xref: /openbmc/linux/drivers/char/Kconfig (revision bbb774d9)
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, or boot
22	  the kernel with console=ttyprintk.
23
24	  If unsure, say N.
25
26config TTY_PRINTK_LEVEL
27	depends on TTY_PRINTK
28	int "ttyprintk log level (1-7)"
29	range 1 7
30	default "6"
31	help
32	  Printk log level to use for ttyprintk messages.
33
34config PRINTER
35	tristate "Parallel printer support"
36	depends on PARPORT
37	help
38	  If you intend to attach a printer to the parallel port of your Linux
39	  box (as opposed to using a serial printer; if the connector at the
40	  printer has 9 or 25 holes ["female"], then it's serial), say Y.
41	  Also read the Printing-HOWTO, available from
42	  <https://www.tldp.org/docs.html#howto>.
43
44	  It is possible to share one parallel port among several devices
45	  (e.g. printer and ZIP drive) and it is safe to compile the
46	  corresponding drivers into the kernel.
47
48	  To compile this driver as a module, choose M here and read
49	  <file:Documentation/admin-guide/parport.rst>.  The module will be called lp.
50
51	  If you have several parallel ports, you can specify which ports to
52	  use with the "lp" kernel command line option.  (Try "man bootparam"
53	  or see the documentation of your boot loader (lilo or loadlin) about
54	  how to pass options to the kernel at boot time.)  The syntax of the
55	  "lp" command line option can be found in <file:drivers/char/lp.c>.
56
57	  If you have more than 8 printers, you need to increase the LP_NO
58	  macro in lp.c and the PARPORT_MAX macro in parport.h.
59
60config LP_CONSOLE
61	bool "Support for console on line printer"
62	depends on PRINTER
63	help
64	  If you want kernel messages to be printed out as they occur, you
65	  can have a console on the printer. This option adds support for
66	  doing that; to actually get it to happen you need to pass the
67	  option "console=lp0" to the kernel at boot time.
68
69	  If the printer is out of paper (or off, or unplugged, or too
70	  busy..) the kernel will stall until the printer is ready again.
71	  By defining CONSOLE_LP_STRICT to 0 (at your own risk) you
72	  can make the kernel continue when this happens,
73	  but it'll lose the kernel messages.
74
75	  If unsure, say N.
76
77config PPDEV
78	tristate "Support for user-space parallel port device drivers"
79	depends on PARPORT
80	help
81	  Saying Y to this adds support for /dev/parport device nodes.  This
82	  is needed for programs that want portable access to the parallel
83	  port, for instance deviceid (which displays Plug-and-Play device
84	  IDs).
85
86	  This is the parallel port equivalent of SCSI generic support (sg).
87	  It is safe to say N to this -- it is not needed for normal printing
88	  or parallel port CD-ROM/disk support.
89
90	  To compile this driver as a module, choose M here: the
91	  module will be called ppdev.
92
93	  If unsure, say N.
94
95config VIRTIO_CONSOLE
96	tristate "Virtio console"
97	depends on TTY
98	select HVC_DRIVER
99	select VIRTIO
100	help
101	  Virtio console for use with hypervisors.
102
103	  Also serves as a general-purpose serial device for data
104	  transfer between the guest and host.  Character devices at
105	  /dev/vportNpn will be created when corresponding ports are
106	  found, where N is the device number and n is the port number
107	  within that device.  If specified by the host, a sysfs
108	  attribute called 'name' will be populated with a name for
109	  the port which can be used by udev scripts to create a
110	  symlink to the device.
111
112config IBM_BSR
113	tristate "IBM POWER Barrier Synchronization Register support"
114	depends on PPC_PSERIES
115	help
116	  This devices exposes a hardware mechanism for fast synchronization
117	  of threads across a large system which avoids bouncing a cacheline
118	  between several cores on a system
119
120config POWERNV_OP_PANEL
121	tristate "IBM POWERNV Operator Panel Display support"
122	depends on PPC_POWERNV
123	default m
124	help
125	  If you say Y here, a special character device node, /dev/op_panel,
126	  will be created which exposes the operator panel display on IBM
127	  Power Systems machines with FSPs.
128
129	  If you don't require access to the operator panel display from user
130	  space, say N.
