LXR linux/drivers/input/touchscreen/wm9705.c

   1// SPDX-License-Identifier: GPL-2.0-or-later
   2/*
   3 * wm9705.c  --  Codec driver for Wolfson WM9705 AC97 Codec.
   4 *
   5 * Copyright 2003, 2004, 2005, 2006, 2007 Wolfson Microelectronics PLC.
   6 * Author: Liam Girdwood <lrg@slimlogic.co.uk>
   7 * Parts Copyright : Ian Molton <spyro@f2s.com>
   8 *                   Andrew Zabolotny <zap@homelink.ru>
   9 *                   Russell King <rmk@arm.linux.org.uk>
  10 */
  11
  12#include <linux/module.h>
  13#include <linux/moduleparam.h>
  14#include <linux/kernel.h>
  15#include <linux/input.h>
  16#include <linux/delay.h>
  17#include <linux/bitops.h>
  18#include <linux/wm97xx.h>
  19
  20#define TS_NAME                 "wm97xx"
  21#define WM9705_VERSION          "1.00"
  22#define DEFAULT_PRESSURE        0xb0c0
  23
  24/*
  25 * Module parameters
  26 */
  27
  28/*
  29 * Set current used for pressure measurement.
  30 *
  31 * Set pil = 2 to use 400uA
  32 *     pil = 1 to use 200uA and
  33 *     pil = 0 to disable pressure measurement.
  34 *
  35 * This is used to increase the range of values returned by the adc
  36 * when measureing touchpanel pressure.
  37 */
  38static int pil;
  39module_param(pil, int, 0);
  40MODULE_PARM_DESC(pil, "Set current used for pressure measurement.");
  41
  42/*
  43 * Set threshold for pressure measurement.
  44 *
  45 * Pen down pressure below threshold is ignored.
  46 */
  47static int pressure = DEFAULT_PRESSURE & 0xfff;
  48module_param(pressure, int, 0);
  49MODULE_PARM_DESC(pressure, "Set threshold for pressure measurement.");
  50
  51/*
  52 * Set adc sample delay.
  53 *
  54 * For accurate touchpanel measurements, some settling time may be
  55 * required between the switch matrix applying a voltage across the
  56 * touchpanel plate and the ADC sampling the signal.
  57 *
  58 * This delay can be set by setting delay = n, where n is the array
  59 * position of the delay in the array delay_table below.
  60 * Long delays > 1ms are supported for completeness, but are not
  61 * recommended.
  62 */
  63static int delay = 4;
  64module_param(delay, int, 0);
  65MODULE_PARM_DESC(delay, "Set adc sample delay.");
  66
  67/*
  68 * Pen detect comparator threshold.
  69 *
  70 * 0 to Vmid in 15 steps, 0 = use zero power comparator with Vmid threshold
  71 * i.e. 1 =  Vmid/15 threshold
  72 *      15 =  Vmid/1 threshold
  73 *
  74 * Adjust this value if you are having problems with pen detect not
  75 * detecting any down events.
  76 */
  77static int pdd = 8;
  78module_param(pdd, int, 0);
  79MODULE_PARM_DESC(pdd, "Set pen detect comparator threshold");
  80
  81/*
  82 * Set adc mask function.
  83 *
  84 * Sources of glitch noise, such as signals driving an LCD display, may feed
  85 * through to the touch screen plates and affect measurement accuracy. In
  86 * order to minimise this, a signal may be applied to the MASK pin to delay or
  87 * synchronise the sampling.
  88 *
  89 * 0 = No delay or sync
  90 * 1 = High on pin stops conversions
  91 * 2 = Edge triggered, edge on pin delays conversion by delay param (above)
  92 * 3 = Edge triggered, edge on pin starts conversion after delay param
  93 */
  94static int mask;
  95module_param(mask, int, 0);
  96MODULE_PARM_DESC(mask, "Set adc mask function.");
  97
  98/*
  99 * ADC sample delay times in uS
 100 */
 101static const int delay_table[] = {
 102        21,    /* 1 AC97 Link frames */
 103        42,    /* 2                  */
 104        84,    /* 4                  */
 105        167,   /* 8                  */
 106        333,   /* 16                 */
 107        667,   /* 32                 */
 108        1000,  /* 48                 */
 109        1333,  /* 64                 */
 110        2000,  /* 96                 */
 111        2667,  /* 128                */
 112        3333,  /* 160                */
 113        4000,  /* 192                */
 114        4667,  /* 224                */
 115        5333,  /* 256                */
 116        6000,  /* 288                */
 117        0      /* No delay, switch matrix always on */
 118};
 119
 120/*
 121 * Delay after issuing a POLL command.
