drivers/pwm/pwm-stmpe.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2016 Linaro Ltd.
   4  *
   5  * Author: Linus Walleij <linus.walleij@linaro.org>
   6  */
   7
   8 #include <linux/bitops.h>
   9 #include <linux/delay.h>
  10 #include <linux/err.h>
  11 #include <linux/mfd/stmpe.h>
  12 #include <linux/module.h>
  13 #include <linux/of.h>
  14 #include <linux/platform_device.h>
  15 #include <linux/pwm.h>
  16 #include <linux/slab.h>
  17
  18 #define STMPE24XX_PWMCS         0x30
  19 #define PWMCS_EN_PWM0           BIT(0)
  20 #define PWMCS_EN_PWM1           BIT(1)
  21 #define PWMCS_EN_PWM2           BIT(2)
  22 #define STMPE24XX_PWMIC0        0x38
  23 #define STMPE24XX_PWMIC1        0x39
  24 #define STMPE24XX_PWMIC2        0x3a
  25
  26 #define STMPE_PWM_24XX_PINBASE  21
  27
  28 struct stmpe_pwm {
  29         struct stmpe *stmpe;
  30         struct pwm_chip chip;
  31         u8 last_duty;
  32 };
  33
  34 static inline struct stmpe_pwm *to_stmpe_pwm(struct pwm_chip *chip)
  35 {
  36         return container_of(chip, struct stmpe_pwm, chip);
  37 }
  38
  39 static int stmpe_24xx_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
  40 {
  41         struct stmpe_pwm *stmpe_pwm = to_stmpe_pwm(chip);
  42         u8 value;
  43         int ret;
  44
  45         ret = stmpe_reg_read(stmpe_pwm->stmpe, STMPE24XX_PWMCS);
  46         if (ret < 0) {
  47                 dev_err(chip->dev, "error reading PWM#%u control\n",
  48                         pwm->hwpwm);
  49                 return ret;
  50         }
  51
  52         value = ret | BIT(pwm->hwpwm);
  53
  54         ret = stmpe_reg_write(stmpe_pwm->stmpe, STMPE24XX_PWMCS, value);
  55         if (ret) {
  56                 dev_err(chip->dev, "error writing PWM#%u control\n",
  57                         pwm->hwpwm);
  58                 return ret;
  59         }
  60
  61         return 0;
  62 }
  63
  64 static int stmpe_24xx_pwm_disable(struct pwm_chip *chip,
  65                                   struct pwm_device *pwm)
  66 {
  67         struct stmpe_pwm *stmpe_pwm = to_stmpe_pwm(chip);
  68         u8 value;
  69         int ret;
  70
  71         ret = stmpe_reg_read(stmpe_pwm->stmpe, STMPE24XX_PWMCS);
  72         if (ret < 0) {
  73                 dev_err(chip->dev, "error reading PWM#%u control\n",
  74                         pwm->hwpwm);
  75                 return ret;
  76         }
  77
  78         value = ret & ~BIT(pwm->hwpwm);
  79
  80         ret = stmpe_reg_write(stmpe_pwm->stmpe, STMPE24XX_PWMCS, value);
  81         if (ret)
  82                 dev_err(chip->dev, "error writing PWM#%u control\n",
  83                         pwm->hwpwm);
  84         return ret;
  85 }
  86
  87 /* STMPE 24xx PWM instructions */
  88 #define SMAX            0x007f
  89 #define SMIN            0x00ff
  90 #define GTS             0x0000
  91 #define LOAD            BIT(14) /* Only available on 2403 */
  92 #define RAMPUP          0x0000
  93 #define RAMPDOWN        BIT(7)
  94 #define PRESCALE_512    BIT(14)
  95 #define STEPTIME_1      BIT(8)
  96 #define BRANCH          (BIT(15) | BIT(13))
  97
  98 static int stmpe_24xx_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
  99                                  int duty_ns, int period_ns)
 100 {
 101         struct stmpe_pwm *stmpe_pwm = to_stmpe_pwm(chip);
 102         unsigned int i, pin;
 103         u16 program[3] = {
 104                 SMAX,
 105                 GTS,
 106                 GTS,
 107         };
 108         u8 offset;
 109         int ret;
 110
 111         /* Make sure we are disabled */
 112         if (pwm_is_enabled(pwm)) {
 113                 ret = stmpe_24xx_pwm_disable(chip, pwm);
 114                 if (ret)
 115                         return ret;
 116         } else {
 117                 /* Connect the PWM to the pin */
 118                 pin = pwm->hwpwm;
 119
 120                 /* On STMPE2401 and 2403 pins 21,22,23 are used */
 121                 if (stmpe_pwm->stmpe->partnum == STMPE2401 ||
 122                     stmpe_pwm->stmpe->partnum == STMPE2403)
 123                         pin += STMPE_PWM_24XX_PINBASE;
 124
 125                 ret = stmpe_set_altfunc(stmpe_pwm->stmpe, BIT(pin),
