// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Driver for MIPS Goldfish Programmable Interrupt Controller.
 *
 * Author: Miodrag Dinic <miodrag.dinic@mips.com>
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/irqchip.h>
#include <linux/irqchip/chained_irq.h>
#include <linux/irqdomain.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>

#define GFPIC_NR_IRQS                   32

/* 8..39 Cascaded Goldfish PIC interrupts */
#define GFPIC_IRQ_BASE                  8

#define GFPIC_REG_IRQ_PENDING           0x04
#define GFPIC_REG_IRQ_DISABLE_ALL       0x08
#define GFPIC_REG_IRQ_DISABLE           0x0c
#define GFPIC_REG_IRQ_ENABLE            0x10

struct goldfish_pic_data {
        void __iomem *base;
        struct irq_domain *irq_domain;
};

static void goldfish_pic_cascade(struct irq_desc *desc)
{
        struct goldfish_pic_data *gfpic = irq_desc_get_handler_data(desc);
        struct irq_chip *host_chip = irq_desc_get_chip(desc);
        u32 pending, hwirq;

        chained_irq_enter(host_chip, desc);

        pending = readl(gfpic->base + GFPIC_REG_IRQ_PENDING);
        while (pending) {
                hwirq = __fls(pending);
                generic_handle_domain_irq(gfpic->irq_domain, hwirq);
                pending &= ~(1 << hwirq);
        }

        chained_irq_exit(host_chip, desc);
}

static const struct irq_domain_ops goldfish_irq_domain_ops = {
        .xlate = irq_domain_xlate_onecell,
};

static int __init goldfish_pic_of_init(struct device_node *of_node,
                                       struct device_node *parent)
{
        struct goldfish_pic_data *gfpic;
        struct irq_chip_generic *gc;
        struct irq_chip_type *ct;
        unsigned int parent_irq;
        int ret = 0;

        gfpic = kzalloc_obj(*gfpic);
        if (!gfpic) {
                ret = -ENOMEM;
                goto out_err;
        }

        parent_irq = irq_of_parse_and_map(of_node, 0);
        if (!parent_irq) {
                pr_err("Failed to map parent IRQ!\n");
                ret = -EINVAL;
                goto out_free;
        }

        gfpic->base = of_iomap(of_node, 0);
        if (!gfpic->base) {
                pr_err("Failed to map base address!\n");
                ret = -ENOMEM;
                goto out_unmap_irq;
        }

        /* Mask interrupts. */
        writel(1, gfpic->base + GFPIC_REG_IRQ_DISABLE_ALL);

        gc = irq_alloc_generic_chip("GFPIC", 1, GFPIC_IRQ_BASE, gfpic->base,
                                    handle_level_irq);
        if (!gc) {
                pr_err("Failed to allocate chip structures!\n");
                ret = -ENOMEM;
                goto out_iounmap;
        }

        ct = gc->chip_types;
        ct->regs.enable = GFPIC_REG_IRQ_ENABLE;
        ct->regs.disable = GFPIC_REG_IRQ_DISABLE;
        ct->chip.irq_unmask = irq_gc_unmask_enable_reg;
        ct->chip.irq_mask = irq_gc_mask_disable_reg;

        irq_setup_generic_chip(gc, IRQ_MSK(GFPIC_NR_IRQS), 0,
                               IRQ_NOPROBE | IRQ_LEVEL, 0);

        gfpic->irq_domain = irq_domain_create_legacy(of_fwnode_handle(of_node), GFPIC_NR_IRQS,
                                                     GFPIC_IRQ_BASE, 0, &goldfish_irq_domain_ops,
                                                     NULL);
        if (!gfpic->irq_domain) {
                pr_err("Failed to add irqdomain!\n");
                ret = -ENOMEM;
                goto out_destroy_generic_chip;
        }

        irq_set_chained_handler_and_data(parent_irq,
                                         goldfish_pic_cascade, gfpic);

        pr_info("Successfully registered.\n");
        return 0;

out_destroy_generic_chip:
        irq_destroy_generic_chip(gc, IRQ_MSK(GFPIC_NR_IRQS),
                                 IRQ_NOPROBE | IRQ_LEVEL, 0);
out_iounmap:
        iounmap(gfpic->base);
out_unmap_irq:
        irq_dispose_mapping(parent_irq);
out_free:
        kfree(gfpic);
out_err:
        pr_err("Failed to initialize! (errno = %d)\n", ret);
        return ret;
}

IRQCHIP_DECLARE(google_gf_pic, "google,goldfish-pic", goldfish_pic_of_init);