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pwm.c

/* arch/arm/plat-s3c24xx/pwm.c
 *
 * Copyright (c) 2007 Ben Dooks
 * Copyright (c) 2008 Simtec Electronics
 *    Ben Dooks <ben@simtec.co.uk>, <ben-linux@fluff.org>
 *
 * S3C24XX PWM device core
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License.
*/

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/platform_device.h>
#include <linux/err.h>
#include <linux/clk.h>
#include <linux/io.h>
#include <linux/pwm.h>

#include <plat/devs.h>
#include <plat/regs-timer.h>

struct pwm_device {
      struct list_head   list;
      struct platform_device  *pdev;

      struct clk        *clk_div;
      struct clk        *clk;
      const char        *label;

      unsigned int             period_ns;
      unsigned int             duty_ns;

      unsigned char            tcon_base;
      unsigned char            running;
      unsigned char            use_count;
      unsigned char            pwm_id;
};

#define pwm_dbg(_pwm, msg...) dev_dbg(&(_pwm)->pdev->dev, msg)

static struct clk *clk_scaler[2];

/* Standard setup for a timer block. */

#define TIMER_RESOURCE_SIZE (1)

#define TIMER_RESOURCE(_tmr, _irq)              \
      (struct resource [TIMER_RESOURCE_SIZE]) { \
            [0] = {                             \
                  .start      = _irq,                 \
                  .end  = _irq,                 \
                  .flags      = IORESOURCE_IRQ  \
            }                             \
      }

#define DEFINE_S3C_TIMER(_tmr_no, _irq)               \
      .name       = "s3c24xx-pwm",        \
      .id         = _tmr_no,              \
      .num_resources    = TIMER_RESOURCE_SIZE,        \
      .resource   = TIMER_RESOURCE(_tmr_no, _irq),    \

/* since we already have an static mapping for the timer, we do not
 * bother setting any IO resource for the base.
 */

struct platform_device s3c_device_timer[] = {
      [0] = { DEFINE_S3C_TIMER(0, IRQ_TIMER0) },
      [1] = { DEFINE_S3C_TIMER(1, IRQ_TIMER1) },
      [2] = { DEFINE_S3C_TIMER(2, IRQ_TIMER2) },
      [3] = { DEFINE_S3C_TIMER(3, IRQ_TIMER3) },
      [4] = { DEFINE_S3C_TIMER(4, IRQ_TIMER4) },
};

static inline int pwm_is_tdiv(struct pwm_device *pwm)
{
      return clk_get_parent(pwm->clk) == pwm->clk_div;
}

static DEFINE_MUTEX(pwm_lock);
static LIST_HEAD(pwm_list);

struct pwm_device *pwm_request(int pwm_id, const char *label)
{
      struct pwm_device *pwm;
      int found = 0;

      mutex_lock(&pwm_lock);

      list_for_each_entry(pwm, &pwm_list, list) {
            if (pwm->pwm_id == pwm_id) {
                  found = 1;
                  break;
            }
      }

      if (found) {
            if (pwm->use_count == 0) {
                  pwm->use_count = 1;
                  pwm->label = label;
            } else
                  pwm = ERR_PTR(-EBUSY);
      } else
            pwm = ERR_PTR(-ENOENT);

      mutex_unlock(&pwm_lock);
      return pwm;
}

EXPORT_SYMBOL(pwm_request);


void pwm_free(struct pwm_device *pwm)
{
      mutex_lock(&pwm_lock);

      if (pwm->use_count) {
            pwm->use_count--;
            pwm->label = NULL;
      } else
            printk(KERN_ERR "PWM%d device already freed\n", pwm->pwm_id);

      mutex_unlock(&pwm_lock);
}

EXPORT_SYMBOL(pwm_free);

