Documentation/admin-guide/pnp.rst - linux - Git at Google

 =================================
 Linux Plug and Play Documentation
 =================================

 :Author: Adam Belay <ambx1@neo.rr.com>
 :Last updated: Oct. 16, 2002


 Overview
 --------

 Plug and Play provides a means of detecting and setting resources for legacy or
 otherwise unconfigurable devices.  The Linux Plug and Play Layer provides these
 services to compatible drivers.


 The User Interface
 ------------------

 The Linux Plug and Play user interface provides a means to activate PnP devices
 for legacy and user level drivers that do not support Linux Plug and Play.  The
 user interface is integrated into sysfs.

 In addition to the standard sysfs file the following are created in each
 device's directory:
 - id - displays a list of support EISA IDs
 - options - displays possible resource configurations
 - resources - displays currently allocated resources and allows resource changes

 activating a device
 ^^^^^^^^^^^^^^^^^^^

 ::

 	# echo "auto" > resources

 this will invoke the automatic resource config system to activate the device

 manually activating a device
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^

 ::

 	# echo "manual <depnum> <mode>" > resources

 	<depnum> - the configuration number
 	<mode> - static or dynamic
 		 static = for next boot
 		 dynamic = now

 disabling a device
 ^^^^^^^^^^^^^^^^^^

 ::

 	# echo "disable" > resources


 EXAMPLE:

 Suppose you need to activate the floppy disk controller.

 1. change to the proper directory, in my case it is
    /driver/bus/pnp/devices/00:0f::

 	# cd /driver/bus/pnp/devices/00:0f
 	# cat name
 	PC standard floppy disk controller

 2. check if the device is already active::

 	# cat resources
 	DISABLED

   - Notice the string "DISABLED".  This means the device is not active.

 3. check the device's possible configurations (optional)::

 	# cat options
 	Dependent: 01 - Priority acceptable
 	    port 0x3f0-0x3f0, align 0x7, size 0x6, 16-bit address decoding
 	    port 0x3f7-0x3f7, align 0x0, size 0x1, 16-bit address decoding
 	    irq 6
 	    dma 2 8-bit compatible
 	Dependent: 02 - Priority acceptable
 	    port 0x370-0x370, align 0x7, size 0x6, 16-bit address decoding
 	    port 0x377-0x377, align 0x0, size 0x1, 16-bit address decoding
 	    irq 6
 	    dma 2 8-bit compatible

 4. now activate the device::

 	# echo "auto" > resources

 5. finally check if the device is active::

 	# cat resources
 	io 0x3f0-0x3f5
 	io 0x3f7-0x3f7
 	irq 6
 	dma 2

 also there are a series of kernel parameters::

 	pnp_reserve_irq=irq1[,irq2] ....
 	pnp_reserve_dma=dma1[,dma2] ....
 	pnp_reserve_io=io1,size1[,io2,size2] ....
 	pnp_reserve_mem=mem1,size1[,mem2,size2] ....


 The Unified Plug and Play Layer
 -------------------------------

 All Plug and Play drivers, protocols, and services meet at a central location
 called the Plug and Play Layer.  This layer is responsible for the exchange of
 information between PnP drivers and PnP protocols.  Thus it automatically
 forwards commands to the proper protocol.  This makes writing PnP drivers
 significantly easier.

 The following functions are available from the Plug and Play Layer:

 pnp_get_protocol
   increments the number of uses by one

 pnp_put_protocol
   deincrements the number of uses by one

 pnp_register_protocol
   use this to register a new PnP protocol

 pnp_unregister_protocol
   use this function to remove a PnP protocol from the Plug and Play Layer

 pnp_register_driver
   adds a PnP driver to the Plug and Play Layer

   this includes driver model integration
   returns zero for success or a negative error number for failure; count
   calls to the .add() method if you need to know how many devices bind to
   the driver

 pnp_unregister_driver
   removes a PnP driver from the Plug and Play Layer


 Plug and Play Protocols
 -----------------------

 This section contains information for PnP protocol developers.

 The following Protocols are currently available in the computing world:

 - PNPBIOS:
     used for system devices such as serial and parallel ports.
 - ISAPNP:
     provides PnP support for the ISA bus
 - ACPI:
     among its many uses, ACPI provides information about system level
     devices.

 It is meant to replace the PNPBIOS.  It is not currently supported by Linux
 Plug and Play but it is planned to be in the near future.


 Requirements for a Linux PnP protocol:
 1. the protocol must use EISA IDs
 2. the protocol must inform the PnP Layer of a device's current configuration

 - the ability to set resources is optional but preferred.

 The following are PnP protocol related functions:

 pnp_add_device
   use this function to add a PnP device to the PnP layer

   only call this function when all wanted values are set in the pnp_dev
   structure

 pnp_init_device
   call this to initialize the PnP structure

 pnp_remove_device
   call this to remove a device from the Plug and Play Layer.
   it will fail if the device is still in use.
   automatically will free mem used by the device and related structures

 pnp_add_id
   adds an EISA ID to the list of supported IDs for the specified device

 For more information consult the source of a protocol such as
 /drivers/pnp/pnpbios/core.c.


