# SPDX-License-Identifier: GPL-2.0 # # The 8250/16550 serial drivers. You shouldn't be in this list unless # you somehow have an implicit or explicit dependency on SERIAL_8250. # config SERIAL_8250 tristate "8250/16550 and compatible serial support" depends on !S390 select SERIAL_CORE select SERIAL_MCTRL_GPIO if GPIOLIB help This selects whether you want to include the driver for the standard serial ports. The standard answer is Y. People who might say N here are those that are setting up dedicated Ethernet WWW/FTP servers, or users that have one of the various bus mice instead of a serial mouse and don't intend to use their machine's standard serial port for anything. To compile this driver as a module, choose M here: the module will be called 8250. [WARNING: Do not compile this driver as a module if you are using non-standard serial ports, since the configuration information will be lost when the driver is unloaded. This limitation may be lifted in the future.] BTW1: If you have a mouseman serial mouse which is not recognized by the X window system, try running gpm first. BTW2: If you intend to use a software modem (also called Winmodem) under Linux, forget it. These modems are crippled and require proprietary drivers which are only available under Windows. Most people will say Y or M here, so that they can use serial mice, modems and similar devices connecting to the standard serial ports. config SERIAL_8250_DEPRECATED_OPTIONS bool "Support 8250_core.* kernel options (DEPRECATED)" depends on SERIAL_8250 default y help In 3.7 we renamed 8250 to 8250_core by mistake, so now we have to accept kernel parameters in both forms like 8250_core.nr_uarts=4 and 8250.nr_uarts=4. We now renamed the module back to 8250, but if anybody noticed in 3.7 and changed their userspace we still have to keep the 8250_core.* options around until they revert the changes they already did. If 8250 is built as a module, this adds 8250_core alias instead. If you did not notice yet and/or you have userspace from pre-3.7, it is safe (and recommended) to say N here. config SERIAL_8250_PNP bool "8250/16550 PNP device support" if EXPERT depends on SERIAL_8250 && PNP default y help This builds standard PNP serial support. You may be able to disable this feature if you only need legacy serial support. config SERIAL_8250_16550A_VARIANTS bool "Support for variants of the 16550A serial port" depends on SERIAL_8250 default !X86 help The 8250 driver can probe for many variants of the venerable 16550A serial port. Doing so takes additional time at boot. On modern systems, especially those using serial only for a simple console, you can say N here. config SERIAL_8250_FINTEK bool "Support for Fintek F81216A LPC to 4 UART RS485 API" depends on SERIAL_8250 help Selecting this option will add support for the RS485 capabilities of the Fintek F81216A LPC to 4 UART. If this option is not selected the device will be configured as a standard 16550A serial port. If unsure, say N. config SERIAL_8250_CONSOLE bool "Console on 8250/16550 and compatible serial port" depends on SERIAL_8250=y select SERIAL_CORE_CONSOLE select SERIAL_EARLYCON help If you say Y here, it will be possible to use a serial port as the system console (the system console is the device which receives all kernel messages and warnings and which allows logins in single user mode). This could be useful if some terminal or printer is connected to that serial port. Even if you say Y here, the currently visible virtual console (/dev/tty0) will still be used as the system console by default, but you can alter that using a kernel command line option such as "console=ttyS1". (Try "man bootparam" or see the documentation of your boot loader (grub or lilo or loadlin) about how to pass options to the kernel at boot time.) If you don't have a VGA card installed and you say Y here, the kernel will automatically use the first serial line, /dev/ttyS0, as system console. You can set that using a kernel command line option such as "console=uart8250,io,0x3f8,9600n8" "console=uart8250,mmio,0xff5e0000,115200n8". and it will switch to normal serial console when the corresponding port is ready. "earlycon=uart8250,io,0x3f8,9600n8" "earlycon=uart8250,mmio,0xff5e0000,115200n8". it will not only setup early console. If unsure, say N. config SERIAL_8250_GSC tristate depends on SERIAL_8250 && PARISC default SERIAL_8250 config SERIAL_8250_DMA bool "DMA support for 16550 compatible UART controllers" if EXPERT depends on SERIAL_8250 && DMADEVICES=y default SERIAL_8250 help This builds DMA support