From 699cc4dfd14071e4843e2fde8ce01f09871eb318 Mon Sep 17 00:00:00 2001 From: Fugang Duan Date: Fri, 24 Jul 2020 15:08:15 +0800 Subject: 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/imx_earlycon.c | 50 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 50 insertions(+) create mode 100644 drivers/tty/serial/imx_earlycon.c (limited to 'drivers/tty/serial/imx_earlycon.c') 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"); -- cgit v1.2.3