 126                                         STMPE_BLOCK_PWM);
 127                 if (ret) {
 128                         dev_err(chip->dev, "unable to connect PWM#%u to pin\n",
 129                                 pwm->hwpwm);
 130                         return ret;
 131                 }
 132         }
 133
 134         /* STMPE24XX */
 135         switch (pwm->hwpwm) {
 136         case 0:
 137                 offset = STMPE24XX_PWMIC0;
 138                 break;
 139
 140         case 1:
 141                 offset = STMPE24XX_PWMIC1;
 142                 break;
 143
 144         case 2:
 145                 offset = STMPE24XX_PWMIC2;
 146                 break;
 147
 148         default:
 149                 /* Should not happen as npwm is 3 */
 150                 return -ENODEV;
 151         }
 152
 153         dev_dbg(chip->dev, "PWM#%u: config duty %d ns, period %d ns\n",
 154                 pwm->hwpwm, duty_ns, period_ns);
 155
 156         if (duty_ns == 0) {
 157                 if (stmpe_pwm->stmpe->partnum == STMPE2401)
 158                         program[0] = SMAX; /* off all the time */
 159
 160                 if (stmpe_pwm->stmpe->partnum == STMPE2403)
 161                         program[0] = LOAD | 0xff; /* LOAD 0xff */
 162
 163                 stmpe_pwm->last_duty = 0x00;
 164         } else if (duty_ns == period_ns) {
 165                 if (stmpe_pwm->stmpe->partnum == STMPE2401)
 166                         program[0] = SMIN; /* on all the time */
 167
 168                 if (stmpe_pwm->stmpe->partnum == STMPE2403)
 169                         program[0] = LOAD | 0x00; /* LOAD 0x00 */
 170
 171                 stmpe_pwm->last_duty = 0xff;
 172         } else {
 173                 u8 value, last = stmpe_pwm->last_duty;
 174                 unsigned long duty;
 175
 176                 /*
 177                  * Counter goes from 0x00 to 0xff repeatedly at 32768 Hz,
 178                  * (means a period of 30517 ns) then this is compared to the
 179                  * counter from the ramp, if this is >= PWM counter the output
 180                  * is high. With LOAD we can define how much of the cycle it
 181                  * is on.
 182                  *
 183                  * Prescale = 0 -> 2 kHz -> T = 1/f = 488281.25 ns
 184                  */
 185
 186                 /* Scale to 0..0xff */
 187                 duty = duty_ns * 256;
 188                 duty = DIV_ROUND_CLOSEST(duty, period_ns);
 189                 value = duty;
 190
 191                 if (value == last) {
 192                         /* Run the old program */
 193                         if (pwm_is_enabled(pwm))
 194                                 stmpe_24xx_pwm_enable(chip, pwm);
 195
 196                         return 0;
 197                 } else if (stmpe_pwm->stmpe->partnum == STMPE2403) {
 198                         /* STMPE2403 can simply set the right PWM value */
 199                         program[0] = LOAD | value;
 200                         program[1] = 0x0000;
 201                 } else if (stmpe_pwm->stmpe->partnum == STMPE2401) {
 202                         /* STMPE2401 need a complex program */
 203                         u16 incdec = 0x0000;
 204
 205                         if (last < value)
 206                                 /* Count up */
 207                                 incdec = RAMPUP | (value - last);
 208                         else
 209                                 /* Count down */
 210                                 incdec = RAMPDOWN | (last - value);
 211
 212                         /* Step to desired value, smoothly */
 213                         program[0] = PRESCALE_512 | STEPTIME_1 | incdec;
 214
 215                         /* Loop eternally to 0x00 */
 216                         program[1] = BRANCH;
 217                 }
 218
 219                 dev_dbg(chip->dev,
 220                         "PWM#%u: value = %02x, last_duty = %02x, program=%04x,%04x,%04x\n",
 221                         pwm->hwpwm, value, last, program[0], program[1],
 222                         program[2]);
 223                 stmpe_pwm->last_duty = value;
 224         }
 225
 226         /*
 227          * We can write programs of up to 64 16-bit words into this channel.
