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/*
* linux/arch/arm/kernel/irq.c
*
* Copyright (C) 1992 Linus Torvalds
* Modifications for ARM processor Copyright (C) 1995-2000 Russell King.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This file contains the code used by various IRQ handling routines:
* asking for different IRQ's should be done through these routines
* instead of just grabbing them. Thus setups with different IRQ numbers
* shouldn't result in any weird surprises, and installing new handlers
* should be easier.
*
* IRQ's are in fact implemented a bit like signal handlers for the kernel.
* Naturally it's not a 1:1 relation, but there are similarities.
*/
#include <linux/config.h>
#include <linux/ptrace.h>
#include <linux/kernel_stat.h>
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/ioport.h>
#include <linux/interrupt.h>
#include <linux/slab.h>
#include <linux/random.h>
#include <linux/smp.h>
#include <linux/init.h>
#include <asm/irq.h>
#include <asm/system.h>
#include <asm/mach/irq.h>
#include <asm/arch/irq.h> /* pick up fixup_irq definition */
/*
* Maximum IRQ count. Currently, this is arbitary. However, it should
* not be set too low to prevent false triggering. Conversely, if it
* is set too high, then you could miss a stuck IRQ.
*
* Maybe we ought to set a timer and re-enable the IRQ at a later time?
*/
#define MAX_IRQ_CNT 100000
static volatile unsigned long irq_err_count;
static spinlock_t irq_controller_lock;
struct irqdesc irq_desc[NR_IRQS];
void (*init_arch_irq)(void) __initdata = NULL;
/*
* Dummy mask/unmask handler
*/
static void dummy_mask_unmask_irq(unsigned int irq)
{
}
/**
* disable_irq - disable an irq and wait for completion
* @irq: Interrupt to disable
*
* Disable the selected interrupt line.
*
* This function may be called - with care - from IRQ context.
*/
void disable_irq(unsigned int irq)
{
unsigned long flags;
spin_lock_irqsave(&irq_controller_lock, flags);
irq_desc[irq].enabled = 0;
irq_desc[irq].mask(irq);
spin_unlock_irqrestore(&irq_controller_lock, flags);
}
/**
* enable_irq - enable interrupt handling on an irq
* @irq: Interrupt to enable
*
* Re-enables the processing of interrupts on this IRQ line
*
* This function may be called from IRQ context.
*/
void enable_irq(unsigned int irq)
{
unsigned long flags;
spin_lock_irqsave(&irq_controller_lock, flags);
irq_desc[irq].probing = 0;
irq_desc[irq].triggered = 0;
irq_desc[irq].enabled = 1;
irq_desc[irq].unmask(irq);
spin_unlock_irqrestore(&irq_controller_lock, flags);
}
int get_irq_list(char *buf)
{
int i;
struct irqaction * action;
char *p = buf;
for (i = 0 ; i < NR_IRQS ; i++) {
action = irq_desc[i].action;
if (!action)
continue;
p += sprintf(p, "%3d: %10u ", i, kstat_irqs(i));
p += sprintf(p, " %s", action->name);
for (action = action->next; action; action = action->next) {
p += sprintf(p, ", %s", action->name);
}
*p++ = '\n';
}
#ifdef CONFIG_ARCH_ACORN
p += get_fiq_list(p);
#endif
p += sprintf(p, "Err: %10lu\n", irq_err_count);
return p - buf;
}
/*
* IRQ lock detection.
*
* Hopefully, this should get us out of a few locked situations.
* However, it may take a while for this to happen, since we need
* a large number if IRQs to appear in the same jiffie with the
* same instruction pointer (or within 2 instructions).
*/
static void check_irq_lock(struct irqdesc *desc, int irq, struct pt_regs *regs)
{
unsigned long instr_ptr = instruction_pointer(regs);
if (desc->lck_jif == jiffies &&
desc->lck_pc >= instr_ptr && desc->lck_pc < instr_ptr + 8) {
desc->lck_cnt += 1;
if (desc->lck_cnt > MAX_IRQ_CNT) {
printk(KERN_ERR "IRQ LOCK: IRQ%d is locking the system, disabled\n", irq);
disable_irq(irq);
}
} else {
desc->lck_cnt = 0;
desc->lck_pc = instruction_pointer(regs);
desc->lck_jif = jiffies;
}
}
/*
* do_IRQ handles all normal device IRQ's
*/
asmlinkage void do_IRQ(int irq, struct pt_regs * regs)
{
struct irqdesc * desc;
struct irqaction * action;
int cpu;
irq = fixup_irq(irq);
/*
* Some hardware gives randomly wrong interrupts. Rather
* than crashing, do something sensible.
