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