/*
 * Copyright (c) 2011 Samsung Electronics Co., Ltd.
 *		http://www.samsung.com/
 *
 * samsung - Common hr-timer support (s3c and s5p)
 *
 * 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/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/sched_clock.h>

#include <asm/smp_twd.h>
#include <asm/mach/time.h>
#include <asm/mach/arch.h>
#include <asm/mach/map.h>

#include <mach/map.h>
#include <plat/devs.h>
#include <plat/regs-timer.h>
#include <plat/samsung-time.h>

static struct clk *tin_event;
static struct clk *tin_source;
static struct clk *tdiv_event;
static struct clk *tdiv_source;
static struct clk *timerclk;
static struct samsung_timer_source timer_source;
static unsigned long clock_count_per_tick;
static void samsung_timer_resume(void);

static void samsung_time_stop(enum samsung_timer_mode mode)
{
	unsigned long tcon;

	tcon = __raw_readl(S3C2410_TCON);

	switch (mode) {
	case SAMSUNG_PWM0:
		tcon &= ~S3C2410_TCON_T0START;
		break;

	case SAMSUNG_PWM1:
		tcon &= ~S3C2410_TCON_T1START;
		break;

	case SAMSUNG_PWM2:
		tcon &= ~S3C2410_TCON_T2START;
		break;

	case SAMSUNG_PWM3:
		tcon &= ~S3C2410_TCON_T3START;
		break;

	case SAMSUNG_PWM4:
		tcon &= ~S3C2410_TCON_T4START;
		break;

	default:
		printk(KERN_ERR "Invalid Timer %d\n", mode);
		break;
	}
	__raw_writel(tcon, S3C2410_TCON);
}

static void samsung_time_setup(enum samsung_timer_mode mode, unsigned long tcnt)
{
	unsigned long tcon;

	tcon = __raw_readl(S3C2410_TCON);

	tcnt--;

	switch (mode) {
	case SAMSUNG_PWM0:
		tcon &= ~(0x0f << 0);
		tcon |= S3C2410_TCON_T0MANUALUPD;
		break;

	case SAMSUNG_PWM1:
		tcon &= ~(0x0f << 8);
		tcon |= S3C2410_TCON_T1MANUALUPD;
		break;

	case SAMSUNG_PWM2:
		tcon &= ~(0x0f << 12);
		tcon |= S3C2410_TCON_T2MANUALUPD;
		break;

	case SAMSUNG_PWM3:
		tcon &= ~(0x0f << 16);
		tcon |= S3C2410_TCON_T3MANUALUPD;
		break;

	case SAMSUNG_PWM4:
		tcon &= ~(0x07 << 20);
		tcon |= S3C2410_TCON_T4MANUALUPD;
		break;

	default:
		printk(KERN_ERR "Invalid Timer %d\n", mode);
		break;
	}

	__raw_writel(tcnt, S3C2410_TCNTB(mode));
	__raw_writel(tcnt, S3C2410_TCMPB(mode));
	__raw_writel(tcon, S3C2410_TCON);
}

static void samsung_time_start(enum samsung_timer_mode mode, bool periodic)
{
	unsigned long tcon;

	tcon  = __raw_readl(S3C2410_TCON);

	switch (mode) {
	case SAMSUNG_PWM0:
		tcon |= S3C2410_TCON_T0START;
		tcon &= ~S3C2410_TCON_T0MANUALUPD;

		if (periodic)
			tcon |= S3C2410_TCON_T0RELOAD;
		else
			tcon &= ~S3C2410_TCON_T0RELOAD;
		break;

	case SAMSUNG_PWM1:
		tcon |= S3C2410_TCON_T1START;
		tcon &= ~S3C2410_TCON_T1MANUALUPD;

		if (periodic)
			tcon |= S3C2410_TCON_T1RELOAD;
		else
			tcon &= ~S3C2410_TCON_T1RELOAD;
		break;

