Add qemu 2.4.0
[kvmfornfv.git] / qemu / roms / ipxe / src / drivers / bus / isapnp.c
diff --git a/qemu/roms/ipxe/src/drivers/bus/isapnp.c b/qemu/roms/ipxe/src/drivers/bus/isapnp.c
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+/**************************************************************************
+*
+*    isapnp.c -- Etherboot isapnp support for the 3Com 3c515
+*    Written 2002-2003 by Timothy Legge <tlegge@rogers.com>
+*
+*    This program is free software; you can redistribute it and/or modify
+*    it under the terms of the GNU General Public License as published by
+*    the Free Software Foundation; either version 2 of the License, or
+*    (at your option) any later version.
+*
+*    This program is distributed in the hope that it will be useful,
+*    but WITHOUT ANY WARRANTY; without even the implied warranty of
+*    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+*    GNU General Public License for more details.
+*
+*    You should have received a copy of the GNU General Public License
+*    along with this program; if not, write to the Free Software
+*    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+*    02110-1301, USA.
+*
+*    Portions of this code:
+*      Copyright (C) 2001  P.J.H.Fox (fox@roestock.demon.co.uk)
+*
+*
+*    REVISION HISTORY:
+*    ================
+*    Version 0.1 April 26, 2002 TJL
+*    Version 0.2 01/08/2003    TJL Moved outside the 3c515.c driver file
+*    Version 0.3 Sept 23, 2003 timlegge Change delay to currticks
+*              
+*
+*    Generalised into an ISAPnP bus that can be used by more than just
+*    the 3c515 by Michael Brown <mbrown@fensystems.co.uk>
+*
+***************************************************************************/
+
+/** @file
+ *
+ * ISAPnP bus support
+ *
+ * Etherboot orignally gained ISAPnP support in a very limited way for
+ * the 3c515 NIC.  The current implementation is almost a complete
+ * rewrite based on the ISAPnP specification, with passing reference
+ * to the Linux ISAPnP code.
+ *
+ * There can be only one ISAPnP bus in a system.  Once the read port
+ * is known and all cards have been allocated CSNs, there's nothing to
+ * be gained by re-scanning for cards.
+ *
+ * External code (e.g. the ISAPnP ROM prefix) may already know the
+ * read port address, in which case it can store it in
+ * #isapnp_read_port.  Note that setting the read port address in this
+ * way will prevent further isolation from taking place; you should
+ * set the read port address only if you know that devices have
+ * already been allocated CSNs.
+ *
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER );
+
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdio.h>
+#include <errno.h>
+#include <ipxe/io.h>
+#include <unistd.h>
+#include <ipxe/isapnp.h>
+
+/**
+ * ISAPnP Read Port address.
+ *
+ * ROM prefix may be able to set this address, which is why this is
+ * non-static.
+ */
+uint16_t isapnp_read_port;
+
+static void isapnpbus_remove ( struct root_device *rootdev );
+
+/*
+ * ISAPnP utility functions
+ *
+ */
+
+#define ISAPNP_CARD_ID_FMT "ID %04x:%04x (\"%s\") serial %x"
+#define ISAPNP_CARD_ID_DATA(identifier)                                          \
+       (identifier)->vendor_id, (identifier)->prod_id,                   \
+       isa_id_string ( (identifier)->vendor_id, (identifier)->prod_id ), \
+       (identifier)->serial
+#define ISAPNP_DEV_ID_FMT "ID %04x:%04x (\"%s\")"
+#define ISAPNP_DEV_ID_DATA(isapnp)                                       \
+       (isapnp)->vendor_id, (isapnp)->prod_id,                           \
+       isa_id_string ( (isapnp)->vendor_id, (isapnp)->prod_id )
+
+static inline void isapnp_write_address ( unsigned int address ) {
+       outb ( address, ISAPNP_ADDRESS );
+}
+
+static inline void isapnp_write_data ( unsigned int data ) {
+       outb ( data, ISAPNP_WRITE_DATA );
+}
+
+static inline unsigned int isapnp_read_data ( void ) {
+       return inb ( isapnp_read_port );
+}
+
+static inline void isapnp_write_byte ( unsigned int address,
+                                      unsigned int value ) {
+       isapnp_write_address ( address );
+       isapnp_write_data ( value );
+}
+
+static inline unsigned int isapnp_read_byte ( unsigned int address ) {
+       isapnp_write_address ( address );
+       return isapnp_read_data ();
+}
+
+static inline unsigned int isapnp_read_word ( unsigned int address ) {
+       /* Yes, they're in big-endian order */
+       return ( ( isapnp_read_byte ( address ) << 8 )
+                | isapnp_read_byte ( address + 1 ) );
+}
+
+/** Inform cards of a new read port address */
+static inline void isapnp_set_read_port ( void ) {
+       isapnp_write_byte ( ISAPNP_READPORT, ( isapnp_read_port >> 2 ) );
+}
+
+/**
+ * Enter the Isolation state.
