1================================= 2Linux Plug and Play Documentation 3================================= 4 5:Author: Adam Belay <ambx1@neo.rr.com> 6:Last updated: Oct. 16, 2002 7 8 9Overview 10-------- 11 12Plug and Play provides a means of detecting and setting resources for legacy or 13otherwise unconfigurable devices. The Linux Plug and Play Layer provides these 14services to compatible drivers. 15 16 17The User Interface 18------------------ 19 20The Linux Plug and Play user interface provides a means to activate PnP devices 21for legacy and user level drivers that do not support Linux Plug and Play. The 22user interface is integrated into sysfs. 23 24In addition to the standard sysfs file the following are created in each 25device's directory: 26- id - displays a list of support EISA IDs 27- options - displays possible resource configurations 28- resources - displays currently allocated resources and allows resource changes 29 30activating a device 31^^^^^^^^^^^^^^^^^^^ 32 33:: 34 35 # echo "auto" > resources 36 37this will invoke the automatic resource config system to activate the device 38 39manually activating a device 40^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 41 42:: 43 44 # echo "manual <depnum> <mode>" > resources 45 46 <depnum> - the configuration number 47 <mode> - static or dynamic 48 static = for next boot 49 dynamic = now 50 51disabling a device 52^^^^^^^^^^^^^^^^^^ 53 54:: 55 56 # echo "disable" > resources 57 58 59EXAMPLE: 60 61Suppose you need to activate the floppy disk controller. 62 631. change to the proper directory, in my case it is 64 /driver/bus/pnp/devices/00:0f:: 65 66 # cd /driver/bus/pnp/devices/00:0f 67 # cat name 68 PC standard floppy disk controller 69 702. check if the device is already active:: 71 72 # cat resources 73 DISABLED 74 75 - Notice the string "DISABLED". This means the device is not active. 76 773. check the device's possible configurations (optional):: 78 79 # cat options 80 Dependent: 01 - Priority acceptable 81 port 0x3f0-0x3f0, align 0x7, size 0x6, 16-bit address decoding 82 port 0x3f7-0x3f7, align 0x0, size 0x1, 16-bit address decoding 83 irq 6 84 dma 2 8-bit compatible 85 Dependent: 02 - Priority acceptable 86 port 0x370-0x370, align 0x7, size 0x6, 16-bit address decoding 87 port 0x377-0x377, align 0x0, size 0x1, 16-bit address decoding 88 irq 6 89 dma 2 8-bit compatible 90 914. now activate the device:: 92 93 # echo "auto" > resources 94 955. finally check if the device is active:: 96 97 # cat resources 98 io 0x3f0-0x3f5 99 io 0x3f7-0x3f7 100 irq 6 101 dma 2 102 103also there are a series of kernel parameters:: 104 105 pnp_reserve_irq=irq1[,irq2] .... 106 pnp_reserve_dma=dma1[,dma2] .... 107 pnp_reserve_io=io1,size1[,io2,size2] .... 108 pnp_reserve_mem=mem1,size1[,mem2,size2] .... 109 110 111 112The Unified Plug and Play Layer 113------------------------------- 114 115All Plug and Play drivers, protocols, and services meet at a central location 116called the Plug and Play Layer. This layer is responsible for the exchange of 117information between PnP drivers and PnP protocols. Thus it automatically 118forwards commands to the proper protocol. This makes writing PnP drivers 119significantly easier. 120 121The following functions are available from the Plug and Play Layer: 122 123pnp_get_protocol 124 increments the number of uses by one 125 126pnp_put_protocol 127 deincrements the number of uses by one 128 129pnp_register_protocol 130 use this to register a new PnP protocol 131 132pnp_unregister_protocol 133 use this function to remove a PnP protocol from the Plug and Play Layer 134 135pnp_register_driver 136 adds a PnP driver to the Plug and Play Layer 137 138 this includes driver model integration 139 returns zero for success or a negative error number for failure; count 140 calls to the .add() method if you need to know how many devices bind to 141 the driver 142 143pnp_unregister_driver 144 removes a PnP driver from the Plug and Play Layer 145 146 147 148Plug and Play Protocols 149----------------------- 150 151This section contains information for PnP protocol developers. 