isa: add a isa_vga_init() function

This function create a ISA VGA device according to the value of
vga_interface_type. It returns a ISADevice (and not a DeviceState).
Signed-off-by: NAurelien Jarno <aurelien@aurel32.net>

hw/isa-bus.c

@@ -19,6 +19,7 @@
 #include "hw.h"
 #include "monitor.h"
 #include "sysbus.h"
+#include "sysemu.h"
 #include "isa.h"
 #include "exec-memory.h"
 
@@ -166,6 +167,25 @@ ISADevice *isa_create_simple(ISABus *bus, const char *name)
     return dev;
 }
 
+ISADevice *isa_vga_init(ISABus *bus)
+{
+    switch (vga_interface_type) {
+    case VGA_CIRRUS:
+        return isa_create_simple(bus, "isa-cirrus-vga");
+    case VGA_QXL:
+        fprintf(stderr, "%s: qxl: no PCI bus\n", __func__);
+        return NULL;
+    case VGA_STD:
+        return isa_create_simple(bus, "isa-vga");
+    case VGA_VMWARE:
+        fprintf(stderr, "%s: vmware_vga: no PCI bus\n", __func__);
+        return NULL;
+    case VGA_NONE:
+    default:
+        return NULL;
+    }
+}
+
 static void isabus_dev_print(Monitor *mon, DeviceState *dev, int indent)
 {
     ISADevice *d = ISA_DEVICE(dev);

hw/isa.h

@@ -47,6 +47,8 @@ ISADevice *isa_create(ISABus *bus, const char *name);
 ISADevice *isa_try_create(ISABus *bus, const char *name);
 ISADevice *isa_create_simple(ISABus *bus, const char *name);
 
+ISADevice *isa_vga_init(ISABus *bus);
+
 /**
  * isa_register_ioport: Install an I/O port region on the ISA bus.
  *