// SPDX-License-Identifier: GPL-2.0
/*
 * ip22-int.c: Routines for generic manipulation of the INT[23] ASIC
 *             found on INDY and Indigo2 workstations.
 *
 * Copyright (C) 1996 David S. Miller (davem@davemloft.net)
 * Copyright (C) 1997, 1998 Ralf Baechle (ralf@gnu.org)
 * Copyright (C) 1999 Andrew R. Baker (andrewb@uab.edu)
 *                    - Indigo2 changes
 *                    - Interrupt handling fixes
 * Copyright (C) 2001, 2003 Ladislav Michl (ladis@linux-mips.org)
 */
#include <linux/types.h>
#include <linux/init.h>
#include <linux/kernel_stat.h>
#include <linux/interrupt.h>
#include <linux/ftrace.h>

#include <asm/irq_cpu.h>
#include <asm/sgi/hpc3.h>
#include <asm/sgi/ip22.h>

/* So far nothing hangs here */
#undef USE_LIO3_IRQ

struct sgint_regs *sgint;

static char lc0msk_to_irqnr[256];
static char lc1msk_to_irqnr[256];
static char lc2msk_to_irqnr[256];
static char lc3msk_to_irqnr[256];

extern int ip22_eisa_init(void);

static void enable_local0_irq(struct irq_data *d)
{
        /* don't allow mappable interrupt to be enabled from setup_irq,
         * we have our own way to do so */
        if (d->irq != SGI_MAP_0_IRQ)
                sgint->imask0 |= (1 << (d->irq - SGINT_LOCAL0));
}

static void disable_local0_irq(struct irq_data *d)
{
        sgint->imask0 &= ~(1 << (d->irq - SGINT_LOCAL0));
}

static struct irq_chip ip22_local0_irq_type = {
        .name           = "IP22 local 0",
        .irq_mask       = disable_local0_irq,
        .irq_unmask     = enable_local0_irq,
};

static void enable_local1_irq(struct irq_data *d)
{
        /* don't allow mappable interrupt to be enabled from setup_irq,
         * we have our own way to do so */
        if (d->irq != SGI_MAP_1_IRQ)
                sgint->imask1 |= (1 << (d->irq - SGINT_LOCAL1));
}

static void disable_local1_irq(struct irq_data *d)
{
        sgint->imask1 &= ~(1 << (d->irq - SGINT_LOCAL1));
}

static struct irq_chip ip22_local1_irq_type = {
        .name           = "IP22 local 1",
        .irq_mask       = disable_local1_irq,
        .irq_unmask     = enable_local1_irq,
};

static void enable_local2_irq(struct irq_data *d)
{
        sgint->imask0 |= (1 << (SGI_MAP_0_IRQ - SGINT_LOCAL0));
        sgint->cmeimask0 |= (1 << (d->irq - SGINT_LOCAL2));
}

static void disable_local2_irq(struct irq_data *d)
{
        sgint->cmeimask0 &= ~(1 << (d->irq - SGINT_LOCAL2));
        if (!sgint->cmeimask0)
                sgint->imask0 &= ~(1 << (SGI_MAP_0_IRQ - SGINT_LOCAL0));
}

static struct irq_chip ip22_local2_irq_type = {
        .name           = "IP22 local 2",
        .irq_mask       = disable_local2_irq,
        .irq_unmask     = enable_local2_irq,
};

static void enable_local3_irq(struct irq_data *d)
{
        sgint->imask1 |= (1 << (SGI_MAP_1_IRQ - SGINT_LOCAL1));
        sgint->cmeimask1 |= (1 << (d->irq - SGINT_LOCAL3));
}

static void disable_local3_irq(struct irq_data *d)
{
        sgint->cmeimask1 &= ~(1 << (d->irq - SGINT_LOCAL3));
        if (!sgint->cmeimask1)
                sgint->imask1 &= ~(1 << (SGI_MAP_1_IRQ - SGINT_LOCAL1));
}

static struct irq_chip ip22_local3_irq_type = {
        .name           = "IP22 local 3",
        .irq_mask       = disable_local3_irq,
        .irq_unmask     = enable_local3_irq,
};

static void indy_local0_irqdispatch(void)
{
        u8 mask = sgint->istat0 & sgint->imask0;
        u8 mask2;
        int irq;

        if (mask & SGINT_ISTAT0_LIO2) {
                mask2 = sgint->vmeistat & sgint->cmeimask0;
                irq = lc2msk_to_irqnr[mask2];
        } else
                irq = lc0msk_to_irqnr[mask];

