printer.c

Go to the documentation of this file.

/* This file contains the printer driver. It is a fairly simple driver,
 * supporting only one printer.  Characters that are written to the driver
 * are written to the printer without any changes at all.
 *
 * Changes:
 *      May 07, 2004    fix: wait until printer is ready  (Jorrit N. Herder)
 *      May 06, 2004    printer driver moved to user-space  (Jorrit N. Herder) 
 *
 * The valid messages and their parameters are:
 *
 *   DEV_OPEN:  initializes the printer
 *   DEV_CLOSE: does nothing
 *   HARD_INT:  interrupt handler has finished current chunk of output
 *   DEV_WRITE: a process wants to write on a terminal
 *   CANCEL:    terminate a previous incomplete system call immediately
 *
 *    m_type      TTY_LINE   IO_ENDPT    COUNT    ADDRESS
 * |-------------+---------+---------+---------+---------|
 * | DEV_OPEN    |         |         |         |         |
 * |-------------+---------+---------+---------+---------|
 * | DEV_CLOSE   |         | proc nr |         |         |
 * -------------------------------------------------------
 * | HARD_INT    |         |         |         |         |
 * |-------------+---------+---------+---------+---------|
 * | SYS_EVENT   |         |         |         |         |
 * |-------------+---------+---------+---------+---------|
 * | DEV_WRITE   |minor dev| proc nr |  count  | buf ptr |
 * |-------------+---------+---------+---------+---------|
 * | CANCEL      |minor dev| proc nr |         |         |
 * -------------------------------------------------------
 * 
 * Note: since only 1 printer is supported, minor dev is not used at present.
 */

#include "../drivers.h"

/* Control bits (in port_base + 2).  "+" means positive logic and "-" means
 * negative logic.  Most of the signals are negative logic on the pins but
 * many are converted to positive logic in the ports.  Some manuals are
 * misleading because they only document the pin logic.
 *
 *      +0x01   Pin 1   -Strobe
 *      +0x02   Pin 14  -Auto Feed
 *      -0x04   Pin 16  -Initialize Printer
 *      +0x08   Pin 17  -Select Printer
 *      +0x10   IRQ7 Enable
 *
 * Auto Feed and Select Printer are always enabled. Strobe is enabled briefly
 * when characters are output.  Initialize Printer is enabled briefly when
 * the task is started.  IRQ7 is enabled when the first character is output
 * and left enabled until output is completed (or later after certain
 * abnormal completions).
 */
#define ASSERT_STROBE   0x1D    /* strobe a character to the interface */
#define NEGATE_STROBE   0x1C    /* enable interrupt on interface */
#define PR_SELECT          0x0C /* select printer bit */
#define INIT_PRINTER    0x08    /* init printer bits */

/* Status bits (in port_base + 2).
 *
 *      -0x08   Pin 15  -Error
 *      +0x10   Pin 13  +Select Status
 *      +0x20   Pin 12  +Out of Paper
 *      -0x40   Pin 10  -Acknowledge
 *      -0x80   Pin 11  +Busy
 */
#define BUSY_STATUS     0x10    /* printer gives this status when busy */
#define NO_PAPER        0x20    /* status bit saying that paper is out */
#define NORMAL_STATUS   0x90    /* printer gives this status when idle */
#define ON_LINE         0x10    /* status bit saying that printer is online */
#define STATUS_MASK     0xB0    /* mask to filter out status bits */ 

#define MAX_ONLINE_RETRIES 120  /* about 60s: waits 0.5s after each retry */

/* Centronics interface timing that must be met by software (in microsec).
 *
 * Strobe length:       0.5u to 100u (not sure about the upper limit).
 * Data set up:         0.5u before strobe.
 * Data hold:           0.5u after strobe.
 * Init pulse length:   over 200u (not sure).
 *
 * The strobe length is about 50u with the code here and function calls for
 * sys_outb() - not much to spare.  The 0.5u minimums will not be violated 
 * with the sys_outb() messages exchanged.
 */

