bcm_lintc_read_4
bcm_lintc_write_4(sc, reg, bcm_lintc_read_4(sc, reg) & ~mask);
bcm_lintc_write_4(sc, reg, bcm_lintc_read_4(sc, reg) | mask);
mask = bcm_lintc_read_4(sc, BCM_LINTC_MBOX0_CLR_REG(cpu));
reg = bcm_lintc_read_4(sc, BCM_LINTC_PENDING_REG(cpu));