 122 *
 123 * The delay is 3 AC97 link frames + the touchpanel settling delay
 124 */
 125static inline void poll_delay(int d)
 126{
 127        udelay(3 * AC97_LINK_FRAME + delay_table[d]);
 128}
 129
 130/*
 131 * set up the physical settings of the WM9705
 132 */
 133static void wm9705_phy_init(struct wm97xx *wm)
 134{
 135        u16 dig1 = 0, dig2 = WM97XX_RPR;
 136
 137        /*
 138        * mute VIDEO and AUX as they share X and Y touchscreen
 139        * inputs on the WM9705
 140        */
 141        wm97xx_reg_write(wm, AC97_AUX, 0x8000);
 142        wm97xx_reg_write(wm, AC97_VIDEO, 0x8000);
 143
 144        /* touchpanel pressure current*/
 145        if (pil == 2) {
 146                dig2 |= WM9705_PIL;
 147                dev_dbg(wm->dev,
 148                        "setting pressure measurement current to 400uA.");
 149        } else if (pil)
 150                dev_dbg(wm->dev,
 151                        "setting pressure measurement current to 200uA.");
 152        if (!pil)
 153                pressure = 0;
 154
 155        /* polling mode sample settling delay */
 156        if (delay != 4) {
 157                if (delay < 0 || delay > 15) {
 158                        dev_dbg(wm->dev, "supplied delay out of range.");
 159                        delay = 4;
 160                }
 161        }
 162        dig1 &= 0xff0f;
 163        dig1 |= WM97XX_DELAY(delay);
 164        dev_dbg(wm->dev, "setting adc sample delay to %d u Secs.",
 165                delay_table[delay]);
 166
 167        /* WM9705 pdd */
 168        dig2 |= (pdd & 0x000f);
 169        dev_dbg(wm->dev, "setting pdd to Vmid/%d", 1 - (pdd & 0x000f));
 170
 171        /* mask */
 172        dig2 |= ((mask & 0x3) << 4);
 173
 174        wm97xx_reg_write(wm, AC97_WM97XX_DIGITISER1, dig1);
 175        wm97xx_reg_write(wm, AC97_WM97XX_DIGITISER2, dig2);
 176}
 177
 178static void wm9705_dig_enable(struct wm97xx *wm, int enable)
 179{
 180        if (enable) {
 181                wm97xx_reg_write(wm, AC97_WM97XX_DIGITISER2,
 182                                 wm->dig[2] | WM97XX_PRP_DET_DIG);
 183                wm97xx_reg_read(wm, AC97_WM97XX_DIGITISER_RD); /* dummy read */
 184        } else
 185                wm97xx_reg_write(wm, AC97_WM97XX_DIGITISER2,
 186                                 wm->dig[2] & ~WM97XX_PRP_DET_DIG);
 187}
 188
 189static void wm9705_aux_prepare(struct wm97xx *wm)
 190{
 191        memcpy(wm->dig_save, wm->dig, sizeof(wm->dig));
 192        wm97xx_reg_write(wm, AC97_WM97XX_DIGITISER1, 0);
 193        wm97xx_reg_write(wm, AC97_WM97XX_DIGITISER2, WM97XX_PRP_DET_DIG);
 194}
 195
 196static void wm9705_dig_restore(struct wm97xx *wm)
 197{
 198        wm97xx_reg_write(wm, AC97_WM97XX_DIGITISER1, wm->dig_save[1]);
 199        wm97xx_reg_write(wm, AC97_WM97XX_DIGITISER2, wm->dig_save[2]);
 200}
 201
 202static inline int is_pden(struct wm97xx *wm)
 203{
 204        return wm->dig[2] & WM9705_PDEN;
 205}
 206
 207/*
 208 * Read a sample from the WM9705 adc in polling mode.
