drivers/pwm/pwm-stm32.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) STMicroelectronics 2016
   4  *
   5  * Author: Gerald Baeza <gerald.baeza@st.com>
   6  *
   7  * Inspired by timer-stm32.c from Maxime Coquelin
   8  *             pwm-atmel.c from Bo Shen
   9  */
  10
  11 #include <linux/mfd/stm32-timers.h>
  12 #include <linux/module.h>
  13 #include <linux/of.h>
  14 #include <linux/platform_device.h>
  15 #include <linux/pwm.h>
  16
  17 #define CCMR_CHANNEL_SHIFT 8
  18 #define CCMR_CHANNEL_MASK  0xFF
  19 #define MAX_BREAKINPUT 2
  20
  21 struct stm32_pwm {
  22         struct pwm_chip chip;
  23         struct mutex lock; /* protect pwm config/enable */
  24         struct clk *clk;
  25         struct regmap *regmap;
  26         u32 max_arr;
  27         bool have_complementary_output;
  28 };
  29
  30 struct stm32_breakinput {
  31         u32 index;
  32         u32 level;
  33         u32 filter;
  34 };
  35
  36 static inline struct stm32_pwm *to_stm32_pwm_dev(struct pwm_chip *chip)
  37 {
  38         return container_of(chip, struct stm32_pwm, chip);
  39 }
  40
  41 static u32 active_channels(struct stm32_pwm *dev)
  42 {
  43         u32 ccer;
  44
  45         regmap_read(dev->regmap, TIM_CCER, &ccer);
  46
  47         return ccer & TIM_CCER_CCXE;
  48 }
  49
  50 static int write_ccrx(struct stm32_pwm *dev, int ch, u32 value)
  51 {
  52         switch (ch) {
  53         case 0:
  54                 return regmap_write(dev->regmap, TIM_CCR1, value);
  55         case 1:
  56                 return regmap_write(dev->regmap, TIM_CCR2, value);
  57         case 2:
  58                 return regmap_write(dev->regmap, TIM_CCR3, value);
  59         case 3:
  60                 return regmap_write(dev->regmap, TIM_CCR4, value);
  61         }
  62         return -EINVAL;
  63 }
  64
  65 static int stm32_pwm_config(struct stm32_pwm *priv, int ch,
  66                             int duty_ns, int period_ns)
  67 {
  68         unsigned long long prd, div, dty;
  69         unsigned int prescaler = 0;
  70         u32 ccmr, mask, shift;
  71
  72         /* Period and prescaler values depends on clock rate */
  73         div = (unsigned long long)clk_get_rate(priv->clk) * period_ns;
  74
  75         do_div(div, NSEC_PER_SEC);
  76         prd = div;
  77
  78         while (div > priv->max_arr) {
  79                 prescaler++;
  80                 div = prd;
  81                 do_div(div, prescaler + 1);
  82         }
  83
  84         prd = div;
  85
  86         if (prescaler > MAX_TIM_PSC)
  87                 return -EINVAL;
  88
  89         /*
  90          * All channels share the same prescaler and counter so when two
  91          * channels are active at the same time we can't change them
  92          */
  93         if (active_channels(priv) & ~(1 << ch * 4)) {
  94                 u32 psc, arr;
  95
  96                 regmap_read(priv->regmap, TIM_PSC, &psc);
  97                 regmap_read(priv->regmap, TIM_ARR, &arr);
  98
  99                 if ((psc != prescaler) || (arr != prd - 1))
 100                         return -EBUSY;
 101         }
 102
 103         regmap_write(priv->regmap, TIM_PSC, prescaler);
 104         regmap_write(priv->regmap, TIM_ARR, prd - 1);
 105         regmap_update_bits(priv->regmap, TIM_CR1, TIM_CR1_ARPE, TIM_CR1_ARPE);
 106
 107         /* Calculate the duty cycles */
