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 paral

lel 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: COMPAT

IBLE, 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 oper

ating 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: detec

tion and initialisation 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
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 con

figuration.
You may disable chipset specific detection by using the

above flags.

BSD March 5, 1998

BSD