1# SPDX-License-Identifier: GPL-2.0 2# 3# Character device configuration 4# 5 6menu "Character devices" 7 8source "drivers/tty/Kconfig" 9 10config DEVMEM 11 bool "/dev/mem virtual device support" 12 default y 13 help 14 Say Y here if you want to support the /dev/mem device. 15 The /dev/mem device is used to access areas of physical 16 memory. 17 When in doubt, say "Y". 18 19config DEVKMEM 20 bool "/dev/kmem virtual device support" 21 # On arm64, VMALLOC_START < PAGE_OFFSET, which confuses kmem read/write 22 depends on !ARM64 23 help 24 Say Y here if you want to support the /dev/kmem device. The 25 /dev/kmem device is rarely used, but can be used for certain 26 kind of kernel debugging operations. 27 When in doubt, say "N". 28 29source "drivers/tty/serial/Kconfig" 30source "drivers/tty/serdev/Kconfig" 31 32config TTY_PRINTK 33 tristate "TTY driver to output user messages via printk" 34 depends on EXPERT && TTY 35 default n 36 ---help--- 37 If you say Y here, the support for writing user messages (i.e. 38 console messages) via printk is available. 39 40 The feature is useful to inline user messages with kernel 41 messages. 42 In order to use this feature, you should output user messages 43 to /dev/ttyprintk or redirect console to this TTY. 44 45 If unsure, say N. 46 47config TTY_PRINTK_LEVEL 48 depends on TTY_PRINTK 49 int "ttyprintk log level (1-7)" 50 range 1 7 51 default "6" 52 help 53 Printk log level to use for ttyprintk messages. 54 55config PRINTER 56 tristate "Parallel printer support" 57 depends on PARPORT 58 ---help--- 59 If you intend to attach a printer to the parallel port of your Linux 60 box (as opposed to using a serial printer; if the connector at the 61 printer has 9 or 25 holes ["female"], then it's serial), say Y. 62 Also read the Printing-HOWTO, available from 63 <http://www.tldp.org/docs.html#howto>. 64 65 It is possible to share one parallel port among several devices 66 (e.g. printer and ZIP drive) and it is safe to compile the 67 corresponding drivers into the kernel. 68 69 To compile this driver as a module, choose M here and read 70 <file:Documentation/admin-guide/parport.rst>. The module will be called lp. 71 72 If you have several parallel ports, you can specify which ports to 73 use with the "lp" kernel command line option. (Try "man bootparam" 74 or see the documentation of your boot loader (lilo or loadlin) about 75 how to pass options to the kernel at boot time.) The syntax of the 76 "lp" command line option can be found in <file:drivers/char/lp.c>. 77 78 If you have more than 8 printers, you need to increase the LP_NO 79 macro in lp.c and the PARPORT_MAX macro in parport.h. 80 81config LP_CONSOLE 82 bool "Support for console on line printer" 83 depends on PRINTER 84 ---help--- 85 If you want kernel messages to be printed out as they occur, you 86 can have a console on the printer. This option adds support for 87 doing that; to actually get it to happen you need to pass the 88 option "console=lp0" to the kernel at boot time. 89 90 If the printer is out of paper (or off, or unplugged, or too 91 busy..) the kernel will stall until the printer is ready again. 92 By defining CONSOLE_LP_STRICT to 0 (at your own risk) you 93 can make the kernel continue when this happens, 94 but it'll lose the kernel messages. 95 96 If unsure, say N. 97 98config PPDEV 99 tristate "Support for user-space parallel port device drivers" 100 depends on PARPORT 101 ---help--- 102 Saying Y to this adds support for /dev/parport device nodes. This 103 is needed for programs that want portable access to the parallel 104 port, for instance deviceid (which displays Plug-and-Play device 105 IDs). 106 107 This is the parallel port equivalent of SCSI generic support (sg). 108 It is safe to say N to this -- it is not needed for normal printing 109 or parallel port CD-ROM/disk support. 110 111 To compile this driver as a module, choose M here: the 112 module will be called ppdev. 113 114 If unsure, say N. 115 116source "drivers/tty/hvc/Kconfig" 117 118config VIRTIO_CONSOLE 119 tristate "Virtio console" 120 depends on VIRTIO && TTY 121 select HVC_DRIVER 122 help 123 Virtio console for use with hypervisors. 