drivers/pwm/pwm-pca9685.c

   1 /*
   2  * Driver for PCA9685 16-channel 12-bit PWM LED controller
   3  *
   4  * Copyright (C) 2013 Steffen Trumtrar <s.trumtrar@pengutronix.de>
   5  * Copyright (C) 2015 Clemens Gruber <clemens.gruber@pqgruber.com>
   6  *
   7  * based on the pwm-twl-led.c driver
   8  *
   9  * This program is free software; you can redistribute it and/or modify it
  10  * under the terms of the GNU General Public License version 2 as published by
  11  * the Free Software Foundation.
  12  *
  13  * This program is distributed in the hope that it will be useful, but WITHOUT
  14  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  15  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  16  * more details.
  17  *
  18  * You should have received a copy of the GNU General Public License along with
  19  * this program.  If not, see <http://www.gnu.org/licenses/>.
  20  */
  21
  22 #include <linux/i2c.h>
  23 #include <linux/module.h>
  24 #include <linux/platform_device.h>
  25 #include <linux/pwm.h>
  26 #include <linux/regmap.h>
  27 #include <linux/slab.h>
  28 #include <linux/delay.h>
  29
  30 /*
  31  * Because the PCA9685 has only one prescaler per chip, changing the period of
  32  * one channel affects the period of all 16 PWM outputs!
  33  * However, the ratio between each configured duty cycle and the chip-wide
  34  * period remains constant, because the OFF time is set in proportion to the
  35  * counter range.
  36  */
  37
  38 #define PCA9685_MODE1           0x00
  39 #define PCA9685_MODE2           0x01
  40 #define PCA9685_SUBADDR1        0x02
  41 #define PCA9685_SUBADDR2        0x03
  42 #define PCA9685_SUBADDR3        0x04
  43 #define PCA9685_ALLCALLADDR     0x05
  44 #define PCA9685_LEDX_ON_L       0x06
  45 #define PCA9685_LEDX_ON_H       0x07
  46 #define PCA9685_LEDX_OFF_L      0x08
  47 #define PCA9685_LEDX_OFF_H      0x09
  48
  49 #define PCA9685_ALL_LED_ON_L    0xFA
  50 #define PCA9685_ALL_LED_ON_H    0xFB
  51 #define PCA9685_ALL_LED_OFF_L   0xFC
  52 #define PCA9685_ALL_LED_OFF_H   0xFD
  53 #define PCA9685_PRESCALE        0xFE
  54
  55 #define PCA9685_PRESCALE_MIN    0x03    /* => max. frequency of 1526 Hz */
  56 #define PCA9685_PRESCALE_MAX    0xFF    /* => min. frequency of 24 Hz */
  57
  58 #define PCA9685_COUNTER_RANGE   4096
  59 #define PCA9685_DEFAULT_PERIOD  5000000 /* Default period_ns = 1/200 Hz */
  60 #define PCA9685_OSC_CLOCK_MHZ   25      /* Internal oscillator with 25 MHz */
  61
  62 #define PCA9685_NUMREGS         0xFF
  63 #define PCA9685_MAXCHAN         0x10
  64
  65 #define LED_FULL                (1 << 4)
  66 #define MODE1_RESTART           (1 << 7)
  67 #define MODE1_SLEEP             (1 << 4)
  68 #define MODE2_INVRT             (1 << 4)
  69 #define MODE2_OUTDRV            (1 << 2)
  70
  71 #define LED_N_ON_H(N)   (PCA9685_LEDX_ON_H + (4 * (N)))
  72 #define LED_N_ON_L(N)   (PCA9685_LEDX_ON_L + (4 * (N)))
  73 #define LED_N_OFF_H(N)  (PCA9685_LEDX_OFF_H + (4 * (N)))
  74 #define LED_N_OFF_L(N)  (PCA9685_LEDX_OFF_L + (4 * (N)))
  75
  76 struct pca9685 {
  77         struct pwm_chip chip;
  78         struct regmap *regmap;
  79         int active_cnt;
  80         int duty_ns;
  81         int period_ns;
  82 };
  83
  84 static inline struct pca9685 *to_pca(struct pwm_chip *chip)
  85 {
  86         return container_of(chip, struct pca9685, chip);
  87 }
  88
  89 static int pca9685_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
  90                               int duty_ns, int period_ns)
  91 {
  92         struct pca9685 *pca = to_pca(chip);
  93         unsigned long long duty;
  94         unsigned int reg;
  95         int prescale;
  96
  97         if (period_ns != pca->period_ns) {
  98                 prescale = DIV_ROUND_CLOSEST(PCA9685_OSC_CLOCK_MHZ * period_ns,
  99                                              PCA9685_COUNTER_RANGE * 1000) - 1;
 100
 101                 if (prescale >= PCA9685_PRESCALE_MIN &&
 102                         prescale <= PCA9685_PRESCALE_MAX) {
 103                         /* Put chip into sleep mode */