PRIVATE int caller;             /* process to tell when printing done (FS) */
PRIVATE int revive_pending;     /* set to true if revive is pending */
PRIVATE int revive_status;      /* revive status */
PRIVATE int done_status;        /* status of last output completion */
PRIVATE int oleft;              /* bytes of output left in obuf */
PRIVATE char obuf[128];         /* output buffer */
PRIVATE char *optr;             /* ptr to next char in obuf to print */
PRIVATE int orig_count;         /* original byte count */
PRIVATE int port_base;          /* I/O port for printer */
PRIVATE int proc_nr;            /* user requesting the printing */
PRIVATE int user_left;          /* bytes of output left in user buf */
PRIVATE vir_bytes user_vir;     /* address of remainder of user buf */
PRIVATE int writing;            /* nonzero while write is in progress */
PRIVATE int irq_hook_id;        /* id of irq hook at kernel */

extern int errno;               /* error number */

FORWARD _PROTOTYPE( void do_cancel, (message *m_ptr) );
FORWARD _PROTOTYPE( void output_done, (void) );
FORWARD _PROTOTYPE( void do_write, (message *m_ptr) );
FORWARD _PROTOTYPE( void do_status, (message *m_ptr) );
FORWARD _PROTOTYPE( void prepare_output, (void) );
FORWARD _PROTOTYPE( void do_initialize, (void) );
FORWARD _PROTOTYPE( void reply, (int code,int replyee,int proc,int status));
FORWARD _PROTOTYPE( void do_printer_output, (void) );
FORWARD _PROTOTYPE( void do_signal, (message *m_ptr) );


/*===========================================================================*
 *                              printer_task                                 *
 *===========================================================================*/
PUBLIC void main(void)
{
/* Main routine of the printer task. */
  message pr_mess;              /* buffer for all incoming messages */
  struct sigaction sa;
  int s;

  /* Install signal handlers. Ask PM to transform signal into message. */
  sa.sa_handler = SIG_MESS;
  sigemptyset(&sa.sa_mask);
  sa.sa_flags = 0;
  if (sigaction(SIGTERM,&sa,NULL)<0) panic("PRN","sigaction failed", errno);
  
  while (TRUE) {
        receive(ANY, &pr_mess);
        switch(pr_mess.m_type) {
            case DEV_OPEN:
                 do_initialize();               /* initialize */
                /* fall through */
            case DEV_CLOSE:
                reply(TASK_REPLY, pr_mess.m_source, pr_mess.IO_ENDPT, OK);
                break;
            case DEV_WRITE:     do_write(&pr_mess);     break;
            case DEV_STATUS:    do_status(&pr_mess);    break;
            case CANCEL:        do_cancel(&pr_mess);    break;
            case HARD_INT:      do_printer_output();    break;
            case SYS_SIG:       do_signal(&pr_mess);    break;
            case DEV_PING:      notify(pr_mess.m_source);       break;
            case PROC_EVENT:    break;
            default:
                reply(TASK_REPLY, pr_mess.m_source, pr_mess.IO_ENDPT, EINVAL);
        }
  }
}


/*===========================================================================*
 *                               do_signal                                   *
 *===========================================================================*/
PRIVATE void do_signal(m_ptr)
message *m_ptr;                                 /* signal message */
{
  int sig;
  sigset_t sigset = m_ptr->NOTIFY_ARG;
  
  /* Expect a SIGTERM signal when this server must shutdown. */
  if (sigismember(&sigset, SIGTERM)) {
        exit(0);
  } 
  /* Ignore all other signals. */
}

/*===========================================================================*
 *                              do_write                                     *
 *===========================================================================*/
PRIVATE void do_write(m_ptr)
register message *m_ptr;        /* pointer to the newly arrived message */
{
/* The printer is used by sending DEV_WRITE messages to it. Process one. */

    register int r = SUSPEND;
    int retries;
    unsigned long status;

    /* Reject command if last write is not yet finished, the count is not
     * positive, or the user address is bad.
     */
    if (writing)                        r = EIO;
    else if (m_ptr->COUNT <= 0)         r = EINVAL;

