/*
 * R-Car SYSC Power management support
 *
 * Copyright (C) 2014  Magnus Damm
 *
 * 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/delay.h>
#include <linux/err.h>
#include <linux/mm.h>
#include <linux/spinlock.h>
#include <linux/io.h>
#include "pm-rcar.h"

/* SYSC Common */
#define SYSCSR			0x00	/* SYSC Status Register */
#define SYSCISR			0x04	/* Interrupt Status Register */
#define SYSCISCR		0x08	/* Interrupt Status Clear Register */
#define SYSCIER			0x0c	/* Interrupt Enable Register */
#define SYSCIMR			0x10	/* Interrupt Mask Register */

/* SYSC Status Register */
#define SYSCSR_PONENB		1	/* Ready for power resume requests */
#define SYSCSR_POFFENB		0	/* Ready for power shutoff requests */

/*
 * Power Control Register Offsets inside the register block for each domain
 * Note: The "CR" registers for ARM cores exist on H1 only
 *       Use WFI to power off, CPG/APMU to resume ARM cores on R-Car Gen2
 */
#define PWRSR_OFFS		0x00	/* Power Status Register */
#define PWROFFCR_OFFS		0x04	/* Power Shutoff Control Register */
#define PWROFFSR_OFFS		0x08	/* Power Shutoff Status Register */
#define PWRONCR_OFFS		0x0c	/* Power Resume Control Register */
#define PWRONSR_OFFS		0x10	/* Power Resume Status Register */
#define PWRER_OFFS		0x14	/* Power Shutoff/Resume Error */


#define SYSCSR_RETRIES		100
#define SYSCSR_DELAY_US		1

#define PWRER_RETRIES		100
#define PWRER_DELAY_US		1

#define SYSCISR_RETRIES		1000
#define SYSCISR_DELAY_US	1

static void __iomem *rcar_sysc_base;
static DEFINE_SPINLOCK(rcar_sysc_lock); /* SMP CPUs + I/O devices */

static int rcar_sysc_pwr_on_off(const struct rcar_sysc_ch *sysc_ch, bool on)
{
	unsigned int sr_bit, reg_offs;
	int k;

	if (on) {
		sr_bit = SYSCSR_PONENB;
		reg_offs = PWRONCR_OFFS;
	} else {
		sr_bit = SYSCSR_POFFENB;
		reg_offs = PWROFFCR_OFFS;
	}

	/* Wait until SYSC is ready to accept a power request */
	for (k = 0; k < SYSCSR_RETRIES; k++) {
		if (ioread32(rcar_sysc_base + SYSCSR) & BIT(sr_bit))
			break;
		udelay(SYSCSR_DELAY_US);
	}

	if (k == SYSCSR_RETRIES)
		return -EAGAIN;

	/* Submit power shutoff or power resume request */
	iowrite32(BIT(sysc_ch->chan_bit),
		  rcar_sysc_base + sysc_ch->chan_offs + reg_offs);

	return 0;
}

static int rcar_sysc_power(const struct rcar_sysc_ch *sysc_ch, bool on)
{
	unsigned int isr_mask = BIT(sysc_ch->isr_bit);
	unsigned int chan_mask = BIT(sysc_ch->chan_bit);
	unsigned int status;
	unsigned long flags;
	int ret = 0;
	int k;

	spin_lock_irqsave(&rcar_sysc_lock, flags);

	iowrite32(isr_mask, rcar_sysc_base + SYSCISCR);

	/* Submit power shutoff or resume request until it was accepted */
	for (k = 0; k < PWRER_RETRIES; k++) {
		ret = rcar_sysc_pwr_on_off(sysc_ch, on);
		if (ret)
			goto out;

		status = ioread32(rcar_sysc_base +
				  sysc_ch->chan_offs + PWRER_OFFS);
		if (!(status & chan_mask))
			break;

		udelay(PWRER_DELAY_US);
	}

	if (k == PWRER_RETRIES) {
		ret = -EIO;
		goto out;
	}

	/* Wait until the power shutoff or resume request has completed * */
	for (k = 0; k < SYSCISR_RETRIES; k++) {
		if (ioread32(rcar_sysc_base + SYSCISR) & isr_mask)
			break;
		udelay(SYSCISR_DELAY_US);
	}

	if (k == SYSCISR_RETRIES)
		ret = -EIO;

	iowrite32(isr_mask, rcar_sysc_base + SYSCISCR);

 out:
	spin_unlock_irqrestore(&rcar_sysc_lock, flags);

	pr_debug("sysc power domain %d: %08x -> %d\n",
		 sysc_ch->isr_bit, ioread32(rcar_sysc_base + SYSCISR), ret);
	return ret;
}

int rcar_sysc_power_down(const struct rcar_sysc_ch *sysc_ch)
{
	return rcar_sysc_power(sysc_ch, false);
}

int rcar_sysc_power_up(const struct rcar_sysc_ch *sysc_ch)
{
	return rcar_sysc_power(sysc_ch, true);
}

bool rcar_sysc_power_is_off(const struct rcar_sysc_ch *sysc_ch)
{
	unsigned int st;

	st = ioread32(rcar_sysc_base + sysc_ch->chan_offs + PWRSR_OFFS);
	if (st & BIT(sysc_ch->chan_bit))
		return true;

	return false;
}

void __iomem *rcar_sysc_init(phys_addr_t base)
{
	rcar_sysc_base = ioremap_nocache(base, PAGE_SIZE);
	if (!rcar_sysc_base)
		panic("unable to ioremap R-Car SYSC hardware block\n");

	return rcar_sysc_base;
}