/*-
* SPDX-License-Identifier: BSD-2-Clause
*
* Copyright (c) 2004 John Baldwin <jhb@FreeBSD.org>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <sys/cdefs.h>
/*
* The ELCR is a register that controls the trigger mode and polarity of
* EISA and ISA interrupts. In FreeBSD 3.x and 4.x, the ELCR was only
* consulted for determining the appropriate trigger mode of EISA
* interrupts when using an APIC. However, it seems that almost all
* systems that include PCI also include an ELCR that manages the ISA
* IRQs 0 through 15. Thus, we check for the presence of an ELCR on
* every machine by checking to see if the values found at bootup are
* sane. Note that the polarity of ISA and EISA IRQs are linked to the
* trigger mode. All edge triggered IRQs use active-hi polarity, and
* all level triggered interrupts use active-lo polarity.
*
* The format of the ELCR is simple: it is a 16-bit bitmap where bit 0
* controls IRQ 0, bit 1 controls IRQ 1, etc. If the bit is zero, the
* associated IRQ is edge triggered. If the bit is one, the IRQ is
* level triggered.
*/
#include <sys/param.h>
#include <sys/bus.h>
#include <sys/systm.h>
#include <machine/intr_machdep.h>
#define ELCR_PORT 0x4d0
#define ELCR_MASK(irq) (1 << (irq))
static int elcr_status;
int elcr_found;
/*
* Check to see if we have what looks like a valid ELCR. We do this by
* verifying that IRQs 0, 1, 2, and 13 are all edge triggered.
*/
int
elcr_probe(void)
{
int i;
elcr_status = inb(ELCR_PORT) | inb(ELCR_PORT + 1) << 8;
if ((elcr_status & (ELCR_MASK(0) | ELCR_MASK(1) | ELCR_MASK(2) |
ELCR_MASK(8) | ELCR_MASK(13))) != 0)
return (ENXIO);
if (bootverbose) {
printf("ELCR Found. ISA IRQs programmed as:\n");
for (i = 0; i < 16; i++)
printf(" %2d", i);
printf("\n");
for (i = 0; i < 16; i++)
if (elcr_status & ELCR_MASK(i))
printf(" L");
else
printf(" E");
printf("\n");
}
if (resource_disabled("elcr", 0))
return (ENXIO);
elcr_found = 1;
return (0);
}
/*
* Returns 1 for level trigger, 0 for edge.
*/
enum intr_trigger
elcr_read_trigger(u_int irq)
{
KASSERT(elcr_found, ("%s: no ELCR was found!", __func__));
KASSERT(irq <= 15, ("%s: invalid IRQ %u", __func__, irq));
if (elcr_status & ELCR_MASK(irq))
return (INTR_TRIGGER_LEVEL);
else
return (INTR_TRIGGER_EDGE);
}
/*
* Set the trigger mode for a specified IRQ. Mode of 0 means edge triggered,
* and a mode of 1 means level triggered.
*/
void
elcr_write_trigger(u_int irq, enum intr_trigger trigger)
{
int new_status;
KASSERT(elcr_found, ("%s: no ELCR was found!", __func__));
KASSERT(irq <= 15, ("%s: invalid IRQ %u", __func__, irq));
if (trigger == INTR_TRIGGER_LEVEL)
new_status = elcr_status | ELCR_MASK(irq);
else
new_status = elcr_status & ~ELCR_MASK(irq);
if (new_status == elcr_status)
return;
elcr_status = new_status;
if (irq >= 8)
outb(ELCR_PORT + 1, elcr_status >> 8);
else
outb(ELCR_PORT, elcr_status & 0xff);
}
void
elcr_resume(void)
{
KASSERT(elcr_found, ("%s: no ELCR was found!", __func__));
outb(ELCR_PORT, elcr_status & 0xff);
outb(ELCR_PORT + 1, elcr_status >> 8);
}
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