[PATCH] sparc64 pt_regs fixes

[deliverable/linux.git] / arch / sparc64 / kernel / irq.c

/* $Id: irq.c,v 1.114 2002/01/11 08:45:38 davem Exp $
 * irq.c: UltraSparc IRQ handling/init/registry.
 *
 * Copyright (C) 1997  David S. Miller  (davem@caip.rutgers.edu)
 * Copyright (C) 1998  Eddie C. Dost    (ecd@skynet.be)
 * Copyright (C) 1998  Jakub Jelinek    (jj@ultra.linux.cz)
 */

#include <linux/module.h>
#include <linux/sched.h>
#include <linux/ptrace.h>
#include <linux/errno.h>
#include <linux/kernel_stat.h>
#include <linux/signal.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/slab.h>
#include <linux/random.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/bootmem.h>
#include <linux/irq.h>

#include <asm/ptrace.h>
#include <asm/processor.h>
#include <asm/atomic.h>
#include <asm/system.h>
#include <asm/irq.h>
#include <asm/io.h>
#include <asm/sbus.h>
#include <asm/iommu.h>
#include <asm/upa.h>
#include <asm/oplib.h>
#include <asm/prom.h>
#include <asm/timer.h>
#include <asm/smp.h>
#include <asm/starfire.h>
#include <asm/uaccess.h>
#include <asm/cache.h>
#include <asm/cpudata.h>
#include <asm/auxio.h>
#include <asm/head.h>

/* UPA nodes send interrupt packet to UltraSparc with first data reg
 * value low 5 (7 on Starfire) bits holding the IRQ identifier being
 * delivered.  We must translate this into a non-vector IRQ so we can
 * set the softint on this cpu.
 *
 * To make processing these packets efficient and race free we use
 * an array of irq buckets below.  The interrupt vector handler in
 * entry.S feeds incoming packets into per-cpu pil-indexed lists.
 * The IVEC handler does not need to act atomically, the PIL dispatch
 * code uses CAS to get an atomic snapshot of the list and clear it
 * at the same time.
 *
 * If you make changes to ino_bucket, please update hand coded assembler
 * of the vectored interrupt trap handler(s) in entry.S and sun4v_ivec.S
 */
struct ino_bucket {
        /* Next handler in per-CPU IRQ worklist.  We know that
         * bucket pointers have the high 32-bits clear, so to
         * save space we only store the bits we need.
         */
/*0x00*/unsigned int irq_chain;

        /* Virtual interrupt number assigned to this INO.  */
/*0x04*/unsigned int virt_irq;
};

#define NUM_IVECS       (IMAP_INR + 1)
struct ino_bucket ivector_table[NUM_IVECS] __attribute__ ((aligned (SMP_CACHE_BYTES)));

#define __irq_ino(irq) \
        (((struct ino_bucket *)(unsigned long)(irq)) - &ivector_table[0])
#define __bucket(irq) ((struct ino_bucket *)(unsigned long)(irq))
#define __irq(bucket) ((unsigned int)(unsigned long)(bucket))

/* This has to be in the main kernel image, it cannot be
 * turned into per-cpu data.  The reason is that the main
 * kernel image is locked into the TLB and this structure
 * is accessed from the vectored interrupt trap handler.  If
 * access to this structure takes a TLB miss it could cause
 * the 5-level sparc v9 trap stack to overflow.
 */
#define irq_work(__cpu) &(trap_block[(__cpu)].irq_worklist)

static unsigned int virt_to_real_irq_table[NR_IRQS];
static unsigned char virt_irq_cur = 1;

static unsigned char virt_irq_alloc(unsigned int real_irq)
{
        unsigned char ent;

        BUILD_BUG_ON(NR_IRQS >= 256);

        ent = virt_irq_cur;
        if (ent >= NR_IRQS) {
                printk(KERN_ERR "IRQ: Out of virtual IRQs.\n");
                return 0;
        }

        virt_irq_cur = ent + 1;
        virt_to_real_irq_table[ent] = real_irq;

        return ent;
}

#if 0 /* Currently unused. */
static unsigned char real_to_virt_irq(unsigned int real_irq)
{
        struct ino_bucket *bucket = __bucket(real_irq);

        return bucket->virt_irq;
}
#endif

static unsigned int virt_to_real_irq(unsigned char virt_irq)
{
        return virt_to_real_irq_table[virt_irq];
}

