/*
 * TI LP8788 MFD - interrupt handler
 *
 * Copyright 2012 Texas Instruments
 *
 * Author: Milo(Woogyom) Kim <milo.kim@ti.com>
 *
 * 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/delay.h>
#include <linux/err.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/irqdomain.h>
#include <linux/device.h>
#include <linux/mfd/lp8788.h>
#include <linux/module.h>
#include <linux/slab.h>

/* register address */
#define LP8788_INT_1			0x00
#define LP8788_INTEN_1			0x03

#define BASE_INTEN_ADDR			LP8788_INTEN_1
#define SIZE_REG			8
#define NUM_REGS			3

/*
 * struct lp8788_irq_data
 * @lp               : used for accessing to lp8788 registers
 * @irq_lock         : mutex for enabling/disabling the interrupt
 * @domain           : IRQ domain for handling nested interrupt
 * @enabled          : status of enabled interrupt
 */
struct lp8788_irq_data {
	struct lp8788 *lp;
	struct mutex irq_lock;
	struct irq_domain *domain;
	int enabled[LP8788_INT_MAX];
};

static inline u8 _irq_to_addr(enum lp8788_int_id id)
{
	return id / SIZE_REG;
}

static inline u8 _irq_to_enable_addr(enum lp8788_int_id id)
{
	return _irq_to_addr(id) + BASE_INTEN_ADDR;
}

static inline u8 _irq_to_mask(enum lp8788_int_id id)
{
	return 1 << (id % SIZE_REG);
}

static inline u8 _irq_to_val(enum lp8788_int_id id, int enable)
{
	return enable << (id % SIZE_REG);
}

static void lp8788_irq_enable(struct irq_data *data)
{
	struct lp8788_irq_data *irqd = irq_data_get_irq_chip_data(data);

	irqd->enabled[data->hwirq] = 1;
}

static void lp8788_irq_disable(struct irq_data *data)
{
	struct lp8788_irq_data *irqd = irq_data_get_irq_chip_data(data);

	irqd->enabled[data->hwirq] = 0;
}

static void lp8788_irq_bus_lock(struct irq_data *data)
{
	struct lp8788_irq_data *irqd = irq_data_get_irq_chip_data(data);

	mutex_lock(&irqd->irq_lock);
}

static void lp8788_irq_bus_sync_unlock(struct irq_data *data)
{
	struct lp8788_irq_data *irqd = irq_data_get_irq_chip_data(data);
	enum lp8788_int_id irq = data->hwirq;
	u8 addr, mask, val;

	addr = _irq_to_enable_addr(irq);
	mask = _irq_to_mask(irq);
	val = _irq_to_val(irq, irqd->enabled[irq]);

	lp8788_update_bits(irqd->lp, addr, mask, val);

	mutex_unlock(&irqd->irq_lock);
}

static struct irq_chip lp8788_irq_chip = {
	.name			= "lp8788",
	.irq_enable		= lp8788_irq_enable,
	.irq_disable		= lp8788_irq_disable,
	.irq_bus_lock		= lp8788_irq_bus_lock,
	.irq_bus_sync_unlock	= lp8788_irq_bus_sync_unlock,
};

static irqreturn_t lp8788_irq_handler(int irq, void *ptr)
{
	struct lp8788_irq_data *irqd = ptr;
	struct lp8788 *lp = irqd->lp;
	u8 status[NUM_REGS], addr, mask;
	bool handled;
	int i;

	if (lp8788_read_multi_bytes(lp, LP8788_INT_1, status, NUM_REGS))
		return IRQ_NONE;

	for (i = 0 ; i < LP8788_INT_MAX ; i++) {
		addr = _irq_to_addr(i);
		mask = _irq_to_mask(i);

		/* reporting only if the irq is enabled */
		if (status[addr] & mask) {
			handle_nested_irq(irq_find_mapping(irqd->domain, i));
			handled = true;
		}
	}

	return handled ? IRQ_HANDLED : IRQ_NONE;
}

static int lp8788_irq_map(struct irq_domain *d, unsigned int virq,
			irq_hw_number_t hwirq)
{
	struct lp8788_irq_data *irqd = d->host_data;
	struct irq_chip *chip = &lp8788_irq_chip;

	irq_set_chip_data(virq, irqd);
	irq_set_chip_and_handler(virq, chip, handle_edge_irq);
	irq_set_nested_thread(virq, 1);
	irq_set_noprobe(virq);

	return 0;
}

static const struct irq_domain_ops lp8788_domain_ops = {
	.map = lp8788_irq_map,
};

int lp8788_irq_init(struct lp8788 *lp, int irq)
{
	struct lp8788_irq_data *irqd;
	int ret;

	if (irq <= 0) {
		dev_warn(lp->dev, "invalid irq number: %d\n", irq);
		return 0;
	}

	irqd = devm_kzalloc(lp->dev, sizeof(*irqd), GFP_KERNEL);
	if (!irqd)
		return -ENOMEM;

	irqd->lp = lp;
	irqd->domain = irq_domain_add_linear(lp->dev->of_node, LP8788_INT_MAX,
					&lp8788_domain_ops, irqd);
	if (!irqd->domain) {
		dev_err(lp->dev, "failed to add irq domain err\n");
		return -EINVAL;
	}

	lp->irqdm = irqd->domain;
	mutex_init(&irqd->irq_lock);

	ret = request_threaded_irq(irq, NULL, lp8788_irq_handler,
				IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
				"lp8788-irq", irqd);
	if (ret) {
		dev_err(lp->dev, "failed to create a thread for IRQ_N\n");
		return ret;
	}

	lp->irq = irq;

	return 0;
}

void lp8788_irq_exit(struct lp8788 *lp)
{
	if (lp->irq)
		free_irq(lp->irq, lp->irqdm);
}