MAILBOX_INTMASK_REG
writel_relaxed(~0, mbox->mbox_base + MAILBOX_INTMASK_REG);
mask = readl_relaxed(mbox->mbox_base + MAILBOX_INTMASK_REG);
writel_relaxed(mask, mbox->mbox_base + MAILBOX_INTMASK_REG);
mask = readl_relaxed(mbox->mbox_base + MAILBOX_INTMASK_REG);
writel_relaxed(mask, mbox->mbox_base + MAILBOX_INTMASK_REG);