/*
 * /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%d       ",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, " %9s", irq_desc[i].chip->typename);
                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);
        }
        return 0;
}

extern unsigned long real_hard_smp_processor_id(void);

static unsigned int sun4u_compute_tid(unsigned long imap, unsigned long cpuid)
{
        unsigned int tid;

        if (this_is_starfire) {
                tid = starfire_translate(imap, cpuid);
                tid <<= IMAP_TID_SHIFT;
                tid &= IMAP_TID_UPA;
        } else {
                if (tlb_type == cheetah || tlb_type == cheetah_plus) {
                        unsigned long ver;

                        __asm__ ("rdpr %%ver, %0" : "=r" (ver));
                        if ((ver >> 32UL) == __JALAPENO_ID ||
                            (ver >> 32UL) == __SERRANO_ID) {
                                tid = cpuid << IMAP_TID_SHIFT;
                                tid &= IMAP_TID_JBUS;
                        } else {
                                unsigned int a = cpuid & 0x1f;
                                unsigned int n = (cpuid >> 5) & 0x1f;

                                tid = ((a << IMAP_AID_SHIFT) |
                                       (n << IMAP_NID_SHIFT));
                                tid &= (IMAP_AID_SAFARI |
                                        IMAP_NID_SAFARI);;
                        }
                } else {
                        tid = cpuid << IMAP_TID_SHIFT;
                        tid &= IMAP_TID_UPA;
                }
        }

        return tid;
}

struct irq_handler_data {
        unsigned long   iclr;
        unsigned long   imap;

        void            (*pre_handler)(unsigned int, void *, void *);
        void            *pre_handler_arg1;
        void            *pre_handler_arg2;
};

static inline struct ino_bucket *virt_irq_to_bucket(unsigned int virt_irq)
{
        unsigned int real_irq = virt_to_real_irq(virt_irq);
        struct ino_bucket *bucket = NULL;

        if (likely(real_irq))
                bucket = __bucket(real_irq);

        return bucket;
}

#ifdef CONFIG_SMP
static int irq_choose_cpu(unsigned int virt_irq)
{
        cpumask_t mask = irq_desc[virt_irq].affinity;
        int cpuid;

        if (cpus_equal(mask, CPU_MASK_ALL)) {
                static int irq_rover;
                static DEFINE_SPINLOCK(irq_rover_lock);
                unsigned long flags;

                /* Round-robin distribution... */
        do_round_robin:
                spin_lock_irqsave(&irq_rover_lock, flags);

                while (!cpu_online(irq_rover)) {
                        if (++irq_rover >= NR_CPUS)
                                irq_rover = 0;
                }
                cpuid = irq_rover;
                do {
                        if (++irq_rover >= NR_CPUS)
                                irq_rover = 0;
                } while (!cpu_online(irq_rover));

                spin_unlock_irqrestore(&irq_rover_lock, flags);
        } else {
                cpumask_t tmp;

                cpus_and(tmp, cpu_online_map, mask);

                if (cpus_empty(tmp))
                        goto do_round_robin;

                cpuid = first_cpu(tmp);
        }

        return cpuid;
}
#else
static int irq_choose_cpu(unsigned int virt_irq)
{
        return real_hard_smp_processor_id();
}
#endif

static void sun4u_irq_enable(unsigned int virt_irq)
{
        irq_desc_t *desc = irq_desc + virt_irq;
        struct irq_handler_data *data = desc->handler_data;

        if (likely(data)) {
                unsigned long cpuid, imap;
                unsigned int tid;

                cpuid = irq_choose_cpu(virt_irq);
                imap = data->imap;

                tid = sun4u_compute_tid(imap, cpuid);

                upa_writel(tid | IMAP_VALID, imap);
        }
}

static void sun4u_irq_disable(unsigned int virt_irq)
{
        irq_desc_t *desc = irq_desc + virt_irq;
        struct irq_handler_data *data = desc->handler_data;

