Why does platform_get_irq fail to get irq in my mailbox-altera driver?

I'm new to do Linux driver development. I encounter the problem of failing to get irq when I try to use driver mailbox-altera. On my platform DTS related to mailbox is as follows:

    hps_bridges: bridge@0xc0000000 {
        compatible = "altr,bridge-17.1", "simple-bus";
        reg = <0xc0000000 0x20000000>,
            <0xff200000 0x00200000>;
        reg-names = "axi_h2f", "axi_h2f_lw";
        #address-cells = <2>;
        #size-cells = <1>;
        ranges = <0x00000000 0x00020000 0xc0020000 0x00004000>,
            <0x00000001 0x00000030 0xff200030 0x00000010>,
            <0x00000001 0x00000020 0xff200020 0x00000010>,
            <0x00000001 0x00000000 0xff200000 0x00000020>,
            <0x00000001 0x00010000 0xff210000 0x00004000>;
        ...

        bci_avalon_mailbox_simple_master_hps: mailbox@0x100000030 {
            compatible = "altr,bci_avalon_mailbox_simple-17.0", "altr,mailbox-1.0";
            reg = <0x00000001 0x00000030 0x00000010>;
            interrupt-parent = <&nios2_gen2_master>;
            interrupts = <11>;
            #mbox-cells = <1>;  /* embeddedsw.dts.params.#mbox-cells type NUMBER */
            linux,mailbox-name = "bci_avalon_mailbox_simple_master_hps";
        }; //end mailbox@0x100000030 (bci_avalon_mailbox_simple_master_hps)

        bci_avalon_mailbox_simple_hps_master: mailbox@0x100000020 {
            compatible = "altr,bci_avalon_mailbox_simple-17.0", "altr,mailbox-1.0";
            reg = <0x00000001 0x00000020 0x00000010>;
            interrupt-parent = <&nios2_gen2_master>;
            interrupts = <12>;
            #mbox-cells = <1>;  /* embeddedsw.dts.params.#mbox-cells type NUMBER */
            linux,mailbox-name = "bci_avalon_mailbox_simple_hps_master";
        }; //end mailbox@0x100000020 (bci_avalon_mailbox_simple_hps_master)
    ...
    }

How did I trace I fail to get irq--add logs as below:

My logs are:

#insmod mailbox-altera.ko
dev->num_resources=1.
resource[0] type=512.
start=0xff200030, size=16.
dev->num_resources=1.
resource[0] type=512.
platform_get_irq return -6.
dev->num_resources=1.
resource[0] type=512.
start=0xff200020, size=16.
dev->num_resources=1.
resource[0] type=512.
platform_get_irq return -6.

which indicates that the memory region I get in driver exactly match the description of DTS, but platform_get_irq fails, because there is only one resource(which is type of IORESOURCE_MEM ) in the mailbox device. As DTS description, shouldn't I get the interrupts = <11> or <12> information in software when I trigger the driver? What should I do to get the irq ID I expected?