/*
 * linux/arch/arm/mach-omap2/irq.c
 *
 * Interrupt handler for OMAP2 boards.
 *
 * Copyright (C) 2005 Nokia Corporation
 * Author: Paul Mundt <paul.mundt@nokia.com>
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License. See the file "COPYING" in the main directory of this archive
 * for more details.
 */
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/io.h>

#include <asm/exception.h>
#include <linux/irqchip.h>
#include <linux/irqdomain.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>

#include <linux/irqchip/irq-omap-intc.h>

/* selected INTC register offsets */

#define INTC_REVISION           0x0000
#define INTC_SYSCONFIG          0x0010
#define INTC_SYSSTATUS          0x0014
#define INTC_SIR                0x0040
#define INTC_CONTROL            0x0048
#define INTC_PROTECTION         0x004C
#define INTC_IDLE               0x0050
#define INTC_THRESHOLD          0x0068
#define INTC_MIR0               0x0084
#define INTC_MIR_CLEAR0         0x0088
#define INTC_MIR_SET0           0x008c
#define INTC_PENDING_IRQ0       0x0098
#define INTC_PENDING_IRQ1       0x00b8
#define INTC_PENDING_IRQ2       0x00d8
#define INTC_PENDING_IRQ3       0x00f8
#define INTC_ILR0               0x0100

#define ACTIVEIRQ_MASK          0x7f    /* omap2/3 active interrupt bits */
#define SPURIOUSIRQ_MASK        (0x1ffffff << 7)
#define INTCPS_NR_ILR_REGS      128
#define INTCPS_NR_MIR_REGS      4

#define INTC_IDLE_FUNCIDLE      (1 << 0)
#define INTC_IDLE_TURBO         (1 << 1)

#define INTC_PROTECTION_ENABLE  (1 << 0)

struct omap_intc_regs {
        u32 sysconfig;
        u32 protection;
        u32 idle;
        u32 threshold;
        u32 ilr[INTCPS_NR_ILR_REGS];
        u32 mir[INTCPS_NR_MIR_REGS];
};
static struct omap_intc_regs intc_context;

static struct irq_domain *domain;
static void __iomem *omap_irq_base;
static int omap_nr_pending;
static int omap_nr_irqs;

static void intc_writel(u32 reg, u32 val)
{
        writel_relaxed(val, omap_irq_base + reg);
}

static u32 intc_readl(u32 reg)
{
        return readl_relaxed(omap_irq_base + reg);
}

void omap_intc_save_context(void)
{
        int i;

        intc_context.sysconfig =
                intc_readl(INTC_SYSCONFIG);
        intc_context.protection =
                intc_readl(INTC_PROTECTION);
        intc_context.idle =
                intc_readl(INTC_IDLE);
        intc_context.threshold =
                intc_readl(INTC_THRESHOLD);

        for (i = 0; i < omap_nr_irqs; i++)
                intc_context.ilr[i] =
                        intc_readl((INTC_ILR0 + 0x4 * i));
        for (i = 0; i < INTCPS_NR_MIR_REGS; i++)
                intc_context.mir[i] =
                        intc_readl(INTC_MIR0 + (0x20 * i));
}

void omap_intc_restore_context(void)
{
        int i;

        intc_writel(INTC_SYSCONFIG, intc_context.sysconfig);
        intc_writel(INTC_PROTECTION, intc_context.protection);
        intc_writel(INTC_IDLE, intc_context.idle);
        intc_writel(INTC_THRESHOLD, intc_context.threshold);

        for (i = 0; i < omap_nr_irqs; i++)
                intc_writel(INTC_ILR0 + 0x4 * i,
                                intc_context.ilr[i]);

        for (i = 0; i < INTCPS_NR_MIR_REGS; i++)
                intc_writel(INTC_MIR0 + 0x20 * i,
                        intc_context.mir[i]);
        /* MIRs are saved and restore with other PRCM registers */
}

void omap3_intc_prepare_idle(void)
{
        /*
         * Disable autoidle as it can stall interrupt controller,
         * cf. errata ID i540 for 3430 (all revisions up to 3.1.x)
         */
        intc_writel(INTC_SYSCONFIG, 0);
        intc_writel(INTC_IDLE, INTC_IDLE_TURBO);
}

void omap3_intc_resume_idle(void)
{
        /* Re-enable autoidle */
        intc_writel(INTC_SYSCONFIG, 1);
        intc_writel(INTC_IDLE, 0);
}

