drivers/pwm/pwm-stm32.c

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