linux/Documentation/pnp.txt
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   1Linux Plug and Play Documentation
   2by Adam Belay <ambx1@neo.rr.com>
   3last updated: Oct. 16, 2002
   4---------------------------------------------------------------------------------------
   5
   6
   7
   8Overview
   9--------
  10        Plug and Play provides a means of detecting and setting resources for legacy or
  11otherwise unconfigurable devices.  The Linux Plug and Play Layer provides these 
  12services to compatible drivers.
  13
  14
  15
  16The User Interface
  17------------------
  18        The Linux Plug and Play user interface provides a means to activate PnP devices
  19for legacy and user level drivers that do not support Linux Plug and Play.  The 
  20user interface is integrated into sysfs.
  21
  22In addition to the standard sysfs file the following are created in each
  23device's directory:
  24id - displays a list of support EISA IDs
  25options - displays possible resource configurations
  26resources - displays currently allocated resources and allows resource changes
  27
  28-activating a device
  29
  30#echo "auto" > resources
  31
  32this 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
  47EXAMPLE:
  48
  49Suppose you need to activate the floppy disk controller.
  501.) 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
  54PC standard floppy disk controller
  55
  562.) check if the device is already active
  57# cat resources
  58DISABLED
  59
  60- Notice the string "DISABLED".  This means the device is not active.
  61
  623.) check the device's possible configurations (optional)
  63# cat options
  64Dependent: 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
  69Dependent: 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
  754.) now activate the device
  76# echo "auto" > resources
  77
  785.) finally check if the device is active
  79# cat resources
  80io 0x3f0-0x3f5
  81io 0x3f7-0x3f7
  82irq 6
  83dma 2
  84
  85also there are a series of kernel parameters:
  86pnp_reserve_irq=irq1[,irq2] ....
  87pnp_reserve_dma=dma1[,dma2] ....
  88pnp_reserve_io=io1,size1[,io2,size2] ....
  89pnp_reserve_mem=mem1,size1[,mem2,size2] ....
  90
  91
  92
  93The Unified Plug and Play Layer
  94-------------------------------
  95        All Plug and Play drivers, protocols, and services meet at a central location 
  96called the Plug and Play Layer.  This layer is responsible for the exchange of 
  97information between PnP drivers and PnP protocols.  Thus it automatically 
  98forwards commands to the proper protocol.  This makes writing PnP drivers 
  99significantly easier.
 100
 101The following functions are available from the Plug and Play Layer:
 102
 103pnp_get_protocol
 104- increments the number of uses by one
 105
 106pnp_put_protocol
 107- deincrements the number of uses by one
 108
 109pnp_register_protocol
 110- use this to register a new PnP protocol
 111
 112pnp_unregister_protocol
 113- use this function to remove a PnP protocol from the Plug and Play Layer
 114
 115pnp_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
 122pnp_unregister_driver
 123- removes a PnP driver from the Plug and Play Layer
 124
 125
 126
 127Plug and Play Protocols
 128-----------------------
 129        This section contains information for PnP protocol developers.
 130
 131The 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 
 135devices.
 136It is meant to replace the PNPBIOS.  It is not currently supported by Linux
 137Plug and Play but it is planned to be in the near future.
 138
 139
 140Requirements for a Linux PnP protocol:
 1411.) the protocol must use EISA IDs
 1422.) the protocol must inform the PnP Layer of a device's current configuration
 143- the ability to set resources is optional but preferred.
 144
 145The following are PnP protocol related functions:
 146
 147pnp_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 
 150structure
 151
 152pnp_init_device
 153- call this to initialize the PnP structure
 154
 155pnp_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
 160pnp_add_id
 161- adds an EISA ID to the list of supported IDs for the specified device
 162
 163For more information consult the source of a protocol such as
 164/drivers/pnp/pnpbios/core.c.
 165
 166
 167
 168Linux Plug and Play Drivers
 169---------------------------
 170        This section contains information for Linux PnP driver developers.
 171
 172The New Way
 173...........
 1741.) first make a list of supported EISA IDS
 175ex:
 176static 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
 184Please note that the character 'X' can be used as a wild card in the function
 185portion (last four characters).
 186ex:
 187        /* Unknown PnP modems */
 188        {       "PNPCXXX",              UNKNOWN_DEV     },
 189
 190Supported PnP card IDs can optionally be defined.
 191ex:
 192static const struct pnp_id pnp_card_table[] = {
 193        {       "ANYDEVS",              0       },
 194        {       "",                     0       }
 195};
 196
 1972.) Optionally define probe and remove functions.  It may make sense not to 
 198define these functions if the driver already has a reliable method of detecting
 199the resources, such as the parport_pc driver.
 200ex:
 201static int
 202serial_pnp_probe(struct pnp_dev * dev, const struct pnp_id *card_id, const 
 203                 struct pnp_id *dev_id)
 204{
 205. . .
 206
 207ex:
 208static void serial_pnp_remove(struct pnp_dev * dev)
 209{
 210. . .
 211
 212consult /drivers/serial/8250_pnp.c for more information.
 213
 2143.) create a driver structure
 215ex:
 216
 217static 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
 2274.) register the driver
 228ex:
 229
 230static int __init serial8250_pnp_init(void)
 231{
 232        return pnp_register_driver(&serial_pnp_driver);
 233}
 234
 235The Old Way
 236...........
 237
 238A series of compatibility functions have been created to make it easy to convert
 239ISAPNP drivers.  They should serve as a temporary solution only.
 240
 241They are as follows:
 242
 243struct pnp_card *pnp_find_card(unsigned short vendor,
 244                                 unsigned short device,
 245                                 struct pnp_card *from)
 246
 247struct pnp_dev *pnp_find_dev(struct pnp_card *card,
 248                                unsigned short vendor,
 249                                unsigned short function,
 250                                struct pnp_dev *from)
 251
 252
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