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/*
* Linux auto-irq support.
* Copyright (C) 1995 Shantanu Goel.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2, or (at your option)
* any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
*/
/*
* Written 1994 by Donald Becker.
*
* The author may be reached as becker@CESDIS.gsfc.nasa.gov, or C/O
* Center of Excellence in Space Data and Information Sciences
* Code 930.5, Goddard Space Flight Center, Greenbelt MD 20771
*
* This code is a general-purpose IRQ line detector for devices with
* jumpered IRQ lines. If you can make the device raise an IRQ (and
* that IRQ line isn't already being used), these routines will tell
* you what IRQ line it's using -- perfect for those oh-so-cool boot-time
* device probes!
*
* To use this, first call autoirq_setup(timeout). TIMEOUT is how many
* 'jiffies' (1/100 sec.) to detect other devices that have active IRQ lines,
* and can usually be zero at boot. 'autoirq_setup()' returns the bit
* vector of nominally-available IRQ lines (lines may be physically in-use,
* but not yet registered to a device).
* Next, set up your device to trigger an interrupt.
* Finally call autoirq_report(TIMEOUT) to find out which IRQ line was
* most recently active. The TIMEOUT should usually be zero, but may
* be set to the number of jiffies to wait for a slow device to raise an IRQ.
*
* The idea of using the setup timeout to filter out bogus IRQs came from
* the serial driver.
*/
#include <i386/pic.h>
#include <i386/ipl.h>
#include <linux/sched.h>
#include <linux/ptrace.h>
#include <asm/bitops.h>
#include <asm/system.h>
/*
* IRQ to network device map.
*/
void *irq2dev_map[16];
/*
* Set of fixed IRQs
* (fpu, rtc, com1, PIC slave cascade, keyboard, timer).
*/
int irqs_busy = 0x2147;
static volatile int irq_number; /* latest irq found */
static volatile int irq_bitmap; /* bitmap of IRQs found */
static int irq_handled; /* irq lines we have a handler on */
extern unsigned long loops_per_sec;
/*
* Interrupt handler when probing an IRQ.
*/
static void
autoirq_probe(irq)
int irq;
{
/*
* Mark this IRQ as the last one
* that interrupted and disable it.
*/
irq_number = irq;
set_bit(irq, (void *)&irq_bitmap);
disable_irq(irq);
}
/*
* Set up for auto-irq.
*/
int
autoirq_setup(waittime)
int waittime;
{
int i, mask;
int timeout = jiffies + waittime;
int boguscount = (waittime * loops_per_sec) / 100;
/*
* Allocate all possible IRQs.
*/
irq_handled = 0;
for (i = 0; i < 16; i++) {
if (test_bit(i, (void *)&irqs_busy) == 0
&& request_irq(i, autoirq_probe, 0, 0) == 0)
set_bit(i, (void *)&irq_handled);
}
irq_number = 0;
irq_bitmap = 0;
/*
* Hang out at least <waittime>
* jiffies waiting for bogus IRQ hits.
*/
while (timeout > jiffies && --boguscount > 0)
;
/*
* Free IRQs that caused bogus hits.
*/
for (i = 0, mask = 0x01; i < 16; i++, mask <<= 1) {
if (irq_bitmap & irq_handled & mask) {
irq_handled &= ~mask;
free_irq(i);
}
}
return (irq_handled);
}
/*
* Return the last IRQ that caused an interrupt.
*/
int
autoirq_report(waittime)
int waittime;
{
int i;
int timeout = jiffies + waittime;
int boguscount = (waittime * loops_per_sec) / 100;
/*
* Hang out at least <waittime>
* jiffies waiting for the IRQ.
*/
while (timeout > jiffies && --boguscount > 0)
if (irq_number)
break;
/*
* Retract the IRQ handlers that we handled.
*/
for (i = 0; i < 16; i++) {
if (test_bit(i, (void *)&irq_handled))
free_irq(i);
}
return (irq_number);
}
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