/*
 *      linux/arch/i386/kernel/irq.c
 *
 *      Copyright (C) 1992, 1998 Linus Torvalds, Ingo Molnar
 *
 * This file contains the lowest level x86-specific interrupt
 * entry, irq-stacks and irq statistics code. All the remaining
 * irq logic is done by the generic kernel/irq/ code and
 * by the x86-specific irq controller code. (e.g. i8259.c and
 * io_apic.c.)
 */

#include <linux/module.h>
#include <linux/seq_file.h>
#include <linux/interrupt.h>
#include <linux/kernel_stat.h>
#include <linux/notifier.h>
#include <linux/cpu.h>
#include <linux/delay.h>

#include <asm/apic.h>
#include <asm/uaccess.h>

DEFINE_PER_CPU(irq_cpustat_t, irq_stat) ____cacheline_internodealigned_in_smp;
EXPORT_PER_CPU_SYMBOL(irq_stat);

DEFINE_PER_CPU(struct pt_regs *, irq_regs);
EXPORT_PER_CPU_SYMBOL(irq_regs);

/*
 * 'what should we do if we get a hw irq event on an illegal vector'.
 * each architecture has to answer this themselves.
 */
void ack_bad_irq(unsigned int irq)
{
        printk(KERN_ERR "unexpected IRQ trap at vector %02x\n", irq);

#ifdef CONFIG_X86_LOCAL_APIC
        /*
         * Currently unexpected vectors happen only on SMP and APIC.
         * We _must_ ack these because every local APIC has only N
         * irq slots per priority level, and a 'hanging, unacked' IRQ
         * holds up an irq slot - in excessive cases (when multiple
         * unexpected vectors occur) that might lock up the APIC
         * completely.
         * But only ack when the APIC is enabled -AK
         */
        if (cpu_has_apic)
                ack_APIC_irq();
#endif
}

#ifdef CONFIG_4KSTACKS
/*
 * per-CPU IRQ handling contexts (thread information and stack)
 */
union irq_ctx {
        struct thread_info      tinfo;
        u32                     stack[THREAD_SIZE/sizeof(u32)];
};

static union irq_ctx *hardirq_ctx[NR_CPUS] __read_mostly;
static union irq_ctx *softirq_ctx[NR_CPUS] __read_mostly;
#endif

/*
 * do_IRQ handles all normal device IRQ's (the special
 * SMP cross-CPU interrupts have their own specific
 * handlers).
 */
fastcall unsigned int do_IRQ(struct pt_regs *regs)
{       
        struct pt_regs *old_regs;
        /* high bit used in ret_from_ code */
        int irq = ~regs->orig_eax;
        struct irq_desc *desc = irq_desc + irq;
#ifdef CONFIG_4KSTACKS
        union irq_ctx *curctx, *irqctx;
        u32 *isp;
#endif

        if (unlikely((unsigned)irq >= NR_IRQS)) {
                printk(KERN_EMERG "%s: cannot handle IRQ %d\n",
                                        __FUNCTION__, irq);
                BUG();
        }

        old_regs = set_irq_regs(regs);
        irq_enter();
#ifdef CONFIG_DEBUG_STACKOVERFLOW
        /* Debugging check for stack overflow: is there less than 1KB free? */
        {
                long esp;

                __asm__ __volatile__("andl %%esp,%0" :
                                        "=r" (esp) : "0" (THREAD_SIZE - 1));
                if (unlikely(esp < (sizeof(struct thread_info) + STACK_WARN))) {
                        printk("do_IRQ: stack overflow: %ld\n",
                                esp - sizeof(struct thread_info));
                        dump_stack();
                }
        }
#endif

#ifdef CONFIG_4KSTACKS

        curctx = (union irq_ctx *) current_thread_info();
        irqctx = hardirq_ctx[smp_processor_id()];

