BUTTRESS_REG_IRQ_ENABLE
writel(BUTTRESS_IRQS, isp->base + BUTTRESS_REG_IRQ_ENABLE);
writel(0, isp->base + BUTTRESS_REG_IRQ_ENABLE);
isp->base + BUTTRESS_REG_IRQ_ENABLE);
writel(BUTTRESS_IRQS, isp->base + BUTTRESS_REG_IRQ_ENABLE);