STM32F4_RCC_BDCR
val = readl(base + STM32F4_RCC_BDCR);
writel(val | BIT(16), base + STM32F4_RCC_BDCR);
writel(val & ~BIT(16), base + STM32F4_RCC_BDCR);
base + STM32F4_RCC_BDCR, 0, 1, 0, &stm32f4_clk_lock);
base + STM32F4_RCC_BDCR, 15, 8, 0, &stm32f4_clk_lock);