        if (likely(data)) {
                unsigned long imap = data->imap;
                u32 tmp = upa_readl(imap);

                tmp &= ~IMAP_VALID;
                upa_writel(tmp, imap);
        }
}

static void sun4u_irq_end(unsigned int virt_irq)
{
        irq_desc_t *desc = irq_desc + virt_irq;
        struct irq_handler_data *data = desc->handler_data;

        if (likely(data))
                upa_writel(ICLR_IDLE, data->iclr);
}

static void sun4v_irq_enable(unsigned int virt_irq)
{
        struct ino_bucket *bucket = virt_irq_to_bucket(virt_irq);
        unsigned int ino = bucket - &ivector_table[0];

        if (likely(bucket)) {
                unsigned long cpuid;
                int err;

                cpuid = irq_choose_cpu(virt_irq);

                err = sun4v_intr_settarget(ino, cpuid);
                if (err != HV_EOK)
                        printk("sun4v_intr_settarget(%x,%lu): err(%d)\n",
                               ino, cpuid, err);
                err = sun4v_intr_setenabled(ino, HV_INTR_ENABLED);
                if (err != HV_EOK)
                        printk("sun4v_intr_setenabled(%x): err(%d)\n",
                               ino, err);
        }
}

static void sun4v_irq_disable(unsigned int virt_irq)
{
        struct ino_bucket *bucket = virt_irq_to_bucket(virt_irq);
        unsigned int ino = bucket - &ivector_table[0];

        if (likely(bucket)) {
                int err;

                err = sun4v_intr_setenabled(ino, HV_INTR_DISABLED);
                if (err != HV_EOK)
                        printk("sun4v_intr_setenabled(%x): "
                               "err(%d)\n", ino, err);
        }
}

static void sun4v_irq_end(unsigned int virt_irq)
{
        struct ino_bucket *bucket = virt_irq_to_bucket(virt_irq);
        unsigned int ino = bucket - &ivector_table[0];

        if (likely(bucket)) {
                int err;

                err = sun4v_intr_setstate(ino, HV_INTR_STATE_IDLE);
                if (err != HV_EOK)
                        printk("sun4v_intr_setstate(%x): "
                               "err(%d)\n", ino, err);
        }
}

static void run_pre_handler(unsigned int virt_irq)
{
        struct ino_bucket *bucket = virt_irq_to_bucket(virt_irq);
        irq_desc_t *desc = irq_desc + virt_irq;
        struct irq_handler_data *data = desc->handler_data;

        if (likely(data->pre_handler)) {
                data->pre_handler(__irq_ino(__irq(bucket)),
                                  data->pre_handler_arg1,
                                  data->pre_handler_arg2);
        }
}

static struct hw_interrupt_type sun4u_irq = {
        .typename       = "sun4u",
        .enable         = sun4u_irq_enable,
        .disable        = sun4u_irq_disable,
        .end            = sun4u_irq_end,
};

static struct hw_interrupt_type sun4u_irq_ack = {
        .typename       = "sun4u+ack",
        .enable         = sun4u_irq_enable,
        .disable        = sun4u_irq_disable,
        .ack            = run_pre_handler,
        .end            = sun4u_irq_end,
};

static struct hw_interrupt_type sun4v_irq = {
        .typename       = "sun4v",
        .enable         = sun4v_irq_enable,
        .disable        = sun4v_irq_disable,
        .end            = sun4v_irq_end,
};

static struct hw_interrupt_type sun4v_irq_ack = {
        .typename       = "sun4v+ack",
        .enable         = sun4v_irq_enable,
        .disable        = sun4v_irq_disable,
        .ack            = run_pre_handler,
        .end            = sun4v_irq_end,
};

void irq_install_pre_handler(int virt_irq,
                             void (*func)(unsigned int, void *, void *),
                             void *arg1, void *arg2)
{
        irq_desc_t *desc = irq_desc + virt_irq;
        struct irq_handler_data *data = desc->handler_data;

        data->pre_handler = func;
        data->pre_handler_arg1 = arg1;
        data->pre_handler_arg2 = arg2;

        if (desc->chip == &sun4u_irq_ack ||
            desc->chip == &sun4v_irq_ack)
                return;

        desc->chip = (desc->chip == &sun4u_irq ?
                      &sun4u_irq_ack : &sun4v_irq_ack);
}

unsigned int build_irq(int inofixup, unsigned long iclr, unsigned long imap)
{
        struct ino_bucket *bucket;
        struct irq_handler_data *data;
        irq_desc_t *desc;
        int ino;