 108         dty = prd * duty_ns;
 109         do_div(dty, period_ns);
 110
 111         write_ccrx(priv, ch, dty);
 112
 113         /* Configure output mode */
 114         shift = (ch & 0x1) * CCMR_CHANNEL_SHIFT;
 115         ccmr = (TIM_CCMR_PE | TIM_CCMR_M1) << shift;
 116         mask = CCMR_CHANNEL_MASK << shift;
 117
 118         if (ch < 2)
 119                 regmap_update_bits(priv->regmap, TIM_CCMR1, mask, ccmr);
 120         else
 121                 regmap_update_bits(priv->regmap, TIM_CCMR2, mask, ccmr);
 122
 123         regmap_update_bits(priv->regmap, TIM_BDTR,
 124                            TIM_BDTR_MOE | TIM_BDTR_AOE,
 125                            TIM_BDTR_MOE | TIM_BDTR_AOE);
 126
 127         return 0;
 128 }
 129
 130 static int stm32_pwm_set_polarity(struct stm32_pwm *priv, int ch,
 131                                   enum pwm_polarity polarity)
 132 {
 133         u32 mask;
 134
 135         mask = TIM_CCER_CC1P << (ch * 4);
 136         if (priv->have_complementary_output)
 137                 mask |= TIM_CCER_CC1NP << (ch * 4);
 138
 139         regmap_update_bits(priv->regmap, TIM_CCER, mask,
 140                            polarity == PWM_POLARITY_NORMAL ? 0 : mask);
 141
 142         return 0;
 143 }
 144
 145 static int stm32_pwm_enable(struct stm32_pwm *priv, int ch)
 146 {
 147         u32 mask;
 148         int ret;
 149
 150         ret = clk_enable(priv->clk);
 151         if (ret)
 152                 return ret;
 153
 154         /* Enable channel */
 155         mask = TIM_CCER_CC1E << (ch * 4);
 156         if (priv->have_complementary_output)
 157                 mask |= TIM_CCER_CC1NE << (ch * 4);
 158
 159         regmap_update_bits(priv->regmap, TIM_CCER, mask, mask);
 160
 161         /* Make sure that registers are updated */
 162         regmap_update_bits(priv->regmap, TIM_EGR, TIM_EGR_UG, TIM_EGR_UG);
 163
 164         /* Enable controller */
 165         regmap_update_bits(priv->regmap, TIM_CR1, TIM_CR1_CEN, TIM_CR1_CEN);
 166
 167         return 0;
 168 }
 169
 170 static void stm32_pwm_disable(struct stm32_pwm *priv, int ch)
 171 {
 172         u32 mask;
 173
 174         /* Disable channel */
 175         mask = TIM_CCER_CC1E << (ch * 4);
 176         if (priv->have_complementary_output)
 177                 mask |= TIM_CCER_CC1NE << (ch * 4);
 178
 179         regmap_update_bits(priv->regmap, TIM_CCER, mask, 0);
 180
 181         /* When all channels are disabled, we can disable the controller */
 182         if (!active_channels(priv))
 183                 regmap_update_bits(priv->regmap, TIM_CR1, TIM_CR1_CEN, 0);
 184
 185         clk_disable(priv->clk);
 186 }
 187
 188 static int stm32_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 189                            struct pwm_state *state)
 190 {
 191         bool enabled;
 192         struct stm32_pwm *priv = to_stm32_pwm_dev(chip);
 193         int ret;
 194
 195         enabled = pwm->state.enabled;
 196
 197         if (enabled && !state->enabled) {
 198                 stm32_pwm_disable(priv, pwm->hwpwm);
 199                 return 0;
 200         }
 201
 202         if (state->polarity != pwm->state.polarity)
 203                 stm32_pwm_set_polarity(priv, pwm->hwpwm, state->polarity);
 204
 205         ret = stm32_pwm_config(priv, pwm->hwpwm,
 206                                state->duty_cycle, state->period);
 207         if (ret)
