/*
 *  Aspeed 24XX/25XX I2C Interrupt Controller.
 *
 *  Copyright (C) 2012-2017 ASPEED Technology Inc.
 *  Copyright 2017 IBM Corporation
 *  Copyright 2017 Google, Inc.
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License version 2 as
 *  published by the Free Software Foundation.
 */

#include <linux/irq.h>
#include <linux/irqchip.h>
#include <linux/irqchip/chained_irq.h>
#include <linux/irqdomain.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <linux/io.h>


#define ASPEED_I2C_IC_NUM_BUS 14

struct aspeed_i2c_ic {
	void __iomem		*base;
	int			parent_irq;
	struct irq_domain	*irq_domain;
};

/*
 * The aspeed chip provides a single hardware interrupt for all of the I2C
 * busses, so we use a dummy interrupt chip to translate this single interrupt
 * into multiple interrupts, each associated with a single I2C bus.
 */
static void aspeed_i2c_ic_irq_handler(struct irq_desc *desc)
{
	struct aspeed_i2c_ic *i2c_ic = irq_desc_get_handler_data(desc);
	struct irq_chip *chip = irq_desc_get_chip(desc);
	unsigned long bit, status;
	unsigned int bus_irq;

	chained_irq_enter(chip, desc);
	status = readl(i2c_ic->base);
	for_each_set_bit(bit, &status, ASPEED_I2C_IC_NUM_BUS) {
		bus_irq = irq_find_mapping(i2c_ic->irq_domain, bit);
		generic_handle_irq(bus_irq);
	}
	chained_irq_exit(chip, desc);
}

/*
 * Set simple handler and mark IRQ as valid. Nothing interesting to do here
 * since we are using a dummy interrupt chip.
 */
static int aspeed_i2c_ic_map_irq_domain(struct irq_domain *domain,
					unsigned int irq, irq_hw_number_t hwirq)
{
	irq_set_chip_and_handler(irq, &dummy_irq_chip, handle_simple_irq);
	irq_set_chip_data(irq, domain->host_data);

	return 0;
}

static const struct irq_domain_ops aspeed_i2c_ic_irq_domain_ops = {
	.map = aspeed_i2c_ic_map_irq_domain,
};

static int __init aspeed_i2c_ic_of_init(struct device_node *node,
					struct device_node *parent)
{
	struct aspeed_i2c_ic *i2c_ic;
	int ret = 0;

	i2c_ic = kzalloc(sizeof(*i2c_ic), GFP_KERNEL);
	if (!i2c_ic)
		return -ENOMEM;

	i2c_ic->base = of_iomap(node, 0);
	if (!i2c_ic->base) {
		ret = -ENOMEM;
		goto err_free_ic;
	}

	i2c_ic->parent_irq = irq_of_parse_and_map(node, 0);
	if (!i2c_ic->parent_irq) {
		ret = -EINVAL;
		goto err_iounmap;
	}

	i2c_ic->irq_domain = irq_domain_add_linear(node, ASPEED_I2C_IC_NUM_BUS,
						   &aspeed_i2c_ic_irq_domain_ops,
						   NULL);
	if (!i2c_ic->irq_domain) {
		ret = -ENOMEM;
		goto err_iounmap;
	}

	i2c_ic->irq_domain->name = "aspeed-i2c-domain";

	irq_set_chained_handler_and_data(i2c_ic->parent_irq,
					 aspeed_i2c_ic_irq_handler, i2c_ic);

	pr_info("i2c controller registered, irq %d\n", i2c_ic->parent_irq);

	return 0;

err_iounmap:
	iounmap(i2c_ic->base);
err_free_ic:
	kfree(i2c_ic);
	return ret;
}

IRQCHIP_DECLARE(ast2400_i2c_ic, "aspeed,ast2400-i2c-ic", aspeed_i2c_ic_of_init);
IRQCHIP_DECLARE(ast2500_i2c_ic, "aspeed,ast2500-i2c-ic", aspeed_i2c_ic_of_init);