/*
 * arch/powerpc/platforms/embedded6xx/hlwd-pic.c
 *
 * Nintendo Wii "Hollywood" interrupt controller support.
 * Copyright (C) 2009 The GameCube Linux Team
 * Copyright (C) 2009 Albert Herranz
 *
 * 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, or (at your option) any later version.
 *
 */
#define DRV_MODULE_NAME "hlwd-pic"
#define pr_fmt(fmt) DRV_MODULE_NAME ": " fmt

#include <linux/kernel.h>
#include <linux/irq.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <asm/io.h>

#include "hlwd-pic.h"

#define HLWD_NR_IRQS	32

/*
 * Each interrupt has a corresponding bit in both
 * the Interrupt Cause (ICR) and Interrupt Mask (IMR) registers.
 *
 * Enabling/disabling an interrupt line involves asserting/clearing
 * the corresponding bit in IMR. ACK'ing a request simply involves
 * asserting the corresponding bit in ICR.
 */
#define HW_BROADWAY_ICR		0x00
#define HW_BROADWAY_IMR		0x04
#define HW_STARLET_ICR		0x08
#define HW_STARLET_IMR		0x0c


/*
 * IRQ chip hooks.
 *
 */

static void hlwd_pic_mask_and_ack(struct irq_data *d)
{
	int irq = irqd_to_hwirq(d);
	void __iomem *io_base = irq_data_get_irq_chip_data(d);
	u32 mask = 1 << irq;

	clrbits32(io_base + HW_BROADWAY_IMR, mask);
	out_be32(io_base + HW_BROADWAY_ICR, mask);
}

static void hlwd_pic_ack(struct irq_data *d)
{
	int irq = irqd_to_hwirq(d);
	void __iomem *io_base = irq_data_get_irq_chip_data(d);

	out_be32(io_base + HW_BROADWAY_ICR, 1 << irq);
}

static void hlwd_pic_mask(struct irq_data *d)
{
	int irq = irqd_to_hwirq(d);
	void __iomem *io_base = irq_data_get_irq_chip_data(d);

	clrbits32(io_base + HW_BROADWAY_IMR, 1 << irq);
}

static void hlwd_pic_unmask(struct irq_data *d)
{
	int irq = irqd_to_hwirq(d);
	void __iomem *io_base = irq_data_get_irq_chip_data(d);

	setbits32(io_base + HW_BROADWAY_IMR, 1 << irq);

	/* Make sure the ARM (aka. Starlet) doesn't handle this interrupt. */
	clrbits32(io_base + HW_STARLET_IMR, 1 << irq);
}


static struct irq_chip hlwd_pic = {
	.name		= "hlwd-pic",
	.irq_ack	= hlwd_pic_ack,
	.irq_mask_ack	= hlwd_pic_mask_and_ack,
	.irq_mask	= hlwd_pic_mask,
	.irq_unmask	= hlwd_pic_unmask,
};

/*
 * IRQ host hooks.
 *
 */

static struct irq_domain *hlwd_irq_host;

static int hlwd_pic_map(struct irq_domain *h, unsigned int virq,
			   irq_hw_number_t hwirq)
{
	irq_set_chip_data(virq, h->host_data);
	irq_set_status_flags(virq, IRQ_LEVEL);
	irq_set_chip_and_handler(virq, &hlwd_pic, handle_level_irq);
	return 0;
}

static const struct irq_domain_ops hlwd_irq_domain_ops = {
	.map = hlwd_pic_map,
};

static unsigned int __hlwd_pic_get_irq(struct irq_domain *h)
{
	void __iomem *io_base = h->host_data;
	int irq;
	u32 irq_status;

	irq_status = in_be32(io_base + HW_BROADWAY_ICR) &
		     in_be32(io_base + HW_BROADWAY_IMR);
	if (irq_status == 0)
		return 0;	/* no more IRQs pending */

	irq = __ffs(irq_status);
	return irq_linear_revmap(h, irq);
}

static void hlwd_pic_irq_cascade(struct irq_desc *desc)
{
	struct irq_chip *chip = irq_desc_get_chip(desc);
	struct irq_domain *irq_domain = irq_desc_get_handler_data(desc);
	unsigned int virq;

	raw_spin_lock(&desc->lock);
	chip->irq_mask(&desc->irq_data); /* IRQ_LEVEL */
	raw_spin_unlock(&desc->lock);

	virq = __hlwd_pic_get_irq(irq_domain);
	if (virq)
		generic_handle_irq(virq);
	else
		pr_err("spurious interrupt!\n");

	raw_spin_lock(&desc->lock);
	chip->irq_ack(&desc->irq_data); /* IRQ_LEVEL */
	if (!irqd_irq_disabled(&desc->irq_data) && chip->irq_unmask)
		chip->irq_unmask(&desc->irq_data);
	raw_spin_unlock(&desc->lock);
}

/*
 * Platform hooks.
 *
 */

static void __hlwd_quiesce(void __iomem *io_base)
{
	/* mask and ack all IRQs */
	out_be32(io_base + HW_BROADWAY_IMR, 0);
	out_be32(io_base + HW_BROADWAY_ICR, 0xffffffff);
}

static struct irq_domain *hlwd_pic_init(struct device_node *np)
{
	struct irq_domain *irq_domain;
	struct resource res;
	void __iomem *io_base;
	int retval;

	retval = of_address_to_resource(np, 0, &res);
	if (retval) {
		pr_err("no io memory range found\n");
		return NULL;
	}
	io_base = ioremap(res.start, resource_size(&res));
	if (!io_base) {
		pr_err("ioremap failed\n");
		return NULL;
	}

	pr_info("controller at 0x%pa mapped to 0x%p\n", &res.start, io_base);

	__hlwd_quiesce(io_base);

	irq_domain = irq_domain_add_linear(np, HLWD_NR_IRQS,
					   &hlwd_irq_domain_ops, io_base);
	if (!irq_domain) {
		pr_err("failed to allocate irq_domain\n");
		iounmap(io_base);
		return NULL;
	}

	return irq_domain;
}

unsigned int hlwd_pic_get_irq(void)
{
	return __hlwd_pic_get_irq(hlwd_irq_host);
}

/*
 * Probe function.
 *
 */

void hlwd_pic_probe(void)
{
	struct irq_domain *host;
	struct device_node *np;
	const u32 *interrupts;
	int cascade_virq;

	for_each_compatible_node(np, NULL, "nintendo,hollywood-pic") {
		interrupts = of_get_property(np, "interrupts", NULL);
		if (interrupts) {
			host = hlwd_pic_init(np);
			BUG_ON(!host);
			cascade_virq = irq_of_parse_and_map(np, 0);
			irq_set_handler_data(cascade_virq, host);
			irq_set_chained_handler(cascade_virq,
						hlwd_pic_irq_cascade);
			hlwd_irq_host = host;
			of_node_put(np);
			break;
		}
	}
}

/**
 * hlwd_quiesce() - quiesce hollywood irq controller
 *
 * Mask and ack all interrupt sources.
 *
 */
void hlwd_quiesce(void)
{
	void __iomem *io_base = hlwd_irq_host->host_data;

	__hlwd_quiesce(io_base);
}