+ *
+ * Only cards currently in the Sleep state will respond to this
+ * command.
+ */
+static inline void isapnp_serialisolation ( void ) {
+       isapnp_write_address ( ISAPNP_SERIALISOLATION );
+}
+
+/**
+ * Enter the Wait for Key state.
+ *
+ * All cards will respond to this command, regardless of their current
+ * state.
+ */
+static inline void isapnp_wait_for_key ( void ) {
+       isapnp_write_byte ( ISAPNP_CONFIGCONTROL, ISAPNP_CONFIG_WAIT_FOR_KEY );
+}
+
+/**
+ * Reset (i.e. remove) Card Select Number.
+ *
+ * Only cards currently in the Sleep state will respond to this
+ * command.
+ */
+static inline void isapnp_reset_csn ( void ) {
+       isapnp_write_byte ( ISAPNP_CONFIGCONTROL, ISAPNP_CONFIG_RESET_CSN );
+}
+
+/**
+ * Place a specified card into the Config state.
+ *
+ * @v csn              Card Select Number
+ * @ret None           -
+ * @err None           -
+ *
+ * Only cards currently in the Sleep, Isolation, or Config states will
+ * respond to this command.  The card that has the specified CSN will
+ * enter the Config state, all other cards will enter the Sleep state.
+ */
+static inline void isapnp_wake ( uint8_t csn ) {
+       isapnp_write_byte ( ISAPNP_WAKE, csn );
+}
+
+static inline unsigned int isapnp_read_resourcedata ( void ) {
+       return isapnp_read_byte ( ISAPNP_RESOURCEDATA );
+}
+
+static inline unsigned int isapnp_read_status ( void ) {
+       return isapnp_read_byte ( ISAPNP_STATUS );
+}
+
+/**
+ * Assign a Card Select Number to a card, and enter the Config state.
+ *
+ * @v csn              Card Select Number
+ *
+ * Only cards in the Isolation state will respond to this command.
+ * The isolation protocol is designed so that only one card will
+ * remain in the Isolation state by the time the isolation protocol
+ * completes.
+ */
+static inline void isapnp_write_csn ( unsigned int csn ) {
+       isapnp_write_byte ( ISAPNP_CARDSELECTNUMBER, csn );
+}
+
+static inline void isapnp_logicaldevice ( unsigned int logdev ) {
+       isapnp_write_byte ( ISAPNP_LOGICALDEVICENUMBER, logdev );
+}
+
+static inline void isapnp_activate ( unsigned int logdev ) {
+       isapnp_logicaldevice ( logdev );
+       isapnp_write_byte ( ISAPNP_ACTIVATE, 1 );
+}
+
+static inline void isapnp_deactivate ( unsigned int logdev ) {
+       isapnp_logicaldevice ( logdev );
+       isapnp_write_byte ( ISAPNP_ACTIVATE, 0 );
+}
+
+static inline unsigned int isapnp_read_iobase ( unsigned int index ) {
+       return isapnp_read_word ( ISAPNP_IOBASE ( index ) );
+}
+
+static inline unsigned int isapnp_read_irqno ( unsigned int index ) {
+       return isapnp_read_byte ( ISAPNP_IRQNO ( index ) );
+}
+
+static void isapnp_delay ( void ) {
+       udelay ( 1000 );
+}
+
+/**
+ * Linear feedback shift register.
