/*
* linux/arch/arm/kernel/irq.c
*
* Copyright (C) 1992 Linus Torvalds
* Modifications for ARM processor Copyright (C) 1995-2000 Russell King.
* 'Borrowed' for ARM26 and (C) 2003 Ian Molton.
*
* 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/module.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 <linux/seq_file.h>
#include <linux/errno.h>
#include <asm/irq.h>
#include <asm/system.h>
#include <asm/irqchip.h>
//FIXME - this ought to be in a header IMO
void __init arc_init_irq(void);
/*
* 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.
*
* FIXME 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 DEFINE_SPINLOCK(irq_controller_lock);
struct irqdesc irq_desc[NR_IRQS];
/*
* Dummy mask/unmask handler
*/
void dummy_mask_unmask_irq(unsigned int irq)
{
}
void do_bad_IRQ(unsigned int irq, struct irqdesc *desc, struct pt_regs *regs)
{
irq_err_count += 1;
printk(KERN_ERR "IRQ: spurious interrupt %d\n", irq);
}
static struct irqchip bad_chip = {
.ack = dummy_mask_unmask_irq,
.mask = dummy_mask_unmask_irq,
.unmask = dummy_mask_unmask_irq,
};
static struct irqdesc bad_irq_desc = {
.chip = &bad_chip,
.handle = do_bad_IRQ,
.depth = 1,
};
/**
* disable_irq - disable an irq and wait for completion
* @irq: Interrupt to disable
*
* Disable the selected interrupt line. We do this lazily.
*
* This function may be called from IRQ context.
*/
void disable_irq(unsigned int irq)
{
struct irqdesc *desc = irq_desc + irq;
unsigned long flags;
spin_lock_irqsave(&irq_controller_lock, flags);
if (!desc->depth++)
desc->enabled = 0;
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.
* Note that this may call the interrupt handler, so you may
* get unexpected results if you hold IRQs disabled.
*
* This function may be called from IRQ context.
*/
void enable_irq(unsigned int irq)
{
struct irqdesc *desc = irq_desc + irq;
unsigned long flags;
int pending = 0;
spin_lock_irqsave(&irq_controller_lock, flags);
if (unlikely(!desc->depth)) {
printk("enable_irq(%u) unbalanced from %p\n", irq,
__builtin_return_address(0)); //FIXME bum addresses reported - why?
} else if (!--desc->depth) {
desc->probing = 0;
desc->enabled = 1;
desc->chip->unmask(irq);
pending = desc->pending;
desc->pending = 0;
/*
* If the interrupt was waiting to be processed,
* retrigger it.
*/
if (pending)
desc->chip->rerun(irq);
}
spin_unlock_irqrestore(&irq_controller_lock, flags);
}
int show_interrupts(struct seq_file *p, void *v)
{
int i = *(loff_t *) v;
struct irqaction * action;
if (i < NR_IRQS) {
action = irq_desc[i].action;
if (!action)
goto out;
seq_printf(p, "%3d: %10u ", i, kstat_irqs(i));
seq_printf(p, " %s", action->name);
for (action = action->next; action; action = action->next) {
seq_printf(p, ", %s", action->name);
}
seq_putc(p, '\n');
} else if (i == NR_IRQS) {
show_fiq_list(p, v);
seq_printf(p, "Err: %10lu\n", irq_err_count);
}
out:
return 0;
}
/*
* 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 int 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);
return 1;
}
} else {
desc->lck_cnt = 0;
desc->lck_pc = instruction_pointer(regs);
desc->lck_jif = jiffies;
}
return 0;
}
static void
__do_irq(unsigned int irq, struct irqaction *action, struct pt_regs *regs)
{
unsigned int status;
int ret;
spin_unlock(&irq_controller_lock);
if (!(action->flags & IRQF_DISABLED))
local_irq_enable();
status = 0;
do {
ret = action->handler(irq, action->dev_id, regs);
if (ret == IRQ_HANDLED)
status |= action->flags;
action = action->next;
} while (action);
if (status & IRQF_SAMPLE_RANDOM)
add_interrupt_randomness(irq);
spin_lock_irq(&irq_controller_lock);
}
/*
* This is for software-decoded IRQs. The caller is expected to
* handle the ack, clear, mask and unmask issues.
