/*
 * 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 <asm/io.h>
#include "pm-rcar.h"

/* SYSC */
#define SYSCSR 0x00
#define SYSCISR 0x04
#define SYSCISCR 0x08

#define PWRSR_OFFS 0x00
#define PWROFFCR_OFFS 0x04
#define PWRONCR_OFFS 0x0c
#define PWRER_OFFS 0x14

#define SYSCSR_RETRIES 100
#define SYSCSR_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(struct rcar_sysc_ch *sysc_ch,
				int sr_bit, int reg_offs)
{
	int k;

	for (k = 0; k < SYSCSR_RETRIES; k++) {
		if (ioread32(rcar_sysc_base + SYSCSR) & (1 << sr_bit))
			break;
		udelay(SYSCSR_DELAY_US);
	}

	if (k == SYSCSR_RETRIES)
		return -EAGAIN;

	iowrite32(1 << sysc_ch->chan_bit,
		  rcar_sysc_base + sysc_ch->chan_offs + reg_offs);

	return 0;
}

static int rcar_sysc_pwr_off(struct rcar_sysc_ch *sysc_ch)
{
	return rcar_sysc_pwr_on_off(sysc_ch, 0, PWROFFCR_OFFS);
}

static int rcar_sysc_pwr_on(struct rcar_sysc_ch *sysc_ch)
{
	return rcar_sysc_pwr_on_off(sysc_ch, 1, PWRONCR_OFFS);
}

static int rcar_sysc_update(struct rcar_sysc_ch *sysc_ch,
			    int (*on_off_fn)(struct rcar_sysc_ch *))
{
	unsigned int isr_mask = 1 << sysc_ch->isr_bit;
	unsigned int chan_mask = 1 << 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);

	do {
		ret = on_off_fn(sysc_ch);
		if (ret)
			goto out;

		status = ioread32(rcar_sysc_base +
				  sysc_ch->chan_offs + PWRER_OFFS);
	} while (status & chan_mask);

	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(struct rcar_sysc_ch *sysc_ch)
{
	return rcar_sysc_update(sysc_ch, rcar_sysc_pwr_off);
}

int rcar_sysc_power_up(struct rcar_sysc_ch *sysc_ch)
{
	return rcar_sysc_update(sysc_ch, rcar_sysc_pwr_on);
}

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

	st = ioread32(rcar_sysc_base + sysc_ch->chan_offs + PWRSR_OFFS);
	if (st & (1 << 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;
}