 208                 return ret;
 209
 210         if (!enabled && state->enabled)
 211                 ret = stm32_pwm_enable(priv, pwm->hwpwm);
 212
 213         return ret;
 214 }
 215
 216 static int stm32_pwm_apply_locked(struct pwm_chip *chip, struct pwm_device *pwm,
 217                                   struct pwm_state *state)
 218 {
 219         struct stm32_pwm *priv = to_stm32_pwm_dev(chip);
 220         int ret;
 221
 222         /* protect common prescaler for all active channels */
 223         mutex_lock(&priv->lock);
 224         ret = stm32_pwm_apply(chip, pwm, state);
 225         mutex_unlock(&priv->lock);
 226
 227         return ret;
 228 }
 229
 230 static const struct pwm_ops stm32pwm_ops = {
 231         .owner = THIS_MODULE,
 232         .apply = stm32_pwm_apply_locked,
 233 };
 234
 235 static int stm32_pwm_set_breakinput(struct stm32_pwm *priv,
 236                                     int index, int level, int filter)
 237 {
 238         u32 bke = (index == 0) ? TIM_BDTR_BKE : TIM_BDTR_BK2E;
 239         int shift = (index == 0) ? TIM_BDTR_BKF_SHIFT : TIM_BDTR_BK2F_SHIFT;
 240         u32 mask = (index == 0) ? TIM_BDTR_BKE | TIM_BDTR_BKP | TIM_BDTR_BKF
 241                                 : TIM_BDTR_BK2E | TIM_BDTR_BK2P | TIM_BDTR_BK2F;
 242         u32 bdtr = bke;
 243
 244         /*
 245          * The both bits could be set since only one will be wrote
 246          * due to mask value.
 247          */
 248         if (level)
 249                 bdtr |= TIM_BDTR_BKP | TIM_BDTR_BK2P;
 250
 251         bdtr |= (filter & TIM_BDTR_BKF_MASK) << shift;
 252
 253         regmap_update_bits(priv->regmap, TIM_BDTR, mask, bdtr);
 254
 255         regmap_read(priv->regmap, TIM_BDTR, &bdtr);
 256
 257         return (bdtr & bke) ? 0 : -EINVAL;
 258 }
 259
 260 static int stm32_pwm_apply_breakinputs(struct stm32_pwm *priv,
 261                                        struct device_node *np)
 262 {
 263         struct stm32_breakinput breakinput[MAX_BREAKINPUT];
 264         int nb, ret, i, array_size;
 265
 266         nb = of_property_count_elems_of_size(np, "st,breakinput",
 267                                              sizeof(struct stm32_breakinput));
 268
 269         /*
 270          * Because "st,breakinput" parameter is optional do not make probe
 271          * failed if it doesn't exist.
 272          */
 273         if (nb <= 0)
 274                 return 0;
 275
 276         if (nb > MAX_BREAKINPUT)
 277                 return -EINVAL;
 278
 279         array_size = nb * sizeof(struct stm32_breakinput) / sizeof(u32);
 280         ret = of_property_read_u32_array(np, "st,breakinput",
 281                                          (u32 *)breakinput, array_size);
 282         if (ret)
 283                 return ret;
 284
 285         for (i = 0; i < nb && !ret; i++) {
 286                 ret = stm32_pwm_set_breakinput(priv,
 287                                                breakinput[i].index,
 288                                                breakinput[i].level,
 289                                                breakinput[i].filter);
 290         }
 291
 292         return ret;
 293 }
 294
 295 static void stm32_pwm_detect_complementary(struct stm32_pwm *priv)
 296 {
 297         u32 ccer;
 298
 299         /*
 300          * If complementary bit doesn't exist writing 1 will have no
 301          * effect so we can detect it.
