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");
51