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Based on kernel version 4.13.3. Page generated on 2017-09-23 13:55 EST.

1	=================================
2	Linux Plug and Play Documentation
3	=================================
4	
5	:Author: Adam Belay <ambx1@neo.rr.com>
6	:Last updated: Oct. 16, 2002
7	
8	
9	Overview
10	--------
11	
12	Plug and Play provides a means of detecting and setting resources for legacy or
13	otherwise unconfigurable devices.  The Linux Plug and Play Layer provides these 
14	services to compatible drivers.
15	
16	
17	The User Interface
18	------------------
19	
20	The Linux Plug and Play user interface provides a means to activate PnP devices
21	for legacy and user level drivers that do not support Linux Plug and Play.  The 
22	user interface is integrated into sysfs.
23	
24	In addition to the standard sysfs file the following are created in each
25	device'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	
30	activating a device
31	^^^^^^^^^^^^^^^^^^^
32	
33	::
34	
35		# echo "auto" > resources
36	
37	this will invoke the automatic resource config system to activate the device
38	
39	manually 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	
51	disabling a device
52	^^^^^^^^^^^^^^^^^^
53	
54	::
55	
56		# echo "disable" > resources
57	
58	
59	EXAMPLE:
60	
61	Suppose you need to activate the floppy disk controller.
62	
63	1. 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	
70	2. 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	
77	3. 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	
91	4. now activate the device::
92	
93		# echo "auto" > resources
94	
95	5. 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	
103	also 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	
112	The Unified Plug and Play Layer
113	-------------------------------
114	
115	All Plug and Play drivers, protocols, and services meet at a central location
116	called the Plug and Play Layer.  This layer is responsible for the exchange of 
117	information between PnP drivers and PnP protocols.  Thus it automatically 
118	forwards commands to the proper protocol.  This makes writing PnP drivers 
119	significantly easier.
120	
121	The following functions are available from the Plug and Play Layer:
122	
123	pnp_get_protocol
124	  increments the number of uses by one
125	
126	pnp_put_protocol
127	  deincrements the number of uses by one
128	
129	pnp_register_protocol
130	  use this to register a new PnP protocol
131	
132	pnp_unregister_protocol
133	  use this function to remove a PnP protocol from the Plug and Play Layer
134	
135	pnp_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	
143	pnp_unregister_driver
144	  removes a PnP driver from the Plug and Play Layer
145	
146	
147	
148	Plug and Play Protocols
149	-----------------------
150	
151	This section contains information for PnP protocol developers.
152	
153	The 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	
163	It is meant to replace the PNPBIOS.  It is not currently supported by Linux
164	Plug and Play but it is planned to be in the near future.
165	
166	
167	Requirements for a Linux PnP protocol:
168	1. the protocol must use EISA IDs
169	2. 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	
173	The following are PnP protocol related functions:
174	
175	pnp_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	
181	pnp_init_device
182	  call this to initialize the PnP structure
183	
184	pnp_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	
189	pnp_add_id
190	  adds an EISA ID to the list of supported IDs for the specified device
191	
192	For more information consult the source of a protocol such as
193	/drivers/pnp/pnpbios/core.c.
194	
195	
196	
197	Linux Plug and Play Drivers
198	---------------------------
199	
200	This section contains information for Linux PnP driver developers.
201	
202	The New Way
203	^^^^^^^^^^^
204	
205	1. 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	
233	2. 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	
253	3. 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	
267	4. 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	
276	The Old Way
277	^^^^^^^^^^^
278	
279	A series of compatibility functions have been created to make it easy to convert
280	ISAPNP drivers.  They should serve as a temporary solution only.
281	
282	They 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)
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