This object may be used to represent a clock inside a clock tree.
A clock may be connected to another clock so that it receives update,
through a callback, whenever the source/parent clock is updated.
Although only the root clock of a clock tree controls the values
(represented as periods) of all clocks in tree, each clock holds
a local state containing the current value so that it can be fetched
independently. It will allows us to fullfill migration requirements
by migrating each clock independently of others.
This is based on the original work of Frederic Konrad.
Signed-off-by: Damien Hedde <damien.hedde@greensocs.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
Message-id: 20200406135251.157596-2-damien.hedde@greensocs.com
[PMM: Use uint64_t rather than unsigned long long in trace events;
the dtrace backend can't handle the latter]
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
hw/core/Makefile.objs | 1 +
include/hw/clock.h | 216 ++++++++++++++++++++++++++++++++++++++++++
hw/core/clock.c | 130 +++++++++++++++++++++++++
hw/core/trace-events | 7 ++
4 files changed, 354 insertions(+)
create mode 100644 include/hw/clock.h
create mode 100644 hw/core/clock.c
diff --git a/hw/core/Makefile.objs b/hw/core/Makefile.objs
index 6215e7c2085..1d9b0aa2057 100644
--- a/hw/core/Makefile.objs
+++ b/hw/core/Makefile.objs
@@ -7,6 +7,7 @@ common-obj-y += hotplug.o
common-obj-y += vmstate-if.o
# irq.o needed for qdev GPIO handling:
common-obj-y += irq.o
+common-obj-y += clock.o
common-obj-$(CONFIG_SOFTMMU) += reset.o
common-obj-$(CONFIG_SOFTMMU) += qdev-fw.o
diff --git a/include/hw/clock.h b/include/hw/clock.h
new file mode 100644
index 00000000000..82a7f3c6982
--- /dev/null
+++ b/include/hw/clock.h
@@ -0,0 +1,216 @@
+/*
+ * Hardware Clocks
+ *
+ * Copyright GreenSocs 2016-2020
+ *
+ * Authors:
+ * Frederic Konrad
+ * Damien Hedde
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#ifndef QEMU_HW_CLOCK_H
+#define QEMU_HW_CLOCK_H
+
+#include "qom/object.h"
+#include "qemu/queue.h"
+
+#define TYPE_CLOCK "clock"
+#define CLOCK(obj) OBJECT_CHECK(Clock, (obj), TYPE_CLOCK)
+
+typedef void ClockCallback(void *opaque);
+
+/*
+ * clock store a value representing the clock's period in 2^-32ns unit.
+ * It can represent:
+ * + periods from 2^-32ns up to 4seconds
+ * + frequency from ~0.25Hz 2e10Ghz
+ * Resolution of frequency representation decreases with frequency:
+ * + at 100MHz, resolution is ~2mHz
+ * + at 1Ghz, resolution is ~0.2Hz
+ * + at 10Ghz, resolution is ~20Hz
+ */
+#define CLOCK_SECOND (1000000000llu << 32)
+
+/*
+ * macro helpers to convert to hertz / nanosecond
+ */
+#define CLOCK_PERIOD_FROM_NS(ns) ((ns) * (CLOCK_SECOND / 1000000000llu))
+#define CLOCK_PERIOD_TO_NS(per) ((per) / (CLOCK_SECOND / 1000000000llu))
+#define CLOCK_PERIOD_FROM_HZ(hz) (((hz) != 0) ? CLOCK_SECOND / (hz) : 0u)