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_register_driver 133 adds a PnP driver to the Plug and Play Layer 134 135 this includes driver model integration 136 returns zero for success or a negative error number for failure; count 137 calls to the .add() method if you need to know how many devices bind to 138 the driver 139 140pnp_unregister_driver 141 removes a PnP driver from the Plug and Play Layer 142 143 144 145Plug and Play Protocols 146----------------------- 147 148This section contains information for PnP protocol developers. 149 150The following Protocols are currently available in the computing world: 151 152- PNPBIOS: 153 used for system devices such as serial and parallel ports. 154- ISAPNP: 155 provides PnP support for the ISA bus 156- ACPI: 157 among its many uses, ACPI provides information about system level 158 devices. 159 160It is meant to replace the PNPBIOS. It is not currently supported by Linux 161Plug and Play but it is planned to be in the near future. 162 163 164Requirements for a Linux PnP protocol: 1651. the protocol must use EISA IDs 1662. the protocol must inform the PnP Layer of a device's current configuration 167 168- the ability to set resources is optional but preferred. 169 170The following are PnP protocol related functions: 171 172pnp_add_device 173 use this function to add a PnP device to the PnP layer 174 175 only call this function when all wanted values are set in the pnp_dev 176 structure 177 178pnp_init_device 179 call this to initialize the PnP structure 180 181pnp_remove_device 182 call this to remove a device from the Plug and Play Layer. 183 it will fail if the device is still in use. 184 automatically will free mem used by the device and related structures 185 186pnp_add_id 187 adds an EISA ID to the list of supported IDs for the specified device 188 189For more information consult the source of a protocol such as 190/drivers/pnp/pnpbios/core.c. 191 192 193 194Linux Plug and Play Drivers 195--------------------------- 196 197This section contains information for Linux PnP driver developers. 198 199The New Way 200^^^^^^^^^^^ 201 2021. first make a list of supported EISA IDS 203 204 ex:: 205 206 static const struct pnp_id pnp_dev_table[] = { 207 /* Standard LPT Printer Port */ 208 {.id = "PNP0400", .driver_data = 0}, 209 /* ECP Printer Port */ 210 {.id = "PNP0401", .driver_data = 0}, 211 {.id = ""} 212 }; 213 214 Please note that the character 'X' can be used as a wild card in the function 215 portion (last four characters). 216 217 ex:: 218 219 /* Unknown PnP modems */ 220 { "PNPCXXX", UNKNOWN_DEV }, 221 222 Supported PnP card IDs can optionally be defined. 223 ex:: 224 225 static const struct pnp_id pnp_card_table[] = { 226 { "ANYDEVS", 0 }, 227 { "", 0 } 228 }; 229 2302. Optionally define probe and remove functions. It may make sense not to 231 define these functions if the driver already has a reliable method of detecting 232 the resources, such as the parport_pc driver. 233 234 ex:: 235 236 static int 237 serial_pnp_probe(struct pnp_dev * dev, const struct pnp_id *card_id, const 238 struct pnp_id *dev_id) 239 { 240 . . . 241 242 ex:: 243 244 static void serial_pnp_remove(struct pnp_dev * dev) 245 { 246 . . . 247 248 consult /drivers/serial/8250_pnp.c for more information. 249 2503. create a driver structure 251 252 ex:: 253 254 static struct pnp_driver serial_pnp_driver = { 255 .name = "serial", 256 .card_id_table = pnp_card_table, 257 .id_table = pnp_dev_table, 258 .probe = serial_pnp_probe, 259 .remove = serial_pnp_remove, 260 }; 261 262 * name and id_table cannot be NULL. 263 2644. register the driver 265 266 ex:: 267 268 static int __init serial8250_pnp_init(void) 269 { 270 return pnp_register_driver(&serial_pnp_driver); 271 } 272 273The Old Way 274^^^^^^^^^^^ 275 276A series of compatibility functions have been created to make it easy to convert 277ISAPNP drivers. They should serve as a temporary solution only. 278 279They are as follows:: 280 281 struct pnp_dev *pnp_find_dev(struct pnp_card *card, 282 unsigned short vendor, 283 unsigned short function, 284 struct pnp_dev *from) 285 286