xref: /openbmc/linux/drivers/char/Kconfig (revision 95298d63)
1# SPDX-License-Identifier: GPL-2.0
2#
3# Character device configuration
4#
5
6menu "Character devices"
7
8source "drivers/tty/Kconfig"
9
10config TTY_PRINTK
11	tristate "TTY driver to output user messages via printk"
12	depends on EXPERT && TTY
13	default n
14	help
15	  If you say Y here, the support for writing user messages (i.e.
16	  console messages) via printk is available.
17
18	  The feature is useful to inline user messages with kernel
19	  messages.
20	  In order to use this feature, you should output user messages
21	  to /dev/ttyprintk or redirect console to this TTY.
22
23	  If unsure, say N.
24
25config TTY_PRINTK_LEVEL
26	depends on TTY_PRINTK
27	int "ttyprintk log level (1-7)"
28	range 1 7
29	default "6"
30	help
31	  Printk log level to use for ttyprintk messages.
32
33config PRINTER
34	tristate "Parallel printer support"
35	depends on PARPORT
36	help
37	  If you intend to attach a printer to the parallel port of your Linux
38	  box (as opposed to using a serial printer; if the connector at the
39	  printer has 9 or 25 holes ["female"], then it's serial), say Y.
40	  Also read the Printing-HOWTO, available from
41	  <http://www.tldp.org/docs.html#howto>.
42
43	  It is possible to share one parallel port among several devices
44	  (e.g. printer and ZIP drive) and it is safe to compile the
45	  corresponding drivers into the kernel.
46
47	  To compile this driver as a module, choose M here and read
48	  <file:Documentation/admin-guide/parport.rst>.  The module will be called lp.
49
50	  If you have several parallel ports, you can specify which ports to
51	  use with the "lp" kernel command line option.  (Try "man bootparam"
52	  or see the documentation of your boot loader (lilo or loadlin) about
53	  how to pass options to the kernel at boot time.)  The syntax of the
54	  "lp" command line option can be found in <file:drivers/char/lp.c>.
55
56	  If you have more than 8 printers, you need to increase the LP_NO
57	  macro in lp.c and the PARPORT_MAX macro in parport.h.
58
59config LP_CONSOLE
60	bool "Support for console on line printer"
61	depends on PRINTER
62	help
63	  If you want kernel messages to be printed out as they occur, you
64	  can have a console on the printer. This option adds support for
65	  doing that; to actually get it to happen you need to pass the
66	  option "console=lp0" to the kernel at boot time.
67
68	  If the printer is out of paper (or off, or unplugged, or too
69	  busy..) the kernel will stall until the printer is ready again.
70	  By defining CONSOLE_LP_STRICT to 0 (at your own risk) you
71	  can make the kernel continue when this happens,
72	  but it'll lose the kernel messages.
73
74	  If unsure, say N.
75
76config PPDEV
77	tristate "Support for user-space parallel port device drivers"
78	depends on PARPORT
79	help
80	  Saying Y to this adds support for /dev/parport device nodes.  This
81	  is needed for programs that want portable access to the parallel
82	  port, for instance deviceid (which displays Plug-and-Play device
83	  IDs).
84
85	  This is the parallel port equivalent of SCSI generic support (sg).
86	  It is safe to say N to this -- it is not needed for normal printing
87	  or parallel port CD-ROM/disk support.
88
89	  To compile this driver as a module, choose M here: the
90	  module will be called ppdev.
91
92	  If unsure, say N.
93
94config VIRTIO_CONSOLE
95	tristate "Virtio console"
96	depends on VIRTIO && TTY
97	select HVC_DRIVER
98	help
99	  Virtio console for use with hypervisors.
100
101	  Also serves as a general-purpose serial device for data
102	  transfer between the guest and host.  Character devices at
103	  /dev/vportNpn will be created when corresponding ports are
104	  found, where N is the device number and n is the port number
105	  within that device.  If specified by the host, a sysfs
106	  attribute called 'name' will be populated with a name for
107	  the port which can be used by udev scripts to create a
108	  symlink to the device.
109
110config IBM_BSR
111	tristate "IBM POWER Barrier Synchronization Register support"
112	depends on PPC_PSERIES
113	help
114	  This devices exposes a hardware mechanism for fast synchronization
115	  of threads across a large system which avoids bouncing a cacheline
116	  between several cores on a system
117
118config POWERNV_OP_PANEL
119	tristate "IBM POWERNV Operator Panel Display support"
120	depends on PPC_POWERNV
121	default m
122	help
123	  If you say Y here, a special character device node, /dev/op_panel,
124	  will be created which exposes the operator panel display on IBM
125	  Power Systems machines with FSPs.
126
127	  If you don't require access to the operator panel display from user
128	  space, say N.
