Quelle  pwm-atmel-tcb.c   Sprache: C

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) Overkiz SAS 2012
 *
 * Author: Boris BREZILLON <b.brezillon@overkiz.com>
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/clocksource.h>
#include <linux/clockchips.h>
#include <linux/interrupt.h>
#include <linux/irq.h>

#include <linux/clk.h>
#include <linux/err.h>
#include <linux/ioport.h>
#include <linux/io.h>
#include <linux/mfd/syscon.h>
#include <linux/platform_device.h>
#include <linux/pwm.h>
#include <linux/of.h>
#include <linux/regmap.h>
#include <linux/slab.h>
#include <soc/at91/atmel_tcb.h>

#define NPWM 2

#define ATMEL_TC_ACMR_MASK (ATMEL_TC_ACPA | ATMEL_TC_ACPC | \
     ATMEL_TC_AEEVT | ATMEL_TC_ASWTRG)

#define ATMEL_TC_BCMR_MASK (ATMEL_TC_BCPB | ATMEL_TC_BCPC | \
     ATMEL_TC_BEEVT | ATMEL_TC_BSWTRG)

struct atmel_tcb_pwm_device {
 unsigned div;   /* PWM clock divider */
 unsigned duty;   /* PWM duty expressed in clk cycles */
 unsigned period;  /* PWM period expressed in clk cycles */
};

struct atmel_tcb_channel {
 u32 enabled;
 u32 cmr;
 u32 ra;
 u32 rb;
 u32 rc;
};

struct atmel_tcb_pwm_chip {
 spinlock_t lock;
 u8 channel;
 u8 width;
 struct regmap *regmap;
 struct clk *clk;
 struct clk *gclk;
 struct clk *slow_clk;
 struct atmel_tcb_pwm_device pwms[NPWM];
 struct atmel_tcb_channel bkup;
};

static const u8 atmel_tcb_divisors[] = { 2, 8, 32, 128, 0, };

static inline struct atmel_tcb_pwm_chip *to_tcb_chip(struct pwm_chip *chip)
{
 return pwmchip_get_drvdata(chip);
}

static int atmel_tcb_pwm_request(struct pwm_chip *chip,
     struct pwm_device *pwm)
{
 struct atmel_tcb_pwm_chip *tcbpwmc = to_tcb_chip(chip);
 struct atmel_tcb_pwm_device *tcbpwm = &tcbpwmc->pwms[pwm->hwpwm];
 unsigned cmr;
 int ret;

 ret = clk_prepare_enable(tcbpwmc->clk);
 if (ret)
  return ret;

 tcbpwm->duty = 0;
 tcbpwm->period = 0;
 tcbpwm->div = 0;

 guard(spinlock)(&tcbpwmc->lock);

 regmap_read(tcbpwmc->regmap, ATMEL_TC_REG(tcbpwmc->channel, CMR), &cmr);
 /*
  * Get init config from Timer Counter registers if
  * Timer Counter is already configured as a PWM generator.
 */
 if (cmr & ATMEL_TC_WAVE) {
  if (pwm->hwpwm == 0)
   regmap_read(tcbpwmc->regmap,
        ATMEL_TC_REG(tcbpwmc->channel, RA),
        &tcbpwm->duty);
  else
   regmap_read(tcbpwmc->regmap,
        ATMEL_TC_REG(tcbpwmc->channel, RB),
        &tcbpwm->duty);

  tcbpwm->div = cmr & ATMEL_TC_TCCLKS;
  regmap_read(tcbpwmc->regmap, ATMEL_TC_REG(tcbpwmc->channel, RC),
       &tcbpwm->period);
  cmr &= (ATMEL_TC_TCCLKS | ATMEL_TC_ACMR_MASK |
   ATMEL_TC_BCMR_MASK);
 } else
  cmr = 0;

 cmr |= ATMEL_TC_WAVE | ATMEL_TC_WAVESEL_UP_AUTO | ATMEL_TC_EEVT_XC0;
 regmap_write(tcbpwmc->regmap, ATMEL_TC_REG(tcbpwmc->channel, CMR), cmr);

 return 0;
}

static void atmel_tcb_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
{
 struct atmel_tcb_pwm_chip *tcbpwmc = to_tcb_chip(chip);

 clk_disable_unprepare(tcbpwmc->clk);
}

static void atmel_tcb_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm,
      enum pwm_polarity polarity)
{
 struct atmel_tcb_pwm_chip *tcbpwmc = to_tcb_chip(chip);
 struct atmel_tcb_pwm_device *tcbpwm = &tcbpwmc->pwms[pwm->hwpwm];
 unsigned cmr;