that can be used with 8250/16650 compatible UART controllers that support DMA signaling. config SERIAL_8250_PCI tristate "8250/16550 PCI device support" depends on SERIAL_8250 && PCI default SERIAL_8250 help This builds standard PCI serial support. You may be able to disable this feature if you only need legacy serial support. Saves about 9K. Note that serial ports on NetMos 9835 Multi-I/O cards are handled by the parport_serial driver, enabled with CONFIG_PARPORT_SERIAL. config SERIAL_8250_EXAR tristate "8250/16550 Exar/Commtech PCI/PCIe device support" depends on SERIAL_8250_PCI default SERIAL_8250 help This builds support for XR17C1xx, XR17V3xx and some Commtech 422x PCIe serial cards that are not covered by the more generic SERIAL_8250_PCI option. config SERIAL_8250_HP300 tristate depends on SERIAL_8250 && HP300 default SERIAL_8250 config SERIAL_8250_CS tristate "8250/16550 PCMCIA device support" depends on PCMCIA && SERIAL_8250 help Say Y here to enable support for 16-bit PCMCIA serial devices, including serial port cards, modems, and the modem functions of multi-function Ethernet/modem cards. (PCMCIA- or PC-cards are credit-card size devices often used with laptops.) To compile this driver as a module, choose M here: the module will be called serial_cs. If unsure, say N. config SERIAL_8250_MEN_MCB tristate "MEN MCB UART device support" depends on MCB && SERIAL_8250 help This enables support for FPGA based UARTs found on many MEN boards. This driver enables support for the 16z025, 16z057 and 16z125 UARTs. To compile this driver as a module, chose M here: the module will be called 8250_men_mcb. config SERIAL_8250_NR_UARTS int "Maximum number of 8250/16550 serial ports" depends on SERIAL_8250 default "4" help Set this to the number of serial ports you want the driver to support. This includes any ports discovered via ACPI or PCI enumeration and any ports that may be added at run-time via hot-plug, or any ISA multi-port serial cards. config SERIAL_8250_RUNTIME_UARTS int "Number of 8250/16550 serial ports to register at runtime" depends on SERIAL_8250 range 0 SERIAL_8250_NR_UARTS default "4" help Set this to the maximum number of serial ports you want the kernel to register at boot time. This can be overridden with the module parameter "nr_uarts", or boot-time parameter 8250.nr_uarts config SERIAL_8250_EXTENDED bool "Extended 8250/16550 serial driver options" depends on SERIAL_8250 help If you wish to use any non-standard features of the standard "dumb" driver, say Y here. This includes HUB6 support, shared serial interrupts, special multiport support, support for more than the four COM 1/2/3/4 boards, etc. Note that the answer to this question won't directly affect the kernel: saying N will just cause the configurator to skip all the questions about serial driver options. If unsure, say N. config SERIAL_8250_MANY_PORTS bool "Support more than 4 legacy serial ports" depends on SERIAL_8250_EXTENDED && !IA64 help Say Y here if you have dumb serial boards other than the four standard COM 1/2/3/4 ports. This may happen if you have an AST FourPort, Accent Async, Boca (read the Boca mini-HOWTO, available from ), or other custom serial port hardware which acts similar to standard serial port hardware. If you only use the standard COM 1/2/3/4 ports, you can say N here to save some memory. You can also say Y if you have an "intelligent" multiport card such as Digiboards, etc. # # Multi-port serial cards # config SERIAL_8250_FOURPORT tristate "Support Fourport cards" depends on SERIAL_8250 != n && ISA && SERIAL_8250_MANY_PORTS help Say Y here if you have an AST FourPort serial board. To compile this driver as a module, choose M here: the module will be called 8250_fourport. config SERIAL_8250_ACCENT tristate "Support Accent cards" depends on SERIAL_8250 != n && ISA && SERIAL_8250_MANY_PORTS help Say Y here if you have an Accent Async serial board. To compile this driver as a module, choose M here: the module will be called 8250_accent. config SERIAL_8250_ASPEED_VUART tristate "Aspeed Virtual UART" depends on SERIAL_8250 depends on OF depends on MFD_SYSCON depends on ARCH_ASPEED || COMPILE_TEST select REGMAP help If you want to use the virtual UART (VUART) device on Aspeed BMC platforms, enable this option. This enables the 16550A- compatible device on the local LPC bus, giving a UART device with no physical RS232 connections. config SERIAL_8250_BOCA tristate "Support Boca cards" depends on SERIAL_8250 != n && ISA && SERIAL_8250_MANY_PORTS help Say Y here if you have a Boca serial board. Please