/* 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/cpu.h>

  #include <linux/platform_device.h>
  #include <linux/delay.h>
  #include <linux/percpu.h>

  #include <linux/of.h>

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

  #include <linux/clocksource.h>

  #include <linux/sched_clock.h>

  #define EXYNOS4_MCTREG(x)		(x)
  #define EXYNOS4_MCT_G_CNT_L		EXYNOS4_MCTREG(0x100)
  #define EXYNOS4_MCT_G_CNT_U		EXYNOS4_MCTREG(0x104)
  #define EXYNOS4_MCT_G_CNT_WSTAT		EXYNOS4_MCTREG(0x110)
  #define EXYNOS4_MCT_G_COMP0_L		EXYNOS4_MCTREG(0x200)
  #define EXYNOS4_MCT_G_COMP0_U		EXYNOS4_MCTREG(0x204)
  #define EXYNOS4_MCT_G_COMP0_ADD_INCR	EXYNOS4_MCTREG(0x208)
  #define EXYNOS4_MCT_G_TCON		EXYNOS4_MCTREG(0x240)
  #define EXYNOS4_MCT_G_INT_CSTAT		EXYNOS4_MCTREG(0x244)
  #define EXYNOS4_MCT_G_INT_ENB		EXYNOS4_MCTREG(0x248)
  #define EXYNOS4_MCT_G_WSTAT		EXYNOS4_MCTREG(0x24C)
  #define _EXYNOS4_MCT_L_BASE		EXYNOS4_MCTREG(0x300)
  #define EXYNOS4_MCT_L_BASE(x)		(_EXYNOS4_MCT_L_BASE + (0x100 * x))
  #define EXYNOS4_MCT_L_MASK		(0xffffff00)
  
  #define MCT_L_TCNTB_OFFSET		(0x00)
  #define MCT_L_ICNTB_OFFSET		(0x08)
  #define MCT_L_TCON_OFFSET		(0x20)
  #define MCT_L_INT_CSTAT_OFFSET		(0x30)
  #define MCT_L_INT_ENB_OFFSET		(0x34)
  #define MCT_L_WSTAT_OFFSET		(0x40)
  #define MCT_G_TCON_START		(1 << 8)
  #define MCT_G_TCON_COMP0_AUTO_INC	(1 << 1)
  #define MCT_G_TCON_COMP0_ENABLE		(1 << 0)
  #define MCT_L_TCON_INTERVAL_MODE	(1 << 2)
  #define MCT_L_TCON_INT_START		(1 << 1)
  #define MCT_L_TCON_TIMER_START		(1 << 0)

  #define TICK_BASE_CNT	1

  enum {
  	MCT_INT_SPI,
  	MCT_INT_PPI
  };

  enum {
  	MCT_G0_IRQ,
  	MCT_G1_IRQ,
  	MCT_G2_IRQ,
  	MCT_G3_IRQ,
  	MCT_L0_IRQ,
  	MCT_L1_IRQ,
  	MCT_L2_IRQ,
  	MCT_L3_IRQ,

  	MCT_L4_IRQ,
  	MCT_L5_IRQ,
  	MCT_L6_IRQ,
  	MCT_L7_IRQ,

  	MCT_NR_IRQS,
  };

  static void __iomem *reg_base;

  static unsigned long clk_rate;

  static unsigned int mct_int_type;

  static int mct_irqs[MCT_NR_IRQS];

  
  struct mct_clock_event_device {

  	struct clock_event_device evt;

  	unsigned long base;

  	char name[10];

  };

  static void exynos4_mct_write(unsigned int value, unsigned long offset)

  {

  	unsigned long stat_addr;

  	u32 mask;
  	u32 i;

  	writel_relaxed(value, reg_base + offset);

  	if (likely(offset >= EXYNOS4_MCT_L_BASE(0))) {

  		stat_addr = (offset & EXYNOS4_MCT_L_MASK) + MCT_L_WSTAT_OFFSET;
  		switch (offset & ~EXYNOS4_MCT_L_MASK) {

  		case MCT_L_TCON_OFFSET:

  			mask = 1 << 3;		/* L_TCON write status */
  			break;

  		case MCT_L_ICNTB_OFFSET:

  			mask = 1 << 1;		/* L_ICNTB write status */
  			break;

  		case MCT_L_TCNTB_OFFSET:

  			mask = 1 << 0;		/* L_TCNTB write status */
  			break;
  		default:
  			return;
  		}
  	} else {

  		switch (offset) {
  		case EXYNOS4_MCT_G_TCON:

  			stat_addr = EXYNOS4_MCT_G_WSTAT;
  			mask = 1 << 16;		/* G_TCON write status */
  			break;

  		case EXYNOS4_MCT_G_COMP0_L:

  			stat_addr = EXYNOS4_MCT_G_WSTAT;
  			mask = 1 << 0;		/* G_COMP0_L write status */
  			break;