 /*
  * If duty is 0 the timer will be stopped and we have to
  * configure the output correctly on software trigger:
  *  - set output to high if PWM_POLARITY_INVERSED
  *  - set output to low if PWM_POLARITY_NORMAL
  *
  * This is why we're reverting polarity in this case.
 */
 if (tcbpwm->duty == 0)
  polarity = !polarity;

 regmap_read(tcbpwmc->regmap, ATMEL_TC_REG(tcbpwmc->channel, CMR), &cmr);

 /* flush old setting and set the new one */
 if (pwm->hwpwm == 0) {
  cmr &= ~ATMEL_TC_ACMR_MASK;
  if (polarity == PWM_POLARITY_INVERSED)
   cmr |= ATMEL_TC_ASWTRG_CLEAR;
  else
   cmr |= ATMEL_TC_ASWTRG_SET;
 } else {
  cmr &= ~ATMEL_TC_BCMR_MASK;
  if (polarity == PWM_POLARITY_INVERSED)
   cmr |= ATMEL_TC_BSWTRG_CLEAR;
  else
   cmr |= ATMEL_TC_BSWTRG_SET;
 }

 regmap_write(tcbpwmc->regmap, ATMEL_TC_REG(tcbpwmc->channel, CMR), cmr);

 /*
  * Use software trigger to apply the new setting.
  * If both PWM devices in this group are disabled we stop the clock.
 */
 if (!(cmr & (ATMEL_TC_ACPC | ATMEL_TC_BCPC))) {
  regmap_write(tcbpwmc->regmap,
        ATMEL_TC_REG(tcbpwmc->channel, CCR),
        ATMEL_TC_SWTRG | ATMEL_TC_CLKDIS);
  tcbpwmc->bkup.enabled = 1;
 } else {
  regmap_write(tcbpwmc->regmap,
        ATMEL_TC_REG(tcbpwmc->channel, CCR),
        ATMEL_TC_SWTRG);
  tcbpwmc->bkup.enabled = 0;
 }
}

static int atmel_tcb_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm,
    enum pwm_polarity polarity)
{
 struct atmel_tcb_pwm_chip *tcbpwmc = to_tcb_chip(chip);
 struct atmel_tcb_pwm_device *tcbpwm = &tcbpwmc->pwms[pwm->hwpwm];
 u32 cmr;

 /*
  * If duty is 0 the timer will be stopped and we have to
  * configure the output correctly on software trigger:
  *  - set output to high if PWM_POLARITY_INVERSED
  *  - set output to low if PWM_POLARITY_NORMAL
  *
  * This is why we're reverting polarity in this case.
 */
 if (tcbpwm->duty == 0)
  polarity = !polarity;

 regmap_read(tcbpwmc->regmap, ATMEL_TC_REG(tcbpwmc->channel, CMR), &cmr);

 /* flush old setting and set the new one */
 cmr &= ~ATMEL_TC_TCCLKS;

 if (pwm->hwpwm == 0) {
  cmr &= ~ATMEL_TC_ACMR_MASK;

  /* Set CMR flags according to given polarity */
  if (polarity == PWM_POLARITY_INVERSED)
   cmr |= ATMEL_TC_ASWTRG_CLEAR;
  else
   cmr |= ATMEL_TC_ASWTRG_SET;
 } else {
  cmr &= ~ATMEL_TC_BCMR_MASK;
  if (polarity == PWM_POLARITY_INVERSED)
   cmr |= ATMEL_TC_BSWTRG_CLEAR;
  else
   cmr |= ATMEL_TC_BSWTRG_SET;
 }