/* XXX: FIQ and additional INTC support (only MPU at the moment) */
static void omap_ack_irq(struct irq_data *d)
{
        intc_writel(INTC_CONTROL, 0x1);
}

static void omap_mask_ack_irq(struct irq_data *d)
{
        irq_gc_mask_disable_reg(d);
        omap_ack_irq(d);
}

static void __init omap_irq_soft_reset(void)
{
        unsigned long tmp;

        tmp = intc_readl(INTC_REVISION) & 0xff;

        pr_info("IRQ: Found an INTC at 0x%p (revision %ld.%ld) with %d interrupts\n",
                omap_irq_base, tmp >> 4, tmp & 0xf, omap_nr_irqs);

        tmp = intc_readl(INTC_SYSCONFIG);
        tmp |= 1 << 1;  /* soft reset */
        intc_writel(INTC_SYSCONFIG, tmp);

        while (!(intc_readl(INTC_SYSSTATUS) & 0x1))
                /* Wait for reset to complete */;

        /* Enable autoidle */
        intc_writel(INTC_SYSCONFIG, 1 << 0);
}

int omap_irq_pending(void)
{
        int i;

        for (i = 0; i < omap_nr_pending; i++)
                if (intc_readl(INTC_PENDING_IRQ0 + (0x20 * i)))
                        return 1;
        return 0;
}

void omap3_intc_suspend(void)
{
        /* A pending interrupt would prevent OMAP from entering suspend */
        omap_ack_irq(NULL);
}

static int __init omap_alloc_gc_of(struct irq_domain *d, void __iomem *base)
{
        int ret;
        int i;

        ret = irq_alloc_domain_generic_chips(d, 32, 1, "INTC",
                        handle_level_irq, IRQ_NOREQUEST | IRQ_NOPROBE,
                        IRQ_LEVEL, 0);
        if (ret) {
                pr_warn("Failed to allocate irq chips\n");
                return ret;
        }

        for (i = 0; i < omap_nr_pending; i++) {
                struct irq_chip_generic *gc;
                struct irq_chip_type *ct;

                gc = irq_get_domain_generic_chip(d, 32 * i);
                gc->reg_base = base;
                ct = gc->chip_types;

                ct->type = IRQ_TYPE_LEVEL_MASK;

                ct->chip.irq_ack = omap_mask_ack_irq;
                ct->chip.irq_mask = irq_gc_mask_disable_reg;
                ct->chip.irq_unmask = irq_gc_unmask_enable_reg;

                ct->chip.flags |= IRQCHIP_SKIP_SET_WAKE;

                ct->regs.enable = INTC_MIR_CLEAR0 + 32 * i;
                ct->regs.disable = INTC_MIR_SET0 + 32 * i;
        }

        return 0;
}

static void __init omap_alloc_gc_legacy(void __iomem *base,
                unsigned int irq_start, unsigned int num)
{
        struct irq_chip_generic *gc;
        struct irq_chip_type *ct;

        gc = irq_alloc_generic_chip("INTC", 1, irq_start, base,
                        handle_level_irq);
        ct = gc->chip_types;
        ct->chip.irq_ack = omap_mask_ack_irq;
        ct->chip.irq_mask = irq_gc_mask_disable_reg;
        ct->chip.irq_unmask = irq_gc_unmask_enable_reg;
        ct->chip.flags |= IRQCHIP_SKIP_SET_WAKE;

        ct->regs.enable = INTC_MIR_CLEAR0;
        ct->regs.disable = INTC_MIR_SET0;
        irq_setup_generic_chip(gc, IRQ_MSK(num), IRQ_GC_INIT_MASK_CACHE,
                        IRQ_NOREQUEST | IRQ_NOPROBE, 0);
}

static int __init omap_init_irq_of(struct device_node *node)
{
        int ret;

        omap_irq_base = of_iomap(node, 0);
        if (WARN_ON(!omap_irq_base))
                return -ENOMEM;

        domain = irq_domain_add_linear(node, omap_nr_irqs,
                        &irq_generic_chip_ops, NULL);

        omap_irq_soft_reset();

        ret = omap_alloc_gc_of(domain, omap_irq_base);
        if (ret < 0)
                irq_domain_remove(domain);

        return ret;
}

static int __init omap_init_irq_legacy(u32 base, struct device_node *node)
{
        int j, irq_base;