124 125 Also serves as a general-purpose serial device for data 126 transfer between the guest and host. Character devices at 127 /dev/vportNpn will be created when corresponding ports are 128 found, where N is the device number and n is the port number 129 within that device. If specified by the host, a sysfs 130 attribute called 'name' will be populated with a name for 131 the port which can be used by udev scripts to create a 132 symlink to the device. 133 134config IBM_BSR 135 tristate "IBM POWER Barrier Synchronization Register support" 136 depends on PPC_PSERIES 137 help 138 This devices exposes a hardware mechanism for fast synchronization 139 of threads across a large system which avoids bouncing a cacheline 140 between several cores on a system 141 142config POWERNV_OP_PANEL 143 tristate "IBM POWERNV Operator Panel Display support" 144 depends on PPC_POWERNV 145 default m 146 help 147 If you say Y here, a special character device node, /dev/op_panel, 148 will be created which exposes the operator panel display on IBM 149 Power Systems machines with FSPs. 150 151 If you don't require access to the operator panel display from user 152 space, say N. 153 154 If unsure, say M here to build it as a module called powernv-op-panel. 155 156source "drivers/char/ipmi/Kconfig" 157 158config DS1620 159 tristate "NetWinder thermometer support" 160 depends on ARCH_NETWINDER 161 help 162 Say Y here to include support for the thermal management hardware 163 found in the NetWinder. This driver allows the user to control the 164 temperature set points and to read the current temperature. 165 166 It is also possible to say M here to build it as a module (ds1620) 167 It is recommended to be used on a NetWinder, but it is not a 168 necessity. 169 170config NWBUTTON 171 tristate "NetWinder Button" 172 depends on ARCH_NETWINDER 173 ---help--- 174 If you say Y here and create a character device node /dev/nwbutton 175 with major and minor numbers 10 and 158 ("man mknod"), then every 176 time the orange button is pressed a number of times, the number of 177 times the button was pressed will be written to that device. 178 179 This is most useful for applications, as yet unwritten, which 180 perform actions based on how many times the button is pressed in a 181 row. 182 183 Do not hold the button down for too long, as the driver does not 184 alter the behaviour of the hardware reset circuitry attached to the 185 button; it will still execute a hard reset if the button is held 186 down for longer than approximately five seconds. 187 188 To compile this driver as a module, choose M here: the 189 module will be called nwbutton. 190 191 Most people will answer Y to this question and "Reboot Using Button" 192 below to be able to initiate a system shutdown from the button. 193 194config NWBUTTON_REBOOT 195 bool "Reboot Using Button" 196 depends on NWBUTTON 197 help 198 If you say Y here, then you will be able to initiate a system 199 shutdown and reboot by pressing the orange button a number of times. 200 The number of presses to initiate the shutdown is two by default, 201 but this can be altered by modifying the value of NUM_PRESSES_REBOOT 202 in nwbutton.h and recompiling the driver or, if you compile the 203 driver as a module, you can specify the number of presses at load 204 time with "insmod button reboot_count=<something>". 205 206config NWFLASH 207 tristate "NetWinder flash support" 208 depends on ARCH_NETWINDER 209 ---help--- 210 If you say Y here and create a character device /dev/flash with 211 major 10 and minor 160 you can manipulate the flash ROM containing 212 the NetWinder firmware. Be careful as accidentally overwriting the 213 flash contents can render your computer unbootable. On no account 214 allow random users access to this device. :-) 215 216 To compile this driver as a module, choose M here: the 217 module will be called nwflash. 