// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright 2021 StarFive, Inc <samin.guo@starfivetech.com>
 *
 * THE PRESENT SOFTWARE WHICH IS FOR GUIDANCE ONLY AIMS AT PROVIDING
 * CUSTOMERS WITH CODING INFORMATION REGARDING THEIR PRODUCTS IN ORDER
 * FOR THEM TO SAVE TIME. AS A RESULT, STARFIVE SHALL NOT BE HELD LIABLE
 * FOR ANY DIRECT, INDIRECT OR CONSEQUENTIAL DAMAGES WITH RESPECT TO ANY
 * CLAIMS ARISING FROM THE CONTENT OF SUCH SOFTWARE AND/OR THE USE MADE
 * BY CUSTOMERS OF THE CODING INFORMATION CONTAINED HEREIN IN CONNECTION
 * WITH THEIR PRODUCTS.
 */

#include <linux/clk.h>
#include <linux/clocksource.h>
#include <linux/clockchips.h>
#include <linux/err.h>
#include <linux/kernel.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/io.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_clk.h>
#include <linux/of_irq.h>
#include <linux/sched_clock.h>

#include "timer-starfive.h"

struct starfive_timer __initdata jh7100_starfive_timer = {
	.ctrl		= STF_TIMER_CTL,
	.load		= STF_TIMER_LOAD,
	.enable		= STF_TIMER_ENABLE,
	.reload		= STF_TIMER_RELOAD,
	.value		= STF_TIMER_VALUE,
	.intclr		= STF_TIMER_INT_CLR,
	.intmask	= STF_TIMER_INT_MASK,
	.timer_base	= {TIMER_BASE(0), TIMER_BASE(1), TIMER_BASE(2), TIMER_BASE(3),
			TIMER_BASE(4), TIMER_BASE(5), TIMER_BASE(6), TIMER_BASE(7)},
};

static struct starfive_clkevt starfive_jh7100_clkevt[NR_TIMERS];

static inline struct starfive_clkevt *
to_starfive_clkevt(struct clock_event_device *evt)
{
	return container_of(evt, struct starfive_clkevt, evt);
}

static inline void timer_set_mod(struct starfive_clkevt *clkevt, int mod)
{
	writel(mod, clkevt->ctrl);
}

/*
 * After disable timer, then enable, the timer will start
 * from the reload count value(0x08[31:0]).
 */
static inline void timer_int_enable(struct starfive_clkevt *clkevt)
{
	writel(INTMASK_ENABLE_DIS, clkevt->intmask);
}

static inline void timer_int_disable(struct starfive_clkevt *clkevt)
{
	writel(INTMASK_ENABLE, clkevt->intmask);
}

static inline void timer_int_clear(struct starfive_clkevt *clkevt)
{
	/* waiting interrupt can be to clearing */
	do {

	} while (readl(clkevt->intclr) & INT_STATUS_CLR_AVA);

	writel(1, clkevt->intclr);
}

/*
 * The initial value to be loaded into the
 * counter and is also used as the reload value.
 */
static inline void timer_set_val(struct starfive_clkevt *clkevt, u32 val)
{
	writel(val, clkevt->load);
}

static inline u32 timer_get_val(struct starfive_clkevt *clkevt)
{
	return readl(clkevt->value);
}

/*
 * Write RELOAD register to reload preset value to counter.
 * (Write 0 and write 1 are both ok)
 */
static inline void
timer_set_reload(struct starfive_clkevt *clkevt)
{
	writel(1, clkevt->reload);
}

static inline void timer_enable(struct starfive_clkevt *clkevt)
{
	writel(TIMER_ENA, clkevt->enable);
}

static inline void timer_disable(struct starfive_clkevt *clkevt)
{
	writel(TIMER_ENA_DIS, clkevt->enable);
}

static void timer_shutdown(struct starfive_clkevt *clkevt)
{
	timer_int_disable(clkevt);
	timer_disable(clkevt);
	timer_int_clear(clkevt);
}

static void starfive_timer_suspend(struct clock_event_device *evt)
{
	struct starfive_clkevt *clkevt;

	clkevt = to_starfive_clkevt(evt);

	clkevt->reload_val = timer_get_val(clkevt);

	timer_disable(clkevt);
	timer_int_disable(clkevt);
	timer_int_clear(clkevt);
}

static void starfive_timer_resume(struct clock_event_device *evt)
{
	struct starfive_clkevt *clkevt;

