/* linux/arch/arm/plat-s5p/s5p-time.c
 *
 * Copyright (c) 2011 Samsung Electronics Co., Ltd.
 *		http://www.samsung.com/
 *
 * S5P - Common hr-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 <asm/smp_twd.h>
#include <asm/mach/time.h>
#include <asm/mach/arch.h>
#include <asm/mach/map.h>
#include <asm/sched_clock.h>

#include <mach/map.h>
#include <plat/devs.h>
#include <plat/regs-timer.h>
#include <plat/s5p-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 s5p_timer_source timer_source;
static unsigned long clock_count_per_tick;
static void s5p_timer_resume(void);

static void s5p_time_stop(enum s5p_timer_mode mode)
{
	unsigned long tcon;

	tcon = __raw_readl(S3C2410_TCON);

	switch (mode) {
	case S5P_PWM0:
		tcon &= ~S3C2410_TCON_T0START;
		break;

	case S5P_PWM1:
		tcon &= ~S3C2410_TCON_T1START;
		break;

	case S5P_PWM2:
		tcon &= ~S3C2410_TCON_T2START;
		break;

	case S5P_PWM3:
		tcon &= ~S3C2410_TCON_T3START;
		break;

	case S5P_PWM4:
		tcon &= ~S3C2410_TCON_T4START;
		break;

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

static void s5p_time_setup(enum s5p_timer_mode mode, unsigned long tcnt)
{
	unsigned long tcon;

	tcon = __raw_readl(S3C2410_TCON);

	tcnt--;

	switch (mode) {
	case S5P_PWM0:
		tcon &= ~(0x0f << 0);
		tcon |= S3C2410_TCON_T0MANUALUPD;
		break;

	case S5P_PWM1:
		tcon &= ~(0x0f << 8);
		tcon |= S3C2410_TCON_T1MANUALUPD;
		break;

	case S5P_PWM2:
		tcon &= ~(0x0f << 12);
		tcon |= S3C2410_TCON_T2MANUALUPD;
		break;

	case S5P_PWM3:
		tcon &= ~(0x0f << 16);
		tcon |= S3C2410_TCON_T3MANUALUPD;
		break;

	case S5P_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 s5p_time_start(enum s5p_timer_mode mode, bool periodic)
{
	unsigned long tcon;

	tcon  = __raw_readl(S3C2410_TCON);

	switch (mode) {
	case S5P_PWM0:
		tcon |= S3C2410_TCON_T0START;
		tcon &= ~S3C2410_TCON_T0MANUALUPD;

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

	case S5P_PWM1:
		tcon |= S3C2410_TCON_T1START;
		tcon &= ~S3C2410_TCON_T1MANUALUPD;

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

	case S5P_PWM2:
		tcon |= S3C2410_TCON_T2START;
		tcon &= ~S3C2410_TCON_T2MANUALUPD;

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

	case S5P_PWM3:
		tcon |= S3C2410_TCON_T3START;
		tcon &= ~S3C2410_TCON_T3MANUALUPD;

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

	case S5P_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 s5p_set_next_event(unsigned long cycles,
				struct clock_event_device *evt)
{
	s5p_time_setup(timer_source.event_id, cycles);
	s5p_time_start(timer_source.event_id, NON_PERIODIC);

	return 0;
}

static void s5p_set_mode(enum clock_event_mode mode,
				struct clock_event_device *evt)
{
	s5p_time_stop(timer_source.event_id);

	switch (mode) {
	case CLOCK_EVT_MODE_PERIODIC:
		s5p_time_setup(timer_source.event_id, clock_count_per_tick);
		s5p_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:
		s5p_timer_resume();
		break;
	}
}

static void s5p_timer_resume(void)
{
	/* event timer restart */
	s5p_time_setup(timer_source.event_id, clock_count_per_tick);
	s5p_time_start(timer_source.event_id, PERIODIC);