*/
void
do_simple_IRQ(unsigned int irq, struct irqdesc *desc, struct pt_regs *regs)
{
struct irqaction *action;
const int cpu = smp_processor_id();
desc->triggered = 1;
kstat_cpu(cpu).irqs[irq]++;
action = desc->action;
if (action)
__do_irq(irq, desc->action, regs);
}
/*
* Most edge-triggered IRQ implementations seem to take a broken
* approach to this. Hence the complexity.
*/
void
do_edge_IRQ(unsigned int irq, struct irqdesc *desc, struct pt_regs *regs)
{
const int cpu = smp_processor_id();
desc->triggered = 1;
/*
* If we're currently running this IRQ, or its disabled,
* we shouldn't process the IRQ. Instead, turn on the
* hardware masks.
*/
if (unlikely(desc->running || !desc->enabled))
goto running;
/*
* Acknowledge and clear the IRQ, but don't mask it.
*/
desc->chip->ack(irq);
/*
* Mark the IRQ currently in progress.
*/
desc->running = 1;
kstat_cpu(cpu).irqs[irq]++;
do {
struct irqaction *action;
action = desc->action;
if (!action)
break;
if (desc->pending && desc->enabled) {
desc->pending = 0;
desc->chip->unmask(irq);
}
__do_irq(irq, action, regs);
} while (desc->pending);
desc->running = 0;
/*
* If we were disabled or freed, shut down the handler.
*/
if (likely(desc->action && !check_irq_lock(desc, irq, regs)))
return;
running:
/*
* We got another IRQ while this one was masked or
* currently running. Delay it.
*/
desc->pending = 1;
desc->chip->mask(irq);
desc->chip->ack(irq);
}
/*
* Level-based IRQ handler. Nice and simple.
*/
void
do_level_IRQ(unsigned int irq, struct irqdesc *desc, struct pt_regs *regs)
{
struct irqaction *action;
const int cpu = smp_processor_id();
desc->triggered = 1;
/*
* Acknowledge, clear _AND_ disable the interrupt.
*/
desc->chip->ack(irq);
if (likely(desc->enabled)) {
kstat_cpu(cpu).irqs[irq]++;
/*
* Return with this interrupt masked if no action
*/
action = desc->action;
if (action) {
__do_irq(irq, desc->action, regs);
if (likely(desc->enabled &&
!check_irq_lock(desc, irq, regs)))
desc->chip->unmask(irq);
}
}
}
/*
* do_IRQ handles all hardware IRQ's. Decoded IRQs should not
* come via this function. Instead, they should provide their
* own 'handler'
*/
asmlinkage void asm_do_IRQ(int irq, struct pt_regs *regs)
{
struct irqdesc *desc = irq_desc + irq;
/*
* Some hardware gives randomly wrong interrupts. Rather
* than crashing, do something sensible.
