On Fri, 15 Apr 2011, Abhijeet Dharmapurikar wrote: > Some drivers need to know what the status of the interrupt line is. > This is especially true for drivers that register a handler with > IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING and in the handler they > need to know which edge transition it was invoked for. What's the purpose of this? How is that going to be used? > The irq_read_line callback in the chip allows the controller to provide > the real time status of this line. Controllers that can read the status > of an interrupt line should implement this by doing necessary > hardware reads and return the logical state of the line. > > Interrupt controllers based on the slow bus architecture should conduct > the transaction in this callback. The genirq code will call the chip's > bus lock prior to calling irq_read_line. Obviously since the transaction > would be completed before returning from irq_read_line it need not do > any transactions in the bus unlock call. > > Drivers need to be aware whether the interrupt controller is a slow bus > and call read_irq_line in proper context. > > Signed-off-by: Abhijeet Dharmapurikar <adharmap@xxxxxxxxxxxxxx> > --- > include/linux/interrupt.h | 1 + > include/linux/irq.h | 2 ++ > kernel/irq/manage.c | 25 +++++++++++++++++++++++++ > 3 files changed, 28 insertions(+), 0 deletions(-) > > diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h > index 59b72ca..0722576 100644 > --- a/include/linux/interrupt.h > +++ b/include/linux/interrupt.h > @@ -337,6 +337,7 @@ static inline void enable_irq_lockdep_irqrestore(unsigned int irq, unsigned long > > /* IRQ wakeup (PM) control: */ > extern int irq_set_irq_wake(unsigned int irq, unsigned int on); > +extern int irq_read_line(unsigned int irq); > > #ifndef CONFIG_GENERIC_HARDIRQS_NO_COMPAT That hunk does not apply. > /* Please do not use: Use the replacement functions instead */ > diff --git a/include/linux/irq.h b/include/linux/irq.h > index 2a375a7..52198b6 100644 > --- a/include/linux/irq.h > +++ b/include/linux/irq.h > @@ -298,6 +298,7 @@ static inline void irqd_clr_chained_irq_inprogress(struct irq_data *d) > * @irq_retrigger: resend an IRQ to the CPU > * @irq_set_type: set the flow type (IRQ_TYPE_LEVEL/etc.) of an IRQ > * @irq_set_wake: enable/disable power-management wake-on of an IRQ > + * @irq_read_line: return the current value on the irq line > * @irq_bus_lock: function to lock access to slow bus (i2c) chips > * @irq_bus_sync_unlock:function to sync and unlock slow bus (i2c) chips > * @irq_cpu_online: configure an interrupt source for a secondary CPU > @@ -324,6 +325,7 @@ struct irq_chip { > int (*irq_retrigger)(struct irq_data *data); > int (*irq_set_type)(struct irq_data *data, unsigned int flow_type); > int (*irq_set_wake)(struct irq_data *data, unsigned int on); > + int (*irq_read_line)(struct irq_data *data); > > void (*irq_bus_lock)(struct irq_data *data); > void (*irq_bus_sync_unlock)(struct irq_data *data); > diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c > index 12a80fd..6667052 100644 > --- a/kernel/irq/manage.c > +++ b/kernel/irq/manage.c > @@ -518,6 +518,31 @@ int irq_set_irq_wake(unsigned int irq, unsigned int on) > } > EXPORT_SYMBOL(irq_set_irq_wake); > > +/** > + * irq_read_line - read the value on an irq line > + * @irq: Interrupt number representing a hardware line > + * > + * This function may be called from IRQ context only when > + * desc->chip->bus_lock and desc->chip->bus_sync_unlock are NULL ! > + */ > +int irq_read_line(unsigned int irq) > +{ > + struct irq_desc *desc = irq_to_desc(irq); > + unsigned long flags; > + int val; Please use irq_get_desc_buslock() > + if (!desc || !desc->irq_data.chip->irq_read_line) > + return -EINVAL; > + > + chip_bus_lock(desc); > + raw_spin_lock_irqsave(&desc->lock, flags); > + val = desc->irq_data.chip->irq_read_line(&desc->irq_data); > + raw_spin_unlock_irqrestore(&desc->lock, flags); > + chip_bus_sync_unlock(desc); > + return val; > +} > +EXPORT_SYMBOL(irq_read_line); EXPORT_SYMBOL_GPL() please. Thanks, tglx -- To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html