+ *
+ * @v lfsr             Current value of the LFSR
+ * @v input_bit                Current input bit to the LFSR
+ * @ret lfsr           Next value of the LFSR
+ *
+ * This routine implements the linear feedback shift register as
+ * described in Appendix B of the PnP ISA spec.  The hardware
+ * implementation uses eight D-type latches and two XOR gates.  I
+ * think this is probably the smallest possible implementation in
+ * software.  Six instructions when input_bit is a constant 0 (for
+ * isapnp_send_key).  :)
+ */
+static inline unsigned int isapnp_lfsr_next ( unsigned int lfsr,
+                                             unsigned int input_bit ) {
+       register uint8_t lfsr_next;
+
+       lfsr_next = lfsr >> 1;
+       lfsr_next |= ( ( ( lfsr ^ lfsr_next ) ^ input_bit ) ) << 7;
+       return lfsr_next;
+}
+
+/**
+ * Send the ISAPnP initiation key.
+ *
+ * Sending the key causes all ISAPnP cards that are currently in the
+ * Wait for Key state to transition into the Sleep state.
+ */
+static void isapnp_send_key ( void ) {
+       unsigned int i;
+       unsigned int lfsr;
+
+       isapnp_delay();
+       isapnp_write_address ( 0x00 );
+       isapnp_write_address ( 0x00 );
+
+       lfsr = ISAPNP_LFSR_SEED;
+       for ( i = 0 ; i < 32 ; i++ ) {
+               isapnp_write_address ( lfsr );
+               lfsr = isapnp_lfsr_next ( lfsr, 0 );
+       }
+}
+
+/**
+ * Compute ISAPnP identifier checksum
+ *
+ * @v identifier       ISAPnP identifier
+ * @ret checksum       Expected checksum value
+ */
+static unsigned int isapnp_checksum ( struct isapnp_identifier *identifier ) {
+       unsigned int i, j;
+       unsigned int lfsr;
+       unsigned int byte;
+
+       lfsr = ISAPNP_LFSR_SEED;
+       for ( i = 0 ; i < 8 ; i++ ) {
+               byte = * ( ( ( uint8_t * ) identifier ) + i );
+               for ( j = 0 ; j < 8 ; j++ ) {
+                       lfsr = isapnp_lfsr_next ( lfsr, byte );
+                       byte >>= 1;
+               }
+       }
+       return lfsr;
+}
+
+/*
+ * Read a byte of resource data from the current location
+ *
+ * @ret byte           Byte of resource data
+ */
+static inline unsigned int isapnp_peek_byte ( void ) {
+       unsigned int i;
+
+       /* Wait for data to be ready */
+       for ( i = 0 ; i < 20 ; i++ ) {
+               if ( isapnp_read_status() & 0x01 ) {
+                       /* Byte ready - read it */
+                       return isapnp_read_resourcedata();
+               }
+               isapnp_delay();
+       }
+       /* Data never became ready - return 0xff */
+       return 0xff;
+}
+
+/**
+ * Read resource data.
+ *
+ * @v buf              Buffer in which to store data, or NULL
+ * @v bytes            Number of bytes to read
+ *
+ * Resource data is read from the current location.  If #buf is NULL,
+ * the data is discarded.
