Add an isa device for SGA

This patch adds a dummy legacy ISA device whose responsibility is to
deploy sgabios, an option rom for a serial graphics adapter.
The proposal is that this device is always-on when -nographics,
but can otherwise be enable in any setup when -device sga is used.

[v2: suggestions on qdev by Markus ]
[v3: cleanups and documentation, per list suggestions ]

Signed-off-by: Glauber Costa <glommer@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

Makefile.target

@@ -231,7 +231,7 @@ obj-$(CONFIG_IVSHMEM) += ivshmem.o
 # Hardware support
 obj-i386-y += vga.o
 obj-i386-y += mc146818rtc.o i8259.o pc.o
-obj-i386-y += cirrus_vga.o apic.o ioapic.o piix_pci.o
+obj-i386-y += cirrus_vga.o sga.o apic.o ioapic.o piix_pci.o
 obj-i386-y += vmport.o
 obj-i386-y += device-hotplug.o pci-hotplug.o smbios.o wdt_ib700.o
 obj-i386-y += debugcon.o multiboot.o

hw/pc.c

@@ -1070,6 +1070,15 @@ void pc_vga_init(PCIBus *pci_bus)
             isa_vga_init();
         }
     }
+
+    /*
+     * sga does not suppress normal vga output. So a machine can have both a
+     * vga card and sga manually enabled. Output will be seen on both.
+     * For nographic case, sga is enabled at all times
+     */
+    if (display_type == DT_NOGRAPHIC) {
+        isa_create_simple("sga");
+    }
 }
 
 static void cpu_request_exit(void *opaque, int irq, int level)

hw/sga.c

@@ -0,0 +1,56 @@
+/*
+ * QEMU dummy ISA device for loading sgabios option rom.
+ *
+ * Copyright (c) 2011 Glauber Costa, Red Hat Inc.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ *
+ * sgabios code originally available at code.google.com/p/sgabios
+ *
+ */
+#include "pci.h"
+#include "pc.h"
+#include "loader.h"
+#include "sysemu.h"
+
+#define SGABIOS_FILENAME "sgabios.bin"
+
+typedef struct ISAGAState {
+    ISADevice dev;
+} ISASGAState;
+
+static int isa_cirrus_vga_initfn(ISADevice *dev)
+{
+    rom_add_vga(SGABIOS_FILENAME);
+    return 0;
+}
+
+static ISADeviceInfo sga_info = {
+    .qdev.name    = "sga",
+    .qdev.desc    = "Serial Graphics Adapter",
+    .qdev.size    = sizeof(ISASGAState),
+    .init         = isa_cirrus_vga_initfn,
+};
+
+static void sga_register(void)
+{
+      isa_qdev_register(&sga_info);
+}
+
+device_init(sga_register);