/*
 * Copyright (C) 2014 Mans Rullgard <mans@mansr.com>
 *
 * 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.
 */

#include <linux/init.h>
#include <linux/irq.h>
#include <linux/irqchip.h>
#include <linux/irqchip/chained_irq.h>
#include <linux/ioport.h>
#include <linux/io.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <linux/slab.h>

#define IRQ0_CTL_BASE		0x0000
#define IRQ1_CTL_BASE		0x0100
#define EDGE_CTL_BASE		0x0200
#define IRQ2_CTL_BASE		0x0300

#define IRQ_CTL_HI		0x18
#define EDGE_CTL_HI		0x20

#define IRQ_STATUS		0x00
#define IRQ_RAWSTAT		0x04
#define IRQ_EN_SET		0x08
#define IRQ_EN_CLR		0x0c
#define IRQ_SOFT_SET		0x10
#define IRQ_SOFT_CLR		0x14

#define EDGE_STATUS		0x00
#define EDGE_RAWSTAT		0x04
#define EDGE_CFG_RISE		0x08
#define EDGE_CFG_FALL		0x0c
#define EDGE_CFG_RISE_SET	0x10
#define EDGE_CFG_RISE_CLR	0x14
#define EDGE_CFG_FALL_SET	0x18
#define EDGE_CFG_FALL_CLR	0x1c

struct tangox_irq_chip {
	void __iomem *base;
	unsigned long ctl;
};

static inline u32 intc_readl(struct tangox_irq_chip *chip, int reg)
{
	return readl_relaxed(chip->base + reg);
}

static inline void intc_writel(struct tangox_irq_chip *chip, int reg, u32 val)
{
	writel_relaxed(val, chip->base + reg);
}

static void tangox_dispatch_irqs(struct irq_domain *dom, unsigned int status,
				 int base)
{
	unsigned int hwirq;
	unsigned int virq;

	while (status) {
		hwirq = __ffs(status);
		virq = irq_find_mapping(dom, base + hwirq);
		if (virq)
			generic_handle_irq(virq);
		status &= ~BIT(hwirq);
	}
}

static void tangox_irq_handler(struct irq_desc *desc)
{
	struct irq_domain *dom = irq_desc_get_handler_data(desc);
	struct irq_chip *host_chip = irq_desc_get_chip(desc);
	struct tangox_irq_chip *chip = dom->host_data;
	unsigned int status_lo, status_hi;

	chained_irq_enter(host_chip, desc);

	status_lo = intc_readl(chip, chip->ctl + IRQ_STATUS);
	status_hi = intc_readl(chip, chip->ctl + IRQ_CTL_HI + IRQ_STATUS);

	tangox_dispatch_irqs(dom, status_lo, 0);
	tangox_dispatch_irqs(dom, status_hi, 32);

	chained_irq_exit(host_chip, desc);
}

static int tangox_irq_set_type(struct irq_data *d, unsigned int flow_type)
{
	struct irq_chip_generic *gc = irq_data_get_irq_chip_data(d);
	struct tangox_irq_chip *chip = gc->domain->host_data;
	struct irq_chip_regs *regs = &gc->chip_types[0].regs;

	switch (flow_type & IRQ_TYPE_SENSE_MASK) {
	case IRQ_TYPE_EDGE_RISING:
		intc_writel(chip, regs->type + EDGE_CFG_RISE_SET, d->mask);
		intc_writel(chip, regs->type + EDGE_CFG_FALL_CLR, d->mask);
		break;

	case IRQ_TYPE_EDGE_FALLING:
		intc_writel(chip, regs->type + EDGE_CFG_RISE_CLR, d->mask);
		intc_writel(chip, regs->type + EDGE_CFG_FALL_SET, d->mask);
		break;

	case IRQ_TYPE_LEVEL_HIGH:
		intc_writel(chip, regs->type + EDGE_CFG_RISE_CLR, d->mask);
		intc_writel(chip, regs->type + EDGE_CFG_FALL_CLR, d->mask);
		break;

