irq.c

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/*  $Id: irq.c,v 1.109 2000/08/31 10:00:39 anton Exp $
 *  arch/sparc/kernel/irq.c:  Interrupt request handling routines. On the
 *                            Sparc the IRQ's are basically 'cast in stone'
 *                            and you are supposed to probe the prom's device
 *                            node trees to find out who's got which IRQ.
 *
 *  Copyright (C) 1995 David S. Miller ([e-mail])
 *  Copyright (C) 1995 Miguel de Icaza ([e-mail])
 *  Copyright (C) 1995 Pete A. Zaitcev ([e-mail])
 *  Copyright (C) 1996 Dave Redman ([e-mail])
 *  Copyright (C) 1998-2000 Anton Blanchard ([e-mail])
 */

#include <linux/config.h>
#include <linux/ptrace.h>
#include <linux/errno.h>
#include <linux/linkage.h>
#include <linux/kernel_stat.h>
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/interrupt.h>
#include <linux/malloc.h>
#include <linux/random.h>
#include <linux/init.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>
#include <linux/delay.h>
#include <linux/threads.h>
#include <linux/spinlock.h>

#include <asm/ptrace.h>
#include <asm/processor.h>
#include <asm/system.h>
#include <asm/psr.h>
#include <asm/smp.h>
#include <asm/vaddrs.h>
#include <asm/timer.h>
#include <asm/openprom.h>
#include <asm/oplib.h>
#include <asm/traps.h>
#include <asm/irq.h>
#include <asm/io.h>
#include <asm/pgalloc.h>
#include <asm/pgtable.h>
#include <asm/hardirq.h>
#include <asm/softirq.h>
#include <asm/pcic.h>

/*
 * Dave Redman ([e-mail])
 *
 * IRQ numbers.. These are no longer restricted to 15..
 *
 * this is done to enable SBUS cards and onboard IO to be masked
 * correctly. using the interrupt level isn't good enough.
 *
 * For example:
 *   A device interrupting at sbus level6 and the Floppy both come in
 *   at IRQ11, but enabling and disabling them requires writing to
 *   different bits in the SLAVIO/SEC.
 *
 * As a result of these changes sun4m machines could now support
 * directed CPU interrupts using the existing enable/disable irq code
 * with tweaks.
 *
 */

static void irq_panic(void)
{
    extern char *cputypval;
    prom_printf("machine: %s doesn't have irq handlers defined!\n",cputypval);
    prom_halt();
}

void (*init_timers)(void (*)(int, void *,struct pt_regs *)) =
    (void (*)(void (*)(int, void *,struct pt_regs *))) irq_panic;

/*
 * Dave Redman ([e-mail])
 *
 * There used to be extern calls and hard coded values here.. very sucky!
 * instead, because some of the devices attach very early, I do something
 * equally sucky but at least we'll never try to free statically allocated
 * space or call kmalloc before kmalloc_init :(.
 * 
 * In fact it's the timer10 that attaches first.. then timer14
 * then kmalloc_init is called.. then the tty interrupts attach.
 * hmmm....
 *
 */
#define MAX_STATIC_ALLOC	4
struct irqaction static_irqaction[MAX_STATIC_ALLOC];
int static_irq_count = 0;

struct irqaction *irq_action[NR_IRQS+1] = {
	  NULL, NULL, NULL, NULL, NULL, NULL , NULL, NULL,
	  NULL, NULL, NULL, NULL, NULL, NULL , NULL, NULL
};

int get_irq_list(char *buf)
{
	int i, len = 0;
	struct irqaction * action;
#ifdef CONFIG_SMP
	int j;
#endif

	if (sparc_cpu_model == sun4d) {
		extern int sun4d_get_irq_list(char *);
		
		return sun4d_get_irq_list(buf);
	}
	for (i = 0 ; i < (NR_IRQS+1) ; i++) {
	        action = *(i + irq_action);
		if (!action) 
		        continue;
		len += sprintf(buf+len, "%3d: ", i);
#ifndef CONFIG_SMP
		len += sprintf(buf+len, "%10u ", kstat_irqs(i));
#else
		for (j = 0; j < smp_num_cpus; j++)
			len += sprintf(buf+len, "%10u ",
				kstat.irqs[cpu_logical_map(j)][i]);
#endif
		len += sprintf(buf+len, " %c %s",
			(action->flags & SA_INTERRUPT) ? '+' : ' ',
			action->name);
		for (action=action->next; action; action = action->next) {
			len += sprintf(buf+len, ",%s %s",
				(action->flags & SA_INTERRUPT) ? " +" : "",
				action->name);
		}
		len += sprintf(buf+len, "\n");
	}
	return len;
}

void free_irq(unsigned int irq, void *dev_id)
{
	struct irqaction * action;
	struct irqaction * tmp = NULL;
        unsigned long flags;
	unsigned int cpu_irq;
	
	if (sparc_cpu_model == sun4d) {
		extern void sun4d_free_irq(unsigned int, void *);
		