	/* source timer restart */
	s5p_time_setup(timer_source.source_id, TCNT_MAX);
	s5p_time_start(timer_source.source_id, PERIODIC);
}

void __init s5p_set_timer_source(enum s5p_timer_mode event,
				 enum s5p_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		= "s5p_event_timer",
	.features	= CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
	.rating		= 200,
	.set_next_event	= s5p_set_next_event,
	.set_mode	= s5p_set_mode,
};

static irqreturn_t s5p_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 s5p_clock_event_irq = {
	.name		= "s5p_time_irq",
	.flags		= IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
	.handler	= s5p_clock_event_isr,
	.dev_id		= &time_event_device,
};

static void __init s5p_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 / 2);
	clk_set_rate(tdiv_event, pclk / 2);
	clk_set_parent(tin_event, tdiv_event);

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

	clockevents_calc_mult_shift(&time_event_device,
				    clock_rate, S5PTIMER_MIN_RANGE);
	time_event_device.max_delta_ns =
		clockevent_delta2ns(-1, &time_event_device);
	time_event_device.min_delta_ns =
		clockevent_delta2ns(1, &time_event_device);

	time_event_device.cpumask = cpumask_of(0);
	clockevents_register_device(&time_event_device);

	irq_number = timer_source.event_id + IRQ_TIMER0;
	setup_irq(irq_number, &s5p_clock_event_irq);
}

static cycle_t s5p_timer_read(struct clocksource *cs)
{
	unsigned long offset = 0;

	switch (timer_source.source_id) {
	case S5P_PWM0:
	case S5P_PWM1:
	case S5P_PWM2:
	case S5P_PWM3:
		offset = (timer_source.source_id * 0x0c) + 0x14;
		break;

	case S5P_PWM4:
		offset = 0x40;
		break;

	default:
		printk(KERN_ERR "Invalid Timer %d\n", timer_source.source_id);
		return 0;
	}

	return (cycle_t) ~__raw_readl(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 DEFINE_CLOCK_DATA(cd);

unsigned long long notrace sched_clock(void)
{
	u32 cyc;
	unsigned long offset = 0;

	switch (timer_source.source_id) {
	case S5P_PWM0:
	case S5P_PWM1:
	case S5P_PWM2:
	case S5P_PWM3:
		offset = (timer_source.source_id * 0x0c) + 0x14;
		break;

	case S5P_PWM4:
		offset = 0x40;
		break;

	default:
		printk(KERN_ERR "Invalid Timer %d\n", timer_source.source_id);
		return 0;
	}

	cyc = ~__raw_readl(S3C_TIMERREG(offset));
	return cyc_to_sched_clock(&cd, cyc, (u32)~0);
}

static void notrace s5p_update_sched_clock(void)
{
	u32 cyc;
	unsigned long offset = 0;

	switch (timer_source.source_id) {
	case S5P_PWM0:
	case S5P_PWM1:
	case S5P_PWM2:
	case S5P_PWM3:
		offset = (timer_source.source_id * 0x0c) + 0x14;
		break;

	case S5P_PWM4:
		offset = 0x40;
		break;

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

	cyc = ~__raw_readl(S3C_TIMERREG(offset));
	update_sched_clock(&cd, cyc, (u32)~0);
}

struct clocksource time_clocksource = {
	.name		= "s5p_clocksource_timer",
	.rating		= 250,
	.read		= s5p_timer_read,
	.mask		= CLOCKSOURCE_MASK(32),
	.flags		= CLOCK_SOURCE_IS_CONTINUOUS,
};

static void __init s5p_clocksource_init(void)
{
	unsigned long pclk;
	unsigned long clock_rate;

	pclk = clk_get_rate(timerclk);

	clk_set_rate(tdiv_source, pclk / 2);
	clk_set_parent(tin_source, tdiv_source);

	clock_rate = clk_get_rate(tin_source);

	init_sched_clock(&cd, s5p_update_sched_clock, 32, clock_rate);

	s5p_time_setup(timer_source.source_id, TCNT_MAX);
	s5p_time_start(timer_source.source_id, PERIODIC);

	if (clocksource_register_hz(&time_clocksource, clock_rate))
		panic("%s: can't register clocksource\n", time_clocksource.name);
}

static void __init s5p_timer_resources(void)
{

	unsigned long event_id = timer_source.event_id;
	unsigned long source_id = timer_source.source_id;

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

	clk_enable(timerclk);

	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);

	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);
}

static void __init s5p_timer_init(void)
{
	s5p_timer_resources();
	s5p_clockevent_init();
	s5p_clocksource_init();
}

struct sys_timer s5p_timer = {
	.init		= s5p_timer_init,
};