[PATCH v4 6/9] mac_oldworld: Add machine ID register

[BALATON Zoltan]

The G3 beige machine has a machine ID register that is accessed by the
firmware to deternine the board config. Add basic emulation of it.

Signed-off-by: BALATON Zoltan <balaton@eik.bme.hu>
---
v4: Move MermoryRegion to MachineState, use constants

 hw/ppc/mac.h          |  1 +
 hw/ppc/mac_oldworld.c | 24 ++++++++++++++++++++++++
 2 files changed, 25 insertions(+)

diff --git a/hw/ppc/mac.h b/hw/ppc/mac.h
index e04288ddfd..f4e1d5c758 100644
--- a/hw/ppc/mac.h
+++ b/hw/ppc/mac.h
@@ -64,6 +64,7 @@ typedef struct HeathrowMachineState {
     /*< private >*/
     MachineState parent;
 
+    MemoryRegion machine_id;
     PCIDevice *macio_pci;
 } HeathrowMachineState;
 
diff --git a/hw/ppc/mac_oldworld.c b/hw/ppc/mac_oldworld.c
index cb4a0f3211..53615af6b1 100644
--- a/hw/ppc/mac_oldworld.c
+++ b/hw/ppc/mac_oldworld.c
@@ -52,6 +52,9 @@
 
 #define MAX_IDE_BUS 2
 #define CFG_ADDR 0xf0000510
+#define MACHINE_ID_ADDR 0xff000004
+#define MACHINE_ID_VAL 0x3d8c
+
 #define TBFREQ 16600000UL
 #define CLOCKFREQ 266000000UL
 #define BUSFREQ 66000000UL
@@ -89,6 +92,22 @@ static void ppc_heathrow_cpu_reset(void *opaque)
     cpu_reset(CPU(cpu));
 }
 
+static uint64_t machine_id_read(void *opaque, hwaddr addr, unsigned size)
+{
+    return (addr == 0 && size == 2 ? MACHINE_ID_VAL : 0);
+}
+
+static void machine_id_write(void *opaque, hwaddr addr,
+                             uint64_t val, unsigned size)
+{
+    return;
+}
+
+const MemoryRegionOps machine_id_reg_ops = {
+    .read = machine_id_read,
+    .write = machine_id_write,
+};
+
 static void ppc_heathrow_init(MachineState *machine)
 {
     HeathrowMachineState *hm = HEATHROW_MACHINE(machine);
@@ -242,6 +261,11 @@ static void ppc_heathrow_init(MachineState *machine)
         }
     }
 
+    memory_region_init_io(&hm->machine_id, OBJECT(machine),
+                          &machine_id_reg_ops, NULL, "machine_id", 2);
+    memory_region_add_subregion(get_system_memory(), MACHINE_ID_ADDR,
+                                &hm->machine_id);
+
     /* XXX: we register only 1 output pin for heathrow PIC */
     pic_dev = qdev_create(NULL, TYPE_HEATHROW);
     qdev_init_nofail(pic_dev);
-- 
2.21.3