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-rw-r--r--hw/i8254.c297
1 files changed, 297 insertions, 0 deletions
diff --git a/hw/i8254.c b/hw/i8254.c
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index 0000000000..7dc5f3c25f
--- /dev/null
+++ b/hw/i8254.c
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+/*
+ * QEMU 8253/8254 interval timer emulation
+ *
+ * Copyright (c) 2003-2004 Fabrice Bellard
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+#include <stdlib.h>
+#include <stdio.h>
+#include <stdarg.h>
+#include <string.h>
+#include <getopt.h>
+#include <inttypes.h>
+#include <unistd.h>
+#include <sys/mman.h>
+#include <fcntl.h>
+#include <signal.h>
+#include <time.h>
+#include <sys/time.h>
+#include <malloc.h>
+#include <termios.h>
+#include <sys/poll.h>
+#include <errno.h>
+#include <sys/wait.h>
+#include <netinet/in.h>
+
+#include "cpu.h"
+#include "vl.h"
+
+#define RW_STATE_LSB 0
+#define RW_STATE_MSB 1
+#define RW_STATE_WORD0 2
+#define RW_STATE_WORD1 3
+#define RW_STATE_LATCHED_WORD0 4
+#define RW_STATE_LATCHED_WORD1 5
+
+PITChannelState pit_channels[3];
+
+static int pit_get_count(PITChannelState *s)
+{
+ uint64_t d;
+ int counter;
+
+ d = muldiv64(cpu_get_ticks() - s->count_load_time, PIT_FREQ, ticks_per_sec);
+ switch(s->mode) {
+ case 0:
+ case 1:
+ case 4:
+ case 5:
+ counter = (s->count - d) & 0xffff;
+ break;
+ case 3:
+ /* XXX: may be incorrect for odd counts */
+ counter = s->count - ((2 * d) % s->count);
+ break;
+ default:
+ counter = s->count - (d % s->count);
+ break;
+ }
+ return counter;
+}
+
+/* get pit output bit */
+int pit_get_out(PITChannelState *s)
+{
+ uint64_t d;
+ int out;
+
+ d = muldiv64(cpu_get_ticks() - s->count_load_time, PIT_FREQ, ticks_per_sec);
+ switch(s->mode) {
+ default:
+ case 0:
+ out = (d >= s->count);
+ break;
+ case 1:
+ out = (d < s->count);
+ break;
+ case 2:
+ if ((d % s->count) == 0 && d != 0)
+ out = 1;
+ else
+ out = 0;
+ break;
+ case 3:
+ out = (d % s->count) < ((s->count + 1) >> 1);
+ break;
+ case 4:
+ case 5:
+ out = (d == s->count);
+ break;
+ }
+ return out;
+}
+
+/* get the number of 0 to 1 transitions we had since we call this
+ function */
+/* XXX: maybe better to use ticks precision to avoid getting edges
+ twice if checks are done at very small intervals */
+int pit_get_out_edges(PITChannelState *s)
+{
+ uint64_t d1, d2;
+ int64_t ticks;
+ int ret, v;
+
+ ticks = cpu_get_ticks();
+ d1 = muldiv64(s->count_last_edge_check_time - s->count_load_time,
+ PIT_FREQ, ticks_per_sec);
+ d2 = muldiv64(ticks - s->count_load_time,
+ PIT_FREQ, ticks_per_sec);
+ s->count_last_edge_check_time = ticks;
+ switch(s->mode) {
+ default:
+ case 0:
+ if (d1 < s->count && d2 >= s->count)
+ ret = 1;
+ else
+ ret = 0;
+ break;
+ case 1:
+ ret = 0;
+ break;
+ case 2:
+ d1 /= s->count;
+ d2 /= s->count;
+ ret = d2 - d1;
+ break;
+ case 3:
+ v = s->count - ((s->count + 1) >> 1);
+ d1 = (d1 + v) / s->count;
+ d2 = (d2 + v) / s->count;
+ ret = d2 - d1;
+ break;
+ case 4:
+ case 5:
+ if (d1 < s->count && d2 >= s->count)
+ ret = 1;
+ else
+ ret = 0;
