/*
 *  linux/arch/arm/mach-footbridge/irq.c
 *
 *  Copyright (C) 1996-2000 Russell King
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 *  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 <asm/mach/irq.h>

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

static void isa_mask_pic_lo_irq(unsigned int irq)
{
	unsigned int mask = 1 << (irq & 7);

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

static void isa_ack_pic_lo_irq(unsigned int irq)
{
	unsigned int mask = 1 << (irq & 7);

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

static void isa_unmask_pic_lo_irq(unsigned int irq)
{
	unsigned int mask = 1 << (irq & 7);

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

static struct irqchip isa_lo_chip = {
	.ack	= isa_ack_pic_lo_irq,
	.mask	= isa_mask_pic_lo_irq,
	.unmask = isa_unmask_pic_lo_irq,
};

static void isa_mask_pic_hi_irq(unsigned int irq)
{
	unsigned int mask = 1 << (irq & 7);

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

static void isa_ack_pic_hi_irq(unsigned int irq)
{
	unsigned int mask = 1 << (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(unsigned int irq)
{
	unsigned int mask = 1 << (irq & 7);

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

static struct irqchip isa_hi_chip = {
	.ack	= isa_ack_pic_hi_irq,
	.mask	= isa_mask_pic_hi_irq,
	.unmask = isa_unmask_pic_hi_irq,
};

static void
isa_irq_handler(unsigned int irq, struct irqdesc *desc, struct pt_regs *regs)
{
	unsigned int isa_irq = *(unsigned char *)PCIIACK_BASE;

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

	desc = irq_desc + isa_irq;
	desc_handle_irq(isa_irq, desc, regs);
}

static struct irqaction irq_cascade = { .handler = no_action, .name = "cascade", };
static struct resource pic1_resource = { "pic1", 0x20, 0x3f };
static struct resource pic2_resource = { "pic2", 0xa0, 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++) {
			set_irq_chip(irq, &isa_lo_chip);
			set_irq_handler(irq, do_level_IRQ);
			set_irq_flags(irq, IRQF_VALID | IRQF_PROBE);
		}

		for (irq = _ISA_IRQ(8); irq < _ISA_IRQ(16); irq++) {
			set_irq_chip(irq, &isa_hi_chip);
			set_irq_handler(irq, do_level_IRQ);
			set_irq_flags(irq, IRQF_VALID | IRQF_PROBE);
		}

		request_resource(&ioport_resource, &pic1_resource);
		request_resource(&ioport_resource, &pic2_resource);
		setup_irq(IRQ_ISA_CASCADE, &irq_cascade);

		set_irq_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())
			set_irq_flags(_ISA_IRQ(11), IRQF_VALID |
				      IRQF_PROBE | IRQF_NOAUTOEN);
	}
}