1 Linux Plug and Play Documentation
2 by Adam Belay <ambx1@neo.rr.com>
3 last updated: Oct. 16, 2002
4 ---------------------------------------------------------------------------------------
10 Plug and Play provides a means of detecting and setting resources for legacy or
11 otherwise unconfigurable devices. The Linux Plug and Play Layer provides these
12 services to compatible drivers.
18 The Linux Plug and Play user interface provides a means to activate PnP devices
19 for legacy and user level drivers that do not support Linux Plug and Play. The
20 user interface is integrated into driverfs.
22 In addition to the standard driverfs file the following are created in each
24 id - displays a list of support EISA IDs
25 possible - displays possible resource configurations
26 resources - displays currently allocated resources and allows resource changes
30 #echo "auto" > resources
32 this will invoke the automatic resource config system to activate the device
34 -manually activating a device
36 #echo "manual <depnum> <mode>" > resources
37 <depnum> - the configuration number
38 <mode> - static or dynamic
39 static = for next boot
44 #echo "disable" > resources
49 Suppose you need to activate the floppy disk controller.
50 1.) change to the proper directory, in my case it is
51 /driver/bus/pnp/devices/00:0f
52 # cd /driver/bus/pnp/devices/00:0f
54 PC standard floppy disk controller
56 2.) check if the device is already active
60 - Notice the string "DISABLED". THis means the device is not active.
62 3.) check the device's possible configurations (optional)
64 Dependent: 01 - Priority acceptable
65 port 0x3f0-0x3f0, align 0x7, size 0x6, 16-bit address decoding
66 port 0x3f7-0x3f7, align 0x0, size 0x1, 16-bit address decoding
68 dma 2 8-bit compatible
69 Dependent: 02 - Priority acceptable
70 port 0x370-0x370, align 0x7, size 0x6, 16-bit address decoding
71 port 0x377-0x377, align 0x0, size 0x1, 16-bit address decoding
73 dma 2 8-bit compatible
75 4.) now activate the device
76 # echo "auto" > resources
78 5.) finally check if the device is active
85 also there are a series of kernel parameters:
87 pnp_reserve_irq=irq1[,irq2] ....
88 pnp_reserve_dma=dma1[,dma2] ....
89 pnp_reserve_io=io1,size1[,io2,size2] ....
90 pnp_reserve_mem=mem1,size1[,mem2,size2] ....
94 The Unified Plug and Play Layer
95 -------------------------------
96 All Plug and Play drivers, protocols, and services meet at a central location
97 called the Plug and Play Layer. This layer is responsible for the exchange of
98 information between PnP drivers and PnP protocols. Thus it automatically
99 forwards commands to the proper protocol. This makes writing PnP drivers
100 significantly easier.
102 The following functions are available from the Plug and Play Layer:
105 - increments the number of uses by one
108 - deincrements the number of uses by one
110 pnp_register_protocol
111 - use this to register a new PnP protocol
113 pnp_unregister_protocol
114 - use this function to remove a PnP protocol from the Plug and Play Layer
117 - adds a PnP driver to the Plug and Play Layer
118 - this includes driver model integration
120 pnp_unregister_driver
121 - removes a PnP driver from the Plug and Play Layer
125 Plug and Play Protocols
126 -----------------------
127 This section contains information for PnP protocol developers.
129 The following Protocols are currently available in the computing world:
130 - PNPBIOS: used for system devices such as serial and parallel ports.
131 - ISAPNP: provides PnP support for the ISA bus
132 - ACPI: among its many uses, ACPI provides information about system level
134 It is meant to replace the PNPBIOS. It is not currently supported by Linux
135 Plug and Play but it is planned to be in the near future.
138 Requirements for a Linux PnP protocol:
139 1.) the protocol must use EISA IDs
140 2.) the protocol must inform the PnP Layer of a devices current configuration
141 - the ability to set resources is optional but prefered.
143 The following are PnP protocol related functions:
146 - use this function to add a PnP device to the PnP layer
147 - only call this function when all wanted values are set in the pnp_dev
151 - call this to initialize the PnP structure
154 - call this to remove a device from the Plug and Play Layer.
155 - it will fail if the device is still in use.
156 - automatically will free mem used by the device and related structures
159 - adds a EISA ID to the list of supported IDs for the specified device
161 For more information consult the source of a protocol such as
162 /drivers/pnp/pnpbios/core.c.
166 Linux Plug and Play Drivers
167 ---------------------------
168 This section contains information for linux PnP driver developers.
172 1.) first make a list of supported EISA IDS
174 static const struct pnp_id pnp_dev_table[] = {
175 /* Standard LPT Printer Port */
176 {.id = "PNP0400", .driver_data = 0},
177 /* ECP Printer Port */
178 {.id = "PNP0401", .driver_data = 0},
182 Please note that the character 'X' can be used as a wild card in the function
183 portion (last four characters).
185 /* Unkown PnP modems */
186 { "PNPCXXX", UNKNOWN_DEV },
188 Supported PnP card IDs can optionally be defined.
190 static const struct pnp_id pnp_card_table[] = {
195 2.) Optionally define probe and remove functions. It may make sense not to
196 define these functions if the driver already has a reliable method of detecting
197 the resources, such as the parport_pc driver.
200 serial_pnp_probe(struct pnp_dev * dev, const struct pnp_id *card_id, const
201 struct pnp_id *dev_id)
206 static void serial_pnp_remove(struct pnp_dev * dev)
210 consult /drivers/serial/8250_pnp.c for more information.
212 3.) create a driver structure
215 static struct pnp_driver serial_pnp_driver = {
217 .card_id_table = pnp_card_table,
218 .id_table = pnp_dev_table,
219 .probe = serial_pnp_probe,
220 .remove = serial_pnp_remove,
223 * name and id_table can not be NULL.
225 4.) register the driver
228 static int __init serial8250_pnp_init(void)
230 return pnp_register_driver(&serial_pnp_driver);
236 a series of compatibility functions have been created to make it easy to convert
238 ISAPNP drivers. They should serve as a temporary solution only.
242 struct pnp_card *pnp_find_card(unsigned short vendor,
243 unsigned short device,
244 struct pnp_card *from)
246 struct pnp_dev *pnp_find_dev(struct pnp_card *card,
247 unsigned short vendor,
248 unsigned short function,
249 struct pnp_dev *from)