1 /* auto_irq.c: Auto-configure IRQ lines for linux. */
3 Written 1994 by Donald Becker.
5 The author may be reached as becker@scyld.com
7 This code is a general-purpose IRQ line detector for devices with
8 jumpered IRQ lines. If you can make the device raise an IRQ (and
9 that IRQ line isn't already being used), these routines will tell
10 you what IRQ line it's using -- perfect for those oh-so-cool boot-time
13 To use this, first call autoirq_setup(timeout). TIMEOUT is how many
14 'jiffies' (1/100 sec.) to detect other devices that have active IRQ lines,
15 and can usually be zero at boot. 'autoirq_setup()' returns the bit
16 vector of nominally-available IRQ lines (lines may be physically in-use,
17 but not yet registered to a device).
18 Next, set up your device to trigger an interrupt.
19 Finally call autoirq_report(TIMEOUT) to find out which IRQ line was
20 most recently active. The TIMEOUT should usually be zero, but may
21 be set to the number of jiffies to wait for a slow device to raise an IRQ.
23 The idea of using the setup timeout to filter out bogus IRQs came from
29 static const char *version=
30 "auto_irq.c:v1.11 Donald Becker (becker@scyld.com)";
33 #include <linux/module.h>
34 #include <linux/jiffies.h>
35 #include <linux/delay.h>
36 #include <asm/bitops.h>
39 #include <linux/netdevice.h>
41 static unsigned long irqs;
43 void autoirq_setup(int waittime)
45 irqs = probe_irq_on();
48 #define BUSY_LOOP_UNTIL(j) while ((long)(jiffies-(j)) < 0) ;
49 int autoirq_report(int waittime)
51 unsigned long delay = jiffies + waittime;
52 BUSY_LOOP_UNTIL(delay)
53 return probe_irq_off(irqs);
56 EXPORT_SYMBOL(autoirq_setup);
57 EXPORT_SYMBOL(autoirq_report);
62 * compile-command: "gcc -DKERNEL -Wall -O6 -fomit-frame-pointer -I/usr/src/linux/net/tcp -c auto_irq.c"
64 * kept-new-versions: 5