linux arm irq : interrupt driver interface
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linux arm irq (4)
4 interrupt driver interface
Author: Yangkai Wang
wang_yangkai@163.com
Coding in 2021/05/16
转载请注明author,出处.
linux version 3.4.39
s5p6818 soc
Cortex-A53 Octa core CPU
Interrupt Controller，GIC400
GIC (Generic Interrupt Controllers), reference:Arm Generic Interrupt Controller Architecture version 2.0,Architecture Specification
GPIO controller，reference:S5P6818 Application Processor Datasheet
-
include <linux/interrupt.h>
static inline int __must_check
request_irq(unsigned int irq, irq_handler_t handler, unsigned long flags,
const char *name, void *dev)
{
return request_threaded_irq(irq, handler, NULL, flags, name, dev);
}
extern void disable_irq_nosync(unsigned int irq);
extern void disable_irq(unsigned int irq);
extern void enable_irq(unsigned int irq);
etc.
example code:
#define CFG_KEYPAD_KEY_OK { PAD_GPIO_B + 31 }
#define CFG_KEYPAD_KEY_OK_CODE { KEY_OK } /* 352 */
/* drivers/input/keyboard/nxp_io_key.c */
...
static int nxp_key_probe(struct platform_device *pdev)
{
...
printk("~~~ %s() gpio:%d, irqno:%d, call request_irq()\\n", \\
__func__, code->io, gpio_to_irq(code->io));
ret = request_irq(gpio_to_irq(code->io), nxp_key_irqhnd,
(IRQF_SHARED | IRQ_TYPE_EDGE_BOTH), pdev->name, code);
if (ret) {
pr_err("fail, gpio[%d] %s request irq...\\n", code->io, pdev->name);
goto err_irq;
}
printk("~~~ %s() gpio:%d, irqno:%d, call disable_irq()\\n", \\
__func__, code->io, gpio_to_irq(code->io));
disable_irq(gpio_to_irq(code->io));
printk("~~~ %s() gpio:%d, irqno:%d, call enable_irq()\\n", \\
__func__, code->io, gpio_to_irq(code->io));
enable_irq(gpio_to_irq(code->io));
printk("~~~ %s() gpio:%d, irqno:%d, call disable_irq()\\n", \\
__func__, code->io, gpio_to_irq(code->io));
disable_irq(gpio_to_irq(code->io));
printk("~~~ %s() gpio:%d, irqno:%d, call enable_irq()\\n", \\
__func__, code->io, gpio_to_irq(code->io));
enable_irq(gpio_to_irq(code->io));
...
}
...
static irqreturn_t nxp_key_irqhnd(int irqno, void *dev_id)
{
struct key_code *code = dev_id;
printk("~~~ %s() irqno:%d\\n", __func__, irqno);
queue_delayed_work(code->kcode_wq,
&code->kcode_work, DELAY_WORK_JIFFIES);
return IRQ_HANDLED;
}
...