129
130	  If unsure, say M here to build it as a module called powernv-op-panel.
131
132source "drivers/char/ipmi/Kconfig"
133
134config DS1620
135	tristate "NetWinder thermometer support"
136	depends on ARCH_NETWINDER
137	help
138	  Say Y here to include support for the thermal management hardware
139	  found in the NetWinder. This driver allows the user to control the
140	  temperature set points and to read the current temperature.
141
142	  It is also possible to say M here to build it as a module (ds1620)
143	  It is recommended to be used on a NetWinder, but it is not a
144	  necessity.
145
146config NWBUTTON
147	tristate "NetWinder Button"
148	depends on ARCH_NETWINDER
149	help
150	  If you say Y here and create a character device node /dev/nwbutton
151	  with major and minor numbers 10 and 158 ("man mknod"), then every
152	  time the orange button is pressed a number of times, the number of
153	  times the button was pressed will be written to that device.
154
155	  This is most useful for applications, as yet unwritten, which
156	  perform actions based on how many times the button is pressed in a
157	  row.
158
159	  Do not hold the button down for too long, as the driver does not
160	  alter the behaviour of the hardware reset circuitry attached to the
161	  button; it will still execute a hard reset if the button is held
162	  down for longer than approximately five seconds.
163
164	  To compile this driver as a module, choose M here: the
165	  module will be called nwbutton.
166
167	  Most people will answer Y to this question and "Reboot Using Button"
168	  below to be able to initiate a system shutdown from the button.
169
170config NWBUTTON_REBOOT
171	bool "Reboot Using Button"
172	depends on NWBUTTON
173	help
174	  If you say Y here, then you will be able to initiate a system
175	  shutdown and reboot by pressing the orange button a number of times.
176	  The number of presses to initiate the shutdown is two by default,
177	  but this can be altered by modifying the value of NUM_PRESSES_REBOOT
178	  in nwbutton.h and recompiling the driver or, if you compile the
179	  driver as a module, you can specify the number of presses at load
180	  time with "insmod button reboot_count=<something>".
181
182config NWFLASH
183	tristate "NetWinder flash support"
184	depends on ARCH_NETWINDER
185	help
186	  If you say Y here and create a character device /dev/flash with
187	  major 10 and minor 160 you can manipulate the flash ROM containing
188	  the NetWinder firmware. Be careful as accidentally overwriting the
189	  flash contents can render your computer unbootable. On no account
190	  allow random users access to this device. :-)
191
192	  To compile this driver as a module, choose M here: the
193	  module will be called nwflash.
194
195	  If you're not sure, say N.
196
197source "drivers/char/hw_random/Kconfig"
198
199config DTLK
200	tristate "Double Talk PC internal speech card support"
201	depends on ISA
202	help
203	  This driver is for the DoubleTalk PC, a speech synthesizer
204	  manufactured by RC Systems (<http://www.rcsys.com/>).  It is also
205	  called the `internal DoubleTalk'.
206
207	  To compile this driver as a module, choose M here: the
208	  module will be called dtlk.
209
210config XILINX_HWICAP
211	tristate "Xilinx HWICAP Support"
212	depends on MICROBLAZE
213	help
214	  This option enables support for Xilinx Internal Configuration
215	  Access Port (ICAP) driver.  The ICAP is used on Xilinx Virtex
216	  FPGA platforms to partially reconfigure the FPGA at runtime.
217
218	  If unsure, say N.
219
220config R3964
221	tristate "Siemens R3964 line discipline"
222	depends on TTY && BROKEN
223	help
224	  This driver allows synchronous communication with devices using the
225	  Siemens R3964 packet protocol. Unless you are dealing with special
226	  hardware like PLCs, you are unlikely to need this.
227
228	  To compile this driver as a module, choose M here: the
229	  module will be called n_r3964.
230
231	  If unsure, say N.
232
233config APPLICOM
234	tristate "Applicom intelligent fieldbus card support"
235	depends on PCI
236	help
237	  This driver provides the kernel-side support for the intelligent
238	  fieldbus cards made by Applicom International. More information
239	  about these cards can be found on the WWW at the address
240	  <http://www.applicom-int.com/>, or by email from David Woodhouse
241	  <dwmw2@infradead.org>.
242
243	  To compile this driver as a module, choose M here: the
244	  module will be called applicom.
245
246	  If unsure, say N.
247
248config SONYPI
249	tristate "Sony Vaio Programmable I/O Control Device support"
250	depends on X86_32 && PCI && INPUT
251	help
252	  This driver enables access to the Sony Programmable I/O Control
253	  Device which can be found in many (all ?) Sony Vaio laptops.
254
255	  If you have one of those laptops, read
256	  <file:Documentation/admin-guide/laptops/sonypi.rst>, and say Y or M here.
