drivers/pwm/pwm-atmel-tcb.c

   1 /*
   2  * Copyright (C) Overkiz SAS 2012
   3  *
   4  * Author: Boris BREZILLON <b.brezillon@overkiz.com>
   5  * License terms: GNU General Public License (GPL) version 2
   6  */
   7
   8 #include <linux/module.h>
   9 #include <linux/init.h>
  10 #include <linux/clocksource.h>
  11 #include <linux/clockchips.h>
  12 #include <linux/interrupt.h>
  13 #include <linux/irq.h>
  14
  15 #include <linux/clk.h>
  16 #include <linux/err.h>
  17 #include <linux/ioport.h>
  18 #include <linux/io.h>
  19 #include <linux/platform_device.h>
  20 #include <linux/atmel_tc.h>
  21 #include <linux/pwm.h>
  22 #include <linux/of_device.h>
  23 #include <linux/slab.h>
  24
  25 #define NPWM    6
  26
  27 #define ATMEL_TC_ACMR_MASK      (ATMEL_TC_ACPA | ATMEL_TC_ACPC |        \
  28                                  ATMEL_TC_AEEVT | ATMEL_TC_ASWTRG)
  29
  30 #define ATMEL_TC_BCMR_MASK      (ATMEL_TC_BCPB | ATMEL_TC_BCPC |        \
  31                                  ATMEL_TC_BEEVT | ATMEL_TC_BSWTRG)
  32
  33 struct atmel_tcb_pwm_device {
  34         enum pwm_polarity polarity;     /* PWM polarity */
  35         unsigned div;                   /* PWM clock divider */
  36         unsigned duty;                  /* PWM duty expressed in clk cycles */
  37         unsigned period;                /* PWM period expressed in clk cycles */
  38 };
  39
  40 struct atmel_tcb_pwm_chip {
  41         struct pwm_chip chip;
  42         spinlock_t lock;
  43         struct atmel_tc *tc;
  44         struct atmel_tcb_pwm_device *pwms[NPWM];
  45 };
  46
  47 static inline struct atmel_tcb_pwm_chip *to_tcb_chip(struct pwm_chip *chip)
  48 {
  49         return container_of(chip, struct atmel_tcb_pwm_chip, chip);
  50 }
  51
  52 static int atmel_tcb_pwm_set_polarity(struct pwm_chip *chip,
  53                                       struct pwm_device *pwm,
  54                                       enum pwm_polarity polarity)
  55 {
  56         struct atmel_tcb_pwm_device *tcbpwm = pwm_get_chip_data(pwm);
  57
  58         tcbpwm->polarity = polarity;
  59
  60         return 0;
  61 }
  62
  63 static int atmel_tcb_pwm_request(struct pwm_chip *chip,
  64                                  struct pwm_device *pwm)
  65 {
  66         struct atmel_tcb_pwm_chip *tcbpwmc = to_tcb_chip(chip);
  67         struct atmel_tcb_pwm_device *tcbpwm;
  68         struct atmel_tc *tc = tcbpwmc->tc;
  69         void __iomem *regs = tc->regs;
  70         unsigned group = pwm->hwpwm / 2;
  71         unsigned index = pwm->hwpwm % 2;
  72         unsigned cmr;
  73         int ret;
  74
  75         tcbpwm = devm_kzalloc(chip->dev, sizeof(*tcbpwm), GFP_KERNEL);
  76         if (!tcbpwm)
  77                 return -ENOMEM;
  78
  79         ret = clk_prepare_enable(tc->clk[group]);
  80         if (ret) {
  81                 devm_kfree(chip->dev, tcbpwm);
  82                 return ret;
  83         }
  84
  85         pwm_set_chip_data(pwm, tcbpwm);
  86         tcbpwm->polarity = PWM_POLARITY_NORMAL;
  87         tcbpwm->duty = 0;
  88         tcbpwm->period = 0;
  89         tcbpwm->div = 0;
  90
  91         spin_lock(&tcbpwmc->lock);
  92         cmr = __raw_readl(regs + ATMEL_TC_REG(group, CMR));
  93         /*
  94          * Get init config from Timer Counter registers if
  95          * Timer Counter is already configured as a PWM generator.
