1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD 3 * 4 * Copyright (c) 2004 John Baldwin <jhb@FreeBSD.org> 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26 * SUCH DAMAGE. 27 */ 28 29 #include <sys/cdefs.h> 30 __FBSDID("$FreeBSD$"); 31 32 /* 33 * The ELCR is a register that controls the trigger mode and polarity of 34 * EISA and ISA interrupts. In FreeBSD 3.x and 4.x, the ELCR was only 35 * consulted for determining the appropriate trigger mode of EISA 36 * interrupts when using an APIC. However, it seems that almost all 37 * systems that include PCI also include an ELCR that manages the ISA 38 * IRQs 0 through 15. Thus, we check for the presence of an ELCR on 39 * every machine by checking to see if the values found at bootup are 40 * sane. Note that the polarity of ISA and EISA IRQs are linked to the 41 * trigger mode. All edge triggered IRQs use active-hi polarity, and 42 * all level triggered interrupts use active-lo polarity. 43 * 44 * The format of the ELCR is simple: it is a 16-bit bitmap where bit 0 45 * controls IRQ 0, bit 1 controls IRQ 1, etc. If the bit is zero, the 46 * associated IRQ is edge triggered. If the bit is one, the IRQ is 47 * level triggered. 48 */ 49 50 #include <sys/param.h> 51 #include <sys/bus.h> 52 #include <sys/systm.h> 53 #include <machine/intr_machdep.h> 54 55 #define ELCR_PORT 0x4d0 56 #define ELCR_MASK(irq) (1 << (irq)) 57 58 static int elcr_status; 59 int elcr_found; 60 61 /* 62 * Check to see if we have what looks like a valid ELCR. We do this by 63 * verifying that IRQs 0, 1, 2, and 13 are all edge triggered. 64 */ 65 int 66 elcr_probe(void) 67 { 68 int i; 69 70 elcr_status = inb(ELCR_PORT) | inb(ELCR_PORT + 1) << 8; 71 if ((elcr_status & (ELCR_MASK(0) | ELCR_MASK(1) | ELCR_MASK(2) | 72 ELCR_MASK(8) | ELCR_MASK(13))) != 0) 73 return (ENXIO); 74 if (bootverbose) { 75 printf("ELCR Found. ISA IRQs programmed as:\n"); 76 for (i = 0; i < 16; i++) 77 printf(" %2d", i); 78 printf("\n"); 79 for (i = 0; i < 16; i++) 80 if (elcr_status & ELCR_MASK(i)) 81 printf(" L"); 82 else 83 printf(" E"); 84 printf("\n"); 85 } 86 if (resource_disabled("elcr", 0)) 87 return (ENXIO); 88 elcr_found = 1; 89 return (0); 90 } 91 92 /* 93 * Returns 1 for level trigger, 0 for edge. 94 */ 95 enum intr_trigger 96 elcr_read_trigger(u_int irq) 97 { 98 99 KASSERT(elcr_found, ("%s: no ELCR was found!", __func__)); 100 KASSERT(irq <= 15, ("%s: invalid IRQ %u", __func__, irq)); 101 if (elcr_status & ELCR_MASK(irq)) 102 return (INTR_TRIGGER_LEVEL); 103 else 104 return (INTR_TRIGGER_EDGE); 105 } 106 107 /* 108 * Set the trigger mode for a specified IRQ. Mode of 0 means edge triggered, 109 * and a mode of 1 means level triggered. 110 */ 111 void 112 elcr_write_trigger(u_int irq, enum intr_trigger trigger) 113 { 114 int new_status; 115 116 KASSERT(elcr_found, ("%s: no ELCR was found!", __func__)); 117 KASSERT(irq <= 15, ("%s: invalid IRQ %u", __func__, irq)); 118 if (trigger == INTR_TRIGGER_LEVEL) 119 new_status = elcr_status | ELCR_MASK(irq); 120 else 121 new_status = elcr_status & ~ELCR_MASK(irq); 122 if (new_status == elcr_status) 123 return; 124 elcr_status = new_status; 125 if (irq >= 8) 126 outb(ELCR_PORT + 1, elcr_status >> 8); 127 else 128 outb(ELCR_PORT, elcr_status & 0xff); 129 } 130 131 void 132 elcr_resume(void) 133 { 134 135 KASSERT(elcr_found, ("%s: no ELCR was found!", __func__)); 136 outb(ELCR_PORT, elcr_status & 0xff); 137 outb(ELCR_PORT + 1, elcr_status >> 8); 138 } 139