/*
 * Interrupt management for most GSC and related devices.
 *
 * (c) Copyright 1999 Alex deVries for The Puffin Group
 * (c) Copyright 1999 Grant Grundler for Hewlett-Packard
 * (c) Copyright 1999 Matthew Wilcox
 * (c) Copyright 2000 Helge Deller
 * (c) Copyright 2001 Matthew Wilcox for Hewlett-Packard
 *
 *      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/bitops.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/ioport.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/types.h>

#include <asm/hardware.h>
#include <asm/io.h>

#include "gsc.h"

#undef DEBUG

#ifdef DEBUG
#define DEBPRINTK printk
#else
#define DEBPRINTK(x,...)
#endif

int gsc_alloc_irq(struct gsc_irq *i)
{
        int irq = txn_alloc_irq(GSC_EIM_WIDTH);
        if (irq < 0) {
                printk("cannot get irq\n");
                return irq;
        }

        i->txn_addr = txn_alloc_addr(irq);
        i->txn_data = txn_alloc_data(irq);
        i->irq = irq;

        return irq;
}

int gsc_claim_irq(struct gsc_irq *i, int irq)
{
        int c = irq;

        irq += CPU_IRQ_BASE; /* virtualize the IRQ first */

        irq = txn_claim_irq(irq);
        if (irq < 0) {
                printk("cannot claim irq %d\n", c);
                return irq;
        }

        i->txn_addr = txn_alloc_addr(irq);
        i->txn_data = txn_alloc_data(irq);
        i->irq = irq;

        return irq;
}

EXPORT_SYMBOL(gsc_alloc_irq);
EXPORT_SYMBOL(gsc_claim_irq);

/* Common interrupt demultiplexer used by Asp, Lasi & Wax.  */
irqreturn_t gsc_asic_intr(int gsc_asic_irq, void *dev)
{
        unsigned long irr;
        struct gsc_asic *gsc_asic = dev;

        irr = gsc_readl(gsc_asic->hpa + OFFSET_IRR);
        if (irr == 0)
                return IRQ_NONE;

        DEBPRINTK("%s intr, mask=0x%x\n", gsc_asic->name, irr);

        do {
                int local_irq = __ffs(irr);
                unsigned int irq = gsc_asic->global_irq[local_irq];
                __do_IRQ(irq);
                irr &= ~(1 << local_irq);
        } while (irr);

        return IRQ_HANDLED;
}

int gsc_find_local_irq(unsigned int irq, int *global_irqs, int limit)
{
        int local_irq;

        for (local_irq = 0; local_irq < limit; local_irq++) {
                if (global_irqs[local_irq] == irq)
                        return local_irq;
        }

        return NO_IRQ;
}

static void gsc_asic_disable_irq(unsigned int irq)
{
        struct irq_desc *desc = irq_to_desc(irq);
        struct gsc_asic *irq_dev = desc->chip_data;
        int local_irq = gsc_find_local_irq(irq, irq_dev->global_irq, 32);
        u32 imr;

        DEBPRINTK(KERN_DEBUG "%s(%d) %s: IMR 0x%x\n", __func__, irq,
                        irq_dev->name, imr);

        /* Disable the IRQ line by clearing the bit in the IMR */
        imr = gsc_readl(irq_dev->hpa + OFFSET_IMR);
        imr &= ~(1 << local_irq);
        gsc_writel(imr, irq_dev->hpa + OFFSET_IMR);
}

static void gsc_asic_enable_irq(unsigned int irq)
{
        struct irq_desc *desc = irq_to_desc(irq);
        struct gsc_asic *irq_dev = desc->chip_data;
        int local_irq = gsc_find_local_irq(irq, irq_dev->global_irq, 32);
        u32 imr;

        DEBPRINTK(KERN_DEBUG "%s(%d) %s: IMR 0x%x\n", __func__, irq,
                        irq_dev->name, imr);