log
[ 1.688000] ~~~ nxp_key_probe() gpio:63, irqno:169, call request_irq()
[ 1.692000] gpio_set_type_irq: gpio irq = 169, GPIOB.31, type=0x3
[ 1.692000] reg=0xf001b00c, val=0x00000000
[ 1.692000] reg=0xf001b028, val=0x80000000
[ 1.692000] reg=0xf001b024, val=0x55550002
[ 1.692000] ~~~ __setup_irq() irq:169, desc->depth:1, call irq_startup()
[ 1.692000] ~~~ irq_startup() irq:169, call irq_enable()
[ 1.692000] gpio_irq_enable: gpio irq = 169, GPIOB.31
[ 1.692000] ~~~ gpio_irq_enable() gpio irq:169, GPIOB.31
[ 1.720000] ~~~ nxp_key_probe() gpio:63, irqno:169, call disable_irq()
[ 1.724000] gpio_irq_disable: gpio irq = 169, GPIOB.31
[ 1.724000] ~~~ gpio_irq_disable() gpio irq:169, GPIOB.31
[ 1.736000] ~~~ nxp_key_probe() gpio:63, irqno:169, call enable_irq()
[ 1.740000] ~~~ __enable_irq() do, irq:169, desc->depth:1
[ 1.740000] gpio_irq_enable: gpio irq = 169, GPIOB.31
[ 1.740000] ~~~ gpio_irq_enable() gpio irq:169, GPIOB.31
[ 1.740000] ~~~ __enable_irq() done, irq:169, desc->depth:0
[ 1.760000] ~~~ nxp_key_probe() gpio:63, irqno:169, call disable_irq()
[ 1.764000] gpio_irq_disable: gpio irq = 169, GPIOB.31
[ 1.764000] ~~~ gpio_irq_disable() gpio irq:169, GPIOB.31
[ 1.776000] ~~~ nxp_key_probe() gpio:63, irqno:169, call enable_irq()
[ 1.784000] ~~~ __enable_irq() do, irq:169, desc->depth:1
[ 1.784000] gpio_irq_enable: gpio irq = 169, GPIOB.31
[ 1.784000] ~~~ gpio_irq_enable() gpio irq:169, GPIOB.31
[ 1.784000] ~~~ __enable_irq() done, irq:169, desc->depth:0
[ 1.800000] [1] key io= 63, code= 352
- gpio_to_irq
/* arch/arm/include/asm/gpio.h */
#ifndef _ARCH_ARM_GPIO_H
#define _ARCH_ARM_GPIO_H
#if CONFIG_ARCH_NR_GPIO > 0
#define ARCH_NR_GPios CONFIG_ARCH_NR_GPIO
#endif
/* not all ARM platforms necessarily support this API ... */
#include <mach/gpio.h>
#ifndef __ARM_GPIOLIB_COMPLEX
/* Note: this may rely upon the value of ARCH_NR_GPIOS set in mach/gpio.h */
#include <asm-generic/gpio.h>
/* The trivial gpiolib dispatchers */
#define gpio_get_value __gpio_get_value
#define gpio_set_value __gpio_set_value
#define gpio_cansleep __gpio_cansleep
#endif
/*
* Provide a default gpio_to_irq() which should satisfy every case.
* However, some platforms want to do this differently, so allow them
* to override it.
*/
#ifndef gpio_to_irq
#define gpio_to_irq __gpio_to_irq
#endif
#endif /* _ARCH_ARM_GPIO_H */
/* drivers/gpio/gpiolib.c */
/**
* __gpio_to_irq() - return the IRQ corresponding to a GPIO
* @gpio: gpio whose IRQ will be returned (already requested)
* Context: any
*
* This is used directly or indirectly to implement gpio_to_irq().
* It returns the number of the IRQ signaled by this (input) GPIO,
* or a negative errno.
*/
int __gpio_to_irq(unsigned gpio)
{
struct gpio_chip *chip;
chip = gpio_to_chip(gpio);
return chip->to_irq ? chip->to_irq(chip, gpio - chip->base) : -ENXIO;
}
EXPORT_SYMBOL_GPL(__gpio_to_irq);
/* drivers/gpio/gpio-nxp.c */
static int nxp_gpio_to_irq( struct gpio_chip *chip , unsigned offset )
{
struct nxp_gpio *gpio = GET_GPIO(chip);
unsigned int io = gpio->index * GPIO_NUM_PER_BANK + offset;
/*printk("~~~ %s() offset:%d, io:%d, irq:%d\\n", __func__, \\
offset, io, io + IRQ_GPIO_START);*/
return (io + IRQ_GPIO_START);
}
io number to irq number: fixed io number + IRQ_GPIO_START;
linux 3.4.39 s5p6818, irq number都是固定分配好的；reference:arch/arm/mach-s5p6818/include/mach/s5p6818_irq.h
- request_irq()
/* include/linux/interrupt.h */
static inline int __must_check
request_irq(unsigned int irq, irq_handler_t handler, unsigned long flags,
const char *name, void *dev)
{
return request_threaded_irq(irq, handler, NULL, flags, name, dev);
}
/* kernel/irq/manage.c */
/**
* request_threaded_irq - allocate an interrupt line
* @irq: Interrupt line to allocate
* @handler: Function to be called when the IRQ occurs.
