/*
 * Copyright (C) 2007-2009 Michal Simek <monstr@monstr.eu>
 * Copyright (C) 2007-2009 PetaLogix
 * Copyright (C) 2006 Atmark Techno, Inc.
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License. See the file "COPYING" in the main directory of this archive
 * for more details.
 */

#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/param.h>
#include <linux/interrupt.h>
#include <linux/profile.h>
#include <linux/irq.h>
#include <linux/delay.h>
#include <linux/sched.h>
#include <linux/spinlock.h>
#include <linux/err.h>
#include <linux/clk.h>
#include <linux/clocksource.h>
#include <linux/clockchips.h>
#include <linux/io.h>
#include <linux/bug.h>
#include <asm/cpuinfo.h>
#include <asm/setup.h>
#include <asm/prom.h>
#include <asm/irq.h>
#include <asm/system.h>
#include <linux/cnt32_to_63.h>

#ifdef CONFIG_SELFMOD_TIMER
#include <asm/selfmod.h>
#define TIMER_BASE	BARRIER_BASE_ADDR
#else
static unsigned int timer_baseaddr;
#define TIMER_BASE	timer_baseaddr
#endif

static unsigned int freq_div_hz;
static unsigned int timer_clock_freq;

#define TCSR0	(0x00)
#define TLR0	(0x04)
#define TCR0	(0x08)
#define TCSR1	(0x10)
#define TLR1	(0x14)
#define TCR1	(0x18)

#define TCSR_MDT	(1<<0)
#define TCSR_UDT	(1<<1)
#define TCSR_GENT	(1<<2)
#define TCSR_CAPT	(1<<3)
#define TCSR_ARHT	(1<<4)
#define TCSR_LOAD	(1<<5)
#define TCSR_ENIT	(1<<6)
#define TCSR_ENT	(1<<7)
#define TCSR_TINT	(1<<8)
#define TCSR_PWMA	(1<<9)
#define TCSR_ENALL	(1<<10)

static inline void microblaze_timer0_stop(void)
{
	out_be32(TIMER_BASE + TCSR0, in_be32(TIMER_BASE + TCSR0) & ~TCSR_ENT);
}

static inline void microblaze_timer0_start_periodic(unsigned long load_val)
{
	if (!load_val)
		load_val = 1;
	out_be32(TIMER_BASE + TLR0, load_val); /* loading value to timer reg */

	/* load the initial value */
	out_be32(TIMER_BASE + TCSR0, TCSR_LOAD);

	/* see timer data sheet for detail
	 * !ENALL - don't enable 'em all
	 * !PWMA - disable pwm
	 * TINT - clear interrupt status
	 * ENT- enable timer itself
	 * EINT - enable interrupt
	 * !LOAD - clear the bit to let go
	 * ARHT - auto reload
	 * !CAPT - no external trigger
	 * !GENT - no external signal
	 * UDT - set the timer as down counter
	 * !MDT0 - generate mode
	 */
	out_be32(TIMER_BASE + TCSR0,
			TCSR_TINT|TCSR_ENIT|TCSR_ENT|TCSR_ARHT|TCSR_UDT);
}

static inline void microblaze_timer0_start_oneshot(unsigned long load_val)
{
	if (!load_val)
		load_val = 1;
	out_be32(TIMER_BASE + TLR0, load_val); /* loading value to timer reg */

	/* load the initial value */
	out_be32(TIMER_BASE + TCSR0, TCSR_LOAD);

	out_be32(TIMER_BASE + TCSR0,
			TCSR_TINT|TCSR_ENIT|TCSR_ENT|TCSR_ARHT|TCSR_UDT);
}

static int microblaze_timer_set_next_event(unsigned long delta,
					struct clock_event_device *dev)
{
	pr_debug("%s: next event, delta %x\n", __func__, (u32)delta);
	microblaze_timer0_start_oneshot(delta);
	return 0;
}

static void microblaze_timer_set_mode(enum clock_event_mode mode,
				struct clock_event_device *evt)
{
	switch (mode) {
	case CLOCK_EVT_MODE_PERIODIC:
		printk(KERN_INFO "%s: periodic\n", __func__);
		microblaze_timer0_start_periodic(freq_div_hz);
		break;
	case CLOCK_EVT_MODE_ONESHOT:
		printk(KERN_INFO "%s: oneshot\n", __func__);
		break;
	case CLOCK_EVT_MODE_UNUSED:
		printk(KERN_INFO "%s: unused\n", __func__);
		break;
	case CLOCK_EVT_MODE_SHUTDOWN:
		printk(KERN_INFO "%s: shutdown\n", __func__);
		microblaze_timer0_stop();
		break;
	case CLOCK_EVT_MODE_RESUME:
		printk(KERN_INFO "%s: resume\n", __func__);
		break;
	}
}

static struct clock_event_device clockevent_microblaze_timer = {
	.name		= "microblaze_clockevent",
	.features       = CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_FEAT_PERIODIC,
	.shift		= 8,
	.rating		= 300,
	.set_next_event	= microblaze_timer_set_next_event,
	.set_mode	= microblaze_timer_set_mode,
};

static inline void timer_ack(void)
{
	out_be32(TIMER_BASE + TCSR0, in_be32(TIMER_BASE + TCSR0));
}