        /*
         * workaround for INT2 bug; if irq == 0, INT2 has seen a fifo full
         * irq, but failed to latch it into status register
         */
        if (irq)
                do_IRQ(irq);
        else
                do_IRQ(SGINT_LOCAL0 + 0);
}

static void indy_local1_irqdispatch(void)
{
        u8 mask = sgint->istat1 & sgint->imask1;
        u8 mask2;
        int irq;

        if (mask & SGINT_ISTAT1_LIO3) {
                mask2 = sgint->vmeistat & sgint->cmeimask1;
                irq = lc3msk_to_irqnr[mask2];
        } else
                irq = lc1msk_to_irqnr[mask];

        /* if irq == 0, then the interrupt has already been cleared */
        if (irq)
                do_IRQ(irq);
}

extern void ip22_be_interrupt(int irq);

static void __irq_entry indy_buserror_irq(void)
{
        int irq = SGI_BUSERR_IRQ;

        irq_enter();
        kstat_incr_irq_this_cpu(irq);
        ip22_be_interrupt(irq);
        irq_exit();
}

#ifdef USE_LIO3_IRQ
#define SGI_INTERRUPTS  SGINT_END
#else
#define SGI_INTERRUPTS  SGINT_LOCAL3
#endif

/*
 * IRQs on the INDY look basically (barring software IRQs which we don't use
 * at all) like:
 *
 *      MIPS IRQ        Source
 *      --------        ------
 *             0        Software (ignored)
 *             1        Software (ignored)
 *             2        Local IRQ level zero
 *             3        Local IRQ level one
 *             4        8254 Timer zero
 *             5        8254 Timer one
 *             6        Bus Error
 *             7        R4k timer (what we use)
 *
 * We handle the IRQ according to _our_ priority which is:
 *
 * Highest ----     R4k Timer
 *                  Local IRQ zero
 *                  Local IRQ one
 *                  Bus Error
 *                  8254 Timer zero
 * Lowest  ----     8254 Timer one
 *
 * then we just return, if multiple IRQs are pending then we will just take
 * another exception, big deal.
 */

asmlinkage void plat_irq_dispatch(void)
{
        unsigned int pending = read_c0_status() & read_c0_cause();

        /*
         * First we check for r4k counter/timer IRQ.
         */
        if (pending & CAUSEF_IP7)
                do_IRQ(SGI_TIMER_IRQ);
        else if (pending & CAUSEF_IP2)
                indy_local0_irqdispatch();
        else if (pending & CAUSEF_IP3)
                indy_local1_irqdispatch();
        else if (pending & CAUSEF_IP6)
                indy_buserror_irq();
        else if (pending & (CAUSEF_IP4 | CAUSEF_IP5))
                indy_8254timer_irq();
}

void __init arch_init_irq(void)
{
        int i;