+ */
+static void isapnp_peek ( void *buf, size_t len ) {
+       unsigned int i;
+       unsigned int byte;
+
+       for ( i = 0 ; i < len ; i++) {
+               byte = isapnp_peek_byte();
+               if ( buf )
+                       * ( ( uint8_t * ) buf + i ) = byte;
+       }
+}
+
+/**
+ * Find a tag within the resource data.
+ *
+ * @v wanted_tag       The tag that we're looking for
+ * @v buf              Buffer in which to store the tag's contents
+ * @v len              Length of buffer
+ * @ret rc             Return status code
+ *
+ * Scan through the resource data until we find a particular tag, and
+ * read its contents into a buffer.
+ */
+static int isapnp_find_tag ( unsigned int wanted_tag, void *buf, size_t len ) {
+       unsigned int tag;
+       unsigned int tag_len;
+
+       DBG2 ( "ISAPnP read tag" );
+       do {
+               tag = isapnp_peek_byte();
+               if ( ISAPNP_IS_SMALL_TAG ( tag ) ) {
+                       tag_len = ISAPNP_SMALL_TAG_LEN ( tag );
+                       tag = ISAPNP_SMALL_TAG_NAME ( tag );
+               } else {
+                       tag_len = ( isapnp_peek_byte() +
+                                   ( isapnp_peek_byte() << 8 ) );
+                       tag = ISAPNP_LARGE_TAG_NAME ( tag );
+               }
+               DBG2 ( " %02x (%02x)", tag, tag_len );
+               if ( tag == wanted_tag ) {
+                       if ( len > tag_len )
+                               len = tag_len;
+                       isapnp_peek ( buf, len );
+                       DBG2 ( "\n" );
+                       return 0;
+               } else {
+                       isapnp_peek ( NULL, tag_len );
+               }
+       } while ( tag != ISAPNP_TAG_END );
+       DBG2 ( "\n" );
+       return -ENOENT;
+}
+
+/**
+ * Find specified Logical Device ID tag
+ *
+ * @v logdev           Logical device ID
+ * @v logdevid         Logical device ID structure to fill in
+ * @ret rc             Return status code
+ */
+static int isapnp_find_logdevid ( unsigned int logdev,
+                                 struct isapnp_logdevid *logdevid ) {
+       unsigned int i;
+       int rc;
+
+       for ( i = 0 ; i <= logdev ; i++ ) {
+               if ( ( rc = isapnp_find_tag ( ISAPNP_TAG_LOGDEVID, logdevid,
+                                             sizeof ( *logdevid ) ) ) != 0 )
+                       return rc;
+       }
+       return 0;
+}
+
+/**
+ * Try isolating ISAPnP cards at the current read port.
+ *
+ * @ret \>0            Number of ISAPnP cards found
+ * @ret 0              There are no ISAPnP cards in the system
+ * @ret \<0            A conflict was detected; try a new read port
+ * @err None           -
+ *
+ * The state diagram on page 18 (PDF page 24) of the PnP ISA spec
+ * gives the best overview of what happens here.
+ */
+static int isapnp_try_isolate ( void ) {
+       struct isapnp_identifier identifier;
+       unsigned int i, j;
+       unsigned int seen_55aa, seen_life;
+       unsigned int csn = 0;
+       unsigned int data;
+       unsigned int byte;
+
+       DBG ( "ISAPnP attempting isolation at read port %04x\n",
+             isapnp_read_port );
+
+       /* Place all cards into the Sleep state, whatever state
+        * they're currently in.
+        */
+       isapnp_wait_for_key();
+       isapnp_send_key();
+
+       /* Reset all assigned CSNs */
+       isapnp_reset_csn();
+       isapnp_delay();
+       isapnp_delay();
+       
+       /* Place all cards into the Isolation state */
+       isapnp_wait_for_key ();
+       isapnp_send_key();
+       isapnp_wake ( 0x00 );
+       
+       /* Set the read port */
+       isapnp_set_read_port();
+       isapnp_delay();
+
+       while ( 1 ) {
+
+               /* All cards that do not have assigned CSNs are
+                * currently in the Isolation state, each time we go
+                * through this loop.
