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Based on kernel version 3.16. Page generated on 2014-08-06 21:40 EST.

1	Linux Plug and Play Documentation
2	by Adam Belay <ambx1@neo.rr.com>
3	last updated: Oct. 16, 2002
4	---------------------------------------------------------------------------------------
5	
6	
7	
8	Overview
9	--------
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.
13	
14	
15	
16	The User Interface
17	------------------
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 sysfs.
21	
22	In addition to the standard sysfs file the following are created in each
23	device's directory:
24	id - displays a list of support EISA IDs
25	options - displays possible resource configurations
26	resources - displays currently allocated resources and allows resource changes
27	
28	-activating a device
29	
30	#echo "auto" > resources
31	
32	this will invoke the automatic resource config system to activate the device
33	
34	-manually activating a device
35	
36	#echo "manual <depnum> <mode>" > resources
37	<depnum> - the configuration number
38	<mode> - static or dynamic
39			static = for next boot
40			dynamic = now
41	
42	-disabling a device
43	
44	#echo "disable" > resources
45	
46	
47	EXAMPLE:
48	
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
53	# cat name
54	PC standard floppy disk controller
55	
56	2.) check if the device is already active
57	# cat resources
58	DISABLED
59	
60	- Notice the string "DISABLED".  This means the device is not active.
61	
62	3.) check the device's possible configurations (optional)
63	# cat options
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
67	    irq 6
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
72	    irq 6
73	    dma 2 8-bit compatible
74	
75	4.) now activate the device
76	# echo "auto" > resources
77	
78	5.) finally check if the device is active
79	# cat resources
80	io 0x3f0-0x3f5
81	io 0x3f7-0x3f7
82	irq 6
83	dma 2
84	
85	also there are a series of kernel parameters:
86	pnp_reserve_irq=irq1[,irq2] ....
87	pnp_reserve_dma=dma1[,dma2] ....
88	pnp_reserve_io=io1,size1[,io2,size2] ....
89	pnp_reserve_mem=mem1,size1[,mem2,size2] ....
90	
91	
92	
93	The Unified Plug and Play Layer
94	-------------------------------
95		All Plug and Play drivers, protocols, and services meet at a central location 
96	called the Plug and Play Layer.  This layer is responsible for the exchange of 
97	information between PnP drivers and PnP protocols.  Thus it automatically 
98	forwards commands to the proper protocol.  This makes writing PnP drivers 
99	significantly easier.
100	
101	The following functions are available from the Plug and Play Layer:
102	
103	pnp_get_protocol
104	- increments the number of uses by one
105	
106	pnp_put_protocol
107	- deincrements the number of uses by one
108	
109	pnp_register_protocol
110	- use this to register a new PnP protocol
111	
112	pnp_unregister_protocol
113	- use this function to remove a PnP protocol from the Plug and Play Layer
114	
115	pnp_register_driver
116	- adds a PnP driver to the Plug and Play Layer
117	- this includes driver model integration
118	- returns zero for success or a negative error number for failure; count
119	  calls to the .add() method if you need to know how many devices bind to
120	  the driver
121	
122	pnp_unregister_driver
123	- removes a PnP driver from the Plug and Play Layer
124	
125	
126	
127	Plug and Play Protocols
128	-----------------------
129		This section contains information for PnP protocol developers.
130	
131	The following Protocols are currently available in the computing world:
132	- PNPBIOS: used for system devices such as serial and parallel ports.
133	- ISAPNP: provides PnP support for the ISA bus
134	- ACPI: among its many uses, ACPI provides information about system level 
135	devices.
136	It is meant to replace the PNPBIOS.  It is not currently supported by Linux
137	Plug and Play but it is planned to be in the near future.
138	
139	
140	Requirements for a Linux PnP protocol:
141	1.) the protocol must use EISA IDs
142	2.) the protocol must inform the PnP Layer of a device's current configuration
143	- the ability to set resources is optional but preferred.
144	
145	The following are PnP protocol related functions:
146	
147	pnp_add_device
148	- use this function to add a PnP device to the PnP layer
149	- only call this function when all wanted values are set in the pnp_dev 
150	structure
151	
152	pnp_init_device
153	- call this to initialize the PnP structure
154	
155	pnp_remove_device
156	- call this to remove a device from the Plug and Play Layer.
157	- it will fail if the device is still in use.
158	- automatically will free mem used by the device and related structures
159	
160	pnp_add_id
161	- adds an EISA ID to the list of supported IDs for the specified device
162	
163	For more information consult the source of a protocol such as
164	/drivers/pnp/pnpbios/core.c.
165	
166	
167	
168	Linux Plug and Play Drivers
169	---------------------------
170		This section contains information for Linux PnP driver developers.
171	
172	The New Way
173	...........
174	1.) first make a list of supported EISA IDS
175	ex:
176	static const struct pnp_id pnp_dev_table[] = {
177		/* Standard LPT Printer Port */
178		{.id = "PNP0400", .driver_data = 0},
179		/* ECP Printer Port */
180		{.id = "PNP0401", .driver_data = 0},
181		{.id = ""}
182	};
183	
184	Please note that the character 'X' can be used as a wild card in the function
185	portion (last four characters).
186	ex:
187		/* Unknown PnP modems */
188		{	"PNPCXXX",		UNKNOWN_DEV	},
189	
190	Supported PnP card IDs can optionally be defined.
191	ex:
192	static const struct pnp_id pnp_card_table[] = {
193		{	"ANYDEVS",		0	},
194		{	"",			0	}
195	};
196	
197	2.) Optionally define probe and remove functions.  It may make sense not to 
198	define these functions if the driver already has a reliable method of detecting
199	the resources, such as the parport_pc driver.
200	ex:
201	static int
202	serial_pnp_probe(struct pnp_dev * dev, const struct pnp_id *card_id, const 
203	                 struct pnp_id *dev_id)
204	{
205	. . .
206	
207	ex:
208	static void serial_pnp_remove(struct pnp_dev * dev)
209	{
210	. . .
211	
212	consult /drivers/serial/8250_pnp.c for more information.
213	
214	3.) create a driver structure
215	ex:
216	
217	static struct pnp_driver serial_pnp_driver = {
218		.name		= "serial",
219		.card_id_table	= pnp_card_table,
220		.id_table	= pnp_dev_table,
221		.probe		= serial_pnp_probe,
222		.remove		= serial_pnp_remove,
223	};
224	
225	* name and id_table cannot be NULL.
226	
227	4.) register the driver
228	ex:
229	
230	static int __init serial8250_pnp_init(void)
231	{
232		return pnp_register_driver(&serial_pnp_driver);
233	}
234	
235	The Old Way
236	...........
237	
238	A series of compatibility functions have been created to make it easy to convert
239	ISAPNP drivers.  They should serve as a temporary solution only.
240	
241	They are as follows:
242	
243	struct pnp_card *pnp_find_card(unsigned short vendor,
244					 unsigned short device,
245					 struct pnp_card *from)
246	
247	struct pnp_dev *pnp_find_dev(struct pnp_card *card,
248					unsigned short vendor,
249					unsigned short function,
250					struct pnp_dev *from)
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