linux/drivers/tty/serial/imx_earlycon.c
Fugang Duan 699cc4dfd1 tty: serial: imx: add imx earlycon driver
Split imx earlycon driver from imx serial driver "imx.c" as
separated driver. imx serial driver can be built as module,
but earlycon driver only support build in.

Signed-off-by: Fugang Duan <fugang.duan@nxp.com>
Link: https://lore.kernel.org/r/20200724070815.11445-3-fugang.duan@nxp.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-07-29 17:11:02 +02:00

51 lines
1.3 KiB
C

// 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");