/* linux/arch/arm/mach-exynos4/mct.c
   *
   * Copyright (c) 2011 Samsung Electronics Co., Ltd.
   *		http://www.samsung.com
   *
   * EXYNOS4 MCT(Multi-Core Timer) support
   *
   * 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.
  */
  
  #include <linux/sched.h>
  #include <linux/interrupt.h>
  #include <linux/irq.h>
  #include <linux/err.h>
  #include <linux/clk.h>
  #include <linux/clockchips.h>
  #include <linux/platform_device.h>
  #include <linux/delay.h>
  #include <linux/percpu.h>

  #include <asm/hardware/gic.h>
  
  #include <plat/cpu.h>

  #include <mach/map.h>

  #include <mach/irqs.h>

  #include <mach/regs-mct.h>
  #include <asm/mach/time.h>

  enum {
  	MCT_INT_SPI,
  	MCT_INT_PPI
  };

  static unsigned long clk_cnt_per_tick;
  static unsigned long clk_rate;

  static unsigned int mct_int_type;

  
  struct mct_clock_event_device {
  	struct clock_event_device *evt;
  	void __iomem *base;

  	char name[10];

  };

  static void exynos4_mct_write(unsigned int value, void *addr)
  {
  	void __iomem *stat_addr;
  	u32 mask;
  	u32 i;
  
  	__raw_writel(value, addr);

  	if (likely(addr >= EXYNOS4_MCT_L_BASE(0))) {
  		u32 base = (u32) addr & EXYNOS4_MCT_L_MASK;
  		switch ((u32) addr & ~EXYNOS4_MCT_L_MASK) {
  		case (u32) MCT_L_TCON_OFFSET:
  			stat_addr = (void __iomem *) base + MCT_L_WSTAT_OFFSET;
  			mask = 1 << 3;		/* L_TCON write status */
  			break;
  		case (u32) MCT_L_ICNTB_OFFSET:
  			stat_addr = (void __iomem *) base + MCT_L_WSTAT_OFFSET;
  			mask = 1 << 1;		/* L_ICNTB write status */
  			break;
  		case (u32) MCT_L_TCNTB_OFFSET:
  			stat_addr = (void __iomem *) base + MCT_L_WSTAT_OFFSET;
  			mask = 1 << 0;		/* L_TCNTB write status */
  			break;
  		default:
  			return;
  		}
  	} else {
  		switch ((u32) addr) {
  		case (u32) EXYNOS4_MCT_G_TCON:
  			stat_addr = EXYNOS4_MCT_G_WSTAT;
  			mask = 1 << 16;		/* G_TCON write status */
  			break;
  		case (u32) EXYNOS4_MCT_G_COMP0_L:
  			stat_addr = EXYNOS4_MCT_G_WSTAT;
  			mask = 1 << 0;		/* G_COMP0_L write status */
  			break;
  		case (u32) EXYNOS4_MCT_G_COMP0_U:
  			stat_addr = EXYNOS4_MCT_G_WSTAT;
  			mask = 1 << 1;		/* G_COMP0_U write status */
  			break;
  		case (u32) EXYNOS4_MCT_G_COMP0_ADD_INCR:
  			stat_addr = EXYNOS4_MCT_G_WSTAT;
  			mask = 1 << 2;		/* G_COMP0_ADD_INCR w status */
  			break;
  		case (u32) EXYNOS4_MCT_G_CNT_L:
  			stat_addr = EXYNOS4_MCT_G_CNT_WSTAT;
  			mask = 1 << 0;		/* G_CNT_L write status */
  			break;
  		case (u32) EXYNOS4_MCT_G_CNT_U:
  			stat_addr = EXYNOS4_MCT_G_CNT_WSTAT;
  			mask = 1 << 1;		/* G_CNT_U write status */
  			break;
  		default:
  			return;
  		}

  	}
  
  	/* Wait maximum 1 ms until written values are applied */
  	for (i = 0; i < loops_per_jiffy / 1000 * HZ; i++)
  		if (__raw_readl(stat_addr) & mask) {
  			__raw_writel(mask, stat_addr);
  			return;
  		}
  
  	panic("MCT hangs after writing %d (addr:0x%08x)
  ", value, (u32)addr);
  }
  
  /* Clocksource handling */
  static void exynos4_mct_frc_start(u32 hi, u32 lo)
  {
  	u32 reg;
  
  	exynos4_mct_write(lo, EXYNOS4_MCT_G_CNT_L);
  	exynos4_mct_write(hi, EXYNOS4_MCT_G_CNT_U);
  
