irq.c

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/*
 * linux/arch/sh/kernel/irq.c
 *
 *  Copyright (C) 1992, 1998 Linus Torvalds, Ingo Molnar
 *
 *
 * SuperH version:  Copyright (C) 1999  Niibe Yutaka
 */
#include <linux/irq.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/kernel_stat.h>
#include <linux/seq_file.h>
#include <linux/ftrace.h>
#include <linux/delay.h>
#include <linux/ratelimit.h>
#include <asm/processor.h>
#include <asm/machvec.h>
#include <asm/uaccess.h>
#include <asm/thread_info.h>
#include <cpu/mmu_context.h>

atomic_t irq_err_count;

/*
 * 'what should we do if we get a hw irq event on an illegal vector'.
 * each architecture has to answer this themselves, it doesn't deserve
 * a generic callback i think.
 */
void ack_bad_irq(unsigned int irq)
{
    atomic_inc(&irq_err_count);
    printk("unexpected IRQ trap at vector %02x\n", irq);
}

#if defined(CONFIG_PROC_FS)
/*
 * /proc/interrupts printing for arch specific interrupts
 */
int arch_show_interrupts(struct seq_file *p, int prec)
{
    int j;

    seq_printf(p, "%*s: ", prec, "NMI");
    for_each_online_cpu(j)
        seq_printf(p, "%10u ", irq_stat[j].__nmi_count);
    seq_printf(p, "  Non-maskable interrupts\n");

    seq_printf(p, "%*s: %10u\n", prec, "ERR", atomic_read(&irq_err_count));

    return 0;
}
#endif

#ifdef CONFIG_IRQSTACKS
/*
 * 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;

static char softirq_stack[NR_CPUS * THREAD_SIZE] __page_aligned_bss;
static char hardirq_stack[NR_CPUS * THREAD_SIZE] __page_aligned_bss;

static inline void handle_one_irq(unsigned int irq)
{
    union irq_ctx *curctx, *irqctx;

    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) {
        u32 *isp;

        isp = (u32 *)((char *)irqctx + sizeof(*irqctx));
        irqctx->tinfo.task = curctx->tinfo.task;
        irqctx->tinfo.previous_sp = 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__ (
            "mov    %0, r4      \n"
            "mov    r15, r8     \n"
            "jsr    @%1     \n"
            /* swith to the irq stack */
            " mov   %2, r15     \n"
            /* restore the stack (ring zero) */
            "mov    r8, r15     \n"
            : /* no outputs */
            : "r" (irq), "r" (generic_handle_irq), "r" (isp)
            : "memory", "r0", "r1", "r2", "r3", "r4",
              "r5", "r6", "r7", "r8", "t", "pr"
        );
    } else
        generic_handle_irq(irq);
}

/*
 * 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;
}

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_sp = current_stack_pointer;

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

        __asm__ __volatile__ (
            "mov    r15, r9     \n"
            "jsr    @%0     \n"
            /* switch to the softirq stack */
            " mov   %1, r15     \n"
            /* restore the thread stack */
            "mov    r9, r15     \n"
            : /* no outputs */
            : "r" (__do_softirq), "r" (isp)
            : "memory", "r0", "r1", "r2", "r3", "r4",
              "r5", "r6", "r7", "r8", "r9", "r15", "t", "pr"
        );

        /*
         * Shouldn't happen, we returned above if in_interrupt():
         */
        WARN_ON_ONCE(softirq_count());
    }

    local_irq_restore(flags);
}
#else
static inline void handle_one_irq(unsigned int irq)
{
    generic_handle_irq(irq);
}
#endif

asmlinkage __irq_entry int do_IRQ(unsigned int irq, struct pt_regs *regs)
{
    struct pt_regs *old_regs = set_irq_regs(regs);

    irq_enter();

    irq = irq_demux(irq_lookup(irq));

    if (irq != NO_IRQ_IGNORE) {
        handle_one_irq(irq);
        irq_finish(irq);
    }

    irq_exit();

    set_irq_regs(old_regs);

    return IRQ_HANDLED;
}

void __init init_IRQ(void)
{
    plat_irq_setup();

    /* Perform the machine specific initialisation */
    if (sh_mv.mv_init_irq)
        sh_mv.mv_init_irq();

    intc_finalize();

    irq_ctx_init(smp_processor_id());
}

#ifdef CONFIG_HOTPLUG_CPU
static void route_irq(struct irq_data *data, unsigned int irq, unsigned int cpu)
{
    struct irq_desc *desc = irq_to_desc(irq);
    struct irq_chip *chip = irq_data_get_irq_chip(data);

    printk(KERN_INFO "IRQ%u: moving from cpu%u to cpu%u\n",
           irq, data->node, cpu);

    raw_spin_lock_irq(&desc->lock);
    chip->irq_set_affinity(data, cpumask_of(cpu), false);
    raw_spin_unlock_irq(&desc->lock);
}

/*
 * The CPU has been marked offline.  Migrate IRQs off this CPU.  If
 * the affinity settings do not allow other CPUs, force them onto any
 * available CPU.
 */
void migrate_irqs(void)
{
    unsigned int irq, cpu = smp_processor_id();

    for_each_active_irq(irq) {
        struct irq_data *data = irq_get_irq_data(irq);

        if (data->node == cpu) {
            unsigned int newcpu = cpumask_any_and(data->affinity,
                                  cpu_online_mask);
            if (newcpu >= nr_cpu_ids) {
                pr_info_ratelimited("IRQ%u no longer affine to CPU%u\n",
                            irq, cpu);

                cpumask_setall(data->affinity);
                newcpu = cpumask_any_and(data->affinity,
                             cpu_online_mask);
            }

            route_irq(data, irq, newcpu);
        }
    }
}
#endif