  96          */
  97         if (cmr & ATMEL_TC_WAVE) {
  98                 if (index == 0)
  99                         tcbpwm->duty =
 100                                 __raw_readl(regs + ATMEL_TC_REG(group, RA));
 101                 else
 102                         tcbpwm->duty =
 103                                 __raw_readl(regs + ATMEL_TC_REG(group, RB));
 104
 105                 tcbpwm->div = cmr & ATMEL_TC_TCCLKS;
 106                 tcbpwm->period = __raw_readl(regs + ATMEL_TC_REG(group, RC));
 107                 cmr &= (ATMEL_TC_TCCLKS | ATMEL_TC_ACMR_MASK |
 108                         ATMEL_TC_BCMR_MASK);
 109         } else
 110                 cmr = 0;
 111
 112         cmr |= ATMEL_TC_WAVE | ATMEL_TC_WAVESEL_UP_AUTO | ATMEL_TC_EEVT_XC0;
 113         __raw_writel(cmr, regs + ATMEL_TC_REG(group, CMR));
 114         spin_unlock(&tcbpwmc->lock);
 115
 116         tcbpwmc->pwms[pwm->hwpwm] = tcbpwm;
 117
 118         return 0;
 119 }
 120
 121 static void atmel_tcb_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
 122 {
 123         struct atmel_tcb_pwm_chip *tcbpwmc = to_tcb_chip(chip);
 124         struct atmel_tcb_pwm_device *tcbpwm = pwm_get_chip_data(pwm);
 125         struct atmel_tc *tc = tcbpwmc->tc;
 126
 127         clk_disable_unprepare(tc->clk[pwm->hwpwm / 2]);
 128         tcbpwmc->pwms[pwm->hwpwm] = NULL;
 129         devm_kfree(chip->dev, tcbpwm);
 130 }
 131
 132 static void atmel_tcb_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 133 {
 134         struct atmel_tcb_pwm_chip *tcbpwmc = to_tcb_chip(chip);
 135         struct atmel_tcb_pwm_device *tcbpwm = pwm_get_chip_data(pwm);
 136         struct atmel_tc *tc = tcbpwmc->tc;
 137         void __iomem *regs = tc->regs;
 138         unsigned group = pwm->hwpwm / 2;
 139         unsigned index = pwm->hwpwm % 2;
 140         unsigned cmr;
 141         enum pwm_polarity polarity = tcbpwm->polarity;
 142
 143         /*
 144          * If duty is 0 the timer will be stopped and we have to
 145          * configure the output correctly on software trigger:
 146          *  - set output to high if PWM_POLARITY_INVERSED
 147          *  - set output to low if PWM_POLARITY_NORMAL
 148          *
 149          * This is why we're reverting polarity in this case.
 150          */
 151         if (tcbpwm->duty == 0)
 152                 polarity = !polarity;
 153
 154         spin_lock(&tcbpwmc->lock);
 155         cmr = __raw_readl(regs + ATMEL_TC_REG(group, CMR));
 156
 157         /* flush old setting and set the new one */
 158         if (index == 0) {
 159                 cmr &= ~ATMEL_TC_ACMR_MASK;
 160                 if (polarity == PWM_POLARITY_INVERSED)
 161                         cmr |= ATMEL_TC_ASWTRG_CLEAR;
 162                 else
 163                         cmr |= ATMEL_TC_ASWTRG_SET;
 164         } else {
 165                 cmr &= ~ATMEL_TC_BCMR_MASK;
 166                 if (polarity == PWM_POLARITY_INVERSED)
 167                         cmr |= ATMEL_TC_BSWTRG_CLEAR;
 168                 else
 169                         cmr |= ATMEL_TC_BSWTRG_SET;
 170         }
 171
 172         __raw_writel(cmr, regs + ATMEL_TC_REG(group, CMR));
 173
 174         /*
 175          * Use software trigger to apply the new setting.
