linux/Documentation/pnp.txt
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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_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)
 292
 293