 209 */
 210static int wm9705_poll_sample(struct wm97xx *wm, int adcsel, int *sample)
 211{
 212        int timeout = 5 * delay;
 213        bool wants_pen = adcsel & WM97XX_PEN_DOWN;
 214
 215        if (wants_pen && !wm->pen_probably_down) {
 216                u16 data = wm97xx_reg_read(wm, AC97_WM97XX_DIGITISER_RD);
 217                if (!(data & WM97XX_PEN_DOWN))
 218                        return RC_PENUP;
 219                wm->pen_probably_down = 1;
 220        }
 221
 222        /* set up digitiser */
 223        if (wm->mach_ops && wm->mach_ops->pre_sample)
 224                wm->mach_ops->pre_sample(adcsel);
 225        wm97xx_reg_write(wm, AC97_WM97XX_DIGITISER1, (adcsel & WM97XX_ADCSEL_MASK)
 226                                | WM97XX_POLL | WM97XX_DELAY(delay));
 227
 228        /* wait 3 AC97 time slots + delay for conversion */
 229        poll_delay(delay);
 230
 231        /* wait for POLL to go low */
 232        while ((wm97xx_reg_read(wm, AC97_WM97XX_DIGITISER1) & WM97XX_POLL)
 233               && timeout) {
 234                udelay(AC97_LINK_FRAME);
 235                timeout--;
 236        }
 237
 238        if (timeout == 0) {
 239                /* If PDEN is set, we can get a timeout when pen goes up */
 240                if (is_pden(wm))
 241                        wm->pen_probably_down = 0;
 242                else
 243                        dev_dbg(wm->dev, "adc sample timeout");
 244                return RC_PENUP;
 245        }
 246
 247        *sample = wm97xx_reg_read(wm, AC97_WM97XX_DIGITISER_RD);
 248        if (wm->mach_ops && wm->mach_ops->post_sample)
 249                wm->mach_ops->post_sample(adcsel);
 250
 251        /* check we have correct sample */
 252        if ((*sample ^ adcsel) & WM97XX_ADCSEL_MASK) {
 253                dev_dbg(wm->dev, "adc wrong sample, wanted %x got %x",
 254                        adcsel & WM97XX_ADCSEL_MASK,
 255                        *sample & WM97XX_ADCSEL_MASK);
 256                return RC_PENUP;
 257        }
 258
 259        if (wants_pen && !(*sample & WM97XX_PEN_DOWN)) {
 260                wm->pen_probably_down = 0;
 261                return RC_PENUP;
 262        }
 263
 264        return RC_VALID;
 265}
 266
 267/*
 268 * Sample the WM9705 touchscreen in polling mode
 269 */
 270static int wm9705_poll_touch(struct wm97xx *wm, struct wm97xx_data *data)
 271{
 272        int rc;
 273
 274        rc = wm9705_poll_sample(wm, WM97XX_ADCSEL_X | WM97XX_PEN_DOWN, &data->x);
 275        if (rc != RC_VALID)
 276                return rc;
 277        rc = wm9705_poll_sample(wm, WM97XX_ADCSEL_Y | WM97XX_PEN_DOWN, &data->y);
 278        if (rc != RC_VALID)
 279                return rc;
 280        if (pil) {
 281                rc = wm9705_poll_sample(wm, WM97XX_ADCSEL_PRES | WM97XX_PEN_DOWN, &data->p);
 282                if (rc != RC_VALID)
 283                        return rc;
 284        } else
 285                data->p = DEFAULT_PRESSURE;
 286
 287        return RC_VALID;
 288}
 289
 290/*
 291 * Enable WM9705 continuous mode, i.e. touch data is streamed across
 292 * an AC97 slot
 293 */
 294static int wm9705_acc_enable(struct wm97xx *wm, int enable)
 295{
 296        u16 dig1, dig2;
 297        int ret = 0;
 298
 299        dig1 = wm->dig[1];
 300        dig2 = wm->dig[2];
 301
 302        if (enable) {
 303                /* continuous mode */
 304                if (wm->mach_ops->acc_startup &&
 305                    (ret = wm->mach_ops->acc_startup(wm)) < 0)
 306                        return ret;
 307                dig1 &= ~(WM97XX_CM_RATE_MASK | WM97XX_ADCSEL_MASK |
 308                          WM97XX_DELAY_MASK | WM97XX_SLT_MASK);
 309                dig1 |= WM97XX_CTC | WM97XX_COO | WM97XX_SLEN |
 310                        WM97XX_DELAY(delay) |
 311                        WM97XX_SLT(wm->acc_slot) |
 312                        WM97XX_RATE(wm->acc_rate);
 313                if (pil)
 314                        dig1 |= WM97XX_ADCSEL_PRES;
 315                dig2 |= WM9705_PDEN;
 316        } else {
 317                dig1 &= ~(WM97XX_CTC | WM97XX_COO | WM97XX_SLEN);
 318                dig2 &= ~WM9705_PDEN;
 319                if (wm->mach_ops->acc_shutdown)
 320                        wm->mach_ops->acc_shutdown(wm);
 321        }
 322
 323        wm97xx_reg_write(wm, AC97_WM97XX_DIGITISER1, dig1);
 324        wm97xx_reg_write(wm, AC97_WM97XX_DIGITISER2, dig2);
 325
 326        return ret;
 327}
 328
 329struct wm97xx_codec_drv wm9705_codec = {
 330        .id = WM9705_ID2,
 331        .name = "wm9705",
 332        .poll_sample = wm9705_poll_sample,
 333        .poll_touch = wm9705_poll_touch,
 334        .acc_enable = wm9705_acc_enable,
 335        .phy_init = wm9705_phy_init,
 336        .dig_enable = wm9705_dig_enable,
 337        .dig_restore = wm9705_dig_restore,
 338        .aux_prepare = wm9705_aux_prepare,
 339};
 340EXPORT_SYMBOL_GPL(wm9705_codec);
 341
 342/* Module information */
 343MODULE_AUTHOR("Liam Girdwood <lrg@slimlogic.co.uk>");
 344MODULE_DESCRIPTION("WM9705 Touch Screen Driver");
 345MODULE_LICENSE("GPL");
 346