// SPDX-License-Identifier: GPL-2.0-only
/*
 *  linux/arch/arm/mach-footbridge/irq.c
 *
 *  Copyright (C) 1996-2000 Russell King
 *
 *  Changelog:
 *   22-Aug-1998 RMK    Restructured IRQ routines
 *   03-Sep-1998 PJB    Merged CATS support
 *   20-Jan-1998 RMK    Started merge of EBSA286, CATS and NetWinder
 *   26-Jan-1999 PJB    Don't use IACK on CATS
 *   16-Mar-1999 RMK    Added autodetect of ISA PICs
 */
#include <linux/ioport.h>
#include <linux/interrupt.h>
#include <linux/list.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/spinlock.h>

#include <asm/mach/irq.h>

#include <mach/hardware.h>
#include <asm/hardware/dec21285.h>
#include <asm/irq.h>
#include <asm/mach-types.h>

#include "common.h"

static void isa_mask_pic_lo_irq(struct irq_data *d)
{
        unsigned int mask = 1 << (d->irq & 7);

        outb(inb(PIC_MASK_LO) | mask, PIC_MASK_LO);
}

static void isa_ack_pic_lo_irq(struct irq_data *d)
{
        unsigned int mask = 1 << (d->irq & 7);

        outb(inb(PIC_MASK_LO) | mask, PIC_MASK_LO);
        outb(0x20, PIC_LO);
}

static void isa_unmask_pic_lo_irq(struct irq_data *d)
{
        unsigned int mask = 1 << (d->irq & 7);

        outb(inb(PIC_MASK_LO) & ~mask, PIC_MASK_LO);
}

static struct irq_chip isa_lo_chip = {
        .irq_ack        = isa_ack_pic_lo_irq,
        .irq_mask       = isa_mask_pic_lo_irq,
        .irq_unmask     = isa_unmask_pic_lo_irq,
};

static void isa_mask_pic_hi_irq(struct irq_data *d)
{
        unsigned int mask = 1 << (d->irq & 7);

        outb(inb(PIC_MASK_HI) | mask, PIC_MASK_HI);
}

static void isa_ack_pic_hi_irq(struct irq_data *d)
{
        unsigned int mask = 1 << (d->irq & 7);

        outb(inb(PIC_MASK_HI) | mask, PIC_MASK_HI);
        outb(0x62, PIC_LO);
        outb(0x20, PIC_HI);
}

static void isa_unmask_pic_hi_irq(struct irq_data *d)
{
        unsigned int mask = 1 << (d->irq & 7);

        outb(inb(PIC_MASK_HI) & ~mask, PIC_MASK_HI);
}

static struct irq_chip isa_hi_chip = {
        .irq_ack        = isa_ack_pic_hi_irq,
        .irq_mask       = isa_mask_pic_hi_irq,
        .irq_unmask     = isa_unmask_pic_hi_irq,
};

static void isa_irq_handler(struct irq_desc *desc)
{
        unsigned int isa_irq = *(unsigned char *)PCIIACK_BASE;

        if (isa_irq < _ISA_IRQ(0) || isa_irq >= _ISA_IRQ(16)) {
                do_bad_IRQ(desc);
                return;
        }

        generic_handle_irq(isa_irq);
}

static struct resource pic1_resource = {
        .name   = "pic1",
        .start  = 0x20,
        .end    = 0x3f,
};

static struct resource pic2_resource = {
        .name   = "pic2",
        .start  = 0xa0,
        .end    = 0xbf,
};

void __init isa_init_irq(unsigned int host_irq)
{
        unsigned int irq;

        /*
         * Setup, and then probe for an ISA PIC
         * If the PIC is not there, then we
         * ignore the PIC.
         */
        outb(0x11, PIC_LO);
        outb(_ISA_IRQ(0), PIC_MASK_LO); /* IRQ number           */
        outb(0x04, PIC_MASK_LO);        /* Slave on Ch2         */
        outb(0x01, PIC_MASK_LO);        /* x86                  */
        outb(0xf5, PIC_MASK_LO);        /* pattern: 11110101    */

        outb(0x11, PIC_HI);
        outb(_ISA_IRQ(8), PIC_MASK_HI); /* IRQ number           */
        outb(0x02, PIC_MASK_HI);        /* Slave on Ch1         */
        outb(0x01, PIC_MASK_HI);        /* x86                  */
        outb(0xfa, PIC_MASK_HI);        /* pattern: 11111010    */

        outb(0x0b, PIC_LO);
        outb(0x0b, PIC_HI);

        if (inb(PIC_MASK_LO) == 0xf5 && inb(PIC_MASK_HI) == 0xfa) {
                outb(0xff, PIC_MASK_LO);/* mask all IRQs        */
                outb(0xff, PIC_MASK_HI);/* mask all IRQs        */
        } else {
                printk(KERN_INFO "IRQ: ISA PIC not found\n");
                host_irq = (unsigned int)-1;
        }

        if (host_irq != (unsigned int)-1) {
                for (irq = _ISA_IRQ(0); irq < _ISA_IRQ(8); irq++) {
                        irq_set_chip_and_handler(irq, &isa_lo_chip,
                                                 handle_level_irq);
                        irq_clear_status_flags(irq, IRQ_NOREQUEST | IRQ_NOPROBE);
                }

                for (irq = _ISA_IRQ(8); irq < _ISA_IRQ(16); irq++) {
                        irq_set_chip_and_handler(irq, &isa_hi_chip,
                                                 handle_level_irq);
                        irq_clear_status_flags(irq, IRQ_NOREQUEST | IRQ_NOPROBE);
                }

                request_resource(&ioport_resource, &pic1_resource);
                request_resource(&ioport_resource, &pic2_resource);

                irq = IRQ_ISA_CASCADE;
                if (request_irq(irq, no_action, 0, "cascade", NULL))
                        pr_err("Failed to request irq %u (cascade)\n", irq);

                irq_set_chained_handler(host_irq, isa_irq_handler);

                /*
                 * On the NetWinder, don't automatically
                 * enable ISA IRQ11 when it is requested.
                 * There appears to be a missing pull-up
                 * resistor on this line.
                 */
                if (machine_is_netwinder())
                        irq_modify_status(_ISA_IRQ(11),
                                IRQ_NOREQUEST | IRQ_NOPROBE, IRQ_NOAUTOEN);
        }
}