1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause 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 /* 30 * The ELCR is a register that controls the trigger mode and polarity of 31 * EISA and ISA interrupts. In FreeBSD 3.x and 4.x, the ELCR was only 32 * consulted for determining the appropriate trigger mode of EISA 33 * interrupts when using an APIC. However, it seems that almost all 34 * systems that include PCI also include an ELCR that manages the ISA 35 * IRQs 0 through 15. Thus, we check for the presence of an ELCR on 36 * every machine by checking to see if the values found at bootup are 37 * sane. Note that the polarity of ISA and EISA IRQs are linked to the 38 * trigger mode. All edge triggered IRQs use active-hi polarity, and 39 * all level triggered interrupts use active-lo polarity. 40 * 41 * The format of the ELCR is simple: it is a 16-bit bitmap where bit 0 42 * controls IRQ 0, bit 1 controls IRQ 1, etc. If the bit is zero, the 43 * associated IRQ is edge triggered. If the bit is one, the IRQ is 44 * level triggered. 45 */ 46 47 #include <sys/param.h> 48 #include <sys/bus.h> 49 #include <sys/systm.h> 50 #include <machine/intr_machdep.h> 51 52 #define ELCR_PORT 0x4d0 53 #define ELCR_MASK(irq) (1 << (irq)) 54 55 static int elcr_status; 56 int elcr_found; 57 58 /* 59 * Check to see if we have what looks like a valid ELCR. We do this by 60 * verifying that IRQs 0, 1, 2, and 13 are all edge triggered. 61 */ 62 int 63 elcr_probe(void) 64 { 65 int i; 66 67 elcr_status = inb(ELCR_PORT) | inb(ELCR_PORT + 1) << 8; 68 if ((elcr_status & (ELCR_MASK(0) | ELCR_MASK(1) | ELCR_MASK(2) | 69 ELCR_MASK(8) | ELCR_MASK(13))) != 0) 70 return (ENXIO); 71 if (bootverbose) { 72 printf("ELCR Found. ISA IRQs programmed as:\n"); 73 for (i = 0; i < 16; i++) 74 printf(" %2d", i); 75 printf("\n"); 76 for (i = 0; i < 16; i++) 77 if (elcr_status & ELCR_MASK(i)) 78 printf(" L"); 79 else 80 printf(" E"); 81 printf("\n"); 82 } 83 if (resource_disabled("elcr", 0)) 84 return (ENXIO); 85 elcr_found = 1; 86 return (0); 87 } 88 89 /* 90 * Returns 1 for level trigger, 0 for edge. 91 */ 92 enum intr_trigger 93 elcr_read_trigger(u_int irq) 94 { 95 96 KASSERT(elcr_found, ("%s: no ELCR was found!", __func__)); 97 KASSERT(irq <= 15, ("%s: invalid IRQ %u", __func__, irq)); 98 if (elcr_status & ELCR_MASK(irq)) 99 return (INTR_TRIGGER_LEVEL); 100 else 101 return (INTR_TRIGGER_EDGE); 102 } 103 104 /* 105 * Set the trigger mode for a specified IRQ. Mode of 0 means edge triggered, 106 * and a mode of 1 means level triggered. 107 */ 108 void 109 elcr_write_trigger(u_int irq, enum intr_trigger trigger) 110 { 111 int new_status; 112 113 KASSERT(elcr_found, ("%s: no ELCR was found!", __func__)); 114 KASSERT(irq <= 15, ("%s: invalid IRQ %u", __func__, irq)); 115 if (trigger == INTR_TRIGGER_LEVEL) 116 new_status = elcr_status | ELCR_MASK(irq); 117 else 118 new_status = elcr_status & ~ELCR_MASK(irq); 119 if (new_status == elcr_status) 120 return; 121 elcr_status = new_status; 122 if (irq >= 8) 123 outb(ELCR_PORT + 1, elcr_status >> 8); 124 else 125 outb(ELCR_PORT, elcr_status & 0xff); 126 } 127 128 void 129 elcr_resume(void) 130 { 131 132 KASSERT(elcr_found, ("%s: no ELCR was found!", __func__)); 133 outb(ELCR_PORT, elcr_status & 0xff); 134 outb(ELCR_PORT + 1, elcr_status >> 8); 135 } 136