input.h>
  23 #include <linux/delay.h>
  24 #include <linux/bitops.h>
  25 #include <linux/wm97xx.h>
  26
  27 #define TS_NAME                 "wm97xx"
  28 #define WM9705_VERSION          "1.00"
  29 #define DEFAULT_PRESSURE        0xb0c0
  30
  31 /*
  32  * Module parameters
  33  */
  34
  35 /*
  36  * Set current used for pressure measurement.
  37  *
  38  * Set pil = 2 to use 400uA
  39  *     pil = 1 to use 200uA and
  40  *     pil = 0 to disable pressure measurement.
  41  *
  42  * This is used to increase the range of values returned by the adc
  43  * when measureing touchpanel pressure.
  44  */
  45 static int pil;
  46 module_param(pil, int, 0);
  47 MODULE_PARM_DESC(pil, "Set current used for pressure measurement.");
  48
  49 /*
  50  * Set threshold for pressure measurement.
  51  *
  52  * Pen down pressure below threshold is ignored.
  53  */
  54 static int pressure = DEFAULT_PRESSURE & 0xfff;
  55 module_param(pressure, int, 0);
  56 MODULE_PARM_DESC(pressure, "Set threshold for pressure measurement.");
  57
  58 /*
  59  * Set adc sample delay.
  60  *
  61  * For accurate touchpanel measurements, some settling time may be
  62  * required between the switch matrix applying a voltage across the
  63  * touchpanel plate and the ADC sampling the signal.
  64  *
  65  * This delay can be set by setting delay = n, where n is the array
  66  * position of the delay in the array delay_table below.
  67  * Long delays > 1ms are supported for completeness, but are not
  68  * recommended.
  69  */
  70 static int delay = 4;
  71 module_param(delay, int, 0);
  72 MODULE_PARM_DESC(delay, "Set adc sample delay.");
  73
  74 /*
  75  * Pen detect comparator threshold.
  76  *
  77  * 0 to Vmid in 15 steps, 0 = use zero power comparator with Vmid threshold
  78  * i.e. 1 =  Vmid/15 threshold
  79  *      15 =  Vmid/1 threshold
  80  *
  81  * Adjust this value if you are having problems with pen detect not
  82  * detecting any down events.
  83  */
  84 static int pdd = 8;
  85 module_param(pdd, int, 0);
  86 MODULE_PARM_DESC(pdd, "Set pen detect comparator threshold");
  87
  88 /*
  89  * Set adc mask function.
  90  *
  91  * Sources of glitch noise, such as signals driving an LCD display, may feed
  92  * through to the touch screen plates and affect measurement accuracy. In
  93  * order to minimise this, a signal may be applied to the MASK pin to delay or
  94  * synchronise the sampling.
  95  *
  96  * 0 = No delay or sync
  97  * 1 = High on pin stops conversions
  98  * 2 = Edge triggered, edge on pin delays conversion by delay param (above)
  99  * 3 = Edge triggered, edge on pin starts conversion after delay param
 100  */
 101 static int mask;
 102 module_param(mask, int, 0);
 103 MODULE_PARM_DESC(mask, "Set adc mask function.");
 104
 105 /*
 106  * ADC sample delay times in uS
 107  */
 108 static const int delay_table[] = {
 109         21,    /* 1 AC97 Link frames */
 110         42,    /* 2                  */
 111         84,    /* 4                  */
 112         167,   /* 8                  */
 113         333,   /* 16                 */
 114         667,   /* 32                 */
 115         1000,  /* 48                 */
 116         1333,  /* 64                 */
 117         2000,  /* 96                 */
 118         2667,  /* 128                */
 119         3333,  /* 160                */
 120         4000,  /* 192                */
 121         4667,  /* 224                */
 122         5333,  /* 256                */
 123         6000,  /* 288                */
 124         0      /* No delay, switch matrix always on */
 125 };
 126
 127 /*
 128  * Delay after issuing a POLL command.