* Primary handler for threaded interrupts
* If NULL and thread_fn != NULL the default
* primary handler is installed
* @thread_fn: Function called from the irq handler thread
* If NULL, no irq thread is created
* @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.
*
* If you want to set up a threaded irq handler for your device
* then you need to supply @handler and @thread_fn. @handler is
* still called in hard interrupt context and has to check
* whether the interrupt originates from the device. If yes it
* needs to disable the interrupt on the device and return
* IRQ_WAKE_THREAD which will wake up the handler thread and run
* @thread_fn. This split handler design is necessary to support
* shared interrupts.
*
* 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_TRIGGER_* Specify active edge(s) or level
*
*/
int request_threaded_irq(unsigned int irq, irq_handler_t handler,
irq_handler_t thread_fn, unsigned long irqflags,
const char *devname, void *dev_id)
{
struct irqaction *action;
struct irq_desc *desc;
int retval;
/*
* Sanity-check: shared interrupts must pass in a real dev-ID,
* otherwise we\'ll have trouble later trying to figure out
* which interrupt is which (messes up the interrupt freeing
* logic etc).
*/
if ((irqflags & IRQF_SHARED) && !dev_id)
return -EINVAL;
desc = irq_to_desc(irq);
if (!desc)
return -EINVAL;
if (!irq_settings_can_request(desc) ||
WARN_ON(irq_settings_is_per_cpu_devid(desc)))
return -EINVAL;
if (!handler) {
if (!thread_fn)
return -EINVAL;
handler = irq_default_primary_handler;
}
action = kzalloc(sizeof(struct irqaction), GFP_KERNEL);
if (!action)
return -ENOMEM;
action->handler = handler;
action->thread_fn = thread_fn;
action->flags = irqflags;
action->name = devname;
action->dev_id = dev_id;
chip_bus_lock(desc);
retval = __setup_irq(irq, desc, action);
chip_bus_sync_unlock(desc);
if (retval)
kfree(action);
#ifdef CONFIG_DEBUG_SHIRQ_FIXME
if (!retval && (irqflags & IRQF_SHARED)) {
/*
* It\'s a shared IRQ -- the driver ought to be prepared for it
* to happen immediately, so let\'s make sure....
* We disable the irq to make sure that a \'real\' IRQ doesn\'t
* run in parallel with our fake.
*/
unsigned long flags;
disable_irq(irq);
local_irq_save(flags);
handler(irq, dev_id);
local_irq_restore(flags);
enable_irq(irq);
}
#endif
return retval;
}
EXPORT_SYMBOL(request_threaded_irq);
alloc struct irqaction *action;
struct irq_desc *desc = irq_to_desc(irq);
retval = __setup_irq(irq, desc, action); / * core ops */
- static int __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
/*
* Internal function to register an irqaction - typically used to
* allocate special interrupts that are part of the architecture.
*/
static int
__setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
{
struct irqaction *old, **old_ptr;
const char *old_name = NULL;
unsigned long flags, thread_mask = 0;
int ret, nested, shared = 0;
cpumask_var_t mask;
if (!desc)
return -EINVAL;
if (desc->irq_data.chip == &no_irq_chip)
return -ENOSYS;
if (!try_module_get(desc->owner))
return -ENODEV;
/*
* Check whether the interrupt nests into another interrupt
* thread.
*/
nested = irq_settings_is_nested_thread(desc);
if (nested) {
if (!new->thread_fn) {
ret = -EINVAL;
goto out_mput;
}
/*
* Replace the primary handler which was provided from
* the driver for non nested interrupt handling by the
* dummy function which warns when called.
*/
new->handler = irq_nested_primary_handler;
} else {
if (irq_settings_can_thread(desc))
irq_setup_forced_threading(new);
}
/*
* Create a handler thread when a thread function is supplied
* and the interrupt does not nest into another interrupt
* thread.