        /*
         * this is where we switch to the IRQ stack. However, if we are
         * already using the IRQ stack (because we interrupted a hardirq
         * handler) we can't do that and just have to keep using the
         * current stack (which is the irq stack already after all)
         */
        if (curctx != irqctx) {
                int arg1, arg2, ebx;

                /* build the stack frame on the IRQ stack */
                isp = (u32*) ((char*)irqctx + sizeof(*irqctx));
                irqctx->tinfo.task = curctx->tinfo.task;
                irqctx->tinfo.previous_esp = current_stack_pointer;

                /*
                 * Copy the softirq bits in preempt_count so that the
                 * softirq checks work in the hardirq context.
                 */
                irqctx->tinfo.preempt_count =
                        (irqctx->tinfo.preempt_count & ~SOFTIRQ_MASK) |
                        (curctx->tinfo.preempt_count & SOFTIRQ_MASK);

                asm volatile(
                        "       xchgl  %%ebx,%%esp      \n"
                        "       call   *%%edi           \n"
                        "       movl   %%ebx,%%esp      \n"
                        : "=a" (arg1), "=d" (arg2), "=b" (ebx)
                        :  "0" (irq),   "1" (desc),  "2" (isp),
                           "D" (desc->handle_irq)
                        : "memory", "cc"
                );
        } else
#endif
                desc->handle_irq(irq, desc);

        irq_exit();
        set_irq_regs(old_regs);
        return 1;
}

#ifdef CONFIG_4KSTACKS

/*
 * These should really be __section__(".bss.page_aligned") as well, but
 * gcc's 3.0 and earlier don't handle that correctly.
 */
static char softirq_stack[NR_CPUS * THREAD_SIZE]
                __attribute__((__aligned__(THREAD_SIZE)));

static char hardirq_stack[NR_CPUS * THREAD_SIZE]
                __attribute__((__aligned__(THREAD_SIZE)));

/*
 * allocate per-cpu stacks for hardirq and for softirq processing
 */
void irq_ctx_init(int cpu)
{
        union irq_ctx *irqctx;

        if (hardirq_ctx[cpu])
                return;

        irqctx = (union irq_ctx*) &hardirq_stack[cpu*THREAD_SIZE];
        irqctx->tinfo.task              = NULL;
        irqctx->tinfo.exec_domain       = NULL;
        irqctx->tinfo.cpu               = cpu;
        irqctx->tinfo.preempt_count     = HARDIRQ_OFFSET;
        irqctx->tinfo.addr_limit        = MAKE_MM_SEG(0);

        hardirq_ctx[cpu] = irqctx;

        irqctx = (union irq_ctx*) &softirq_stack[cpu*THREAD_SIZE];
        irqctx->tinfo.task              = NULL;
        irqctx->tinfo.exec_domain       = NULL;
        irqctx->tinfo.cpu               = cpu;
        irqctx->tinfo.preempt_count     = 0;
        irqctx->tinfo.addr_limit        = MAKE_MM_SEG(0);

        softirq_ctx[cpu] = irqctx;

        printk("CPU %u irqstacks, hard=%p soft=%p\n",
                cpu,hardirq_ctx[cpu],softirq_ctx[cpu]);
}

void irq_ctx_exit(int cpu)
{
        hardirq_ctx[cpu] = NULL;
}

extern asmlinkage void __do_softirq(void);

asmlinkage void do_softirq(void)
{
        unsigned long flags;
        struct thread_info *curctx;
        union irq_ctx *irqctx;
        u32 *isp;

        if (in_interrupt())
                return;

        local_irq_save(flags);

        if (local_softirq_pending()) {
                curctx = current_thread_info();
                irqctx = softirq_ctx[smp_processor_id()];
                irqctx->tinfo.task = curctx->task;
                irqctx->tinfo.previous_esp = current_stack_pointer;