        /* Enable the IRQ line by setting the bit in the IMR */
        imr = gsc_readl(irq_dev->hpa + OFFSET_IMR);
        imr |= 1 << local_irq;
        gsc_writel(imr, irq_dev->hpa + OFFSET_IMR);
        /*
         * FIXME: read IPR to make sure the IRQ isn't already pending.
         *   If so, we need to read IRR and manually call do_irq().
         */
}

static unsigned int gsc_asic_startup_irq(unsigned int irq)
{
        gsc_asic_enable_irq(irq);
        return 0;
}

static struct irq_chip gsc_asic_interrupt_type = {
        .typename =     "GSC-ASIC",
        .startup =      gsc_asic_startup_irq,
        .shutdown =     gsc_asic_disable_irq,
        .enable =       gsc_asic_enable_irq,
        .disable =      gsc_asic_disable_irq,
        .ack =          no_ack_irq,
        .end =          no_end_irq,
};

int gsc_assign_irq(struct irq_chip *type, void *data)
{
        static int irq = GSC_IRQ_BASE;
        struct irq_desc *desc;

        if (irq > GSC_IRQ_MAX)
                return NO_IRQ;

        desc = irq_to_desc(irq);
        desc->chip = type;
        desc->chip_data = data;
        return irq++;
}

void gsc_asic_assign_irq(struct gsc_asic *asic, int local_irq, int *irqp)
{
        int irq = asic->global_irq[local_irq];
        
        if (irq <= 0) {
                irq = gsc_assign_irq(&gsc_asic_interrupt_type, asic);
                if (irq == NO_IRQ)
                        return;

                asic->global_irq[local_irq] = irq;
        }
        *irqp = irq;
}

struct gsc_fixup_struct {
        void (*choose_irq)(struct parisc_device *, void *);
        void *ctrl;
};

static int gsc_fixup_irqs_callback(struct device *dev, void *data)
{
        struct parisc_device *padev = to_parisc_device(dev);
        struct gsc_fixup_struct *gf = data;

        /* work-around for 715/64 and others which have parent
           at path [5] and children at path [5/0/x] */
        if (padev->id.hw_type == HPHW_FAULTY)
                gsc_fixup_irqs(padev, gf->ctrl, gf->choose_irq);
        gf->choose_irq(padev, gf->ctrl);

        return 0;
}

void gsc_fixup_irqs(struct parisc_device *parent, void *ctrl,
                        void (*choose_irq)(struct parisc_device *, void *))
{
        struct gsc_fixup_struct data = {
                .choose_irq     = choose_irq,
                .ctrl           = ctrl,
        };

        device_for_each_child(&parent->dev, &data, gsc_fixup_irqs_callback);
}

int gsc_common_setup(struct parisc_device *parent, struct gsc_asic *gsc_asic)
{
        struct resource *res;
        int i;

        gsc_asic->gsc = parent;

        /* Initialise local irq -> global irq mapping */
        for (i = 0; i < 32; i++) {
                gsc_asic->global_irq[i] = NO_IRQ;
        }

        /* allocate resource region */
        res = request_mem_region(gsc_asic->hpa, 0x100000, gsc_asic->name);
        if (res) {
                res->flags = IORESOURCE_MEM;    /* do not mark it busy ! */
        }

#if 0
        printk(KERN_WARNING "%s IRQ %d EIM 0x%x", gsc_asic->name,
                        parent->irq, gsc_asic->eim);
        if (gsc_readl(gsc_asic->hpa + OFFSET_IMR))
                printk("  IMR is non-zero! (0x%x)",
                                gsc_readl(gsc_asic->hpa + OFFSET_IMR));
        printk("\n");
#endif

        return 0;
}

extern struct parisc_driver lasi_driver;
extern struct parisc_driver asp_driver;
extern struct parisc_driver wax_driver;

void __init gsc_init(void)
{
#ifdef CONFIG_GSC_LASI
        register_parisc_driver(&lasi_driver);
        register_parisc_driver(&asp_driver);
#endif
#ifdef CONFIG_GSC_WAX
        register_parisc_driver(&wax_driver);
#endif
}