*/
if (new->thread_fn && !nested) {
struct task_struct *t;
t = kthread_create(irq_thread, new, "irq/%d-%s", irq,
new->name);
if (IS_ERR(t)) {
ret = PTR_ERR(t);
goto out_mput;
}
/*
* We keep the reference to the task struct even if
* the thread dies to avoid that the interrupt code
* references an already freed task_struct.
*/
get_task_struct(t);
new->thread = t;
/*
* Tell the thread to set its affinity. This is
* important for shared interrupt handlers as we do
* not invoke setup_affinity() for the secondary
* handlers as everything is already set up. Even for
* interrupts marked with IRQF_NO_BALANCE this is
* correct as we want the thread to move to the cpu(s)
* on which the requesting code placed the interrupt.
*/
set_bit(IRQTF_AFFINITY, &new->thread_flags);
}
if (!alloc_cpumask_var(&mask, GFP_KERNEL)) {
ret = -ENOMEM;
goto out_thread;
}
/*
* The following block of code has to be executed atomically
*/
raw_spin_lock_irqsave(&desc->lock, flags);
old_ptr = &desc->action;
old = *old_ptr;
if (old) {
/*
* Can\'t share interrupts unless both agree to and are
* the same type (level, edge, polarity). So both flag
* fields must have IRQF_SHARED set and the bits which
* set the trigger type must match. Also all must
* agree on ONESHOT.
*/
if (!((old->flags & new->flags) & IRQF_SHARED) ||
((old->flags ^ new->flags) & IRQF_TRIGGER_MASK) ||
((old->flags ^ new->flags) & IRQF_ONESHOT)) {
old_name = old->name;
goto mismatch;
}
/* All handlers must agree on per-cpuness */
if ((old->flags & IRQF_PERCPU) !=
(new->flags & IRQF_PERCPU))
goto mismatch;
/* add new interrupt at end of irq queue */
do {
/*
* Or all existing action->thread_mask bits,
* so we can find the next zero bit for this
* new action.
*/
thread_mask |= old->thread_mask;
old_ptr = &old->next;
old = *old_ptr;
} while (old);
shared = 1;
}
/*
* Setup the thread mask for this irqaction for ONESHOT. For
* !ONESHOT irqs the thread mask is 0 so we can avoid a
* conditional in irq_wake_thread().
*/
if (new->flags & IRQF_ONESHOT) {
/*
* Unlikely to have 32 resp 64 irqs sharing one line,
* but who knows.
*/
if (thread_mask == ~0UL) {
ret = -EBUSY;
goto out_mask;
}
/*
* The thread_mask for the action is or\'ed to
* desc->thread_active to indicate that the
* IRQF_ONESHOT thread handler has been woken, but not
* yet finished. The bit is cleared when a thread
* completes. When all threads of a shared interrupt
* line have completed desc->threads_active becomes
* zero and the interrupt line is unmasked. See
* handle.c:irq_wake_thread() for further information.
*
* If no thread is woken by primary (hard irq context)
* interrupt handlers, then desc->threads_active is
* also checked for zero to unmask the irq line in the
* affected hard irq flow handlers
* (handle_[fasteoi|level]_irq).
*
* The new action gets the first zero bit of
* thread_mask assigned. See the loop above which or\'s
* all existing action->thread_mask bits.
