/*
 * SuperH Timer Support - MTU2
 *
 *  Copyright (C) 2009 Magnus Damm
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License
 *
 * 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/delay.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/ioport.h>
#include <linux/irq.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/pm_domain.h>
#include <linux/pm_runtime.h>
#include <linux/sh_timer.h>
#include <linux/slab.h>
#include <linux/spinlock.h>

struct sh_mtu2_device;

struct sh_mtu2_channel {
	struct sh_mtu2_device *mtu;
	unsigned int index;

	void __iomem *base;

	struct clock_event_device ced;
};

struct sh_mtu2_device {
	struct platform_device *pdev;

	void __iomem *mapbase;
	struct clk *clk;

	raw_spinlock_t lock; /* Protect the shared registers */

	struct sh_mtu2_channel *channels;
	unsigned int num_channels;

	bool has_clockevent;
};

#define TSTR -1 /* shared register */
#define TCR  0 /* channel register */
#define TMDR 1 /* channel register */
#define TIOR 2 /* channel register */
#define TIER 3 /* channel register */
#define TSR  4 /* channel register */
#define TCNT 5 /* channel register */
#define TGR  6 /* channel register */

#define TCR_CCLR_NONE		(0 << 5)
#define TCR_CCLR_TGRA		(1 << 5)
#define TCR_CCLR_TGRB		(2 << 5)
#define TCR_CCLR_SYNC		(3 << 5)
#define TCR_CCLR_TGRC		(5 << 5)
#define TCR_CCLR_TGRD		(6 << 5)
#define TCR_CCLR_MASK		(7 << 5)
#define TCR_CKEG_RISING		(0 << 3)
#define TCR_CKEG_FALLING	(1 << 3)
#define TCR_CKEG_BOTH		(2 << 3)
#define TCR_CKEG_MASK		(3 << 3)
/* Values 4 to 7 are channel-dependent */
#define TCR_TPSC_P1		(0 << 0)
#define TCR_TPSC_P4		(1 << 0)
#define TCR_TPSC_P16		(2 << 0)
#define TCR_TPSC_P64		(3 << 0)
#define TCR_TPSC_CH0_TCLKA	(4 << 0)
#define TCR_TPSC_CH0_TCLKB	(5 << 0)
#define TCR_TPSC_CH0_TCLKC	(6 << 0)
#define TCR_TPSC_CH0_TCLKD	(7 << 0)
#define TCR_TPSC_CH1_TCLKA	(4 << 0)
#define TCR_TPSC_CH1_TCLKB	(5 << 0)
#define TCR_TPSC_CH1_P256	(6 << 0)
#define TCR_TPSC_CH1_TCNT2	(7 << 0)
#define TCR_TPSC_CH2_TCLKA	(4 << 0)
#define TCR_TPSC_CH2_TCLKB	(5 << 0)
#define TCR_TPSC_CH2_TCLKC	(6 << 0)
#define TCR_TPSC_CH2_P1024	(7 << 0)
#define TCR_TPSC_CH34_P256	(4 << 0)
#define TCR_TPSC_CH34_P1024	(5 << 0)
#define TCR_TPSC_CH34_TCLKA	(6 << 0)
#define TCR_TPSC_CH34_TCLKB	(7 << 0)
#define TCR_TPSC_MASK		(7 << 0)

#define TMDR_BFE		(1 << 6)
#define TMDR_BFB		(1 << 5)
#define TMDR_BFA		(1 << 4)
#define TMDR_MD_NORMAL		(0 << 0)
#define TMDR_MD_PWM_1		(2 << 0)
#define TMDR_MD_PWM_2		(3 << 0)
#define TMDR_MD_PHASE_1		(4 << 0)
#define TMDR_MD_PHASE_2		(5 << 0)
#define TMDR_MD_PHASE_3		(6 << 0)
#define TMDR_MD_PHASE_4		(7 << 0)
#define TMDR_MD_PWM_SYNC	(8 << 0)
#define TMDR_MD_PWM_COMP_CREST	(13 << 0)
#define TMDR_MD_PWM_COMP_TROUGH	(14 << 0)
#define TMDR_MD_PWM_COMP_BOTH	(15 << 0)
#define TMDR_MD_MASK		(15 << 0)