#define pwm_tcon_start(pwm) (1 << (pwm->tcon_base + 0))
#define pwm_tcon_invert(pwm) (1 << (pwm->tcon_base + 2))
#define pwm_tcon_autoreload(pwm) (1 << (pwm->tcon_base + 3))
#define pwm_tcon_manulupdate(pwm) (1 << (pwm->tcon_base + 1))

int pwm_enable(struct pwm_device *pwm)
{
      unsigned long flags;
      unsigned long tcon;

      local_irq_save(flags);

      tcon = __raw_readl(S3C2410_TCON);
      tcon |= pwm_tcon_start(pwm);
      __raw_writel(tcon, S3C2410_TCON);

      local_irq_restore(flags);

      pwm->running = 1;
      return 0;
}

EXPORT_SYMBOL(pwm_enable);

void pwm_disable(struct pwm_device *pwm)
{
      unsigned long flags;
      unsigned long tcon;

      local_irq_save(flags);

      tcon = __raw_readl(S3C2410_TCON);
      tcon &= ~pwm_tcon_start(pwm);
      __raw_writel(tcon, S3C2410_TCON);

      local_irq_restore(flags);

      pwm->running = 0;
}

EXPORT_SYMBOL(pwm_disable);

static unsigned long pwm_calc_tin(struct pwm_device *pwm, unsigned long freq)
{
      unsigned long tin_parent_rate;
      unsigned int div;

      tin_parent_rate = clk_get_rate(clk_get_parent(pwm->clk_div));
      pwm_dbg(pwm, "tin parent at %lu\n", tin_parent_rate);

      for (div = 2; div <= 16; div *= 2) {
            if ((tin_parent_rate / (div << 16)) < freq)
                  return tin_parent_rate / div;
      }

      return tin_parent_rate / 16;
}

#define NS_IN_HZ (1000000000UL)

int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
{
      unsigned long tin_rate;
      unsigned long tin_ns;
      unsigned long period;
      unsigned long flags;
      unsigned long tcon;
      unsigned long tcnt;
      long tcmp;

      /* We currently avoid using 64bit arithmetic by using the
       * fact that anything faster than 1Hz is easily representable
       * by 32bits. */

      if (period_ns > NS_IN_HZ || duty_ns > NS_IN_HZ)
            return -ERANGE;

      if (duty_ns > period_ns)
            return -EINVAL;

      if (period_ns == pwm->period_ns &&
          duty_ns == pwm->duty_ns)
            return 0;

      /* The TCMP and TCNT can be read without a lock, they're not
       * shared between the timers. */

      tcmp = __raw_readl(S3C2410_TCMPB(pwm->pwm_id));
      tcnt = __raw_readl(S3C2410_TCNTB(pwm->pwm_id));

      period = NS_IN_HZ / period_ns;

      pwm_dbg(pwm, "duty_ns=%d, period_ns=%d (%lu)\n",
            duty_ns, period_ns, period);

      /* Check to see if we are changing the clock rate of the PWM */

      if (pwm->period_ns != period_ns) {
            if (pwm_is_tdiv(pwm)) {
                  tin_rate = pwm_calc_tin(pwm, period);
                  clk_set_rate(pwm->clk_div, tin_rate);
            } else
                  tin_rate = clk_get_rate(pwm->clk);

            pwm->period_ns = period_ns;

            pwm_dbg(pwm, "tin_rate=%lu\n", tin_rate);

            tin_ns = NS_IN_HZ / tin_rate;
            tcnt = period_ns / tin_ns;
      } else
            tin_ns = NS_IN_HZ / clk_get_rate(pwm->clk);

      /* Note, counters count down */

      tcmp = duty_ns / tin_ns;
      tcmp = tcnt - tcmp;

      pwm_dbg(pwm, "tin_ns=%lu, tcmp=%ld/%lu\n", tin_ns, tcmp, tcnt);

      if (tcmp < 0)
            tcmp = 0;

      /* Update the PWM register block. */

      local_irq_save(flags);

