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* QEMU 8259 interrupt controller emulation
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* Copyright (c) 2003-2004 Fabrice Bellard
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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#include "monitor/monitor.h"
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#include "qemu/timer.h"
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#include "i8259_internal.h"
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#define DPRINTF(fmt, ...) \
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do { printf("pic: " fmt , ## __VA_ARGS__); } while (0)
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#define DPRINTF(fmt, ...)
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//#define DEBUG_IRQ_LATENCY
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//#define DEBUG_IRQ_COUNT
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#if defined(DEBUG_PIC) || defined(DEBUG_IRQ_COUNT)
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static int irq_level[16];
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#ifdef DEBUG_IRQ_COUNT
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static uint64_t irq_count[16];
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#ifdef DEBUG_IRQ_LATENCY
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static int64_t irq_time[16];
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static PICCommonState *slave_pic;
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/* return the highest priority found in mask (highest = smallest
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number). Return 8 if no irq */
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static int get_priority(PICCommonState *s, int mask)
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while ((mask & (1 << ((priority + s->priority_add) & 7))) == 0) {
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/* return the pic wanted interrupt. return -1 if none */
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static int pic_get_irq(PICCommonState *s)
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int mask, cur_priority, priority;
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mask = s->irr & ~s->imr;
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priority = get_priority(s, mask);
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/* compute current priority. If special fully nested mode on the
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master, the IRQ coming from the slave is not taken into account
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for the priority computation. */
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if (s->special_mask) {
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if (s->special_fully_nested_mode && s->master) {
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cur_priority = get_priority(s, mask);
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if (priority < cur_priority) {
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/* higher priority found: an irq should be generated */
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return (priority + s->priority_add) & 7;
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/* Update INT output. Must be called every time the output may have changed. */
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static void pic_update_irq(PICCommonState *s)
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irq = pic_get_irq(s);
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DPRINTF("pic%d: imr=%x irr=%x padd=%d\n",
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s->master ? 0 : 1, s->imr, s->irr, s->priority_add);
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qemu_irq_raise(s->int_out[0]);
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qemu_irq_lower(s->int_out[0]);
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/* set irq level. If an edge is detected, then the IRR is set to 1 */
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static void pic_set_irq(void *opaque, int irq, int level)
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PICCommonState *s = opaque;
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#if defined(DEBUG_PIC) || defined(DEBUG_IRQ_COUNT) || \
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defined(DEBUG_IRQ_LATENCY)
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int irq_index = s->master ? irq : irq + 8;
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#if defined(DEBUG_PIC) || defined(DEBUG_IRQ_COUNT)
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if (level != irq_level[irq_index]) {
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DPRINTF("pic_set_irq: irq=%d level=%d\n", irq_index, level);
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irq_level[irq_index] = level;
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#ifdef DEBUG_IRQ_COUNT
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irq_count[irq_index]++;
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#ifdef DEBUG_IRQ_LATENCY
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irq_time[irq_index] = qemu_get_clock_ns(vm_clock);
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if (s->elcr & mask) {
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/* level triggered */
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s->last_irr &= ~mask;
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if ((s->last_irr & mask) == 0) {
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s->last_irr &= ~mask;
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/* acknowledge interrupt 'irq' */
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static void pic_intack(PICCommonState *s, int irq)
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if (s->rotate_on_auto_eoi) {
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s->priority_add = (irq + 1) & 7;
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s->isr |= (1 << irq);
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/* We don't clear a level sensitive interrupt here */
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if (!(s->elcr & (1 << irq))) {
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s->irr &= ~(1 << irq);
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int pic_read_irq(DeviceState *d)
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PICCommonState *s = DO_UPCAST(PICCommonState, dev.qdev, d);
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int irq, irq2, intno;
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irq = pic_get_irq(s);
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irq2 = pic_get_irq(slave_pic);
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pic_intack(slave_pic, irq2);
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/* spurious IRQ on slave controller */
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intno = slave_pic->irq_base + irq2;
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intno = s->irq_base + irq;
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/* spurious IRQ on host controller */
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intno = s->irq_base + irq;
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#if defined(DEBUG_PIC) || defined(DEBUG_IRQ_LATENCY)
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#ifdef DEBUG_IRQ_LATENCY
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printf("IRQ%d latency=%0.3fus\n",
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(double)(qemu_get_clock_ns(vm_clock) -
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irq_time[irq]) * 1000000.0 / get_ticks_per_sec());
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DPRINTF("pic_interrupt: irq=%d\n", irq);
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static void pic_init_reset(PICCommonState *s)
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static void pic_reset(DeviceState *dev)
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PICCommonState *s = DO_UPCAST(PICCommonState, dev.qdev, dev);
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static void pic_ioport_write(void *opaque, hwaddr addr64,
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uint64_t val64, unsigned size)