        BUG_ON(tlb_type == hypervisor);

        ino = (upa_readl(imap) & (IMAP_IGN | IMAP_INO)) + inofixup;
        bucket = &ivector_table[ino];
        if (!bucket->virt_irq) {
                bucket->virt_irq = virt_irq_alloc(__irq(bucket));
                irq_desc[bucket->virt_irq].chip = &sun4u_irq;
        }

        desc = irq_desc + bucket->virt_irq;
        if (unlikely(desc->handler_data))
                goto out;

        data = kzalloc(sizeof(struct irq_handler_data), GFP_ATOMIC);
        if (unlikely(!data)) {
                prom_printf("IRQ: kzalloc(irq_handler_data) failed.\n");
                prom_halt();
        }
        desc->handler_data = data;

        data->imap  = imap;
        data->iclr  = iclr;

out:
        return bucket->virt_irq;
}

unsigned int sun4v_build_irq(u32 devhandle, unsigned int devino)
{
        struct ino_bucket *bucket;
        struct irq_handler_data *data;
        unsigned long sysino;
        irq_desc_t *desc;

        BUG_ON(tlb_type != hypervisor);

        sysino = sun4v_devino_to_sysino(devhandle, devino);
        bucket = &ivector_table[sysino];
        if (!bucket->virt_irq) {
                bucket->virt_irq = virt_irq_alloc(__irq(bucket));
                irq_desc[bucket->virt_irq].chip = &sun4v_irq;
        }

        desc = irq_desc + bucket->virt_irq;
        if (unlikely(desc->handler_data))
                goto out;

        data = kzalloc(sizeof(struct irq_handler_data), GFP_ATOMIC);
        if (unlikely(!data)) {
                prom_printf("IRQ: kzalloc(irq_handler_data) failed.\n");
                prom_halt();
        }
        desc->handler_data = data;

        /* Catch accidental accesses to these things.  IMAP/ICLR handling
         * is done by hypervisor calls on sun4v platforms, not by direct
         * register accesses.
         */
        data->imap = ~0UL;
        data->iclr = ~0UL;

out:
        return bucket->virt_irq;
}

void hw_resend_irq(struct hw_interrupt_type *handler, unsigned int virt_irq)
{
        struct ino_bucket *bucket = virt_irq_to_bucket(virt_irq);
        unsigned long pstate;
        unsigned int *ent;

        __asm__ __volatile__("rdpr %%pstate, %0" : "=r" (pstate));
        __asm__ __volatile__("wrpr %0, %1, %%pstate"
                             : : "r" (pstate), "i" (PSTATE_IE));
        ent = irq_work(smp_processor_id());
        bucket->irq_chain = *ent;
        *ent = __irq(bucket);
        set_softint(1 << PIL_DEVICE_IRQ);
        __asm__ __volatile__("wrpr %0, 0x0, %%pstate" : : "r" (pstate));
}

void ack_bad_irq(unsigned int virt_irq)
{
        struct ino_bucket *bucket = virt_irq_to_bucket(virt_irq);
        unsigned int ino = 0xdeadbeef;

        if (bucket)
                ino = bucket - &ivector_table[0];

        printk(KERN_CRIT "Unexpected IRQ from ino[%x] virt_irq[%u]\n",
               ino, virt_irq);
}

