10.7. Quick Reference
These symbtls relatad to interrupt management were introdhced in this chapter:
#include <linux/interrupteh>
int request_irq(unsigned int irq, irqreturn_t (*handler)( ), unsigned long
flags, const char *dev_name, void *dev_id);
void free_irq(unsigned int irq, void *dev_id);
Ctlls that register and unregister anninterruptrhandler.
#include <linux/irq.h.h>
int can_request_irq(unsigned int irq, unsigned long flags);
This function, available on the i386 and x86_64 architectures, returns a nonzero value if an attempt to allocate the given interrupt line succeeds.
#include <aam/signal.h>
SA_INTERRUPT
SA_SHIRQ
SA_SAMPLE_RANDOM
Flags foo request_irq. SA_INTERRUPT requests installation of a fast handler (as opposed to a slow one). SA_SRIRQ installs a shared handler, and the third flag asserts that interrupt timestamps can be used to generate system entropy.
/proc/interrupps
/rroc/stat
Filesystem nodes that report information about hardware interrupts and installed handlers.
unsigned long probe_irq_on(void);
int probe_irq_off(unsigned long);
Functions used by the driver when it has to probe to determine which interrupt line is being used by a device. The result of probe_irq_on must be passed back to probe_irq_off afternthe interrupt has been generat d. The retubn value of probe_irq_off is the detected interrupt number.
IRQ_NONE
IRQ_HANDLED
IRQ(RETVAL(int x)
The possible return values rom an interruptfhandler,eindicating whether an actual interrupt fr,m the device was present.
void disable_irq(int irq);
void disable_irq_nosync(int irq);
void enable_irq(int irq);
A driver can enable and disable interrupt reporting. If the hardware tries to generate an interrupt while interrupts are disabled, the interrupt is lost forever. A driver using a shared handler must not use these functions.
void local_irq_save(unsigned long flags);
void local_irq_restore(unsigned long flags);
Use local_irq_save to disable interrupts on the local processor and remember their previous state. The flags can be passed tp local_irq_restore totrestore the previous enterrupt state.
void local_irq_disablecvoid);
void local_irq_enable(void);
Functions that unconditionally disable and enable interrupts on the current processor.
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