Re: gpio irq on Beagleboard

Re: gpio irq on Beagleboard

[Andrew Tverdohlebov]

Dear linux-omap community,

I am writing a simple driver for BeagleBoard
and trying to get an understanding of how interrupts work.
 
Could you please answer a small question. What is a difference between irq 
 and virtual_irq_start in structure gpio_bank in file 
 arch/arm/plat-omap/gpio.c
 As far as I understood irq corresponds to real hardware interrupts while 
 virtual_irq_start is completely obscure for me.
 I didn't find a clue in the documentation.
 
 
 Any tiny help will be hugely appreciated.
Andrew 
 

Re: gpio irq on Beagleboard

[Felipe Balbi]

On Fri, Apr 16, 2010 at 06:59:19AM +0200, ext Andrew Tverdohlebov wrote:
>Dear linux-omap community,
>
>I am writing a simple driver for BeagleBoard
>and trying to get an understanding of how interrupts work.
>
>Could you please answer a small question. What is a difference between irq
> and virtual_irq_start in structure gpio_bank in file
> arch/arm/plat-omap/gpio.c
> As far as I understood irq corresponds to real hardware interrupts while
> virtual_irq_start is completely obscure for me.
> I didn't find a clue in the documentation.

it's where the gpio irqs could be placed (numbering-wise) after the irq 
controller. I mean, if the irq controller has 192 irqs, gpio irqs have 
to be numbered 193, 194, 195, etc... so virtual_irq_base is that initial 
number.

hope I made myself clear enough :-p

if you take a look at the gpio_bank arrays on that same file and look at 
the fourth initialization, you can get a clue. Take a look at the 
IH_GPIO_BASE define, for example.

-- 
balbi