+                */
+
+               /* Initiate serial isolation */
+               isapnp_serialisolation();
+               isapnp_delay();
+
+               /* Read identifier serially via the ISAPnP read port. */
+               memset ( &identifier, 0, sizeof ( identifier ) );
+               seen_55aa = seen_life = 0;
+               for ( i = 0 ; i < 9 ; i++ ) {
+                       byte = 0;
+                       for ( j = 0 ; j < 8 ; j++ ) {
+                               data = isapnp_read_data();
+                               isapnp_delay();
+                               data = ( ( data << 8 ) | isapnp_read_data() );
+                               isapnp_delay();
+                               byte >>= 1;
+                               if (  data != 0xffff ) {
+                                       seen_life++;
+                                       if ( data == 0x55aa ) {
+                                               byte |= 0x80;
+                                               seen_55aa++;
+                                       }
+                               }
+                       }
+                       *( ( ( uint8_t * ) &identifier ) + i ) = byte;
+               }
+
+               /* If we didn't see any 55aa patterns, stop here */
+               if ( ! seen_55aa ) {
+                       if ( csn ) {
+                               DBG ( "ISAPnP found no more cards\n" );
+                       } else {
+                               if ( seen_life ) {
+                                       DBG ( "ISAPnP saw life but no cards, "
+                                             "trying new read port\n" );
+                                       csn = -1;
+                               } else {
+                                       DBG ( "ISAPnP saw no signs of life, "
+                                             "abandoning isolation\n" );
+                               }
+                       }
+                       break;
+               }
+
+               /* If the checksum was invalid stop here */
+               if ( identifier.checksum != isapnp_checksum ( &identifier) ) {
+                       DBG ( "ISAPnP found malformed card "
+                             ISAPNP_CARD_ID_FMT "\n  with checksum %02x "
+                             "(should be %02x), trying new read port\n",
+                             ISAPNP_CARD_ID_DATA ( &identifier ),
+                             identifier.checksum,
+                             isapnp_checksum ( &identifier) );
+                       csn = -1;
+                       break;
+               }
+
+               /* Give the device a CSN */
+               csn++;
+               DBG ( "ISAPnP found card " ISAPNP_CARD_ID_FMT
+                     ", assigning CSN %02x\n",
+                     ISAPNP_CARD_ID_DATA ( &identifier ), csn );
+               
+               isapnp_write_csn ( csn );
+               isapnp_delay();
+
+               /* Send this card back to Sleep and force all cards
+                * without a CSN into Isolation state
+                */
+               isapnp_wake ( 0x00 );
+               isapnp_delay();
+       }
+
+       /* Place all cards in Wait for Key state */
+       isapnp_wait_for_key();
+
+       /* Return number of cards found */
+       if ( csn > 0 ) {
+               DBG ( "ISAPnP found %d cards at read port %04x\n",
+                     csn, isapnp_read_port );
+       }
+       return csn;
+}
+
+/**
+ * Find a valid read port and isolate all ISAPnP cards.
+ *
+ */
+static void isapnp_isolate ( void ) {
+       for ( isapnp_read_port = ISAPNP_READ_PORT_START ;
+             isapnp_read_port <= ISAPNP_READ_PORT_MAX ;
+             isapnp_read_port += ISAPNP_READ_PORT_STEP ) {
+               /* Avoid problematic locations such as the NE2000
+                * probe space
+                */
+               if ( ( isapnp_read_port >= 0x280 ) &&
+                    ( isapnp_read_port <= 0x380 ) )
+                       continue;
+               
+               /* If we detect any ISAPnP cards at this location, stop */
+               if ( isapnp_try_isolate() >= 0 )
+                       return;
+       }
+}
+
+/**
+ * Activate or deactivate an ISAPnP device.
