NAME

       ppc — Parallel Port Chipset driver

SYNOPSIS

       device ppc

       In /boot/device.hints:
       hint.ppc.0.at="isa"
       hint.ppc.0.irq="7"

       For one or more PPBUS busses:
       device ppbus

DESCRIPTION

       The ppc driver provides low level support to various parallel port chipsets for the ppbus(4) system.

       During  the  probe  phase,  ppc  detects parallel port chipsets and initializes private data according to
       their operating mode: COMPATIBLE, NIBBLE, PS/2, EPP, ECP and other mixed modes.  If a mode is provided at
       startup through the flags variable of the boot interface, the operating mode of  the  chipset  is  forced
       according to flags and the hardware supported modes.

       During  the  attach  phase,  ppc  allocates  a ppbus structure, initializes it and calls the ppbus attach
       function.

   Supported flags
             bits 0-3: chipset forced mode(s)

             PPB_COMPATIBLE  0x0     /* Centronics compatible mode */
             PPB_NIBBLE      0x1     /* reverse 4 bit mode */
             PPB_PS2         0x2     /* PS/2 byte mode */
             PPB_EPP         0x4     /* EPP mode, 32 bit */
             PPB_ECP         0x8     /* ECP mode */

             And any mixed values.

             bit 4: EPP protocol (0 EPP 1.9, 1 EPP 1.7)

             bit 5: activate IRQ (1 IRQ disabled, 0 IRQ enabled)

             bit 6: disable chipset specific detection

             bit 7: disable FIFO detection

   Supported chipsets
       Some parallel port chipsets are explicitly supported: detection and initialisation code has been  written
       according to their datasheets.

             •   SMC FDC37C665GT and FDC37C666GT chipsets

             •   Natsemi PC873xx-family (PC87332 and PC87306)

             •   Winbond W83877xx-family (W83877F and W83877AF)

             •   SMC-like chipsets with mixed modes (see ppbus(4))

   Adding support to a new chipset
       You may want to add support for the newest chipset your motherboard was sold with.  For the ISA bus, just
       retrieve  the specs of the chipset and write the corresponding ppc_mychipset_detect() function.  Then add
       an entry to the general purpose ppc_detect() function.

       Your ppc_mychipset_detect() function should ensure that if the mode field of the flags boot  variable  is
       not  null,  then  the  operating  mode  is  forced  to  the given mode and no other mode is available and
       ppb->ppb_avm field contains the available modes of the chipset.

SEE ALSO

       ppbus(4), ppi(4), device.hints(5)

HISTORY

       The ppc manual page first appeared in FreeBSD 3.0.

AUTHORS

       This manual page was written by Nicolas Souchu.

BUGS

       The chipset detection process may corrupt your chipset configuration.  You may disable  chipset  specific
       detection by using the above flags.

Debian                                            March 5, 1998                                           PPC(4)