my %rpi_v2_gpio_p1 = (
    SPI_CLK  => Device::BCM2835::RPI_V2_GPIO_P1_03,
    SPI_CS  => Device::BCM2835::RPI_V2_GPIO_P1_05,
    SPI_MOSI  => Device::BCM2835::RPI_V2_GPIO_P1_07,
    SPI_MISO  => Device::BCM2835::RPI_V2_GPIO_P1_07,
    ...,
);

##</code><code>##

... globals.h:
#define PIN_RTC_IRQ 2

...Firmware.ino:
#if RADIODUINO_BOARD_REVISION < 2
    // RTC PIN uses internal pullup resistor
    pinMode(PIN_RTC_IRQ, INPUT_PULLUP);
#else
    // REV B and up already have an external pullup
    pinMode(PIN_RTC_IRQ, INPUT);
#endif

... alarms.cpp:
attachInterrupt(digitalPinToInterrupt(PIN_RTC_IRQ), RTCIRQ, FALLING);

##</code><code>##

#if RADIODUINO_BOARD_REVISION < 4
#define PIN_RTC_IRQ 2
#else
#define PIN_RTC_IRQ 3
#endif

##</code><code>##

$ fgrep PIN_RTC_IRQ *
alarms.cpp:    attachInterrupt(digitalPinToInterrupt(PIN_RTC_IRQ), RTCIRQ, FALLING);
Firmware.ino:    pinMode(PIN_RTC_IRQ, INPUT_PULLUP);
Firmware.ino:    pinMode(PIN_RTC_IRQ, INPUT);
globals.h:#define PIN_RTC_IRQ 2