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