tjh.dev
Linux kernel mirror (for testing)
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linux
1# SPDX-License-Identifier: GPL-2.0
2#
3# The 8250/16550 serial drivers. You shouldn't be in this list unless
4# you somehow have an implicit or explicit dependency on SERIAL_8250.
5#
6
7config SERIAL_8250
8 tristate "8250/16550 and compatible serial support"
9 depends on !S390
10 select SERIAL_CORE
11 select SERIAL_MCTRL_GPIO if GPIOLIB
12 help
13 This selects whether you want to include the driver for the standard
14 serial ports. The standard answer is Y. People who might say N
15 here are those that are setting up dedicated Ethernet WWW/FTP
16 servers, or users that have one of the various bus mice instead of a
17 serial mouse and don't intend to use their machine's standard serial
18 port for anything.
19
20 To compile this driver as a module, choose M here: the
21 module will be called 8250.
22 [WARNING: Do not compile this driver as a module if you are using
23 non-standard serial ports, since the configuration information will
24 be lost when the driver is unloaded. This limitation may be lifted
25 in the future.]
26
27 BTW1: If you have a mouseman serial mouse which is not recognized by
28 the X window system, try running gpm first.
29
30 BTW2: If you intend to use a software modem (also called Winmodem)
31 under Linux, forget it. These modems are crippled and require
32 proprietary drivers which are only available under Windows.
33
34 Most people will say Y or M here, so that they can use serial mice,
35 modems and similar devices connecting to the standard serial ports.
36
37config SERIAL_8250_DEPRECATED_OPTIONS
38 bool "Support 8250_core.* kernel options (DEPRECATED)"
39 depends on SERIAL_8250
40 default y
41 help
42 In 3.7 we renamed 8250 to 8250_core by mistake, so now we have to
43 accept kernel parameters in both forms like 8250_core.nr_uarts=4 and
44 8250.nr_uarts=4. We now renamed the module back to 8250, but if
45 anybody noticed in 3.7 and changed their userspace we still have to
46 keep the 8250_core.* options around until they revert the changes
47 they already did.
48
49 If 8250 is built as a module, this adds 8250_core alias instead.
50
51 If you did not notice yet and/or you have userspace from pre-3.7, it
52 is safe (and recommended) to say N here.
53
54config SERIAL_8250_PNP
55 bool "8250/16550 PNP device support" if EXPERT
56 depends on SERIAL_8250 && PNP
57 default y
58 help
59 This builds standard PNP serial support. You may be able to
60 disable this feature if you only need legacy serial support.
61
62config SERIAL_8250_16550A_VARIANTS
63 bool "Support for variants of the 16550A serial port"
64 depends on SERIAL_8250
65 default !X86
66 help
67 The 8250 driver can probe for many variants of the venerable 16550A
68 serial port. Doing so takes additional time at boot.
69
70 On modern systems, especially those using serial only for a simple
71 console, you can say N here.
72
73config SERIAL_8250_FINTEK
74 bool "Support for Fintek F81216A LPC to 4 UART RS485 API"
75 depends on SERIAL_8250
76 help
77 Selecting this option will add support for the RS485 capabilities
78 of the Fintek F81216A LPC to 4 UART.
79
80 If this option is not selected the device will be configured as a
81 standard 16550A serial port.
82
83 If unsure, say N.
84
85config SERIAL_8250_CONSOLE
86 bool "Console on 8250/16550 and compatible serial port"
87 depends on SERIAL_8250=y
88 select SERIAL_CORE_CONSOLE
89 select SERIAL_EARLYCON
90 help
91 If you say Y here, it will be possible to use a serial port as the
92 system console (the system console is the device which receives all
93 kernel messages and warnings and which allows logins in single user
94 mode). This could be useful if some terminal or printer is connected
95 to that serial port.
96
97 Even if you say Y here, the currently visible virtual console
98 (/dev/tty0) will still be used as the system console by default, but
99 you can alter that using a kernel command line option such as
100 "console=ttyS1". (Try "man bootparam" or see the documentation of
101 your boot loader (grub or lilo or loadlin) about how to pass options
102 to the kernel at boot time.)
103
104 If you don't have a VGA card installed and you say Y here, the
105 kernel will automatically use the first serial line, /dev/ttyS0, as
106 system console.
107
108 You can set that using a kernel command line option such as
109 "console=uart8250,io,0x3f8,9600n8"
110 "console=uart8250,mmio,0xff5e0000,115200n8".