  		case EXYNOS4_MCT_G_COMP0_U:

  			stat_addr = EXYNOS4_MCT_G_WSTAT;
  			mask = 1 << 1;		/* G_COMP0_U write status */
  			break;

  		case EXYNOS4_MCT_G_COMP0_ADD_INCR:

  			stat_addr = EXYNOS4_MCT_G_WSTAT;
  			mask = 1 << 2;		/* G_COMP0_ADD_INCR w status */
  			break;

  		case EXYNOS4_MCT_G_CNT_L:

  			stat_addr = EXYNOS4_MCT_G_CNT_WSTAT;
  			mask = 1 << 0;		/* G_CNT_L write status */
  			break;

  		case 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 (readl_relaxed(reg_base + stat_addr) & mask) {
  			writel_relaxed(mask, reg_base + stat_addr);

  			return;
  		}

  	panic("MCT hangs after writing %d (offset:0x%lx)
  ", value, offset);

  }
  
  /* Clocksource handling */

  static void exynos4_mct_frc_start(void)

  {
  	u32 reg;

  	reg = readl_relaxed(reg_base + EXYNOS4_MCT_G_TCON);

  	reg |= MCT_G_TCON_START;
  	exynos4_mct_write(reg, EXYNOS4_MCT_G_TCON);
  }

  /**
   * exynos4_read_count_64 - Read all 64-bits of the global counter
   *
   * This will read all 64-bits of the global counter taking care to make sure
   * that the upper and lower half match.  Note that reading the MCT can be quite
   * slow (hundreds of nanoseconds) so you should use the 32-bit (lower half
   * only) version when possible.
   *
   * Returns the number of cycles in the global counter.
   */
  static u64 exynos4_read_count_64(void)

  {
  	unsigned int lo, hi;

  	u32 hi2 = readl_relaxed(reg_base + EXYNOS4_MCT_G_CNT_U);

  
  	do {
  		hi = hi2;

  		lo = readl_relaxed(reg_base + EXYNOS4_MCT_G_CNT_L);
  		hi2 = readl_relaxed(reg_base + EXYNOS4_MCT_G_CNT_U);

  	} while (hi != hi2);
  
  	return ((cycle_t)hi << 32) | lo;
  }

  /**
   * exynos4_read_count_32 - Read the lower 32-bits of the global counter
   *
   * This will read just the lower 32-bits of the global counter.  This is marked
   * as notrace so it can be used by the scheduler clock.
   *
   * Returns the number of cycles in the global counter (lower 32 bits).
   */
  static u32 notrace exynos4_read_count_32(void)
  {
  	return readl_relaxed(reg_base + EXYNOS4_MCT_G_CNT_L);
  }

  static cycle_t exynos4_frc_read(struct clocksource *cs)
  {

  	return exynos4_read_count_32();

  }

  static void exynos4_frc_resume(struct clocksource *cs)
  {

  	exynos4_mct_frc_start();

  }

  static struct clocksource mct_frc = {

  	.name		= "mct-frc",
  	.rating		= 400,
  	.read		= exynos4_frc_read,

  	.mask		= CLOCKSOURCE_MASK(32),

  	.flags		= CLOCK_SOURCE_IS_CONTINUOUS,

  	.resume		= exynos4_frc_resume,

  };

  static u64 notrace exynos4_read_sched_clock(void)
  {

  	return exynos4_read_count_32();

  }

  #if defined(CONFIG_ARM)

  static struct delay_timer exynos4_delay_timer;
  
  static cycles_t exynos4_read_current_timer(void)
  {

  	BUILD_BUG_ON_MSG(sizeof(cycles_t) != sizeof(u32),
  			 "cycles_t needs to move to 32-bit for ARM64 usage");
  	return exynos4_read_count_32();

  }

  #endif

  static int __init exynos4_clocksource_init(void)

  {

  	exynos4_mct_frc_start();

  #if defined(CONFIG_ARM)

  	exynos4_delay_timer.read_current_timer = &exynos4_read_current_timer;
  	exynos4_delay_timer.freq = clk_rate;
  	register_current_timer_delay(&exynos4_delay_timer);

  #endif

  	if (clocksource_register_hz(&mct_frc, clk_rate))
  		panic("%s: can't register clocksource
  ", mct_frc.name);

  	sched_clock_register(exynos4_read_sched_clock, 32, clk_rate);

  
  	return 0;

  }
  
  static void exynos4_mct_comp0_stop(void)
  {
  	unsigned int tcon;

  	tcon = readl_relaxed(reg_base + 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(bool periodic, unsigned long cycles)

