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tty: serial: imx: add imx earlycon driver

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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>
This commit is contained in:
Fugang Duan 2020-07-24 15:08:15 +08:00 committed by Greg Kroah-Hartman
parent 0db4f9b91c
commit 699cc4dfd1
2 changed files with 58 additions and 0 deletions
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8
drivers/tty/serial/Kconfig
View File

@ -515,6 +515,14 @@ config SERIAL_IMX_CONSOLE
"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

50
drivers/tty/serial/imx_earlycon.c Normal file
View File

@ -0,0 +1,50 @@
// 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");