/*
 * linux/arch/ia64/kernel/irq.c
 *
 * Copyright (C) 1998-2001 Hewlett-Packard Co
 *      Stephane Eranian <eranian@hpl.hp.com>
 *      David Mosberger-Tang <davidm@hpl.hp.com>
 *
 *  6/10/99: Updated to bring in sync with x86 version to facilitate
 *           support for SMP and different interrupt controllers.
 *
 * 09/15/00 Goutham Rao <goutham.rao@intel.com> Implemented pci_irq_to_vector
 *                      PCI to vector allocation routine.
 * 04/14/2004 Ashok Raj <ashok.raj@intel.com>
 *                                              Added CPU Hotplug handling for IPF.
 */

#include <linux/module.h>

#include <linux/jiffies.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/ioport.h>
#include <linux/kernel_stat.h>
#include <linux/slab.h>
#include <linux/ptrace.h>
#include <linux/random.h>       /* for rand_initialize_irq() */
#include <linux/signal.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>
#include <linux/threads.h>
#include <linux/bitops.h>

#include <asm/delay.h>
#include <asm/intrinsics.h>
#include <asm/io.h>
#include <asm/hw_irq.h>
#include <asm/machvec.h>
#include <asm/pgtable.h>
#include <asm/system.h>

#ifdef CONFIG_PERFMON
# include <asm/perfmon.h>
#endif

#define IRQ_DEBUG       0

/* These can be overridden in platform_irq_init */
int ia64_first_device_vector = IA64_DEF_FIRST_DEVICE_VECTOR;
int ia64_last_device_vector = IA64_DEF_LAST_DEVICE_VECTOR;

/* default base addr of IPI table */
void __iomem *ipi_base_addr = ((void __iomem *)
                               (__IA64_UNCACHED_OFFSET | IA64_IPI_DEFAULT_BASE_ADDR));

/*
 * Legacy IRQ to IA-64 vector translation table.
 */
__u8 isa_irq_to_vector_map[16] = {
        /* 8259 IRQ translation, first 16 entries */
        0x2f, 0x20, 0x2e, 0x2d, 0x2c, 0x2b, 0x2a, 0x29,
        0x28, 0x27, 0x26, 0x25, 0x24, 0x23, 0x22, 0x21
};
EXPORT_SYMBOL(isa_irq_to_vector_map);

static unsigned long ia64_vector_mask[BITS_TO_LONGS(IA64_MAX_DEVICE_VECTORS)];

int
assign_irq_vector (int irq)
{
        int pos, vector;
 again:
        pos = find_first_zero_bit(ia64_vector_mask, IA64_NUM_DEVICE_VECTORS);
        vector = IA64_FIRST_DEVICE_VECTOR + pos;
        if (vector > IA64_LAST_DEVICE_VECTOR)
                return -ENOSPC;
        if (test_and_set_bit(pos, ia64_vector_mask))
                goto again;
        return vector;
}

void
free_irq_vector (int vector)
{
        int pos;

        if (vector < IA64_FIRST_DEVICE_VECTOR || vector > IA64_LAST_DEVICE_VECTOR)
                return;

        pos = vector - IA64_FIRST_DEVICE_VECTOR;
        if (!test_and_clear_bit(pos, ia64_vector_mask))
                printk(KERN_WARNING "%s: double free!\n", __FUNCTION__);
}

int
reserve_irq_vector (int vector)
{
        int pos;

        if (vector < IA64_FIRST_DEVICE_VECTOR ||
            vector > IA64_LAST_DEVICE_VECTOR)
                return -EINVAL;

        pos = vector - IA64_FIRST_DEVICE_VECTOR;
        return test_and_set_bit(pos, ia64_vector_mask);
}

#ifdef CONFIG_SMP
#       define IS_RESCHEDULE(vec)       (vec == IA64_IPI_RESCHEDULE)
#else
#       define IS_RESCHEDULE(vec)       (0)
#endif
/*
 * That's where the IVT branches when we get an external
 * interrupt. This branches to the correct hardware IRQ handler via
 * function ptr.
 */
void
ia64_handle_irq (ia64_vector vector, struct pt_regs *regs)
{
        unsigned long saved_tpr;

#if IRQ_DEBUG
        {
                unsigned long bsp, sp;

                /*
                 * Note: if the interrupt happened while executing in
                 * the context switch routine (ia64_switch_to), we may
                 * get a spurious stack overflow here.  This is
                 * because the register and the memory stack are not
                 * switched atomically.
                 */
                bsp = ia64_getreg(_IA64_REG_AR_BSP);
                sp = ia64_getreg(_IA64_REG_SP);

                if ((sp - bsp) < 1024) {
                        static unsigned char count;
                        static long last_time;

