riscv/sifive_u: Add a serial property to the sifive_u SoC

At present the board serial number is hard-coded to 1, and passed
to OTP model during initialization. Firmware (FSBL, U-Boot) uses
the serial number to generate a unique MAC address for the on-chip
ethernet controller. When multiple QEMU 'sifive_u' instances are
created and connected to the same subnet, they all have the same
MAC address hence it creates a unusable network.

A new "serial" property is introduced to the sifive_u SoC to specify
the board serial number. When not given, the default serial number
1 is used.

Suggested-by: Bin Meng <bmeng.cn@gmail.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Tested-by: Bin Meng <bmeng.cn@gmail.com>

hw/riscv/sifive_u.c

@@ -491,7 +491,6 @@ static void riscv_sifive_u_soc_init(Object *obj)
                           TYPE_SIFIVE_U_PRCI);
     sysbus_init_child_obj(obj, "otp", &s->otp, sizeof(s->otp),
                           TYPE_SIFIVE_U_OTP);
-    qdev_prop_set_uint32(DEVICE(&s->otp), "serial", OTP_SERIAL);
     sysbus_init_child_obj(obj, "gem", &s->gem, sizeof(s->gem),
                           TYPE_CADENCE_GEM);
 }
@@ -584,6 +583,7 @@ static void riscv_sifive_u_soc_realize(DeviceState *dev, Error **errp)
     object_property_set_bool(OBJECT(&s->prci), true, "realized", &err);
     sysbus_mmio_map(SYS_BUS_DEVICE(&s->prci), 0, memmap[SIFIVE_U_PRCI].base);
 
+    qdev_prop_set_uint32(DEVICE(&s->otp), "serial", s->serial);
     object_property_set_bool(OBJECT(&s->otp), true, "realized", &err);
     sysbus_mmio_map(SYS_BUS_DEVICE(&s->otp), 0, memmap[SIFIVE_U_OTP].base);
 
@@ -610,10 +610,16 @@ static void riscv_sifive_u_soc_realize(DeviceState *dev, Error **errp)
         memmap[SIFIVE_U_GEM_MGMT].base, memmap[SIFIVE_U_GEM_MGMT].size);
 }
 
+static Property riscv_sifive_u_soc_props[] = {
+    DEFINE_PROP_UINT32("serial", SiFiveUSoCState, serial, OTP_SERIAL),
+    DEFINE_PROP_END_OF_LIST()
+};
+
 static void riscv_sifive_u_soc_class_init(ObjectClass *oc, void *data)
 {
     DeviceClass *dc = DEVICE_CLASS(oc);
 
+    device_class_set_props(dc, riscv_sifive_u_soc_props);
     dc->realize = riscv_sifive_u_soc_realize;
     /* Reason: Uses serial_hds in realize function, thus can't be used twice */
     dc->user_creatable = false;

include/hw/riscv/sifive_u.h

@@ -42,6 +42,8 @@ typedef struct SiFiveUSoCState {
     SiFiveUPRCIState prci;
     SiFiveUOTPState otp;
     CadenceGEMState gem;
+
+    uint32_t serial;
 } SiFiveUSoCState;
 
 #define TYPE_RISCV_U_MACHINE MACHINE_TYPE_NAME("sifive_u")