static irqreturn_t timer_interrupt(int irq, void *dev_id)
{
	struct clock_event_device *evt = &clockevent_microblaze_timer;
#ifdef CONFIG_HEART_BEAT
	heartbeat();
#endif
	timer_ack();
	evt->event_handler(evt);
	return IRQ_HANDLED;
}

static struct irqaction timer_irqaction = {
	.handler = timer_interrupt,
	.flags = IRQF_DISABLED | IRQF_TIMER,
	.name = "timer",
	.dev_id = &clockevent_microblaze_timer,
};

static __init void microblaze_clockevent_init(void)
{
	clockevent_microblaze_timer.mult =
		div_sc(timer_clock_freq, NSEC_PER_SEC,
				clockevent_microblaze_timer.shift);
	clockevent_microblaze_timer.max_delta_ns =
		clockevent_delta2ns((u32)~0, &clockevent_microblaze_timer);
	clockevent_microblaze_timer.min_delta_ns =
		clockevent_delta2ns(1, &clockevent_microblaze_timer);
	clockevent_microblaze_timer.cpumask = cpumask_of(0);
	clockevents_register_device(&clockevent_microblaze_timer);
}

static cycle_t microblaze_read(struct clocksource *cs)
{
	/* reading actual value of timer 1 */
	return (cycle_t) (in_be32(TIMER_BASE + TCR1));
}

static struct timecounter microblaze_tc = {
	.cc = NULL,
};

static cycle_t microblaze_cc_read(const struct cyclecounter *cc)
{
	return microblaze_read(NULL);
}

static struct cyclecounter microblaze_cc = {
	.read = microblaze_cc_read,
	.mask = CLOCKSOURCE_MASK(32),
	.shift = 8,
};

static int __init init_microblaze_timecounter(void)
{
	microblaze_cc.mult = div_sc(timer_clock_freq, NSEC_PER_SEC,
				microblaze_cc.shift);

	timecounter_init(&microblaze_tc, &microblaze_cc, sched_clock());

	return 0;
}

static struct clocksource clocksource_microblaze = {
	.name		= "microblaze_clocksource",
	.rating		= 300,
	.read		= microblaze_read,
	.mask		= CLOCKSOURCE_MASK(32),
	.flags		= CLOCK_SOURCE_IS_CONTINUOUS,
};

static int __init microblaze_clocksource_init(void)
{
	if (clocksource_register_hz(&clocksource_microblaze, timer_clock_freq))
		panic("failed to register clocksource");

	/* stop timer1 */
	out_be32(TIMER_BASE + TCSR1, in_be32(TIMER_BASE + TCSR1) & ~TCSR_ENT);
	/* start timer1 - up counting without interrupt */
	out_be32(TIMER_BASE + TCSR1, TCSR_TINT|TCSR_ENT|TCSR_ARHT);

	/* register timecounter - for ftrace support */
	init_microblaze_timecounter();
	return 0;
}

/*
 * We have to protect accesses before timer initialization
 * and return 0 for sched_clock function below.
 */
static int timer_initialized;

void __init time_init(void)
{
	u32 irq;
	u32 timer_num = 1;
	struct device_node *timer = NULL;
	const void *prop;
#ifdef CONFIG_SELFMOD_TIMER
	unsigned int timer_baseaddr = 0;
	int arr_func[] = {
				(int)&microblaze_read,
				(int)&timer_interrupt,
				(int)&microblaze_clocksource_init,
				(int)&microblaze_timer_set_mode,
				(int)&microblaze_timer_set_next_event,
				0
			};
#endif
	timer = of_find_compatible_node(NULL, NULL, "xlnx,xps-timer-1.00.a");
	BUG_ON(!timer);

	timer_baseaddr = be32_to_cpup(of_get_property(timer, "reg", NULL));
	timer_baseaddr = (unsigned long) ioremap(timer_baseaddr, PAGE_SIZE);
	irq = irq_of_parse_and_map(timer, 0);
	timer_num = be32_to_cpup(of_get_property(timer,
						"xlnx,one-timer-only", NULL));
	if (timer_num) {
		printk(KERN_EMERG "Please enable two timers in HW\n");
		BUG();
	}

#ifdef CONFIG_SELFMOD_TIMER
	selfmod_function((int *) arr_func, timer_baseaddr);
#endif
	printk(KERN_INFO "XPS timer #0 at 0x%08x, irq=%d\n",
		timer_baseaddr, irq);

	/* If there is clock-frequency property than use it */
	prop = of_get_property(timer, "clock-frequency", NULL);
	if (prop)
		timer_clock_freq = be32_to_cpup(prop);
	else
		timer_clock_freq = cpuinfo.cpu_clock_freq;

	freq_div_hz = timer_clock_freq / HZ;

	setup_irq(irq, &timer_irqaction);
#ifdef CONFIG_HEART_BEAT
	setup_heartbeat();
#endif
	microblaze_clocksource_init();
	microblaze_clockevent_init();
	timer_initialized = 1;
}

unsigned long long notrace sched_clock(void)
{
	if (timer_initialized) {
		struct clocksource *cs = &clocksource_microblaze;

		cycle_t cyc = cnt32_to_63(cs->read(NULL)) & LLONG_MAX;
		return clocksource_cyc2ns(cyc, cs->mult, cs->shift);
	}
	return 0;
}
