Merge tag 'pull-target-arm-20240227-1' of https://git.linaro.org/people/pmaydell/qemu-arm into staging

target-arm queue:
 * Handle atomic updates of page tables entries in MMIO during PTW
 * Advertise Cortex-A53 erratum #843419 fix via REVIDR
 * MAINTAINERS: Cover hw/ide/ahci-allwinner.c with AllWinner A10 machine
 * misc: m48t59: replace qemu_system_reset_request() call with watchdog_perform_action()
 * misc: pxa2xx_timer: replace qemu_system_reset_request() call with watchdog_perform_action()
 * xlnx-versal-ospi: disable reentrancy detection for iomem_dac
 * sbsa-ref: Simplify init since PCIe is always enabled
 * stm32l4x5: Use TYPE_OR_IRQ when connecting STM32L4x5 EXTI fan-in IRQs
 * pl031: Update last RTCLR value on write in case it's read back
 * block: m25p80: Add support of mt35xu02gbba
 * xlnx-versal-virt: Add machine property ospi-flash
 * reset: refactor system reset to be three-phase aware
 * new board model raspi4b

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# gpg:                 aka "Peter Maydell <pmaydell@chiark.greenend.org.uk>" [ultimate]
# gpg:                 aka "Peter Maydell <peter@archaic.org.uk>" [ultimate]
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* tag 'pull-target-arm-20240227-1' of https://git.linaro.org/people/pmaydell/qemu-arm: (36 commits)
  docs/system/arm: Add RPi4B to raspi.rst
  hw/misc/bcm2835_property: Add missed BCM2835 properties
  tests/avocado/boot_linux_console.py: Add Rpi4b boot tests
  hw/arm/bcm2838_peripherals: Add clock_isp stub
  hw/arm: Add memory region for BCM2837 RPiVid ASB
  hw/arm/raspi4b: Temporarily disable unimplemented rpi4b devices
  hw/arm: Introduce Raspberry PI 4 machine
  hw/arm: Add GPIO and SD to BCM2838 periph
  hw/gpio: Connect SD controller to BCM2838 GPIO
  hw/gpio: Implement BCM2838 GPIO functionality
  hw/gpio: Add BCM2838 GPIO stub
  hw/arm/bcm2838: Add GIC-400 to BCM2838 SoC
  hw/arm: Introduce BCM2838 SoC
  hw/arm/raspi: Split out raspi machine common part
  hw/arm/bcm2853_peripherals: Split out common part of peripherals
  hw/arm/bcm2836: Split out common part of BCM283X classes
  docs/devel/reset: Update to discuss system reset
  hw/core/machine: Use qemu_register_resettable for sysbus reset
  hw/core/reset: Implement qemu_register_reset via qemu_register_resettable
  hw/core/reset: Add qemu_{register, unregister}_resettable()
  ...

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

2 files changed, 71 insertions, 7 deletions

diff --git a/docs/devel/qom.rst b/docs/devel/qom.rst
index 9918fac7f2..0889ca949c 100644
--- a/docs/devel/qom.rst
+++ b/docs/devel/qom.rst
@@ -348,12 +348,14 @@ used. This does the same as OBJECT_DECLARE_SIMPLE_TYPE(), but without
 the 'struct MyDeviceClass' definition.
 
 To implement the type, the OBJECT_DEFINE macro family is available.
-In the simple case the OBJECT_DEFINE_TYPE macro is suitable:
+For the simplest case of a leaf class which doesn't need any of its
+own virtual functions (i.e. which was declared with OBJECT_DECLARE_SIMPLE_TYPE)
+the OBJECT_DEFINE_SIMPLE_TYPE macro is suitable:
 
 .. code-block:: c
    :caption: Defining a simple type
 
-   OBJECT_DEFINE_TYPE(MyDevice, my_device, MY_DEVICE, DEVICE)
+   OBJECT_DEFINE_SIMPLE_TYPE(MyDevice, my_device, MY_DEVICE, DEVICE)
 
 This is equivalent to the following:
 
@@ -370,7 +372,6 @@ This is equivalent to the following:
        .instance_size = sizeof(MyDevice),
        .instance_init = my_device_init,
        .instance_finalize = my_device_finalize,
-       .class_size = sizeof(MyDeviceClass),
        .class_init = my_device_class_init,
    };
 
@@ -385,13 +386,36 @@ This is sufficient to get the type registered with the type
 system, and the three standard methods now need to be implemented
 along with any other logic required for the type.
 