111 and it will switch to normal serial console when the corresponding
112 port is ready.
113 "earlycon=uart8250,io,0x3f8,9600n8"
114 "earlycon=uart8250,mmio,0xff5e0000,115200n8".
115 it will not only setup early console.
116
117 If unsure, say N.
118
119config SERIAL_8250_GSC
120 tristate
121 depends on SERIAL_8250 && GSC
122 default SERIAL_8250
123
124config SERIAL_8250_DMA
125 bool "DMA support for 16550 compatible UART controllers" if EXPERT
126 depends on SERIAL_8250 && DMADEVICES=y
127 default SERIAL_8250
128 help
129 This builds DMA support that can be used with 8250/16650
130 compatible UART controllers that support DMA signaling.
131
132config SERIAL_8250_PCI
133 tristate "8250/16550 PCI device support"
134 depends on SERIAL_8250 && PCI
135 default SERIAL_8250
136 help
137 This builds standard PCI serial support. You may be able to
138 disable this feature if you only need legacy serial support.
139 Saves about 9K.
140 Note that serial ports on NetMos 9835 Multi-I/O cards are handled
141 by the parport_serial driver, enabled with CONFIG_PARPORT_SERIAL.
142
143config SERIAL_8250_EXAR
144 tristate "8250/16550 Exar/Commtech PCI/PCIe device support"
145 depends on SERIAL_8250_PCI
146 default SERIAL_8250
147 help
148 This builds support for XR17C1xx, XR17V3xx and some Commtech
149 422x PCIe serial cards that are not covered by the more generic
150 SERIAL_8250_PCI option.
151
152config SERIAL_8250_HP300
153 tristate
154 depends on SERIAL_8250 && HP300
155 default SERIAL_8250
156
157config SERIAL_8250_CS
158 tristate "8250/16550 PCMCIA device support"
159 depends on PCMCIA && SERIAL_8250
160 help
161 Say Y here to enable support for 16-bit PCMCIA serial devices,
162 including serial port cards, modems, and the modem functions of
163 multi-function Ethernet/modem cards. (PCMCIA- or PC-cards are
164 credit-card size devices often used with laptops.)
165
166 To compile this driver as a module, choose M here: the
167 module will be called serial_cs.
168
169 If unsure, say N.
170
171config SERIAL_8250_MEN_MCB
172 tristate "MEN MCB UART device support"
173 depends on MCB && SERIAL_8250
174 help
175 This enables support for FPGA based UARTs found on many MEN
176 boards. This driver enables support for the 16z025, 16z057
177 and 16z125 UARTs.
178
179 To compile this driver as a module, chose M here: the
180 module will be called 8250_men_mcb.
181
182
183config SERIAL_8250_NR_UARTS
184 int "Maximum number of 8250/16550 serial ports"
185 depends on SERIAL_8250
186 default "4"
187 help
188 Set this to the number of serial ports you want the driver
189 to support. This includes any ports discovered via ACPI or
190 PCI enumeration and any ports that may be added at run-time
191 via hot-plug, or any ISA multi-port serial cards.
192
193config SERIAL_8250_RUNTIME_UARTS
194 int "Number of 8250/16550 serial ports to register at runtime"
195 depends on SERIAL_8250
196 range 0 SERIAL_8250_NR_UARTS
197 default "4"
198 help
199 Set this to the maximum number of serial ports you want
200 the kernel to register at boot time. This can be overridden
201 with the module parameter "nr_uarts", or boot-time parameter
202 8250.nr_uarts
203
204config SERIAL_8250_EXTENDED
205 bool "Extended 8250/16550 serial driver options"
206 depends on SERIAL_8250
207 help
208 If you wish to use any non-standard features of the standard "dumb"
209 driver, say Y here. This includes HUB6 support, shared serial
210 interrupts, special multiport support, support for more than the
211 four COM 1/2/3/4 boards, etc.
212
213 Note that the answer to this question won't directly affect the
214 kernel: saying N will just cause the configurator to skip all
215 the questions about serial driver options. If unsure, say N.
216
217config SERIAL_8250_MANY_PORTS
218 bool "Support more than 4 legacy serial ports"
219 depends on SERIAL_8250_EXTENDED && !IA64
220 help
221 Say Y here if you have dumb serial boards other than the four
222 standard COM 1/2/3/4 ports. This may happen if you have an AST
223 FourPort, Accent Async, Boca (read the Boca mini-HOWTO, available
224 from <https://www.tldp.org/docs.html#howto>), or other custom
225 serial port hardware which acts similar to standard serial port
226 hardware. If you only use the standard COM 1/2/3/4 ports, you can
227 say N here to save some memory. You can also say Y if you have an
228 "intelligent" multiport card such as Digiboards, etc.