 104                         regmap_update_bits(pca->regmap, PCA9685_MODE1,
 105                                            MODE1_SLEEP, MODE1_SLEEP);
 106
 107                         /* Change the chip-wide output frequency */
 108                         regmap_write(pca->regmap, PCA9685_PRESCALE, prescale);
 109
 110                         /* Wake the chip up */
 111                         regmap_update_bits(pca->regmap, PCA9685_MODE1,
 112                                            MODE1_SLEEP, 0x0);
 113
 114                         /* Wait 500us for the oscillator to be back up */
 115                         udelay(500);
 116
 117                         pca->period_ns = period_ns;
 118
 119                         /*
 120                          * If the duty cycle did not change, restart PWM with
 121                          * the same duty cycle to period ratio and return.
 122                          */
 123                         if (duty_ns == pca->duty_ns) {
 124                                 regmap_update_bits(pca->regmap, PCA9685_MODE1,
 125                                                    MODE1_RESTART, 0x1);
 126                                 return 0;
 127                         }
 128                 } else {
 129                         dev_err(chip->dev,
 130                                 "prescaler not set: period out of bounds!\n");
 131                         return -EINVAL;
 132                 }
 133         }
 134
 135         pca->duty_ns = duty_ns;
 136
 137         if (duty_ns < 1) {
 138                 if (pwm->hwpwm >= PCA9685_MAXCHAN)
 139                         reg = PCA9685_ALL_LED_OFF_H;
 140                 else
 141                         reg = LED_N_OFF_H(pwm->hwpwm);
 142
 143                 regmap_write(pca->regmap, reg, LED_FULL);
 144
 145                 return 0;
 146         }
 147
 148         if (duty_ns == period_ns) {
 149                 /* Clear both OFF registers */
 150                 if (pwm->hwpwm >= PCA9685_MAXCHAN)
 151                         reg = PCA9685_ALL_LED_OFF_L;
 152                 else
 153                         reg = LED_N_OFF_L(pwm->hwpwm);
 154
 155                 regmap_write(pca->regmap, reg, 0x0);
 156
 157                 if (pwm->hwpwm >= PCA9685_MAXCHAN)
 158                         reg = PCA9685_ALL_LED_OFF_H;
 159                 else
 160                         reg = LED_N_OFF_H(pwm->hwpwm);
 161
 162                 regmap_write(pca->regmap, reg, 0x0);
 163
 164                 /* Set the full ON bit */
 165                 if (pwm->hwpwm >= PCA9685_MAXCHAN)
 166                         reg = PCA9685_ALL_LED_ON_H;
 167                 else
 168                         reg = LED_N_ON_H(pwm->hwpwm);
 169
 170                 regmap_write(pca->regmap, reg, LED_FULL);
 171
 172                 return 0;
 173         }
 174
 175         duty = PCA9685_COUNTER_RANGE * (unsigned long long)duty_ns;
 176         duty = DIV_ROUND_UP_ULL(duty, period_ns);
 177
 178         if (pwm->hwpwm >= PCA9685_MAXCHAN)
 179                 reg = PCA9685_ALL_LED_OFF_L;
 180         else
 181                 reg = LED_N_OFF_L(pwm->hwpwm);
 182
 183         regmap_write(pca->regmap, reg, (int)duty & 0xff);
 184
 185         if (pwm->hwpwm >= PCA9685_MAXCHAN)
 186                 reg = PCA9685_ALL_LED_OFF_H;
 187         else
 188                 reg = LED_N_OFF_H(pwm->hwpwm);
 189
 190         regmap_write(pca->regmap, reg, ((int)duty >> 8) & 0xf);
 191
 192         /* Clear the full ON bit, otherwise the set OFF time has no effect */
 193         if (pwm->hwpwm >= PCA9685_MAXCHAN)
 194                 reg = PCA9685_ALL_LED_ON_H;
 195         else
 196                 reg = LED_N_ON_H(pwm->hwpwm);
 197
 198         regmap_write(pca->regmap, reg, 0);
 199
 200         return 0;
 201 }
 202
 203 static int pca9685_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
 204 {
 205         struct pca9685 *pca = to_pca(chip);
 206         unsigned int reg;
 207
 208         /*
 209          * The PWM subsystem does not support a pre-delay.