 /*
  * If duty is 0 or equal to period there's no need to register
  * a specific action on RA/RB and RC compare.
  * The output will be configured on software trigger and keep
  * this config till next config call.
 */
 if (tcbpwm->duty != tcbpwm->period && tcbpwm->duty > 0) {
  if (pwm->hwpwm == 0) {
   if (polarity == PWM_POLARITY_INVERSED)
    cmr |= ATMEL_TC_ACPA_SET | ATMEL_TC_ACPC_CLEAR;
   else
    cmr |= ATMEL_TC_ACPA_CLEAR | ATMEL_TC_ACPC_SET;
  } else {
   if (polarity == PWM_POLARITY_INVERSED)
    cmr |= ATMEL_TC_BCPB_SET | ATMEL_TC_BCPC_CLEAR;
   else
    cmr |= ATMEL_TC_BCPB_CLEAR | ATMEL_TC_BCPC_SET;
  }
 }

 cmr |= (tcbpwm->div & ATMEL_TC_TCCLKS);

 regmap_write(tcbpwmc->regmap, ATMEL_TC_REG(tcbpwmc->channel, CMR), cmr);

 if (pwm->hwpwm == 0)
  regmap_write(tcbpwmc->regmap,
        ATMEL_TC_REG(tcbpwmc->channel, RA),
        tcbpwm->duty);
 else
  regmap_write(tcbpwmc->regmap,
        ATMEL_TC_REG(tcbpwmc->channel, RB),
        tcbpwm->duty);

 regmap_write(tcbpwmc->regmap, ATMEL_TC_REG(tcbpwmc->channel, RC),
       tcbpwm->period);

 /* Use software trigger to apply the new setting */
 regmap_write(tcbpwmc->regmap, ATMEL_TC_REG(tcbpwmc->channel, CCR),
       ATMEL_TC_SWTRG | ATMEL_TC_CLKEN);
 tcbpwmc->bkup.enabled = 1;
 return 0;
}

static int atmel_tcb_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
    int duty_ns, int period_ns)
{
 struct atmel_tcb_pwm_chip *tcbpwmc = to_tcb_chip(chip);
 struct atmel_tcb_pwm_device *tcbpwm = &tcbpwmc->pwms[pwm->hwpwm];
 /* companion PWM sharing register values period and div */
 struct atmel_tcb_pwm_device *atcbpwm = &tcbpwmc->pwms[pwm->hwpwm ^ 1];
 int i = 0;
 int slowclk = 0;
 unsigned period;
 unsigned duty;
 unsigned rate = clk_get_rate(tcbpwmc->clk);
 unsigned long long min;
 unsigned long long max;

 /*
  * Find best clk divisor:
  * the smallest divisor which can fulfill the period_ns requirements.
  * If there is a gclk, the first divisor is actually the gclk selector
 */
 if (tcbpwmc->gclk)
  i = 1;
 for (; i < ARRAY_SIZE(atmel_tcb_divisors); ++i) {
  if (atmel_tcb_divisors[i] == 0) {
   slowclk = i;
   continue;
  }
  min = div_u64((u64)NSEC_PER_SEC * atmel_tcb_divisors[i], rate);
  max = min << tcbpwmc->width;
  if (max >= period_ns)
   break;
 }

 /*
  * If none of the divisor are small enough to represent period_ns
  * take slow clock (32KHz).
 */
 if (i == ARRAY_SIZE(atmel_tcb_divisors)) {
  i = slowclk;
  rate = clk_get_rate(tcbpwmc->slow_clk);
  min = div_u64(NSEC_PER_SEC, rate);
  max = min << tcbpwmc->width;

  /* If period is too big return ERANGE error */
  if (max < period_ns)
   return -ERANGE;
 }

 duty = div_u64(duty_ns, min);
 period = div_u64(period_ns, min);