218 219 If you're not sure, say N. 220 221source "drivers/char/hw_random/Kconfig" 222 223config NVRAM 224 tristate "/dev/nvram support" 225 depends on X86 || HAVE_ARCH_NVRAM_OPS 226 default M68K || PPC 227 ---help--- 228 If you say Y here and create a character special file /dev/nvram 229 with major number 10 and minor number 144 using mknod ("man mknod"), 230 you get read and write access to the non-volatile memory. 231 232 /dev/nvram may be used to view settings in NVRAM or to change them 233 (with some utility). It could also be used to frequently 234 save a few bits of very important data that may not be lost over 235 power-off and for which writing to disk is too insecure. Note 236 however that most NVRAM space in a PC belongs to the BIOS and you 237 should NEVER idly tamper with it. See Ralf Brown's interrupt list 238 for a guide to the use of CMOS bytes by your BIOS. 239 240 This memory is conventionally called "NVRAM" on PowerPC machines, 241 "CMOS RAM" on PCs, "NVRAM" on Ataris and "PRAM" on Macintoshes. 242 243 To compile this driver as a module, choose M here: the 244 module will be called nvram. 245 246# 247# These legacy RTC drivers just cause too many conflicts with the generic 248# RTC framework ... let's not even try to coexist any more. 249# 250if RTC_LIB=n 251 252config RTC 253 tristate "Enhanced Real Time Clock Support (legacy PC RTC driver)" 254 depends on ALPHA 255 ---help--- 256 If you say Y here and create a character special file /dev/rtc with 257 major number 10 and minor number 135 using mknod ("man mknod"), you 258 will get access to the real time clock (or hardware clock) built 259 into your computer. 260 261 Every PC has such a clock built in. It can be used to generate 262 signals from as low as 1Hz up to 8192Hz, and can also be used 263 as a 24 hour alarm. It reports status information via the file 264 /proc/driver/rtc and its behaviour is set by various ioctls on 265 /dev/rtc. 266 267 If you run Linux on a multiprocessor machine and said Y to 268 "Symmetric Multi Processing" above, you should say Y here to read 269 and set the RTC in an SMP compatible fashion. 270 271 If you think you have a use for such a device (such as periodic data 272 sampling), then say Y here, and read <file:Documentation/admin-guide/rtc.rst> 273 for details. 274 275 To compile this driver as a module, choose M here: the 276 module will be called rtc. 277 278config JS_RTC 279 tristate "Enhanced Real Time Clock Support" 280 depends on SPARC32 && PCI 281 ---help--- 282 If you say Y here and create a character special file /dev/rtc with 283 major number 10 and minor number 135 using mknod ("man mknod"), you 284 will get access to the real time clock (or hardware clock) built 285 into your computer. 286 287 Every PC has such a clock built in. It can be used to generate 288 signals from as low as 1Hz up to 8192Hz, and can also be used 289 as a 24 hour alarm. It reports status information via the file 290 /proc/driver/rtc and its behaviour is set by various ioctls on 291 /dev/rtc. 292 293 If you think you have a use for such a device (such as periodic data 294 sampling), then say Y here, and read <file:Documentation/admin-guide/rtc.rst> 295 for details. 296 297 To compile this driver as a module, choose M here: the 298 module will be called js-rtc. 299 300config EFI_RTC 301 bool "EFI Real Time Clock Services" 302 depends on IA64 303 304endif # RTC_LIB 305 306config DTLK 307 tristate "Double Talk PC internal speech card support" 308 depends on ISA 309 help 310 This driver is for the DoubleTalk PC, a speech synthesizer 311 manufactured by RC Systems (<http://www.rcsys.com/>). It is also 312 called the `internal DoubleTalk'. 313 314 To compile this driver as a module, choose M here: the 315 module will be called dtlk. 316 317config XILINX_HWICAP 318 tristate "Xilinx HWICAP Support" 319 depends on XILINX_VIRTEX || MICROBLAZE 320 help 321 This option enables support for Xilinx Internal Configuration 322 Access Port (ICAP) driver. The ICAP is used on Xilinx Virtex 323 FPGA platforms to partially reconfigure the FPGA at runtime. 324 325 If unsure, say N. 326 327config R3964 328 tristate "Siemens R3964 line discipline" 329 depends on TTY && BROKEN 330 ---help--- 331 This driver allows synchronous communication with devices using the 332 Siemens R3964 packet protocol. Unless you are dealing with special 333 hardware like PLCs, you are unlikely to need this. 334 335 To compile this driver as a module, choose M here: the 336 module will be called n_r3964. 