#define TIOC_IOCH(n)		((n) << 4)
#define TIOC_IOCL(n)		((n) << 0)
#define TIOR_OC_RETAIN		(0 << 0)
#define TIOR_OC_0_CLEAR		(1 << 0)
#define TIOR_OC_0_SET		(2 << 0)
#define TIOR_OC_0_TOGGLE	(3 << 0)
#define TIOR_OC_1_CLEAR		(5 << 0)
#define TIOR_OC_1_SET		(6 << 0)
#define TIOR_OC_1_TOGGLE	(7 << 0)
#define TIOR_IC_RISING		(8 << 0)
#define TIOR_IC_FALLING		(9 << 0)
#define TIOR_IC_BOTH		(10 << 0)
#define TIOR_IC_TCNT		(12 << 0)
#define TIOR_MASK		(15 << 0)

#define TIER_TTGE		(1 << 7)
#define TIER_TTGE2		(1 << 6)
#define TIER_TCIEU		(1 << 5)
#define TIER_TCIEV		(1 << 4)
#define TIER_TGIED		(1 << 3)
#define TIER_TGIEC		(1 << 2)
#define TIER_TGIEB		(1 << 1)
#define TIER_TGIEA		(1 << 0)

#define TSR_TCFD		(1 << 7)
#define TSR_TCFU		(1 << 5)
#define TSR_TCFV		(1 << 4)
#define TSR_TGFD		(1 << 3)
#define TSR_TGFC		(1 << 2)
#define TSR_TGFB		(1 << 1)
#define TSR_TGFA		(1 << 0)

static unsigned long mtu2_reg_offs[] = {
	[TCR] = 0,
	[TMDR] = 1,
	[TIOR] = 2,
	[TIER] = 4,
	[TSR] = 5,
	[TCNT] = 6,
	[TGR] = 8,
};

static inline unsigned long sh_mtu2_read(struct sh_mtu2_channel *ch, int reg_nr)
{
	unsigned long offs;

	if (reg_nr == TSTR)
		return ioread8(ch->mtu->mapbase + 0x280);

	offs = mtu2_reg_offs[reg_nr];

	if ((reg_nr == TCNT) || (reg_nr == TGR))
		return ioread16(ch->base + offs);
	else
		return ioread8(ch->base + offs);
}

static inline void sh_mtu2_write(struct sh_mtu2_channel *ch, int reg_nr,
				unsigned long value)
{
	unsigned long offs;

	if (reg_nr == TSTR)
		return iowrite8(value, ch->mtu->mapbase + 0x280);

	offs = mtu2_reg_offs[reg_nr];

	if ((reg_nr == TCNT) || (reg_nr == TGR))
		iowrite16(value, ch->base + offs);
	else
		iowrite8(value, ch->base + offs);
}

static void sh_mtu2_start_stop_ch(struct sh_mtu2_channel *ch, int start)
{
	unsigned long flags, value;

	/* start stop register shared by multiple timer channels */
	raw_spin_lock_irqsave(&ch->mtu->lock, flags);
	value = sh_mtu2_read(ch, TSTR);

	if (start)
		value |= 1 << ch->index;
	else
		value &= ~(1 << ch->index);

	sh_mtu2_write(ch, TSTR, value);
	raw_spin_unlock_irqrestore(&ch->mtu->lock, flags);
}

static int sh_mtu2_enable(struct sh_mtu2_channel *ch)
{
	unsigned long periodic;
	unsigned long rate;
	int ret;

	pm_runtime_get_sync(&ch->mtu->pdev->dev);
	dev_pm_syscore_device(&ch->mtu->pdev->dev, true);

	/* enable clock */
	ret = clk_enable(ch->mtu->clk);
	if (ret) {
		dev_err(&ch->mtu->pdev->dev, "ch%u: cannot enable clock\n",
			ch->index);
		return ret;
	}

	/* make sure channel is disabled */
	sh_mtu2_start_stop_ch(ch, 0);

	rate = clk_get_rate(ch->mtu->clk) / 64;
	periodic = (rate + HZ/2) / HZ;

	/*
	 * "Periodic Counter Operation"
	 * Clear on TGRA compare match, divide clock by 64.
	 */
	sh_mtu2_write(ch, TCR, TCR_CCLR_TGRA | TCR_TPSC_P64);
	sh_mtu2_write(ch, TIOR, TIOC_IOCH(TIOR_OC_0_CLEAR) |
		      TIOC_IOCL(TIOR_OC_0_CLEAR));
	sh_mtu2_write(ch, TGR, periodic);
	sh_mtu2_write(ch, TCNT, 0);
	sh_mtu2_write(ch, TMDR, TMDR_MD_NORMAL);
	sh_mtu2_write(ch, TIER, TIER_TGIEA);

