116 lines
3.5 KiB
C
116 lines
3.5 KiB
C
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/* auto_irq.c: Auto-configure IRQ lines for linux. */
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/*
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Written 1993 by Donald Becker.
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The Author may be reached as becker@super.org or
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C/O Supercomputing Research Ctr., 17100 Science Dr., Bowie MD 20715
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This code is a general-purpose IRQ line detector for devices with
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jumpered IRQ lines. If you can make the device raise an IRQ (and
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that IRQ line isn't already being used), these routines will tell
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you what IRQ line it's using -- perfect for those oh-so-cool boot-time
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device probes!
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To use this, first call autoirq_setup(timeout). TIMEOUT is how many
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'jiffies' (1/18 sec.) to detect other devices that have active IRQ lines,
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and can usually be zero at boot. 'autoirq_setup()' returns the bit
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vector of nominally-available IRQ lines (lines may be physically in-use,
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but not yet registered to a device).
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Next, set up your device to trigger an interrupt.
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Finally call autoirq_report(TIMEOUT) to find out which IRQ line was
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most recently active. The TIMEOUT should usually be zero, but may
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be set to the number of jiffies to wait for a slow device to raise an IRQ.
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The idea of using the setup timeout to filter out bogus IRQs came from
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the serial driver.
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*/
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#ifdef version
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static char *version="auto_irq.c:v0.02 1993 Donald Becker (becker@super.org)";
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#endif
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/*#include <linux/config.h>*/
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/*#include <linux/kernel.h>*/
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#include <linux/sched.h>
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#include <asm/bitops.h>
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#include <asm/io.h>
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#include "dev.h"
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/*#include <asm/system.h>*/
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struct device *irq2dev_map[16] = {0, 0, /* ... zeroed */};
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int irqs_busy = 0x01; /* The set of fixed IRQs always enabled */
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int irqs_used = 0x01; /* The set of fixed IRQs sometimes enabled. */
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int irqs_reserved = 0x00; /* An advisory "reserved" table. */
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int irqs_shared = 0x00; /* IRQ lines "shared" among conforming cards.*/
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static volatile int irq_number; /* The latest irq number we actually found. */
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static volatile int irq_bitmap; /* The irqs we actually found. */
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static int irq_handled; /* The irq lines we have a handler on. */
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static void autoirq_probe(int irq)
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{
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irq_number = irq;
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set_bit(irq, (void *)&irq_bitmap); /* irq_bitmap |= 1 << irq; */
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return;
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}
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struct sigaction autoirq_sigaction = { autoirq_probe, 0, SA_INTERRUPT, NULL};
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int autoirq_setup(int waittime)
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{
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int i, mask;
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int timeout = jiffies+waittime;
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irq_number = 0;
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irq_bitmap = 0;
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irq_handled = 0;
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for (i = 0; i < 16; i++) {
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if (!irqaction(i, &autoirq_sigaction))
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set_bit(i, (void *)&irq_handled); /* irq_handled |= 1 << i;*/
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}
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/* Update our USED lists. */
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irqs_used |= ~irq_handled;
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/* Hang out at least <waittime> jiffies waiting for bogus IRQ hits. */
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while (timeout > jiffies)
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;
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for (i = 0, mask = 0x01; i < 16; i++, mask <<= 1) {
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if (irq_bitmap & irq_handled & mask) {
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irq_handled &= ~mask;
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#ifdef notdef
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printk(" Spurious interrupt on IRQ %d\n", i);
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#endif
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free_irq(i);
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}
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}
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return irq_handled;
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}
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int autoirq_report(int waittime)
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{
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int i;
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int timeout = jiffies+waittime;
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/* Hang out at least <waittime> jiffies waiting for the IRQ. */
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while (timeout > jiffies)
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if (irq_number)
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break;
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/* Retract the irq handlers that we installed. */
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for (i = 0; i < 16; i++) {
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if (test_bit(i, (void *)&irq_handled))
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free_irq(i);
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}
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return irq_number;
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}
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/*
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* Local variables:
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* compile-command: "gcc -DKERNEL -Wall -O6 -fomit-frame-pointer -I/usr/src/linux/net/tcp -c auto_irq.c"
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* version-control: t
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* kept-new-versions: 5
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* End:
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*/
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