 176          * If both PWM devices in this group are disabled we stop the clock.
 177          */
 178         if (!(cmr & (ATMEL_TC_ACPC | ATMEL_TC_BCPC)))
 179                 __raw_writel(ATMEL_TC_SWTRG | ATMEL_TC_CLKDIS,
 180                              regs + ATMEL_TC_REG(group, CCR));
 181         else
 182                 __raw_writel(ATMEL_TC_SWTRG, regs +
 183                              ATMEL_TC_REG(group, CCR));
 184
 185         spin_unlock(&tcbpwmc->lock);
 186 }
 187
 188 static int atmel_tcb_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
 189 {
 190         struct atmel_tcb_pwm_chip *tcbpwmc = to_tcb_chip(chip);
 191         struct atmel_tcb_pwm_device *tcbpwm = pwm_get_chip_data(pwm);
 192         struct atmel_tc *tc = tcbpwmc->tc;
 193         void __iomem *regs = tc->regs;
 194         unsigned group = pwm->hwpwm / 2;
 195         unsigned index = pwm->hwpwm % 2;
 196         u32 cmr;
 197         enum pwm_polarity polarity = tcbpwm->polarity;
 198
 199         /*
 200          * If duty is 0 the timer will be stopped and we have to
 201          * configure the output correctly on software trigger:
 202          *  - set output to high if PWM_POLARITY_INVERSED
 203          *  - set output to low if PWM_POLARITY_NORMAL
 204          *
 205          * This is why we're reverting polarity in this case.
 206          */
 207         if (tcbpwm->duty == 0)
 208                 polarity = !polarity;
 209
 210         spin_lock(&tcbpwmc->lock);
 211         cmr = __raw_readl(regs + ATMEL_TC_REG(group, CMR));
 212
 213         /* flush old setting and set the new one */
 214         cmr &= ~ATMEL_TC_TCCLKS;
 215
 216         if (index == 0) {
 217                 cmr &= ~ATMEL_TC_ACMR_MASK;
 218
 219                 /* Set CMR flags according to given polarity */
 220                 if (polarity == PWM_POLARITY_INVERSED)
 221                         cmr |= ATMEL_TC_ASWTRG_CLEAR;
 222                 else
 223                         cmr |= ATMEL_TC_ASWTRG_SET;
 224         } else {
 225                 cmr &= ~ATMEL_TC_BCMR_MASK;
 226                 if (polarity == PWM_POLARITY_INVERSED)
 227                         cmr |= ATMEL_TC_BSWTRG_CLEAR;
 228                 else
 229                         cmr |= ATMEL_TC_BSWTRG_SET;
 230         }
 231
 232         /*
 233          * If duty is 0 or equal to period there's no need to register
 234          * a specific action on RA/RB and RC compare.
 235          * The output will be configured on software trigger and keep
 236          * this config till next config call.