	clkevt = to_starfive_clkevt(evt);
	timer_set_val(clkevt, clkevt->reload_val);
	timer_set_reload(clkevt);
	timer_int_enable(clkevt);
	timer_enable(clkevt);
}

static int starfive_timer_tick_resume(struct clock_event_device *evt)
{
	starfive_timer_resume(evt);

	return 0;
}

static int starfive_timer_shutdown(struct clock_event_device *evt)
{
	struct starfive_clkevt *clkevt;

	clkevt = to_starfive_clkevt(evt);
	timer_shutdown(clkevt);

	return 0;
}

static int
starfive_get_clock_rate( struct starfive_clkevt *clkevt, struct device_node *np)
{
	int ret;
	u32 rate;

	if (clkevt->clk) {
		clkevt->rate = clk_get_rate(clkevt->clk);
		if (clkevt->rate > 0){
			pr_debug("clk_get_rate clkevt->rate: %lld\n", clkevt->rate);
			return 0;
		}
	}

	/* Next we try to get clock-frequency from dts.*/
	ret = of_property_read_u32(np, "clock-frequency", &rate);
	if (!ret) {
		pr_debug("Timer: try get clock-frequency:%d MHz\n", rate);
		clkevt->rate = (u64)rate;
		return 0;
	}
	else
		pr_err("Timer: get rate failed, need clock-frequency define in dts.\n");

	return -ENOENT;
}

static int starfive_clocksource_init(struct starfive_clkevt *clkevt,
				const char *name, struct device_node *np)
{
	timer_set_mod(clkevt, MOD_CONTIN);
	timer_set_val(clkevt, 0xffffffff);  /* val = rate --> 1s */
	timer_int_disable(clkevt);
	timer_int_clear(clkevt);
	timer_int_enable(clkevt);
	timer_enable(clkevt);

	clocksource_mmio_init(clkevt->value, name,
		clkevt->rate, 200, 32, clocksource_mmio_readl_down);

	return 0;
}

/*
 * IRQ handler for the timer
 */
static irqreturn_t starfive_timer_interrupt(int irq, void *priv)
{
	struct clock_event_device *evt = (struct clock_event_device  *)priv;
	struct starfive_clkevt *clkevt = to_starfive_clkevt(evt);

	timer_int_clear(clkevt);

	if (evt->event_handler)
		evt->event_handler(evt);

	return IRQ_HANDLED;
}

static int starfive_timer_set_periodic(struct clock_event_device *evt)
{
	struct starfive_clkevt *clkevt;

	clkevt = to_starfive_clkevt(evt);

	timer_disable(clkevt);
	timer_set_mod(clkevt, MOD_CONTIN);
	timer_set_val(clkevt, clkevt->periodic);
	timer_int_disable(clkevt);
	timer_int_clear(clkevt);
	timer_int_enable(clkevt);
	timer_enable(clkevt);

	return 0;
}

static int starfive_timer_set_oneshot(struct clock_event_device *evt)
{
	struct starfive_clkevt *clkevt;

	clkevt = to_starfive_clkevt(evt);

	timer_disable(clkevt);
	timer_set_mod(clkevt, MOD_SINGLE);
	timer_set_val(clkevt, 0xffffffff);
	timer_int_disable(clkevt);
	timer_int_clear(clkevt);
	timer_int_enable(clkevt);
	timer_enable(clkevt);

	return 0;
}

static int starfive_timer_set_next_event(unsigned long next,
					struct clock_event_device *evt)
{
	struct starfive_clkevt *clkevt;

	clkevt = to_starfive_clkevt(evt);

	timer_disable(clkevt);
	timer_set_mod(clkevt, MOD_SINGLE);
	timer_set_val(clkevt, next);
	timer_enable(clkevt);

	return 0;
}

static void starfive_set_clockevent(struct clock_event_device *evt)
{
	evt->features	= CLOCK_EVT_FEAT_PERIODIC |
			CLOCK_EVT_FEAT_ONESHOT |
			CLOCK_EVT_FEAT_DYNIRQ;
	evt->set_state_shutdown	= starfive_timer_shutdown;
	evt->set_state_periodic	= starfive_timer_set_periodic;
	evt->set_state_oneshot	= starfive_timer_set_oneshot;
	evt->set_state_oneshot_stopped = starfive_timer_shutdown;
	evt->tick_resume	= starfive_timer_tick_resume;
	evt->set_next_event	= starfive_timer_set_next_event;
	evt->suspend		= starfive_timer_suspend;
	evt->resume		= starfive_timer_resume;
	evt->rating		= 300;
}

