GRER_OFFSET
grer = readl_relaxed(c->regbase + GRER_OFFSET) & ~c->irq_mask;
writel_relaxed(grer, c->regbase + GRER_OFFSET);
grer = readl_relaxed(base + GRER_OFFSET) & ~GPIO_bit(gpio);
writel_relaxed(grer, base + GRER_OFFSET);
writel_relaxed(0, c->regbase + GRER_OFFSET);
c->saved_grer = readl_relaxed(c->regbase + GRER_OFFSET);
writel_relaxed(c->saved_grer, c->regbase + GRER_OFFSET);