/*
 * Copyright (C) 2006, 2008 Atmel Corporation
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/clk.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/platform_device.h>
#include <linux/sysdev.h>

#include <asm/io.h>

#include "intc.h"

struct intc {
        void __iomem            *regs;
        struct irq_chip         chip;
        struct sys_device       sysdev;
#ifdef CONFIG_PM
        unsigned long           suspend_ipr;
        unsigned long           saved_ipr[64];
#endif
};

extern struct platform_device at32_intc0_device;

/*
 * TODO: We may be able to implement mask/unmask by setting IxM flags
 * in the status register.
 */
static void intc_mask_irq(unsigned int irq)
{

}

static void intc_unmask_irq(unsigned int irq)
{

}

static struct intc intc0 = {
        .chip = {
                .name           = "intc",
                .mask           = intc_mask_irq,
                .unmask         = intc_unmask_irq,
        },
};

/*
 * All interrupts go via intc at some point.
 */
asmlinkage void do_IRQ(int level, struct pt_regs *regs)
{
        struct irq_desc *desc;
        struct pt_regs *old_regs;
        unsigned int irq;
        unsigned long status_reg;

        local_irq_disable();

        old_regs = set_irq_regs(regs);

        irq_enter();

        irq = intc_readl(&intc0, INTCAUSE0 - 4 * level);
        desc = irq_desc + irq;
        desc->handle_irq(irq, desc);

        /*
         * Clear all interrupt level masks so that we may handle
         * interrupts during softirq processing.  If this is a nested
         * interrupt, interrupts must stay globally disabled until we
         * return.
         */
        status_reg = sysreg_read(SR);
        status_reg &= ~(SYSREG_BIT(I0M) | SYSREG_BIT(I1M)
                        | SYSREG_BIT(I2M) | SYSREG_BIT(I3M));
        sysreg_write(SR, status_reg);

        irq_exit();

        set_irq_regs(old_regs);
}

void __init init_IRQ(void)
{
        extern void _evba(void);
        extern void irq_level0(void);
        struct resource *regs;
        struct clk *pclk;
        unsigned int i;
        u32 offset, readback;

        regs = platform_get_resource(&at32_intc0_device, IORESOURCE_MEM, 0);
        if (!regs) {
                printk(KERN_EMERG "intc: no mmio resource defined\n");
                goto fail;
        }
        pclk = clk_get(&at32_intc0_device.dev, "pclk");
        if (IS_ERR(pclk)) {
                printk(KERN_EMERG "intc: no clock defined\n");
                goto fail;
        }

        clk_enable(pclk);

        intc0.regs = ioremap(regs->start, regs->end - regs->start + 1);
        if (!intc0.regs) {
                printk(KERN_EMERG "intc: failed to map registers (0x%08lx)\n",
                       (unsigned long)regs->start);
                goto fail;
        }

        /*
         * Initialize all interrupts to level 0 (lowest priority). The
         * priority level may be changed by calling
         * irq_set_priority().
         *
         */
        offset = (unsigned long)&irq_level0 - (unsigned long)&_evba;
        for (i = 0; i < NR_INTERNAL_IRQS; i++) {
                intc_writel(&intc0, INTPR0 + 4 * i, offset);
                readback = intc_readl(&intc0, INTPR0 + 4 * i);
                if (readback == offset)
                        set_irq_chip_and_handler(i, &intc0.chip,
                                                 handle_simple_irq);
        }

        /* Unmask all interrupt levels */
        sysreg_write(SR, (sysreg_read(SR)
                          & ~(SR_I3M | SR_I2M | SR_I1M | SR_I0M)));

        return;

fail:
        panic("Interrupt controller initialization failed!\n");
}

#ifdef CONFIG_PM
void intc_set_suspend_handler(unsigned long offset)
{
        intc0.suspend_ipr = offset;
}

static int intc_suspend(struct sys_device *sdev, pm_message_t state)
{
        struct intc *intc = container_of(sdev, struct intc, sysdev);
        int i;

        if (unlikely(!irqs_disabled())) {
                pr_err("intc_suspend: called with interrupts enabled\n");
                return -EINVAL;
        }

        if (unlikely(!intc->suspend_ipr)) {
                pr_err("intc_suspend: suspend_ipr not initialized\n");
                return -EINVAL;
        }

        for (i = 0; i < 64; i++) {
                intc->saved_ipr[i] = intc_readl(intc, INTPR0 + 4 * i);
                intc_writel(intc, INTPR0 + 4 * i, intc->suspend_ipr);
        }

        return 0;
}

static int intc_resume(struct sys_device *sdev)
{
        struct intc *intc = container_of(sdev, struct intc, sysdev);
        int i;

        WARN_ON(!irqs_disabled());

        for (i = 0; i < 64; i++)
                intc_writel(intc, INTPR0 + 4 * i, intc->saved_ipr[i]);

        return 0;
}
#else
#define intc_suspend    NULL
#define intc_resume     NULL
#endif

static struct sysdev_class intc_class = {
        .name           = "intc",
        .suspend        = intc_suspend,
        .resume         = intc_resume,
};

static int __init intc_init_sysdev(void)
{
        int ret;

        ret = sysdev_class_register(&intc_class);
        if (ret)
                return ret;

        intc0.sysdev.id = 0;
        intc0.sysdev.cls = &intc_class;
        ret = sysdev_register(&intc0.sysdev);

        return ret;
}
device_initcall(intc_init_sysdev);

unsigned long intc_get_pending(unsigned int group)
{
        return intc_readl(&intc0, INTREQ0 + 4 * group);
}
EXPORT_SYMBOL_GPL(intc_get_pending);