/*
 * Copyright (C) 2010 Google, Inc.
 *
 * Author:
 *	Colin Cross <ccross@google.com>
 *
 * This software is licensed under the terms of the GNU General Public
 * License version 2, as published by the Free Software Foundation, and
 * may be copied, distributed, and modified under those terms.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 */

#include <linux/clk.h>
#include <linux/clockchips.h>
#include <linux/cpu.h>
#include <linux/cpumask.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/interrupt.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <linux/percpu.h>
#include <linux/sched_clock.h>
#include <linux/time.h>

#include "timer-of.h"

#ifdef CONFIG_ARM
#include <asm/mach/time.h>
#endif

#define RTC_SECONDS            0x08
#define RTC_SHADOW_SECONDS     0x0c
#define RTC_MILLISECONDS       0x10

#define TIMERUS_CNTR_1US 0x10
#define TIMERUS_USEC_CFG 0x14
#define TIMERUS_CNTR_FREEZE 0x4c

#define TIMER_PTV		0x0
#define TIMER_PTV_EN		BIT(31)
#define TIMER_PTV_PER		BIT(30)
#define TIMER_PCR		0x4
#define TIMER_PCR_INTR_CLR	BIT(30)

#ifdef CONFIG_ARM
#define TIMER_CPU0		0x50 /* TIMER3 */
#else
#define TIMER_CPU0		0x90 /* TIMER10 */
#define TIMER10_IRQ_IDX		10
#define IRQ_IDX_FOR_CPU(cpu)	(TIMER10_IRQ_IDX + cpu)
#endif
#define TIMER_BASE_FOR_CPU(cpu) (TIMER_CPU0 + (cpu) * 8)

static u32 usec_config;
static void __iomem *timer_reg_base;
#ifdef CONFIG_ARM
static void __iomem *rtc_base;
static struct timespec64 persistent_ts;
static u64 persistent_ms, last_persistent_ms;
static struct delay_timer tegra_delay_timer;
#endif

static int tegra_timer_set_next_event(unsigned long cycles,
					 struct clock_event_device *evt)
{
	void __iomem *reg_base = timer_of_base(to_timer_of(evt));

	writel(TIMER_PTV_EN |
	       ((cycles > 1) ? (cycles - 1) : 0), /* n+1 scheme */
	       reg_base + TIMER_PTV);

	return 0;
}

static int tegra_timer_shutdown(struct clock_event_device *evt)
{
	void __iomem *reg_base = timer_of_base(to_timer_of(evt));

	writel(0, reg_base + TIMER_PTV);

	return 0;
}

static int tegra_timer_set_periodic(struct clock_event_device *evt)
{
	void __iomem *reg_base = timer_of_base(to_timer_of(evt));

	writel(TIMER_PTV_EN | TIMER_PTV_PER |
	       ((timer_of_rate(to_timer_of(evt)) / HZ) - 1),
	       reg_base + TIMER_PTV);

	return 0;
}

static irqreturn_t tegra_timer_isr(int irq, void *dev_id)
{
	struct clock_event_device *evt = (struct clock_event_device *)dev_id;
	void __iomem *reg_base = timer_of_base(to_timer_of(evt));

	writel(TIMER_PCR_INTR_CLR, reg_base + TIMER_PCR);
	evt->event_handler(evt);

	return IRQ_HANDLED;
}

static void tegra_timer_suspend(struct clock_event_device *evt)
{
	void __iomem *reg_base = timer_of_base(to_timer_of(evt));

	writel(TIMER_PCR_INTR_CLR, reg_base + TIMER_PCR);
}

static void tegra_timer_resume(struct clock_event_device *evt)
{
	writel(usec_config, timer_reg_base + TIMERUS_USEC_CFG);
}

#ifdef CONFIG_ARM64
static DEFINE_PER_CPU(struct timer_of, tegra_to) = {
	.flags = TIMER_OF_CLOCK | TIMER_OF_BASE,