257
258	  To compile this driver as a module, choose M here: the
259	  module will be called sonypi.
260
261config GPIO_TB0219
262	tristate "TANBAC TB0219 GPIO support"
263	depends on TANBAC_TB022X
264	select GPIO_VR41XX
265
266source "drivers/char/pcmcia/Kconfig"
267
268config MWAVE
269	tristate "ACP Modem (Mwave) support"
270	depends on X86 && TTY
271	select SERIAL_8250
272	help
273	  The ACP modem (Mwave) for Linux is a WinModem. It is composed of a
274	  kernel driver and a user level application. Together these components
275	  support direct attachment to public switched telephone networks (PSTNs)
276	  and support selected world wide countries.
277
278	  This version of the ACP Modem driver supports the IBM Thinkpad 600E,
279	  600, and 770 that include on board ACP modem hardware.
280
281	  The modem also supports the standard communications port interface
282	  (ttySx) and is compatible with the Hayes AT Command Set.
283
284	  The user level application needed to use this driver can be found at
285	  the IBM Linux Technology Center (LTC) web site:
286	  <http://www.ibm.com/linux/ltc/>.
287
288	  If you own one of the above IBM Thinkpads which has the Mwave chipset
289	  in it, say Y.
290
291	  To compile this driver as a module, choose M here: the
292	  module will be called mwave.
293
294config SCx200_GPIO
295	tristate "NatSemi SCx200 GPIO Support"
296	depends on SCx200
297	select NSC_GPIO
298	help
299	  Give userspace access to the GPIO pins on the National
300	  Semiconductor SCx200 processors.
301
302	  If compiled as a module, it will be called scx200_gpio.
303
304config PC8736x_GPIO
305	tristate "NatSemi PC8736x GPIO Support"
306	depends on X86_32 && !UML
307	default SCx200_GPIO	# mostly N
308	select NSC_GPIO		# needed for support routines
309	help
310	  Give userspace access to the GPIO pins on the National
311	  Semiconductor PC-8736x (x=[03456]) SuperIO chip.  The chip
312	  has multiple functional units, inc several managed by
313	  hwmon/pc87360 driver.  Tested with PC-87366
314
315	  If compiled as a module, it will be called pc8736x_gpio.
316
317config NSC_GPIO
318	tristate "NatSemi Base GPIO Support"
319	depends on X86_32
320	# selected by SCx200_GPIO and PC8736x_GPIO
321	# what about 2 selectors differing: m != y
322	help
323	  Common support used (and needed) by scx200_gpio and
324	  pc8736x_gpio drivers.  If those drivers are built as
325	  modules, this one will be too, named nsc_gpio
326
327config DEVMEM
328	bool "/dev/mem virtual device support"
329	default y
330	help
331	  Say Y here if you want to support the /dev/mem device.
332	  The /dev/mem device is used to access areas of physical
333	  memory.
334	  When in doubt, say "Y".
335
336config DEVKMEM
337	bool "/dev/kmem virtual device support"
338	# On arm64, VMALLOC_START < PAGE_OFFSET, which confuses kmem read/write
339	depends on !ARM64
340	help
341	  Say Y here if you want to support the /dev/kmem device. The
342	  /dev/kmem device is rarely used, but can be used for certain
343	  kind of kernel debugging operations.
344	  When in doubt, say "N".
345
346config NVRAM
347	tristate "/dev/nvram support"
348	depends on X86 || HAVE_ARCH_NVRAM_OPS
349	default M68K || PPC
350	help
351	  If you say Y here and create a character special file /dev/nvram
352	  with major number 10 and minor number 144 using mknod ("man mknod"),
353	  you get read and write access to the non-volatile memory.
354
355	  /dev/nvram may be used to view settings in NVRAM or to change them
356	  (with some utility). It could also be used to frequently
357	  save a few bits of very important data that may not be lost over
358	  power-off and for which writing to disk is too insecure. Note
359	  however that most NVRAM space in a PC belongs to the BIOS and you
360	  should NEVER idly tamper with it. See Ralf Brown's interrupt list
361	  for a guide to the use of CMOS bytes by your BIOS.
362
363	  This memory is conventionally called "NVRAM" on PowerPC machines,
364	  "CMOS RAM" on PCs, "NVRAM" on Ataris and "PRAM" on Macintoshes.
365
366	  To compile this driver as a module, choose M here: the
367	  module will be called nvram.
