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// SPDX-License-Identifier: GPL-2.0
// Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.

#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/sched_clock.h>
#include <linux/cpu.h>
#include <linux/of_irq.h>
#include <asm/reg_ops.h>

#include "timer-of.h"

#define PTIM_CCVR	"cr<3, 14>"
#define PTIM_CTLR	"cr<0, 14>"
#define PTIM_LVR	"cr<6, 14>"
#define PTIM_TSR	"cr<1, 14>"

static int csky_mptimer_irq;

static int csky_mptimer_set_next_event(unsigned long delta,
				       struct clock_event_device *ce)
{
	mtcr(PTIM_LVR, delta);

	return 0;
}

static int csky_mptimer_shutdown(struct clock_event_device *ce)
{
	mtcr(PTIM_CTLR, 0);

	return 0;
}

static int csky_mptimer_oneshot(struct clock_event_device *ce)
{
	mtcr(PTIM_CTLR, 1);

	return 0;
}

static int csky_mptimer_oneshot_stopped(struct clock_event_device *ce)
{
	mtcr(PTIM_CTLR, 0);

	return 0;
}

static DEFINE_PER_CPU(struct timer_of, csky_to) = {
	.flags					= TIMER_OF_CLOCK,
	.clkevt = {
		.rating				= 300,
		.features			= CLOCK_EVT_FEAT_PERCPU |
						  CLOCK_EVT_FEAT_ONESHOT,
		.set_state_shutdown		= csky_mptimer_shutdown,
		.set_state_oneshot		= csky_mptimer_oneshot,
		.set_state_oneshot_stopped	= csky_mptimer_oneshot_stopped,
		.set_next_event			= csky_mptimer_set_next_event,
	},
};

static irqreturn_t csky_timer_interrupt(int irq, void *dev)
{
	struct timer_of *to = this_cpu_ptr(&csky_to);

	mtcr(PTIM_TSR, 0);

	to->clkevt.event_handler(&to->clkevt);

	return IRQ_HANDLED;
}

/*
 * clock event for percpu
 */
static int csky_mptimer_starting_cpu(unsigned int cpu)
{
	struct timer_of *to = per_cpu_ptr(&csky_to, cpu);

	to->clkevt.cpumask = cpumask_of(cpu);

	clockevents_config_and_register(&to->clkevt, timer_of_rate(to),
					2, ULONG_MAX);

	enable_percpu_irq(csky_mptimer_irq, 0);

	return 0;
}

static int csky_mptimer_dying_cpu(unsigned int cpu)
{
	disable_percpu_irq(csky_mptimer_irq);

	return 0;
}

/*
 * clock source
 */
static u64 sched_clock_read(void)
{
	return (u64)mfcr(PTIM_CCVR);
}

static u64 clksrc_read(struct clocksource *c)
{
	return (u64)mfcr(PTIM_CCVR);
}

struct clocksource csky_clocksource = {
	.name	= "csky",
	.rating	= 400,
	.mask	= CLOCKSOURCE_MASK(32),
	.flags	= CLOCK_SOURCE_IS_CONTINUOUS,
	.read	= clksrc_read,
};

static int __init csky_mptimer_init(struct device_node *np)
{
	int ret, cpu, cpu_rollback;
	struct timer_of *to = NULL;

	/*
	 * Csky_mptimer is designed for C-SKY SMP multi-processors and
	 * every core has it's own private irq and regs for clkevt and
	 * clksrc.
	 *
	 * The regs is accessed by cpu instruction: mfcr/mtcr instead of
	 * mmio map style. So we needn't mmio-address in dts, but we still
	 * need to give clk and irq number.
	 *
	 * We use private irq for the mptimer and irq number is the same
	 * for every core. So we use request_percpu_irq() in timer_of_init.
	 */
	csky_mptimer_irq = irq_of_parse_and_map(np, 0);
	if (csky_mptimer_irq <= 0)
		return -EINVAL;

	ret = request_percpu_irq(csky_mptimer_irq, csky_timer_interrupt,
				 "csky_mp_timer", &csky_to);
	if (ret)
		return -EINVAL;

	for_each_possible_cpu(cpu) {
		to = per_cpu_ptr(&csky_to, cpu);
		ret = timer_of_init(np, to);
		if (ret)
			goto rollback;
	}

	clocksource_register_hz(&csky_clocksource, timer_of_rate(to));
	sched_clock_register(sched_clock_read, 32, timer_of_rate(to));

	ret = cpuhp_setup_state(CPUHP_AP_CSKY_TIMER_STARTING,
				"clockevents/csky/timer:starting",
				csky_mptimer_starting_cpu,
				csky_mptimer_dying_cpu);
	if (ret)
		return -EINVAL;

	return 0;

rollback:
	for_each_possible_cpu(cpu_rollback) {
		if (cpu_rollback == cpu)
			break;

		to = per_cpu_ptr(&csky_to, cpu_rollback);
		timer_of_cleanup(to);
	}
	return -EINVAL;
}
TIMER_OF_DECLARE(csky_mptimer, "csky,mptimer", csky_mptimer_init);