    /* Reply to FS, no matter what happened, possible SUSPEND caller. */
    reply(TASK_REPLY, m_ptr->m_source, m_ptr->IO_ENDPT, r);

    /* If no errors occurred, continue printing with SUSPENDED caller.
     * First wait until the printer is online to prevent stupid errors.
     */
    if (SUSPEND == r) {         
        caller = m_ptr->m_source;
        proc_nr = m_ptr->IO_ENDPT;
        user_left = m_ptr->COUNT;
        orig_count = m_ptr->COUNT;
        user_vir = (vir_bytes) m_ptr->ADDRESS;
        writing = TRUE;

        retries = MAX_ONLINE_RETRIES + 1;  
        while (--retries > 0) {
            sys_inb(port_base + 1, &status);
            if ((status & ON_LINE)) {           /* printer online! */
                prepare_output();
                do_printer_output();
                return;
            }
            tickdelay(30);              /* wait before retry */
        }
        /* If we reach this point, the printer was not online in time. */
        done_status = status;
        output_done();
    }
}

/*===========================================================================*
 *                              output_done                                  *
 *===========================================================================*/
PRIVATE void output_done()
{
/* Previous chunk of printing is finished.  Continue if OK and more.
 * Otherwise, reply to caller (FS).
 */
    register int status;

    if (!writing) return;               /* probably leftover interrupt */
    if (done_status != OK) {            /* printer error occurred */
        status = EIO;
        if ((done_status & ON_LINE) == 0) { 
            printf("Printer is not on line\n");
        } else if ((done_status & NO_PAPER)) { 
            printf("Printer is out of paper\n");
            status = EAGAIN;    
        } else {
            printf("Printer error, status is 0x%02X\n", done_status);
        }
        /* Some characters have been printed, tell how many. */
        if (status == EAGAIN && user_left < orig_count) {
                status = orig_count - user_left;
        }
        oleft = 0;                      /* cancel further output */
    } 
    else if (user_left != 0) {          /* not yet done, continue! */
        prepare_output();
        return;
    } 
    else {                              /* done! report back to FS */
        status = orig_count;
    }
    revive_pending = TRUE;
    revive_status = status;
    notify(caller);
}

/*===========================================================================*
 *                              do_status                                    *
 *===========================================================================*/
PRIVATE void do_status(m_ptr)
register message *m_ptr;        /* pointer to the newly arrived message */
{
  if (revive_pending) {
        m_ptr->m_type = DEV_REVIVE;             /* build message */
        m_ptr->REP_ENDPT = proc_nr;
        m_ptr->REP_STATUS = revive_status;

        writing = FALSE;                        /* unmark event */
        revive_pending = FALSE;                 /* unmark event */
  } else {
        m_ptr->m_type = DEV_NO_STATUS;
  }
  send(m_ptr->m_source, m_ptr);                 /* send the message */
}

/*===========================================================================*
 *                              do_cancel                                    *
 *===========================================================================*/
PRIVATE void do_cancel(m_ptr)
register message *m_ptr;        /* pointer to the newly arrived message */
{
/* Cancel a print request that has already started.  Usually this means that
 * the process doing the printing has been killed by a signal.  It is not
 * clear if there are race conditions.  Try not to cancel the wrong process,
 * but rely on FS to handle the EINTR reply and de-suspension properly.
 */

  if (writing && m_ptr->IO_ENDPT == proc_nr) {
        oleft = 0;              /* cancel output by interrupt handler */
        writing = FALSE;
        revive_pending = FALSE;
  }
  reply(TASK_REPLY, m_ptr->m_source, m_ptr->IO_ENDPT, EINTR);
}

