/*
 * arch/powerpc/sysdev/uic.c
 *
 * IBM PowerPC 4xx Universal Interrupt Controller
 *
 * Copyright 2007 David Gibson <dwg@au1.ibm.com>, IBM Corporation.
 *
 * 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/kernel.h>
#include <linux/init.h>
#include <linux/errno.h>
#include <linux/reboot.h>
#include <linux/slab.h>
#include <linux/stddef.h>
#include <linux/sched.h>
#include <linux/signal.h>
#include <linux/sysdev.h>
#include <linux/device.h>
#include <linux/bootmem.h>
#include <linux/spinlock.h>
#include <linux/irq.h>
#include <linux/interrupt.h>
#include <linux/kernel_stat.h>
#include <asm/irq.h>
#include <asm/io.h>
#include <asm/prom.h>
#include <asm/dcr.h>

#define NR_UIC_INTS     32

#define UIC_SR          0x0
#define UIC_ER          0x2
#define UIC_CR          0x3
#define UIC_PR          0x4
#define UIC_TR          0x5
#define UIC_MSR         0x6
#define UIC_VR          0x7
#define UIC_VCR         0x8

#define uic_irq_to_hw(virq)     (irq_map[virq].hwirq)

struct uic *primary_uic;

struct uic {
        int index;
        int dcrbase;

        spinlock_t lock;

        /* The remapper for this UIC */
        struct irq_host *irqhost;
};

static void uic_unmask_irq(unsigned int virq)
{
        struct irq_desc *desc = irq_to_desc(virq);
        struct uic *uic = get_irq_chip_data(virq);
        unsigned int src = uic_irq_to_hw(virq);
        unsigned long flags;
        u32 er, sr;

        sr = 1 << (31-src);
        spin_lock_irqsave(&uic->lock, flags);
        /* ack level-triggered interrupts here */
        if (desc->status & IRQ_LEVEL)
                mtdcr(uic->dcrbase + UIC_SR, sr);
        er = mfdcr(uic->dcrbase + UIC_ER);
        er |= sr;
        mtdcr(uic->dcrbase + UIC_ER, er);
        spin_unlock_irqrestore(&uic->lock, flags);
}

static void uic_mask_irq(unsigned int virq)
{
        struct uic *uic = get_irq_chip_data(virq);
        unsigned int src = uic_irq_to_hw(virq);
        unsigned long flags;
        u32 er;

        spin_lock_irqsave(&uic->lock, flags);
        er = mfdcr(uic->dcrbase + UIC_ER);
        er &= ~(1 << (31 - src));
        mtdcr(uic->dcrbase + UIC_ER, er);
        spin_unlock_irqrestore(&uic->lock, flags);
}

static void uic_ack_irq(unsigned int virq)
{
        struct uic *uic = get_irq_chip_data(virq);
        unsigned int src = uic_irq_to_hw(virq);
        unsigned long flags;

        spin_lock_irqsave(&uic->lock, flags);
        mtdcr(uic->dcrbase + UIC_SR, 1 << (31-src));
        spin_unlock_irqrestore(&uic->lock, flags);
}

static void uic_mask_ack_irq(unsigned int virq)
{
        struct irq_desc *desc = irq_to_desc(virq);
        struct uic *uic = get_irq_chip_data(virq);
        unsigned int src = uic_irq_to_hw(virq);
        unsigned long flags;
        u32 er, sr;

        sr = 1 << (31-src);
        spin_lock_irqsave(&uic->lock, flags);
        er = mfdcr(uic->dcrbase + UIC_ER);
        er &= ~sr;
        mtdcr(uic->dcrbase + UIC_ER, er);
        /* On the UIC, acking (i.e. clearing the SR bit)
         * a level irq will have no effect if the interrupt
         * is still asserted by the device, even if
         * the interrupt is already masked. Therefore
         * we only ack the egde interrupts here, while
         * level interrupts are ack'ed after the actual
         * isr call in the uic_unmask_irq()
         */
        if (!(desc->status & IRQ_LEVEL))
                mtdcr(uic->dcrbase + UIC_SR, sr);
        spin_unlock_irqrestore(&uic->lock, flags);
}

