/*
 * TI Common Platform Interrupt Controller (cp_intc) driver
 *
 * Author: Steve Chen <schen@mvista.com>
 * Copyright (C) 2008-2009, MontaVista Software, Inc. <source@mvista.com>
 *
 * This file is licensed under the terms of the GNU General Public License
 * version 2. This program is licensed "as is" without any warranty of any
 * kind, whether express or implied.
 */

#include <linux/export.h>
#include <linux/init.h>
#include <linux/irq.h>
#include <linux/irqchip.h>
#include <linux/irqdomain.h>
#include <linux/io.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>

#include <asm/exception.h>
#include <mach/common.h>
#include "cp_intc.h"

#define DAVINCI_CP_INTC_PRI_INDX_MASK		GENMASK(9, 0)
#define DAVINCI_CP_INTC_GPIR_NONE		BIT(31)

static void __iomem *davinci_intc_base;

static inline unsigned int cp_intc_read(unsigned offset)
{
	return __raw_readl(davinci_intc_base + offset);
}

static inline void cp_intc_write(unsigned long value, unsigned offset)
{
	__raw_writel(value, davinci_intc_base + offset);
}

static void cp_intc_ack_irq(struct irq_data *d)
{
	cp_intc_write(d->hwirq, CP_INTC_SYS_STAT_IDX_CLR);
}

/* Disable interrupt */
static void cp_intc_mask_irq(struct irq_data *d)
{
	/* XXX don't know why we need to disable nIRQ here... */
	cp_intc_write(1, CP_INTC_HOST_ENABLE_IDX_CLR);
	cp_intc_write(d->hwirq, CP_INTC_SYS_ENABLE_IDX_CLR);
	cp_intc_write(1, CP_INTC_HOST_ENABLE_IDX_SET);
}

/* Enable interrupt */
static void cp_intc_unmask_irq(struct irq_data *d)
{
	cp_intc_write(d->hwirq, CP_INTC_SYS_ENABLE_IDX_SET);
}

static int cp_intc_set_irq_type(struct irq_data *d, unsigned int flow_type)
{
	unsigned reg		= BIT_WORD(d->hwirq);
	unsigned mask		= BIT_MASK(d->hwirq);
	unsigned polarity	= cp_intc_read(CP_INTC_SYS_POLARITY(reg));
	unsigned type		= cp_intc_read(CP_INTC_SYS_TYPE(reg));

	switch (flow_type) {
	case IRQ_TYPE_EDGE_RISING:
		polarity |= mask;
		type |= mask;
		break;
	case IRQ_TYPE_EDGE_FALLING:
		polarity &= ~mask;
		type |= mask;
		break;
	case IRQ_TYPE_LEVEL_HIGH:
		polarity |= mask;
		type &= ~mask;
		break;
	case IRQ_TYPE_LEVEL_LOW:
		polarity &= ~mask;
		type &= ~mask;
		break;
	default:
		return -EINVAL;
	}

	cp_intc_write(polarity, CP_INTC_SYS_POLARITY(reg));
	cp_intc_write(type, CP_INTC_SYS_TYPE(reg));

	return 0;
}

static struct irq_chip cp_intc_irq_chip = {
	.name		= "cp_intc",
	.irq_ack	= cp_intc_ack_irq,
	.irq_mask	= cp_intc_mask_irq,
	.irq_unmask	= cp_intc_unmask_irq,
	.irq_set_type	= cp_intc_set_irq_type,
	.flags		= IRQCHIP_SKIP_SET_WAKE,
};

static struct irq_domain *cp_intc_domain;

static asmlinkage void __exception_irq_entry
cp_intc_handle_irq(struct pt_regs *regs)
{
	int gpir, irqnr, none;