131
132	  If unsure, say M here to build it as a module called powernv-op-panel.
133
134source "drivers/char/ipmi/Kconfig"
135
136config DS1620
137	tristate "NetWinder thermometer support"
138	depends on ARCH_NETWINDER
139	help
140	  Say Y here to include support for the thermal management hardware
141	  found in the NetWinder. This driver allows the user to control the
142	  temperature set points and to read the current temperature.
143
144	  It is also possible to say M here to build it as a module (ds1620)
145	  It is recommended to be used on a NetWinder, but it is not a
146	  necessity.
147
148config NWBUTTON
149	tristate "NetWinder Button"
150	depends on ARCH_NETWINDER
151	help
152	  If you say Y here and create a character device node /dev/nwbutton
153	  with major and minor numbers 10 and 158 ("man mknod"), then every
154	  time the orange button is pressed a number of times, the number of
155	  times the button was pressed will be written to that device.
156
157	  This is most useful for applications, as yet unwritten, which
158	  perform actions based on how many times the button is pressed in a
159	  row.
160
161	  Do not hold the button down for too long, as the driver does not
162	  alter the behaviour of the hardware reset circuitry attached to the
163	  button; it will still execute a hard reset if the button is held
164	  down for longer than approximately five seconds.
165
166	  To compile this driver as a module, choose M here: the
167	  module will be called nwbutton.
168
169	  Most people will answer Y to this question and "Reboot Using Button"
170	  below to be able to initiate a system shutdown from the button.
171
172config NWBUTTON_REBOOT
173	bool "Reboot Using Button"
174	depends on NWBUTTON
175	help
176	  If you say Y here, then you will be able to initiate a system
177	  shutdown and reboot by pressing the orange button a number of times.
178	  The number of presses to initiate the shutdown is two by default,
179	  but this can be altered by modifying the value of NUM_PRESSES_REBOOT
180	  in nwbutton.h and recompiling the driver or, if you compile the
181	  driver as a module, you can specify the number of presses at load
182	  time with "insmod button reboot_count=<something>".
183
184config NWFLASH
185	tristate "NetWinder flash support"
186	depends on ARCH_NETWINDER
187	help
188	  If you say Y here and create a character device /dev/flash with
189	  major 10 and minor 160 you can manipulate the flash ROM containing
190	  the NetWinder firmware. Be careful as accidentally overwriting the
191	  flash contents can render your computer unbootable. On no account
192	  allow random users access to this device. :-)
193
194	  To compile this driver as a module, choose M here: the
195	  module will be called nwflash.
196
197	  If you're not sure, say N.
198
199source "drivers/char/hw_random/Kconfig"
200
201config DTLK
202	tristate "Double Talk PC internal speech card support"
203	depends on ISA
204	help
205	  This driver is for the DoubleTalk PC, a speech synthesizer
206	  manufactured by RC Systems (<https://www.rcsys.com/>).  It is also
207	  called the `internal DoubleTalk'.
208
209	  To compile this driver as a module, choose M here: the
210	  module will be called dtlk.
211
212config XILINX_HWICAP
213	tristate "Xilinx HWICAP Support"
214	depends on MICROBLAZE
215	help
216	  This option enables support for Xilinx Internal Configuration
217	  Access Port (ICAP) driver.  The ICAP is used on Xilinx Virtex
218	  FPGA platforms to partially reconfigure the FPGA at runtime.
219
220	  If unsure, say N.
221
222config APPLICOM
223	tristate "Applicom intelligent fieldbus card support"
224	depends on PCI
225	help
226	  This driver provides the kernel-side support for the intelligent
227	  fieldbus cards made by Applicom International. More information
228	  about these cards can be found on the WWW at the address
229	  <https://www.applicom-int.com/>, or by email from David Woodhouse
230	  <dwmw2@infradead.org>.
231
232	  To compile this driver as a module, choose M here: the
233	  module will be called applicom.
234
235	  If unsure, say N.
236
237config SONYPI
238	tristate "Sony Vaio Programmable I/O Control Device support"
239	depends on X86_32 && PCI && INPUT
240	help
241	  This driver enables access to the Sony Programmable I/O Control
242	  Device which can be found in many (all ?) Sony Vaio laptops.
243
244	  If you have one of those laptops, read
245	  <file:Documentation/admin-guide/laptops/sonypi.rst>, and say Y or M here.