229
230#
231# Multi-port serial cards
232#
233
234config SERIAL_8250_FOURPORT
235 tristate "Support Fourport cards"
236 depends on SERIAL_8250 != n && ISA && SERIAL_8250_MANY_PORTS
237 help
238 Say Y here if you have an AST FourPort serial board.
239
240 To compile this driver as a module, choose M here: the module
241 will be called 8250_fourport.
242
243config SERIAL_8250_ACCENT
244 tristate "Support Accent cards"
245 depends on SERIAL_8250 != n && ISA && SERIAL_8250_MANY_PORTS
246 help
247 Say Y here if you have an Accent Async serial board.
248
249 To compile this driver as a module, choose M here: the module
250 will be called 8250_accent.
251
252config SERIAL_8250_ASPEED_VUART
253 tristate "Aspeed Virtual UART"
254 depends on SERIAL_8250
255 depends on OF
256 depends on REGMAP && MFD_SYSCON
257 help
258 If you want to use the virtual UART (VUART) device on Aspeed
259 BMC platforms, enable this option. This enables the 16550A-
260 compatible device on the local LPC bus, giving a UART device
261 with no physical RS232 connections.
262
263config SERIAL_8250_BOCA
264 tristate "Support Boca cards"
265 depends on SERIAL_8250 != n && ISA && SERIAL_8250_MANY_PORTS
266 help
267 Say Y here if you have a Boca serial board. Please read the Boca
268 mini-HOWTO, available from <https://www.tldp.org/docs.html#howto>
269
270 To compile this driver as a module, choose M here: the module
271 will be called 8250_boca.
272
273config SERIAL_8250_EXAR_ST16C554
274 tristate "Support Exar ST16C554/554D Quad UART"
275 depends on SERIAL_8250 != n && ISA && SERIAL_8250_MANY_PORTS
276 help
277 The Uplogix Envoy TU301 uses this Exar Quad UART. If you are
278 tinkering with your Envoy TU301, or have a machine with this UART,
279 say Y here.
280
281 To compile this driver as a module, choose M here: the module
282 will be called 8250_exar_st16c554.
283
284config SERIAL_8250_HUB6
285 tristate "Support Hub6 cards"
286 depends on SERIAL_8250 != n && ISA && SERIAL_8250_MANY_PORTS
287 help
288 Say Y here if you have a HUB6 serial board.
289
290 To compile this driver as a module, choose M here: the module
291 will be called 8250_hub6.
292
293#
294# Misc. options/drivers.
295#
296
297config SERIAL_8250_SHARE_IRQ
298 bool "Support for sharing serial interrupts"
299 depends on SERIAL_8250_EXTENDED
300 help
301 Some serial boards have hardware support which allows multiple dumb
302 serial ports on the same board to share a single IRQ. To enable
303 support for this in the serial driver, say Y here.
304
305config SERIAL_8250_DETECT_IRQ
306 bool "Autodetect IRQ on standard ports (unsafe)"
307 depends on SERIAL_8250_EXTENDED
308 help
309 Say Y here if you want the kernel to try to guess which IRQ
310 to use for your serial port.
311
312 This is considered unsafe; it is far better to configure the IRQ in
313 a boot script using the setserial command.
314
315 If unsure, say N.
316
317config SERIAL_8250_RSA
318 bool "Support RSA serial ports"
319 depends on SERIAL_8250_EXTENDED
320 help
321 Say Y here if you have a IODATA RSA-DV II/S ISA card and
322 would like to use its >115kbps speeds.
323 You will need to provide module parameter "probe_rsa", or boot-time
324 parameter 8250.probe_rsa with I/O addresses of this card then.
325
326 If you don't have such card, or if unsure, say N.
327
328config SERIAL_8250_DWLIB
329 bool
330
331config SERIAL_8250_ACORN
332 tristate "Acorn expansion card serial port support"
333 depends on ARCH_ACORN && SERIAL_8250
334 help
335 If you have an Atomwide Serial card or Serial Port card for an Acorn
336 system, say Y to this option. The driver can handle 1, 2, or 3 port
337 cards. If unsure, say N.
