diff options
Diffstat (limited to 'drivers/misc/parport_ieee1284.c')
| -rw-r--r-- | drivers/misc/parport_ieee1284.c | 83 |
1 files changed, 32 insertions, 51 deletions
diff --git a/drivers/misc/parport_ieee1284.c b/drivers/misc/parport_ieee1284.c index 6fad49911..23152fa41 100644 --- a/drivers/misc/parport_ieee1284.c +++ b/drivers/misc/parport_ieee1284.c @@ -1,4 +1,5 @@ -/* IEEE-1284 implementation for parport. +/* $Id: parport_ieee1284.c,v 1.4 1997/12/15 10:37:47 ralf Exp $ + * IEEE-1284 implementation for parport. * * Authors: Phil Blundell <Philip.Blundell@pobox.com> * Carsten Gross <carsten@sol.wohnheim.uni-ulm.de> @@ -6,83 +7,63 @@ */ #include <linux/tasks.h> - #include <linux/parport.h> #include <linux/delay.h> -#include <linux/errno.h> -#include <linux/interrupt.h> -#include <linux/ioport.h> #include <linux/kernel.h> -#include <linux/malloc.h> - -/* The following read functions are an implementation of a status readback - * and device id request confirming to IEEE1284-1994. - * - * These probably ought to go in some seperate file, so people like the SPARC - * don't have to pull them in. - */ /* Wait for Status line(s) to change in 35 ms - see IEEE1284-1994 page 24 to * 25 for this. After this time we can create a timeout because the - * peripheral doesn't conform to IEEE1284. We want to save CPU time: we are - * waiting a maximum time of 500 us busy (this is for speed). If there is + * peripheral doesn't conform to IEEE1284. We want to save CPU time: we are + * waiting a maximum time of 500 us busy (this is for speed). If there is * not the right answer in this time, we call schedule and other processes - * are able "to eat" the time up to 30ms. So the maximum load avarage can't - * get above 5% for a read even if the peripheral is really slow. (but your - * read gets very slow then - only about 10 characters per second. This - * should be tuneable). Thanks to Andreas who pointed me to this and ordered - * the documentation. + * are able to eat the time up to 40ms. */ int parport_wait_peripheral(struct parport *port, unsigned char mask, unsigned char result) { - int counter=0; + int counter; unsigned char status; - do { + for (counter = 0; counter < 20; counter++) { status = parport_read_status(port); + if ((status & mask) == result) + return 0; udelay(25); - counter++; if (need_resched) schedule(); - } while ( ((status & mask) != result) && (counter < 20) ); - if ( (counter == 20) && ((status & mask) != result) ) { - current->state=TASK_INTERRUPTIBLE; - current->timeout=jiffies+4; - schedule(); /* wait for 4 scheduler runs (40ms) */ - status = parport_read_status(port); - if ((status & mask) != result) return 1; /* timeout */ } - return 0; /* okay right response from device */ + current->state = TASK_INTERRUPTIBLE; + current->timeout = jiffies+4; + schedule(); /* wait for 40ms */ + status = parport_read_status(port); + return ((status & mask) == result)?0:1; } -/* Test if nibble mode for status readback is okay. Returns the value false - * if the printer doesn't support readback at all. If it supports readbacks - * and printer data is available the function returns 1, otherwise 2. The - * only valid values for "mode" are 0 and 4. 0 requests normal nibble mode, - * 4 is for "request device id using nibble mode". The request for the - * device id is best done in an ioctl (or at bootup time). There is no - * check for an invalid value, the only function using this call at the - * moment is lp_read and the ioctl LPGETDEVICEID both fixed calls from - * trusted kernel. +/* Test if the peripheral is IEEE 1284 compliant. + * return values are: + * 0 - handshake failed; peripheral is not compliant (or none present) + * 1 - handshake OK; IEEE1284 peripheral present but no data available + * 2 - handshake OK; IEEE1284 peripheral and data available */ int parport_ieee1284_nibble_mode_ok(struct parport *port, unsigned char mode) { parport_write_data(port, mode); - udelay(5); - parport_write_control(port, parport_read_control(port) & ~8); /* SelectIN low */ - parport_write_control(port, parport_read_control(port) | 2); /* AutoFeed high */ - if (parport_wait_peripheral(port, 0x78, 0x38)) { /* timeout? */ - parport_write_control(port, (parport_read_control(port) & ~2) | 8); - return 0; /* first stage of negotiation failed, - * no IEEE1284 compliant device on this port - */ + udelay(500); + /* nSelectIn high, nAutoFd low */ + parport_write_control(port, (parport_read_control(port) & ~8) | 2); + if (parport_wait_peripheral(port, 0x78, 0x38)) { + parport_write_control(port, + (parport_read_control(port) & ~2) | 8); + return 0; } - parport_write_control(port, parport_read_control(port) | 1); /* Strobe high */ + /* nStrobe low */ + parport_write_control(port, parport_read_control(port) | 1); udelay(5); /* Strobe wait */ - parport_write_control(port, parport_read_control(port) & ~1); /* Strobe low */ + /* nStrobe high */ + parport_write_control(port, parport_read_control(port) & ~1); udelay(5); - parport_write_control(port, parport_read_control(port) & ~2); /* AutoFeed low */ + /* nAutoFd low */ + parport_write_control(port, parport_read_control(port) & ~2); return (parport_wait_peripheral(port, 0x20, 0))?2:1; } |