337 338 If unsure, say N. 339 340config APPLICOM 341 tristate "Applicom intelligent fieldbus card support" 342 depends on PCI 343 ---help--- 344 This driver provides the kernel-side support for the intelligent 345 fieldbus cards made by Applicom International. More information 346 about these cards can be found on the WWW at the address 347 <http://www.applicom-int.com/>, or by email from David Woodhouse 348 <dwmw2@infradead.org>. 349 350 To compile this driver as a module, choose M here: the 351 module will be called applicom. 352 353 If unsure, say N. 354 355config SONYPI 356 tristate "Sony Vaio Programmable I/O Control Device support" 357 depends on X86_32 && PCI && INPUT 358 ---help--- 359 This driver enables access to the Sony Programmable I/O Control 360 Device which can be found in many (all ?) Sony Vaio laptops. 361 362 If you have one of those laptops, read 363 <file:Documentation/admin-guide/laptops/sonypi.rst>, and say Y or M here. 364 365 To compile this driver as a module, choose M here: the 366 module will be called sonypi. 367 368config GPIO_TB0219 369 tristate "TANBAC TB0219 GPIO support" 370 depends on TANBAC_TB022X 371 select GPIO_VR41XX 372 373source "drivers/char/pcmcia/Kconfig" 374 375config MWAVE 376 tristate "ACP Modem (Mwave) support" 377 depends on X86 && TTY 378 select SERIAL_8250 379 ---help--- 380 The ACP modem (Mwave) for Linux is a WinModem. It is composed of a 381 kernel driver and a user level application. Together these components 382 support direct attachment to public switched telephone networks (PSTNs) 383 and support selected world wide countries. 384 385 This version of the ACP Modem driver supports the IBM Thinkpad 600E, 386 600, and 770 that include on board ACP modem hardware. 387 388 The modem also supports the standard communications port interface 389 (ttySx) and is compatible with the Hayes AT Command Set. 390 391 The user level application needed to use this driver can be found at 392 the IBM Linux Technology Center (LTC) web site: 393 <http://www.ibm.com/linux/ltc/>. 394 395 If you own one of the above IBM Thinkpads which has the Mwave chipset 396 in it, say Y. 397 398 To compile this driver as a module, choose M here: the 399 module will be called mwave. 400 401config SCx200_GPIO 402 tristate "NatSemi SCx200 GPIO Support" 403 depends on SCx200 404 select NSC_GPIO 405 help 406 Give userspace access to the GPIO pins on the National 407 Semiconductor SCx200 processors. 408 409 If compiled as a module, it will be called scx200_gpio. 410 411config PC8736x_GPIO 412 tristate "NatSemi PC8736x GPIO Support" 413 depends on X86_32 && !UML 414 default SCx200_GPIO # mostly N 415 select NSC_GPIO # needed for support routines 416 help 417 Give userspace access to the GPIO pins on the National 418 Semiconductor PC-8736x (x=[03456]) SuperIO chip. The chip 419 has multiple functional units, inc several managed by 420 hwmon/pc87360 driver. Tested with PC-87366 421 422 If compiled as a module, it will be called pc8736x_gpio. 423 424config NSC_GPIO 425 tristate "NatSemi Base GPIO Support" 426 depends on X86_32 427 # selected by SCx200_GPIO and PC8736x_GPIO 428 # what about 2 selectors differing: m != y 429 help 430 Common support used (and needed) by scx200_gpio and 431 pc8736x_gpio drivers. If those drivers are built as 432 modules, this one will be too, named nsc_gpio 433 434config RAW_DRIVER 435 tristate "RAW driver (/dev/raw/rawN)" 436 depends on BLOCK 437 help 438 The raw driver permits block devices to be bound to /dev/raw/rawN. 439 Once bound, I/O against /dev/raw/rawN uses efficient zero-copy I/O. 440 See the raw(8) manpage for more details. 441 442 Applications should preferably open the device (eg /dev/hda1) 443 with the O_DIRECT flag. 444 445config MAX_RAW_DEVS 446 int "Maximum number of RAW devices to support (1-65536)" 447 depends on RAW_DRIVER 448 range 1 65536 449 default "256" 450 help 451 The maximum number of RAW devices that are supported. 