hw/timer/cmsdk-apb-timer: Add Clock input

As the first step in converting the CMSDK_APB_TIMER device to the
Clock framework, add a Clock input.  For the moment we do nothing
with this clock; we will change the behaviour from using the pclk-frq
property to using the Clock once all the users of this device have
been converted to wire up the Clock.

Since the device doesn't already have a doc comment for its "QEMU
interface", we add one including the new Clock.

This is a migration compatibility break for machines mps2-an505,
mps2-an521, musca-a, musca-b1.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Luc Michel <luc@lmichel.fr>
Tested-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-id: 20210128114145.20536-8-peter.maydell@linaro.org
Message-id: 20210121190622.22000-8-peter.maydell@linaro.org

hw/timer/cmsdk-apb-timer.c

@@ -35,6 +35,7 @@
 #include "hw/sysbus.h"
 #include "hw/irq.h"
 #include "hw/registerfields.h"
+#include "hw/qdev-clock.h"
 #include "hw/timer/cmsdk-apb-timer.h"
 #include "migration/vmstate.h"
 
@@ -212,6 +213,7 @@ static void cmsdk_apb_timer_init(Object *obj)
                           s, "cmsdk-apb-timer", 0x1000);
     sysbus_init_mmio(sbd, &s->iomem);
     sysbus_init_irq(sbd, &s->timerint);
+    s->pclk = qdev_init_clock_in(DEVICE(s), "pclk", NULL, NULL);
 }
 
 static void cmsdk_apb_timer_realize(DeviceState *dev, Error **errp)
@@ -236,10 +238,11 @@ static void cmsdk_apb_timer_realize(DeviceState *dev, Error **errp)
 
 static const VMStateDescription cmsdk_apb_timer_vmstate = {
     .name = "cmsdk-apb-timer",
-    .version_id = 1,
-    .minimum_version_id = 1,
+    .version_id = 2,
+    .minimum_version_id = 2,
     .fields = (VMStateField[]) {
         VMSTATE_PTIMER(timer, CMSDKAPBTimer),
+        VMSTATE_CLOCK(pclk, CMSDKAPBTimer),
         VMSTATE_UINT32(ctrl, CMSDKAPBTimer),
         VMSTATE_UINT32(value, CMSDKAPBTimer),
         VMSTATE_UINT32(reload, CMSDKAPBTimer),

include/hw/timer/cmsdk-apb-timer.h

@@ -15,11 +15,19 @@
 #include "hw/qdev-properties.h"
 #include "hw/sysbus.h"
 #include "hw/ptimer.h"
+#include "hw/clock.h"
 #include "qom/object.h"
 
 #define TYPE_CMSDK_APB_TIMER "cmsdk-apb-timer"
 OBJECT_DECLARE_SIMPLE_TYPE(CMSDKAPBTimer, CMSDK_APB_TIMER)
 
+/*
+ * QEMU interface:
+ *  + QOM property "pclk-frq": frequency at which the timer is clocked
+ *  + Clock input "pclk": clock for the timer
+ *  + sysbus MMIO region 0: the register bank
+ *  + sysbus IRQ 0: timer interrupt TIMERINT
+ */
 struct CMSDKAPBTimer {
     /*< private >*/
     SysBusDevice parent_obj;
@@ -29,6 +37,7 @@ struct CMSDKAPBTimer {
     qemu_irq timerint;
     uint32_t pclk_frq;
     struct ptimer_state *timer;
+    Clock *pclk;
 
     uint32_t ctrl;
     uint32_t value;