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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_dev *pnp_find_dev(struct pnp_card *card,
285 unsigned short vendor,
286 unsigned short function,
287 struct pnp_dev *from)
288