hw/core/register: remove the REGISTER device type

The REGISTER class (RegisterInfo struct) is currently a QOM type
inheriting from DEVICE. This class has no real purpose:
   - the qdev API is not used,
   - according to the comment preceding it, the object_initialize call
     is here to zero-initialize the struct. However all the effective
     struct attributes are then initialized explicitly.
   - the object is never parented.

This commits drops the REGISTER QOM type completely, leaving the
RegisterInfo struct as a bare C struct.

The register_register_types function is left empty here because it is
reused in the next commit.

Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Francisco Iglesias <francisco.iglesias@amd.com>
Reviewed-by: Edgar E. Iglesias <edgar.iglesias@amd.com>
Signed-off-by: Luc Michel <luc.michel@amd.com>
Message-ID: <20251017161809.235740-2-luc.michel@amd.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>

hw/core/register.c

@@ -258,9 +258,6 @@ static RegisterInfoArray *register_init_block(DeviceState *owner,
         int index = rae[i].addr / data_size;
         RegisterInfo *r = &ri[index];
 
-        /* Init the register, this will zero it. */
-        object_initialize((void *)r, sizeof(*r), TYPE_REGISTER);
-
         /* Set the properties of the register */
         r->data = data + data_size * index;
         r->data_size = data_size;
@@ -318,24 +315,9 @@ void register_finalize_block(RegisterInfoArray *r_array)
     g_free(r_array);
 }
 
-static void register_class_init(ObjectClass *oc, const void *data)
-{
-    DeviceClass *dc = DEVICE_CLASS(oc);
-
-    /* Reason: needs to be wired up to work */
-    dc->user_creatable = false;
-}
-
-static const TypeInfo register_info = {
-    .name  = TYPE_REGISTER,
-    .parent = TYPE_DEVICE,
-    .class_init = register_class_init,
-    .instance_size = sizeof(RegisterInfo),
-};
 
 static void register_register_types(void)
 {
-    type_register_static(&register_info);
 }
 
 type_init(register_register_types)

hw/net/can/xlnx-versal-canfd.c

@@ -1868,8 +1868,6 @@ static int canfd_populate_regarray(XlnxVersalCANFDState *s,
         int index = rae[i].addr / 4;
         RegisterInfo *r = &s->reg_info[index];
 
-        object_initialize(r, sizeof(*r), TYPE_REGISTER);
-
         *r = (RegisterInfo) {
             .data = &s->regs[index],
             .data_size = sizeof(uint32_t),

include/hw/register.h

@@ -75,10 +75,6 @@ struct RegisterAccessInfo {
  */
 
 struct RegisterInfo {
-    /* <private> */
-    DeviceState parent_obj;
-
-    /* <public> */
     void *data;
     int data_size;
 
@@ -87,9 +83,6 @@ struct RegisterInfo {
     void *opaque;
 };
 
-#define TYPE_REGISTER "qemu-register"
-DECLARE_INSTANCE_CHECKER(RegisterInfo, REGISTER,
-                         TYPE_REGISTER)
 
 /**
  * This structure is used to group all of the individual registers which are