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 <https://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 (<https://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 <https://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