 237          */
 238         if (tcbpwm->duty != tcbpwm->period && tcbpwm->duty > 0) {
 239                 if (index == 0) {
 240                         if (polarity == PWM_POLARITY_INVERSED)
 241                                 cmr |= ATMEL_TC_ACPA_SET | ATMEL_TC_ACPC_CLEAR;
 242                         else
 243                                 cmr |= ATMEL_TC_ACPA_CLEAR | ATMEL_TC_ACPC_SET;
 244                 } else {
 245                         if (polarity == PWM_POLARITY_INVERSED)
 246                                 cmr |= ATMEL_TC_BCPB_SET | ATMEL_TC_BCPC_CLEAR;
 247                         else
 248                                 cmr |= ATMEL_TC_BCPB_CLEAR | ATMEL_TC_BCPC_SET;
 249                 }
 250         }
 251
 252         __raw_writel(cmr, regs + ATMEL_TC_REG(group, CMR));
 253
 254         if (index == 0)
 255                 __raw_writel(tcbpwm->duty, regs + ATMEL_TC_REG(group, RA));
 256         else
 257                 __raw_writel(tcbpwm->duty, regs + ATMEL_TC_REG(group, RB));
 258
 259         __raw_writel(tcbpwm->period, regs + ATMEL_TC_REG(group, RC));
 260
 261         /* Use software trigger to apply the new setting */
 262         __raw_writel(ATMEL_TC_CLKEN | ATMEL_TC_SWTRG,
 263                      regs + ATMEL_TC_REG(group, CCR));
 264         spin_unlock(&tcbpwmc->lock);
 265         return 0;
 266 }
 267
 268 static int atmel_tcb_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 269                                 int duty_ns, int period_ns)
 270 {
 271         struct atmel_tcb_pwm_chip *tcbpwmc = to_tcb_chip(chip);
 272         struct atmel_tcb_pwm_device *tcbpwm = pwm_get_chip_data(pwm);
 273         unsigned group = pwm->hwpwm / 2;
 274         unsigned index = pwm->hwpwm % 2;
 275         struct atmel_tcb_pwm_device *atcbpwm = NULL;
 276         struct atmel_tc *tc = tcbpwmc->tc;
 277         int i;
 278         int slowclk = 0;
 279         unsigned period;
 280         unsigned duty;
 281         unsigned rate = clk_get_rate(tc->clk[group]);
 282         unsigned long long min;
 283         unsigned long long max;
 284
 285         /*
 286          * Find best clk divisor:
 287          * the smallest divisor which can fulfill the period_ns requirements.
 288          */
 289         for (i = 0; i < 5; ++i) {
 290                 if (atmel_tc_divisors[i] == 0) {
 291                         slowclk = i;
 292                         continue;
 293                 }
 294                 min = div_u64((u64)NSEC_PER_SEC * atmel_tc_divisors[i], rate);
 295                 max = min << tc->tcb_config->counter_width;
 296                 if (max >= period_ns)
 297                         break;
 298         }
 299
 300         /*
 301          * If none of the divisor are small enough to represent period_ns
 302          * take slow clock (32KHz).
 303          */
 304         if (i == 5) {
 305                 i = slowclk;
 306                 rate = 32768;
 307                 min = div_u64(NSEC_PER_SEC, rate);
 308                 max = min << 16;
 309
 310                 /* If period is too big return ERANGE error */
 311                 if (max < period_ns)
 312                         return -ERANGE;
 313         }
 314
 315         duty = div_u64(duty_ns, min);
 316         period = div_u64(period_ns, min);
 317
 318         if (index == 0)
 319                 atcbpwm = tcbpwmc->pwms[pwm->hwpwm + 1];
 320         else
 321                 atcbpwm = tcbpwmc->pwms[pwm->hwpwm - 1];
 322
 323         /*
 324          * PWM devices provided by TCB driver are grouped by 2:
 325          * - group 0: PWM 0 & 1
 326          * - group 1: PWM 2 & 3
 327          * - group 2: PWM 4 & 5
 328          *
 329          * PWM devices in a given group must be configured with the
 330          * same period_ns.
 331          *
 332          * We're checking the period value of the second PWM device
 333          * in this group before applying the new config.
