From 699cc4dfd14071e4843e2fde8ce01f09871eb318 Mon Sep 17 00:00:00 2001 From: Fugang Duan Date: Fri, 24 Jul 2020 15:08:15 +0800 Subject: [PATCH] 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 Link: https://lore.kernel.org/r/20200724070815.11445-3-fugang.duan@nxp.com Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/Kconfig | 8 +++++ drivers/tty/serial/imx_earlycon.c | 50 +++++++++++++++++++++++++++++++ 2 files changed, 58 insertions(+) create mode 100644 drivers/tty/serial/imx_earlycon.c 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 +#include +#include +#include +#include +#include +#include +#include + +#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");