imx_earlycon.c (1295B)
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 19static void imx_uart_console_early_putchar(struct uart_port *port, unsigned char 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 27static 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 35static int __init 36imx_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} 45OF_EARLYCON_DECLARE(ec_imx6q, "fsl,imx6q-uart", imx_console_early_setup); 46OF_EARLYCON_DECLARE(ec_imx21, "fsl,imx21-uart", imx_console_early_setup); 47 48MODULE_AUTHOR("NXP"); 49MODULE_DESCRIPTION("IMX earlycon driver"); 50MODULE_LICENSE("GPL");