368
369config RAW_DRIVER
370	tristate "RAW driver (/dev/raw/rawN)"
371	depends on BLOCK
372	help
373	  The raw driver permits block devices to be bound to /dev/raw/rawN.
374	  Once bound, I/O against /dev/raw/rawN uses efficient zero-copy I/O.
375	  See the raw(8) manpage for more details.
376
377	  Applications should preferably open the device (eg /dev/hda1)
378	  with the O_DIRECT flag.
379
380config MAX_RAW_DEVS
381	int "Maximum number of RAW devices to support (1-65536)"
382	depends on RAW_DRIVER
383	range 1 65536
384	default "256"
385	help
386	  The maximum number of RAW devices that are supported.
387	  Default is 256. Increase this number in case you need lots of
388	  raw devices.
389
390config DEVPORT
391	bool "/dev/port character device"
392	depends on ISA || PCI
393	default y
394	help
395	  Say Y here if you want to support the /dev/port device. The /dev/port
396	  device is similar to /dev/mem, but for I/O ports.
397
398config HPET
399	bool "HPET - High Precision Event Timer" if (X86 || IA64)
400	default n
401	depends on ACPI
402	help
403	  If you say Y here, you will have a miscdevice named "/dev/hpet/".  Each
404	  open selects one of the timers supported by the HPET.  The timers are
405	  non-periodic and/or periodic.
406
407config HPET_MMAP
408	bool "Allow mmap of HPET"
409	default y
410	depends on HPET
411	help
412	  If you say Y here, user applications will be able to mmap
413	  the HPET registers.
414
415config HPET_MMAP_DEFAULT
416	bool "Enable HPET MMAP access by default"
417	default y
418	depends on HPET_MMAP
419	help
420	  In some hardware implementations, the page containing HPET
421	  registers may also contain other things that shouldn't be
422	  exposed to the user.  This option selects the default (if
423	  kernel parameter hpet_mmap is not set) user access to the
424	  registers for applications that require it.
425
426config HANGCHECK_TIMER
427	tristate "Hangcheck timer"
428	depends on X86 || IA64 || PPC64 || S390
429	help
430	  The hangcheck-timer module detects when the system has gone
431	  out to lunch past a certain margin.  It can reboot the system
432	  or merely print a warning.
433
434config UV_MMTIMER
435	tristate "UV_MMTIMER Memory mapped RTC for SGI UV"
436	depends on X86_UV
437	default m
438	help
439	  The uv_mmtimer device allows direct userspace access to the
440	  UV system timer.
441
442source "drivers/char/tpm/Kconfig"
443
444config TELCLOCK
445	tristate "Telecom clock driver for ATCA SBC"
446	depends on X86
447	default n
448	help
449	  The telecom clock device is specific to the MPCBL0010 and MPCBL0050
450	  ATCA computers and allows direct userspace access to the
451	  configuration of the telecom clock configuration settings.  This
452	  device is used for hardware synchronization across the ATCA backplane
453	  fabric.  Upon loading, the driver exports a sysfs directory,
454	  /sys/devices/platform/telco_clock, with a number of files for
455	  controlling the behavior of this hardware.
456
457source "drivers/s390/char/Kconfig"
458
459source "drivers/char/xillybus/Kconfig"
460
461config ADI
462	tristate "SPARC Privileged ADI driver"
463	depends on SPARC64
464	default m
465	help
466	  SPARC M7 and newer processors utilize ADI (Application Data
467	  Integrity) to version and protect memory.  This driver provides
468	  read/write access to the ADI versions for privileged processes.
469	  This feature is also known as MCD (Memory Corruption Detection)
470	  and SSM (Silicon Secured Memory).  Intended consumers of this
471	  driver include crash and makedumpfile.
472
473endmenu
474
475config RANDOM_TRUST_CPU
476	bool "Trust the CPU manufacturer to initialize Linux's CRNG"
477	depends on ARCH_RANDOM
478	default n
479	help
480	Assume that CPU manufacturer (e.g., Intel or AMD for RDSEED or
481	RDRAND, IBM for the S390 and Power PC architectures) is trustworthy
482	for the purposes of initializing Linux's CRNG.  Since this is not
483	something that can be independently audited, this amounts to trusting
484	that CPU manufacturer (perhaps with the insistence or mandate
485	of a Nation State's intelligence or law enforcement agencies)
486	has not installed a hidden back door to compromise the CPU's
487	random number generation facilities. This can also be configured
488	at boot with "random.trust_cpu=on/off".
489
490config RANDOM_TRUST_BOOTLOADER
491	bool "Trust the bootloader to initialize Linux's CRNG"
492	help
493	Some bootloaders can provide entropy to increase the kernel's initial
494	device randomness. Say Y here to assume the entropy provided by the
495	booloader is trustworthy so it will be added to the kernel's entropy
496	pool. Otherwise, say N here so it will be regarded as device input that
497	only mixes the entropy pool.
498