        omap_irq_base = ioremap(base, SZ_4K);
        if (WARN_ON(!omap_irq_base))
                return -ENOMEM;

        irq_base = irq_alloc_descs(-1, 0, omap_nr_irqs, 0);
        if (irq_base < 0) {
                pr_warn("Couldn't allocate IRQ numbers\n");
                irq_base = 0;
        }

        domain = irq_domain_add_legacy(node, omap_nr_irqs, irq_base, 0,
                        &irq_domain_simple_ops, NULL);

        omap_irq_soft_reset();

        for (j = 0; j < omap_nr_irqs; j += 32)
                omap_alloc_gc_legacy(omap_irq_base + j, j + irq_base, 32);

        return 0;
}

static void __init omap_irq_enable_protection(void)
{
        u32 reg;

        reg = intc_readl(INTC_PROTECTION);
        reg |= INTC_PROTECTION_ENABLE;
        intc_writel(INTC_PROTECTION, reg);
}

static int __init omap_init_irq(u32 base, struct device_node *node)
{
        int ret;

        /*
         * FIXME legacy OMAP DMA driver sitting under arch/arm/plat-omap/dma.c
         * depends is still not ready for linear IRQ domains; because of that
         * we need to temporarily "blacklist" OMAP2 and OMAP3 devices from using
         * linear IRQ Domain until that driver is finally fixed.
         */
        if (of_device_is_compatible(node, "ti,omap2-intc") ||
                        of_device_is_compatible(node, "ti,omap3-intc")) {
                struct resource res;

                if (of_address_to_resource(node, 0, &res))
                        return -ENOMEM;

                base = res.start;
                ret = omap_init_irq_legacy(base, node);
        } else if (node) {
                ret = omap_init_irq_of(node);
        } else {
                ret = omap_init_irq_legacy(base, NULL);
        }

        if (ret == 0)
                omap_irq_enable_protection();

        return ret;
}

static asmlinkage void __exception_irq_entry
omap_intc_handle_irq(struct pt_regs *regs)
{
        extern unsigned long irq_err_count;
        u32 irqnr;

        irqnr = intc_readl(INTC_SIR);

        /*
         * A spurious IRQ can result if interrupt that triggered the
         * sorting is no longer active during the sorting (10 INTC
         * functional clock cycles after interrupt assertion). Or a
         * change in interrupt mask affected the result during sorting
         * time. There is no special handling required except ignoring
         * the SIR register value just read and retrying.
         * See section 6.2.5 of AM335x TRM Literature Number: SPRUH73K
         *
         * Many a times, a spurious interrupt situation has been fixed
         * by adding a flush for the posted write acking the IRQ in
         * the device driver. Typically, this is going be the device
         * driver whose interrupt was handled just before the spurious
         * IRQ occurred. Pay attention to those device drivers if you
         * run into hitting the spurious IRQ condition below.
         */
        if (unlikely((irqnr & SPURIOUSIRQ_MASK) == SPURIOUSIRQ_MASK)) {
                pr_err_once("%s: spurious irq!\n", __func__);
                irq_err_count++;
                omap_ack_irq(NULL);
                return;
        }

        irqnr &= ACTIVEIRQ_MASK;
        handle_domain_irq(domain, irqnr, regs);
}

static int __init intc_of_init(struct device_node *node,
                             struct device_node *parent)
{
        int ret;

        omap_nr_pending = 3;
        omap_nr_irqs = 96;

        if (WARN_ON(!node))
                return -ENODEV;

        if (of_device_is_compatible(node, "ti,dm814-intc") ||
            of_device_is_compatible(node, "ti,dm816-intc") ||
            of_device_is_compatible(node, "ti,am33xx-intc")) {
                omap_nr_irqs = 128;
                omap_nr_pending = 4;
        }

        ret = omap_init_irq(-1, of_node_get(node));
        if (ret < 0)
                return ret;

        set_handle_irq(omap_intc_handle_irq);

        return 0;
}

IRQCHIP_DECLARE(omap2_intc, "ti,omap2-intc", intc_of_init);
IRQCHIP_DECLARE(omap3_intc, "ti,omap3-intc", intc_of_init);
IRQCHIP_DECLARE(dm814x_intc, "ti,dm814-intc", intc_of_init);
IRQCHIP_DECLARE(dm816x_intc, "ti,dm816-intc", intc_of_init);
IRQCHIP_DECLARE(am33xx_intc, "ti,am33xx-intc", intc_of_init);