 210          * So, set the ON-timeout to 0
 211          */
 212         if (pwm->hwpwm >= PCA9685_MAXCHAN)
 213                 reg = PCA9685_ALL_LED_ON_L;
 214         else
 215                 reg = LED_N_ON_L(pwm->hwpwm);
 216
 217         regmap_write(pca->regmap, reg, 0);
 218
 219         if (pwm->hwpwm >= PCA9685_MAXCHAN)
 220                 reg = PCA9685_ALL_LED_ON_H;
 221         else
 222                 reg = LED_N_ON_H(pwm->hwpwm);
 223
 224         regmap_write(pca->regmap, reg, 0);
 225
 226         /*
 227          * Clear the full-off bit.
 228          * It has precedence over the others and must be off.
 229          */
 230         if (pwm->hwpwm >= PCA9685_MAXCHAN)
 231                 reg = PCA9685_ALL_LED_OFF_H;
 232         else
 233                 reg = LED_N_OFF_H(pwm->hwpwm);
 234
 235         regmap_update_bits(pca->regmap, reg, LED_FULL, 0x0);
 236
 237         return 0;
 238 }
 239
 240 static void pca9685_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 241 {
 242         struct pca9685 *pca = to_pca(chip);
 243         unsigned int reg;
 244
 245         if (pwm->hwpwm >= PCA9685_MAXCHAN)
 246                 reg = PCA9685_ALL_LED_OFF_H;
 247         else
 248                 reg = LED_N_OFF_H(pwm->hwpwm);
 249
 250         regmap_write(pca->regmap, reg, LED_FULL);
 251
 252         /* Clear the LED_OFF counter. */
 253         if (pwm->hwpwm >= PCA9685_MAXCHAN)
 254                 reg = PCA9685_ALL_LED_OFF_L;
 255         else
 256                 reg = LED_N_OFF_L(pwm->hwpwm);
 257
 258         regmap_write(pca->regmap, reg, 0x0);
 259 }
 260
 261 static int pca9685_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
 262 {
 263         struct pca9685 *pca = to_pca(chip);
 264
 265         if (pca->active_cnt++ == 0)
 266                 return regmap_update_bits(pca->regmap, PCA9685_MODE1,
 267                                           MODE1_SLEEP, 0x0);
 268
 269         return 0;
 270 }
 271
 272 static void pca9685_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
 273 {
 274         struct pca9685 *pca = to_pca(chip);
 275
 276         if (--pca->active_cnt == 0)
 277                 regmap_update_bits(pca->regmap, PCA9685_MODE1, MODE1_SLEEP,
 278                                    MODE1_SLEEP);
 279 }
 280
 281 static const struct pwm_ops pca9685_pwm_ops = {
 282         .enable = pca9685_pwm_enable,
 283         .disable = pca9685_pwm_disable,
 284         .config = pca9685_pwm_config,
 285         .request = pca9685_pwm_request,
 286         .free = pca9685_pwm_free,
 287         .owner = THIS_MODULE,
 288 };
 289
 290 static const struct regmap_config pca9685_regmap_i2c_config = {
 291         .reg_bits = 8,
 292         .val_bits = 8,
 293         .max_register = PCA9685_NUMREGS,
 294         .cache_type = REGCACHE_NONE,
 295 };
 296
 297 static int pca9685_pwm_probe(struct i2c_client *client,
 298                                 const struct i2c_device_id *id)
