text: /*
   *  Cirrus Logic CLPS711X clocksource driver
   *
   *  Copyright (C) 2014 Alexander Shiyan <shc_work@mail.ru>
   *
   * 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.
   */
  
  #include <linux/clk.h>
  #include <linux/clockchips.h>
  #include <linux/clocksource.h>
  #include <linux/interrupt.h>
  #include <linux/io.h>
  #include <linux/of_address.h>
  #include <linux/of_irq.h>
  #include <linux/sched_clock.h>
  #include <linux/slab.h>
  
  enum {
  	CLPS711X_CLKSRC_CLOCKSOURCE,
  	CLPS711X_CLKSRC_CLOCKEVENT,
  };
  
  static void __iomem *tcd;
  
  static u64 notrace clps711x_sched_clock_read(void)
  {
  	return ~readw(tcd);
  }
  
  static int __init _clps711x_clksrc_init(struct clk *clock, void __iomem *base)
  {
  	unsigned long rate;
  
  	if (!base)
  		return -ENOMEM;
  	if (IS_ERR(clock))
  		return PTR_ERR(clock);
  
  	rate = clk_get_rate(clock);
  
  	tcd = base;
  
  	clocksource_mmio_init(tcd, "clps711x-clocksource", rate, 300, 16,
  			      clocksource_mmio_readw_down);
  
  	sched_clock_register(clps711x_sched_clock_read, 16, rate);
  
  	return 0;
  }
  
  static irqreturn_t clps711x_timer_interrupt(int irq, void *dev_id)
  {
  	struct clock_event_device *evt = dev_id;
  
  	evt->event_handler(evt);
  
  	return IRQ_HANDLED;
  }
  
  static int __init _clps711x_clkevt_init(struct clk *clock, void __iomem *base,
  					unsigned int irq)
  {
  	struct clock_event_device *clkevt;
  	unsigned long rate;
  
  	if (!irq)
  		return -EINVAL;
  	if (!base)
  		return -ENOMEM;
  	if (IS_ERR(clock))
  		return PTR_ERR(clock);
  
  	clkevt = kzalloc(sizeof(*clkevt), GFP_KERNEL);
  	if (!clkevt)
  		return -ENOMEM;
  
  	rate = clk_get_rate(clock);
  
  	/* Set Timer prescaler */
  	writew(DIV_ROUND_CLOSEST(rate, HZ), base);
  
  	clkevt->name = "clps711x-clockevent";
  	clkevt->rating = 300;
  	clkevt->features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_C3STOP;
  	clkevt->cpumask = cpumask_of(0);
  	clockevents_config_and_register(clkevt, HZ, 0, 0);
  
  	return request_irq(irq, clps711x_timer_interrupt, IRQF_TIMER,
  			   "clps711x-timer", clkevt);
  }
  
  void __init clps711x_clksrc_init(void __iomem *tc1_base, void __iomem *tc2_base,
  				 unsigned int irq)
  {
  	struct clk *tc1 = clk_get_sys("clps711x-timer.0", NULL);
  	struct clk *tc2 = clk_get_sys("clps711x-timer.1", NULL);
  
  	BUG_ON(_clps711x_clksrc_init(tc1, tc1_base));
  	BUG_ON(_clps711x_clkevt_init(tc2, tc2_base, irq));
  }
  
  #ifdef CONFIG_CLKSRC_OF
  static void __init clps711x_timer_init(struct device_node *np)
  {
  	unsigned int irq = irq_of_parse_and_map(np, 0);
  	struct clk *clock = of_clk_get(np, 0);
  	void __iomem *base = of_iomap(np, 0);
  
  	switch (of_alias_get_id(np, "timer")) {
  	case CLPS711X_CLKSRC_CLOCKSOURCE:
  		BUG_ON(_clps711x_clksrc_init(clock, base));
  		break;
  	case CLPS711X_CLKSRC_CLOCKEVENT:
  		BUG_ON(_clps711x_clkevt_init(clock, base, irq));
  		break;
  	default:
  		break;
  	}
  }
  CLOCKSOURCE_OF_DECLARE(clps711x, "cirrus,clps711x-timer", clps711x_timer_init);
  #endif
  