		return sun4d_free_irq(irq, dev_id);
	}
	cpu_irq = irq & NR_IRQS;
	action = *(cpu_irq + irq_action);
        if (cpu_irq > 14) {  /* 14 irq levels on the sparc */
                printk("Trying to free bogus IRQ %d\n", irq);
                return;
        }
	if (!action->handler) {
		printk("Trying to free free IRQ%d\n",irq);
		return;
	}
	if (dev_id) {
		for (; action; action = action->next) {
			if (action->dev_id == dev_id)
				break;
			tmp = action;
		}
		if (!action) {
			printk("Trying to free free shared IRQ%d\n",irq);
			return;
		}
	} else if (action->flags & SA_SHIRQ) {
		printk("Trying to free shared IRQ%d with NULL device ID\n", irq);
		return;
	}
	if (action->flags & SA_STATIC_ALLOC)
	{
	    /* This interrupt is marked as specially allocated
	     * so it is a bad idea to free it.
	     */
	    printk("Attempt to free statically allocated IRQ%d (%s)\n",
		   irq, action->name);
	    return;
	}
	
        save_and_cli(flags);
	if (action && tmp)
		tmp->next = action->next;
	else
		*(cpu_irq + irq_action) = action->next;

	kfree(action);

	if (!(*(cpu_irq + irq_action)))
		disable_irq(irq);

        restore_flags(flags);
}

#ifdef CONFIG_SMP

/* Who has the global irq brlock */
unsigned char global_irq_holder = NO_PROC_ID;

void smp_show_backtrace_all_cpus(void);
void show_backtrace(void);

#define VERBOSE_DEBUG_IRQLOCK
#define MAXCOUNT 100000000

static void show(char * str)
{
	int cpu = smp_processor_id();
	int i;

	printk("\n%s, CPU %d:\n", str, cpu);
	printk("irq:  %d [ ", irqs_running());
	for (i = 0; i < smp_num_cpus; i++)
		printk("%u ", __brlock_array[i][BR_GLOBALIRQ_LOCK]);
	printk("]\nbh:   %d [ ",
	       (spin_is_locked(&global_bh_lock) ? 1 : 0));
	for (i = 0; i < smp_num_cpus; i++)
		printk("%u ", local_bh_count(i));
	printk("]\n");

#ifdef VERBOSE_DEBUG_IRQLOCK
	smp_show_backtrace_all_cpus();
#else
	show_backtrace();
#endif
}


/*
 * We have to allow irqs to arrive between __sti and __cli
 */
#define SYNC_OTHER_CORES(x) barrier()

/*
 * This is called when we want to synchronize with
 * interrupts. We may for example tell a device to
 * stop sending interrupts: but to make sure there
 * are no interrupts that are executing on another
 * CPU we need to call this function.
 */
void synchronize_irq(void)
{
	if (irqs_running()) {
		cli();
		sti();
	}
}

static inline void get_irqlock(int cpu)
{
	int count;

	if ((unsigned char)cpu == global_irq_holder)
		return;

	count = MAXCOUNT;
again:
	br_write_lock(BR_GLOBALIRQ_LOCK);
	for (;;) {
		spinlock_t *lock;

		if (!irqs_running() &&
		    (local_bh_count(smp_processor_id()) || !spin_is_locked(&global_bh_lock)))
			break;

		br_write_unlock(BR_GLOBALIRQ_LOCK);
		lock = &__br_write_locks[BR_GLOBALIRQ_LOCK].lock;
		while (irqs_running() ||
		       spin_is_locked(lock) ||
		       (!local_bh_count(smp_processor_id()) && spin_is_locked(&global_bh_lock))) {
			if (!--count) {
				show("get_irqlock");
				count = (~0 >> 1);
			}
			__sti();
			SYNC_OTHER_CORES(cpu);
			__cli();
		}
		goto again;
	}

	global_irq_holder = cpu;
}

/*
 * A global "cli()" while in an interrupt context
 * turns into just a local cli(). Interrupts
 * should use spinlocks for the (very unlikely)
 * case that they ever want to protect against
 * each other.
 *
 * If we already have local interrupts disabled,
 * this will not turn a local disable into a
 * global one (problems with spinlocks: this makes
 * save_flags+cli+sti usable inside a spinlock).
 */
void __global_cli(void)
{
	unsigned long flags;

	__save_flags(flags);

	if ((flags & PSR_PIL) != PSR_PIL) {
		int cpu = smp_processor_id();
		__cli();
		if (!local_irq_count(cpu))
			get_irqlock(cpu);
	}
}

void __global_sti(void)
{
	int cpu = smp_processor_id();

	if (!local_irq_count(cpu))
		release_irqlock(cpu);
	__sti();
}

/*
 * SMP flags value to restore to:
 * 0 - global cli
 * 1 - global sti
 * 2 - local cli
 * 3 - local sti
 */
unsigned long __global_save_flags(void)
{
	unsigned long flags, retval;
	unsigned long local_enabled = 0;