linux/drivers/pwm/pwm-atmel-tcb.c
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   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
  33struct 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
  40struct 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
  47static 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
  52static 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
  63static 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_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
 121static 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(tc->clk[pwm->hwpwm / 2]);
 128        tcbpwmc->pwms[pwm->hwpwm] = NULL;
 129        devm_kfree(chip->dev, tcbpwm);
 130}
 131
 132static 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
 188static 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
 268static 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
 354static 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
 364static 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
 414static 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
 428static const struct of_device_id atmel_tcb_pwm_dt_ids[] = {
 429        { .compatible = "atmel,tcb-pwm", },
 430        { /* sentinel */ }
 431};
 432MODULE_DEVICE_TABLE(of, atmel_tcb_pwm_dt_ids);
 433
 434static struct platform_driver atmel_tcb_pwm_driver = {
 435        .driver = {
 436                .name = "atmel-tcb-pwm",
 437                .of_match_table = atmel_tcb_pwm_dt_ids,
 438        },
 439        .probe = atmel_tcb_pwm_probe,
 440        .remove = atmel_tcb_pwm_remove,
 441};
 442module_platform_driver(atmel_tcb_pwm_driver);
 443
 444MODULE_AUTHOR("Boris BREZILLON <b.brezillon@overkiz.com>");
 445MODULE_DESCRIPTION("Atmel Timer Counter Pulse Width Modulation Driver");
 446MODULE_LICENSE("GPL v2");
 447
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