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authorFugang Duan <fugang.duan@nxp.com>2020-07-24 15:08:15 +0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2020-07-29 17:11:02 +0200
commit699cc4dfd14071e4843e2fde8ce01f09871eb318 (patch)
tree0de192fd5e751a3e4725815fb4da3a146eeaffa1 /drivers/tty
parent0db4f9b91c86bfe9d33e191a31b0150879e2acee (diff)
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 <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>
Diffstat (limited to 'drivers/tty')
-rw-r--r--drivers/tty/serial/Kconfig8
-rw-r--r--drivers/tty/serial/imx_earlycon.c50
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");