+
+#ifdef CONFIG_DEBUG_UART_BOARD_INIT
+void board_debug_uart_init(void)
+{
+#define GRF_BASE 0xff770000
+#define GPIO0_BASE 0xff720000
+#define PMUGRF_BASE 0xff320000
+ struct rk3399_grf_regs * const grf = (void *)GRF_BASE;
+#ifdef CONFIG_TARGET_CHROMEBOOK_BOB
+ struct rk3399_pmugrf_regs * const pmugrf = (void *)PMUGRF_BASE;
+ struct rockchip_gpio_regs * const gpio = (void *)GPIO0_BASE;
+#endif
+
+#if defined(CONFIG_DEBUG_UART_BASE) && (CONFIG_DEBUG_UART_BASE == 0xff180000)
+ /* Enable early UART0 on the RK3399 */
+ rk_clrsetreg(&grf->gpio2c_iomux,
+ GRF_GPIO2C0_SEL_MASK,
+ GRF_UART0BT_SIN << GRF_GPIO2C0_SEL_SHIFT);
+ rk_clrsetreg(&grf->gpio2c_iomux,
+ GRF_GPIO2C1_SEL_MASK,
+ GRF_UART0BT_SOUT << GRF_GPIO2C1_SEL_SHIFT);
+#else
+# ifdef CONFIG_TARGET_CHROMEBOOK_BOB
+ rk_setreg(&grf->io_vsel, 1 << 0);
+
+ /*
+ * Let's enable these power rails here, we are already running the SPI
+ * Flash based code.
+ */
+ spl_gpio_output(gpio, GPIO(BANK_B, 2), 1); /* PP1500_EN */
+ spl_gpio_set_pull(&pmugrf->gpio0_p, GPIO(BANK_B, 2), GPIO_PULL_NORMAL);
+
+ spl_gpio_output(gpio, GPIO(BANK_B, 4), 1); /* PP3000_EN */
+ spl_gpio_set_pull(&pmugrf->gpio0_p, GPIO(BANK_B, 4), GPIO_PULL_NORMAL);
+#endif /* CONFIG_TARGET_CHROMEBOOK_BOB */
+
+ /* Enable early UART2 channel C on the RK3399 */
+ rk_clrsetreg(&grf->gpio4c_iomux,
+ GRF_GPIO4C3_SEL_MASK,
+ GRF_UART2DGBC_SIN << GRF_GPIO4C3_SEL_SHIFT);
+ rk_clrsetreg(&grf->gpio4c_iomux,
+ GRF_GPIO4C4_SEL_MASK,
+ GRF_UART2DBGC_SOUT << GRF_GPIO4C4_SEL_SHIFT);
+ /* Set channel C as UART2 input */
+ rk_clrsetreg(&grf->soc_con7,
+ GRF_UART_DBG_SEL_MASK,
+ GRF_UART_DBG_SEL_C << GRF_UART_DBG_SEL_SHIFT);
+#endif
+}
+#endif