*/
if (irq >= NR_IRQS)
goto bad_irq;
desc = irq_desc + irq;
spin_lock(&irq_controller_lock);
desc->mask_ack(irq);
spin_unlock(&irq_controller_lock);
cpu = smp_processor_id();
irq_enter(cpu, irq);
kstat.irqs[cpu][irq]++;
desc->triggered = 1;
/* Return with this interrupt masked if no action */
action = desc->action;
if (action) {
int status = 0;
if (desc->nomask) {
spin_lock(&irq_controller_lock);
desc->unmask(irq);
spin_unlock(&irq_controller_lock);
}
if (!(action->flags & SA_INTERRUPT))
__sti();
do {
status |= action->flags;
action->handler(irq, action->dev_id, regs);
action = action->next;
} while (action);
if (status & SA_SAMPLE_RANDOM)
add_interrupt_randomness(irq);
__cli();
if (!desc->nomask && desc->enabled) {
spin_lock(&irq_controller_lock);
desc->unmask(irq);
spin_unlock(&irq_controller_lock);
}
}
/*
* Debug measure - hopefully we can continue if an
* IRQ lockup problem occurs...
*/
check_irq_lock(desc, irq, regs);
irq_exit(cpu, irq);
if (softirq_pending(cpu))
do_softirq();
return;
bad_irq:
irq_err_count += 1;
printk(KERN_ERR "IRQ: spurious interrupt %d\n", irq);
return;
}
#ifdef CONFIG_ARCH_ACORN
void do_ecard_IRQ(int irq, struct pt_regs *regs)
{
struct irqdesc * desc;
struct irqaction * action;
int cpu;
desc = irq_desc + irq;
cpu = smp_processor_id();
kstat.irqs[cpu][irq]++;
desc->triggered = 1;
action = desc->action;
if (action) {
do {
action->handler(irq, action->dev_id, regs);
action = action->next;
} while (action);
} else {
spin_lock(&irq_controller_lock);
desc->mask(irq);
spin_unlock(&irq_controller_lock);
}
}
#endif
int setup_arm_irq(int irq, struct irqaction * new)
{
int shared = 0;
struct irqaction *old, **p;
unsigned long flags;
struct irqdesc *desc;
/*
* Some drivers like serial.c use request_irq() heavily,
* so we have to be careful not to interfere with a
* running system.
*/
if (new->flags & SA_SAMPLE_RANDOM) {
/*
* This function might sleep, we want to call it first,
* outside of the atomic block.
* Yes, this might clear the entropy pool if the wrong
* driver is attempted to be loaded, without actually
* installing a new handler, but is this really a problem,
* only the sysadmin is able to do this.
*/
rand_initialize_irq(irq);
}
/*
* The following block of code has to be executed atomically
*/
desc = irq_desc + irq;
spin_lock_irqsave(&irq_controller_lock, flags);
p = &desc->action;
if ((old = *p) != NULL) {
/* Can't share interrupts unless both agree to */
if (!(old->flags & new->flags & SA_SHIRQ)) {
spin_unlock_irqrestore(&irq_controller_lock, flags);
return -EBUSY;
}
/* add new interrupt at end of irq queue */
do {
p = &old->next;
old = *p;
} while (old);
shared = 1;
}
*p = new;
if (!shared) {
desc->nomask = (new->flags & SA_IRQNOMASK) ? 1 : 0;
desc->probing = 0;
if (!desc->noautoenable) {
desc->enabled = 1;
desc->unmask(irq);
}
}
spin_unlock_irqrestore(&irq_controller_lock, flags);
return 0;
}
/**
* request_irq - allocate an interrupt line
* @irq: Interrupt line to allocate
* @handler: Function to be called when the IRQ occurs
* @irqflags: Interrupt type flags
* @devname: An ascii name for the claiming device
* @dev_id: A cookie passed back to the handler function
*
* This call allocates interrupt resources and enables the
* interrupt line and IRQ handling. From the point this
* call is made your handler function may be invoked. Since
* your handler function must clear any interrupt the board
* raises, you must take care both to initialise your hardware
* and to set up the interrupt handler in the right order.
*
* Dev_id must be globally unique. Normally the address of the
* device data structure is used as the cookie. Since the handler
* receives this value it makes sense to use it.
*
* If your interrupt is shared you must pass a non NULL dev_id
* as this is required when freeing the interrupt.
