root/arch/arm/mach-rpc/irq.c
// SPDX-License-Identifier: GPL-2.0
#include <linux/init.h>
#include <linux/list.h>
#include <linux/io.h>

#include <asm/mach/irq.h>
#include <asm/hardware/iomd.h>
#include <asm/irq.h>
#include <asm/fiq.h>

// These are offsets from the stat register for each IRQ bank
#define STAT    0x00
#define REQ     0x04
#define CLR     0x04
#define MASK    0x08

static const u8 irq_prio_h[256] = {
         0, 8, 9, 8,10,10,10,10,11,11,11,11,10,10,10,10,
        12, 8, 9, 8,10,10,10,10,11,11,11,11,10,10,10,10,
        13,13,13,13,10,10,10,10,11,11,11,11,10,10,10,10,
        13,13,13,13,10,10,10,10,11,11,11,11,10,10,10,10,
        14,14,14,14,10,10,10,10,11,11,11,11,10,10,10,10,
        14,14,14,14,10,10,10,10,11,11,11,11,10,10,10,10,
        13,13,13,13,10,10,10,10,11,11,11,11,10,10,10,10,
        13,13,13,13,10,10,10,10,11,11,11,11,10,10,10,10,
        15,15,15,15,10,10,10,10,11,11,11,11,10,10,10,10,
        15,15,15,15,10,10,10,10,11,11,11,11,10,10,10,10,
        13,13,13,13,10,10,10,10,11,11,11,11,10,10,10,10,
        13,13,13,13,10,10,10,10,11,11,11,11,10,10,10,10,
        15,15,15,15,10,10,10,10,11,11,11,11,10,10,10,10,
        15,15,15,15,10,10,10,10,11,11,11,11,10,10,10,10,
        13,13,13,13,10,10,10,10,11,11,11,11,10,10,10,10,
        13,13,13,13,10,10,10,10,11,11,11,11,10,10,10,10,
};

static const u8 irq_prio_d[256] = {
         0,16,17,16,18,16,17,16,19,16,17,16,18,16,17,16,
        20,16,17,16,18,16,17,16,19,16,17,16,18,16,17,16,
        21,16,17,16,18,16,17,16,19,16,17,16,18,16,17,16,
        21,16,17,16,18,16,17,16,19,16,17,16,18,16,17,16,
        22,16,17,16,18,16,17,16,19,16,17,16,18,16,17,16,
        22,16,17,16,18,16,17,16,19,16,17,16,18,16,17,16,
        21,16,17,16,18,16,17,16,19,16,17,16,18,16,17,16,
        21,16,17,16,18,16,17,16,19,16,17,16,18,16,17,16,
        23,16,17,16,18,16,17,16,19,16,17,16,18,16,17,16,
        23,16,17,16,18,16,17,16,19,16,17,16,18,16,17,16,
        21,16,17,16,18,16,17,16,19,16,17,16,18,16,17,16,
        21,16,17,16,18,16,17,16,19,16,17,16,18,16,17,16,
        22,16,17,16,18,16,17,16,19,16,17,16,18,16,17,16,
        22,16,17,16,18,16,17,16,19,16,17,16,18,16,17,16,
        21,16,17,16,18,16,17,16,19,16,17,16,18,16,17,16,
        21,16,17,16,18,16,17,16,19,16,17,16,18,16,17,16,
};

static const u8 irq_prio_l[256] = {
         0, 0, 1, 0, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3,
         4, 0, 1, 0, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3,
         5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
         5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
         6, 6, 6, 6, 6, 6, 6, 6, 3, 3, 3, 3, 3, 3, 3, 3,
         6, 6, 6, 6, 6, 6, 6, 6, 3, 3, 3, 3, 3, 3, 3, 3,
         5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
         5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
         7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
         7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
         7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
         7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
         7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
         7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
         7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
         7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
};

static int iomd_get_irq_nr(void)
{
        int irq;
        u8 reg;

        /* get highest priority first */
        reg = readb(IOC_BASE + IOMD_IRQREQB);
        irq = irq_prio_h[reg];
        if (irq)
                return irq;

        /* get DMA  */
        reg = readb(IOC_BASE + IOMD_DMAREQ);
        irq = irq_prio_d[reg];
        if (irq)
                return irq;