  	reg = __raw_readl(EXYNOS4_MCT_G_TCON);
  	reg |= MCT_G_TCON_START;
  	exynos4_mct_write(reg, EXYNOS4_MCT_G_TCON);
  }
  
  static cycle_t exynos4_frc_read(struct clocksource *cs)
  {
  	unsigned int lo, hi;
  	u32 hi2 = __raw_readl(EXYNOS4_MCT_G_CNT_U);
  
  	do {
  		hi = hi2;
  		lo = __raw_readl(EXYNOS4_MCT_G_CNT_L);
  		hi2 = __raw_readl(EXYNOS4_MCT_G_CNT_U);
  	} while (hi != hi2);
  
  	return ((cycle_t)hi << 32) | lo;
  }

  static void exynos4_frc_resume(struct clocksource *cs)
  {
  	exynos4_mct_frc_start(0, 0);
  }

  struct clocksource mct_frc = {
  	.name		= "mct-frc",
  	.rating		= 400,
  	.read		= exynos4_frc_read,
  	.mask		= CLOCKSOURCE_MASK(64),
  	.flags		= CLOCK_SOURCE_IS_CONTINUOUS,

  	.resume		= exynos4_frc_resume,

  };
  
  static void __init exynos4_clocksource_init(void)
  {
  	exynos4_mct_frc_start(0, 0);
  
  	if (clocksource_register_hz(&mct_frc, clk_rate))
  		panic("%s: can't register clocksource
  ", mct_frc.name);
  }
  
  static void exynos4_mct_comp0_stop(void)
  {
  	unsigned int tcon;
  
  	tcon = __raw_readl(EXYNOS4_MCT_G_TCON);
  	tcon &= ~(MCT_G_TCON_COMP0_ENABLE | MCT_G_TCON_COMP0_AUTO_INC);
  
  	exynos4_mct_write(tcon, EXYNOS4_MCT_G_TCON);
  	exynos4_mct_write(0, EXYNOS4_MCT_G_INT_ENB);
  }
  
  static void exynos4_mct_comp0_start(enum clock_event_mode mode,
  				    unsigned long cycles)
  {
  	unsigned int tcon;
  	cycle_t comp_cycle;
  
  	tcon = __raw_readl(EXYNOS4_MCT_G_TCON);
  
  	if (mode == CLOCK_EVT_MODE_PERIODIC) {
  		tcon |= MCT_G_TCON_COMP0_AUTO_INC;
  		exynos4_mct_write(cycles, EXYNOS4_MCT_G_COMP0_ADD_INCR);
  	}
  
  	comp_cycle = exynos4_frc_read(&mct_frc) + cycles;
  	exynos4_mct_write((u32)comp_cycle, EXYNOS4_MCT_G_COMP0_L);
  	exynos4_mct_write((u32)(comp_cycle >> 32), EXYNOS4_MCT_G_COMP0_U);
  
  	exynos4_mct_write(0x1, EXYNOS4_MCT_G_INT_ENB);
  
  	tcon |= MCT_G_TCON_COMP0_ENABLE;
  	exynos4_mct_write(tcon , EXYNOS4_MCT_G_TCON);
  }
  
  static int exynos4_comp_set_next_event(unsigned long cycles,
  				       struct clock_event_device *evt)
  {
  	exynos4_mct_comp0_start(evt->mode, cycles);
  
  	return 0;
  }
  
  static void exynos4_comp_set_mode(enum clock_event_mode mode,
  				  struct clock_event_device *evt)
  {
  	exynos4_mct_comp0_stop();
  
  	switch (mode) {
  	case CLOCK_EVT_MODE_PERIODIC:
  		exynos4_mct_comp0_start(mode, clk_cnt_per_tick);
  		break;
  
  	case CLOCK_EVT_MODE_ONESHOT:
  	case CLOCK_EVT_MODE_UNUSED:
  	case CLOCK_EVT_MODE_SHUTDOWN:
  	case CLOCK_EVT_MODE_RESUME:
  		break;
  	}
  }
  
  static struct clock_event_device mct_comp_device = {
  	.name		= "mct-comp",
  	.features       = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
  	.rating		= 250,
  	.set_next_event	= exynos4_comp_set_next_event,
  	.set_mode	= exynos4_comp_set_mode,
  };
  
  static irqreturn_t exynos4_mct_comp_isr(int irq, void *dev_id)
  {
  	struct clock_event_device *evt = dev_id;
  
  	exynos4_mct_write(0x1, EXYNOS4_MCT_G_INT_CSTAT);
  
  	evt->event_handler(evt);
  
