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printer: perform probe on startup

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This stops the printer driver from hanging the entire system when
/dev/lp is opened on systems that do not have a parallel port. With
this change, the printer driver shuts down immediately after loading
on such systems.
This commit is contained in:
David van Moolenbroek 2011-12-05 10:54:58 +01:00
parent ed007ca416
commit 67c012b3fc
1 changed files with 23 additions and 5 deletions
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28
drivers/printer/printer.c
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@ -107,6 +107,7 @@ 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( int do_probe, (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) );
@ -193,6 +194,11 @@ PRIVATE void sef_local_startup()
PRIVATE int sef_cb_init_fresh(int UNUSED(type), sef_init_info_t *UNUSED(info))
{
/* Initialize the printer driver. */
/* If no printer is present, do not start. */
if (!do_probe())
return ENODEV; /* arbitrary error code */
/* Announce we are up! */
chardriver_announce();
@ -352,6 +358,23 @@ int status; /* number of chars printed or error code */
send(replyee, &pr_mess); /* send the message */
}
/*===========================================================================*
* do_probe *
*===========================================================================*/
PRIVATE int do_probe(void)
{
/* See if there is a printer at all. */
/* Get the base port for first printer. */
if(sys_vircopy(SELF, BIOS_SEG, LPT1_IO_PORT_ADDR,
SELF, D, (vir_bytes) &port_base, LPT1_IO_PORT_SIZE) != OK) {
panic("do_initialize: sys_vircopy failed");
}
/* If the port is zero, the parallel port is not available at all. */
return (port_base != 0);
}
/*===========================================================================*
* do_initialize *
*===========================================================================*/
@ -362,11 +385,6 @@ PRIVATE void do_initialize()
if (initialized) return;
initialized = TRUE;
/* Get the base port for first printer. */
if(sys_vircopy(SELF, BIOS_SEG, LPT1_IO_PORT_ADDR,
SELF, D, (vir_bytes) &port_base, LPT1_IO_PORT_SIZE) != OK) {
panic("do_initialize: sys_vircopy failed");
}
if(sys_outb(port_base + 2, INIT_PRINTER) != OK) {
printf("printer: sys_outb of %x failed\n", port_base+2);
panic("do_initialize: sys_outb init failed");