/*===========================================================================*
 *                              reply                                        *
 *===========================================================================*/
PRIVATE void reply(code, replyee, process, status)
int code;                       /* TASK_REPLY or REVIVE */
int replyee;                    /* destination for message (normally FS) */
int process;                    /* which user requested the printing */
int status;                     /* number of  chars printed or error code */
{
/* Send a reply telling FS that printing has started or stopped. */

  message pr_mess;

  pr_mess.m_type = code;                /* TASK_REPLY or REVIVE */
  pr_mess.REP_STATUS = status;          /* count or EIO */
  pr_mess.REP_ENDPT = process;  /* which user does this pertain to */
  send(replyee, &pr_mess);              /* send the message */
}

/*===========================================================================*
 *                              do_initialize                                *
 *===========================================================================*/
PRIVATE void do_initialize()
{
/* Set global variables and initialize the printer. */
  static int initialized = FALSE;
  if (initialized) return;
  initialized = TRUE;
  
  /* Get the base port for first printer.  */
  sys_vircopy(SELF, BIOS_SEG, LPT1_IO_PORT_ADDR, 
        SELF, D, (vir_bytes) &port_base, LPT1_IO_PORT_SIZE);
  sys_outb(port_base + 2, INIT_PRINTER);
  tickdelay(1);                 /* easily satisfies Centronics minimum */
                                /* was 2 millisecs; now is ~17 millisecs */
  sys_outb(port_base + 2, PR_SELECT);
  irq_hook_id = 0;
  sys_irqsetpolicy(PRINTER_IRQ, 0, &irq_hook_id);
  sys_irqenable(&irq_hook_id);

}

/*==========================================================================*
 *                            prepare_output                                *
 *==========================================================================*/
PRIVATE void prepare_output()
{
/* Start next chunk of printer output. Fetch the data from user space. */

  register int chunk;

  if ( (chunk = user_left) > sizeof obuf) chunk = sizeof obuf;
  if (OK!=sys_datacopy(proc_nr, user_vir, SELF, (vir_bytes) obuf, chunk)) {
        done_status = EFAULT;
        output_done();
        return;
  }
  optr = obuf;
  oleft = chunk;
}

/*===========================================================================*
 *                              do_printer_output                                    *
 *===========================================================================*/
PRIVATE void do_printer_output()
{
/* This function does the actual output to the printer. This is called on
 * a HARD_INT message sent from the generic interrupt handler that 'forwards'
 * interrupts to this driver. The generic handler did not reenable the 
 * printer IRQ yet! 
 */

  unsigned long status;
  pvb_pair_t char_out[3];

  if (oleft == 0) {
        /* Nothing more to print.  Turn off printer interrupts in case they
         * are level-sensitive as on the PS/2.  This should be safe even
         * when the printer is busy with a previous character, because the
         * interrupt status does not affect the printer.
         */
        sys_outb(port_base + 2, PR_SELECT);
        sys_irqenable(&irq_hook_id);
        return;
  }

  do {
        /* Loop to handle fast (buffered) printers.  It is important that
         * processor interrupts are not disabled here, just printer interrupts.
         */
        (void) sys_inb(port_base + 1, &status);
        if ((status & STATUS_MASK) == BUSY_STATUS) {
                /* Still busy with last output.  This normally happens
                 * immediately after doing output to an unbuffered or slow
                 * printer.  It may happen after a call from prepare_output or
                 * pr_restart, since they are not synchronized with printer
                 * interrupts.  It may happen after a spurious interrupt.
                 */
                sys_irqenable(&irq_hook_id);
                return;
        }
        if ((status & STATUS_MASK) == NORMAL_STATUS) {
                /* Everything is all right.  Output another character. */
                pv_set(char_out[0], port_base, *optr++);        
                pv_set(char_out[1], port_base+2, ASSERT_STROBE);
                pv_set(char_out[2], port_base+2, NEGATE_STROBE);
                sys_voutb(char_out, 3); /* request series of port outb */

                user_vir++;
                user_left--;
        } else {
                /* Error.  This would be better ignored (treat as busy). */
                done_status = status;
                output_done();
                sys_irqenable(&irq_hook_id);
                return;
        }
  }
  while (--oleft != 0);

  /* Finished printing chunk OK. */
  done_status = OK;
  output_done();
  sys_irqenable(&irq_hook_id);
}

---