+ *
+ * @v isapnp           ISAPnP device
+ * @v activation       True to enable, False to disable the device
+ * @ret None           -
+ * @err None           -
+ *
+ * This routine simply activates the device in its current
+ * configuration, or deactivates the device.  It does not attempt any
+ * kind of resource arbitration.
+ *
+ */
+void isapnp_device_activation ( struct isapnp_device *isapnp,
+                               int activation ) {
+       /* Wake the card and select the logical device */
+       isapnp_wait_for_key ();
+       isapnp_send_key ();
+       isapnp_wake ( isapnp->csn );
+       isapnp_logicaldevice ( isapnp->logdev );
+
+       /* Activate/deactivate the logical device */
+       isapnp_activate ( activation );
+       isapnp_delay();
+
+       /* Return all cards to Wait for Key state */
+       isapnp_wait_for_key ();
+
+       DBG ( "ISAPnP %s device %02x:%02x\n",
+             ( activation ? "activated" : "deactivated" ),
+             isapnp->csn, isapnp->logdev );
+}
+
+/**
+ * Probe an ISAPnP device
+ *
+ * @v isapnp           ISAPnP device
+ * @ret rc             Return status code
+ *
+ * Searches for a driver for the ISAPnP device.  If a driver is found,
+ * its probe() routine is called.
+ */
+static int isapnp_probe ( struct isapnp_device *isapnp ) {
+       struct isapnp_driver *driver;
+       struct isapnp_device_id *id;
+       unsigned int i;
+       int rc;
+
+       DBG ( "Adding ISAPnP device %02x:%02x (%04x:%04x (\"%s\") "
+             "io %x irq %d)\n", isapnp->csn, isapnp->logdev,
+             isapnp->vendor_id, isapnp->prod_id,
+             isa_id_string ( isapnp->vendor_id, isapnp->prod_id ),
+             isapnp->ioaddr, isapnp->irqno );
+
+       for_each_table_entry ( driver, ISAPNP_DRIVERS ) {
+               for ( i = 0 ; i < driver->id_count ; i++ ) {
+                       id = &driver->ids[i];
+                       if ( id->vendor_id != isapnp->vendor_id )
+                               continue;
+                       if ( ISA_PROD_ID ( id->prod_id ) !=
+                            ISA_PROD_ID ( isapnp->prod_id ) )
+                               continue;
+                       isapnp->driver = driver;
+                       isapnp->dev.driver_name = id->name;
+                       DBG ( "...using driver %s\n", isapnp->dev.driver_name );
+                       if ( ( rc = driver->probe ( isapnp, id ) ) != 0 ) {
+                               DBG ( "......probe failed\n" );
+                               continue;
+                       }
+                       return 0;
+               }
+       }
+
+       DBG ( "...no driver found\n" );
+       return -ENOTTY;
+}
+
+/**
+ * Remove an ISAPnP device
+ *
+ * @v isapnp           ISAPnP device
+ */
+static void isapnp_remove ( struct isapnp_device *isapnp ) {
+       isapnp->driver->remove ( isapnp );
+       DBG ( "Removed ISAPnP device %02x:%02x\n",
+             isapnp->csn, isapnp->logdev );
+}
+
+/**
+ * Probe ISAPnP root bus
+ *
+ * @v rootdev          ISAPnP bus root device
+ *
+ * Scans the ISAPnP bus for devices and registers all devices it can
+ * find.