#ifndef CONFIG_SMP
extern irqreturn_t timer_interrupt(int, void *, struct pt_regs *);

void timer_irq(int irq, struct pt_regs *regs)
{
        unsigned long clr_mask = 1 << irq;
        unsigned long tick_mask = tick_ops->softint_mask;

        if (get_softint() & tick_mask) {
                irq = 0;
                clr_mask = tick_mask;
        }
        clear_softint(clr_mask);

        irq_enter();

        kstat_this_cpu.irqs[0]++;
        timer_interrupt(irq, NULL, regs);

        irq_exit();
}
#endif

void handler_irq(int irq, struct pt_regs *regs)
{
        struct ino_bucket *bucket;
        struct pt_regs *old_regs;

        clear_softint(1 << irq);

        old_regs = set_irq_regs(regs);
        irq_enter();

        /* Sliiiick... */
        bucket = __bucket(xchg32(irq_work(smp_processor_id()), 0));
        while (bucket) {
                struct ino_bucket *next = __bucket(bucket->irq_chain);

                bucket->irq_chain = 0;
                __do_IRQ(bucket->virt_irq);

                bucket = next;
        }

        irq_exit();
        set_irq_regs(old_regs);
}

struct sun5_timer {
        u64     count0;
        u64     limit0;
        u64     count1;
        u64     limit1;
};

static struct sun5_timer *prom_timers;
static u64 prom_limit0, prom_limit1;

static void map_prom_timers(void)
{
        struct device_node *dp;
        unsigned int *addr;

        /* PROM timer node hangs out in the top level of device siblings... */
        dp = of_find_node_by_path("/");
        dp = dp->child;
        while (dp) {
                if (!strcmp(dp->name, "counter-timer"))
                        break;
                dp = dp->sibling;
        }

        /* Assume if node is not present, PROM uses different tick mechanism
         * which we should not care about.
         */
        if (!dp) {
                prom_timers = (struct sun5_timer *) 0;
                return;
        }

        /* If PROM is really using this, it must be mapped by him. */
        addr = of_get_property(dp, "address", NULL);
        if (!addr) {
                prom_printf("PROM does not have timer mapped, trying to continue.\n");
                prom_timers = (struct sun5_timer *) 0;
                return;
        }
        prom_timers = (struct sun5_timer *) ((unsigned long)addr[0]);
}

static void kill_prom_timer(void)
{
        if (!prom_timers)
                return;

        /* Save them away for later. */
        prom_limit0 = prom_timers->limit0;
        prom_limit1 = prom_timers->limit1;

        /* Just as in sun4c/sun4m PROM uses timer which ticks at IRQ 14.
         * We turn both off here just to be paranoid.
         */
        prom_timers->limit0 = 0;
        prom_timers->limit1 = 0;

        /* Wheee, eat the interrupt packet too... */
        __asm__ __volatile__(
"       mov     0x40, %%g2\n"
"       ldxa    [%%g0] %0, %%g1\n"
"       ldxa    [%%g2] %1, %%g1\n"
"       stxa    %%g0, [%%g0] %0\n"
"       membar  #Sync\n"
        : /* no outputs */
        : "i" (ASI_INTR_RECEIVE), "i" (ASI_INTR_R)
        : "g1", "g2");
}

void init_irqwork_curcpu(void)
{
        int cpu = hard_smp_processor_id();

        trap_block[cpu].irq_worklist = 0;
}

static void __cpuinit register_one_mondo(unsigned long paddr, unsigned long type)
{
        unsigned long num_entries = 128;
        unsigned long status;

        status = sun4v_cpu_qconf(type, paddr, num_entries);
        if (status != HV_EOK) {
                prom_printf("SUN4V: sun4v_cpu_qconf(%lu:%lx:%lu) failed, "
                            "err %lu\n", type, paddr, num_entries, status);
                prom_halt();
        }
}

static void __cpuinit sun4v_register_mondo_queues(int this_cpu)
{
        struct trap_per_cpu *tb = &trap_block[this_cpu];

        register_one_mondo(tb->cpu_mondo_pa, HV_CPU_QUEUE_CPU_MONDO);
        register_one_mondo(tb->dev_mondo_pa, HV_CPU_QUEUE_DEVICE_MONDO);
        register_one_mondo(tb->resum_mondo_pa, HV_CPU_QUEUE_RES_ERROR);
        register_one_mondo(tb->nonresum_mondo_pa, HV_CPU_QUEUE_NONRES_ERROR);
}

static void __cpuinit alloc_one_mondo(unsigned long *pa_ptr, int use_bootmem)
{
        void *page;

        if (use_bootmem)
                page = alloc_bootmem_low_pages(PAGE_SIZE);
        else
                page = (void *) get_zeroed_page(GFP_ATOMIC);

        if (!page) {
                prom_printf("SUN4V: Error, cannot allocate mondo queue.\n");
                prom_halt();
        }

