LXR linux/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
  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_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
 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_unprepare(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        cmr |= (tcbpwm->div & ATMEL_TC_TCCLKS);
 253
 254        __raw_writel(cmr, regs + ATMEL_TC_REG(group, CMR));
 255
 256        if (index == 0)
 257                __raw_writel(tcbpwm->duty, regs + ATMEL_TC_REG(group, RA));
 258        else
 259                __raw_writel(tcbpwm->duty, regs + ATMEL_TC_REG(group, RB));
 260
 261        __raw_writel(tcbpwm->period, regs + ATMEL_TC_REG(group, RC));
 262
 263        /* Use software trigger to apply the new setting */
 264        __raw_writel(ATMEL_TC_CLKEN | ATMEL_TC_SWTRG,
 265                     regs + ATMEL_TC_REG(group, CCR));
 266        spin_unlock(&tcbpwmc->lock);
 267        return 0;
 268}
 269
 270static int atmel_tcb_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 271                                int duty_ns, int period_ns)
 272{
 273        struct atmel_tcb_pwm_chip *tcbpwmc = to_tcb_chip(chip);
 274        struct atmel_tcb_pwm_device *tcbpwm = pwm_get_chip_data(pwm);
 275        unsigned group = pwm->hwpwm / 2;
 276        unsigned index = pwm->hwpwm % 2;
 277        struct atmel_tcb_pwm_device *atcbpwm = NULL;
 278        struct atmel_tc *tc = tcbpwmc->tc;
 279        int i;
 280        int slowclk = 0;
 281        unsigned period;
 282        unsigned duty;
 283        unsigned rate = clk_get_rate(tc->clk[group]);
 284        unsigned long long min;
 285        unsigned long long max;
 286
 287        /*
 288         * Find best clk divisor:
 289         * the smallest divisor which can fulfill the period_ns requirements.
 290         */
 291        for (i = 0; i < 5; ++i) {
 292                if (atmel_tc_divisors[i] == 0) {
 293                        slowclk = i;
 294                        continue;
 295                }
 296                min = div_u64((u64)NSEC_PER_SEC * atmel_tc_divisors[i], rate);
 297                max = min << tc->tcb_config->counter_width;
 298                if (max >= period_ns)
 299                        break;
 300        }
 301
 302        /*
 303         * If none of the divisor are small enough to represent period_ns
 304         * take slow clock (32KHz).
 305         */
 306        if (i == 5) {
 307                i = slowclk;
 308                rate = 32768;
 309                min = div_u64(NSEC_PER_SEC, rate);
 310                max = min << tc->tcb_config->counter_width;
 311
 312                /* If period is too big return ERANGE error */
 313                if (max < period_ns)
 314                        return -ERANGE;
 315        }
 316
 317        duty = div_u64(duty_ns, min);
 318        period = div_u64(period_ns, min);
 319
 320        if (index == 0)
 321                atcbpwm = tcbpwmc->pwms[pwm->hwpwm + 1];
 322        else
 323                atcbpwm = tcbpwmc->pwms[pwm->hwpwm - 1];
 324
 325        /*
 326         * PWM devices provided by TCB driver are grouped by 2:
 327         * - group 0: PWM 0 & 1
 328         * - group 1: PWM 2 & 3
 329         * - group 2: PWM 4 & 5
 330         *
 331         * PWM devices in a given group must be configured with the
 332         * same period_ns.
 333         *
 334         * We're checking the period value of the second PWM device
 335         * in this group before applying the new config.