152 153The following Protocols are currently available in the computing world: 154 155- PNPBIOS: 156 used for system devices such as serial and parallel ports. 157- ISAPNP: 158 provides PnP support for the ISA bus 159- ACPI: 160 among its many uses, ACPI provides information about system level 161 devices. 162 163It is meant to replace the PNPBIOS. It is not currently supported by Linux 164Plug and Play but it is planned to be in the near future. 165 166 167Requirements for a Linux PnP protocol: 1681. the protocol must use EISA IDs 1692. the protocol must inform the PnP Layer of a device's current configuration 170 171- the ability to set resources is optional but preferred. 172 173The following are PnP protocol related functions: 174 175pnp_add_device 176 use this function to add a PnP device to the PnP layer 177 178 only call this function when all wanted values are set in the pnp_dev 179 structure 180 181pnp_init_device 182 call this to initialize the PnP structure 183 184pnp_remove_device 185 call this to remove a device from the Plug and Play Layer. 186 it will fail if the device is still in use. 187 automatically will free mem used by the device and related structures 188 189pnp_add_id 190 adds an EISA ID to the list of supported IDs for the specified device 191 192For more information consult the source of a protocol such as 193/drivers/pnp/pnpbios/core.c. 194 195 196 197Linux Plug and Play Drivers 198--------------------------- 199 200This section contains information for Linux PnP driver developers. 201 202The New Way 203^^^^^^^^^^^ 204 2051. first make a list of supported EISA IDS 206 207 ex:: 208 209 static const struct pnp_id pnp_dev_table[] = { 210 /* Standard LPT Printer Port */ 211 {.id = "PNP0400", .driver_data = 0}, 212 /* ECP Printer Port */ 213 {.id = "PNP0401", .driver_data = 0}, 214 {.id = ""} 215 }; 216 217 Please note that the character 'X' can be used as a wild card in the function 218 portion (last four characters). 219 220 ex:: 221 222 /* Unknown PnP modems */ 223 { "PNPCXXX", UNKNOWN_DEV }, 224 225 Supported PnP card IDs can optionally be defined. 226 ex:: 227 228 static const struct pnp_id pnp_card_table[] = { 229 { "ANYDEVS", 0 }, 230 { "", 0 } 231 }; 232 2332. Optionally define probe and remove functions. It may make sense not to 234 define these functions if the driver already has a reliable method of detecting 235 the resources, such as the parport_pc driver. 236 237 ex:: 238 239 static int 240 serial_pnp_probe(struct pnp_dev * dev, const struct pnp_id *card_id, const 241 struct pnp_id *dev_id) 242 { 243 . . . 244 245 ex:: 246 247 static void serial_pnp_remove(struct pnp_dev * dev) 248 { 249 . . . 250 251 consult /drivers/serial/8250_pnp.c for more information. 252 2533. create a driver structure 254 255 ex:: 256 257 static struct pnp_driver serial_pnp_driver = { 258 .name = "serial", 259 .card_id_table = pnp_card_table, 260 .id_table = pnp_dev_table, 261 .probe = serial_pnp_probe, 262 .remove = serial_pnp_remove, 263 }; 264 265 * name and id_table cannot be NULL. 266 2674. register the driver 268 269 ex:: 270 271 static int __init serial8250_pnp_init(void) 272 { 273 return pnp_register_driver(&serial_pnp_driver); 274 } 275 276The Old Way 277^^^^^^^^^^^ 278 279A series of compatibility functions have been created to make it easy to convert 280ISAPNP drivers. They should serve as a temporary solution only. 281 282They are as follows:: 283 284 struct pnp_card *pnp_find_card(unsigned short vendor, 285 unsigned short device, 286 struct pnp_card *from) 287 288 struct pnp_dev *pnp_find_dev(struct pnp_card *card, 289 unsigned short vendor, 290 unsigned short function, 291 struct pnp_dev *from) 292 293