+If the class needs its own virtual methods, or has some other
+per-class state it needs to store in its own class struct,
+then you can use the OBJECT_DEFINE_TYPE macro. This does the
+same thing as OBJECT_DEFINE_SIMPLE_TYPE, but it also sets the
+class_size of the type to the size of the class struct.
+
+.. code-block:: c
+   :caption: Defining a type which needs a class struct
+
+   OBJECT_DEFINE_TYPE(MyDevice, my_device, MY_DEVICE, DEVICE)
+
 If the type needs to implement one or more interfaces, then the
-OBJECT_DEFINE_TYPE_WITH_INTERFACES() macro can be used instead.
-This accepts an array of interface type names.
+OBJECT_DEFINE_SIMPLE_TYPE_WITH_INTERFACES() and
+OBJECT_DEFINE_TYPE_WITH_INTERFACES() macros can be used instead.
+These accept an array of interface type names. The difference between
+them is that the former is for simple leaf classes that don't need
+a class struct, and the latter is for when you will be defining
+a class struct.
 
 .. code-block:: c
    :caption: Defining a simple type implementing interfaces
 
+   OBJECT_DEFINE_SIMPLE_TYPE_WITH_INTERFACES(MyDevice, my_device,
+                                             MY_DEVICE, DEVICE,
+                                             { TYPE_USER_CREATABLE },
+                                             { NULL })
+
+.. code-block:: c
+   :caption: Defining a type implementing interfaces
+
    OBJECT_DEFINE_TYPE_WITH_INTERFACES(MyDevice, my_device,
                                       MY_DEVICE, DEVICE,
                                       { TYPE_USER_CREATABLE },
diff --git a/docs/devel/reset.rst b/docs/devel/reset.rst
index d4e79718ba..2ea85e7779 100644
--- a/docs/devel/reset.rst
+++ b/docs/devel/reset.rst
@@ -11,8 +11,8 @@ whole group can be reset consistently. Each individual member object does not
 have to care about others; in particular, problems of order (which object is
 reset first) are addressed.
 
-As of now DeviceClass and BusClass implement this interface.
-
+The main object types which implement this interface are DeviceClass
+and BusClass.
 
 Triggering reset
 ----------------
@@ -288,3 +288,43 @@ There is currently 2 cases where this function is used:
 2. *hot bus change*; it means an existing live device is added, moved or
    removed in the bus hierarchy. At the moment, it occurs only in the raspi
    machines for changing the sdbus used by sd card.
+
+Reset of the complete system
+----------------------------
+
+Reset of the complete system is a little complicated. The typical
+flow is:
+
+1. Code which wishes to reset the entire system does so by calling
+   ``qemu_system_reset_request()``. This schedules a reset, but the
+   reset will happen asynchronously after the function returns.
+   That makes this safe to call from, for example, device models.
+
+2. The function which is called to make the reset happen is
+   ``qemu_system_reset()``. Generally only core system code should
+   call this directly.
+
+3. ``qemu_system_reset()`` calls the ``MachineClass::reset`` method of
+   the current machine, if it has one. That method must call
+   ``qemu_devices_reset()``. If the machine has no reset method,
+   ``qemu_system_reset()`` calls ``qemu_devices_reset()`` directly.
+
+4. ``qemu_devices_reset()`` performs a reset of the system, using
+   the three-phase mechanism listed above. It resets all objects
+   that were registered with it using ``qemu_register_resettable()``.
+   It also calls all the functions registered with it using
+   ``qemu_register_reset()``. Those functions are called during the
+   "hold" phase of this reset.
+
+5. The most important object that this reset resets is the
+   'sysbus' bus. The sysbus bus is the root of the qbus tree. This
+   means that all devices on the sysbus are reset, and all their
+   child buses, and all the devices on those child buses.
+
+6. Devices which are not on the qbus tree are *not* automatically
+   reset! (The most obvious example of this is CPU objects, but
+   anything that directly inherits from ``TYPE_OBJECT`` or ``TYPE_DEVICE``
+   rather than from ``TYPE_SYS_BUS_DEVICE`` or some other plugs-into-a-bus
+   type will be in this category.) You need to therefore arrange for these
+   to be reset in some other way (e.g. using ``qemu_register_resettable()``
+   or ``qemu_register_reset()``).