 Linux Plug and Play Drivers
 ---------------------------

 This section contains information for Linux PnP driver developers.

 The New Way
 ^^^^^^^^^^^

 1. first make a list of supported EISA IDS

    ex::

 	static const struct pnp_id pnp_dev_table[] = {
 		/* Standard LPT Printer Port */
 		{.id = "PNP0400", .driver_data = 0},
 		/* ECP Printer Port */
 		{.id = "PNP0401", .driver_data = 0},
 		{.id = ""}
 	};

    Please note that the character 'X' can be used as a wild card in the function
    portion (last four characters).

    ex::

 	/* Unknown PnP modems */
 	{	"PNPCXXX",		UNKNOWN_DEV	},

    Supported PnP card IDs can optionally be defined.
    ex::

 	static const struct pnp_id pnp_card_table[] = {
 		{	"ANYDEVS",		0	},
 		{	"",			0	}
 	};

 2. Optionally define probe and remove functions.  It may make sense not to
    define these functions if the driver already has a reliable method of detecting
    the resources, such as the parport_pc driver.

    ex::

 	static int
 	serial_pnp_probe(struct pnp_dev * dev, const struct pnp_id *card_id, const
 			struct pnp_id *dev_id)
 	{
 	. . .

    ex::

 	static void serial_pnp_remove(struct pnp_dev * dev)
 	{
 	. . .

    consult /drivers/serial/8250_pnp.c for more information.

 3. create a driver structure

    ex::

 	static struct pnp_driver serial_pnp_driver = {
 		.name		= "serial",
 		.card_id_table	= pnp_card_table,
 		.id_table	= pnp_dev_table,
 		.probe		= serial_pnp_probe,
 		.remove		= serial_pnp_remove,
 	};

    * name and id_table cannot be NULL.

 4. register the driver

    ex::

 	static int __init serial8250_pnp_init(void)
 	{
 		return pnp_register_driver(&serial_pnp_driver);
 	}

 The Old Way
 ^^^^^^^^^^^

 A series of compatibility functions have been created to make it easy to convert
 ISAPNP drivers.  They should serve as a temporary solution only.

 They are as follows::

 	struct pnp_dev *pnp_find_dev(struct pnp_card *card,
 				     unsigned short vendor,
 				     unsigned short function,
 				     struct pnp_dev *from)
	=================================
	Linux Plug and Play Documentation
	=================================

	:Author: Adam Belay <ambx1@neo.rr.com>
	:Last updated: Oct. 16, 2002


	Overview
	--------

	Plug and Play provides a means of detecting and setting resources for legacy or
	otherwise unconfigurable devices. The Linux Plug and Play Layer provides these
	services to compatible drivers.


	The User Interface
	------------------

	The Linux Plug and Play user interface provides a means to activate PnP devices
	for legacy and user level drivers that do not support Linux Plug and Play. The
	user interface is integrated into sysfs.

	In addition to the standard sysfs file the following are created in each
	device's directory:
	- id - displays a list of support EISA IDs
	- options - displays possible resource configurations
	- resources - displays currently allocated resources and allows resource changes

	activating a device
	^^^^^^^^^^^^^^^^^^^

	::

	# echo "auto" > resources

	this will invoke the automatic resource config system to activate the device

	manually activating a device
	^^^^^^^^^^^^^^^^^^^^^^^^^^^^

	::

	# echo "manual <depnum> <mode>" > resources

	<depnum> - the configuration number
	<mode> - static or dynamic
	static = for next boot
	dynamic = now

	disabling a device
	^^^^^^^^^^^^^^^^^^

	::

	# echo "disable" > resources


	EXAMPLE:

	Suppose you need to activate the floppy disk controller.

	1. change to the proper directory, in my case it is
	/driver/bus/pnp/devices/00:0f::

	# cd /driver/bus/pnp/devices/00:0f
	# cat name
	PC standard floppy disk controller

	2. check if the device is already active::

	# cat resources
	DISABLED

	- Notice the string "DISABLED". This means the device is not active.

	3. check the device's possible configurations (optional)::

	# cat options
	Dependent: 01 - Priority acceptable
	port 0x3f0-0x3f0, align 0x7, size 0x6, 16-bit address decoding
	port 0x3f7-0x3f7, align 0x0, size 0x1, 16-bit address decoding
	irq 6
	dma 2 8-bit compatible
	Dependent: 02 - Priority acceptable
	port 0x370-0x370, align 0x7, size 0x6, 16-bit address decoding
	port 0x377-0x377, align 0x0, size 0x1, 16-bit address decoding
	irq 6
	dma 2 8-bit compatible

	4. now activate the device::

	# echo "auto" > resources

	5. finally check if the device is active::

	# cat resources
	io 0x3f0-0x3f5
	io 0x3f7-0x3f7
	irq 6
	dma 2

	also there are a series of kernel parameters::

	pnp_reserve_irq=irq1[,irq2] ....
	pnp_reserve_dma=dma1[,dma2] ....
	pnp_reserve_io=io1,size1[,io2,size2] ....
	pnp_reserve_mem=mem1,size1[,mem2,size2] ....