+ break;
+ }
+ return ret;
+}
+
+/* val must be 0 or 1 */
+void pit_set_gate(PITChannelState *s, int val)
+{
+ switch(s->mode) {
+ default:
+ case 0:
+ case 4:
+ /* XXX: just disable/enable counting */
+ break;
+ case 1:
+ case 5:
+ if (s->gate < val) {
+ /* restart counting on rising edge */
+ s->count_load_time = cpu_get_ticks();
+ s->count_last_edge_check_time = s->count_load_time;
+ }
+ break;
+ case 2:
+ case 3:
+ if (s->gate < val) {
+ /* restart counting on rising edge */
+ s->count_load_time = cpu_get_ticks();
+ s->count_last_edge_check_time = s->count_load_time;
+ }
+ /* XXX: disable/enable counting */
+ break;
+ }
+ s->gate = val;
+}
+
+static inline void pit_load_count(PITChannelState *s, int val)
+{
+ if (val == 0)
+ val = 0x10000;
+ s->count_load_time = cpu_get_ticks();
+ s->count_last_edge_check_time = s->count_load_time;
+ s->count = val;
+ if (s == &pit_channels[0] && val <= pit_min_timer_count) {
+ fprintf(stderr,
+ "\nWARNING: qemu: on your system, accurate timer emulation is impossible if its frequency is more than %d Hz. If using a 2.6 guest Linux kernel, you must patch asm/param.h to change HZ from 1000 to 100.\n\n",
+ PIT_FREQ / pit_min_timer_count);
+ }
+}
+
+void pit_ioport_write(CPUState *env, uint32_t addr, uint32_t val)
+{
+ int channel, access;
+ PITChannelState *s;
+
+ addr &= 3;
+ if (addr == 3) {
+ channel = val >> 6;
+ if (channel == 3)
+ return;
+ s = &pit_channels[channel];
+ access = (val >> 4) & 3;
+ switch(access) {
+ case 0:
+ s->latched_count = pit_get_count(s);
+ s->rw_state = RW_STATE_LATCHED_WORD0;
+ break;
+ default:
+ s->mode = (val >> 1) & 7;
+ s->bcd = val & 1;
+ s->rw_state = access - 1 + RW_STATE_LSB;
+ break;
+ }
+ } else {
+ s = &pit_channels[addr];
+ switch(s->rw_state) {
+ case RW_STATE_LSB:
+ pit_load_count(s, val);
+ break;
+ case RW_STATE_MSB:
+ pit_load_count(s, val << 8);
+ break;
+ case RW_STATE_WORD0:
+ case RW_STATE_WORD1:
+ if (s->rw_state & 1) {
+ pit_load_count(s, (s->latched_count & 0xff) | (val << 8));
+ } else {
+ s->latched_count = val;
+ }
+ s->rw_state ^= 1;
+ break;
+ }
+ }
+}
+
+uint32_t pit_ioport_read(CPUState *env, uint32_t addr)
+{
+ int ret, count;
+ PITChannelState *s;
+
+ addr &= 3;
+ s = &pit_channels[addr];
+ switch(s->rw_state) {
+ case RW_STATE_LSB:
+ case RW_STATE_MSB:
+ case RW_STATE_WORD0:
+ case RW_STATE_WORD1:
+ count = pit_get_count(s);
+ if (s->rw_state & 1)
+ ret = (count >> 8) & 0xff;
+ else
+ ret = count & 0xff;
+ if (s->rw_state & 2)
+ s->rw_state ^= 1;
+ break;
+ default:
+ case RW_STATE_LATCHED_WORD0:
+ case RW_STATE_LATCHED_WORD1:
+ if (s->rw_state & 1)
+ ret = s->latched_count >> 8;
+ else
+ ret = s->latched_count & 0xff;
+ s->rw_state ^= 1;
+ break;
+ }
+ return ret;
+}
+
+void pit_init(void)
+{
+ PITChannelState *s;
+ int i;
+
+ for(i = 0;i < 3; i++) {
+ s = &pit_channels[i];
+ s->mode = 3;
+ s->gate = (i != 2);
+ pit_load_count(s, 0);
+ }
+
+ register_ioport_write(0x40, 4, pit_ioport_write, 1);
+ register_ioport_read(0x40, 3, pit_ioport_read, 1);
+}
+
generated by cgit v1.2.3 (git 2.26.2) at 2024-12-17 16:49:46 +0000