246
247	  To compile this driver as a module, choose M here: the
248	  module will be called sonypi.
249
250source "drivers/char/pcmcia/Kconfig"
251
252config MWAVE
253	tristate "ACP Modem (Mwave) support"
254	depends on X86 && TTY
255	select SERIAL_8250
256	help
257	  The ACP modem (Mwave) for Linux is a WinModem. It is composed of a
258	  kernel driver and a user level application. Together these components
259	  support direct attachment to public switched telephone networks (PSTNs)
260	  and support selected world wide countries.
261
262	  This version of the ACP Modem driver supports the IBM Thinkpad 600E,
263	  600, and 770 that include on board ACP modem hardware.
264
265	  The modem also supports the standard communications port interface
266	  (ttySx) and is compatible with the Hayes AT Command Set.
267
268	  The user level application needed to use this driver can be found at
269	  the IBM Linux Technology Center (LTC) web site:
270	  <http://www.ibm.com/linux/ltc/>.
271
272	  If you own one of the above IBM Thinkpads which has the Mwave chipset
273	  in it, say Y.
274
275	  To compile this driver as a module, choose M here: the
276	  module will be called mwave.
277
278config SCx200_GPIO
279	tristate "NatSemi SCx200 GPIO Support"
280	depends on SCx200
281	select NSC_GPIO
282	help
283	  Give userspace access to the GPIO pins on the National
284	  Semiconductor SCx200 processors.
285
286	  If compiled as a module, it will be called scx200_gpio.
287
288config PC8736x_GPIO
289	tristate "NatSemi PC8736x GPIO Support"
290	depends on X86_32 && !UML
291	default SCx200_GPIO	# mostly N
292	select NSC_GPIO		# needed for support routines
293	help
294	  Give userspace access to the GPIO pins on the National
295	  Semiconductor PC-8736x (x=[03456]) SuperIO chip.  The chip
296	  has multiple functional units, inc several managed by
297	  hwmon/pc87360 driver.  Tested with PC-87366
298
299	  If compiled as a module, it will be called pc8736x_gpio.
300
301config NSC_GPIO
302	tristate "NatSemi Base GPIO Support"
303	depends on X86_32
304	# selected by SCx200_GPIO and PC8736x_GPIO
305	# what about 2 selectors differing: m != y
306	help
307	  Common support used (and needed) by scx200_gpio and
308	  pc8736x_gpio drivers.  If those drivers are built as
309	  modules, this one will be too, named nsc_gpio
310
311config DEVMEM
312	bool "/dev/mem virtual device support"
313	default y
314	help
315	  Say Y here if you want to support the /dev/mem device.
316	  The /dev/mem device is used to access areas of physical
317	  memory.
318	  When in doubt, say "Y".
319
320config NVRAM
321	tristate "/dev/nvram support"
322	depends on X86 || HAVE_ARCH_NVRAM_OPS
323	default M68K || PPC
324	help
325	  If you say Y here and create a character special file /dev/nvram
326	  with major number 10 and minor number 144 using mknod ("man mknod"),
327	  you get read and write access to the non-volatile memory.
328
329	  /dev/nvram may be used to view settings in NVRAM or to change them
330	  (with some utility). It could also be used to frequently
331	  save a few bits of very important data that may not be lost over
332	  power-off and for which writing to disk is too insecure. Note
333	  however that most NVRAM space in a PC belongs to the BIOS and you
334	  should NEVER idly tamper with it. See Ralf Brown's interrupt list
335	  for a guide to the use of CMOS bytes by your BIOS.
336
337	  This memory is conventionally called "NVRAM" on PowerPC machines,
338	  "CMOS RAM" on PCs, "NVRAM" on Ataris and "PRAM" on Macintoshes.
339
340	  To compile this driver as a module, choose M here: the
341	  module will be called nvram.
342
343config DEVPORT
344	bool "/dev/port character device"
345	depends on ISA || PCI
346	default y
347	help
348	  Say Y here if you want to support the /dev/port device. The /dev/port
349	  device is similar to /dev/mem, but for I/O ports.
350
351config HPET
352	bool "HPET - High Precision Event Timer" if (X86 || IA64)
353	default n
354	depends on ACPI
355	help
356	  If you say Y here, you will have a miscdevice named "/dev/hpet/".  Each
357	  open selects one of the timers supported by the HPET.  The timers are
358	  non-periodic and/or periodic.
