/*
   *  Copyright (C) 2010, Lars-Peter Clausen <lars@metafoo.de>
   *  JZ4740 platform PWM support
   *
   *  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, or (at your
   *  option) any later version.
   *
   *  You should have received a copy of the GNU General Public License along
   *  with this program; if not, write to the Free Software Foundation, Inc.,
   *  675 Mass Ave, Cambridge, MA 02139, USA.
   *
   */
  
  #include <linux/kernel.h>
  
  #include <linux/clk.h>
  #include <linux/err.h>
  #include <linux/pwm.h>
  #include <linux/gpio.h>
  
  #include <asm/mach-jz4740/gpio.h>
  #include "timer.h"
  
  static struct clk *jz4740_pwm_clk;
  
  DEFINE_MUTEX(jz4740_pwm_mutex);
  
  struct pwm_device {
  	unsigned int id;
  	unsigned int gpio;
  	bool used;
  };
  
  static struct pwm_device jz4740_pwm_list[] = {
  	{ 2, JZ_GPIO_PWM2, false },
  	{ 3, JZ_GPIO_PWM3, false },
  	{ 4, JZ_GPIO_PWM4, false },
  	{ 5, JZ_GPIO_PWM5, false },
  	{ 6, JZ_GPIO_PWM6, false },
  	{ 7, JZ_GPIO_PWM7, false },
  };
  
  struct pwm_device *pwm_request(int id, const char *label)
  {
  	int ret = 0;
  	struct pwm_device *pwm;
  
  	if (id < 2 || id > 7 || !jz4740_pwm_clk)
  		return ERR_PTR(-ENODEV);
  
  	mutex_lock(&jz4740_pwm_mutex);
  
  	pwm = &jz4740_pwm_list[id - 2];
  	if (pwm->used)
  		ret = -EBUSY;
  	else
  		pwm->used = true;
  
  	mutex_unlock(&jz4740_pwm_mutex);
  
  	if (ret)
  		return ERR_PTR(ret);
  
  	ret = gpio_request(pwm->gpio, label);
  
  	if (ret) {
  		printk(KERN_ERR "Failed to request pwm gpio: %d
  ", ret);
  		pwm->used = false;
  		return ERR_PTR(ret);
  	}
  
  	jz_gpio_set_function(pwm->gpio, JZ_GPIO_FUNC_PWM);
  
  	jz4740_timer_start(id);
  
  	return pwm;
  }
  
  void pwm_free(struct pwm_device *pwm)
  {
  	pwm_disable(pwm);
  	jz4740_timer_set_ctrl(pwm->id, 0);
  
  	jz_gpio_set_function(pwm->gpio, JZ_GPIO_FUNC_NONE);
  	gpio_free(pwm->gpio);
  
  	jz4740_timer_stop(pwm->id);
  
  	pwm->used = false;
  }
  
  int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
  {
  	unsigned long long tmp;
  	unsigned long period, duty;
  	unsigned int prescaler = 0;
  	unsigned int id = pwm->id;
  	uint16_t ctrl;
  	bool is_enabled;
  
  	if (duty_ns < 0 || duty_ns > period_ns)
  		return -EINVAL;
  
  	tmp = (unsigned long long)clk_get_rate(jz4740_pwm_clk) * period_ns;
  	do_div(tmp, 1000000000);
  	period = tmp;
  
  	while (period > 0xffff && prescaler < 6) {
  		period >>= 2;
  		++prescaler;
  	}
  
  	if (prescaler == 6)
  		return -EINVAL;
  
  	tmp = (unsigned long long)period * duty_ns;
  	do_div(tmp, period_ns);
  	duty = period - tmp;
  
  	if (duty >= period)
  		duty = period - 1;
  
  	is_enabled = jz4740_timer_is_enabled(id);
  	if (is_enabled)
  		pwm_disable(pwm);
  
  	jz4740_timer_set_count(id, 0);
  	jz4740_timer_set_duty(id, duty);
  	jz4740_timer_set_period(id, period);
  
  	ctrl = JZ_TIMER_CTRL_PRESCALER(prescaler) | JZ_TIMER_CTRL_SRC_EXT |
  		JZ_TIMER_CTRL_PWM_ABBRUPT_SHUTDOWN;
  
  	jz4740_timer_set_ctrl(id, ctrl);
  
  	if (is_enabled)
  		pwm_enable(pwm);
  
  	return 0;
  }
  
  int pwm_enable(struct pwm_device *pwm)
  {
  	uint32_t ctrl = jz4740_timer_get_ctrl(pwm->id);
  
  	ctrl |= JZ_TIMER_CTRL_PWM_ENABLE;
  	jz4740_timer_set_ctrl(pwm->id, ctrl);
  	jz4740_timer_enable(pwm->id);
  
  	return 0;
  }
  
  void pwm_disable(struct pwm_device *pwm)
  {
  	uint32_t ctrl = jz4740_timer_get_ctrl(pwm->id);
  
  	ctrl &= ~JZ_TIMER_CTRL_PWM_ENABLE;
  	jz4740_timer_disable(pwm->id);
  	jz4740_timer_set_ctrl(pwm->id, ctrl);
  }
  
  static int __init jz4740_pwm_init(void)
  {
  	int ret = 0;
  
  	jz4740_pwm_clk = clk_get(NULL, "ext");
  
  	if (IS_ERR(jz4740_pwm_clk)) {
  		ret = PTR_ERR(jz4740_pwm_clk);
  		jz4740_pwm_clk = NULL;
  	}
  
  	return ret;
  }
  subsys_initcall(jz4740_pwm_init);