*/
new->thread_mask = 1 << ffz(thread_mask);
}
if (!shared) {
init_waitqueue_head(&desc->wait_for_threads);
/* Setup the type (level, edge polarity) if configured: */
if (new->flags & IRQF_TRIGGER_MASK) {
ret = __irq_set_trigger(desc, irq,
new->flags & IRQF_TRIGGER_MASK);
if (ret)
goto out_mask;
}
desc->istate &= ~(IRQS_AUTODETECT | IRQS_SPURIOUS_DISABLED | \\
IRQS_ONESHOT | IRQS_WAITING);
irqd_clear(&desc->irq_data, IRQD_IRQ_INPROGRESS);
if (new->flags & IRQF_PERCPU) {
irqd_set(&desc->irq_data, IRQD_PER_CPU);
irq_settings_set_per_cpu(desc);
}
if (new->flags & IRQF_ONESHOT)
desc->istate |= IRQS_ONESHOT;
if (irq_settings_can_autoenable(desc)) {
printk("~~~ %s() irq:%u, desc->depth:%d, call irq_startup()\\n", \\
__func__, irq, desc->depth);
irq_startup(desc, true);
/*printk("~~~ %s() irq:%u, desc->depth:%d\\n", \\
__func__, irq, desc->depth);*/
} else {
/* Undo nested disables: */
desc->depth = 1;
printk("~~~ %s() irq:%d, set desc->depth = 1\\n", __func__, irq);
}
/* Exclude IRQ from balancing if requested */
if (new->flags & IRQF_NOBALANCING) {
irq_settings_set_no_balancing(desc);
irqd_set(&desc->irq_data, IRQD_NO_BALANCING);
}
/* Set default affinity mask once everything is setup */
setup_affinity(irq, desc, mask);
} else if (new->flags & IRQF_TRIGGER_MASK) {
unsigned int nmsk = new->flags & IRQF_TRIGGER_MASK;
unsigned int omsk = irq_settings_get_trigger_mask(desc);
if (nmsk != omsk)
/* hope the handler works with current trigger mode */
pr_warning("IRQ %d uses trigger mode %u; requested %u\\n",
irq, nmsk, omsk);
}
new->irq = irq;
*old_ptr = new;
/* Reset broken irq detection when installing new handler */
desc->irq_count = 0;
desc->irqs_unhandled = 0;
/*
* Check whether we disabled the irq via the spurious handler
* before. Reenable it and give it another chance.
*/
if (shared && (desc->istate & IRQS_SPURIOUS_DISABLED)) {
desc->istate &= ~IRQS_SPURIOUS_DISABLED;
__enable_irq(desc, irq, false);
}
raw_spin_unlock_irqrestore(&desc->lock, flags);
/*
* Strictly no need to wake it up, but hung_task complains
* when no hard interrupt wakes the thread up.
*/
if (new->thread)
wake_up_process(new->thread);
register_irq_proc(irq, desc);
new->dir = NULL;
register_handler_proc(irq, new);
free_cpumask_var(mask);
return 0;
mismatch:
#ifdef CONFIG_DEBUG_SHIRQ
if (!(new->flags & IRQF_PROBE_SHARED)) {
printk(KERN_ERR "IRQ handler type mismatch for IRQ %d\\n", irq);
if (old_name)
printk(KERN_ERR "current handler: %s\\n", old_name);
dump_stack();
}
#endif
ret = -EBUSY;
out_mask:
raw_spin_unlock_irqrestore(&desc->lock, flags);
free_cpumask_var(mask);
out_thread:
if (new->thread) {
struct task_struct *t = new->thread;
new->thread = NULL;
kthread_stop(t);
put_task_struct(t);
}
out_mput:
module_put(desc->owner);
return ret;
}
old_ptr = &desc->action;
old = *old_ptr;
if (old) {
/* if irq is share interrupts, and had desc->action */
...