  	return IRQ_HANDLED;
  }
  
  static struct irqaction mct_comp_event_irq = {
  	.name		= "mct_comp_irq",
  	.flags		= IRQF_TIMER | IRQF_IRQPOLL,
  	.handler	= exynos4_mct_comp_isr,
  	.dev_id		= &mct_comp_device,
  };
  
  static void exynos4_clockevent_init(void)
  {
  	clk_cnt_per_tick = clk_rate / 2	/ HZ;
  
  	clockevents_calc_mult_shift(&mct_comp_device, clk_rate / 2, 5);
  	mct_comp_device.max_delta_ns =
  		clockevent_delta2ns(0xffffffff, &mct_comp_device);
  	mct_comp_device.min_delta_ns =
  		clockevent_delta2ns(0xf, &mct_comp_device);
  	mct_comp_device.cpumask = cpumask_of(0);
  	clockevents_register_device(&mct_comp_device);
  
  	setup_irq(IRQ_MCT_G0, &mct_comp_event_irq);
  }
  
  #ifdef CONFIG_LOCAL_TIMERS

  
  static DEFINE_PER_CPU(struct mct_clock_event_device, percpu_mct_tick);

  /* Clock event handling */
  static void exynos4_mct_tick_stop(struct mct_clock_event_device *mevt)
  {
  	unsigned long tmp;
  	unsigned long mask = MCT_L_TCON_INT_START | MCT_L_TCON_TIMER_START;
  	void __iomem *addr = mevt->base + MCT_L_TCON_OFFSET;
  
  	tmp = __raw_readl(addr);
  	if (tmp & mask) {
  		tmp &= ~mask;
  		exynos4_mct_write(tmp, addr);
  	}
  }
  
  static void exynos4_mct_tick_start(unsigned long cycles,
  				   struct mct_clock_event_device *mevt)
  {
  	unsigned long tmp;
  
  	exynos4_mct_tick_stop(mevt);
  
  	tmp = (1 << 31) | cycles;	/* MCT_L_UPDATE_ICNTB */
  
  	/* update interrupt count buffer */
  	exynos4_mct_write(tmp, mevt->base + MCT_L_ICNTB_OFFSET);

  	/* enable MCT tick interrupt */

  	exynos4_mct_write(0x1, mevt->base + MCT_L_INT_ENB_OFFSET);
  
  	tmp = __raw_readl(mevt->base + MCT_L_TCON_OFFSET);
  	tmp |= MCT_L_TCON_INT_START | MCT_L_TCON_TIMER_START |
  	       MCT_L_TCON_INTERVAL_MODE;
  	exynos4_mct_write(tmp, mevt->base + MCT_L_TCON_OFFSET);
  }
  
  static int exynos4_tick_set_next_event(unsigned long cycles,
  				       struct clock_event_device *evt)
  {

  	struct mct_clock_event_device *mevt = this_cpu_ptr(&percpu_mct_tick);

  
  	exynos4_mct_tick_start(cycles, mevt);
  
  	return 0;
  }
  
  static inline void exynos4_tick_set_mode(enum clock_event_mode mode,
  					 struct clock_event_device *evt)
  {

  	struct mct_clock_event_device *mevt = this_cpu_ptr(&percpu_mct_tick);

  
  	exynos4_mct_tick_stop(mevt);
  
  	switch (mode) {
  	case CLOCK_EVT_MODE_PERIODIC:
  		exynos4_mct_tick_start(clk_cnt_per_tick, mevt);
  		break;
  
  	case CLOCK_EVT_MODE_ONESHOT:
  	case CLOCK_EVT_MODE_UNUSED:
  	case CLOCK_EVT_MODE_SHUTDOWN:
  	case CLOCK_EVT_MODE_RESUME:
  		break;
  	}
  }

  static int exynos4_mct_tick_clear(struct mct_clock_event_device *mevt)

  {

  	struct clock_event_device *evt = mevt->evt;
  
  	/*
  	 * This is for supporting oneshot mode.
  	 * Mct would generate interrupt periodically
  	 * without explicit stopping.
  	 */
  	if (evt->mode != CLOCK_EVT_MODE_PERIODIC)
  		exynos4_mct_tick_stop(mevt);
  