	.clkevt = {
		.name = "tegra_timer",
		.rating = 460,
		.features = CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_FEAT_PERIODIC,
		.set_next_event = tegra_timer_set_next_event,
		.set_state_shutdown = tegra_timer_shutdown,
		.set_state_periodic = tegra_timer_set_periodic,
		.set_state_oneshot = tegra_timer_shutdown,
		.tick_resume = tegra_timer_shutdown,
		.suspend = tegra_timer_suspend,
		.resume = tegra_timer_resume,
	},
};

static int tegra_timer_setup(unsigned int cpu)
{
	struct timer_of *to = per_cpu_ptr(&tegra_to, cpu);

	irq_force_affinity(to->clkevt.irq, cpumask_of(cpu));
	enable_irq(to->clkevt.irq);

	clockevents_config_and_register(&to->clkevt, timer_of_rate(to),
					1, /* min */
					0x1fffffff); /* 29 bits */

	return 0;
}

static int tegra_timer_stop(unsigned int cpu)
{
	struct timer_of *to = per_cpu_ptr(&tegra_to, cpu);

	to->clkevt.set_state_shutdown(&to->clkevt);
	disable_irq_nosync(to->clkevt.irq);

	return 0;
}
#else /* CONFIG_ARM */
static struct timer_of tegra_to = {
	.flags = TIMER_OF_CLOCK | TIMER_OF_BASE | TIMER_OF_IRQ,

	.clkevt = {
		.name = "tegra_timer",
		.rating	= 300,
		.features = CLOCK_EVT_FEAT_ONESHOT |
			    CLOCK_EVT_FEAT_PERIODIC |
			    CLOCK_EVT_FEAT_DYNIRQ,
		.set_next_event	= tegra_timer_set_next_event,
		.set_state_shutdown = tegra_timer_shutdown,
		.set_state_periodic = tegra_timer_set_periodic,
		.set_state_oneshot = tegra_timer_shutdown,
		.tick_resume = tegra_timer_shutdown,
		.suspend = tegra_timer_suspend,
		.resume = tegra_timer_resume,
		.cpumask = cpu_possible_mask,
	},

	.of_irq = {
		.index = 2,
		.flags = IRQF_TIMER | IRQF_TRIGGER_HIGH,
		.handler = tegra_timer_isr,
	},
};

static u64 notrace tegra_read_sched_clock(void)
{
	return readl(timer_reg_base + TIMERUS_CNTR_1US);
}

static unsigned long tegra_delay_timer_read_counter_long(void)
{
	return readl(timer_reg_base + TIMERUS_CNTR_1US);
}

/*
 * tegra_rtc_read - Reads the Tegra RTC registers
 * Care must be taken that this funciton is not called while the
 * tegra_rtc driver could be executing to avoid race conditions
 * on the RTC shadow register
 */
static u64 tegra_rtc_read_ms(void)
{
	u32 ms = readl(rtc_base + RTC_MILLISECONDS);
	u32 s = readl(rtc_base + RTC_SHADOW_SECONDS);
	return (u64)s * MSEC_PER_SEC + ms;
}

/*
 * tegra_read_persistent_clock64 -  Return time from a persistent clock.
 *
 * Reads the time from a source which isn't disabled during PM, the
 * 32k sync timer.  Convert the cycles elapsed since last read into
 * nsecs and adds to a monotonically increasing timespec64.
 * Care must be taken that this funciton is not called while the
 * tegra_rtc driver could be executing to avoid race conditions
 * on the RTC shadow register
 */
static void tegra_read_persistent_clock64(struct timespec64 *ts)
{
	u64 delta;

	last_persistent_ms = persistent_ms;
	persistent_ms = tegra_rtc_read_ms();
	delta = persistent_ms - last_persistent_ms;

	timespec64_add_ns(&persistent_ts, delta * NSEC_PER_MSEC);
	*ts = persistent_ts;
}
#endif

static int tegra_timer_common_init(struct device_node *np, struct timer_of *to)
{
	int ret = 0;

	ret = timer_of_init(np, to);
	if (ret < 0)
		goto out;

	timer_reg_base = timer_of_base(to);

	/*
	 * Configure microsecond timers to have 1MHz clock
	 * Config register is 0xqqww, where qq is "dividend", ww is "divisor"
	 * Uses n+1 scheme
	 */
	switch (timer_of_rate(to)) {
	case 12000000:
		usec_config = 0x000b; /* (11+1)/(0+1) */
		break;
	case 12800000:
		usec_config = 0x043f; /* (63+1)/(4+1) */
		break;
	case 13000000:
		usec_config = 0x000c; /* (12+1)/(0+1) */
		break;
	case 16800000:
		usec_config = 0x0453; /* (83+1)/(4+1) */
		break;
	case 19200000:
		usec_config = 0x045f; /* (95+1)/(4+1) */
		break;
	case 26000000:
		usec_config = 0x0019; /* (25+1)/(0+1) */
		break;
	case 38400000:
		usec_config = 0x04bf; /* (191+1)/(4+1) */
		break;
	case 48000000:
		usec_config = 0x002f; /* (47+1)/(0+1) */
		break;
	default:
		ret = -EINVAL;
		goto out;
	}