 /*
  * PWM devices provided by the TCB driver are grouped by 2.
  * PWM devices in a given group must be configured with the
  * same period_ns.
  *
  * We're checking the period value of the second PWM device
  * in this group before applying the new config.
 */
 if ((atcbpwm->duty > 0 && atcbpwm->duty != atcbpwm->period) &&
  (atcbpwm->div != i || atcbpwm->period != period)) {
  dev_err(pwmchip_parent(chip),
   "failed to configure period_ns: PWM group already configured with a different value\n");
  return -EINVAL;
 }

 tcbpwm->period = period;
 tcbpwm->div = i;
 tcbpwm->duty = duty;

 return 0;
}

static int atmel_tcb_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
          const struct pwm_state *state)
{
 struct atmel_tcb_pwm_chip *tcbpwmc = to_tcb_chip(chip);
 int duty_cycle, period;
 int ret;

 guard(spinlock)(&tcbpwmc->lock);

 if (!state->enabled) {
  atmel_tcb_pwm_disable(chip, pwm, state->polarity);
  return 0;
 }

 period = min(state->period, INT_MAX);
 duty_cycle = min(state->duty_cycle, INT_MAX);

 ret = atmel_tcb_pwm_config(chip, pwm, duty_cycle, period);
 if (ret)
  return ret;

 return atmel_tcb_pwm_enable(chip, pwm, state->polarity);
}

static const struct pwm_ops atmel_tcb_pwm_ops = {
 .request = atmel_tcb_pwm_request,
 .free = atmel_tcb_pwm_free,
 .apply = atmel_tcb_pwm_apply,
};

static struct atmel_tcb_config tcb_rm9200_config = {
 .counter_width = 16,
};

static struct atmel_tcb_config tcb_sam9x5_config = {
 .counter_width = 32,
};

static struct atmel_tcb_config tcb_sama5d2_config = {
 .counter_width = 32,
 .has_gclk = 1,
};

static const struct of_device_id atmel_tcb_of_match[] = {
 { .compatible = "atmel,at91rm9200-tcb", .data = &tcb_rm9200_config, },
 { .compatible = "atmel,at91sam9x5-tcb", .data = &tcb_sam9x5_config, },
 { .compatible = "atmel,sama5d2-tcb", .data = &tcb_sama5d2_config, },
 { /* sentinel */ }
};

static int atmel_tcb_pwm_probe(struct platform_device *pdev)
{
 struct pwm_chip *chip;
 const struct of_device_id *match;
 struct atmel_tcb_pwm_chip *tcbpwmc;
 const struct atmel_tcb_config *config;
 struct device_node *np = pdev->dev.of_node;
 char clk_name[] = "t0_clk";
 int err;
 int channel;

 chip = devm_pwmchip_alloc(&pdev->dev, NPWM, sizeof(*tcbpwmc));
 if (IS_ERR(chip))
  return PTR_ERR(chip);
 tcbpwmc = to_tcb_chip(chip);

 err = of_property_read_u32(np, "reg", &channel);
 if (err < 0) {
  dev_err(&pdev->dev,
   "failed to get Timer Counter Block channel from device tree (error: %d)\n",
   err);
  return err;
 }

 tcbpwmc->regmap = syscon_node_to_regmap(np->parent);
 if (IS_ERR(tcbpwmc->regmap))
  return PTR_ERR(tcbpwmc->regmap);

 tcbpwmc->slow_clk = of_clk_get_by_name(np->parent, "slow_clk");
 if (IS_ERR(tcbpwmc->slow_clk))
  return PTR_ERR(tcbpwmc->slow_clk);

 clk_name[1] += channel;
 tcbpwmc->clk = of_clk_get_by_name(np->parent, clk_name);
 if (IS_ERR(tcbpwmc->clk))
  tcbpwmc->clk = of_clk_get_by_name(np->parent, "t0_clk");
 if (IS_ERR(tcbpwmc->clk)) {
  err = PTR_ERR(tcbpwmc->clk);
  goto err_slow_clk;
 }

 match = of_match_node(atmel_tcb_of_match, np->parent);
 config = match->data;

 if (config->has_gclk) {
  tcbpwmc->gclk = of_clk_get_by_name(np->parent, "gclk");
  if (IS_ERR(tcbpwmc->gclk)) {
   err = PTR_ERR(tcbpwmc->gclk);
   goto err_clk;
  }
 }

 chip->ops = &atmel_tcb_pwm_ops;
 tcbpwmc->channel = channel;
 tcbpwmc->width = config->counter_width;