                /* build the stack frame on the softirq stack */
                isp = (u32*) ((char*)irqctx + sizeof(*irqctx));

                asm volatile(
                        "       xchgl   %%ebx,%%esp     \n"
                        "       call    __do_softirq    \n"
                        "       movl    %%ebx,%%esp     \n"
                        : "=b"(isp)
                        : "0"(isp)
                        : "memory", "cc", "edx", "ecx", "eax"
                );
                /*
                 * Shouldnt happen, we returned above if in_interrupt():
                 */
                WARN_ON_ONCE(softirq_count());
        }

        local_irq_restore(flags);
}

EXPORT_SYMBOL(do_softirq);
#endif

/*
 * Interrupt statistics:
 */

atomic_t irq_err_count;

/*
 * /proc/interrupts printing:
 */

int show_interrupts(struct seq_file *p, void *v)
{
        int i = *(loff_t *) v, j;
        struct irqaction * action;
        unsigned long flags;

        if (i == 0) {
                seq_printf(p, "           ");
                for_each_online_cpu(j)
                        seq_printf(p, "CPU%-8d",j);
                seq_putc(p, '\n');
        }

        if (i < NR_IRQS) {
                spin_lock_irqsave(&irq_desc[i].lock, flags);
                action = irq_desc[i].action;
                if (!action)
                        goto skip;
                seq_printf(p, "%3d: ",i);
#ifndef CONFIG_SMP
                seq_printf(p, "%10u ", kstat_irqs(i));
#else
                for_each_online_cpu(j)
                        seq_printf(p, "%10u ", kstat_cpu(j).irqs[i]);
#endif
                seq_printf(p, " %8s", irq_desc[i].chip->name);
                seq_printf(p, "-%-8s", irq_desc[i].name);
                seq_printf(p, "  %s", action->name);

                for (action=action->next; action; action = action->next)
                        seq_printf(p, ", %s", action->name);

                seq_putc(p, '\n');
skip:
                spin_unlock_irqrestore(&irq_desc[i].lock, flags);
        } else if (i == NR_IRQS) {
                seq_printf(p, "NMI: ");
                for_each_online_cpu(j)
                        seq_printf(p, "%10u ", nmi_count(j));
                seq_putc(p, '\n');
#ifdef CONFIG_X86_LOCAL_APIC
                seq_printf(p, "LOC: ");
                for_each_online_cpu(j)
                        seq_printf(p, "%10u ",
                                per_cpu(irq_stat,j).apic_timer_irqs);
                seq_putc(p, '\n');
#endif
                seq_printf(p, "ERR: %10u\n", atomic_read(&irq_err_count));
#if defined(CONFIG_X86_IO_APIC)
                seq_printf(p, "MIS: %10u\n", atomic_read(&irq_mis_count));
#endif
        }
        return 0;
}

#ifdef CONFIG_HOTPLUG_CPU
#include <mach_apic.h>

void fixup_irqs(cpumask_t map)
{
        unsigned int irq;
        static int warned;

        for (irq = 0; irq < NR_IRQS; irq++) {
                cpumask_t mask;
                if (irq == 2)
                        continue;

                cpus_and(mask, irq_desc[irq].affinity, map);
                if (any_online_cpu(mask) == NR_CPUS) {
                        printk("Breaking affinity for irq %i\n", irq);
                        mask = map;
                }
                if (irq_desc[irq].chip->set_affinity)
                        irq_desc[irq].chip->set_affinity(irq, mask);
                else if (irq_desc[irq].action && !(warned++))
                        printk("Cannot set affinity for irq %i\n", irq);
        }

#if 0
        barrier();
        /* Ingo Molnar says: "after the IO-APIC masks have been redirected
           [note the nop - the interrupt-enable boundary on x86 is two
           instructions from sti] - to flush out pending hardirqs and
           IPIs. After this point nothing is supposed to reach this CPU." */
        __asm__ __volatile__("sti; nop; cli");
        barrier();
#else
        /* That doesn't seem sufficient.  Give it 1ms. */
        local_irq_enable();
        mdelay(1);
        local_irq_disable();
#endif
}
#endif