qdev: add clock input&output support to devices.

Add functions to easily handle clocks with devices.
Clock inputs and outputs should be used to handle clock propagation
between devices.
The API is very similar the GPIO API.

This is based on the original work of Frederic Konrad.

Signed-off-by: Damien Hedde <damien.hedde@greensocs.com>
Reviewed-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-id: 20200406135251.157596-4-damien.hedde@greensocs.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

hw/core/Makefile.objs

@@ -7,7 +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-y += clock.o qdev-clock.o
 
 common-obj-$(CONFIG_SOFTMMU) += reset.o
 common-obj-$(CONFIG_SOFTMMU) += qdev-fw.o

hw/core/qdev-clock.c

@@ -0,0 +1,168 @@
+/*
+ * Device's clock input and output
+ *
+ * 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.
+ */
+
+#include "qemu/osdep.h"
+#include "hw/qdev-clock.h"
+#include "hw/qdev-core.h"
+#include "qapi/error.h"
+
+/*
+ * qdev_init_clocklist:
+ * Add a new clock in a device
+ */
+static NamedClockList *qdev_init_clocklist(DeviceState *dev, const char *name,
+                                           bool output, Clock *clk)
+{
+    NamedClockList *ncl;
+
+    /*
+     * Clock must be added before realize() so that we can compute the
+     * clock's canonical path during device_realize().
+     */
+    assert(!dev->realized);
+
+    /*
+     * The ncl structure is freed by qdev_finalize_clocklist() which will
+     * be called during @dev's device_finalize().
+     */
+    ncl = g_new0(NamedClockList, 1);
+    ncl->name = g_strdup(name);
+    ncl->output = output;
+    ncl->alias = (clk != NULL);
+
+    /*
+     * Trying to create a clock whose name clashes with some other
+     * clock or property is a bug in the caller and we will abort().
+     */
+    if (clk == NULL) {
+        clk = CLOCK(object_new(TYPE_CLOCK));
+        object_property_add_child(OBJECT(dev), name, OBJECT(clk), &error_abort);
+        if (output) {
+            /*
+             * Remove object_new()'s initial reference.
+             * Note that for inputs, the reference created by object_new()
+             * will be deleted in qdev_finalize_clocklist().
+             */
+            object_unref(OBJECT(clk));
+        }
+    } else {
+        object_property_add_link(OBJECT(dev), name,
+                                 object_get_typename(OBJECT(clk)),
+                                 (Object **) &ncl->clock,
+                                 NULL, OBJ_PROP_LINK_STRONG, &error_abort);
+    }
+
+    ncl->clock = clk;
+
+    QLIST_INSERT_HEAD(&dev->clocks, ncl, node);
+    return ncl;
+}
+
+void qdev_finalize_clocklist(DeviceState *dev)
+{
+    /* called by @dev's device_finalize() */
+    NamedClockList *ncl, *ncl_next;
+
+    QLIST_FOREACH_SAFE(ncl, &dev->clocks, node, ncl_next) {
+        QLIST_REMOVE(ncl, node);
+        if (!ncl->output && !ncl->alias) {
+            /*
+             * We kept a reference on the input clock to ensure it lives up to
+             * this point so we can safely remove the callback.
+             * It avoids having a callback to a deleted object if ncl->clock
+             * is still referenced somewhere else (eg: by a clock output).
+             */
+            clock_clear_callback(ncl->clock);
+            object_unref(OBJECT(ncl->clock));
+        }
+        g_free(ncl->name);
+        g_free(ncl);
+    }
+}
+
+Clock *qdev_init_clock_out(DeviceState *dev, const char *name)
+{
+    NamedClockList *ncl;
+
+    assert(name);
+
+    ncl = qdev_init_clocklist(dev, name, true, NULL);
+
+    return ncl->clock;
+}
+
+Clock *qdev_init_clock_in(DeviceState *dev, const char *name,
+                            ClockCallback *callback, void *opaque)
+{
+    NamedClockList *ncl;
+
+    assert(name);
+
+    ncl = qdev_init_clocklist(dev, name, false, NULL);
+
+    if (callback) {
+        clock_set_callback(ncl->clock, callback, opaque);
+    }
+    return ncl->clock;
+}
+
+static NamedClockList *qdev_get_clocklist(DeviceState *dev, const char *name)
+{
+    NamedClockList *ncl;
+
+    QLIST_FOREACH(ncl, &dev->clocks, node) {
+        if (strcmp(name, ncl->name) == 0) {
+            return ncl;
+        }
+    }
+
+    return NULL;
+}
+
+Clock *qdev_get_clock_in(DeviceState *dev, const char *name)
+{
+    NamedClockList *ncl;
+
+    assert(name);
+
+    ncl = qdev_get_clocklist(dev, name);
+    assert(!ncl->output);
+
+    return ncl->clock;
+}
+
+Clock *qdev_get_clock_out(DeviceState *dev, const char *name)
+{
+    NamedClockList *ncl;
+
+    assert(name);
+
+    ncl = qdev_get_clocklist(dev, name);
+    assert(ncl->output);
+
+    return ncl->clock;
+}
+
+Clock *qdev_alias_clock(DeviceState *dev, const char *name,
+                        DeviceState *alias_dev, const char *alias_name)
+{
+    NamedClockList *ncl;
+
+    assert(name && alias_name);
+
+    ncl = qdev_get_clocklist(dev, name);
+
+    qdev_init_clocklist(alias_dev, alias_name, ncl->output, ncl->clock);
+
+    return ncl->clock;
+}

