tty: serial: imx: add imx earlycon driver

	  "console=ttymxc0". (Try "man bootparam" or see the documentation of

	  your bootloader about how to pass options to the kernel at boot time.)

config SERIAL_IMX_EARLYCON

	bool "Earlycon on IMX serial port"

	depends on OF

	select SERIAL_EARLYCON

	help

	  If you have enabled the earlycon on the Freescale IMX

	  CPU you can make it the earlycon by answering Y to this option.

config SERIAL_UARTLITE

	tristate "Xilinx uartlite serial port support"

	depends on HAS_IOMEM

// SPDX-License-Identifier: GPL-2.0+

/*

 * Copyright 2020 NXP

 */

#include <linux/module.h>

#include <linux/ioport.h>

#include <linux/init.h>

#include <linux/serial_core.h>

#include <linux/serial.h>

#include <linux/delay.h>

#include <linux/of.h>

#include <linux/io.h>

#define URTX0 0x40 /* Transmitter Register */

#define UTS_TXFULL (1<<4) /* TxFIFO full */

#define IMX21_UTS 0xb4 /* UART Test Register on all other i.mx*/

static void imx_uart_console_early_putchar(struct uart_port *port, int ch)

{

	while (readl_relaxed(port->membase + IMX21_UTS) & UTS_TXFULL)

		cpu_relax();

	writel_relaxed(ch, port->membase + URTX0);

}

static void imx_uart_console_early_write(struct console *con, const char *s,

					 unsigned count)

{

	struct earlycon_device *dev = con->data;

	uart_console_write(&dev->port, s, count, imx_uart_console_early_putchar);

}

static int __init

imx_console_early_setup(struct earlycon_device *dev, const char *opt)

{

	if (!dev->port.membase)

		return -ENODEV;

	dev->con->write = imx_uart_console_early_write;

	return 0;

}

OF_EARLYCON_DECLARE(ec_imx6q, "fsl,imx6q-uart", imx_console_early_setup);

OF_EARLYCON_DECLARE(ec_imx21, "fsl,imx21-uart", imx_console_early_setup);

MODULE_AUTHOR("NXP");

MODULE_DESCRIPTION("IMX earlycon driver");

MODULE_LICENSE("GPL");