 228          */
 229         for (i = 0; i < ARRAY_SIZE(program); i++) {
 230                 u8 value;
 231
 232                 value = (program[i] >> 8) & 0xff;
 233
 234                 ret = stmpe_reg_write(stmpe_pwm->stmpe, offset, value);
 235                 if (ret) {
 236                         dev_err(chip->dev, "error writing register %02x: %d\n",
 237                                 offset, ret);
 238                         return ret;
 239                 }
 240
 241                 value = program[i] & 0xff;
 242
 243                 ret = stmpe_reg_write(stmpe_pwm->stmpe, offset, value);
 244                 if (ret) {
 245                         dev_err(chip->dev, "error writing register %02x: %d\n",
 246                                 offset, ret);
 247                         return ret;
 248                 }
 249         }
 250
 251         /* If we were enabled, re-enable this PWM */
 252         if (pwm_is_enabled(pwm))
 253                 stmpe_24xx_pwm_enable(chip, pwm);
 254
 255         /* Sleep for 200ms so we're sure it will take effect */
 256         msleep(200);
 257
 258         dev_dbg(chip->dev, "programmed PWM#%u, %u bytes\n", pwm->hwpwm, i);
 259
 260         return 0;
 261 }
 262
 263 static int stmpe_24xx_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 264                                 const struct pwm_state *state)
 265 {
 266         int err;
 267
 268         if (state->polarity != PWM_POLARITY_NORMAL)
 269                 return -EINVAL;
 270
 271         if (!state->enabled) {
 272                 if (pwm->state.enabled)
 273                         return stmpe_24xx_pwm_disable(chip, pwm);
 274
 275                 return 0;
 276         }
 277
 278         err = stmpe_24xx_pwm_config(pwm->chip, pwm, state->duty_cycle, state->period);
 279         if (err)
 280                 return err;
 281
 282         if (!pwm->state.enabled)
 283                 err = stmpe_24xx_pwm_enable(chip, pwm);
 284
 285         return err;
 286 }
 287
 288 static const struct pwm_ops stmpe_24xx_pwm_ops = {
 289         .apply = stmpe_24xx_pwm_apply,
 290         .owner = THIS_MODULE,
 291 };
 292
 293 static int __init stmpe_pwm_probe(struct platform_device *pdev)
 294 {
 295         struct stmpe *stmpe = dev_get_drvdata(pdev->dev.parent);
 296         struct stmpe_pwm *stmpe_pwm;
 297         int ret;
 298
 299         stmpe_pwm = devm_kzalloc(&pdev->dev, sizeof(*stmpe_pwm), GFP_KERNEL);
 300         if (!stmpe_pwm)
 301                 return -ENOMEM;
 302
 303         stmpe_pwm->stmpe = stmpe;
 304         stmpe_pwm->chip.dev = &pdev->dev;
 305
 306         if (stmpe->partnum == STMPE2401 || stmpe->partnum == STMPE2403) {
 307                 stmpe_pwm->chip.ops = &stmpe_24xx_pwm_ops;
 308                 stmpe_pwm->chip.npwm = 3;
 309         } else {
 310                 if (stmpe->partnum == STMPE1601)
 311                         dev_err(&pdev->dev, "STMPE1601 not yet supported\n");
 312                 else
 313                         dev_err(&pdev->dev, "Unknown STMPE PWM\n");
 314
 315                 return -ENODEV;
 316         }
 317
 318         ret = stmpe_enable(stmpe, STMPE_BLOCK_PWM);
 319         if (ret)
 320                 return ret;
 321
 322         ret = pwmchip_add(&stmpe_pwm->chip);
 323         if (ret) {
 324                 stmpe_disable(stmpe, STMPE_BLOCK_PWM);
 325                 return ret;
 326         }
 327
 328         return 0;
 329 }
 330
 331 static struct platform_driver stmpe_pwm_driver = {
 332         .driver = {
 333                 .name = "stmpe-pwm",
 334         },
 335 };
 336 builtin_platform_driver_probe(stmpe_pwm_driver, stmpe_pwm_probe);