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PPC(4)			 BSD Kernel Interfaces Manual			PPC(4)

     ppc -- Parallel Port Chipset driver

     device ppc

     In	/boot/device.hints:"isa"

     For one or	more PPBUS busses:
     device ppbus

     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, 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

     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 ini-
     tialisation code has been written according to their datasheets.

	   o   SMC FDC37C665GT and FDC37C666GT chipsets

	   o   Natsemi PC873xx-family (PC87332 and PC87306)

	   o   Winbond W83877xx-family (W83877F	and W83877AF)

	   o   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 en-
     try 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.

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

     The ppc manual page first appeared	in FreeBSD 3.0.

     This manual page was written by Nicolas Souchu.

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

BSD				 March 5, 1998				   BSD


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