452 Default is 256. Increase this number in case you need lots of 453 raw devices. 454 455config HPET 456 bool "HPET - High Precision Event Timer" if (X86 || IA64) 457 default n 458 depends on ACPI 459 help 460 If you say Y here, you will have a miscdevice named "/dev/hpet/". Each 461 open selects one of the timers supported by the HPET. The timers are 462 non-periodic and/or periodic. 463 464config HPET_MMAP 465 bool "Allow mmap of HPET" 466 default y 467 depends on HPET 468 help 469 If you say Y here, user applications will be able to mmap 470 the HPET registers. 471 472config HPET_MMAP_DEFAULT 473 bool "Enable HPET MMAP access by default" 474 default y 475 depends on HPET_MMAP 476 help 477 In some hardware implementations, the page containing HPET 478 registers may also contain other things that shouldn't be 479 exposed to the user. This option selects the default (if 480 kernel parameter hpet_mmap is not set) user access to the 481 registers for applications that require it. 482 483config HANGCHECK_TIMER 484 tristate "Hangcheck timer" 485 depends on X86 || IA64 || PPC64 || S390 486 help 487 The hangcheck-timer module detects when the system has gone 488 out to lunch past a certain margin. It can reboot the system 489 or merely print a warning. 490 491config UV_MMTIMER 492 tristate "UV_MMTIMER Memory mapped RTC for SGI UV" 493 depends on X86_UV 494 default m 495 help 496 The uv_mmtimer device allows direct userspace access to the 497 UV system timer. 498 499source "drivers/char/tpm/Kconfig" 500 501config TELCLOCK 502 tristate "Telecom clock driver for ATCA SBC" 503 depends on X86 504 default n 505 help 506 The telecom clock device is specific to the MPCBL0010 and MPCBL0050 507 ATCA computers and allows direct userspace access to the 508 configuration of the telecom clock configuration settings. This 509 device is used for hardware synchronization across the ATCA backplane 510 fabric. Upon loading, the driver exports a sysfs directory, 511 /sys/devices/platform/telco_clock, with a number of files for 512 controlling the behavior of this hardware. 513 514config DEVPORT 515 bool "/dev/port character device" 516 depends on ISA || PCI 517 default y 518 help 519 Say Y here if you want to support the /dev/port device. The /dev/port 520 device is similar to /dev/mem, but for I/O ports. 521 522source "drivers/s390/char/Kconfig" 523 524source "drivers/char/xillybus/Kconfig" 525 526config ADI 527 tristate "SPARC Privileged ADI driver" 528 depends on SPARC64 529 default m 530 help 531 SPARC M7 and newer processors utilize ADI (Application Data 532 Integrity) to version and protect memory. This driver provides 533 read/write access to the ADI versions for privileged processes. 534 This feature is also known as MCD (Memory Corruption Detection) 535 and SSM (Silicon Secured Memory). Intended consumers of this 536 driver include crash and makedumpfile. 537 538endmenu 539 540config RANDOM_TRUST_CPU 541 bool "Trust the CPU manufacturer to initialize Linux's CRNG" 542 depends on X86 || S390 || PPC 543 default n 544 help 545 Assume that CPU manufacturer (e.g., Intel or AMD for RDSEED or 546 RDRAND, IBM for the S390 and Power PC architectures) is trustworthy 547 for the purposes of initializing Linux's CRNG. Since this is not 548 something that can be independently audited, this amounts to trusting 549 that CPU manufacturer (perhaps with the insistence or mandate 550 of a Nation State's intelligence or law enforcement agencies) 551 has not installed a hidden back door to compromise the CPU's 552 random number generation facilities. This can also be configured 553 at boot with "random.trust_cpu=on/off". 554 555config RANDOM_TRUST_BOOTLOADER 556 bool "Trust the bootloader to initialize Linux's CRNG" 557 help 558 Some bootloaders can provide entropy to increase the kernel's initial 559 device randomness. Say Y here to assume the entropy provided by the 560 booloader is trustworthy so it will be added to the kernel's entropy 561 pool. Otherwise, say N here so it will be regarded as device input that 562 only mixes the entropy pool.
