How to get the irq flags from the dts file

[Wei Ni <wni-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>]

Hi, all
I'm working on tegra wlan upstream issue.
The tegra board use the Broadcom 4329 as wlan device, and the driver is
the brcmfmac. 

This wlan driver support out-band-interrupt (OOB), I want to add DT
support to use this OOB.
I can add following lines in the dts file to create platform device and
pass the interrupt resource to the driver.

wlan {
        compatible = "broadcome, brcmf_sdio_pd";
        interrupt-parten = <&gpio>;
        interrupts = <144, 0x04>; /* IRQF_TRIGGER_HIGH */
};

In the wlan driver, it will use platform_get_resource() to get the
res->irq, res->flags, the irq number is right, but the flags will be
IORESOURCE_IRQ, not the 0x04 (IRQF_TRIGGER_HIGH).
The wlan driver wish this flags include the IRQF_TRGGER_* information,
and it will use this flags to configure other hw settings. If it is
wrong, the wlan can't work.

I checked drivers/of/irq.c, in function of_irq_to_resource(), it will
set r->flags = IORESOURCE_IRQ directly, not read the flags from the dtb
file. And I didn't find any of_xx api to get this flags.

How can I get this flags, does anyone has suggestion?

Thanks.
Wei.