[PATCH 3/4] Add support for HPET periodic timer.

Luca Tettamanti
2007-08-17T23:11:52Z

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Linux operates the HPET timer in legacy replacement mode, which means that
the periodic interrupt of the CMOS RTC is not delivered (qemu won't be able
to use /dev/rtc). Add support for HPET (/dev/hpet) as a replacement for the
RTC; the periodic interrupt is delivered via SIGIO and is handled in the
same way as the RTC timer.

Signed-off-by: Luca Tettamanti <kronos.it-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>

---
vl.c | 57 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 56 insertions(+), 1 deletion(-)

Index: qemu/vl.c
===================================================================
--- qemu.orig/vl.c 2007-08-17 17:39:21.000000000 +0200
+++ qemu/vl.c 2007-08-18 00:40:16.000000000 +0200
@@ -56,6 +56,7 @@
#include <pty.h>
#include <malloc.h>
#include <linux/rtc.h>
+#include <linux/hpet.h>
#include <linux/ppdev.h>
#include <linux/parport.h>
#else
@@ -809,6 +810,9 @@

#ifdef __linux__

+static int hpet_start_timer(struct qemu_alarm_timer *t);
+static void hpet_stop_timer(struct qemu_alarm_timer *t);
+
static int rtc_start_timer(struct qemu_alarm_timer *t);
static void rtc_stop_timer(struct qemu_alarm_timer *t);

@@ -818,7 +822,9 @@

static struct qemu_alarm_timer alarm_timers[] = {
#ifdef __linux__
- /* RTC - if available - is preferred */
+ /* HPET - if available - is preferred */
+ {"hpet", hpet_start_timer, hpet_stop_timer, NULL},
+ /* ...otherwise try RTC */
{"rtc", rtc_start_timer, rtc_stop_timer, NULL},
#endif
#ifndef _WIN32
@@ -1153,6 +1159,55 @@
fcntl(fd, F_SETOWN, getpid());
}

+static int hpet_start_timer(struct qemu_alarm_timer *t)
+{
+ struct hpet_info info;
+ int r, fd;
+
+ fd = open("/dev/hpet", O_RDONLY);
+ if (fd < 0)
+ return -1;
+
+ /* Set frequency */
+ r = ioctl(fd, HPET_IRQFREQ, RTC_FREQ);
+ if (r < 0) {
+ fprintf(stderr, "Could not configure '/dev/hpet' to have a 1024Hz timer. This is not a fatal\n"
+ "error, but for better emulation accuracy type:\n"
+ "'echo 1024 > /proc/sys/dev/hpet/max-user-freq' as root.\n");
+ goto fail;
+ }
+
+ /* Check capabilities */
+ r = ioctl(fd, HPET_INFO, &info);
+ if (r < 0)
+ goto fail;
+
+ /* Enable periodic mode */
+ r = ioctl(fd, HPET_EPI, 0);
+ if (info.hi_flags && (r < 0))
+ goto fail;
+
+ /* Enable interrupt */
+ r = ioctl(fd, HPET_IE_ON, 0);
+ if (r < 0)
+ goto fail;
+
+ enable_sigio_timer(fd);
+ t->priv = (void *)fd;
+
+ return 0;
+fail:
+ close(fd);
+ return -1;
+}
+
+static void hpet_stop_timer(struct qemu_alarm_timer *t)
+{
+ int fd = (int)t->priv;
+
+ close(fd);
+}
+
static int rtc_start_timer(struct qemu_alarm_timer *t)
{
int rtc_fd;

--