/*
 * 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/irqdomain.h>
#include <linux/io.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>

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

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 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;
        u32 *host_map           = davinci_soc_info.intc_host_map;
        unsigned num_reg        = BITS_TO_LONGS(num_irq);
        int i, irq_base;

        davinci_intc_type = DAVINCI_INTC_TYPE_CP_INTC;
        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));
        }

        if (host_map)
                for (i = 0; host_map[i] != -1; i++)
                        cp_intc_write(host_map[i], CP_INTC_HOST_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;
        }

        /* 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);
}