	case SAMSUNG_PWM2:
		tcon |= S3C2410_TCON_T2START;
		tcon &= ~S3C2410_TCON_T2MANUALUPD;

		if (periodic)
			tcon |= S3C2410_TCON_T2RELOAD;
		else
			tcon &= ~S3C2410_TCON_T2RELOAD;
		break;

	case SAMSUNG_PWM3:
		tcon |= S3C2410_TCON_T3START;
		tcon &= ~S3C2410_TCON_T3MANUALUPD;

		if (periodic)
			tcon |= S3C2410_TCON_T3RELOAD;
		else
			tcon &= ~S3C2410_TCON_T3RELOAD;
		break;

	case SAMSUNG_PWM4:
		tcon |= S3C2410_TCON_T4START;
		tcon &= ~S3C2410_TCON_T4MANUALUPD;

		if (periodic)
			tcon |= S3C2410_TCON_T4RELOAD;
		else
			tcon &= ~S3C2410_TCON_T4RELOAD;
		break;

	default:
		printk(KERN_ERR "Invalid Timer %d\n", mode);
		break;
	}
	__raw_writel(tcon, S3C2410_TCON);
}

static int samsung_set_next_event(unsigned long cycles,
				struct clock_event_device *evt)
{
	samsung_time_setup(timer_source.event_id, cycles);
	samsung_time_start(timer_source.event_id, NON_PERIODIC);

	return 0;
}

static void samsung_set_mode(enum clock_event_mode mode,
				struct clock_event_device *evt)
{
	samsung_time_stop(timer_source.event_id);

	switch (mode) {
	case CLOCK_EVT_MODE_PERIODIC:
		samsung_time_setup(timer_source.event_id, clock_count_per_tick);
		samsung_time_start(timer_source.event_id, PERIODIC);
		break;

	case CLOCK_EVT_MODE_ONESHOT:
		break;

	case CLOCK_EVT_MODE_UNUSED:
	case CLOCK_EVT_MODE_SHUTDOWN:
		break;

	case CLOCK_EVT_MODE_RESUME:
		samsung_timer_resume();
		break;
	}
}

static void samsung_timer_resume(void)
{
	/* event timer restart */
	samsung_time_setup(timer_source.event_id, clock_count_per_tick);
	samsung_time_start(timer_source.event_id, PERIODIC);

	/* source timer restart */
	samsung_time_setup(timer_source.source_id, TCNT_MAX);
	samsung_time_start(timer_source.source_id, PERIODIC);
}

void __init samsung_set_timer_source(enum samsung_timer_mode event,
				 enum samsung_timer_mode source)
{
	s3c_device_timer[event].dev.bus = &platform_bus_type;
	s3c_device_timer[source].dev.bus = &platform_bus_type;

	timer_source.event_id = event;
	timer_source.source_id = source;
}

static struct clock_event_device time_event_device = {
	.name		= "samsung_event_timer",
	.features	= CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
	.rating		= 200,
	.set_next_event	= samsung_set_next_event,
	.set_mode	= samsung_set_mode,
};

static irqreturn_t samsung_clock_event_isr(int irq, void *dev_id)
{
	struct clock_event_device *evt = dev_id;

	evt->event_handler(evt);

	return IRQ_HANDLED;
}

static struct irqaction samsung_clock_event_irq = {
	.name		= "samsung_time_irq",
	.flags		= IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
	.handler	= samsung_clock_event_isr,
	.dev_id		= &time_event_device,
};

static void __init samsung_clockevent_init(void)
{
	unsigned long pclk;
	unsigned long clock_rate;
	unsigned int irq_number;
	struct clk *tscaler;

	pclk = clk_get_rate(timerclk);

	tscaler = clk_get_parent(tdiv_event);

	clk_set_rate(tscaler, pclk / TSCALER_DIV);
	clk_set_rate(tdiv_event, pclk / TDIV);
	clk_set_parent(tin_event, tdiv_event);