static int starfive_clockevents_register(struct starfive_clkevt *clkevt, unsigned int irq,
				struct device_node *np, const char *name)
{
	int ret = 0;

	ret = starfive_get_clock_rate(clkevt, np);
	if (ret)
		return -EINVAL;

	clkevt->periodic = DIV_ROUND_CLOSEST(clkevt->rate, HZ);

	starfive_set_clockevent(&clkevt->evt);
	clkevt->evt.name = name;
	clkevt->evt.irq = irq;
	clkevt->evt.cpumask = cpu_possible_mask;

	ret = request_irq(irq, starfive_timer_interrupt,
			IRQF_TIMER | IRQF_IRQPOLL, name, &clkevt->evt);
	if (ret)
		pr_err("%s: request_irq failed\n", name);

	clockevents_config_and_register(&clkevt->evt, clkevt->rate, 0xf, 0xffffffff);

	return ret;
}

static void __init starfive_clkevt_init(struct starfive_timer *timer,
					void __iomem *base)
{
	struct starfive_clkevt *clkevt;
	void __iomem *timer_base;
	int i;

	for (i = 0; i < NR_TIMERS; i++) {
		timer_base = base + timer->timer_base[i];
		clkevt = &starfive_jh7100_clkevt[i];
		clkevt->base	= timer_base;
		clkevt->ctrl	= timer_base + timer->ctrl;
		clkevt->load	= timer_base + timer->load;
		clkevt->enable	= timer_base + timer->enable;
		clkevt->reload	= timer_base + timer->reload;
		clkevt->value	= timer_base + timer->value;
		clkevt->intclr	= timer_base + timer->intclr;
		clkevt->intmask	= timer_base + timer->intmask;
	}
}

static int __init do_starfive_timer_of_init(struct device_node *np,
					struct starfive_timer *timer)
{
	int index, count, irq, ret = -EINVAL;
	const char *name = NULL;
	struct clk *clk;
	struct clk *pclk;
	struct starfive_clkevt *clkevt;
	void __iomem *base;

	base = of_iomap(np, 0);
	if (!base)
		return -ENXIO;

	if (!of_device_is_available(np)) {
		ret = -EINVAL;
		goto err;
	}

	starfive_clkevt_init(timer, base);

	pclk = of_clk_get_by_name(np, "apb_clk");
	if (!IS_ERR(pclk))
		if (clk_prepare_enable(pclk))
			pr_warn("pclk for %pOFn is present, but could not be activated\n",
			np);

	count = of_irq_count(np);
	if (count > NR_TIMERS || count <= 0) {
		ret = -EINVAL;
		goto err;
	}

	for (index = 0; index < count; index++) {
		/* one of timer is wdog-timer, skip...*/
		of_property_read_string_index(np, "clock-names", index, &name);
		if (strncmp(name, "timer", strlen("timer")))
			continue;

		clkevt = &starfive_jh7100_clkevt[index];
		/* Ensure timers are disabled */
		timer_disable(clkevt);

		clk = of_clk_get_by_name(np, name);
		if (!IS_ERR(clk)) {
			clkevt->clk = clk;
			if (clk_prepare_enable(clk))
				pr_warn("clk for %pOFn is present, but could not be activated\n",
				np);

		}

		irq = irq_of_parse_and_map(np, index);
		if (irq < 0) {
			ret = -EINVAL;
			goto err;
		}

		ret = starfive_clockevents_register(clkevt, irq, np, name);
		if (ret) {
			pr_err("%s: init clockevents failed.\n", name);
			goto err;
		}

		ret = starfive_clocksource_init(clkevt, name, np);
		if (ret)
			goto err;
	}

	return 0;
err:
	iounmap(base);
	return ret;
}

static int __init starfive_timer_of_init(struct device_node *np)
{
	return do_starfive_timer_of_init(np, &jh7100_starfive_timer);
}
TIMER_OF_DECLARE(starfive_timer, "starfive,timers", starfive_timer_of_init);