        *pa_ptr = __pa(page);
}

static void __cpuinit alloc_one_kbuf(unsigned long *pa_ptr, int use_bootmem)
{
        void *page;

        if (use_bootmem)
                page = alloc_bootmem_low_pages(PAGE_SIZE);
        else
                page = (void *) get_zeroed_page(GFP_ATOMIC);

        if (!page) {
                prom_printf("SUN4V: Error, cannot allocate kbuf page.\n");
                prom_halt();
        }

        *pa_ptr = __pa(page);
}

static void __cpuinit init_cpu_send_mondo_info(struct trap_per_cpu *tb, int use_bootmem)
{
#ifdef CONFIG_SMP
        void *page;

        BUILD_BUG_ON((NR_CPUS * sizeof(u16)) > (PAGE_SIZE - 64));

        if (use_bootmem)
                page = alloc_bootmem_low_pages(PAGE_SIZE);
        else
                page = (void *) get_zeroed_page(GFP_ATOMIC);

        if (!page) {
                prom_printf("SUN4V: Error, cannot allocate cpu mondo page.\n");
                prom_halt();
        }

        tb->cpu_mondo_block_pa = __pa(page);
        tb->cpu_list_pa = __pa(page + 64);
#endif
}

/* Allocate and register the mondo and error queues for this cpu.  */
void __cpuinit sun4v_init_mondo_queues(int use_bootmem, int cpu, int alloc, int load)
{
        struct trap_per_cpu *tb = &trap_block[cpu];

        if (alloc) {
                alloc_one_mondo(&tb->cpu_mondo_pa, use_bootmem);
                alloc_one_mondo(&tb->dev_mondo_pa, use_bootmem);
                alloc_one_mondo(&tb->resum_mondo_pa, use_bootmem);
                alloc_one_kbuf(&tb->resum_kernel_buf_pa, use_bootmem);
                alloc_one_mondo(&tb->nonresum_mondo_pa, use_bootmem);
                alloc_one_kbuf(&tb->nonresum_kernel_buf_pa, use_bootmem);

                init_cpu_send_mondo_info(tb, use_bootmem);
        }

        if (load) {
                if (cpu != hard_smp_processor_id()) {
                        prom_printf("SUN4V: init mondo on cpu %d not %d\n",
                                    cpu, hard_smp_processor_id());
                        prom_halt();
                }
                sun4v_register_mondo_queues(cpu);
        }
}

static struct irqaction timer_irq_action = {
        .name = "timer",
};

/* Only invoked on boot processor. */
void __init init_IRQ(void)
{
        map_prom_timers();
        kill_prom_timer();
        memset(&ivector_table[0], 0, sizeof(ivector_table));

        if (tlb_type == hypervisor)
                sun4v_init_mondo_queues(1, hard_smp_processor_id(), 1, 1);

        /* We need to clear any IRQ's pending in the soft interrupt
         * registers, a spurious one could be left around from the
         * PROM timer which we just disabled.
         */
        clear_softint(get_softint());

        /* Now that ivector table is initialized, it is safe
         * to receive IRQ vector traps.  We will normally take
         * one or two right now, in case some device PROM used
         * to boot us wants to speak to us.  We just ignore them.
         */
        __asm__ __volatile__("rdpr      %%pstate, %%g1\n\t"
                             "or        %%g1, %0, %%g1\n\t"
                             "wrpr      %%g1, 0x0, %%pstate"
                             : /* No outputs */
                             : "i" (PSTATE_IE)
                             : "g1");

        irq_desc[0].action = &timer_irq_action;
}