*/
if (irq >= NR_IRQS)
desc = &bad_irq_desc;
irq_enter();
spin_lock(&irq_controller_lock);
desc->handle(irq, desc, regs);
spin_unlock(&irq_controller_lock);
irq_exit();
}
void __set_irq_handler(unsigned int irq, irq_handler_t handle, int is_chained)
{
struct irqdesc *desc;
unsigned long flags;
if (irq >= NR_IRQS) {
printk(KERN_ERR "Trying to install handler for IRQ%d\n", irq);
return;
}
if (handle == NULL)
handle = do_bad_IRQ;
desc = irq_desc + irq;
if (is_chained && desc->chip == &bad_chip)
printk(KERN_WARNING "Trying to install chained handler for IRQ%d\n", irq);
spin_lock_irqsave(&irq_controller_lock, flags);
if (handle == do_bad_IRQ) {
desc->chip->mask(irq);
desc->chip->ack(irq);
desc->depth = 1;
desc->enabled = 0;
}
desc->handle = handle;
if (handle != do_bad_IRQ && is_chained) {
desc->valid = 0;
desc->probe_ok = 0;
desc->depth = 0;
desc->chip->unmask(irq);
}
spin_unlock_irqrestore(&irq_controller_lock, flags);
}
void set_irq_chip(unsigned int irq, struct irqchip *chip)
{
struct irqdesc *desc;
unsigned long flags;
if (irq >= NR_IRQS) {
printk(KERN_ERR "Trying to install chip for IRQ%d\n", irq);
return;
}
if (chip == NULL)
chip = &bad_chip;
desc = irq_desc + irq;
spin_lock_irqsave(&irq_controller_lock, flags);
desc->chip = chip;
spin_unlock_irqrestore(&irq_controller_lock, flags);
}
int set_irq_type(unsigned int irq, unsigned int type)
{
struct irqdesc *desc;
unsigned long flags;
int ret = -ENXIO;
if (irq >= NR_IRQS) {
printk(KERN_ERR "Trying to set irq type for IRQ%d\n", irq);
return -ENODEV;
}
desc = irq_desc + irq;
if (desc->chip->type) {
spin_lock_irqsave(&irq_controller_lock, flags);
ret = desc->chip->type(irq, type);
spin_unlock_irqrestore(&irq_controller_lock, flags);
}
return ret;
}
void set_irq_flags(unsigned int irq, unsigned int iflags)
{
struct irqdesc *desc;
unsigned long flags;
if (irq >= NR_IRQS) {
printk(KERN_ERR "Trying to set irq flags for IRQ%d\n", irq);
return;
}
desc = irq_desc + irq;
spin_lock_irqsave(&irq_controller_lock, flags);
desc->valid = (iflags & IRQF_VALID) != 0;
desc->probe_ok = (iflags & IRQF_PROBE) != 0;
desc->noautoenable = (iflags & IRQF_NOAUTOEN) != 0;
spin_unlock_irqrestore(&irq_controller_lock, flags);
}
int setup_irq(unsigned 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 & IRQF_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 & IRQF_SHARED)) {
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->probing = 0;
desc->running = 0;
desc->pending = 0;
desc->depth = 1;
if (!desc->noautoenable) {
desc->depth = 0;
desc->enabled = 1;
desc->chip->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:
*
* IRQF_SHARED Interrupt is shared
*
* IRQF_DISABLED Disable local interrupts while processing
*
* IRQF_SAMPLE_RANDOM The interrupt can be used for entropy
*
*/
//FIXME - handler used to return void - whats the significance of the change?
int request_irq(unsigned int irq, irqreturn_t (*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 & IRQF_SHARED && !dev_id))
return -EINVAL;
action = kmalloc(sizeof(struct irqaction), GFP_KERNEL);
if (!action)
return -ENOMEM;
action->handler = handler;
action->flags = irq_flags;
cpus_clear(action->mask);
action->name = devname;
action->next = NULL;
action->dev_id = dev_id;
retval = setup_irq(irq, action);
if (retval)
kfree(action);
return retval;
}
EXPORT_SYMBOL(request_irq);
/**
* 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);
}
EXPORT_SYMBOL(free_irq);
/* 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].probe_ok || irq_desc[i].action)
continue;
irq_desc[i].probing = 1;
irq_desc[i].triggered = 0;
if (irq_desc[i].chip->type)
irq_desc[i].chip->type(i, IRQT_PROBE);
irq_desc[i].chip->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);
return irqs;
}
EXPORT_SYMBOL(probe_irq_on);
/*
* 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;
}
EXPORT_SYMBOL(probe_irq_off);
void __init init_irq_proc(void)
{
}
void __init init_IRQ(void)
{
struct irqdesc *desc;
extern void init_dma(void);
int irq;
for (irq = 0, desc = irq_desc; irq < NR_IRQS; irq++, desc++)
*desc = bad_irq_desc;
arc_init_irq();
init_dma();
}