	writel(usec_config, timer_of_base(to) + TIMERUS_USEC_CFG);

out:
	return ret;
}

#ifdef CONFIG_ARM64
static int __init tegra_init_timer(struct device_node *np)
{
	int cpu, ret = 0;
	struct timer_of *to;

	to = this_cpu_ptr(&tegra_to);
	ret = tegra_timer_common_init(np, to);
	if (ret < 0)
		goto out;

	for_each_possible_cpu(cpu) {
		struct timer_of *cpu_to;

		cpu_to = per_cpu_ptr(&tegra_to, cpu);
		cpu_to->of_base.base = timer_reg_base + TIMER_BASE_FOR_CPU(cpu);
		cpu_to->of_clk.rate = timer_of_rate(to);
		cpu_to->clkevt.cpumask = cpumask_of(cpu);
		cpu_to->clkevt.irq =
			irq_of_parse_and_map(np, IRQ_IDX_FOR_CPU(cpu));
		if (!cpu_to->clkevt.irq) {
			pr_err("%s: can't map IRQ for CPU%d\n",
			       __func__, cpu);
			ret = -EINVAL;
			goto out;
		}

		irq_set_status_flags(cpu_to->clkevt.irq, IRQ_NOAUTOEN);
		ret = request_irq(cpu_to->clkevt.irq, tegra_timer_isr,
				  IRQF_TIMER | IRQF_NOBALANCING,
				  cpu_to->clkevt.name, &cpu_to->clkevt);
		if (ret) {
			pr_err("%s: cannot setup irq %d for CPU%d\n",
				__func__, cpu_to->clkevt.irq, cpu);
			ret = -EINVAL;
			goto out_irq;
		}
	}

	cpuhp_setup_state(CPUHP_AP_TEGRA_TIMER_STARTING,
			  "AP_TEGRA_TIMER_STARTING", tegra_timer_setup,
			  tegra_timer_stop);

	return ret;
out_irq:
	for_each_possible_cpu(cpu) {
		struct timer_of *cpu_to;

		cpu_to = per_cpu_ptr(&tegra_to, cpu);
		if (cpu_to->clkevt.irq) {
			free_irq(cpu_to->clkevt.irq, &cpu_to->clkevt);
			irq_dispose_mapping(cpu_to->clkevt.irq);
		}
	}
out:
	timer_of_cleanup(to);
	return ret;
}
#else /* CONFIG_ARM */
static int __init tegra_init_timer(struct device_node *np)
{
	int ret = 0;

	ret = tegra_timer_common_init(np, &tegra_to);
	if (ret < 0)
		goto out;

	tegra_to.of_base.base = timer_reg_base + TIMER_BASE_FOR_CPU(0);
	tegra_to.of_clk.rate = 1000000; /* microsecond timer */

	sched_clock_register(tegra_read_sched_clock, 32,
			     timer_of_rate(&tegra_to));
	ret = clocksource_mmio_init(timer_reg_base + TIMERUS_CNTR_1US,
				    "timer_us", timer_of_rate(&tegra_to),
				    300, 32, clocksource_mmio_readl_up);
	if (ret) {
		pr_err("Failed to register clocksource\n");
		goto out;
	}

	tegra_delay_timer.read_current_timer =
			tegra_delay_timer_read_counter_long;
	tegra_delay_timer.freq = timer_of_rate(&tegra_to);
	register_current_timer_delay(&tegra_delay_timer);

	clockevents_config_and_register(&tegra_to.clkevt,
					timer_of_rate(&tegra_to),
					0x1,
					0x1fffffff);

	return ret;
out:
	timer_of_cleanup(&tegra_to);

	return ret;
}

static int __init tegra20_init_rtc(struct device_node *np)
{
	struct clk *clk;

	rtc_base = of_iomap(np, 0);
	if (!rtc_base) {
		pr_err("Can't map RTC registers\n");
		return -ENXIO;
	}

	/*
	 * rtc registers are used by read_persistent_clock, keep the rtc clock
	 * enabled
	 */
	clk = of_clk_get(np, 0);
	if (IS_ERR(clk))
		pr_warn("Unable to get rtc-tegra clock\n");
	else
		clk_prepare_enable(clk);

	return register_persistent_clock(tegra_read_persistent_clock64);
}
TIMER_OF_DECLARE(tegra20_rtc, "nvidia,tegra20-rtc", tegra20_init_rtc);
#endif
TIMER_OF_DECLARE(tegra210_timer, "nvidia,tegra210-timer", tegra_init_timer);
TIMER_OF_DECLARE(tegra20_timer, "nvidia,tegra20-timer", tegra_init_timer);