 129  *
 130  * The delay is 3 AC97 link frames + the touchpanel settling delay
 131  */
 132 static inline void poll_delay(int d)
 133 {
 134         udelay(3 * AC97_LINK_FRAME + delay_table[d]);
 135 }
 136
 137 /*
 138  * set up the physical settings of the WM9705
 139  */
 140 static void wm9705_phy_init(struct wm97xx *wm)
 141 {
 142         u16 dig1 = 0, dig2 = WM97XX_RPR;
 143
 144         /*
 145         * mute VIDEO and AUX as they share X and Y touchscreen
 146         * inputs on the WM9705
 147         */
 148         wm97xx_reg_write(wm, AC97_AUX, 0x8000);
 149         wm97xx_reg_write(wm, AC97_VIDEO, 0x8000);
 150
 151         /* touchpanel pressure current*/
 152         if (pil == 2) {
 153                 dig2 |= WM9705_PIL;
 154                 dev_dbg(wm->dev,
 155                         "setting pressure measurement current to 400uA.");
 156         } else if (pil)
 157                 dev_dbg(wm->dev,
 158                         "setting pressure measurement current to 200uA.");
 159         if (!pil)
 160                 pressure = 0;
 161
 162         /* polling mode sample settling delay */
 163         if (delay != 4) {
 164                 if (delay < 0 || delay > 15) {
 165                         dev_dbg(wm->dev, "supplied delay out of range.");
 166                         delay = 4;
 167                 }
 168         }
 169         dig1 &= 0xff0f;
 170         dig1 |= WM97XX_DELAY(delay);
 171         dev_dbg(wm->dev, "setting adc sample delay to %d u Secs.",
 172                 delay_table[delay]);
 173
 174         /* WM9705 pdd */
 175         dig2 |= (pdd & 0x000f);
 176         dev_dbg(wm->dev, "setting pdd to Vmid/%d", 1 - (pdd & 0x000f));
 177
 178         /* mask */
 179         dig2 |= ((mask & 0x3) << 4);
 180
 181         wm97xx_reg_write(wm, AC97_WM97XX_DIGITISER1, dig1);
 182         wm97xx_reg_write(wm, AC97_WM97XX_DIGITISER2, dig2);
 183 }
 184
 185 static void wm9705_dig_enable(struct wm97xx *wm, int enable)
 186 {
 187         if (enable) {
 188                 wm97xx_reg_write(wm, AC97_WM97XX_DIGITISER2,
 189                                  wm->dig[2] | WM97XX_PRP_DET_DIG);
 190                 wm97xx_reg_read(wm, AC97_WM97XX_DIGITISER_RD); /* dummy read */
 191         } else
 192                 wm97xx_reg_write(wm, AC97_WM97XX_DIGITISER2,
 193                                  wm->dig[2] & ~WM97XX_PRP_DET_DIG);
 194 }
 195
 196 static void wm9705_aux_prepare(struct wm97xx *wm)
 197 {
 198         memcpy(wm->dig_save, wm->dig, sizeof(wm->dig));
 199         wm97xx_reg_write(wm, AC97_WM97XX_DIGITISER1, 0);
 200         wm97xx_reg_write(wm, AC97_WM97XX_DIGITISER2, WM97XX_PRP_DET_DIG);
 201 }
 202
 203 static void wm9705_dig_restore(struct wm97xx *wm)
 204 {
 205         wm97xx_reg_write(wm, AC97_WM97XX_DIGITISER1, wm->dig_save[1]);
 206         wm97xx_reg_write(wm, AC97_WM97XX_DIGITISER2, wm->dig_save[2]);
 207 }
 208
 209 static inline int is_pden(struct wm97xx *wm)
 210 {
 211         return wm->dig[2] & WM9705_PDEN;
 212 }
 213
 214 /*
 215  * Read a sample from the WM9705 adc in polling mode.
 216  */
 217 static int wm9705_poll_sample(struct wm97xx *wm, int adcsel, int *sample)
 218 {
 219         int timeout = 5 * delay;
 220
 221         if (!wm->pen_probably_down) {
 222                 u16 data = wm97xx_reg_read(wm, AC97_WM97XX_DIGITISER_RD);
 223                 if (!(data & WM97XX_PEN_DOWN))
 224                         return RC_PENUP;
 225                 wm->pen_probably_down = 1;
 226         }
 227
 228         /* set up digitiser */
 229         if (adcsel & 0x8000)
 230                 adcsel = ((adcsel & 0x7fff) + 3) << 12;
 231
 232         if (wm->mach_ops && wm->mach_ops->pre_sample)
 233                 wm->mach_ops->pre_sample(adcsel);
 234         wm97xx_reg_write(wm, AC97_WM97XX_DIGITISER1,
 235                          adcsel | WM97XX_POLL | WM97XX_DELAY(delay));
 236
 237         /* wait 3 AC97 time slots + delay for conversion */
 238         poll_delay(delay);
 239
 240         /* wait for POLL to go low */
 241         while ((wm97xx_reg_read(wm, AC97_WM97XX_DIGITISER1) & WM97XX_POLL)