 299 {
 300         struct device_node *np = client->dev.of_node;
 301         struct pca9685 *pca;
 302         int ret;
 303         int mode2;
 304
 305         pca = devm_kzalloc(&client->dev, sizeof(*pca), GFP_KERNEL);
 306         if (!pca)
 307                 return -ENOMEM;
 308
 309         pca->regmap = devm_regmap_init_i2c(client, &pca9685_regmap_i2c_config);
 310         if (IS_ERR(pca->regmap)) {
 311                 ret = PTR_ERR(pca->regmap);
 312                 dev_err(&client->dev, "Failed to initialize register map: %d\n",
 313                         ret);
 314                 return ret;
 315         }
 316         pca->duty_ns = 0;
 317         pca->period_ns = PCA9685_DEFAULT_PERIOD;
 318
 319         i2c_set_clientdata(client, pca);
 320
 321         regmap_read(pca->regmap, PCA9685_MODE2, &mode2);
 322
 323         if (of_property_read_bool(np, "invert"))
 324                 mode2 |= MODE2_INVRT;
 325         else
 326                 mode2 &= ~MODE2_INVRT;
 327
 328         if (of_property_read_bool(np, "open-drain"))
 329                 mode2 &= ~MODE2_OUTDRV;
 330         else
 331                 mode2 |= MODE2_OUTDRV;
 332
 333         regmap_write(pca->regmap, PCA9685_MODE2, mode2);
 334
 335         /* clear all "full off" bits */
 336         regmap_write(pca->regmap, PCA9685_ALL_LED_OFF_L, 0);
 337         regmap_write(pca->regmap, PCA9685_ALL_LED_OFF_H, 0);
 338
 339         pca->chip.ops = &pca9685_pwm_ops;
 340         /* add an extra channel for ALL_LED */
 341         pca->chip.npwm = PCA9685_MAXCHAN + 1;
 342
 343         pca->chip.dev = &client->dev;
 344         pca->chip.base = -1;
 345         pca->chip.can_sleep = true;
 346
 347         return pwmchip_add(&pca->chip);
 348 }
 349
 350 static int pca9685_pwm_remove(struct i2c_client *client)
 351 {
 352         struct pca9685 *pca = i2c_get_clientdata(client);
 353
 354         regmap_update_bits(pca->regmap, PCA9685_MODE1, MODE1_SLEEP,
 355                            MODE1_SLEEP);
 356
 357         return pwmchip_remove(&pca->chip);
 358 }
 359
 360 static const struct i2c_device_id pca9685_id[] = {
 361         { "pca9685", 0 },
 362         { /* sentinel */ },
 363 };
 364 MODULE_DEVICE_TABLE(i2c, pca9685_id);
 365
 366 static const struct of_device_id pca9685_dt_ids[] = {
 367         { .compatible = "nxp,pca9685-pwm", },
 368         { /* sentinel */ }
 369 };
 370 MODULE_DEVICE_TABLE(of, pca9685_dt_ids);
 371
 372 static struct i2c_driver pca9685_i2c_driver = {
 373         .driver = {
 374                 .name = "pca9685-pwm",
 375                 .of_match_table = pca9685_dt_ids,
 376         },
 377         .probe = pca9685_pwm_probe,
 378         .remove = pca9685_pwm_remove,
 379         .id_table = pca9685_id,
 380 };
 381
 382 module_i2c_driver(pca9685_i2c_driver);
 383
 384 MODULE_AUTHOR("Steffen Trumtrar <s.trumtrar@pengutronix.de>");
 385 MODULE_DESCRIPTION("PWM driver for PCA9685");
 386 MODULE_LICENSE("GPL");