1 // SPDX-License-Identifier: GPL-2.0+ 2 /* 3 * Copyright 2020 NXP 4 */ 5 6 #include <linux/module.h> 7 #include <linux/ioport.h> 8 #include <linux/init.h> 9 #include <linux/serial_core.h> 10 #include <linux/serial.h> 11 #include <linux/delay.h> 12 #include <linux/of.h> 13 #include <linux/io.h> 14 15 #define URTX0 0x40 /* Transmitter Register */ 16 #define UTS_TXFULL (1<<4) /* TxFIFO full */ 17 #define IMX21_UTS 0xb4 /* UART Test Register on all other i.mx*/ 18 19 static void imx_uart_console_early_putchar(struct uart_port *port, int ch) 20 { 21 while (readl_relaxed(port->membase + IMX21_UTS) & UTS_TXFULL) 22 cpu_relax(); 23 24 writel_relaxed(ch, port->membase + URTX0); 25 } 26 27 static void imx_uart_console_early_write(struct console *con, const char *s, 28 unsigned count) 29 { 30 struct earlycon_device *dev = con->data; 31 32 uart_console_write(&dev->port, s, count, imx_uart_console_early_putchar); 33 } 34 35 static int __init 36 imx_console_early_setup(struct earlycon_device *dev, const char *opt) 37 { 38 if (!dev->port.membase) 39 return -ENODEV; 40 41 dev->con->write = imx_uart_console_early_write; 42 43 return 0; 44 } 45 OF_EARLYCON_DECLARE(ec_imx6q, "fsl,imx6q-uart", imx_console_early_setup); 46 OF_EARLYCON_DECLARE(ec_imx21, "fsl,imx21-uart", imx_console_early_setup); 47 48 MODULE_AUTHOR("NXP"); 49 MODULE_DESCRIPTION("IMX earlycon driver"); 50 MODULE_LICENSE("GPL"); 51