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committed ca5dc2d1178/* * Generic parallel printer driver * * Copyright (C) 1992 by Jim Weigand and Linus Torvalds * Copyright (C) 1992,1993 by Michael K. Johnson * - Thanks much to Gunter Windau for pointing out to me where the error * checking ought to be. * Copyright (C) 1993 by Nigel Gamble (added interrupt code) * Copyright (C) 1994 by Alan Cox (Modularised it) * LPCAREFUL, LPABORT, LPGETSTATUS added by Chris Metcalf, metcalf@lcs.mit.edu * Statistics and support for slow printers by Rob Janssen, rob@knoware.nl * "lp=" command line parameters added by Grant Guenther, grant@torque.net * lp_read (Status readback) support added by Carsten Gross, * carsten@sol.wohnheim.uni-ulm.de * Support for parport by Philip Blundell <philb@gnu.org> * Parport sharing hacking by Andrea Arcangeli * Fixed kernel_(to/from)_user memory copy to check for errors * by Riccardo Facchetti <fizban@tin.it> * 22-JAN-1998 Added support for devfs Richard Gooch <rgooch@atnf.csiro.au> * Redesigned interrupt handling for handle printers with buggy handshake * by Andrea Arcangeli, 11 May 1998 * Full efficient handling of printer with buggy irq handshake (now I have * understood the meaning of the strange handshake). This is done sending new * characters if the interrupt is just happened, even if the printer say to * be still BUSY. This is needed at least with Epson Stylus Color. To enable * the new TRUST_IRQ mode read the `LP OPTIMIZATION' section below... * Fixed the irq on the rising edge of the strobe case. * Obsoleted the CAREFUL flag since a printer that doesn' t work with * CAREFUL will block a bit after in lp_check_status(). * Andrea Arcangeli, 15 Oct 1998 * Obsoleted and removed all the lowlevel stuff implemented in the last * month to use the IEEE1284 functions (that handle the _new_ compatibilty * mode fine). *//* This driver should, in theory, work with any parallel port that has an * appropriate low-level driver; all I/O is done through the parport * abstraction layer. * * If this driver is built into the kernel, you can configure it using the * kernel command-line. For example: * * lp=parport1,none,parport2 (bind lp0 to parport1, disable lp1 and * bind lp2 to parport2) * * lp=auto (assign lp devices to all ports that * have printers attached, as determined * by the IEEE-1284 autoprobe) * * lp=reset (reset the printer during * initialisation) * * lp=off (disable the printer driver entirely) * * If the driver is loaded as a module, similar functionality is available * using module parameters. The equivalent of the above commands would be: * * # insmod lp.o parport=1,none,2 * * # insmod lp.o parport=auto * * # insmod lp.o reset=1 *//* COMPATIBILITY WITH OLD KERNELS * * Under Linux 2.0 and previous versions, lp devices were bound to ports at * particular I/O addresses, as follows: * * lp0 0x3bc * lp1 0x378 * lp2 0x278 * * The new driver, by default, binds lp devices to parport devices as it * finds them. This means that if you only have one port, it will be bound * to lp0 regardless of its I/O address. If you need the old behaviour, you * can force it using the parameters described above. *//* * The new interrupt handling code take care of the buggy handshake * of some HP and Epson printer: * ___ * ACK _______________ ___________ * |__| * ____ * BUSY _________ _______ * |____________| * * I discovered this using the printer scanner that you can find at: * * ftp://e-mind.com/pub/linux/pscan/