  {
  	unsigned int tcon;
  	cycle_t comp_cycle;

  	tcon = readl_relaxed(reg_base + EXYNOS4_MCT_G_TCON);

  	if (periodic) {

  		tcon |= MCT_G_TCON_COMP0_AUTO_INC;
  		exynos4_mct_write(cycles, EXYNOS4_MCT_G_COMP0_ADD_INCR);
  	}

  	comp_cycle = exynos4_read_count_64() + 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(false, cycles);

  
  	return 0;
  }

  static int mct_set_state_shutdown(struct clock_event_device *evt)

  {
  	exynos4_mct_comp0_stop();

  	return 0;
  }

  static int mct_set_state_periodic(struct clock_event_device *evt)
  {
  	unsigned long cycles_per_jiffy;
  
  	cycles_per_jiffy = (((unsigned long long)NSEC_PER_SEC / HZ * evt->mult)
  			    >> evt->shift);
  	exynos4_mct_comp0_stop();
  	exynos4_mct_comp0_start(true, cycles_per_jiffy);
  	return 0;

  }
  
  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_state_periodic	= mct_set_state_periodic,
  	.set_state_shutdown	= mct_set_state_shutdown,
  	.set_state_oneshot	= mct_set_state_shutdown,

  	.set_state_oneshot_stopped = mct_set_state_shutdown,

  	.tick_resume		= mct_set_state_shutdown,

  };
  
  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 int exynos4_clockevent_init(void)

  {

  	mct_comp_device.cpumask = cpumask_of(0);

  	clockevents_config_and_register(&mct_comp_device, clk_rate,
  					0xf, 0xffffffff);

  	setup_irq(mct_irqs[MCT_G0_IRQ], &mct_comp_event_irq);

  
  	return 0;

  }

  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;

  	unsigned long offset = mevt->base + MCT_L_TCON_OFFSET;

  	tmp = readl_relaxed(reg_base + offset);

  	if (tmp & mask) {
  		tmp &= ~mask;

  		exynos4_mct_write(tmp, offset);

  	}
  }
  
  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 = readl_relaxed(reg_base + 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;

  	mevt = container_of(evt, struct mct_clock_event_device, evt);

  	exynos4_mct_tick_start(cycles, mevt);

  	return 0;
  }

  static int set_state_shutdown(struct clock_event_device *evt)
  {

  	struct mct_clock_event_device *mevt;
  
  	mevt = container_of(evt, struct mct_clock_event_device, evt);
  	exynos4_mct_tick_stop(mevt);

  	return 0;
  }
  
  static int set_state_periodic(struct clock_event_device *evt)

  {

  	struct mct_clock_event_device *mevt;

  	unsigned long cycles_per_jiffy;

  	mevt = container_of(evt, struct mct_clock_event_device, evt);

  	cycles_per_jiffy = (((unsigned long long)NSEC_PER_SEC / HZ * evt->mult)
  			    >> evt->shift);

  	exynos4_mct_tick_stop(mevt);

  	exynos4_mct_tick_start(cycles_per_jiffy, mevt);
  	return 0;

  }

  static void exynos4_mct_tick_clear(struct mct_clock_event_device *mevt)

  {

  	/*
  	 * This is for supporting oneshot mode.
  	 * Mct would generate interrupt periodically
  	 * without explicit stopping.
  	 */

  	if (!clockevent_state_periodic(&mevt->evt))

  		exynos4_mct_tick_stop(mevt);
  
  	/* Clear the MCT tick interrupt */

  	if (readl_relaxed(reg_base + mevt->base + MCT_L_INT_CSTAT_OFFSET) & 1)

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

  }
  
  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 int exynos4_mct_starting_cpu(unsigned int cpu)

  {

  	struct mct_clock_event_device *mevt =
  		per_cpu_ptr(&percpu_mct_tick, cpu);

  	struct clock_event_device *evt = &mevt->evt;

  	mevt->base = EXYNOS4_MCT_L_BASE(cpu);

  	snprintf(mevt->name, sizeof(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_state_periodic = set_state_periodic;
  	evt->set_state_shutdown = set_state_shutdown;
  	evt->set_state_oneshot = set_state_shutdown;

  	evt->set_state_oneshot_stopped = set_state_shutdown;

  	evt->tick_resume = set_state_shutdown;

  	evt->features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT;
  	evt->rating = 450;

  	exynos4_mct_write(TICK_BASE_CNT, mevt->base + MCT_L_TCNTB_OFFSET);

  	if (mct_int_type == MCT_INT_SPI) {

  
  		if (evt->irq == -1)

  			return -EIO;

  
  		irq_force_affinity(evt->irq, cpumask_of(cpu));
  		enable_irq(evt->irq);

  	} else {

  		enable_percpu_irq(mct_irqs[MCT_L0_IRQ], 0);

  	}

  	clockevents_config_and_register(evt, clk_rate / (TICK_BASE_CNT + 1),
  					0xf, 0x7fffffff);

  
  	return 0;