static int uic_set_irq_type(unsigned int virq, unsigned int flow_type)
{
        struct uic *uic = get_irq_chip_data(virq);
        unsigned int src = uic_irq_to_hw(virq);
        struct irq_desc *desc = irq_to_desc(virq);
        unsigned long flags;
        int trigger, polarity;
        u32 tr, pr, mask;

        switch (flow_type & IRQ_TYPE_SENSE_MASK) {
        case IRQ_TYPE_NONE:
                uic_mask_irq(virq);
                return 0;

        case IRQ_TYPE_EDGE_RISING:
                trigger = 1; polarity = 1;
                break;
        case IRQ_TYPE_EDGE_FALLING:
                trigger = 1; polarity = 0;
                break;
        case IRQ_TYPE_LEVEL_HIGH:
                trigger = 0; polarity = 1;
                break;
        case IRQ_TYPE_LEVEL_LOW:
                trigger = 0; polarity = 0;
                break;
        default:
                return -EINVAL;
        }

        mask = ~(1 << (31 - src));

        spin_lock_irqsave(&uic->lock, flags);
        tr = mfdcr(uic->dcrbase + UIC_TR);
        pr = mfdcr(uic->dcrbase + UIC_PR);
        tr = (tr & mask) | (trigger << (31-src));
        pr = (pr & mask) | (polarity << (31-src));

        mtdcr(uic->dcrbase + UIC_PR, pr);
        mtdcr(uic->dcrbase + UIC_TR, tr);

        desc->status &= ~(IRQ_TYPE_SENSE_MASK | IRQ_LEVEL);
        desc->status |= flow_type & IRQ_TYPE_SENSE_MASK;
        if (!trigger)
                desc->status |= IRQ_LEVEL;

        spin_unlock_irqrestore(&uic->lock, flags);

        return 0;
}

static struct irq_chip uic_irq_chip = {
        .name           = "UIC",
        .unmask         = uic_unmask_irq,
        .mask           = uic_mask_irq,
        .mask_ack       = uic_mask_ack_irq,
        .ack            = uic_ack_irq,
        .set_type       = uic_set_irq_type,
};

static int uic_host_map(struct irq_host *h, unsigned int virq,
                        irq_hw_number_t hw)
{
        struct uic *uic = h->host_data;

        set_irq_chip_data(virq, uic);
        /* Despite the name, handle_level_irq() works for both level
         * and edge irqs on UIC.  FIXME: check this is correct */
        set_irq_chip_and_handler(virq, &uic_irq_chip, handle_level_irq);

        /* Set default irq type */
        set_irq_type(virq, IRQ_TYPE_NONE);

        return 0;
}

static int uic_host_xlate(struct irq_host *h, struct device_node *ct,
                          const u32 *intspec, unsigned int intsize,
                          irq_hw_number_t *out_hwirq, unsigned int *out_type)

{
        /* UIC intspecs must have 2 cells */
        BUG_ON(intsize != 2);
        *out_hwirq = intspec[0];
        *out_type = intspec[1];
        return 0;
}

static struct irq_host_ops uic_host_ops = {
        .map    = uic_host_map,
        .xlate  = uic_host_xlate,
};

void uic_irq_cascade(unsigned int virq, struct irq_desc *desc)
{
        struct uic *uic = get_irq_data(virq);
        u32 msr;
        int src;
        int subvirq;

        raw_spin_lock(&desc->lock);
        if (desc->status & IRQ_LEVEL)
                desc->chip->mask(virq);
        else
                desc->chip->mask_ack(virq);
        raw_spin_unlock(&desc->lock);

        msr = mfdcr(uic->dcrbase + UIC_MSR);
        if (!msr) /* spurious interrupt */
                goto uic_irq_ret;

        src = 32 - ffs(msr);

        subvirq = irq_linear_revmap(uic->irqhost, src);
        generic_handle_irq(subvirq);

uic_irq_ret:
        raw_spin_lock(&desc->lock);
        if (desc->status & IRQ_LEVEL)
                desc->chip->ack(virq);
        if (!(desc->status & IRQ_DISABLED) && desc->chip->unmask)
                desc->chip->unmask(virq);
        raw_spin_unlock(&desc->lock);
}

static struct uic * __init uic_init_one(struct device_node *node)
{
        struct uic *uic;
        const u32 *indexp, *dcrreg;
        int len;