      __raw_writel(tcmp, S3C2410_TCMPB(pwm->pwm_id));
      __raw_writel(tcnt, S3C2410_TCNTB(pwm->pwm_id));

      tcon = __raw_readl(S3C2410_TCON);
      tcon |= pwm_tcon_manulupdate(pwm);
      tcon |= pwm_tcon_autoreload(pwm);
      __raw_writel(tcon, S3C2410_TCON);

      tcon &= ~pwm_tcon_manulupdate(pwm);
      __raw_writel(tcon, S3C2410_TCON);

      local_irq_restore(flags);

      return 0;
}

EXPORT_SYMBOL(pwm_config);

static int pwm_register(struct pwm_device *pwm)
{
      pwm->duty_ns = -1;
      pwm->period_ns = -1;

      mutex_lock(&pwm_lock);
      list_add_tail(&pwm->list, &pwm_list);
      mutex_unlock(&pwm_lock);

      return 0;
}

static int s3c_pwm_probe(struct platform_device *pdev)
{
      struct device *dev = &pdev->dev;
      struct pwm_device *pwm;
      unsigned long flags;
      unsigned long tcon;
      unsigned int id = pdev->id;
      int ret;

      if (id == 4) {
            dev_err(dev, "TIMER4 is currently not supported\n");
            return -ENXIO;
      }

      pwm = kzalloc(sizeof(struct pwm_device), GFP_KERNEL);
      if (pwm == NULL) {
            dev_err(dev, "failed to allocate pwm_device\n");
            return -ENOMEM;
      }

      pwm->pdev = pdev;
      pwm->pwm_id = id;

      /* calculate base of control bits in TCON */
      pwm->tcon_base = id == 0 ? 0 : (id * 4) + 4;

      pwm->clk = clk_get(dev, "pwm-tin");
      if (IS_ERR(pwm->clk)) {
            dev_err(dev, "failed to get pwm tin clk\n");
            ret = PTR_ERR(pwm->clk);
            goto err_alloc;
      }

      pwm->clk_div = clk_get(dev, "pwm-tdiv");
      if (IS_ERR(pwm->clk_div)) {
            dev_err(dev, "failed to get pwm tdiv clk\n");
            ret = PTR_ERR(pwm->clk_div);
            goto err_clk_tin;
      }

      local_irq_save(flags);

      tcon = __raw_readl(S3C2410_TCON);
      tcon |= pwm_tcon_invert(pwm);
      __raw_writel(tcon, S3C2410_TCON);

      local_irq_restore(flags);


      ret = pwm_register(pwm);
      if (ret) {
            dev_err(dev, "failed to register pwm\n");
            goto err_clk_tdiv;
      }

      pwm_dbg(pwm, "config bits %02x\n",
            (__raw_readl(S3C2410_TCON) >> pwm->tcon_base) & 0x0f);

      dev_info(dev, "tin at %lu, tdiv at %lu, tin=%sclk, base %d\n",
             clk_get_rate(pwm->clk),
             clk_get_rate(pwm->clk_div),
             pwm_is_tdiv(pwm) ? "div" : "ext", pwm->tcon_base);

      platform_set_drvdata(pdev, pwm);
      return 0;

 err_clk_tdiv:
      clk_put(pwm->clk_div);

 err_clk_tin:
      clk_put(pwm->clk);

 err_alloc:
      kfree(pwm);
      return ret;
}

static int s3c_pwm_remove(struct platform_device *pdev)
{
      struct pwm_device *pwm = platform_get_drvdata(pdev);

      clk_put(pwm->clk_div);
      clk_put(pwm->clk);
      kfree(pwm);

      return 0;
}

static struct platform_driver s3c_pwm_driver = {
      .driver           = {
            .name = "s3c24xx-pwm",
            .owner      = THIS_MODULE,
      },
      .probe            = s3c_pwm_probe,
      .remove           = __devexit_p(s3c_pwm_remove),
};

static int __init pwm_init(void)
{
      int ret;

      clk_scaler[0] = clk_get(NULL, "pwm-scaler0");
      clk_scaler[1] = clk_get(NULL, "pwm-scaler1");

      if (IS_ERR(clk_scaler[0]) || IS_ERR(clk_scaler[1])) {
            printk(KERN_ERR "%s: failed to get scaler clocks\n", __func__);
            return -EINVAL;
      }

      ret = platform_driver_register(&s3c_pwm_driver);
      if (ret)
            printk(KERN_ERR "%s: failed to add pwm driver\n", __func__);

      return ret;
}

arch_initcall(pwm_init);

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