/* linux/arch/arm/mach-msm/timer.c
 *
 * Copyright (C) 2007 Google, Inc.
 *
 * This software is licensed under the terms of the GNU General Public
 * License version 2, as published by the Free Software Foundation, and
 * may be copied, distributed, and modified under those terms.
 *
 * 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.
 *
 */

#include <linux/init.h>
#include <linux/time.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/clk.h>
#include <linux/clockchips.h>
#include <linux/delay.h>
#include <linux/io.h>

#include <asm/mach/time.h>
#include <asm/hardware/gic.h>

#include <mach/msm_iomap.h>
#include <mach/cpu.h>

#define TIMER_MATCH_VAL         0x0000
#define TIMER_COUNT_VAL         0x0004
#define TIMER_ENABLE            0x0008
#define TIMER_ENABLE_CLR_ON_MATCH_EN    2
#define TIMER_ENABLE_EN                 1
#define TIMER_CLEAR             0x000C
#define DGT_CLK_CTL             0x0034
enum {
	DGT_CLK_CTL_DIV_1 = 0,
	DGT_CLK_CTL_DIV_2 = 1,
	DGT_CLK_CTL_DIV_3 = 2,
	DGT_CLK_CTL_DIV_4 = 3,
};
#define CSR_PROTECTION          0x0020
#define CSR_PROTECTION_EN               1

#define GPT_HZ 32768

enum timer_location {
	LOCAL_TIMER = 0,
	GLOBAL_TIMER = 1,
};

#define MSM_GLOBAL_TIMER MSM_CLOCK_DGT

/* TODO: Remove these ifdefs */
#if defined(CONFIG_ARCH_QSD8X50)
#define DGT_HZ (19200000 / 4) /* 19.2 MHz / 4 by default */
#define MSM_DGT_SHIFT (0)
#elif defined(CONFIG_ARCH_MSM7X30)
#define DGT_HZ (24576000 / 4) /* 24.576 MHz (LPXO) / 4 by default */
#define MSM_DGT_SHIFT (0)
#elif defined(CONFIG_ARCH_MSM8X60) || defined(CONFIG_ARCH_MSM8960)
#define DGT_HZ (27000000 / 4) /* 27 MHz (PXO) / 4 by default */
#define MSM_DGT_SHIFT (0)
#else
#define DGT_HZ 19200000 /* 19.2 MHz or 600 KHz after shift */
#define MSM_DGT_SHIFT (5)
#endif

struct msm_clock {
	struct clock_event_device   clockevent;
	struct clocksource          clocksource;
	unsigned int		    irq;
	void __iomem                *regbase;
	uint32_t                    freq;
	uint32_t                    shift;
	void __iomem                *global_counter;
	void __iomem                *local_counter;
	union {
		struct clock_event_device		*evt;
		struct clock_event_device __percpu	**percpu_evt;
	};		
};

enum {
	MSM_CLOCK_GPT,
	MSM_CLOCK_DGT,
	NR_TIMERS,
};


static struct msm_clock msm_clocks[];

static irqreturn_t msm_timer_interrupt(int irq, void *dev_id)
{
	struct clock_event_device *evt = *(struct clock_event_device **)dev_id;
	if (evt->event_handler == NULL)
		return IRQ_HANDLED;
	evt->event_handler(evt);
	return IRQ_HANDLED;
}

static cycle_t msm_read_timer_count(struct clocksource *cs)
{
	struct msm_clock *clk = container_of(cs, struct msm_clock, clocksource);

	/*
	 * Shift timer count down by a constant due to unreliable lower bits
	 * on some targets.
	 */
	return readl(clk->global_counter) >> clk->shift;
}

static struct msm_clock *clockevent_to_clock(struct clock_event_device *evt)
{
#ifdef CONFIG_SMP
	int i;
	for (i = 0; i < NR_TIMERS; i++)
		if (evt == &(msm_clocks[i].clockevent))
			return &msm_clocks[i];
	return &msm_clocks[MSM_GLOBAL_TIMER];
#else
	return container_of(evt, struct msm_clock, clockevent);
#endif
}