338
339config SERIAL_8250_BCM2835AUX
340 tristate "BCM2835 auxiliar mini UART support"
341 depends on ARCH_BCM2835 || COMPILE_TEST
342 depends on SERIAL_8250 && SERIAL_8250_SHARE_IRQ
343 help
344 Support for the BCM2835 auxiliar mini UART.
345
346 Features and limitations of the UART are
347 Registers are similar to 16650 registers,
348 set bits in the control registers that are unsupported
349 are ignored and read back as 0
350 7/8 bit operation with 1 start and 1 stop bit
351 8 symbols deep fifo for rx and tx
352 SW controlled RTS and SW readable CTS
353 Clock rate derived from system clock
354 Uses 8 times oversampling (compared to 16 times for 16650)
355 Missing break detection (but break generation)
356 Missing framing error detection
357 Missing parity bit
358 Missing receive time-out interrupt
359 Missing DCD, DSR, DTR and RI signals
360
361 If unsure, say N.
362
363config SERIAL_8250_FSL
364 bool "Freescale 16550 UART support" if COMPILE_TEST && !(PPC || ARM || ARM64)
365 depends on SERIAL_8250_CONSOLE
366 default PPC || ARM || ARM64
367 help
368 Selecting this option enables a workaround for a break-detection
369 erratum for Freescale 16550 UARTs in the 8250 driver. It also
370 enables support for ACPI enumeration.
371
372config SERIAL_8250_DW
373 tristate "Support for Synopsys DesignWare 8250 quirks"
374 depends on SERIAL_8250
375 select SERIAL_8250_DWLIB
376 help
377 Selecting this option will enable handling of the extra features
378 present in the Synopsys DesignWare APB UART.
379
380config SERIAL_8250_EM
381 tristate "Support for Emma Mobile integrated serial port"
382 depends on SERIAL_8250 && HAVE_CLK
383 depends on (ARM && ARCH_RENESAS) || COMPILE_TEST
384 help
385 Selecting this option will add support for the integrated serial
386 port hardware found on the Emma Mobile line of processors.
387 If unsure, say N.
388
389config SERIAL_8250_IOC3
390 tristate "SGI IOC3 8250 UART support"
391 depends on SERIAL_8250
392 depends on SGI_MFD_IOC3 || COMPILE_TEST
393 select SERIAL_8250_EXTENDED
394 select SERIAL_8250_SHARE_IRQ
395 help
396 Enable this if you have a SGI Origin or Octane machine. This module
397 provides basic serial support by directly driving the UART chip
398 behind the IOC3 device on those systems. Maximum baud speed is
399 38400bps using this driver.
400
401config SERIAL_8250_RT288X
402 bool "Ralink RT288x/RT305x/RT3662/RT3883 serial port support"
403 depends on SERIAL_8250
404 default y if MIPS_ALCHEMY || SOC_RT288X || SOC_RT305X || SOC_RT3883 || SOC_MT7620
405 help
406 Selecting this option will add support for the alternate register
407 layout used by Ralink RT288x/RT305x, Alchemy Au1xxx, and some others.
408 If unsure, say N.
409
410config SERIAL_8250_OMAP
411 tristate "Support for OMAP internal UART (8250 based driver)"
412 depends on SERIAL_8250
413 depends on ARCH_OMAP2PLUS || ARCH_K3 || COMPILE_TEST
414 help
415 If you have a machine based on an Texas Instruments OMAP CPU you
416 can enable its onboard serial ports by enabling this option.
417
418 This driver uses ttyS instead of ttyO.
419
420config SERIAL_8250_OMAP_TTYO_FIXUP
421 bool "Replace ttyO with ttyS"
422 depends on SERIAL_8250_OMAP=y && SERIAL_8250_CONSOLE
423 default y
424 help
425 This option replaces the "console=ttyO" argument with the matching
426 ttyS argument if the user did not specified it on the command line.
427 This ensures that the user can see the kernel output during boot
428 which he wouldn't see otherwise. The getty has still to be configured
429 for ttyS instead of ttyO regardless of this option.
430 This option is intended for people who "automatically" enable this
431 driver without knowing that this driver requires a different console=
432 argument. If you read this, please keep this option disabled and
433 instead update your kernel command line. If you prepare a kernel for a
434 distribution or other kind of larger user base then you probably want
435 to keep this option enabled. Otherwise people might complain about a
436 not booting kernel because the serial console remains silent in case
437 they forgot to update the command line.