 242                && timeout) {
 243                 udelay(AC97_LINK_FRAME);
 244                 timeout--;
 245         }
 246
 247         if (timeout == 0) {
 248                 /* If PDEN is set, we can get a timeout when pen goes up */
 249                 if (is_pden(wm))
 250                         wm->pen_probably_down = 0;
 251                 else
 252                         dev_dbg(wm->dev, "adc sample timeout");
 253                 return RC_PENUP;
 254         }
 255
 256         *sample = wm97xx_reg_read(wm, AC97_WM97XX_DIGITISER_RD);
 257         if (wm->mach_ops && wm->mach_ops->post_sample)
 258                 wm->mach_ops->post_sample(adcsel);
 259
 260         /* check we have correct sample */
 261         if ((*sample & WM97XX_ADCSEL_MASK) != adcsel) {
 262                 dev_dbg(wm->dev, "adc wrong sample, read %x got %x", adcsel,
 263                 *sample & WM97XX_ADCSEL_MASK);
 264                 return RC_PENUP;
 265         }
 266
 267         if (!(*sample & WM97XX_PEN_DOWN)) {
 268                 wm->pen_probably_down = 0;
 269                 return RC_PENUP;
 270         }
 271
 272         return RC_VALID;
 273 }
 274
 275 /*
 276  * Sample the WM9705 touchscreen in polling mode
 277  */
 278 static int wm9705_poll_touch(struct wm97xx *wm, struct wm97xx_data *data)
 279 {
 280         int rc;
 281
 282         rc = wm9705_poll_sample(wm, WM97XX_ADCSEL_X, &data->x);
 283         if (rc != RC_VALID)
 284                 return rc;
 285         rc = wm9705_poll_sample(wm, WM97XX_ADCSEL_Y, &data->y);
 286         if (rc != RC_VALID)
 287                 return rc;
 288         if (pil) {
 289                 rc = wm9705_poll_sample(wm, WM97XX_ADCSEL_PRES, &data->p);
 290                 if (rc != RC_VALID)
 291                         return rc;
 292         } else
 293                 data->p = DEFAULT_PRESSURE;
 294
 295         return RC_VALID;
 296 }
 297
 298 /*
 299  * Enable WM9705 continuous mode, i.e. touch data is streamed across
 300  * an AC97 slot
 301  */
 302 static int wm9705_acc_enable(struct wm97xx *wm, int enable)
 303 {
 304         u16 dig1, dig2;
 305         int ret = 0;
 306
 307         dig1 = wm->dig[1];
 308         dig2 = wm->dig[2];
 309
 310         if (enable) {
 311                 /* continous mode */
 312                 if (wm->mach_ops->acc_startup &&
 313                     (ret = wm->mach_ops->acc_startup(wm)) < 0)
 314                         return ret;
 315                 dig1 &= ~(WM97XX_CM_RATE_MASK | WM97XX_ADCSEL_MASK |
 316                           WM97XX_DELAY_MASK | WM97XX_SLT_MASK);
 317                 dig1 |= WM97XX_CTC | WM97XX_COO | WM97XX_SLEN |
 318                         WM97XX_DELAY(delay) |
 319                         WM97XX_SLT(wm->acc_slot) |
 320                         WM97XX_RATE(wm->acc_rate);
 321                 if (pil)
 322                         dig1 |= WM97XX_ADCSEL_PRES;
 323                 dig2 |= WM9705_PDEN;
 324         } else {
 325                 dig1 &= ~(WM97XX_CTC | WM97XX_COO | WM97XX_SLEN);
 326                 dig2 &= ~WM9705_PDEN;
 327                 if (wm->mach_ops->acc_shutdown)
 328                         wm->mach_ops->acc_shutdown(wm);
 329         }
 330
 331         wm97xx_reg_write(wm, AC97_WM97XX_DIGITISER1, dig1);
 332         wm97xx_reg_write(wm, AC97_WM97XX_DIGITISER2, dig2);
 333
 334         return ret;
 335 }
 336
 337 struct wm97xx_codec_drv wm9705_codec = {
 338         .id = WM9705_ID2,
 339         .name = "wm9705",
 340         .poll_sample = wm9705_poll_sample,
 341         .poll_touch = wm9705_poll_touch,
 342         .acc_enable = wm9705_acc_enable,
 343         .phy_init = wm9705_phy_init,
 344         .dig_enable = wm9705_dig_enable,
 345         .dig_restore = wm9705_dig_restore,
 346         .aux_prepare = wm9705_aux_prepare,
 347 };
 348 EXPORT_SYMBOL_GPL(wm9705_codec);
 349
 350 /* Module information */
 351 MODULE_AUTHOR("Liam Girdwood <liam.girdwood@wolfsonmicro.com>");
 352 MODULE_DESCRIPTION("WM9705 Touch Screen Driver");
 353 MODULE_LICENSE("GPL");