[PATCH v4 03/21] hw/arm/ast27x0: Start SSP in powered-off state to match hardware behavior

[Jamin Lin <jamin_lin@aspeedtech.com>]

In the previous design, both the PSP and SSP were started together during
SoC initialization. However, on real hardware, the SSP begins in a powered-off
state. The typical boot sequence involves the PSP powering up first, loading
the SSP firmware binary into shared memory via DRAM remap, and then releasing
the SSP reset and enabling it through SCU control registers.

To more accurately model this behavior in QEMU, this commit sets the
"start-powered-off" property for the SSP's ARMv7M core. This change ensures
the SSP remains off until explicitly enabled via the SCU, simulating the
real-world flow where the PSP controls SSP boot through SCU interaction.

Signed-off-by: Jamin Lin <jamin_lin@aspeedtech.com>
---
 hw/arm/aspeed_ast27x0-ssp.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/hw/arm/aspeed_ast27x0-ssp.c b/hw/arm/aspeed_ast27x0-ssp.c
index 9a2079668b..edfcf1badb 100644
--- a/hw/arm/aspeed_ast27x0-ssp.c
+++ b/hw/arm/aspeed_ast27x0-ssp.c
@@ -166,6 +166,13 @@ static void aspeed_soc_ast27x0ssp_realize(DeviceState *dev_soc, Error **errp)
     qdev_connect_clock_in(armv7m, "cpuclk", s->sysclk);
     object_property_set_link(OBJECT(&a->armv7m), "memory",
                              OBJECT(s->memory), &error_abort);
+    /*
+     * The SSP starts in a powered-down state and can be powered up
+     * by setting the SSP Control Register through the SCU
+     * (System Control Unit)
+     */
+    object_property_set_bool(OBJECT(&a->armv7m), "start-powered-off", true,
+                             &error_abort);
     sysbus_realize(SYS_BUS_DEVICE(&a->armv7m), &error_abort);
 
     /* SDRAM */
-- 
2.43.0