/*
 * Conexant Digicolor SoCs IRQ chip driver
 *
 * Author: Baruch Siach <baruch@tkos.co.il>
 *
 * Copyright (C) 2014 Paradox Innovation Ltd.
 *
 * This file is licensed under the terms of the GNU General Public
 * License version 2.  This program is licensed "as is" without any
 * warranty of any kind, whether express or implied.
 */

#include <linux/io.h>
#include <linux/irq.h>
#include <linux/irqchip.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <linux/mfd/syscon.h>
#include <linux/regmap.h>

#include <asm/exception.h>

#define UC_IRQ_CONTROL          0x04

#define IC_FLAG_CLEAR_LO        0x00
#define IC_FLAG_CLEAR_XLO       0x04
#define IC_INT0ENABLE_LO        0x10
#define IC_INT0ENABLE_XLO       0x14
#define IC_INT0STATUS_LO        0x18
#define IC_INT0STATUS_XLO       0x1c

static struct irq_domain *digicolor_irq_domain;

static void __exception_irq_entry digicolor_handle_irq(struct pt_regs *regs)
{
        struct irq_domain_chip_generic *dgc = digicolor_irq_domain->gc;
        struct irq_chip_generic *gc = dgc->gc[0];
        u32 status, hwirq;

        do {
                status = irq_reg_readl(gc, IC_INT0STATUS_LO);
                if (status) {
                        hwirq = ffs(status) - 1;
                } else {
                        status = irq_reg_readl(gc, IC_INT0STATUS_XLO);
                        if (status)
                                hwirq = ffs(status) - 1 + 32;
                        else
                                return;
                }

                generic_handle_domain_irq(digicolor_irq_domain, hwirq);
        } while (1);
}

static void __init digicolor_set_gc(void __iomem *reg_base, unsigned irq_base,
                                    unsigned en_reg, unsigned ack_reg)
{
        struct irq_chip_generic *gc;

        gc = irq_get_domain_generic_chip(digicolor_irq_domain, irq_base);
        gc->reg_base = reg_base;
        gc->chip_types[0].regs.ack = ack_reg;
        gc->chip_types[0].regs.mask = en_reg;
        gc->chip_types[0].chip.irq_ack = irq_gc_ack_set_bit;
        gc->chip_types[0].chip.irq_mask = irq_gc_mask_clr_bit;
        gc->chip_types[0].chip.irq_unmask = irq_gc_mask_set_bit;
}

static int __init digicolor_of_init(struct device_node *node,
                                struct device_node *parent)
{
        void __iomem *reg_base;
        unsigned int clr = IRQ_NOREQUEST | IRQ_NOPROBE | IRQ_NOAUTOEN;
        struct regmap *ucregs;
        int ret;

        reg_base = of_iomap(node, 0);
        if (!reg_base) {
                pr_err("%pOF: unable to map IC registers\n", node);
                return -ENXIO;
        }

        /* disable all interrupts */
        writel(0, reg_base + IC_INT0ENABLE_LO);
        writel(0, reg_base + IC_INT0ENABLE_XLO);

        ucregs = syscon_regmap_lookup_by_phandle(node, "syscon");
        if (IS_ERR(ucregs)) {
                pr_err("%pOF: unable to map UC registers\n", node);
                return PTR_ERR(ucregs);
        }
        /* channel 1, regular IRQs */
        regmap_write(ucregs, UC_IRQ_CONTROL, 1);

        digicolor_irq_domain =
                irq_domain_create_linear(of_fwnode_handle(node), 64, &irq_generic_chip_ops, NULL);
        if (!digicolor_irq_domain) {
                pr_err("%pOF: unable to create IRQ domain\n", node);
                return -ENOMEM;
        }

        ret = irq_alloc_domain_generic_chips(digicolor_irq_domain, 32, 1,
                                             "digicolor_irq", handle_level_irq,
                                             clr, 0, 0);
        if (ret) {
                pr_err("%pOF: unable to allocate IRQ gc\n", node);
                return ret;
        }

        digicolor_set_gc(reg_base, 0, IC_INT0ENABLE_LO, IC_FLAG_CLEAR_LO);
        digicolor_set_gc(reg_base, 32, IC_INT0ENABLE_XLO, IC_FLAG_CLEAR_XLO);

        set_handle_irq(digicolor_handle_irq);

        return 0;
}
IRQCHIP_DECLARE(conexant_digicolor_ic, "cnxt,cx92755-ic", digicolor_of_init);