read the Boca mini-HOWTO, available from To compile this driver as a module, choose M here: the module will be called 8250_boca. config SERIAL_8250_EXAR_ST16C554 tristate "Support Exar ST16C554/554D Quad UART" depends on SERIAL_8250 != n && ISA && SERIAL_8250_MANY_PORTS help The Uplogix Envoy TU301 uses this Exar Quad UART. If you are tinkering with your Envoy TU301, or have a machine with this UART, say Y here. To compile this driver as a module, choose M here: the module will be called 8250_exar_st16c554. config SERIAL_8250_HUB6 tristate "Support Hub6 cards" depends on SERIAL_8250 != n && ISA && SERIAL_8250_MANY_PORTS help Say Y here if you have a HUB6 serial board. To compile this driver as a module, choose M here: the module will be called 8250_hub6. # # Misc. options/drivers. # config SERIAL_8250_SHARE_IRQ bool "Support for sharing serial interrupts" depends on SERIAL_8250_EXTENDED help Some serial boards have hardware support which allows multiple dumb serial ports on the same board to share a single IRQ. To enable support for this in the serial driver, say Y here. config SERIAL_8250_DETECT_IRQ bool "Autodetect IRQ on standard ports (unsafe)" depends on SERIAL_8250_EXTENDED help Say Y here if you want the kernel to try to guess which IRQ to use for your serial port. This is considered unsafe; it is far better to configure the IRQ in a boot script using the setserial command. If unsure, say N. config SERIAL_8250_RSA bool "Support RSA serial ports" depends on SERIAL_8250_EXTENDED help Say Y here if you have a IODATA RSA-DV II/S ISA card and would like to use its >115kbps speeds. You will need to provide module parameter "probe_rsa", or boot-time parameter 8250.probe_rsa with I/O addresses of this card then. If you don't have such card, or if unsure, say N. config SERIAL_8250_DWLIB bool config SERIAL_8250_ACORN tristate "Acorn expansion card serial port support" depends on ARCH_ACORN && SERIAL_8250 help If you have an Atomwide Serial card or Serial Port card for an Acorn system, say Y to this option. The driver can handle 1, 2, or 3 port cards. If unsure, say N. config SERIAL_8250_BCM2835AUX tristate "BCM2835 auxiliar mini UART support" depends on ARCH_BCM2835 || COMPILE_TEST depends on SERIAL_8250 && SERIAL_8250_SHARE_IRQ help Support for the BCM2835 auxiliar mini UART. Features and limitations of the UART are Registers are similar to 16650 registers, set bits in the control registers that are unsupported are ignored and read back as 0 7/8 bit operation with 1 start and 1 stop bit 8 symbols deep fifo for rx and tx SW controlled RTS and SW readable CTS Clock rate derived from system clock Uses 8 times oversampling (compared to 16 times for 16650) Missing break detection (but break generation) Missing framing error detection Missing parity bit Missing receive time-out interrupt Missing DCD, DSR, DTR and RI signals If unsure, say N. config SERIAL_8250_FSL bool "Freescale 16550 UART support" if COMPILE_TEST && !(PPC || ARM || ARM64) depends on SERIAL_8250_CONSOLE default PPC || ARM || ARM64 help Selecting this option enables a workaround for a break-detection erratum for Freescale 16550 UARTs in the 8250 driver. It also enables support for ACPI enumeration. config SERIAL_8250_DW tristate "Support for Synopsys DesignWare 8250 quirks" depends on SERIAL_8250 select SERIAL_8250_DWLIB help Selecting this option will enable handling of the extra features present in the Synopsys DesignWare APB UART. config SERIAL_8250_EM tristate "Support for Emma Mobile integrated serial port" depends on SERIAL_8250 && HAVE_CLK depends on ARM || COMPILE_TEST help Selecting this option will add support for the integrated serial port hardware found on the Emma Mobile line of processors. If unsure, say N. config SERIAL_8250_IOC3 tristate "SGI IOC3 8250 UART support" depends on SERIAL_8250 depends on SGI_MFD_IOC3 || COMPILE_TEST select SERIAL_8250_EXTENDED select SERIAL_8250_SHARE_IRQ help Enable this if you have a SGI Origin or Octane machine. This module provides basic serial support by directly driving the UART chip behind the IOC3 device on those systems. Maximum baud speed is 38400bps using this driver. config SERIAL_8250_RT288X bool "Ralink RT288x/RT305x/RT3662/RT3883 serial port support" depends on SERIAL_8250 default y if MIPS_ALCHEMY || SOC_RT288X || SOC_RT305X || SOC_RT3883 || SOC_MT7620 help Selecting this option will add support for the alternate register layout used by Ralink RT288x/RT305x, Alchemy Au1xxx, and some others. If unsure, say N. config SERIAL_8250_OMAP tristate "Support for OMAP