// SPDX-License-Identifier: GPL-2.0
/*
 *      linux/arch/alpha/kernel/sys_alcor.c
 *
 *      Copyright (C) 1995 David A Rusling
 *      Copyright (C) 1996 Jay A Estabrook
 *      Copyright (C) 1998, 1999 Richard Henderson
 *
 * Code supporting the ALCOR and XLT (XL-300/366/433).
 */

#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/mm.h>
#include <linux/sched.h>
#include <linux/pci.h>
#include <linux/init.h>
#include <linux/reboot.h>
#include <linux/bitops.h>

#include <asm/ptrace.h>
#include <asm/io.h>
#include <asm/dma.h>
#include <asm/mmu_context.h>
#include <asm/irq.h>
#include <asm/core_cia.h>
#include <asm/tlbflush.h>

#include "proto.h"
#include "irq_impl.h"
#include "pci_impl.h"
#include "machvec_impl.h"


/* Note mask bit is true for ENABLED irqs.  */
static unsigned long cached_irq_mask;

static inline void
alcor_update_irq_hw(unsigned long mask)
{
        *(vuip)GRU_INT_MASK = mask;
        mb();
}

static inline void
alcor_enable_irq(struct irq_data *d)
{
        alcor_update_irq_hw(cached_irq_mask |= 1UL << (d->irq - 16));
}

static void
alcor_disable_irq(struct irq_data *d)
{
        alcor_update_irq_hw(cached_irq_mask &= ~(1UL << (d->irq - 16)));
}

static void
alcor_mask_and_ack_irq(struct irq_data *d)
{
        alcor_disable_irq(d);

        /* On ALCOR/XLT, need to dismiss interrupt via GRU. */
        *(vuip)GRU_INT_CLEAR = 1 << (d->irq - 16); mb();
        *(vuip)GRU_INT_CLEAR = 0; mb();
}

static void
alcor_isa_mask_and_ack_irq(struct irq_data *d)
{
        i8259a_mask_and_ack_irq(d);

        /* On ALCOR/XLT, need to dismiss interrupt via GRU. */
        *(vuip)GRU_INT_CLEAR = 0x80000000; mb();
        *(vuip)GRU_INT_CLEAR = 0; mb();
}

static struct irq_chip alcor_irq_type = {
        .name           = "ALCOR",
        .irq_unmask     = alcor_enable_irq,
        .irq_mask       = alcor_disable_irq,
        .irq_mask_ack   = alcor_mask_and_ack_irq,
};

static void
alcor_device_interrupt(unsigned long vector)
{
        unsigned long pld;
        unsigned int i;

        /* Read the interrupt summary register of the GRU */
        pld = (*(vuip)GRU_INT_REQ) & GRU_INT_REQ_BITS;

        /*
         * Now for every possible bit set, work through them and call
         * the appropriate interrupt handler.
         */
        while (pld) {
                i = ffz(~pld);
                pld &= pld - 1; /* clear least bit set */
                if (i == 31) {
                        isa_device_interrupt(vector);
                } else {
                        handle_irq(16 + i);
                }
        }
}

static void __init
alcor_init_irq(void)
{
        long i;

        if (alpha_using_srm)
                alpha_mv.device_interrupt = srm_device_interrupt;

        *(vuip)GRU_INT_MASK  = 0; mb();                 /* all disabled */
        *(vuip)GRU_INT_EDGE  = 0; mb();                 /* all are level */
        *(vuip)GRU_INT_HILO  = 0x80000000U; mb();       /* ISA only HI */
        *(vuip)GRU_INT_CLEAR = 0; mb();                 /* all clear */

        for (i = 16; i < 48; ++i) {
                /* On Alcor, at least, lines 20..30 are not connected
                   and can generate spurious interrupts if we turn them
                   on while IRQ probing.  */
                if (i >= 16+20 && i <= 16+30)
                        continue;
                irq_set_chip_and_handler(i, &alcor_irq_type, handle_level_irq);
                irq_set_status_flags(i, IRQ_LEVEL);
        }
        i8259a_irq_type.irq_ack = alcor_isa_mask_and_ack_irq;

        init_i8259a_irqs();
        common_init_isa_dma();

        if (request_irq(16 + 31, no_action, 0, "isa-cascade", NULL))
                pr_err("Failed to register isa-cascade interrupt\n");
}


/*
 * PCI Fixup configuration.
 *
 * Summary @ GRU_INT_REQ:
 * Bit      Meaning
 * 0        Interrupt Line A from slot 2
 * 1        Interrupt Line B from slot 2
 * 2        Interrupt Line C from slot 2
 * 3        Interrupt Line D from slot 2
 * 4        Interrupt Line A from slot 1
 * 5        Interrupt line B from slot 1
 * 6        Interrupt Line C from slot 1
 * 7        Interrupt Line D from slot 1
 * 8        Interrupt Line A from slot 0
 * 9        Interrupt Line B from slot 0
 *10        Interrupt Line C from slot 0
 *11        Interrupt Line D from slot 0
 *12        Interrupt Line A from slot 4
 *13        Interrupt Line B from slot 4
 *14        Interrupt Line C from slot 4
 *15        Interrupt Line D from slot 4
 *16        Interrupt Line D from slot 3
 *17        Interrupt Line D from slot 3
 *18        Interrupt Line D from slot 3
 *19        Interrupt Line D from slot 3
 *20-30     Reserved
 *31        EISA interrupt
 *
 * The device to slot mapping looks like:
 *
 * Slot     Device
 *  6       built-in TULIP (XLT only)
 *  7       PCI on board slot 0
 *  8       PCI on board slot 3
 *  9       PCI on board slot 4
 * 10       PCEB (PCI-EISA bridge)
 * 11       PCI on board slot 2
 * 12       PCI on board slot 1
 *   
 *
 * This two layered interrupt approach means that we allocate IRQ 16 and 
 * above for PCI interrupts.  The IRQ relates to which bit the interrupt
 * comes in on.  This makes interrupt processing much easier.
 */

