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

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 specify the board serial
number. When not given, the default serial number 1 is used.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Palmer Dabbelt <palmerdabbelt@google.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-Id: <1573916930-19068-1-git-send-email-bmeng.cn@gmail.com>
[ Changed by AF:
 - Use the SoC's serial property to pass the info to the SoC
 - Fixup commit title
 - Rebase on file restructuring
]
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>

hw/riscv/sifive_u.c

@@ -34,6 +34,7 @@
 #include "qemu/log.h"
 #include "qemu/error-report.h"
 #include "qapi/error.h"
+#include "qapi/visitor.h"
 #include "hw/boards.h"
 #include "hw/loader.h"
 #include "hw/sysbus.h"
@@ -326,6 +327,8 @@ static void sifive_u_machine_init(MachineState *machine)
     object_initialize_child(OBJECT(machine), "soc", &s->soc,
                             sizeof(s->soc), TYPE_RISCV_U_SOC,
                             &error_abort, NULL);
+    object_property_set_uint(OBJECT(&s->soc), s->serial, "serial",
+                            &error_abort);
     object_property_set_bool(OBJECT(&s->soc), true, "realized",
                             &error_abort);
 
@@ -417,6 +420,18 @@ static void sifive_u_machine_set_start_in_flash(Object *obj, bool value, Error *
     s->start_in_flash = value;
 }
 
+static void sifive_u_machine_get_serial(Object *obj, Visitor *v, const char *name,
+                                void *opaque, Error **errp)
+{
+    visit_type_uint32(v, name, (uint32_t *)opaque, errp);
+}
+
+static void sifive_u_machine_set_serial(Object *obj, Visitor *v, const char *name,
+                                void *opaque, Error **errp)
+{
+    visit_type_uint32(v, name, (uint32_t *)opaque, errp);
+}
+
 static void sifive_u_machine_instance_init(Object *obj)
 {
     SiFiveUState *s = RISCV_U_MACHINE(obj);
@@ -428,6 +443,11 @@ static void sifive_u_machine_instance_init(Object *obj)
                                     "Set on to tell QEMU's ROM to jump to "
                                     "flash. Otherwise QEMU will jump to DRAM",
                                     NULL);
+
+    s->serial = OTP_SERIAL;
+    object_property_add(obj, "serial", "uint32", sifive_u_machine_get_serial,
+                        sifive_u_machine_set_serial, NULL, &s->serial, NULL);
+    object_property_set_description(obj, "serial", "Board serial number", NULL);
 }
 
 static void sifive_u_machine_class_init(ObjectClass *oc, void *data)

include/hw/riscv/sifive_u.h

@@ -61,6 +61,7 @@ typedef struct SiFiveUState {
     int fdt_size;
 
     bool start_in_flash;
+    uint32_t serial;
 } SiFiveUState;
 
 enum {