 336         */
 337        if ((atcbpwm && atcbpwm->duty > 0 &&
 338                        atcbpwm->duty != atcbpwm->period) &&
 339                (atcbpwm->div != i || atcbpwm->period != period)) {
 340                dev_err(chip->dev,
 341                        "failed to configure period_ns: PWM group already configured with a different value\n");
 342                return -EINVAL;
 343        }
 344
 345        tcbpwm->period = period;
 346        tcbpwm->div = i;
 347        tcbpwm->duty = duty;
 348
 349        /* If the PWM is enabled, call enable to apply the new conf */
 350        if (test_bit(PWMF_ENABLED, &pwm->flags))
 351                atmel_tcb_pwm_enable(chip, pwm);
 352
 353        return 0;
 354}
 355
 356static const struct pwm_ops atmel_tcb_pwm_ops = {
 357        .request = atmel_tcb_pwm_request,
 358        .free = atmel_tcb_pwm_free,
 359        .config = atmel_tcb_pwm_config,
 360        .set_polarity = atmel_tcb_pwm_set_polarity,
 361        .enable = atmel_tcb_pwm_enable,
 362        .disable = atmel_tcb_pwm_disable,
 363        .owner = THIS_MODULE,
 364};
 365
 366static int atmel_tcb_pwm_probe(struct platform_device *pdev)
 367{
 368        struct atmel_tcb_pwm_chip *tcbpwm;
 369        struct device_node *np = pdev->dev.of_node;
 370        struct atmel_tc *tc;
 371        int err;
 372        int tcblock;
 373
 374        err = of_property_read_u32(np, "tc-block", &tcblock);
 375        if (err < 0) {
 376                dev_err(&pdev->dev,
 377                        "failed to get Timer Counter Block number from device tree (error: %d)\n",
 378                        err);
 379                return err;
 380        }
 381
 382        tc = atmel_tc_alloc(tcblock, "tcb-pwm");
 383        if (tc == NULL) {
 384                dev_err(&pdev->dev, "failed to allocate Timer Counter Block\n");
 385                return -ENOMEM;
 386        }
 387
 388        tcbpwm = devm_kzalloc(&pdev->dev, sizeof(*tcbpwm), GFP_KERNEL);
 389        if (tcbpwm == NULL) {
 390                atmel_tc_free(tc);
 391                dev_err(&pdev->dev, "failed to allocate memory\n");
 392                return -ENOMEM;
 393        }
 394
 395        tcbpwm->chip.dev = &pdev->dev;
 396        tcbpwm->chip.ops = &atmel_tcb_pwm_ops;
 397        tcbpwm->chip.of_xlate = of_pwm_xlate_with_flags;
 398        tcbpwm->chip.of_pwm_n_cells = 3;
 399        tcbpwm->chip.base = -1;
 400        tcbpwm->chip.npwm = NPWM;
 401        tcbpwm->tc = tc;
 402
 403        spin_lock_init(&tcbpwm->lock);
 404
 405        err = pwmchip_add(&tcbpwm->chip);
 406        if (err < 0) {
 407                atmel_tc_free(tc);
 408                return err;
 409        }
 410
 411        platform_set_drvdata(pdev, tcbpwm);
 412
 413        return 0;
 414}
 415
 416static int atmel_tcb_pwm_remove(struct platform_device *pdev)
 417{
 418        struct atmel_tcb_pwm_chip *tcbpwm = platform_get_drvdata(pdev);
 419        int err;
 420
 421        err = pwmchip_remove(&tcbpwm->chip);
 422        if (err < 0)
 423                return err;
 424
 425        atmel_tc_free(tcbpwm->tc);
 426
 427        return 0;
 428}
 429
 430static const struct of_device_id atmel_tcb_pwm_dt_ids[] = {
 431        { .compatible = "atmel,tcb-pwm", },
 432        { /* sentinel */ }
 433};
 434MODULE_DEVICE_TABLE(of, atmel_tcb_pwm_dt_ids);
 435
 436static struct platform_driver atmel_tcb_pwm_driver = {
 437        .driver = {
 438                .name = "atmel-tcb-pwm",
 439                .owner = THIS_MODULE,
 440                .of_match_table = atmel_tcb_pwm_dt_ids,
 441        },
 442        .probe = atmel_tcb_pwm_probe,
 443        .remove = atmel_tcb_pwm_remove,
 444};
 445module_platform_driver(atmel_tcb_pwm_driver);
 446
 447MODULE_AUTHOR("Boris BREZILLON <b.brezillon@overkiz.com>");
 448MODULE_DESCRIPTION("Atmel Timer Counter Pulse Width Modulation Driver");
 449MODULE_LICENSE("GPL v2");
 450