hw/arm/aspeed: Unlock SCU when running kernel

The ASPEED hardware contains a lock register for the SCU that disables
any writes to the SCU when it is locked. The machine comes up with the
lock enabled, but on all known hardware u-boot will unlock it and leave
it unlocked when loading the kernel.

This means the kernel expects the SCU to be unlocked. When booting from
an emulated ROM the normal u-boot unlock path is executed. Things don't
go well when booting using the -kernel command line, as u-boot does not
run first.

Change behaviour so that when a kernel is passed to the machine, set the
reset value of the SCU to be unlocked.

Signed-off-by: Joel Stanley <joel@jms.id.au>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Message-id: 20171114122018.12204-1-joel@jms.id.au
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 9 insertions, 0 deletions

diff --git a/hw/arm/aspeed.c b/hw/arm/aspeed.c
index ab895ad..7088c90 100644
--- a/hw/arm/aspeed.c
+++ b/hw/arm/aspeed.c
@@ -186,6 +186,15 @@ static void aspeed_board_init(MachineState *machine,
                             &error_abort);
     object_property_set_int(OBJECT(&bmc->soc), cfg->num_cs, "num-cs",
                             &error_abort);
+    if (machine->kernel_filename) {
+        /*
+         * When booting with a -kernel command line there is no u-boot
+         * that runs to unlock the SCU. In this case set the default to
+         * be unlocked as the kernel expects
+         */
+        object_property_set_int(OBJECT(&bmc->soc), ASPEED_SCU_PROT_KEY,
+                                "hw-prot-key", &error_abort);
+    }
     object_property_set_bool(OBJECT(&bmc->soc), true, "realized",
                              &error_abort);