// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Copyright (C) 2008 Freescale Semiconductor, Inc. All rights reserved.
 *
 * Author: John Rigby, <jrigby@freescale.com>
 *
 * Description:
 * MPC5121ADS CPLD irq handling
 */

#undef DEBUG

#include <linux/kernel.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/io.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>

#include "mpc5121_ads.h"

static struct device_node *cpld_pic_node;
static struct irq_domain *cpld_pic_host;

/*
 * Bits to ignore in the misc_status register
 * 0x10 touch screen pendown is hard routed to irq1
 * 0x02 pci status is read from pci status register
 */
#define MISC_IGNORE 0x12

/*
 * Nothing to ignore in pci status register
 */
#define PCI_IGNORE 0x00

struct cpld_pic {
        u8 pci_mask;
        u8 pci_status;
        u8 route;
        u8 misc_mask;
        u8 misc_status;
        u8 misc_control;
};

static struct cpld_pic __iomem *cpld_regs;

static void __iomem *
irq_to_pic_mask(unsigned int irq)
{
        return irq <= 7 ? &cpld_regs->pci_mask : &cpld_regs->misc_mask;
}

static unsigned int
irq_to_pic_bit(unsigned int irq)
{
        return 1 << (irq & 0x7);
}

static void
cpld_mask_irq(struct irq_data *d)
{
        unsigned int cpld_irq = (unsigned int)irqd_to_hwirq(d);
        void __iomem *pic_mask = irq_to_pic_mask(cpld_irq);

        out_8(pic_mask,
              in_8(pic_mask) | irq_to_pic_bit(cpld_irq));
}

static void
cpld_unmask_irq(struct irq_data *d)
{
        unsigned int cpld_irq = (unsigned int)irqd_to_hwirq(d);
        void __iomem *pic_mask = irq_to_pic_mask(cpld_irq);

        out_8(pic_mask,
              in_8(pic_mask) & ~irq_to_pic_bit(cpld_irq));
}

static struct irq_chip cpld_pic = {
        .name = "CPLD PIC",
        .irq_mask = cpld_mask_irq,
        .irq_ack = cpld_mask_irq,
        .irq_unmask = cpld_unmask_irq,
};

static unsigned int
cpld_pic_get_irq(int offset, u8 ignore, u8 __iomem *statusp,
                            u8 __iomem *maskp)
{
        u8 status = in_8(statusp);
        u8 mask = in_8(maskp);

        /* ignore don't cares and masked irqs */
        status |= (ignore | mask);

        if (status == 0xff)
                return ~0;

        return ffz(status) + offset;
}

static void cpld_pic_cascade(struct irq_desc *desc)
{
        unsigned int hwirq;

        hwirq = cpld_pic_get_irq(0, PCI_IGNORE, &cpld_regs->pci_status,
                &cpld_regs->pci_mask);
        if (hwirq != ~0) {
                generic_handle_domain_irq(cpld_pic_host, hwirq);
                return;
        }

        hwirq = cpld_pic_get_irq(8, MISC_IGNORE, &cpld_regs->misc_status,
                &cpld_regs->misc_mask);
        if (hwirq != ~0) {
                generic_handle_domain_irq(cpld_pic_host, hwirq);
                return;
        }
}

static int
cpld_pic_host_match(struct irq_domain *h, struct device_node *node,
                    enum irq_domain_bus_token bus_token)
{
        return cpld_pic_node == node;
}

static int
cpld_pic_host_map(struct irq_domain *h, unsigned int virq,
                             irq_hw_number_t hw)
{
        irq_set_status_flags(virq, IRQ_LEVEL);
        irq_set_chip_and_handler(virq, &cpld_pic, handle_level_irq);
        return 0;
}

static const struct irq_domain_ops cpld_pic_host_ops = {
        .match = cpld_pic_host_match,
        .map = cpld_pic_host_map,
};

void __init
mpc5121_ads_cpld_map(void)
{
        struct device_node *np = NULL;

        np = of_find_compatible_node(NULL, NULL, "fsl,mpc5121ads-cpld-pic");
        if (!np) {
                printk(KERN_ERR "CPLD PIC init: can not find cpld-pic node\n");
                return;
        }

        cpld_regs = of_iomap(np, 0);
        of_node_put(np);
}

void __init
mpc5121_ads_cpld_pic_init(void)
{
        unsigned int cascade_irq;
        struct device_node *np = NULL;

        pr_debug("cpld_ic_init\n");

        np = of_find_compatible_node(NULL, NULL, "fsl,mpc5121ads-cpld-pic");
        if (!np) {
                printk(KERN_ERR "CPLD PIC init: can not find cpld-pic node\n");
                return;
        }

        if (!cpld_regs)
                goto end;

        cascade_irq = irq_of_parse_and_map(np, 0);
        if (!cascade_irq)
                goto end;

        /*
         * statically route touch screen pendown through 1
         * and ignore it here
         * route all others through our cascade irq
         */
        out_8(&cpld_regs->route, 0xfd);
        out_8(&cpld_regs->pci_mask, 0xff);
        /* unmask pci ints in misc mask */
        out_8(&cpld_regs->misc_mask, ~(MISC_IGNORE));

        cpld_pic_node = of_node_get(np);

        cpld_pic_host = irq_domain_create_linear(of_fwnode_handle(np), 16,
                                                 &cpld_pic_host_ops, NULL);
        if (!cpld_pic_host) {
                printk(KERN_ERR "CPLD PIC: failed to allocate irq host!\n");
                goto end;
        }

        irq_set_chained_handler(cascade_irq, cpld_pic_cascade);
end:
        of_node_put(np);
}