 302          */
 303         regmap_update_bits(priv->regmap,
 304                            TIM_CCER, TIM_CCER_CC1NE, TIM_CCER_CC1NE);
 305         regmap_read(priv->regmap, TIM_CCER, &ccer);
 306         regmap_update_bits(priv->regmap, TIM_CCER, TIM_CCER_CC1NE, 0);
 307
 308         priv->have_complementary_output = (ccer != 0);
 309 }
 310
 311 static int stm32_pwm_detect_channels(struct stm32_pwm *priv)
 312 {
 313         u32 ccer;
 314         int npwm = 0;
 315
 316         /*
 317          * If channels enable bits don't exist writing 1 will have no
 318          * effect so we can detect and count them.
 319          */
 320         regmap_update_bits(priv->regmap,
 321                            TIM_CCER, TIM_CCER_CCXE, TIM_CCER_CCXE);
 322         regmap_read(priv->regmap, TIM_CCER, &ccer);
 323         regmap_update_bits(priv->regmap, TIM_CCER, TIM_CCER_CCXE, 0);
 324
 325         if (ccer & TIM_CCER_CC1E)
 326                 npwm++;
 327
 328         if (ccer & TIM_CCER_CC2E)
 329                 npwm++;
 330
 331         if (ccer & TIM_CCER_CC3E)
 332                 npwm++;
 333
 334         if (ccer & TIM_CCER_CC4E)
 335                 npwm++;
 336
 337         return npwm;
 338 }
 339
 340 static int stm32_pwm_probe(struct platform_device *pdev)
 341 {
 342         struct device *dev = &pdev->dev;
 343         struct device_node *np = dev->of_node;
 344         struct stm32_timers *ddata = dev_get_drvdata(pdev->dev.parent);
 345         struct stm32_pwm *priv;
 346         int ret;
 347
 348         priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
 349         if (!priv)
 350                 return -ENOMEM;
 351
 352         mutex_init(&priv->lock);
 353         priv->regmap = ddata->regmap;
 354         priv->clk = ddata->clk;
 355         priv->max_arr = ddata->max_arr;
 356
 357         if (!priv->regmap || !priv->clk)
 358                 return -EINVAL;
 359
 360         ret = stm32_pwm_apply_breakinputs(priv, np);
 361         if (ret)
 362                 return ret;
 363
 364         stm32_pwm_detect_complementary(priv);
 365
 366         priv->chip.base = -1;
 367         priv->chip.dev = dev;
 368         priv->chip.ops = &stm32pwm_ops;
 369         priv->chip.npwm = stm32_pwm_detect_channels(priv);
 370
 371         ret = pwmchip_add(&priv->chip);
 372         if (ret < 0)
 373                 return ret;
 374
 375         platform_set_drvdata(pdev, priv);
 376
 377         return 0;
 378 }
 379
 380 static int stm32_pwm_remove(struct platform_device *pdev)
 381 {
 382         struct stm32_pwm *priv = platform_get_drvdata(pdev);
 383         unsigned int i;
 384
 385         for (i = 0; i < priv->chip.npwm; i++)
 386                 pwm_disable(&priv->chip.pwms[i]);
 387
 388         pwmchip_remove(&priv->chip);
 389
 390         return 0;
 391 }
 392
 393 static const struct of_device_id stm32_pwm_of_match[] = {
 394         { .compatible = "st,stm32-pwm", },
 395         { /* end node */ },
 396 };
 397 MODULE_DEVICE_TABLE(of, stm32_pwm_of_match);
 398
 399 static struct platform_driver stm32_pwm_driver = {
 400         .probe  = stm32_pwm_probe,
 401         .remove = stm32_pwm_remove,
 402         .driver = {
 403                 .name = "stm32-pwm",
 404                 .of_match_table = stm32_pwm_of_match,
 405         },
 406 };
 407 module_platform_driver(stm32_pwm_driver);
 408
 409 MODULE_ALIAS("platform:stm32-pwm");
 410 MODULE_DESCRIPTION("STMicroelectronics STM32 PWM driver");
 411 MODULE_LICENSE("GPL v2");