*
* Flags:
*
* SA_SHIRQ Interrupt is shared
*
* SA_INTERRUPT Disable local interrupts while processing
*
* SA_SAMPLE_RANDOM The interrupt can be used for entropy
*
*/
int request_irq(unsigned int irq, void (*handler)(int, void *, struct pt_regs *),
unsigned long irq_flags, const char * devname, void *dev_id)
{
unsigned long retval;
struct irqaction *action;
if (irq >= NR_IRQS || !irq_desc[irq].valid || !handler ||
(irq_flags & SA_SHIRQ && !dev_id))
return -EINVAL;
action = (struct irqaction *)kmalloc(sizeof(struct irqaction), GFP_KERNEL);
if (!action)
return -ENOMEM;
action->handler = handler;
action->flags = irq_flags;
action->mask = 0;
action->name = devname;
action->next = NULL;
action->dev_id = dev_id;
retval = setup_arm_irq(irq, action);
if (retval)
kfree(action);
return retval;
}
/**
* free_irq - free an interrupt
* @irq: Interrupt line to free
* @dev_id: Device identity to free
*
* Remove an interrupt handler. The handler is removed and if the
* interrupt line is no longer in use by any driver it is disabled.
* On a shared IRQ the caller must ensure the interrupt is disabled
* on the card it drives before calling this function.
*
* This function may be called from interrupt context.
*/
void free_irq(unsigned int irq, void *dev_id)
{
struct irqaction * action, **p;
unsigned long flags;
if (irq >= NR_IRQS || !irq_desc[irq].valid) {
printk(KERN_ERR "Trying to free IRQ%d\n",irq);
#ifdef CONFIG_DEBUG_ERRORS
__backtrace();
#endif
return;
}
spin_lock_irqsave(&irq_controller_lock, flags);
for (p = &irq_desc[irq].action; (action = *p) != NULL; p = &action->next) {
if (action->dev_id != dev_id)
continue;
/* Found it - now free it */
*p = action->next;
kfree(action);
goto out;
}
printk(KERN_ERR "Trying to free free IRQ%d\n",irq);
#ifdef CONFIG_DEBUG_ERRORS
__backtrace();
#endif
out:
spin_unlock_irqrestore(&irq_controller_lock, flags);
}
/* Start the interrupt probing. Unlike other architectures,
* we don't return a mask of interrupts from probe_irq_on,
* but return the number of interrupts enabled for the probe.
* The interrupts which have been enabled for probing is
* instead recorded in the irq_desc structure.
*/
unsigned long probe_irq_on(void)
{
unsigned int i, irqs = 0;
unsigned long delay;
/*
* first snaffle up any unassigned but
* probe-able interrupts
*/
spin_lock_irq(&irq_controller_lock);
for (i = 0; i < NR_IRQS; i++) {
if (!irq_desc[i].valid ||
!irq_desc[i].probe_ok ||
irq_desc[i].action)
continue;
irq_desc[i].probing = 1;
irq_desc[i].triggered = 0;
irq_desc[i].unmask(i);
irqs += 1;
}
spin_unlock_irq(&irq_controller_lock);
/*
* wait for spurious interrupts to mask themselves out again
*/
for (delay = jiffies + HZ/10; time_before(jiffies, delay); )
/* min 100ms delay */;
/*
* now filter out any obviously spurious interrupts
*/
spin_lock_irq(&irq_controller_lock);
for (i = 0; i < NR_IRQS; i++) {
if (irq_desc[i].probing &&
irq_desc[i].triggered) {
irq_desc[i].probing = 0;
irqs -= 1;
}
}
spin_unlock_irq(&irq_controller_lock);
/* now filter out any obviously spurious interrupts */
return irqs;
}
/*
* Possible return values:
* >= 0 - interrupt number
* -1 - no interrupt/many interrupts
*/
int probe_irq_off(unsigned long irqs)
{
unsigned int i;
int irq_found = NO_IRQ;
/*
* look at the interrupts, and find exactly one
* that we were probing has been triggered
*/
spin_lock_irq(&irq_controller_lock);
for (i = 0; i < NR_IRQS; i++) {
if (irq_desc[i].probing &&
irq_desc[i].triggered) {
if (irq_found != NO_IRQ) {
irq_found = NO_IRQ;
goto out;
}
irq_found = i;
}
}
if (irq_found == -1)
irq_found = NO_IRQ;
out:
spin_unlock_irq(&irq_controller_lock);
return irq_found;
}
void __init init_irq_proc(void)
{
}
void __init init_IRQ(void)
{
extern void init_dma(void);
int irq;
for (irq = 0; irq < NR_IRQS; irq++) {
irq_desc[irq].probe_ok = 0;
irq_desc[irq].valid = 0;
irq_desc[irq].noautoenable = 0;
irq_desc[irq].mask_ack = dummy_mask_unmask_irq;
irq_desc[irq].mask = dummy_mask_unmask_irq;
irq_desc[irq].unmask = dummy_mask_unmask_irq;
}
init_arch_irq();
init_dma();
}
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