shared = 1;
}
here shared is 0;
if (!shared) {
/* Setup the type (level, edge polarity) if configured: */
if (new->flags & IRQF_TRIGGER_MASK) {
ret = __irq_set_trigger(desc, irq,
new->flags & IRQF_TRIGGER_MASK);
|
/* caller masked out all except trigger mode flags */
ret = chip->irq_set_type(&desc->irq_data, flags);
}
if (irq_settings_can_autoenable(desc)) {
printk("~~~ %s() irq:%u, desc->depth:%d, call irq_startup()\\n", \\
__func__, irq, desc->depth);
irq_startup(desc, true);
|
if (desc->irq_data.chip->irq_startup) {
/* */
} else {
printk("~~~ %s() irq:%u, call irq_enable()\\n", \\
__func__, desc->irq_data.irq);
irq_enable(desc);
/* kernel/irq/chip.c
void irq_enable(struct irq_desc *desc)
{
irq_state_clr_disabled(desc);
if (desc->irq_data.chip->irq_enable)
desc->irq_data.chip->irq_enable(&desc->irq_data);
else
desc->irq_data.chip->irq_unmask(&desc->irq_data);
irq_state_clr_masked(desc);
}
*/
}
}
}
new->irq = irq;
*old_ptr = new;
main operation：
__irq_set_trigger(desc, irq, new->flags & IRQF_TRIGGER_MASK); call chip->irq_set_type(&desc->irq_data, flags);
irq_startup(desc, true); call irq_enable(desc);
and
setup &desc->action; desc->action = new;
- void disable_irq(unsigned int irq)
/* kernel/irq/manage.c */
/**
* disable_irq - disable an irq and wait for completion
* @irq: Interrupt to disable
*
* Disable the selected interrupt line. Enables and Disables are
* nested.
* This function waits for any pending IRQ handlers for this interrupt
* to complete before returning. If you use this function while
* holding a resource the IRQ handler may need you will deadlock.
*
* This function may be called - with care - from IRQ context.
*/
void disable_irq(unsigned int irq)
{
if (!__disable_irq_nosync(irq))
synchronize_irq(irq);
}
EXPORT_SYMBOL(disable_irq);
Enables and Disables are nested.
If you use this function while holding a resource the IRQ handler may need you will deadlock.
/* kernel/irq/manage.c */
static int __disable_irq_nosync(unsigned int irq)
{
unsigned long flags;
struct irq_desc *desc = irq_get_desc_buslock(irq, &flags, IRQ_GET_DESC_CHECK_GLOBAL);
if (!desc)
return -EINVAL;
__disable_irq(desc, irq, false);
irq_put_desc_busunlock(desc, flags);
return 0;
}
/* kernel/irq/manage.c */
void __disable_irq(struct irq_desc *desc, unsigned int irq, bool suspend)
{
if (suspend) {
if (!desc->action || (desc->action->flags & IRQF_NO_SUSPEND))
return;
desc->istate |= IRQS_SUSPENDED;
}
/*printk("~~~ %s() irq:%d, desc->depth:%d\\n", __func__, \\
irq, desc->depth);*/
if (!desc->depth++)
irq_disable(desc);
}
/* kernel/irq/chip.c */
void irq_disable(struct irq_desc *desc)
{
irq_state_set_disabled(desc);
if (desc->irq_data.chip->irq_disable) {
desc->irq_data.chip->irq_disable(&desc->irq_data);
irq_state_set_masked(desc);
}
}
/* kernel/irq/manage.c */
/**
* synchronize_irq - wait for pending IRQ handlers (on other CPUs)
* @irq: interrupt number to wait for
*
* This function waits for any pending IRQ handlers for this interrupt
* to complete before returning. If you use this function while
* holding a resource the IRQ handler may need you will deadlock.
*
* This function may be called - with care - from IRQ context.
*/
void synchronize_irq(unsigned int irq)
{
struct irq_desc *desc = irq_to_desc(irq);
bool inprogress;
if (!desc)
return;
do {
unsigned long flags;
/*
* Wait until we\'re out of the critical section. This might
* give the wrong answer due to the lack of memory barriers.
*/
while (irqd_irq_inprogress(&desc->irq_data))
cpu_relax();
/* Ok, that indicated we\'re done: double-check carefully. */
raw_spin_lock_irqsave(&desc->lock, flags);
inprogress = irqd_irq_inprogress(&desc->irq_data);
raw_spin_unlock_irqrestore(&desc->lock, flags);
/* Oops, that failed? */
} while (inprogress);
/*
* We made sure that no hardirq handler is running. Now verify
* that no threaded handlers are active.
*/
wait_event(desc->wait_for_threads, !atomic_read(&desc->threads_active));
}
EXPORT_SYMBOL(synchronize_irq);
This function waits for any pending IRQ handlers for this interrupt to complete before returning. If you use this function while holding a resource the IRQ handler may need you will deadlock.