438
439config SERIAL_8250_LPC18XX
440 tristate "NXP LPC18xx/43xx serial port support"
441 depends on SERIAL_8250 && OF && (ARCH_LPC18XX || COMPILE_TEST)
442 default ARCH_LPC18XX
443 help
444 If you have a LPC18xx/43xx based board and want to use the
445 serial port, say Y to this option. If unsure, say Y.
446
447config SERIAL_8250_MT6577
448 tristate "Mediatek serial port support"
449 depends on SERIAL_8250
450 depends on ARCH_MEDIATEK || COMPILE_TEST
451 help
452 If you have a Mediatek based board and want to use the
453 serial port, say Y to this option. If unsure, say N.
454
455config SERIAL_8250_UNIPHIER
456 tristate "Support for UniPhier on-chip UART"
457 depends on SERIAL_8250
458 depends on ARCH_UNIPHIER || COMPILE_TEST
459 help
460 If you have a UniPhier based board and want to use the on-chip
461 serial ports, say Y to this option. If unsure, say N.
462
463config SERIAL_8250_INGENIC
464 tristate "Support for Ingenic SoC serial ports"
465 depends on SERIAL_8250
466 depends on OF_FLATTREE
467 depends on MIPS || COMPILE_TEST
468 help
469 If you have a system using an Ingenic SoC and wish to make use of
470 its UARTs, say Y to this option. If unsure, say N.
471
472config SERIAL_8250_LPSS
473 tristate "Support for serial ports on Intel LPSS platforms"
474 default SERIAL_8250
475 depends on SERIAL_8250 && PCI
476 depends on X86 || COMPILE_TEST
477 select SERIAL_8250_DWLIB
478 select DW_DMAC_CORE if SERIAL_8250_DMA
479 select DW_DMAC_PCI if (SERIAL_8250_DMA && X86_INTEL_LPSS)
480 select RATIONAL
481 help
482 Selecting this option will enable handling of the extra features
483 present on the UART found on various Intel platforms such as:
484 - Intel Baytrail SoC
485 - Intel Braswell SoC
486 - Intel Quark X1000 SoC
487
488config SERIAL_8250_MID
489 tristate "Support for serial ports on Intel MID platforms"
490 default SERIAL_8250
491 depends on SERIAL_8250 && PCI
492 depends on X86 || COMPILE_TEST
493 select HSU_DMA if SERIAL_8250_DMA
494 select HSU_DMA_PCI if (HSU_DMA && X86_INTEL_MID)
495 select RATIONAL
496 help
497 Selecting this option will enable handling of the extra features
498 present on the UART found on Intel Medfield SOC and various other
499 Intel platforms.
500
501config SERIAL_8250_PERICOM
502 tristate "Support for Pericom and Acces I/O serial ports"
503 default SERIAL_8250
504 depends on SERIAL_8250 && PCI
505 help
506 Selecting this option will enable handling of the extra features
507 present on the Pericom and Acces I/O UARTs.
508
509config SERIAL_8250_PXA
510 tristate "PXA serial port support"
511 depends on SERIAL_8250
512 depends on ARCH_PXA || ARCH_MMP || COMPILE_TEST
513 help
514 If you have a machine based on an Intel XScale PXA2xx CPU you can
515 enable its onboard serial ports by enabling this option. The option is
516 applicable to both devicetree and legacy boards, and early console is
517 part of its support.
518
519config SERIAL_8250_TEGRA
520 tristate "8250 support for Tegra serial ports"
521 default SERIAL_8250
522 depends on SERIAL_8250
523 depends on ARCH_TEGRA || COMPILE_TEST
524 help
525 Select this option if you have machine with an NVIDIA Tegra SoC and
526 wish to enable 8250 serial driver for the Tegra serial interfaces.
527
528config SERIAL_8250_BCM7271
529 tristate "Broadcom 8250 based serial port"
530 depends on SERIAL_8250 && (ARCH_BRCMSTB || COMPILE_TEST)
531 default ARCH_BRCMSTB
532 help
533 If you have a Broadcom STB based board and want to use the
534 enhanced features of the Broadcom 8250 based serial port,
535 including DMA support and high accuracy BAUD rates, say
536 Y to this option. If unsure, say N.
537
538config SERIAL_OF_PLATFORM
539 tristate "Devicetree based probing for 8250 ports"
540 depends on SERIAL_8250 && OF
541 help
542 This option is used for all 8250 compatible serial ports that
543 are probed through devicetree, including Open Firmware based
544 PowerPC systems and embedded systems on architectures using the
545 flattened device tree format.