internal UART (8250 based driver)" depends on SERIAL_8250 depends on ARCH_OMAP2PLUS || ARCH_K3 || COMPILE_TEST help If you have a machine based on an Texas Instruments OMAP CPU you can enable its onboard serial ports by enabling this option. This driver uses ttyS instead of ttyO. config SERIAL_8250_OMAP_TTYO_FIXUP bool "Replace ttyO with ttyS" depends on SERIAL_8250_OMAP=y && SERIAL_8250_CONSOLE default y help This option replaces the "console=ttyO" argument with the matching ttyS argument if the user did not specified it on the command line. This ensures that the user can see the kernel output during boot which he wouldn't see otherwise. The getty has still to be configured for ttyS instead of ttyO regardless of this option. This option is intended for people who "automatically" enable this driver without knowing that this driver requires a different console= argument. If you read this, please keep this option disabled and instead update your kernel command line. If you prepare a kernel for a distribution or other kind of larger user base then you probably want to keep this option enabled. Otherwise people might complain about a not booting kernel because the serial console remains silent in case they forgot to update the command line. config SERIAL_8250_LPC18XX tristate "NXP LPC18xx/43xx serial port support" depends on SERIAL_8250 && OF && (ARCH_LPC18XX || COMPILE_TEST) default ARCH_LPC18XX help If you have a LPC18xx/43xx based board and want to use the serial port, say Y to this option. If unsure, say Y. config SERIAL_8250_MT6577 tristate "Mediatek serial port support" depends on SERIAL_8250 depends on ARCH_MEDIATEK || COMPILE_TEST help If you have a Mediatek based board and want to use the serial port, say Y to this option. If unsure, say N. config SERIAL_8250_UNIPHIER tristate "Support for UniPhier on-chip UART" depends on SERIAL_8250 depends on ARCH_UNIPHIER || COMPILE_TEST help If you have a UniPhier based board and want to use the on-chip serial ports, say Y to this option. If unsure, say N. config SERIAL_8250_INGENIC tristate "Support for Ingenic SoC serial ports" depends on SERIAL_8250 depends on OF_FLATTREE depends on MIPS || COMPILE_TEST help If you have a system using an Ingenic SoC and wish to make use of its UARTs, say Y to this option. If unsure, say N. config SERIAL_8250_LPSS tristate "Support for serial ports on Intel LPSS platforms" default SERIAL_8250 depends on SERIAL_8250 && PCI depends on X86 || COMPILE_TEST select SERIAL_8250_DWLIB select DW_DMAC_CORE if SERIAL_8250_DMA select DW_DMAC_PCI if (SERIAL_8250_DMA && X86_INTEL_LPSS) select RATIONAL help Selecting this option will enable handling of the extra features present on the UART found on various Intel platforms such as: - Intel Baytrail SoC - Intel Braswell SoC - Intel Quark X1000 SoC config SERIAL_8250_MID tristate "Support for serial ports on Intel MID platforms" default SERIAL_8250 depends on SERIAL_8250 && PCI depends on X86 || COMPILE_TEST select HSU_DMA if SERIAL_8250_DMA select HSU_DMA_PCI if (HSU_DMA && X86_INTEL_MID) select RATIONAL help Selecting this option will enable handling of the extra features present on the UART found on Intel Medfield SOC and various other Intel platforms. config SERIAL_8250_PXA tristate "PXA serial port support" depends on SERIAL_8250 depends on ARCH_PXA || ARCH_MMP || COMPILE_TEST help If you have a machine based on an Intel XScale PXA2xx CPU you can enable its onboard serial ports by enabling this option. The option is applicable to both devicetree and legacy boards, and early console is part of its support. config SERIAL_8250_TEGRA tristate "8250 support for Tegra serial ports" default SERIAL_8250 depends on SERIAL_8250 depends on ARCH_TEGRA || COMPILE_TEST help Select this option if you have machine with an NVIDIA Tegra SoC and wish to enable 8250 serial driver for the Tegra serial interfaces. config SERIAL_8250_BCM7271 tristate "Broadcom 8250 based serial port" depends on SERIAL_8250 && (ARCH_BRCMSTB || COMPILE_TEST) default ARCH_BRCMSTB help If you have a Broadcom STB based board and want to use the enhanced features of the Broadcom 8250 based serial port, including DMA support and high accuracy BAUD rates, say Y to this option. If unsure, say N. config SERIAL_OF_PLATFORM tristate "Devicetree based probing for 8250 ports" depends on SERIAL_8250 && OF help This option is used for all 8250 compatible serial ports that are probed through devicetree, including Open Firmware based PowerPC systems and embedded systems on architectures using the flattened device tree format.