hw/core/qdev.c

@@ -37,6 +37,7 @@
 #include "hw/qdev-properties.h"
 #include "hw/boards.h"
 #include "hw/sysbus.h"
+#include "hw/qdev-clock.h"
 #include "migration/vmstate.h"
 #include "trace.h"
 
@@ -855,6 +856,7 @@ static void device_set_realized(Object *obj, bool value, Error **errp)
     DeviceClass *dc = DEVICE_GET_CLASS(dev);
     HotplugHandler *hotplug_ctrl;
     BusState *bus;
+    NamedClockList *ncl;
     Error *local_err = NULL;
     bool unattached_parent = false;
     static int unattached_count;
@@ -902,6 +904,13 @@ static void device_set_realized(Object *obj, bool value, Error **errp)
          */
         g_free(dev->canonical_path);
         dev->canonical_path = object_get_canonical_path(OBJECT(dev));
+        QLIST_FOREACH(ncl, &dev->clocks, node) {
+            if (ncl->alias) {
+                continue;
+            } else {
+                clock_setup_canonical_path(ncl->clock);
+            }
+        }
 
         if (qdev_get_vmsd(dev)) {
             if (vmstate_register_with_alias_id(VMSTATE_IF(dev),
@@ -1025,6 +1034,7 @@ static void device_initfn(Object *obj)
     dev->allow_unplug_during_migration = false;
 
     QLIST_INIT(&dev->gpios);
+    QLIST_INIT(&dev->clocks);
 }
 
 static void device_post_init(Object *obj)
@@ -1054,6 +1064,8 @@ static void device_finalize(Object *obj)
          */
     }
 
+    qdev_finalize_clocklist(dev);
+
     /* Only send event if the device had been completely realized */
     if (dev->pending_deleted_event) {
         g_assert(dev->canonical_path);