359
360config HPET_MMAP
361	bool "Allow mmap of HPET"
362	default y
363	depends on HPET
364	help
365	  If you say Y here, user applications will be able to mmap
366	  the HPET registers.
367
368config HPET_MMAP_DEFAULT
369	bool "Enable HPET MMAP access by default"
370	default y
371	depends on HPET_MMAP
372	help
373	  In some hardware implementations, the page containing HPET
374	  registers may also contain other things that shouldn't be
375	  exposed to the user.  This option selects the default (if
376	  kernel parameter hpet_mmap is not set) user access to the
377	  registers for applications that require it.
378
379config HANGCHECK_TIMER
380	tristate "Hangcheck timer"
381	depends on X86 || IA64 || PPC64 || S390
382	help
383	  The hangcheck-timer module detects when the system has gone
384	  out to lunch past a certain margin.  It can reboot the system
385	  or merely print a warning.
386
387config UV_MMTIMER
388	tristate "UV_MMTIMER Memory mapped RTC for SGI UV"
389	depends on X86_UV
390	default m
391	help
392	  The uv_mmtimer device allows direct userspace access to the
393	  UV system timer.
394
395source "drivers/char/tpm/Kconfig"
396
397config TELCLOCK
398	tristate "Telecom clock driver for ATCA SBC"
399	depends on X86
400	default n
401	help
402	  The telecom clock device is specific to the MPCBL0010 and MPCBL0050
403	  ATCA computers and allows direct userspace access to the
404	  configuration of the telecom clock configuration settings.  This
405	  device is used for hardware synchronization across the ATCA backplane
406	  fabric.  Upon loading, the driver exports a sysfs directory,
407	  /sys/devices/platform/telco_clock, with a number of files for
408	  controlling the behavior of this hardware.
409
410source "drivers/s390/char/Kconfig"
411
412source "drivers/char/xillybus/Kconfig"
413
414config ADI
415	tristate "SPARC Privileged ADI driver"
416	depends on SPARC64
417	default m
418	help
419	  SPARC M7 and newer processors utilize ADI (Application Data
420	  Integrity) to version and protect memory.  This driver provides
421	  read/write access to the ADI versions for privileged processes.
422	  This feature is also known as MCD (Memory Corruption Detection)
423	  and SSM (Silicon Secured Memory).  Intended consumers of this
424	  driver include crash and makedumpfile.
425
426config RANDOM_TRUST_CPU
427	bool "Initialize RNG using CPU RNG instructions"
428	default y
429	help
430	  Initialize the RNG using random numbers supplied by the CPU's
431	  RNG instructions (e.g. RDRAND), if supported and available. These
432	  random numbers are never used directly, but are rather hashed into
433	  the main input pool, and this happens regardless of whether or not
434	  this option is enabled. Instead, this option controls whether the
435	  they are credited and hence can initialize the RNG. Additionally,
436	  other sources of randomness are always used, regardless of this
437	  setting.  Enabling this implies trusting that the CPU can supply high
438	  quality and non-backdoored random numbers.
439
440	  Say Y here unless you have reason to mistrust your CPU or believe
441	  its RNG facilities may be faulty. This may also be configured at
442	  boot time with "random.trust_cpu=on/off".
443
444config RANDOM_TRUST_BOOTLOADER
445	bool "Initialize RNG using bootloader-supplied seed"
446	default y
447	help
448	  Initialize the RNG using a seed supplied by the bootloader or boot
449	  environment (e.g. EFI or a bootloader-generated device tree). This
450	  seed is not used directly, but is rather hashed into the main input
451	  pool, and this happens regardless of whether or not this option is
452	  enabled. Instead, this option controls whether the seed is credited
453	  and hence can initialize the RNG. Additionally, other sources of
454	  randomness are always used, regardless of this setting. Enabling
455	  this implies trusting that the bootloader can supply high quality and
456	  non-backdoored seeds.
457
458	  Say Y here unless you have reason to mistrust your bootloader or
459	  believe its RNG facilities may be faulty. This may also be configured
460	  at boot time with "random.trust_bootloader=on/off".
461
462endmenu
463