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  */
  38 static int pil;
  39 module_param(pil, int, 0);
  40 MODULE_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  */
  47 static int pressure = DEFAULT_PRESSURE & 0xfff;
  48 module_param(pressure, int, 0);
  49 MODULE_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  */
  63 static int delay = 4;
  64 module_param(delay, int, 0);
  65 MODULE_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  */
  77 static int pdd = 8;
  78 module_param(pdd, int, 0);
  79 MODULE_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  */
  94 static int mask;
  95 module_param(mask, int, 0);
  96 MODULE_PARM_DESC(mask, "Set adc mask function.");
  97
  98 /*
  99  * ADC sample delay times in uS
 100  */
 101 static 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  */
 125 static 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  */
 133 static 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
 178 static 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
 189 static 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
 196 static 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
 202 static 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  */
 210 static 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  */
 270 static 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  */
 294 static 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
 329 struct 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 };
 340 EXPORT_SYMBOL_GPL(wm9705_codec);
 341
 342 /* Module information */
 343 MODULE_AUTHOR("Liam Girdwood <lrg@slimlogic.co.uk>");
 344 MODULE_DESCRIPTION("WM9705 Touch Screen Driver");
 345 MODULE_LICENSE("GPL");