	case IRQ_TYPE_LEVEL_LOW:
		intc_writel(chip, regs->type + EDGE_CFG_RISE_SET, d->mask);
		intc_writel(chip, regs->type + EDGE_CFG_FALL_SET, d->mask);
		break;

	default:
		pr_err("Invalid trigger mode %x for IRQ %d\n",
		       flow_type, d->irq);
		return -EINVAL;
	}

	return irq_setup_alt_chip(d, flow_type);
}

static void __init tangox_irq_init_chip(struct irq_chip_generic *gc,
					unsigned long ctl_offs,
					unsigned long edge_offs)
{
	struct tangox_irq_chip *chip = gc->domain->host_data;
	struct irq_chip_type *ct = gc->chip_types;
	unsigned long ctl_base = chip->ctl + ctl_offs;
	unsigned long edge_base = EDGE_CTL_BASE + edge_offs;
	int i;

	gc->reg_base = chip->base;
	gc->unused = 0;

	for (i = 0; i < 2; i++) {
		ct[i].chip.irq_ack = irq_gc_ack_set_bit;
		ct[i].chip.irq_mask = irq_gc_mask_disable_reg;
		ct[i].chip.irq_mask_ack = irq_gc_mask_disable_and_ack_set;
		ct[i].chip.irq_unmask = irq_gc_unmask_enable_reg;
		ct[i].chip.irq_set_type = tangox_irq_set_type;
		ct[i].chip.name = gc->domain->name;

		ct[i].regs.enable = ctl_base + IRQ_EN_SET;
		ct[i].regs.disable = ctl_base + IRQ_EN_CLR;
		ct[i].regs.ack = edge_base + EDGE_RAWSTAT;
		ct[i].regs.type = edge_base;
	}

	ct[0].type = IRQ_TYPE_LEVEL_MASK;
	ct[0].handler = handle_level_irq;

	ct[1].type = IRQ_TYPE_EDGE_BOTH;
	ct[1].handler = handle_edge_irq;

	intc_writel(chip, ct->regs.disable, 0xffffffff);
	intc_writel(chip, ct->regs.ack, 0xffffffff);
}

static void __init tangox_irq_domain_init(struct irq_domain *dom)
{
	struct irq_chip_generic *gc;
	int i;

	for (i = 0; i < 2; i++) {
		gc = irq_get_domain_generic_chip(dom, i * 32);
		tangox_irq_init_chip(gc, i * IRQ_CTL_HI, i * EDGE_CTL_HI);
	}
}

static int __init tangox_irq_init(void __iomem *base, struct resource *baseres,
				  struct device_node *node)
{
	struct tangox_irq_chip *chip;
	struct irq_domain *dom;
	struct resource res;
	int irq;
	int err;

	irq = irq_of_parse_and_map(node, 0);
	if (!irq)
		panic("%s: failed to get IRQ", node->name);

	err = of_address_to_resource(node, 0, &res);
	if (err)
		panic("%s: failed to get address", node->name);

	chip = kzalloc(sizeof(*chip), GFP_KERNEL);
	chip->ctl = res.start - baseres->start;
	chip->base = base;

	dom = irq_domain_add_linear(node, 64, &irq_generic_chip_ops, chip);
	if (!dom)
		panic("%s: failed to create irqdomain", node->name);

	err = irq_alloc_domain_generic_chips(dom, 32, 2, node->name,
					     handle_level_irq, 0, 0, 0);
	if (err)
		panic("%s: failed to allocate irqchip", node->name);

	tangox_irq_domain_init(dom);

	irq_set_chained_handler_and_data(irq, tangox_irq_handler, dom);

	return 0;
}

static int __init tangox_of_irq_init(struct device_node *node,
				     struct device_node *parent)
{
	struct device_node *c;
	struct resource res;
	void __iomem *base;

	base = of_iomap(node, 0);
	if (!base)
		panic("%s: of_iomap failed", node->name);

	of_address_to_resource(node, 0, &res);

	for_each_child_of_node(node, c)
		tangox_irq_init(base, &res, c);

	return 0;
}
IRQCHIP_DECLARE(tangox_intc, "sigma,smp8642-intc", tangox_of_irq_init);