1/*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3 *
4 * Copyright (c) 2004 John Baldwin <jhb@FreeBSD.org>
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 *    notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25 * SUCH DAMAGE.
26 */
27
28#include <sys/cdefs.h>
29__FBSDID("$FreeBSD$");
30
31/*
32 * The ELCR is a register that controls the trigger mode and polarity of
33 * EISA and ISA interrupts.  In FreeBSD 3.x and 4.x, the ELCR was only
34 * consulted for determining the appropriate trigger mode of EISA
35 * interrupts when using an APIC.  However, it seems that almost all
36 * systems that include PCI also include an ELCR that manages the ISA
37 * IRQs 0 through 15.  Thus, we check for the presence of an ELCR on
38 * every machine by checking to see if the values found at bootup are
39 * sane.  Note that the polarity of ISA and EISA IRQs are linked to the
40 * trigger mode.  All edge triggered IRQs use active-hi polarity, and
41 * all level triggered interrupts use active-lo polarity.
42 *
43 * The format of the ELCR is simple: it is a 16-bit bitmap where bit 0
44 * controls IRQ 0, bit 1 controls IRQ 1, etc.  If the bit is zero, the
45 * associated IRQ is edge triggered.  If the bit is one, the IRQ is
46 * level triggered.
47 */
48
49#include <sys/param.h>
50#include <sys/bus.h>
51#include <sys/systm.h>
52#include <machine/intr_machdep.h>
53
54#define	ELCR_PORT	0x4d0
55#define	ELCR_MASK(irq)	(1 << (irq))
56
57static int elcr_status;
58int elcr_found;
59
60/*
61 * Check to see if we have what looks like a valid ELCR.  We do this by
62 * verifying that IRQs 0, 1, 2, and 13 are all edge triggered.
63 */
64int
65elcr_probe(void)
66{
67	int i;
68
69	elcr_status = inb(ELCR_PORT) | inb(ELCR_PORT + 1) << 8;
70	if ((elcr_status & (ELCR_MASK(0) | ELCR_MASK(1) | ELCR_MASK(2) |
71	    ELCR_MASK(8) | ELCR_MASK(13))) != 0)
72		return (ENXIO);
73	if (bootverbose) {
74		printf("ELCR Found.  ISA IRQs programmed as:\n");
75		for (i = 0; i < 16; i++)
76			printf(" %2d", i);
77		printf("\n");
78		for (i = 0; i < 16; i++)
79			if (elcr_status & ELCR_MASK(i))
80				printf("  L");
81			else
82				printf("  E");
83		printf("\n");
84	}
85	if (resource_disabled("elcr", 0))
86		return (ENXIO);
87	elcr_found = 1;
88	return (0);
89}
90
91/*
92 * Returns 1 for level trigger, 0 for edge.
93 */
94enum intr_trigger
95elcr_read_trigger(u_int irq)
96{
97
98	KASSERT(elcr_found, ("%s: no ELCR was found!", __func__));
99	KASSERT(irq <= 15, ("%s: invalid IRQ %u", __func__, irq));
100	if (elcr_status & ELCR_MASK(irq))
101		return (INTR_TRIGGER_LEVEL);
102	else
103		return (INTR_TRIGGER_EDGE);
104}
105
106/*
107 * Set the trigger mode for a specified IRQ.  Mode of 0 means edge triggered,
108 * and a mode of 1 means level triggered.
109 */
110void
111elcr_write_trigger(u_int irq, enum intr_trigger trigger)
112{
113	int new_status;
114
115	KASSERT(elcr_found, ("%s: no ELCR was found!", __func__));
116	KASSERT(irq <= 15, ("%s: invalid IRQ %u", __func__, irq));
117	if (trigger == INTR_TRIGGER_LEVEL)
118		new_status = elcr_status | ELCR_MASK(irq);
119	else
120		new_status = elcr_status & ~ELCR_MASK(irq);
121	if (new_status == elcr_status)
122		return;
123	elcr_status = new_status;
124	if (irq >= 8)
125		outb(ELCR_PORT + 1, elcr_status >> 8);
126	else
127		outb(ELCR_PORT, elcr_status & 0xff);
128}
129
130void
131elcr_resume(void)
132{
133
134	KASSERT(elcr_found, ("%s: no ELCR was found!", __func__));
135	outb(ELCR_PORT, elcr_status & 0xff);
136	outb(ELCR_PORT + 1, elcr_status >> 8);
137}
138