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