+ */
+static int isapnpbus_probe ( struct root_device *rootdev ) {
+       struct isapnp_device *isapnp = NULL;
+       struct isapnp_identifier identifier;
+       struct isapnp_logdevid logdevid;
+       unsigned int csn;
+       unsigned int logdev;
+       int rc;
+
+       /* Perform isolation if it hasn't yet been done */
+       if ( ! isapnp_read_port )
+               isapnp_isolate();
+
+       for ( csn = 1 ; csn <= 0xff ; csn++ ) {
+               for ( logdev = 0 ; logdev <= 0xff ; logdev++ ) {
+
+                       /* Allocate struct isapnp_device */
+                       if ( ! isapnp )
+                               isapnp = malloc ( sizeof ( *isapnp ) );
+                       if ( ! isapnp ) {
+                               rc = -ENOMEM;
+                               goto err;
+                       }
+                       memset ( isapnp, 0, sizeof ( *isapnp ) );
+                       isapnp->csn = csn;
+                       isapnp->logdev = logdev;
+
+                       /* Wake the card */
+                       isapnp_wait_for_key();
+                       isapnp_send_key();
+                       isapnp_wake ( csn );
+
+                       /* Read the card identifier */
+                       isapnp_peek ( &identifier, sizeof ( identifier ) );
+                       
+                       /* No card with this CSN; stop here */
+                       if ( identifier.vendor_id & 0x80 )
+                               goto done;
+
+                       /* Find the Logical Device ID tag */
+                       if ( ( rc = isapnp_find_logdevid ( logdev,
+                                                          &logdevid ) ) != 0){
+                               /* No more logical devices; go to next CSN */
+                               break;
+                       }
+                       
+                       /* Select the logical device */
+                       isapnp_logicaldevice ( logdev );
+
+                       /* Populate struct isapnp_device */
+                       isapnp->vendor_id = logdevid.vendor_id;
+                       isapnp->prod_id = logdevid.prod_id;
+                       isapnp->ioaddr = isapnp_read_iobase ( 0 );
+                       isapnp->irqno = isapnp_read_irqno ( 0 );
+
+                       /* Return all cards to Wait for Key state */
+                       isapnp_wait_for_key();
+
+                       /* Add to device hierarchy */
+                       snprintf ( isapnp->dev.name,
+                                  sizeof ( isapnp->dev.name ),
+                                  "ISAPnP%02x:%02x", csn, logdev );
+                       isapnp->dev.desc.bus_type = BUS_TYPE_ISAPNP;
+                       isapnp->dev.desc.vendor = isapnp->vendor_id;
+                       isapnp->dev.desc.device = isapnp->prod_id;
+                       isapnp->dev.desc.ioaddr = isapnp->ioaddr;
+                       isapnp->dev.desc.irq = isapnp->irqno;
+                       isapnp->dev.parent = &rootdev->dev;
+                       list_add ( &isapnp->dev.siblings,
+                                  &rootdev->dev.children );
+                       INIT_LIST_HEAD ( &isapnp->dev.children );
+                       
+                       /* Look for a driver */
+                       if ( isapnp_probe ( isapnp ) == 0 ) {
+                               /* isapnpdev registered, we can drop our ref */
+                               isapnp = NULL;
+                       } else {
+                               /* Not registered; re-use struct */
+                               list_del ( &isapnp->dev.siblings );
+                       }
+               }
+       }
+
+ done:
+       free ( isapnp );
+       return 0;
+
+ err:
+       free ( isapnp );
+       isapnpbus_remove ( rootdev );
+       return rc;
+}
+
+/**
+ * Remove ISAPnP root bus
+ *
+ * @v rootdev          ISAPnP bus root device
+ */
+static void isapnpbus_remove ( struct root_device *rootdev ) {
+       struct isapnp_device *isapnp;
+       struct isapnp_device *tmp;
+
+       list_for_each_entry_safe ( isapnp, tmp, &rootdev->dev.children,
+                                  dev.siblings ) {
+               isapnp_remove ( isapnp );
+               list_del ( &isapnp->dev.siblings );
+               free ( isapnp );
+       }
+}
+
+/** ISAPnP bus root device driver */
+static struct root_driver isapnp_root_driver = {
+       .probe = isapnpbus_probe,
+       .remove = isapnpbus_remove,
+};
+
+/** ISAPnP bus root device */
+struct root_device isapnp_root_device __root_device = {
+       .dev = { .name = "ISAPnP" },
+       .driver = &isapnp_root_driver,
+};