        /* Init local mask --> irq tables. */
        for (i = 0; i < 256; i++) {
                if (i & 0x80) {
                        lc0msk_to_irqnr[i] = SGINT_LOCAL0 + 7;
                        lc1msk_to_irqnr[i] = SGINT_LOCAL1 + 7;
                        lc2msk_to_irqnr[i] = SGINT_LOCAL2 + 7;
                        lc3msk_to_irqnr[i] = SGINT_LOCAL3 + 7;
                } else if (i & 0x40) {
                        lc0msk_to_irqnr[i] = SGINT_LOCAL0 + 6;
                        lc1msk_to_irqnr[i] = SGINT_LOCAL1 + 6;
                        lc2msk_to_irqnr[i] = SGINT_LOCAL2 + 6;
                        lc3msk_to_irqnr[i] = SGINT_LOCAL3 + 6;
                } else if (i & 0x20) {
                        lc0msk_to_irqnr[i] = SGINT_LOCAL0 + 5;
                        lc1msk_to_irqnr[i] = SGINT_LOCAL1 + 5;
                        lc2msk_to_irqnr[i] = SGINT_LOCAL2 + 5;
                        lc3msk_to_irqnr[i] = SGINT_LOCAL3 + 5;
                } else if (i & 0x10) {
                        lc0msk_to_irqnr[i] = SGINT_LOCAL0 + 4;
                        lc1msk_to_irqnr[i] = SGINT_LOCAL1 + 4;
                        lc2msk_to_irqnr[i] = SGINT_LOCAL2 + 4;
                        lc3msk_to_irqnr[i] = SGINT_LOCAL3 + 4;
                } else if (i & 0x08) {
                        lc0msk_to_irqnr[i] = SGINT_LOCAL0 + 3;
                        lc1msk_to_irqnr[i] = SGINT_LOCAL1 + 3;
                        lc2msk_to_irqnr[i] = SGINT_LOCAL2 + 3;
                        lc3msk_to_irqnr[i] = SGINT_LOCAL3 + 3;
                } else if (i & 0x04) {
                        lc0msk_to_irqnr[i] = SGINT_LOCAL0 + 2;
                        lc1msk_to_irqnr[i] = SGINT_LOCAL1 + 2;
                        lc2msk_to_irqnr[i] = SGINT_LOCAL2 + 2;
                        lc3msk_to_irqnr[i] = SGINT_LOCAL3 + 2;
                } else if (i & 0x02) {
                        lc0msk_to_irqnr[i] = SGINT_LOCAL0 + 1;
                        lc1msk_to_irqnr[i] = SGINT_LOCAL1 + 1;
                        lc2msk_to_irqnr[i] = SGINT_LOCAL2 + 1;
                        lc3msk_to_irqnr[i] = SGINT_LOCAL3 + 1;
                } else if (i & 0x01) {
                        lc0msk_to_irqnr[i] = SGINT_LOCAL0 + 0;
                        lc1msk_to_irqnr[i] = SGINT_LOCAL1 + 0;
                        lc2msk_to_irqnr[i] = SGINT_LOCAL2 + 0;
                        lc3msk_to_irqnr[i] = SGINT_LOCAL3 + 0;
                } else {
                        lc0msk_to_irqnr[i] = 0;
                        lc1msk_to_irqnr[i] = 0;
                        lc2msk_to_irqnr[i] = 0;
                        lc3msk_to_irqnr[i] = 0;
                }
        }

        /* Mask out all interrupts. */
        sgint->imask0 = 0;
        sgint->imask1 = 0;
        sgint->cmeimask0 = 0;
        sgint->cmeimask1 = 0;

        /* init CPU irqs */
        mips_cpu_irq_init();

        for (i = SGINT_LOCAL0; i < SGI_INTERRUPTS; i++) {
                struct irq_chip *handler;

                if (i < SGINT_LOCAL1)
                        handler         = &ip22_local0_irq_type;
                else if (i < SGINT_LOCAL2)
                        handler         = &ip22_local1_irq_type;
                else if (i < SGINT_LOCAL3)
                        handler         = &ip22_local2_irq_type;
                else
                        handler         = &ip22_local3_irq_type;

                irq_set_chip_and_handler(i, handler, handle_level_irq);
        }

        /* vector handler. this register the IRQ as non-sharable */
        if (request_irq(SGI_LOCAL_0_IRQ, no_action, IRQF_NO_THREAD,
                        "local0 cascade", NULL))
                pr_err("Failed to register local0 cascade interrupt\n");
        if (request_irq(SGI_LOCAL_1_IRQ, no_action, IRQF_NO_THREAD,
                        "local1 cascade", NULL))
                pr_err("Failed to register local1 cascade interrupt\n");
        if (request_irq(SGI_BUSERR_IRQ, no_action, IRQF_NO_THREAD,
                        "Bus Error", NULL))
                pr_err("Failed to register Bus Error interrupt\n");

        /* cascade in cascade. i love Indy ;-) */
        if (request_irq(SGI_MAP_0_IRQ, no_action, IRQF_NO_THREAD,
                        "mapable0 cascade", NULL))
                pr_err("Failed to register mapable0 cascade interrupt\n");
#ifdef USE_LIO3_IRQ
        if (request_irq(SGI_MAP_1_IRQ, no_action, IRQF_NO_THREAD,
                        "mapable1 cascade", NULL))
                pr_err("Failed to register mapable1 cascade interrupt\n");
#endif

#ifdef CONFIG_EISA
        if (ip22_is_fullhouse())        /* Only Indigo-2 has EISA stuff */
                ip22_eisa_init();
#endif
}