diff options
Diffstat (limited to 'i386/i386at/gpl/linux/linux_autoirq.c')
| -rw-r--r-- | i386/i386at/gpl/linux/linux_autoirq.c | 161 |
1 files changed, 161 insertions, 0 deletions
diff --git a/i386/i386at/gpl/linux/linux_autoirq.c b/i386/i386at/gpl/linux/linux_autoirq.c new file mode 100644 index 00000000..2e3d4e61 --- /dev/null +++ b/i386/i386at/gpl/linux/linux_autoirq.c @@ -0,0 +1,161 @@ +/* + * 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); +} |