	/*
	 * The interrupt number is in first ten bits. The NONE field set to 1
	 * indicates a spurious irq.
	 */

	gpir = cp_intc_read(CP_INTC_PRIO_IDX);
	irqnr = gpir & DAVINCI_CP_INTC_PRI_INDX_MASK;
	none = gpir & DAVINCI_CP_INTC_GPIR_NONE;

	if (unlikely(none)) {
		pr_err_once("%s: spurious irq!\n", __func__);
		return;
	}

	handle_domain_irq(cp_intc_domain, irqnr, regs);
}

static int cp_intc_host_map(struct irq_domain *h, unsigned int virq,
			  irq_hw_number_t hw)
{
	pr_debug("cp_intc_host_map(%d, 0x%lx)\n", virq, hw);

	irq_set_chip(virq, &cp_intc_irq_chip);
	irq_set_probe(virq);
	irq_set_handler(virq, handle_edge_irq);
	return 0;
}

static const struct irq_domain_ops cp_intc_host_ops = {
	.map = cp_intc_host_map,
	.xlate = irq_domain_xlate_onetwocell,
};

int __init cp_intc_of_init(struct device_node *node, struct device_node *parent)
{
	u32 num_irq		= davinci_soc_info.intc_irq_num;
	u8 *irq_prio		= davinci_soc_info.intc_irq_prios;
	unsigned num_reg	= BITS_TO_LONGS(num_irq);
	int i, irq_base;

	if (node) {
		davinci_intc_base = of_iomap(node, 0);
		if (of_property_read_u32(node, "ti,intc-size", &num_irq))
			pr_warn("unable to get intc-size, default to %d\n",
				num_irq);
	} else {
		davinci_intc_base = ioremap(davinci_soc_info.intc_base, SZ_8K);
	}
	if (WARN_ON(!davinci_intc_base))
		return -EINVAL;

	cp_intc_write(0, CP_INTC_GLOBAL_ENABLE);

	/* Disable all host interrupts */
	cp_intc_write(0, CP_INTC_HOST_ENABLE(0));

	/* Disable system interrupts */
	for (i = 0; i < num_reg; i++)
		cp_intc_write(~0, CP_INTC_SYS_ENABLE_CLR(i));

	/* Set to normal mode, no nesting, no priority hold */
	cp_intc_write(0, CP_INTC_CTRL);
	cp_intc_write(0, CP_INTC_HOST_CTRL);

	/* Clear system interrupt status */
	for (i = 0; i < num_reg; i++)
		cp_intc_write(~0, CP_INTC_SYS_STAT_CLR(i));

	/* Enable nIRQ (what about nFIQ?) */
	cp_intc_write(1, CP_INTC_HOST_ENABLE_IDX_SET);

	/*
	 * Priority is determined by host channel: lower channel number has
	 * higher priority i.e. channel 0 has highest priority and channel 31
	 * had the lowest priority.
	 */
	num_reg = (num_irq + 3) >> 2;	/* 4 channels per register */
	if (irq_prio) {
		unsigned j, k;
		u32 val;

		for (k = i = 0; i < num_reg; i++) {
			for (val = j = 0; j < 4; j++, k++) {
				val >>= 8;
				if (k < num_irq)
					val |= irq_prio[k] << 24;
			}

			cp_intc_write(val, CP_INTC_CHAN_MAP(i));
		}
	} else	{
		/*
		 * Default everything to channel 15 if priority not specified.
		 * Note that channel 0-1 are mapped to nFIQ and channels 2-31
		 * are mapped to nIRQ.
		 */
		for (i = 0; i < num_reg; i++)
			cp_intc_write(0x0f0f0f0f, CP_INTC_CHAN_MAP(i));
	}

	irq_base = irq_alloc_descs(-1, 0, num_irq, 0);
	if (irq_base < 0) {
		pr_warn("Couldn't allocate IRQ numbers\n");
		irq_base = 0;
	}

	/* create a legacy host */
	cp_intc_domain = irq_domain_add_legacy(node, num_irq,
					irq_base, 0, &cp_intc_host_ops, NULL);

	if (!cp_intc_domain) {
		pr_err("cp_intc: failed to allocate irq host!\n");
		return -EINVAL;
	}

	set_handle_irq(cp_intc_handle_irq);

	/* Enable global interrupt */
	cp_intc_write(1, CP_INTC_GLOBAL_ENABLE);

	return 0;
}

void __init cp_intc_init(void)
{
	cp_intc_of_init(NULL, NULL);
}

IRQCHIP_DECLARE(cp_intc, "ti,cp-intc", cp_intc_of_init);