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PPC(4)			    Kernel Interfaces Manual			PPC(4)

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 initial-
       izes private data according to their operating mode:  COMPATIBLE,  NIB-
       BLE,  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  sup-
       ported 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.

FreeBSD	14.3			 March 5, 1998				PPC(4)

Want to link to this manual page? Use this URL:
<https://man.freebsd.org/cgi/man.cgi?query=ppc&sektion=4&manpath=FreeBSD+14.3-RELEASE+and+Ports>

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