        /* get low priority */
        reg = readb(IOC_BASE + IOMD_IRQREQA);
        irq = irq_prio_l[reg];
        if (irq)
                return irq;
        return 0;
}

static void iomd_handle_irq(struct pt_regs *regs)
{
        int irq;

        do {
                irq = iomd_get_irq_nr();
                if (irq)
                        generic_handle_irq(irq);
        } while (irq);
}

static void __iomem *iomd_get_base(struct irq_data *d)
{
        void *cd = irq_data_get_irq_chip_data(d);

        return (void __iomem *)(unsigned long)cd;
}

static void iomd_set_base_mask(unsigned int irq, void __iomem *base, u32 mask)
{
        struct irq_data *d = irq_get_irq_data(irq);

        d->mask = mask;
        irq_set_chip_data(irq, (void *)(unsigned long)base);
}

static void iomd_irq_mask_ack(struct irq_data *d)
{
        void __iomem *base = iomd_get_base(d);
        unsigned int val, mask = d->mask;

        val = readb(base + MASK);
        writeb(val & ~mask, base + MASK);
        writeb(mask, base + CLR);
}

static void iomd_irq_mask(struct irq_data *d)
{
        void __iomem *base = iomd_get_base(d);
        unsigned int val, mask = d->mask;

        val = readb(base + MASK);
        writeb(val & ~mask, base + MASK);
}

static void iomd_irq_unmask(struct irq_data *d)
{
        void __iomem *base = iomd_get_base(d);
        unsigned int val, mask = d->mask;

        val = readb(base + MASK);
        writeb(val | mask, base + MASK);
}

static struct irq_chip iomd_chip_clr = {
        .irq_mask_ack   = iomd_irq_mask_ack,
        .irq_mask       = iomd_irq_mask,
        .irq_unmask     = iomd_irq_unmask,
};

static struct irq_chip iomd_chip_noclr = {
        .irq_mask       = iomd_irq_mask,
        .irq_unmask     = iomd_irq_unmask,
};

extern unsigned char rpc_default_fiq_start, rpc_default_fiq_end;

void __init rpc_init_irq(void)
{
        unsigned int irq, clr, set;

        iomd_writeb(0, IOMD_IRQMASKA);
        iomd_writeb(0, IOMD_IRQMASKB);
        iomd_writeb(0, IOMD_FIQMASK);
        iomd_writeb(0, IOMD_DMAMASK);

        set_fiq_handler(&rpc_default_fiq_start,
                &rpc_default_fiq_end - &rpc_default_fiq_start);

        set_handle_irq(iomd_handle_irq);

        for (irq = 0; irq < NR_IRQS; irq++) {
                clr = IRQ_NOREQUEST;
                set = 0;

                if (irq <= 6 || (irq >= 9 && irq <= 15))
                        clr |= IRQ_NOPROBE;

                if (irq == 21 || (irq >= 16 && irq <= 19) ||
                    irq == IRQ_KEYBOARDTX)
                        set |= IRQ_NOAUTOEN;

                switch (irq) {
                case 0 ... 7:
                        irq_set_chip_and_handler(irq, &iomd_chip_clr,
                                                 handle_level_irq);
                        irq_modify_status(irq, clr, set);
                        iomd_set_base_mask(irq, IOMD_BASE + IOMD_IRQSTATA,
                                           BIT(irq));
                        break;

                case 8 ... 15:
                        irq_set_chip_and_handler(irq, &iomd_chip_noclr,
                                                 handle_level_irq);
                        irq_modify_status(irq, clr, set);
                        iomd_set_base_mask(irq, IOMD_BASE + IOMD_IRQSTATB,
                                           BIT(irq - 8));
                        break;

                case 16 ... 21:
                        irq_set_chip_and_handler(irq, &iomd_chip_noclr,
                                                 handle_level_irq);
                        irq_modify_status(irq, clr, set);
                        iomd_set_base_mask(irq, IOMD_BASE + IOMD_DMASTAT,
                                           BIT(irq - 16));
                        break;

                case 64 ... 71:
                        irq_set_chip(irq, &iomd_chip_noclr);
                        irq_modify_status(irq, clr, set);
                        iomd_set_base_mask(irq, IOMD_BASE + IOMD_FIQSTAT,
                                           BIT(irq - 64));
                        break;
                }
        }

        init_FIQ(FIQ_START);
}