  }

  static int exynos4_mct_dying_cpu(unsigned int cpu)

  {

  	struct mct_clock_event_device *mevt =
  		per_cpu_ptr(&percpu_mct_tick, cpu);

  	struct clock_event_device *evt = &mevt->evt;

  	evt->set_state_shutdown(evt);

  	if (mct_int_type == MCT_INT_SPI) {
  		if (evt->irq != -1)
  			disable_irq_nosync(evt->irq);

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

  	} else {

  		disable_percpu_irq(mct_irqs[MCT_L0_IRQ]);

  	}

  	return 0;

  }

  static int __init exynos4_timer_resources(struct device_node *np, void __iomem *base)

  {

  	int err, cpu;

  	struct clk *mct_clk, *tick_clk;

  	tick_clk = np ? of_clk_get_by_name(np, "fin_pll") :
  				clk_get(NULL, "fin_pll");
  	if (IS_ERR(tick_clk))
  		panic("%s: unable to determine tick clock rate
  ", __func__);
  	clk_rate = clk_get_rate(tick_clk);

  	mct_clk = np ? of_clk_get_by_name(np, "mct") : clk_get(NULL, "mct");
  	if (IS_ERR(mct_clk))
  		panic("%s: unable to retrieve mct clock instance
  ", __func__);
  	clk_prepare_enable(mct_clk);

  	reg_base = base;

  	if (!reg_base)
  		panic("%s: unable to ioremap mct address space
  ", __func__);

  	if (mct_int_type == MCT_INT_PPI) {

  		err = request_percpu_irq(mct_irqs[MCT_L0_IRQ],

  					 exynos4_mct_tick_isr, "MCT",
  					 &percpu_mct_tick);
  		WARN(err, "MCT: can't request IRQ %d (%d)
  ",

  		     mct_irqs[MCT_L0_IRQ], err);

  	} else {

  		for_each_possible_cpu(cpu) {
  			int mct_irq = mct_irqs[MCT_L0_IRQ + cpu];
  			struct mct_clock_event_device *pcpu_mevt =
  				per_cpu_ptr(&percpu_mct_tick, cpu);
  
  			pcpu_mevt->evt.irq = -1;
  
  			irq_set_status_flags(mct_irq, IRQ_NOAUTOEN);
  			if (request_irq(mct_irq,
  					exynos4_mct_tick_isr,
  					IRQF_TIMER | IRQF_NOBALANCING,
  					pcpu_mevt->name, pcpu_mevt)) {
  				pr_err("exynos-mct: cannot register IRQ (cpu%d)
  ",
  									cpu);
  
  				continue;
  			}
  			pcpu_mevt->evt.irq = mct_irq;
  		}

  	}

  	/* Install hotplug callbacks which configure the timer on this CPU */
  	err = cpuhp_setup_state(CPUHP_AP_EXYNOS4_MCT_TIMER_STARTING,
  				"AP_EXYNOS4_MCT_TIMER_STARTING",
  				exynos4_mct_starting_cpu,
  				exynos4_mct_dying_cpu);

  	if (err)
  		goto out_irq;

  	return 0;

  
  out_irq:
  	free_percpu_irq(mct_irqs[MCT_L0_IRQ], &percpu_mct_tick);

  	return err;

  }

  static int __init mct_init_dt(struct device_node *np, unsigned int int_type)

  {
  	u32 nr_irqs, i;

  	int ret;

  
  	mct_int_type = int_type;
  
  	/* This driver uses only one global timer interrupt */
  	mct_irqs[MCT_G0_IRQ] = irq_of_parse_and_map(np, MCT_G0_IRQ);
  
  	/*
  	 * Find out the number of local irqs specified. The local
  	 * timer irqs are specified after the four global timer
  	 * irqs are specified.
  	 */

  #ifdef CONFIG_OF

  	nr_irqs = of_irq_count(np);

  #else
  	nr_irqs = 0;
  #endif

  	for (i = MCT_L0_IRQ; i < nr_irqs; i++)
  		mct_irqs[i] = irq_of_parse_and_map(np, i);

  	ret = exynos4_timer_resources(np, of_iomap(np, 0));
  	if (ret)
  		return ret;
  
  	ret = exynos4_clocksource_init();
  	if (ret)
  		return ret;
  
  	return exynos4_clockevent_init();

  }

  static int __init mct_init_spi(struct device_node *np)

  {
  	return mct_init_dt(np, MCT_INT_SPI);
  }

  static int __init mct_init_ppi(struct device_node *np)

  {
  	return mct_init_dt(np, MCT_INT_PPI);
  }

  CLOCKSOURCE_OF_DECLARE(exynos4210, "samsung,exynos4210-mct", mct_init_spi);
  CLOCKSOURCE_OF_DECLARE(exynos4412, "samsung,exynos4412-mct", mct_init_ppi);