                        if (jiffies - last_time > 5*HZ)
                                count = 0;
                        if (++count < 5) {
                                last_time = jiffies;
                                printk("ia64_handle_irq: DANGER: less than "
                                       "1KB of free stack space!!\n"
                                       "(bsp=0x%lx, sp=%lx)\n", bsp, sp);
                        }
                }
        }
#endif /* IRQ_DEBUG */

        /*
         * Always set TPR to limit maximum interrupt nesting depth to
         * 16 (without this, it would be ~240, which could easily lead
         * to kernel stack overflows).
         */
        irq_enter();
        saved_tpr = ia64_getreg(_IA64_REG_CR_TPR);
        ia64_srlz_d();
        while (vector != IA64_SPURIOUS_INT_VECTOR) {
                if (!IS_RESCHEDULE(vector)) {
                        ia64_setreg(_IA64_REG_CR_TPR, vector);
                        ia64_srlz_d();

                        __do_IRQ(local_vector_to_irq(vector), regs);

                        /*
                         * Disable interrupts and send EOI:
                         */
                        local_irq_disable();
                        ia64_setreg(_IA64_REG_CR_TPR, saved_tpr);
                }
                ia64_eoi();
                vector = ia64_get_ivr();
        }
        /*
         * This must be done *after* the ia64_eoi().  For example, the keyboard softirq
         * handler needs to be able to wait for further keyboard interrupts, which can't
         * come through until ia64_eoi() has been done.
         */
        irq_exit();
}

#ifdef CONFIG_HOTPLUG_CPU
/*
 * This function emulates a interrupt processing when a cpu is about to be
 * brought down.
 */
void ia64_process_pending_intr(void)
{
        ia64_vector vector;
        unsigned long saved_tpr;
        extern unsigned int vectors_in_migration[NR_IRQS];

        vector = ia64_get_ivr();

         irq_enter();
         saved_tpr = ia64_getreg(_IA64_REG_CR_TPR);
         ia64_srlz_d();

         /*
          * Perform normal interrupt style processing
          */
        while (vector != IA64_SPURIOUS_INT_VECTOR) {
                if (!IS_RESCHEDULE(vector)) {
                        ia64_setreg(_IA64_REG_CR_TPR, vector);
                        ia64_srlz_d();

                        /*
                         * Now try calling normal ia64_handle_irq as it would have got called
                         * from a real intr handler. Try passing null for pt_regs, hopefully
                         * it will work. I hope it works!.
                         * Probably could shared code.
                         */
                        vectors_in_migration[local_vector_to_irq(vector)]=0;
                        __do_IRQ(local_vector_to_irq(vector), NULL);

                        /*
                         * Disable interrupts and send EOI
                         */
                        local_irq_disable();
                        ia64_setreg(_IA64_REG_CR_TPR, saved_tpr);
                }
                ia64_eoi();
                vector = ia64_get_ivr();
        }
        irq_exit();
}
#endif


#ifdef CONFIG_SMP
extern irqreturn_t handle_IPI (int irq, void *dev_id, struct pt_regs *regs);

static struct irqaction ipi_irqaction = {
        .handler =      handle_IPI,
        .flags =        IRQF_DISABLED,
        .name =         "IPI"
};
#endif

void
register_percpu_irq (ia64_vector vec, struct irqaction *action)
{
        irq_desc_t *desc;
        unsigned int irq;

        for (irq = 0; irq < NR_IRQS; ++irq)
                if (irq_to_vector(irq) == vec) {
                        desc = irq_desc + irq;
                        desc->status |= IRQ_PER_CPU;
                        desc->chip = &irq_type_ia64_lsapic;
                        if (action)
                                setup_irq(irq, action);
                }
}

void __init
init_IRQ (void)
{
        register_percpu_irq(IA64_SPURIOUS_INT_VECTOR, NULL);
#ifdef CONFIG_SMP
        register_percpu_irq(IA64_IPI_VECTOR, &ipi_irqaction);
#endif
#ifdef CONFIG_PERFMON
        pfm_init_percpu();
#endif
        platform_irq_init();
}

void
ia64_send_ipi (int cpu, int vector, int delivery_mode, int redirect)
{
        void __iomem *ipi_addr;
        unsigned long ipi_data;
        unsigned long phys_cpu_id;

#ifdef CONFIG_SMP
        phys_cpu_id = cpu_physical_id(cpu);
#else
        phys_cpu_id = (ia64_getreg(_IA64_REG_CR_LID) >> 16) & 0xffff;
#endif

        /*
         * cpu number is in 8bit ID and 8bit EID
         */

        ipi_data = (delivery_mode << 8) | (vector & 0xff);
        ipi_addr = ipi_base_addr + ((phys_cpu_id << 4) | ((redirect & 1) << 3));

        writeq(ipi_data, ipi_addr);
}