static int msm_timer_set_next_event(unsigned long cycles,
				    struct clock_event_device *evt)
{
	struct msm_clock *clock = clockevent_to_clock(evt);
	uint32_t now = readl(clock->local_counter);
	uint32_t alarm = now + (cycles << clock->shift);

	writel(alarm, clock->regbase + TIMER_MATCH_VAL);
	return 0;
}

static void msm_timer_set_mode(enum clock_event_mode mode,
			      struct clock_event_device *evt)
{
	struct msm_clock *clock = clockevent_to_clock(evt);

	switch (mode) {
	case CLOCK_EVT_MODE_RESUME:
	case CLOCK_EVT_MODE_PERIODIC:
		break;
	case CLOCK_EVT_MODE_ONESHOT:
		writel(TIMER_ENABLE_EN, clock->regbase + TIMER_ENABLE);
		break;
	case CLOCK_EVT_MODE_UNUSED:
	case CLOCK_EVT_MODE_SHUTDOWN:
		writel(0, clock->regbase + TIMER_ENABLE);
		break;
	}
}

static struct msm_clock msm_clocks[] = {
	[MSM_CLOCK_GPT] = {
		.clockevent = {
			.name           = "gp_timer",
			.features       = CLOCK_EVT_FEAT_ONESHOT,
			.shift          = 32,
			.rating         = 200,
			.set_next_event = msm_timer_set_next_event,
			.set_mode       = msm_timer_set_mode,
		},
		.clocksource = {
			.name           = "gp_timer",
			.rating         = 200,
			.read           = msm_read_timer_count,
			.mask           = CLOCKSOURCE_MASK(32),
			.flags          = CLOCK_SOURCE_IS_CONTINUOUS,
		},
		.irq = INT_GP_TIMER_EXP,
		.freq = GPT_HZ,
	},
	[MSM_CLOCK_DGT] = {
		.clockevent = {
			.name           = "dg_timer",
			.features       = CLOCK_EVT_FEAT_ONESHOT,
			.shift          = 32 + MSM_DGT_SHIFT,
			.rating         = 300,
			.set_next_event = msm_timer_set_next_event,
			.set_mode       = msm_timer_set_mode,
		},
		.clocksource = {
			.name           = "dg_timer",
			.rating         = 300,
			.read           = msm_read_timer_count,
			.mask           = CLOCKSOURCE_MASK((32 - MSM_DGT_SHIFT)),
			.flags          = CLOCK_SOURCE_IS_CONTINUOUS,
		},
		.irq = INT_DEBUG_TIMER_EXP,
		.freq = DGT_HZ >> MSM_DGT_SHIFT,
		.shift = MSM_DGT_SHIFT,
	}
};

static void __init msm_timer_init(void)
{
	int i;
	int res;
	int global_offset = 0;

	if (cpu_is_msm7x01()) {
		msm_clocks[MSM_CLOCK_GPT].regbase = MSM_CSR_BASE;
		msm_clocks[MSM_CLOCK_DGT].regbase = MSM_CSR_BASE + 0x10;
	} else if (cpu_is_msm7x30()) {
		msm_clocks[MSM_CLOCK_GPT].regbase = MSM_CSR_BASE + 0x04;
		msm_clocks[MSM_CLOCK_DGT].regbase = MSM_CSR_BASE + 0x24;
	} else if (cpu_is_qsd8x50()) {
		msm_clocks[MSM_CLOCK_GPT].regbase = MSM_CSR_BASE;
		msm_clocks[MSM_CLOCK_DGT].regbase = MSM_CSR_BASE + 0x10;
	} else if (cpu_is_msm8x60() || cpu_is_msm8960()) {
		msm_clocks[MSM_CLOCK_GPT].regbase = MSM_TMR_BASE + 0x04;
		msm_clocks[MSM_CLOCK_DGT].regbase = MSM_TMR_BASE + 0x24;

		/* Use CPU0's timer as the global timer. */
		global_offset = MSM_TMR0_BASE - MSM_TMR_BASE;
	} else
		BUG();