        BUG_ON(! of_device_is_compatible(node, "ibm,uic"));

        uic = kzalloc(sizeof(*uic), GFP_KERNEL);
        if (! uic)
                return NULL; /* FIXME: panic? */

        spin_lock_init(&uic->lock);
        indexp = of_get_property(node, "cell-index", &len);
        if (!indexp || (len != sizeof(u32))) {
                printk(KERN_ERR "uic: Device node %s has missing or invalid "
                       "cell-index property\n", node->full_name);
                return NULL;
        }
        uic->index = *indexp;

        dcrreg = of_get_property(node, "dcr-reg", &len);
        if (!dcrreg || (len != 2*sizeof(u32))) {
                printk(KERN_ERR "uic: Device node %s has missing or invalid "
                       "dcr-reg property\n", node->full_name);
                return NULL;
        }
        uic->dcrbase = *dcrreg;

        uic->irqhost = irq_alloc_host(node, IRQ_HOST_MAP_LINEAR,
                                      NR_UIC_INTS, &uic_host_ops, -1);
        if (! uic->irqhost)
                return NULL; /* FIXME: panic? */

        uic->irqhost->host_data = uic;

        /* Start with all interrupts disabled, level and non-critical */
        mtdcr(uic->dcrbase + UIC_ER, 0);
        mtdcr(uic->dcrbase + UIC_CR, 0);
        mtdcr(uic->dcrbase + UIC_TR, 0);
        /* Clear any pending interrupts, in case the firmware left some */
        mtdcr(uic->dcrbase + UIC_SR, 0xffffffff);

        printk ("UIC%d (%d IRQ sources) at DCR 0x%x\n", uic->index,
                NR_UIC_INTS, uic->dcrbase);

        return uic;
}

void __init uic_init_tree(void)
{
        struct device_node *np;
        struct uic *uic;
        const u32 *interrupts;

        /* First locate and initialize the top-level UIC */
        for_each_compatible_node(np, NULL, "ibm,uic") {
                interrupts = of_get_property(np, "interrupts", NULL);
                if (!interrupts)
                        break;
        }

        BUG_ON(!np); /* uic_init_tree() assumes there's a UIC as the
                      * top-level interrupt controller */
        primary_uic = uic_init_one(np);
        if (!primary_uic)
                panic("Unable to initialize primary UIC %s\n", np->full_name);

        irq_set_default_host(primary_uic->irqhost);
        of_node_put(np);

        /* The scan again for cascaded UICs */
        for_each_compatible_node(np, NULL, "ibm,uic") {
                interrupts = of_get_property(np, "interrupts", NULL);
                if (interrupts) {
                        /* Secondary UIC */
                        int cascade_virq;

                        uic = uic_init_one(np);
                        if (! uic)
                                panic("Unable to initialize a secondary UIC %s\n",
                                      np->full_name);

                        cascade_virq = irq_of_parse_and_map(np, 0);

                        set_irq_data(cascade_virq, uic);
                        set_irq_chained_handler(cascade_virq, uic_irq_cascade);

                        /* FIXME: setup critical cascade?? */
                }
        }
}

/* Return an interrupt vector or NO_IRQ if no interrupt is pending. */
unsigned int uic_get_irq(void)
{
        u32 msr;
        int src;

        BUG_ON(! primary_uic);

        msr = mfdcr(primary_uic->dcrbase + UIC_MSR);
        src = 32 - ffs(msr);

        return irq_linear_revmap(primary_uic->irqhost, src);
}