qdev-clock: introduce an init array to ease the device construction

Introduce a function and macro helpers to setup several clocks
in a device from a static array description.

An element of the array describes the clock (name and direction) as
well as the related callback and an optional offset to store the
created object pointer in the device state structure.

The array must be terminated by a special element QDEV_CLOCK_END.

This is based on the original work of Frederic Konrad.

Signed-off-by: Damien Hedde <damien.hedde@greensocs.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
Message-id: 20200406135251.157596-5-damien.hedde@greensocs.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

hw/core/qdev-clock.c

@@ -116,6 +116,23 @@ Clock *qdev_init_clock_in(DeviceState *dev, const char *name,
     return ncl->clock;
 }
 
+void qdev_init_clocks(DeviceState *dev, const ClockPortInitArray clocks)
+{
+    const struct ClockPortInitElem *elem;
+
+    for (elem = &clocks[0]; elem->name != NULL; elem++) {
+        Clock **clkp;
+        /* offset cannot be inside the DeviceState part */
+        assert(elem->offset > sizeof(DeviceState));
+        clkp = (Clock **)(((void *) dev) + elem->offset);
+        if (elem->is_output) {
+            *clkp = qdev_init_clock_out(dev, elem->name);
+        } else {
+            *clkp = qdev_init_clock_in(dev, elem->name, elem->callback, dev);
+        }
+    }
+}
+
 static NamedClockList *qdev_get_clocklist(DeviceState *dev, const char *name)
 {
     NamedClockList *ncl;

include/hw/qdev-clock.h

@@ -101,4 +101,59 @@ Clock *qdev_alias_clock(DeviceState *dev, const char *name,
  */
 void qdev_finalize_clocklist(DeviceState *dev);
 
+/**
+ * ClockPortInitElem:
+ * @name: name of the clock (can't be NULL)
+ * @output: indicates whether the clock is input or output
+ * @callback: for inputs, optional callback to be called on clock's update
+ * with device as opaque
+ * @offset: optional offset to store the ClockIn or ClockOut pointer in device
+ * state structure (0 means unused)
+ */
+struct ClockPortInitElem {
+    const char *name;
+    bool is_output;
+    ClockCallback *callback;
+    size_t offset;
+};
+
+#define clock_offset_value(devstate, field) \
+    (offsetof(devstate, field) + \
+     type_check(Clock *, typeof_field(devstate, field)))
+
+#define QDEV_CLOCK(out_not_in, devstate, field, cb) { \
+    .name = (stringify(field)), \
+    .is_output = out_not_in, \
+    .callback = cb, \
+    .offset = clock_offset_value(devstate, field), \
+}
+
+/**
+ * QDEV_CLOCK_(IN|OUT):
+ * @devstate: structure type. @dev argument of qdev_init_clocks below must be
+ * a pointer to that same type.
+ * @field: a field in @_devstate (must be Clock*)
+ * @callback: (for input only) callback (or NULL) to be called with the device
+ * state as argument
+ *
+ * The name of the clock will be derived from @field
+ */
+#define QDEV_CLOCK_IN(devstate, field, callback) \
+    QDEV_CLOCK(false, devstate, field, callback)
+
+#define QDEV_CLOCK_OUT(devstate, field) \
+    QDEV_CLOCK(true, devstate, field, NULL)
+
+#define QDEV_CLOCK_END { .name = NULL }
+
+typedef struct ClockPortInitElem ClockPortInitArray[];
+
+/**
+ * qdev_init_clocks:
+ * @dev: the device to add clocks to
+ * @clocks: a QDEV_CLOCK_END-terminated array which contains the
+ * clocks information.
+ */
+void qdev_init_clocks(DeviceState *dev, const ClockPortInitArray clocks);
+
 #endif /* QDEV_CLOCK_H */