	/* enable channel */
	sh_mtu2_start_stop_ch(ch, 1);

	return 0;
}

static void sh_mtu2_disable(struct sh_mtu2_channel *ch)
{
	/* disable channel */
	sh_mtu2_start_stop_ch(ch, 0);

	/* stop clock */
	clk_disable(ch->mtu->clk);

	dev_pm_syscore_device(&ch->mtu->pdev->dev, false);
	pm_runtime_put(&ch->mtu->pdev->dev);
}

static irqreturn_t sh_mtu2_interrupt(int irq, void *dev_id)
{
	struct sh_mtu2_channel *ch = dev_id;

	/* acknowledge interrupt */
	sh_mtu2_read(ch, TSR);
	sh_mtu2_write(ch, TSR, ~TSR_TGFA);

	/* notify clockevent layer */
	ch->ced.event_handler(&ch->ced);
	return IRQ_HANDLED;
}

static struct sh_mtu2_channel *ced_to_sh_mtu2(struct clock_event_device *ced)
{
	return container_of(ced, struct sh_mtu2_channel, ced);
}

static int sh_mtu2_clock_event_shutdown(struct clock_event_device *ced)
{
	struct sh_mtu2_channel *ch = ced_to_sh_mtu2(ced);

	if (clockevent_state_periodic(ced))
		sh_mtu2_disable(ch);

	return 0;
}

static int sh_mtu2_clock_event_set_periodic(struct clock_event_device *ced)
{
	struct sh_mtu2_channel *ch = ced_to_sh_mtu2(ced);

	if (clockevent_state_periodic(ced))
		sh_mtu2_disable(ch);

	dev_info(&ch->mtu->pdev->dev, "ch%u: used for periodic clock events\n",
		 ch->index);
	sh_mtu2_enable(ch);
	return 0;
}

static void sh_mtu2_clock_event_suspend(struct clock_event_device *ced)
{
	pm_genpd_syscore_poweroff(&ced_to_sh_mtu2(ced)->mtu->pdev->dev);
}

static void sh_mtu2_clock_event_resume(struct clock_event_device *ced)
{
	pm_genpd_syscore_poweron(&ced_to_sh_mtu2(ced)->mtu->pdev->dev);
}

static void sh_mtu2_register_clockevent(struct sh_mtu2_channel *ch,
					const char *name)
{
	struct clock_event_device *ced = &ch->ced;

	ced->name = name;
	ced->features = CLOCK_EVT_FEAT_PERIODIC;
	ced->rating = 200;
	ced->cpumask = cpu_possible_mask;
	ced->set_state_shutdown = sh_mtu2_clock_event_shutdown;
	ced->set_state_periodic = sh_mtu2_clock_event_set_periodic;
	ced->suspend = sh_mtu2_clock_event_suspend;
	ced->resume = sh_mtu2_clock_event_resume;

	dev_info(&ch->mtu->pdev->dev, "ch%u: used for clock events\n",
		 ch->index);
	clockevents_register_device(ced);
}

static int sh_mtu2_register(struct sh_mtu2_channel *ch, const char *name)
{
	ch->mtu->has_clockevent = true;
	sh_mtu2_register_clockevent(ch, name);

	return 0;
}

static int sh_mtu2_setup_channel(struct sh_mtu2_channel *ch, unsigned int index,
				 struct sh_mtu2_device *mtu)
{
	static const unsigned int channel_offsets[] = {
		0x300, 0x380, 0x000,
	};
	char name[6];
	int irq;
	int ret;

	ch->mtu = mtu;

	sprintf(name, "tgi%ua", index);
	irq = platform_get_irq_byname(mtu->pdev, name);
	if (irq < 0) {
		/* Skip channels with no declared interrupt. */
		return 0;
	}

	ret = request_irq(irq, sh_mtu2_interrupt,
			  IRQF_TIMER | IRQF_IRQPOLL | IRQF_NOBALANCING,
			  dev_name(&ch->mtu->pdev->dev), ch);
	if (ret) {
		dev_err(&ch->mtu->pdev->dev, "ch%u: failed to request irq %d\n",
			index, irq);
		return ret;
	}

	ch->base = mtu->mapbase + channel_offsets[index];
	ch->index = index;

	return sh_mtu2_register(ch, dev_name(&mtu->pdev->dev));
}

static int sh_mtu2_map_memory(struct sh_mtu2_device *mtu)
{
	struct resource *res;

	res = platform_get_resource(mtu->pdev, IORESOURCE_MEM, 0);
	if (!res) {
		dev_err(&mtu->pdev->dev, "failed to get I/O memory\n");
		return -ENXIO;
	}

	mtu->mapbase = ioremap_nocache(res->start, resource_size(res));
	if (mtu->mapbase == NULL)
		return -ENXIO;

	return 0;
}

static int sh_mtu2_setup(struct sh_mtu2_device *mtu,
			 struct platform_device *pdev)
{
	unsigned int i;
	int ret;

	mtu->pdev = pdev;

	raw_spin_lock_init(&mtu->lock);