 334          */
 335         if ((atcbpwm && atcbpwm->duty > 0 &&
 336                         atcbpwm->duty != atcbpwm->period) &&
 337                 (atcbpwm->div != i || atcbpwm->period != period)) {
 338                 dev_err(chip->dev,
 339                         "failed to configure period_ns: PWM group already configured with a different value\n");
 340                 return -EINVAL;
 341         }
 342
 343         tcbpwm->period = period;
 344         tcbpwm->div = i;
 345         tcbpwm->duty = duty;
 346
 347         /* If the PWM is enabled, call enable to apply the new conf */
 348         if (test_bit(PWMF_ENABLED, &pwm->flags))
 349                 atmel_tcb_pwm_enable(chip, pwm);
 350
 351         return 0;
 352 }
 353
 354 static const struct pwm_ops atmel_tcb_pwm_ops = {
 355         .request = atmel_tcb_pwm_request,
 356         .free = atmel_tcb_pwm_free,
 357         .config = atmel_tcb_pwm_config,
 358         .set_polarity = atmel_tcb_pwm_set_polarity,
 359         .enable = atmel_tcb_pwm_enable,
 360         .disable = atmel_tcb_pwm_disable,
 361         .owner = THIS_MODULE,
 362 };
 363
 364 static int atmel_tcb_pwm_probe(struct platform_device *pdev)
 365 {
 366         struct atmel_tcb_pwm_chip *tcbpwm;
 367         struct device_node *np = pdev->dev.of_node;
 368         struct atmel_tc *tc;
 369         int err;
 370         int tcblock;
 371
 372         err = of_property_read_u32(np, "tc-block", &tcblock);
 373         if (err < 0) {
 374                 dev_err(&pdev->dev,
 375                         "failed to get Timer Counter Block number from device tree (error: %d)\n",
 376                         err);
 377                 return err;
 378         }
 379
 380         tc = atmel_tc_alloc(tcblock, "tcb-pwm");
 381         if (tc == NULL) {
 382                 dev_err(&pdev->dev, "failed to allocate Timer Counter Block\n");
 383                 return -ENOMEM;
 384         }
 385
 386         tcbpwm = devm_kzalloc(&pdev->dev, sizeof(*tcbpwm), GFP_KERNEL);
 387         if (tcbpwm == NULL) {
 388                 atmel_tc_free(tc);
 389                 dev_err(&pdev->dev, "failed to allocate memory\n");
 390                 return -ENOMEM;
 391         }
 392
 393         tcbpwm->chip.dev = &pdev->dev;
 394         tcbpwm->chip.ops = &atmel_tcb_pwm_ops;
 395         tcbpwm->chip.of_xlate = of_pwm_xlate_with_flags;
 396         tcbpwm->chip.of_pwm_n_cells = 3;
 397         tcbpwm->chip.base = -1;
 398         tcbpwm->chip.npwm = NPWM;
 399         tcbpwm->tc = tc;
 400
 401         spin_lock_init(&tcbpwm->lock);
 402
 403         err = pwmchip_add(&tcbpwm->chip);
 404         if (err < 0) {
 405                 atmel_tc_free(tc);
 406                 return err;
 407         }
 408
 409         platform_set_drvdata(pdev, tcbpwm);
 410
 411         return 0;
 412 }
 413
 414 static int atmel_tcb_pwm_remove(struct platform_device *pdev)
 415 {
 416         struct atmel_tcb_pwm_chip *tcbpwm = platform_get_drvdata(pdev);
 417         int err;
 418
 419         err = pwmchip_remove(&tcbpwm->chip);
 420         if (err < 0)
 421                 return err;
 422
 423         atmel_tc_free(tcbpwm->tc);
 424
 425         return 0;
 426 }
 427
 428 static const struct of_device_id atmel_tcb_pwm_dt_ids[] = {
 429         { .compatible = "atmel,tcb-pwm", },
 430         { /* sentinel */ }
 431 };
 432 MODULE_DEVICE_TABLE(of, atmel_tcb_pwm_dt_ids);
 433
 434 static struct platform_driver atmel_tcb_pwm_driver = {
 435         .driver = {
 436                 .name = "atmel-tcb-pwm",
 437                 .owner = THIS_MODULE,
 438                 .of_match_table = atmel_tcb_pwm_dt_ids,
 439         },
 440         .probe = atmel_tcb_pwm_probe,
 441         .remove = atmel_tcb_pwm_remove,
 442 };
 443 module_platform_driver(atmel_tcb_pwm_driver);
 444
 445 MODULE_AUTHOR("Boris BREZILLON <b.brezillon@overkiz.com>");
 446 MODULE_DESCRIPTION("Atmel Timer Counter Pulse Width Modulation Driver");
 447 MODULE_LICENSE("GPL v2");