- void enable_irq(unsigned int irq)
/* kernel/irq/manage.c */
/**
* enable_irq - enable handling of an irq
* @irq: Interrupt to enable
*
* Undoes the effect of one call to disable_irq(). If this
* matches the last disable, processing of interrupts on this
* IRQ line is re-enabled.
*
* This function may be called from IRQ context only when
* desc->irq_data.chip->bus_lock and desc->chip->bus_sync_unlock are NULL !
*/
void enable_irq(unsigned int irq)
{
unsigned long flags;
struct irq_desc *desc = irq_get_desc_buslock(irq, &flags, IRQ_GET_DESC_CHECK_GLOBAL);
if (!desc)
return;
if (WARN(!desc->irq_data.chip,
KERN_ERR "enable_irq before setup/request_irq: irq %u\\n", irq))
goto out;
__enable_irq(desc, irq, false);
out:
irq_put_desc_busunlock(desc, flags);
}
EXPORT_SYMBOL(enable_irq);
/* kernel/irq/manage.c */
void __enable_irq(struct irq_desc *desc, unsigned int irq, bool resume)
{
if (resume) {
if (!(desc->istate & IRQS_SUSPENDED)) {
if (!desc->action)
return;
if (!(desc->action->flags & IRQF_FORCE_RESUME))
return;
/* Pretend that it got disabled ! */
desc->depth++;
}
desc->istate &= ~IRQS_SUSPENDED;
}
printk("~~~ %s() do, irq:%d, desc->depth:%d\\n", __func__, \\
irq, desc->depth);
switch (desc->depth) {
case 0:
err_out:
WARN(1, KERN_WARNING "Unbalanced enable for IRQ %d\\n", irq);
break;
case 1: {
if (desc->istate & IRQS_SUSPENDED)
goto err_out;
/* Prevent probing on this irq: */
irq_settings_set_noprobe(desc);
irq_enable(desc);
check_irq_resend(desc, irq);
/* fall-through */
}
default:
desc->depth--;
}
printk("~~~ %s() done, irq:%d, desc->depth:%d\\n", __func__, \\
irq, desc->depth);
}
/* kernel/irq/chip.c */
void irq_enable(struct irq_desc *desc)
{
irq_state_clr_disabled(desc);
if (desc->irq_data.chip->irq_enable)
desc->irq_data.chip->irq_enable(&desc->irq_data);
else
desc->irq_data.chip->irq_unmask(&desc->irq_data);
irq_state_clr_masked(desc);
}
disable_irq()中，desc->depth++，只有desc->depth值原来为0，++变为1的这次会去call desc->irq_data.chip->irq_disable(&desc->irq_data);
enable_irq()中，desc->depth--，只有desc->depth值原来为1，--变为0的这次会去call
desc->irq_data.chip->irq_enable(&desc->irq_data); or desc->irq_data.chip->irq_unmask(&desc->irq_data);
- void disable_irq_nosync(unsigned int irq)
/* kernel/irq/manage.c */
static int __disable_irq_nosync(unsigned int irq)
{
unsigned long flags;
struct irq_desc *desc = irq_get_desc_buslock(irq, &flags, IRQ_GET_DESC_CHECK_GLOBAL);
if (!desc)
return -EINVAL;
__disable_irq(desc, irq, false);
irq_put_desc_busunlock(desc, flags);
return 0;
}
/**
* disable_irq_nosync - disable an irq without waiting
* @irq: Interrupt to disable
*
* Disable the selected interrupt line. Disables and Enables are
* nested.
* Unlike disable_irq(), this function does not ensure existing
* instances of the IRQ handler have completed before returning.
*
* This function may be called from IRQ context.
*/
void disable_irq_nosync(unsigned int irq)
{
__disable_irq_nosync(irq);
}
EXPORT_SYMBOL(disable_irq_nosync);
Unlike disable_irq(), this function does not ensure existing instances of the IRQ handler have completed before returning.
This function may be called from IRQ context.
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linux arm irq : interrupt driver interface