| /* Line printer stuff mostly follows the original Centronics printers. See |
| IEEE Std.1284-1994 Standard Signaling Method for a Bi-directional Parallel |
| Peripheral Interface for Personal Computers for 5 modes of data transfer. */ |
| |
| /* Parallel port registers: data (0x3bc, 0x378, 0x278), status=data+1, control=data+2 */ |
| |
| /* Parallel port status register (read only): |
| bit 7: NBSY (1: ready, 0: busy or error or off-line) |
| bit 6: NACK (if NBSY=1, then 1; if NBSY=0 then 1: sending data, 0: ready with data) |
| bit 5: PAP (1: out-of-paper) |
| bit 4: OFON (1: on-line) |
| bit 3: NFEH (1: OK, 0: printer error) |
| bits 2-0: 07 |
| |
| On out-of-paper: PAP=1, OFON=0, NFEH=1. |
| |
| "When reading the busy status, read twice in a row and use the value |
| obtained from the second read. This improves the reliability on some |
| parallel ports when the busy line may not be connected and is floating." |
| "On some Okidata printers when the busy signal switches from high to low, |
| the printer sends a 50 ns glitch on the paper out signal line. Before |
| declaring a paper out condition, check the status again." |
| (The Undocumented PC, F. van Gilluwe, p. 711) |
| */ |
| |
| /* Parallel port control register (read/write): |
| bit 4: IRQ (1: we want an interrupt when NACK goes from 1 to 0) |
| bit 3: DSL (1: activate printer) |
| bit 2: NINI (0: initialise printer) |
| bit 1: ALF (1: printer performs automatic linefeed after each line) |
| bit 0: STR (0->1: generate a Strobe pulse: transport data to printer) |
| */ |
| |
| /* Parallel port timing: |
| 1. wait for NBSY=1 |
| 2. outb(data byte, data port) |
| 3. wait for at least 0.5us |
| 4. read control port, OR with STR=0x1, output to control port - purpose: |
| generate strobe pulse; this will make the busy line go high |
| 5. wait for at least 0.5us |
| 6. read control port, AND with !STR, output to control port |
| 7. wait for at least 0.5us |
| 8. in a loop: read status register until NACK bit is 0 or NBSY=1 |
| (the printer will keep NACK=0 for at least 0.5us, then NACK=NBSY=1). |
| */ |
| |
| |
| /* lp ioctls */ |
| #define LPCHAR 0x0601 /* specify the number of times we ask for the status |
| (waiting for ready) before giving up with a timeout |
| The duration may mainly depend on the timing of an inb. */ |
| #define LPTIME 0x0602 /* time to sleep after each timeout (in units of 0.01 sec) */ |
| #define LPABORT 0x0604 /* call with TRUE arg to abort on error, |
| FALSE to retry. Default is retry. */ |
| #define LPSETIRQ 0x0605 /* call with new IRQ number, |
| or 0 for polling (no IRQ) */ |
| #define LPGETIRQ 0x0606 /* get the current IRQ number */ |
| #define LPWAIT 0x0608 /* #of loops to wait before taking strobe high */ |
| #define LPCAREFUL 0x0609 /* call with TRUE arg to require out-of-paper, off- |
| line, and error indicators good on all writes, |
| FALSE to ignore them. Default is ignore. */ |
| #define LPABORTOPEN 0x060a /* call with TRUE arg to abort open() on error, |
| FALSE to ignore error. Default is ignore. */ |
| #define LPGETSTATUS 0x060b /* return LP_S(minor) */ |
| #define LPRESET 0x060c /* reset printer */ |
| #define LPGETFLAGS 0x060e /* get status flags */ |
| |
| #define LPSTRICT 0x060f /* enable/disable strict compliance (2.0.36) */ |
| /* Strict: wait until !READY before taking strobe low; |
| this may be bad for the Epson Stylus 800. |
| Not strict: wait a constant time as given by LPWAIT */ |
| #define LPTRUSTIRQ 0x060f /* set/unset the LP_TRUST_IRQ flag (2.1.131) */ |
| |
| /* |
| * bit defines for 8255 status port |
| * base + 1 |
| * accessed with LP_S(minor), which gets the byte... |
| */ |
| #define LP_PBUSY 0x80 /* inverted input, active high */ |
| #define LP_PACK 0x40 /* unchanged input, active low */ |
| #define LP_POUTPA 0x20 /* unchanged input, active high */ |
| #define LP_PSELECD 0x10 /* unchanged input, active high */ |
| #define LP_PERRORP 0x08 /* unchanged input, active low */ |