static int
alcor_map_irq(const struct pci_dev *dev, u8 slot, u8 pin)
{
        static char irq_tab[7][5] = {
                /*INT    INTA   INTB   INTC   INTD */
                /* note: IDSEL 17 is XLT only */
                {16+13, 16+13, 16+13, 16+13, 16+13},    /* IdSel 17,  TULIP  */
                { 16+8,  16+8,  16+9, 16+10, 16+11},    /* IdSel 18,  slot 0 */
                {16+16, 16+16, 16+17, 16+18, 16+19},    /* IdSel 19,  slot 3 */
                {16+12, 16+12, 16+13, 16+14, 16+15},    /* IdSel 20,  slot 4 */
                {   -1,    -1,    -1,    -1,    -1},    /* IdSel 21,  PCEB   */
                { 16+0,  16+0,  16+1,  16+2,  16+3},    /* IdSel 22,  slot 2 */
                { 16+4,  16+4,  16+5,  16+6,  16+7},    /* IdSel 23,  slot 1 */
        };
        const long min_idsel = 6, max_idsel = 12, irqs_per_slot = 5;
        return COMMON_TABLE_LOOKUP;
}

static void
alcor_kill_arch(int mode)
{
        cia_kill_arch(mode);

#ifndef ALPHA_RESTORE_SRM_SETUP
        switch(mode) {
        case LINUX_REBOOT_CMD_RESTART:
                /* Who said DEC engineer's have no sense of humor? ;-)  */
                if (alpha_using_srm) {
                        *(vuip) GRU_RESET = 0x0000dead;
                        mb();
                }
                break;
        case LINUX_REBOOT_CMD_HALT:
                break;
        case LINUX_REBOOT_CMD_POWER_OFF:
                break;
        }

        halt();
#endif
}

static void __init
alcor_init_pci(void)
{
        struct pci_dev *dev;

        cia_init_pci();

        /*
         * Now we can look to see if we are really running on an XLT-type
         * motherboard, by looking for a 21040 TULIP in slot 6, which is
         * built into XLT and BRET/MAVERICK, but not available on ALCOR.
         */
        dev = pci_get_device(PCI_VENDOR_ID_DEC,
                              PCI_DEVICE_ID_DEC_TULIP,
                              NULL);
        if (dev && dev->devfn == PCI_DEVFN(6,0)) {
                alpha_mv.sys.cia.gru_int_req_bits = XLT_GRU_INT_REQ_BITS; 
                printk(KERN_INFO "%s: Detected AS500 or XLT motherboard.\n",
                       __func__);
        }
        pci_dev_put(dev);
}


/*
 * The System Vectors
 */

struct alpha_machine_vector alcor_mv __initmv = {
        .vector_name            = "Alcor",
        DO_EV5_MMU,
        DO_DEFAULT_RTC,
        DO_CIA_IO,
        .machine_check          = cia_machine_check,
        .max_isa_dma_address    = ALPHA_ALCOR_MAX_ISA_DMA_ADDRESS,
        .min_io_address         = EISA_DEFAULT_IO_BASE,
        .min_mem_address        = CIA_DEFAULT_MEM_BASE,

        .nr_irqs                = 48,
        .device_interrupt       = alcor_device_interrupt,

        .init_arch              = cia_init_arch,
        .init_irq               = alcor_init_irq,
        .init_rtc               = common_init_rtc,
        .init_pci               = alcor_init_pci,
        .kill_arch              = alcor_kill_arch,
        .pci_map_irq            = alcor_map_irq,
        .pci_swizzle            = common_swizzle,

        .sys = { .cia = {
                .gru_int_req_bits = ALCOR_GRU_INT_REQ_BITS
        }}
};
ALIAS_MV(alcor)

struct alpha_machine_vector xlt_mv __initmv = {
        .vector_name            = "XLT",
        DO_EV5_MMU,
        DO_DEFAULT_RTC,
        DO_CIA_IO,
        .machine_check          = cia_machine_check,
        .max_isa_dma_address    = ALPHA_MAX_ISA_DMA_ADDRESS,
        .min_io_address         = EISA_DEFAULT_IO_BASE,
        .min_mem_address        = CIA_DEFAULT_MEM_BASE,

        .nr_irqs                = 48,
        .device_interrupt       = alcor_device_interrupt,

        .init_arch              = cia_init_arch,
        .init_irq               = alcor_init_irq,
        .init_rtc               = common_init_rtc,
        .init_pci               = alcor_init_pci,
        .kill_arch              = alcor_kill_arch,
        .pci_map_irq            = alcor_map_irq,
        .pci_swizzle            = common_swizzle,

        .sys = { .cia = {
                .gru_int_req_bits = XLT_GRU_INT_REQ_BITS
        }}
};

/* No alpha_mv alias for XLT, since we compile it in unconditionally
   with ALCOR; setup_arch knows how to cope.  */