diff options
| -rw-r--r-- | drivers/tty/serial/Kconfig | 8 | ||||
| -rw-r--r-- | drivers/tty/serial/imx_earlycon.c | 50 |
2 files changed, 58 insertions, 0 deletions
diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig index 7fa2c78d1989..8a0352eb337c 100644 --- a/drivers/tty/serial/Kconfig +++ b/drivers/tty/serial/Kconfig @@ -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 diff --git a/drivers/tty/serial/imx_earlycon.c b/drivers/tty/serial/imx_earlycon.c new file mode 100644 index 000000000000..795606e1a22f --- /dev/null +++ b/drivers/tty/serial/imx_earlycon.c @@ -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"); |