	The Unified Plug and Play Layer
	-------------------------------

	All Plug and Play drivers, protocols, and services meet at a central location
	called the Plug and Play Layer. This layer is responsible for the exchange of
	information between PnP drivers and PnP protocols. Thus it automatically
	forwards commands to the proper protocol. This makes writing PnP drivers
	significantly easier.

	The following functions are available from the Plug and Play Layer:

	pnp_get_protocol
	increments the number of uses by one

	pnp_put_protocol
	deincrements the number of uses by one

	pnp_register_protocol
	use this to register a new PnP protocol

	pnp_unregister_protocol
	use this function to remove a PnP protocol from the Plug and Play Layer

	pnp_register_driver
	adds a PnP driver to the Plug and Play Layer

	this includes driver model integration
	returns zero for success or a negative error number for failure; count
	calls to the .add() method if you need to know how many devices bind to
	the driver

	pnp_unregister_driver
	removes a PnP driver from the Plug and Play Layer



	Plug and Play Protocols
	-----------------------

	This section contains information for PnP protocol developers.

	The following Protocols are currently available in the computing world:

	- PNPBIOS:
	used for system devices such as serial and parallel ports.
	- ISAPNP:
	provides PnP support for the ISA bus
	- ACPI:
	among its many uses, ACPI provides information about system level
	devices.

	It is meant to replace the PNPBIOS. It is not currently supported by Linux
	Plug and Play but it is planned to be in the near future.


	Requirements for a Linux PnP protocol:
	1. the protocol must use EISA IDs
	2. the protocol must inform the PnP Layer of a device's current configuration

	- the ability to set resources is optional but preferred.

	The following are PnP protocol related functions:

	pnp_add_device
	use this function to add a PnP device to the PnP layer

	only call this function when all wanted values are set in the pnp_dev
	structure

	pnp_init_device
	call this to initialize the PnP structure

	pnp_remove_device
	call this to remove a device from the Plug and Play Layer.
	it will fail if the device is still in use.
	automatically will free mem used by the device and related structures

	pnp_add_id
	adds an EISA ID to the list of supported IDs for the specified device

	For more information consult the source of a protocol such as
	/drivers/pnp/pnpbios/core.c.



	Linux Plug and Play Drivers
	---------------------------

	This section contains information for Linux PnP driver developers.

	The New Way
	^^^^^^^^^^^

	1. first make a list of supported EISA IDS

	ex::

	static const struct pnp_id pnp_dev_table[] = {
	/* Standard LPT Printer Port */
	{.id = "PNP0400", .driver_data = 0},
	/* ECP Printer Port */
	{.id = "PNP0401", .driver_data = 0},
	{.id = ""}
	};

	Please note that the character 'X' can be used as a wild card in the function
	portion (last four characters).

	ex::

	/* Unknown PnP modems */
	{ "PNPCXXX", UNKNOWN_DEV },

	Supported PnP card IDs can optionally be defined.
	ex::

	static const struct pnp_id pnp_card_table[] = {
	{ "ANYDEVS", 0 },
	{ "", 0 }
	};

	2. Optionally define probe and remove functions. It may make sense not to
	define these functions if the driver already has a reliable method of detecting
	the resources, such as the parport_pc driver.

	ex::

	static int
	serial_pnp_probe(struct pnp_dev * dev, const struct pnp_id *card_id, const
	struct pnp_id *dev_id)
	{
	. . .

	ex::

	static void serial_pnp_remove(struct pnp_dev * dev)
	{
	. . .

	consult /drivers/serial/8250_pnp.c for more information.

	3. create a driver structure

	ex::

	static struct pnp_driver serial_pnp_driver = {
	.name = "serial",
	.card_id_table = pnp_card_table,
	.id_table = pnp_dev_table,
	.probe = serial_pnp_probe,
	.remove = serial_pnp_remove,
	};

	* name and id_table cannot be NULL.

	4. register the driver

	ex::

	static int __init serial8250_pnp_init(void)
	{
	return pnp_register_driver(&serial_pnp_driver);
	}

	The Old Way
	^^^^^^^^^^^

	A series of compatibility functions have been created to make it easy to convert
	ISAPNP drivers. They should serve as a temporary solution only.

	They are as follows::

	struct pnp_dev pnp_find_dev(struct pnp_card card,
	unsigned short vendor,
	unsigned short function,
	struct pnp_dev *from)