	/* Get hold of clock. */
	mtu->clk = clk_get(&mtu->pdev->dev, "fck");
	if (IS_ERR(mtu->clk)) {
		dev_err(&mtu->pdev->dev, "cannot get clock\n");
		return PTR_ERR(mtu->clk);
	}

	ret = clk_prepare(mtu->clk);
	if (ret < 0)
		goto err_clk_put;

	/* Map the memory resource. */
	ret = sh_mtu2_map_memory(mtu);
	if (ret < 0) {
		dev_err(&mtu->pdev->dev, "failed to remap I/O memory\n");
		goto err_clk_unprepare;
	}

	/* Allocate and setup the channels. */
	mtu->num_channels = 3;

	mtu->channels = kzalloc(sizeof(*mtu->channels) * mtu->num_channels,
				GFP_KERNEL);
	if (mtu->channels == NULL) {
		ret = -ENOMEM;
		goto err_unmap;
	}

	for (i = 0; i < mtu->num_channels; ++i) {
		ret = sh_mtu2_setup_channel(&mtu->channels[i], i, mtu);
		if (ret < 0)
			goto err_unmap;
	}

	platform_set_drvdata(pdev, mtu);

	return 0;

err_unmap:
	kfree(mtu->channels);
	iounmap(mtu->mapbase);
err_clk_unprepare:
	clk_unprepare(mtu->clk);
err_clk_put:
	clk_put(mtu->clk);
	return ret;
}

static int sh_mtu2_probe(struct platform_device *pdev)
{
	struct sh_mtu2_device *mtu = platform_get_drvdata(pdev);
	int ret;

	if (!is_early_platform_device(pdev)) {
		pm_runtime_set_active(&pdev->dev);
		pm_runtime_enable(&pdev->dev);
	}

	if (mtu) {
		dev_info(&pdev->dev, "kept as earlytimer\n");
		goto out;
	}

	mtu = kzalloc(sizeof(*mtu), GFP_KERNEL);
	if (mtu == NULL)
		return -ENOMEM;

	ret = sh_mtu2_setup(mtu, pdev);
	if (ret) {
		kfree(mtu);
		pm_runtime_idle(&pdev->dev);
		return ret;
	}
	if (is_early_platform_device(pdev))
		return 0;

 out:
	if (mtu->has_clockevent)
		pm_runtime_irq_safe(&pdev->dev);
	else
		pm_runtime_idle(&pdev->dev);

	return 0;
}

static int sh_mtu2_remove(struct platform_device *pdev)
{
	return -EBUSY; /* cannot unregister clockevent */
}

static const struct platform_device_id sh_mtu2_id_table[] = {
	{ "sh-mtu2", 0 },
	{ },
};
MODULE_DEVICE_TABLE(platform, sh_mtu2_id_table);

static const struct of_device_id sh_mtu2_of_table[] __maybe_unused = {
	{ .compatible = "renesas,mtu2" },
	{ }
};
MODULE_DEVICE_TABLE(of, sh_mtu2_of_table);

static struct platform_driver sh_mtu2_device_driver = {
	.probe		= sh_mtu2_probe,
	.remove		= sh_mtu2_remove,
	.driver		= {
		.name	= "sh_mtu2",
		.of_match_table = of_match_ptr(sh_mtu2_of_table),
	},
	.id_table	= sh_mtu2_id_table,
};

static int __init sh_mtu2_init(void)
{
	return platform_driver_register(&sh_mtu2_device_driver);
}

static void __exit sh_mtu2_exit(void)
{
	platform_driver_unregister(&sh_mtu2_device_driver);
}

early_platform_init("earlytimer", &sh_mtu2_device_driver);
subsys_initcall(sh_mtu2_init);
module_exit(sh_mtu2_exit);

MODULE_AUTHOR("Magnus Damm");
MODULE_DESCRIPTION("SuperH MTU2 Timer Driver");
MODULE_LICENSE("GPL v2");