interrupt cells on mpc5200

interrupt cells on mpc5200

[Jon Smirl]

mpc5200 interrupts have three cells in the device tree. How are these
interpreted?
Middle one is the interrupt number. Last one seems to always be zero.
What does the first one do, edge/level?

I searched through /Documentation and could find anything about three
cells for interrupts.

I understand the first one for gpio_wkup on interrupt 8. How does a
gpio_wkup generate an interrupt on interrupt 3?

		gpio_wkup: gpio-wkup@c00 {
			compatible = "fsl,mpc5200b-gpio-wkup","fsl,mpc5200-gpio-wkup";
			reg = <0xc00 0x40>;
			interrupts = <0x1 0x8 0x0 0x0 0x3 0x0>;
			interrupt-parent = <&mpc5200_pic>;
			gpio-controller;
			#gpio-cells = <2>;
		};

-- 
Jon Smirl
jonsmirl@gmail.com

Re: interrupt cells on mpc5200

[Wolfgang Grandegger]

Jon Smirl wrote:
> mpc5200 interrupts have three cells in the device tree. How are these
> interpreted?
> Middle one is the interrupt number. Last one seems to always be zero.
> What does the first one do, edge/level?
> 
> I searched through /Documentation and could find anything about three
> cells for interrupts.
> 
> I understand the first one for gpio_wkup on interrupt 8. How does a
> gpio_wkup generate an interrupt on interrupt 3?
> 
> 		gpio_wkup: gpio-wkup@c00 {
> 			compatible = "fsl,mpc5200b-gpio-wkup","fsl,mpc5200-gpio-wkup";
> 			reg = <0xc00 0x40>;
> 			interrupts = <0x1 0x8 0x0 0x0 0x3 0x0>;
> 			interrupt-parent = <&mpc5200_pic>;
> 			gpio-controller;
> 			#gpio-cells = <2>;
> 		};

See
http://lxr.linux.no/linux+v2.6.26.5/Documentation/powerpc/mpc52xx-device-tree-bindings.txt#L263

Wolfgang.

Re: interrupt cells on mpc5200

[Jon Smirl]

On Wed, Sep 10, 2008 at 12:54 PM, Wolfgang Grandegger <wg@grandegger.com> wrote:
> Jon Smirl wrote:
>> mpc5200 interrupts have three cells in the device tree. How are these
>> interpreted?
>> Middle one is the interrupt number. Last one seems to always be zero.
>> What does the first one do, edge/level?
>>
>> I searched through /Documentation and could find anything about three
>> cells for interrupts.
>>
>> I understand the first one for gpio_wkup on interrupt 8. How does a
>> gpio_wkup generate an interrupt on interrupt 3?
>>
>>               gpio_wkup: gpio-wkup@c00 {
>>                       compatible = "fsl,mpc5200b-gpio-wkup","fsl,mpc5200-gpio-wkup";
>>                       reg = <0xc00 0x40>;
>>                       interrupts = <0x1 0x8 0x0 0x0 0x3 0x0>;
>>                       interrupt-parent = <&mpc5200_pic>;
>>                       gpio-controller;
>>                       #gpio-cells = <2>;
>>               };
>
> See
> http://lxr.linux.no/linux+v2.6.26.5/Documentation/powerpc/mpc52xx-device-tree-bindings.txt#L263

Why was I too blind to see that file? So there must be someway to turn
a gpio_wkup into a critical interrupt which causes the interrupt 3
which is a feature I don't need.

Any hints on a good way to measure the length of pulses? They are
between 500us and 2ms long. I was thinking of using an interrupt on
the leading edge, starting a timer, and then flipping the gpio to
cause an interrupt on the trailing edge. I don't need extreme
accuracy.

-- 
Jon Smirl
jonsmirl@gmail.com