serial: nulldev: Add nulldev serial driver
Some device the serial console's initialization cannot run early during the boot process. Hence, nulldev serial device is helpful on that situation. For example, if the serial module was implemented in FPGA. Serial initialization is prohibited to run until the FPGA was programmed. This commit is to adding nulldev serial driver. This will allows the default console to be specified as a nulldev. Signed-off-by: Joe Hershberger <joe.hershberger@ni.com> Signed-off-by: Keng Soon Cheah <keng.soon.cheah@ni.com> Cc: Chen Yee Chew <chen.yee.chew@ni.com>
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@ -414,6 +414,13 @@ config MXC_UART
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If you have a machine based on a Motorola IMX CPU you
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can enable its onboard serial port by enabling this option.
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config NULLDEV_SERIAL
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bool "Null serial device"
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help
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Select this to enable null serial device support. A null serial
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device merely acts as a placeholder for a serial device and does
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nothing for all it's operation.
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config PIC32_SERIAL
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bool "Support for Microchip PIC32 on-chip UART"
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depends on DM_SERIAL && MACH_PIC32
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@ -49,6 +49,7 @@ obj-$(CONFIG_BCM283X_MU_SERIAL) += serial_bcm283x_mu.o
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obj-$(CONFIG_MSM_SERIAL) += serial_msm.o
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obj-$(CONFIG_MVEBU_A3700_UART) += serial_mvebu_a3700.o
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obj-$(CONFIG_MPC8XX_CONS) += serial_mpc8xx.o
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obj-$(CONFIG_NULLDEV_SERIAL) += serial_nulldev.o
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ifndef CONFIG_SPL_BUILD
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obj-$(CONFIG_USB_TTY) += usbtty.o
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48
drivers/serial/serial_nulldev.c
Normal file
48
drivers/serial/serial_nulldev.c
Normal file
@ -0,0 +1,48 @@
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/*
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* Copyright (c) 2015 National Instruments
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*
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* SPDX-License-Identifier: GPL-2.0+
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*/
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#include <common.h>
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#include <dm.h>
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#include <serial.h>
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static int nulldev_serial_setbrg(struct udevice *dev, int baudrate)
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{
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return 0;
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}
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static int nulldev_serial_getc(struct udevice *dev)
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{
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return -EAGAIN;
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}
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static int nulldev_serial_input(struct udevice *dev)
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{
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return 0;
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}
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static int nulldev_serial_putc(struct udevice *dev, const char ch)
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{
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return 0;
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}
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static const struct udevice_id nulldev_serial_ids[] = {
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{ .compatible = "nulldev-serial" },
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{ }
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};
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const struct dm_serial_ops nulldev_serial_ops = {
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.putc = nulldev_serial_putc,
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.getc = nulldev_serial_getc,
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.setbrg = nulldev_serial_setbrg,
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};
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U_BOOT_DRIVER(serial_nulldev) = {
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.name = "serial_nulldev",
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.id = UCLASS_SERIAL,
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.of_match = nulldev_serial_ids,
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.ops = &nulldev_serial_ops,
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};
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