#ifdef CONFIG_ARCH_MSM_SCORPIONMP
	writel(DGT_CLK_CTL_DIV_4, MSM_TMR_BASE + DGT_CLK_CTL);
#endif

	for (i = 0; i < ARRAY_SIZE(msm_clocks); i++) {
		struct msm_clock *clock = &msm_clocks[i];
		struct clock_event_device *ce = &clock->clockevent;
		struct clocksource *cs = &clock->clocksource;

		clock->local_counter = clock->regbase + TIMER_COUNT_VAL;
		clock->global_counter = clock->local_counter + global_offset;

		writel(0, clock->regbase + TIMER_ENABLE);
		writel(0, clock->regbase + TIMER_CLEAR);
		writel(~0, clock->regbase + TIMER_MATCH_VAL);

		ce->mult = div_sc(clock->freq, NSEC_PER_SEC, ce->shift);
		/* allow at least 10 seconds to notice that the timer wrapped */
		ce->max_delta_ns =
			clockevent_delta2ns(0xf0000000 >> clock->shift, ce);
		/* 4 gets rounded down to 3 */
		ce->min_delta_ns = clockevent_delta2ns(4, ce);
		ce->cpumask = cpumask_of(0);

		res = clocksource_register_hz(cs, clock->freq);
		if (res)
			printk(KERN_ERR "msm_timer_init: clocksource_register "
			       "failed for %s\n", cs->name);

		ce->irq = clock->irq;
		if (cpu_is_msm8x60() || cpu_is_msm8960()) {
			clock->percpu_evt = alloc_percpu(struct clock_event_device *);
			if (!clock->percpu_evt) {
				pr_err("msm_timer_init: memory allocation "
				       "failed for %s\n", ce->name);
				continue;
			}

			*__this_cpu_ptr(clock->percpu_evt) = ce;
			res = request_percpu_irq(ce->irq, msm_timer_interrupt,
						 ce->name, clock->percpu_evt);
			if (!res)
				enable_percpu_irq(ce->irq, 0);
		} else {
			clock->evt = ce;
			res = request_irq(ce->irq, msm_timer_interrupt,
					  IRQF_TIMER | IRQF_NOBALANCING | IRQF_TRIGGER_RISING,
					  ce->name, &clock->evt);
		}

		if (res)
			pr_err("msm_timer_init: request_irq failed for %s\n",
			       ce->name);

		clockevents_register_device(ce);
	}
}

#ifdef CONFIG_SMP
int __cpuinit local_timer_setup(struct clock_event_device *evt)
{
	static bool local_timer_inited;
	struct msm_clock *clock = &msm_clocks[MSM_GLOBAL_TIMER];

	/* Use existing clock_event for cpu 0 */
	if (!smp_processor_id())
		return 0;

	writel(DGT_CLK_CTL_DIV_4, MSM_TMR_BASE + DGT_CLK_CTL);

	if (!local_timer_inited) {
		writel(0, clock->regbase  + TIMER_ENABLE);
		writel(0, clock->regbase + TIMER_CLEAR);
		writel(~0, clock->regbase + TIMER_MATCH_VAL);
		local_timer_inited = true;
	}
	evt->irq = clock->irq;
	evt->name = "local_timer";
	evt->features = CLOCK_EVT_FEAT_ONESHOT;
	evt->rating = clock->clockevent.rating;
	evt->set_mode = msm_timer_set_mode;
	evt->set_next_event = msm_timer_set_next_event;
	evt->shift = clock->clockevent.shift;
	evt->mult = div_sc(clock->freq, NSEC_PER_SEC, evt->shift);
	evt->max_delta_ns =
		clockevent_delta2ns(0xf0000000 >> clock->shift, evt);
	evt->min_delta_ns = clockevent_delta2ns(4, evt);

	*__this_cpu_ptr(clock->percpu_evt) = evt;
	enable_percpu_irq(evt->irq, 0);

	clockevents_register_device(evt);
	return 0;
}

void local_timer_stop(struct clock_event_device *evt)
{
	evt->set_mode(CLOCK_EVT_MODE_UNUSED, evt);
	disable_percpu_irq(evt->irq);
}

#endif

struct sys_timer msm_timer = {
	.init = msm_timer_init
};