On Sat, 2012-12-22 at 23:11 +0800, Woody Wu wrote: > On Fri, Dec 21, 2012 at 01:33:03PM -0800, anish kumar wrote: > > On Fri, 2012-12-21 at 23:34 +0800, Woody Wu wrote: > > > On Thu, Dec 20, 2012 at 10:05:05AM -0800, anish singh wrote: > > > > On Dec 20, 2012 6:30 AM, "Woody Wu" <narkewoody@xxxxxxxxx> wrote: > > > > > > > > > > Hi, List > > > > > > > > > > Where is the Kernel code that handles external interrupts? I want to > > > > > have a look at it but haven't found out where it is. > > > > > > > > > > Actually, I have some basic questions about interrupt handling in Linux. > > > > > 1. After Kernel's ISR received an interrupt, I believe it will invoke a > > > > > handler defined in a device driver if any. But it should be the > > > > > device driver's responsibility or kernel ISR's responsibility to > > > > > clear (or acknowledge) the interrupt? > > > > If the interrupt in question is currently being handled then in > > > > the case of edge triggered interrupt we just mask the interrupt,set it > > > > pending and bail out.Once the interrupt handler completes then we check for > > > > pending interrupt and handle it.In level triggered we don't do that. > > > > Kerenel ISR -this is mixture of core kernel interrupt handling code + your > > > > device driver interrupt handler(if this is chip driver which is supposed to > > > > get one interrupt and is reponsible for calling other interrupt handlers > > > > based on the chip register status then you do explicit masking unmasking > > > > yourself). > > > > If you device driver is a interrupt controller driver then you register > > > > your driver with kernel interrupt handling code and need to write some > > > > callbacks such as .mask,.unmask and so on.This callbacks are called at > > > > appropiate places whenever the interrupt is raised.This interrupt is then > > > > passed to drivers who has requested for this interrupt by calling > > > > request_irq. > > > > > > > > > > 2. My device, an AX88796B network controller, asserting the interrupt > > > > > line in a level-triggered manner. Now I met problem with the device > > > > that > > > > > might caused by the CPU interrupt mode is not set as level-triggered by > > > > > edge trigger. My CPU is Samsung S3C2410, an ARM920T powered one. Does > > > > > anyone know usually where and how should I do this kind of setting? > > > > Just pass the parameter "level triggered" in request_irq in your device > > > > driver. > > > > > > Hi Sign, > > > > > > I searched the interrupt.h for the all the defined flags that I can pass > > > to the request_irq, but there is no a flag looks like "level triggered". > > > Would you tell me what you mean the parameter "level triggered"? > > irq_set_irq_type(info->irq, IRQ_TYPE_LEVEL_LOW) > > > > include/linux/irq.h > > IRQ_TYPE_LEVEL_HIGH - high level triggered > > IRQ_TYPE_LEVEL_LOW - low level triggered > > Thanks. Now I find the function. > > I searched some code about irq in ARM architecure. Some other > people talked about do_IRQ() probabaly is wrong for ARM. There is simply > no that function in ARM. Maybe the do_IRQ in x86 is replaced by > handle_IRQ. arch/arm/kernel/entry-armv.S __irq_svc is called by the arm processor which in turn calls irq_handler macro.I think this is the lowest level handler after which linux interrupt handling takes over. > > For the irq_set_irq_type(), do you think what's the correct place to > call it? Inside my device driver or outside the device driver (probably > in the board definition file)? If that should be called inside a device > driver, should it be the driver probe function or in the open function? > After or before the invocation of request_irq()? irq_set_irq_type() should be called by device driver code not by the board file.It should be called in the probe function AFAIK. > > Sorry for asking too many question. I found the kernel + device driver > irq handling part still not clear to me. You are welcome to ask as many question as you want. > > > > > > > > Thanks. > > > > > > > > > > > > > > > > > > Thanks in advance. > > > > > > > > > > -- > > > > > woody > > > > > I can't go back to yesterday - because I was a different person then. > > > > > > > > > > _______________________________________________ > > > > > Kernelnewbies mailing list > > > > > Kernelnewbies@xxxxxxxxxxxxxxxxx > > > > > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies > > > > > > _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