include/hw/qdev-clock.h

@@ -0,0 +1,104 @@
+/*
+ * Device's clock input and output
+ *
+ * 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 QDEV_CLOCK_H
+#define QDEV_CLOCK_H
+
+#include "hw/clock.h"
+
+/**
+ * qdev_init_clock_in:
+ * @dev: the device to add an input clock to
+ * @name: the name of the clock (can't be NULL).
+ * @callback: optional callback to be called on update or NULL.
+ * @opaque: argument for the callback
+ * @returns: a pointer to the newly added clock
+ *
+ * Add an input clock to device @dev as a clock named @name.
+ * This adds a child<> property.
+ * The callback will be called with @opaque as opaque parameter.
+ */
+Clock *qdev_init_clock_in(DeviceState *dev, const char *name,
+                          ClockCallback *callback, void *opaque);
+
+/**
+ * qdev_init_clock_out:
+ * @dev: the device to add an output clock to
+ * @name: the name of the clock (can't be NULL).
+ * @returns: a pointer to the newly added clock
+ *
+ * Add an output clock to device @dev as a clock named @name.
+ * This adds a child<> property.
+ */
+Clock *qdev_init_clock_out(DeviceState *dev, const char *name);
+
+/**
+ * qdev_get_clock_in:
+ * @dev: the device which has the clock
+ * @name: the name of the clock (can't be NULL).
+ * @returns: a pointer to the clock
+ *
+ * Get the input clock @name from @dev or NULL if does not exist.
+ */
+Clock *qdev_get_clock_in(DeviceState *dev, const char *name);
+
+/**
+ * qdev_get_clock_out:
+ * @dev: the device which has the clock
+ * @name: the name of the clock (can't be NULL).
+ * @returns: a pointer to the clock
+ *
+ * Get the output clock @name from @dev or NULL if does not exist.
+ */
+Clock *qdev_get_clock_out(DeviceState *dev, const char *name);
+
+/**
+ * qdev_connect_clock_in:
+ * @dev: a device
+ * @name: the name of an input clock in @dev
+ * @source: the source clock (an output clock of another device for example)
+ *
+ * Set the source clock of input clock @name of device @dev to @source.
+ * @source period update will be propagated to @name clock.
+ */
+static inline void qdev_connect_clock_in(DeviceState *dev, const char *name,
+                                         Clock *source)
+{
+    clock_set_source(qdev_get_clock_in(dev, name), source);
+}
+
+/**
+ * qdev_alias_clock:
+ * @dev: the device which has the clock
+ * @name: the name of the clock in @dev (can't be NULL)
+ * @alias_dev: the device to add the clock
+ * @alias_name: the name of the clock in @container
+ * @returns: a pointer to the clock
+ *
+ * Add a clock @alias_name in @alias_dev which is an alias of the clock @name
+ * in @dev. The direction _in_ or _out_ will the same as the original.
+ * An alias clock must not be modified or used by @alias_dev and should
+ * typically be only only for device composition purpose.
+ */
+Clock *qdev_alias_clock(DeviceState *dev, const char *name,
+                        DeviceState *alias_dev, const char *alias_name);
+
+/**
+ * qdev_finalize_clocklist:
+ * @dev: the device being finalized
+ *
+ * Clear the clocklist from @dev. Only used internally in qdev.
+ */
+void qdev_finalize_clocklist(DeviceState *dev);
+
+#endif /* QDEV_CLOCK_H */

include/hw/qdev-core.h

@@ -149,6 +149,17 @@ struct NamedGPIOList {
     QLIST_ENTRY(NamedGPIOList) node;
 };
 
+typedef struct Clock Clock;
+typedef struct NamedClockList NamedClockList;
+
+struct NamedClockList {
+    char *name;
+    Clock *clock;
+    bool output;
+    bool alias;
+    QLIST_ENTRY(NamedClockList) node;
+};
+
 /**
  * DeviceState:
  * @realized: Indicates whether the device has been fully constructed.
@@ -171,6 +182,7 @@ struct DeviceState {
     bool allow_unplug_during_migration;
     BusState *parent_bus;
     QLIST_HEAD(, NamedGPIOList) gpios;
+    QLIST_HEAD(, NamedClockList) clocks;
     QLIST_HEAD(, BusState) child_bus;
     int num_child_bus;
     int instance_id_alias;

tests/Makefile.include

@@ -439,6 +439,7 @@ tests/test-qdev-global-props$(EXESUF): tests/test-qdev-global-props.o \
 	hw/core/fw-path-provider.o \
 	hw/core/reset.o \
 	hw/core/vmstate-if.o \
+	hw/core/clock.o hw/core/qdev-clock.o \
 	$(test-qapi-obj-y)
 tests/test-vmstate$(EXESUF): tests/test-vmstate.o \
 	migration/vmstate.o migration/vmstate-types.o migration/qemu-file.o \