  	/* Clear the MCT tick interrupt */

  	if (__raw_readl(mevt->base + MCT_L_INT_CSTAT_OFFSET) & 1) {
  		exynos4_mct_write(0x1, mevt->base + MCT_L_INT_CSTAT_OFFSET);
  		return 1;
  	} else {
  		return 0;
  	}
  }
  
  static irqreturn_t exynos4_mct_tick_isr(int irq, void *dev_id)
  {
  	struct mct_clock_event_device *mevt = dev_id;
  	struct clock_event_device *evt = mevt->evt;
  
  	exynos4_mct_tick_clear(mevt);

  
  	evt->event_handler(evt);
  
  	return IRQ_HANDLED;
  }
  
  static struct irqaction mct_tick0_event_irq = {
  	.name		= "mct_tick0_irq",
  	.flags		= IRQF_TIMER | IRQF_NOBALANCING,
  	.handler	= exynos4_mct_tick_isr,
  };
  
  static struct irqaction mct_tick1_event_irq = {
  	.name		= "mct_tick1_irq",
  	.flags		= IRQF_TIMER | IRQF_NOBALANCING,
  	.handler	= exynos4_mct_tick_isr,
  };
  
  static void exynos4_mct_tick_init(struct clock_event_device *evt)
  {

  	struct mct_clock_event_device *mevt;

  	unsigned int cpu = smp_processor_id();

  	mevt = this_cpu_ptr(&percpu_mct_tick);
  	mevt->evt = evt;

  	mevt->base = EXYNOS4_MCT_L_BASE(cpu);
  	sprintf(mevt->name, "mct_tick%d", cpu);

  	evt->name = mevt->name;

  	evt->cpumask = cpumask_of(cpu);
  	evt->set_next_event = exynos4_tick_set_next_event;
  	evt->set_mode = exynos4_tick_set_mode;
  	evt->features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT;
  	evt->rating = 450;
  
  	clockevents_calc_mult_shift(evt, clk_rate / 2, 5);
  	evt->max_delta_ns =
  		clockevent_delta2ns(0x7fffffff, evt);
  	evt->min_delta_ns =
  		clockevent_delta2ns(0xf, evt);
  
  	clockevents_register_device(evt);

  	exynos4_mct_write(0x1, mevt->base + MCT_L_TCNTB_OFFSET);

  	if (mct_int_type == MCT_INT_SPI) {
  		if (cpu == 0) {

  			mct_tick0_event_irq.dev_id = mevt;

  			evt->irq = IRQ_MCT_L0;

  			setup_irq(IRQ_MCT_L0, &mct_tick0_event_irq);
  		} else {

  			mct_tick1_event_irq.dev_id = mevt;

  			evt->irq = IRQ_MCT_L1;

  			setup_irq(IRQ_MCT_L1, &mct_tick1_event_irq);
  			irq_set_affinity(IRQ_MCT_L1, cpumask_of(1));
  		}

  	} else {

  		enable_percpu_irq(IRQ_MCT_LOCALTIMER, 0);

  	}
  }
  
  /* Setup the local clock events for a CPU */

  int __cpuinit local_timer_setup(struct clock_event_device *evt)

  {
  	exynos4_mct_tick_init(evt);

  
  	return 0;

  }

  void local_timer_stop(struct clock_event_device *evt)

  {

  	unsigned int cpu = smp_processor_id();

  	evt->set_mode(CLOCK_EVT_MODE_UNUSED, evt);

  	if (mct_int_type == MCT_INT_SPI)

  		if (cpu == 0)
  			remove_irq(evt->irq, &mct_tick0_event_irq);
  		else
  			remove_irq(evt->irq, &mct_tick1_event_irq);

  	else
  		disable_percpu_irq(IRQ_MCT_LOCALTIMER);

  }

  #endif /* CONFIG_LOCAL_TIMERS */
  
  static void __init exynos4_timer_resources(void)
  {
  	struct clk *mct_clk;
  	mct_clk = clk_get(NULL, "xtal");
  
  	clk_rate = clk_get_rate(mct_clk);

  #ifdef CONFIG_LOCAL_TIMERS

  	if (mct_int_type == MCT_INT_PPI) {
  		int err;
  
  		err = request_percpu_irq(IRQ_MCT_LOCALTIMER,
  					 exynos4_mct_tick_isr, "MCT",
  					 &percpu_mct_tick);
  		WARN(err, "MCT: can't request IRQ %d (%d)
  ",
  		     IRQ_MCT_LOCALTIMER, err);
  	}

  #endif /* CONFIG_LOCAL_TIMERS */

  }
  
  static void __init exynos4_timer_init(void)
  {

  	if (soc_is_exynos4210())
  		mct_int_type = MCT_INT_SPI;
  	else
  		mct_int_type = MCT_INT_PPI;

  	exynos4_timer_resources();
  	exynos4_clocksource_init();
  	exynos4_clockevent_init();
  }
  
  struct sys_timer exynos4_timer = {
  	.init		= exynos4_timer_init,
  };