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PICCommonState *s = opaque;
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uint32_t addr = addr64;
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uint32_t val = val64;
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int priority, cmd, irq;
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DPRINTF("write: addr=0x%02x val=0x%02x\n", addr, val);
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s->single_mode = val & 2;
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hw_error("level sensitive irq not supported");
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} else if (val & 0x08) {
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s->read_reg_select = val & 1;
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s->special_mask = (val >> 5) & 1;
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s->rotate_on_auto_eoi = cmd >> 2;
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case 1: /* end of interrupt */
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priority = get_priority(s, s->isr);
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irq = (priority + s->priority_add) & 7;
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s->isr &= ~(1 << irq);
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s->priority_add = (irq + 1) & 7;
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s->isr &= ~(1 << irq);
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s->priority_add = (val + 1) & 7;
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s->isr &= ~(1 << irq);
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s->priority_add = (irq + 1) & 7;
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switch (s->init_state) {
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s->irq_base = val & 0xf8;
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s->init_state = s->single_mode ? (s->init4 ? 3 : 0) : 2;
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s->special_fully_nested_mode = (val >> 4) & 1;
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s->auto_eoi = (val >> 1) & 1;
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static uint64_t pic_ioport_read(void *opaque, hwaddr addr,
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PICCommonState *s = opaque;
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ret = pic_get_irq(s);
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if (s->read_reg_select) {
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DPRINTF("read: addr=0x%02x val=0x%02x\n", addr, ret);
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int pic_get_output(DeviceState *d)
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PICCommonState *s = DO_UPCAST(PICCommonState, dev.qdev, d);
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return (pic_get_irq(s) >= 0);
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static void elcr_ioport_write(void *opaque, hwaddr addr,
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uint64_t val, unsigned size)
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PICCommonState *s = opaque;
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s->elcr = val & s->elcr_mask;
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static uint64_t elcr_ioport_read(void *opaque, hwaddr addr,
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PICCommonState *s = opaque;
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static const MemoryRegionOps pic_base_ioport_ops = {
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.read = pic_ioport_read,
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.write = pic_ioport_write,
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.min_access_size = 1,
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.max_access_size = 1,
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static const MemoryRegionOps pic_elcr_ioport_ops = {
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.read = elcr_ioport_read,
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.write = elcr_ioport_write,
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.min_access_size = 1,
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.max_access_size = 1,
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static void pic_init(PICCommonState *s)
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memory_region_init_io(&s->base_io, &pic_base_ioport_ops, s, "pic", 2);
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memory_region_init_io(&s->elcr_io, &pic_elcr_ioport_ops, s, "elcr", 1);
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qdev_init_gpio_out(&s->dev.qdev, s->int_out, ARRAY_SIZE(s->int_out));
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qdev_init_gpio_in(&s->dev.qdev, pic_set_irq, 8);
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void pic_info(Monitor *mon, const QDict *qdict)
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for (i = 0; i < 2; i++) {
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s = i == 0 ? DO_UPCAST(PICCommonState, dev.qdev, isa_pic) : slave_pic;
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monitor_printf(mon, "pic%d: irr=%02x imr=%02x isr=%02x hprio=%d "
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"irq_base=%02x rr_sel=%d elcr=%02x fnm=%d\n",
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i, s->irr, s->imr, s->isr, s->priority_add,
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s->irq_base, s->read_reg_select, s->elcr,
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s->special_fully_nested_mode);
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void irq_info(Monitor *mon, const QDict *qdict)
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#ifndef DEBUG_IRQ_COUNT
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monitor_printf(mon, "irq statistic code not compiled.\n");
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monitor_printf(mon, "IRQ statistics:\n");
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for (i = 0; i < 16; i++) {
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count = irq_count[i];
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monitor_printf(mon, "%2d: %" PRId64 "\n", i, count);
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qemu_irq *i8259_init(ISABus *bus, qemu_irq parent_irq)
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irq_set = g_malloc(ISA_NUM_IRQS * sizeof(qemu_irq));
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dev = i8259_init_chip("isa-i8259", bus, true);
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qdev_connect_gpio_out(&dev->qdev, 0, parent_irq);
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for (i = 0 ; i < 8; i++) {
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irq_set[i] = qdev_get_gpio_in(&dev->qdev, i);
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isa_pic = &dev->qdev;
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dev = i8259_init_chip("isa-i8259", bus, false);
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qdev_connect_gpio_out(&dev->qdev, 0, irq_set[2]);
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for (i = 0 ; i < 8; i++) {
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irq_set[i + 8] = qdev_get_gpio_in(&dev->qdev, i);
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slave_pic = DO_UPCAST(PICCommonState, dev, dev);
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static void i8259_class_init(ObjectClass *klass, void *data)
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PICCommonClass *k = PIC_COMMON_CLASS(klass);
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DeviceClass *dc = DEVICE_CLASS(klass);
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dc->reset = pic_reset;
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static const TypeInfo i8259_info = {
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.instance_size = sizeof(PICCommonState),
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.parent = TYPE_PIC_COMMON,
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.class_init = i8259_class_init,
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static void pic_register_types(void)
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type_register_static(&i8259_info);
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type_init(pic_register_types)