	clock_rate = clk_get_rate(tin_event);
	clock_count_per_tick = clock_rate / HZ;

	time_event_device.cpumask = cpumask_of(0);
	clockevents_config_and_register(&time_event_device, clock_rate, 1, -1);

	irq_number = timer_source.event_id + IRQ_TIMER0;
	setup_irq(irq_number, &samsung_clock_event_irq);
}

static void __iomem *samsung_timer_reg(void)
{
	unsigned long offset = 0;

	switch (timer_source.source_id) {
	case SAMSUNG_PWM0:
	case SAMSUNG_PWM1:
	case SAMSUNG_PWM2:
	case SAMSUNG_PWM3:
		offset = (timer_source.source_id * 0x0c) + 0x14;
		break;

	case SAMSUNG_PWM4:
		offset = 0x40;
		break;

	default:
		printk(KERN_ERR "Invalid Timer %d\n", timer_source.source_id);
		return NULL;
	}

	return S3C_TIMERREG(offset);
}

/*
 * Override the global weak sched_clock symbol with this
 * local implementation which uses the clocksource to get some
 * better resolution when scheduling the kernel. We accept that
 * this wraps around for now, since it is just a relative time
 * stamp. (Inspired by U300 implementation.)
 */
static u32 notrace samsung_read_sched_clock(void)
{
	void __iomem *reg = samsung_timer_reg();

	if (!reg)
		return 0;

	return ~__raw_readl(reg);
}

static void __init samsung_clocksource_init(void)
{
	unsigned long pclk;
	unsigned long clock_rate;

	pclk = clk_get_rate(timerclk);

	clk_set_rate(tdiv_source, pclk / TDIV);
	clk_set_parent(tin_source, tdiv_source);

	clock_rate = clk_get_rate(tin_source);

	samsung_time_setup(timer_source.source_id, TCNT_MAX);
	samsung_time_start(timer_source.source_id, PERIODIC);

	setup_sched_clock(samsung_read_sched_clock, TSIZE, clock_rate);

	if (clocksource_mmio_init(samsung_timer_reg(), "samsung_clocksource_timer",
			clock_rate, 250, TSIZE, clocksource_mmio_readl_down))
		panic("samsung_clocksource_timer: can't register clocksource\n");
}

static void __init samsung_timer_resources(void)
{

	unsigned long event_id = timer_source.event_id;
	unsigned long source_id = timer_source.source_id;
	char devname[15];

	timerclk = clk_get(NULL, "timers");
	if (IS_ERR(timerclk))
		panic("failed to get timers clock for timer");

	clk_enable(timerclk);

	sprintf(devname, "s3c24xx-pwm.%lu", event_id);
	s3c_device_timer[event_id].id = event_id;
	s3c_device_timer[event_id].dev.init_name = devname;

	tin_event = clk_get(&s3c_device_timer[event_id].dev, "pwm-tin");
	if (IS_ERR(tin_event))
		panic("failed to get pwm-tin clock for event timer");

	tdiv_event = clk_get(&s3c_device_timer[event_id].dev, "pwm-tdiv");
	if (IS_ERR(tdiv_event))
		panic("failed to get pwm-tdiv clock for event timer");

	clk_enable(tin_event);

	sprintf(devname, "s3c24xx-pwm.%lu", source_id);
	s3c_device_timer[source_id].id = source_id;
	s3c_device_timer[source_id].dev.init_name = devname;

	tin_source = clk_get(&s3c_device_timer[source_id].dev, "pwm-tin");
	if (IS_ERR(tin_source))
		panic("failed to get pwm-tin clock for source timer");

	tdiv_source = clk_get(&s3c_device_timer[source_id].dev, "pwm-tdiv");
	if (IS_ERR(tdiv_source))
		panic("failed to get pwm-tdiv clock for source timer");

	clk_enable(tin_source);
}

void __init samsung_timer_init(void)
{
	samsung_timer_resources();
	samsung_clockevent_init();
	samsung_clocksource_init();
}