[meta-xilinx] Linux/bare-metal AMP interrupt routing

[Nathan Rossi]

On Wed, Jun 10, 2015 at 3:27 AM, Edward Wingate <edwingate8 at gmail.com> wrote:
> I got a bare-metal application running on CPU1 with Linux on CPU0,
> using zynq_remoteproc as described in ug978.
>
> One thing I don't understand in ug978
> (http://www.xilinx.com/support/documentation/sw_manuals/petalinux2014_2/ug978-petalinux-zynq-amp.pdf)
> is the interrupts property in the remoteproc device tree entry, pg.
> 23:
>
> test: remoteproc-test at 0 {
>     compatible = "xlnx,zynq, remoteproc";
>     reg = < 0x0 0x10000000 >;
>     interrupt-parent = <&ps7_scugic_0>;
>     interrupts = < 0 37 4 0 38 4 >;
>     firmware = "freertos";
>     ipino = <6>;
>     vring0 = <2>;
>     vring1 = <3>;
> } ;
>
> It says "The interrupts property allows the consumption of interrupts
> from Linux to be routed for FreeRTOS, in this case the TTC1 interrupts
> are routed."  But 37 and 38 are XPS_PMU0_INT_ID and XPS_PMU1_INT_ID,
> the performance monitoring units, not TTC1.  What am I missing here?
>
> I want to route FPGA2 interrupt (63) instead, so I have < 0 63 4 > for
> interrupts property, but it doesn't seem to be working.  I set up the
> interrupt handler on my CPU1 bare-metal application for
> XPS_FPGA2_INT_ID, but it doesn't trigger.  Are there other config
> items I need to change?

So the trick is that the kernel maps the SGI or PPI (aka the first 32
interrupts) separately to the Shared Peripheral Interrupts, so
everything is shifted 32 interrupts down. e.g. TTC1's interrupt "69"
is 69-32 = 37. So for interrupt 63 (as describe in the TRM) the
interrupt number in the device tree is 31.

For reference the first cell of the interrupts property describes
whether it is SPI or SGI/PPI. Have a quick read of the GIC's binding
doc: http://lxr.free-electrons.com/source/Documentation/devicetree/bindings/arm/gic.txt#L25

Regards,
Nathan

>
> Thanks for your help.
> --
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