 err = clk_prepare_enable(tcbpwmc->slow_clk);
 if (err)
  goto err_gclk;

 spin_lock_init(&tcbpwmc->lock);

 err = pwmchip_add(chip);
 if (err < 0)
  goto err_disable_clk;

 platform_set_drvdata(pdev, chip);

 return 0;

err_disable_clk:
 clk_disable_unprepare(tcbpwmc->slow_clk);

err_gclk:
 clk_put(tcbpwmc->gclk);

err_clk:
 clk_put(tcbpwmc->clk);

err_slow_clk:
 clk_put(tcbpwmc->slow_clk);

 return err;
}

static void atmel_tcb_pwm_remove(struct platform_device *pdev)
{
 struct pwm_chip *chip = platform_get_drvdata(pdev);
 struct atmel_tcb_pwm_chip *tcbpwmc = to_tcb_chip(chip);

 pwmchip_remove(chip);

 clk_disable_unprepare(tcbpwmc->slow_clk);
 clk_put(tcbpwmc->gclk);
 clk_put(tcbpwmc->clk);
 clk_put(tcbpwmc->slow_clk);
}

static const struct of_device_id atmel_tcb_pwm_dt_ids[] = {
 { .compatible = "atmel,tcb-pwm", },
 { /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, atmel_tcb_pwm_dt_ids);

static int atmel_tcb_pwm_suspend(struct device *dev)
{
 struct pwm_chip *chip = dev_get_drvdata(dev);
 struct atmel_tcb_pwm_chip *tcbpwmc = to_tcb_chip(chip);
 struct atmel_tcb_channel *chan = &tcbpwmc->bkup;
 unsigned int channel = tcbpwmc->channel;

 regmap_read(tcbpwmc->regmap, ATMEL_TC_REG(channel, CMR), &chan->cmr);
 regmap_read(tcbpwmc->regmap, ATMEL_TC_REG(channel, RA), &chan->ra);
 regmap_read(tcbpwmc->regmap, ATMEL_TC_REG(channel, RB), &chan->rb);
 regmap_read(tcbpwmc->regmap, ATMEL_TC_REG(channel, RC), &chan->rc);

 return 0;
}

static int atmel_tcb_pwm_resume(struct device *dev)
{
 struct pwm_chip *chip = dev_get_drvdata(dev);
 struct atmel_tcb_pwm_chip *tcbpwmc = to_tcb_chip(chip);
 struct atmel_tcb_channel *chan = &tcbpwmc->bkup;
 unsigned int channel = tcbpwmc->channel;

 regmap_write(tcbpwmc->regmap, ATMEL_TC_REG(channel, CMR), chan->cmr);
 regmap_write(tcbpwmc->regmap, ATMEL_TC_REG(channel, RA), chan->ra);
 regmap_write(tcbpwmc->regmap, ATMEL_TC_REG(channel, RB), chan->rb);
 regmap_write(tcbpwmc->regmap, ATMEL_TC_REG(channel, RC), chan->rc);

 if (chan->enabled)
  regmap_write(tcbpwmc->regmap,
        ATMEL_TC_CLKEN | ATMEL_TC_SWTRG,
        ATMEL_TC_REG(channel, CCR));

 return 0;
}

static DEFINE_SIMPLE_DEV_PM_OPS(atmel_tcb_pwm_pm_ops, atmel_tcb_pwm_suspend,
    atmel_tcb_pwm_resume);

static struct platform_driver atmel_tcb_pwm_driver = {
 .driver = {
  .name = "atmel-tcb-pwm",
  .of_match_table = atmel_tcb_pwm_dt_ids,
  .pm = pm_ptr(&atmel_tcb_pwm_pm_ops),
 },
 .probe = atmel_tcb_pwm_probe,
 .remove = atmel_tcb_pwm_remove,
};
module_platform_driver(atmel_tcb_pwm_driver);

MODULE_AUTHOR("Boris BREZILLON <b.brezillon@overkiz.com>");
MODULE_DESCRIPTION("Atmel Timer Counter Pulse Width Modulation Driver");
MODULE_LICENSE("GPL v2");