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 57 static int elcr_status; 58 int 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 */ 64 int 65 elcr_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 */ 94 enum intr_trigger 95 elcr_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 */ 110 void 111 elcr_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 } 129 130 void 131 elcr_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