1 files changed, 50 insertions, 0 deletions
diff --git a/drivers/tty/serial/imx_earlycon.c b/drivers/tty/serial/imx_earlycon.c
new file mode 100644
index 000000000..7aab38b2b
--- /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, unsigned char 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");