/*

   * Copyright (C) 2012 Altera Corporation

   * Copyright (c) 2011 Picochip Ltd., Jamie Iles
   *

   * Modified from mach-picoxcell/time.c
   *

   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2 as
   * published by the Free Software Foundation.
   *

   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program.  If not, see <http://www.gnu.org/licenses/>.

   */

  #include <linux/delay.h>

  #include <linux/dw_apb_timer.h>
  #include <linux/of.h>
  #include <linux/of_address.h>
  #include <linux/of_irq.h>

  #include <linux/clk.h>

  #include <linux/sched_clock.h>

  static void __init timer_get_base_and_rate(struct device_node *np,

  				    void __iomem **base, u32 *rate)
  {

  	struct clk *timer_clk;
  	struct clk *pclk;

  	*base = of_iomap(np, 0);
  
  	if (!*base)
  		panic("Unable to map regs for %s", np->name);

  	/*
  	 * Not all implementations use a periphal clock, so don't panic
  	 * if it's not present
  	 */
  	pclk = of_clk_get_by_name(np, "pclk");
  	if (!IS_ERR(pclk))
  		if (clk_prepare_enable(pclk))
  			pr_warn("pclk for %s is present, but could not be activated
  ",
  				np->name);
  
  	timer_clk = of_clk_get_by_name(np, "timer");
  	if (IS_ERR(timer_clk))
  		goto try_clock_freq;
  
  	if (!clk_prepare_enable(timer_clk)) {
  		*rate = clk_get_rate(timer_clk);
  		return;
  	}
  
  try_clock_freq:

  	if (of_property_read_u32(np, "clock-freq", rate) &&

  	    of_property_read_u32(np, "clock-frequency", rate))

  		panic("No clock nor clock-frequency property for %s", np->name);

  }

  static void __init add_clockevent(struct device_node *event_timer)

  {
  	void __iomem *iobase;
  	struct dw_apb_clock_event_device *ced;
  	u32 irq, rate;
  
  	irq = irq_of_parse_and_map(event_timer, 0);

  	if (irq == 0)

  		panic("No IRQ for clock event timer");
  
  	timer_get_base_and_rate(event_timer, &iobase, &rate);
  
  	ced = dw_apb_clockevent_init(0, event_timer->name, 300, iobase, irq,
  				     rate);
  	if (!ced)
  		panic("Unable to initialise clockevent device");
  
  	dw_apb_clockevent_register(ced);
  }

  static void __iomem *sched_io_base;
  static u32 sched_rate;

  static void __init add_clocksource(struct device_node *source_timer)

  {
  	void __iomem *iobase;
  	struct dw_apb_clocksource *cs;
  	u32 rate;
  
  	timer_get_base_and_rate(source_timer, &iobase, &rate);
  
  	cs = dw_apb_clocksource_init(300, source_timer->name, iobase, rate);
  	if (!cs)
  		panic("Unable to initialise clocksource device");
  
  	dw_apb_clocksource_start(cs);
  	dw_apb_clocksource_register(cs);

  	/*
  	 * Fallback to use the clocksource as sched_clock if no separate
  	 * timer is found. sched_io_base then points to the current_value
  	 * register of the clocksource timer.
  	 */
  	sched_io_base = iobase + 0x04;
  	sched_rate = rate;
  }

  static u64 notrace read_sched_clock(void)

  {

  	return ~readl_relaxed(sched_io_base);

  }

  static const struct of_device_id sptimer_ids[] __initconst = {

  	{ .compatible = "picochip,pc3x2-rtc" },
  	{ /* Sentinel */ },
  };

  static void __init init_sched_clock(void)

  {
  	struct device_node *sched_timer;

  	sched_timer = of_find_matching_node(NULL, sptimer_ids);

  	if (sched_timer) {
  		timer_get_base_and_rate(sched_timer, &sched_io_base,
  					&sched_rate);
  		of_node_put(sched_timer);
  	}

  	sched_clock_register(read_sched_clock, 32, sched_rate);

  }

  #ifdef CONFIG_ARM
  static unsigned long dw_apb_delay_timer_read(void)
  {
  	return ~readl_relaxed(sched_io_base);
  }
  
  static struct delay_timer dw_apb_delay_timer = {
  	.read_current_timer	= dw_apb_delay_timer_read,
  };
  #endif

  static int num_called;
  static void __init dw_apb_timer_init(struct device_node *timer)

  {

  	switch (num_called) {
  	case 0:
  		pr_debug("%s: found clockevent timer
  ", __func__);
  		add_clockevent(timer);

  		break;
  	case 1:
  		pr_debug("%s: found clocksource timer
  ", __func__);
  		add_clocksource(timer);

  		init_sched_clock();

  #ifdef CONFIG_ARM
  		dw_apb_delay_timer.freq = sched_rate;
  		register_current_timer_delay(&dw_apb_delay_timer);
  #endif

  		break;
  	default:
  		break;
  	}

  	num_called++;

  }

  CLOCKSOURCE_OF_DECLARE(pc3x2_timer, "picochip,pc3x2-timer", dw_apb_timer_init);

  CLOCKSOURCE_OF_DECLARE(apb_timer_osc, "snps,dw-apb-timer-osc", dw_apb_timer_init);
  CLOCKSOURCE_OF_DECLARE(apb_timer_sp, "snps,dw-apb-timer-sp", dw_apb_timer_init);
  CLOCKSOURCE_OF_DECLARE(apb_timer, "snps,dw-apb-timer", dw_apb_timer_init);