On Tue Feb 10, 2026 at 3:45 AM CET, John Hubbard wrote:
> + /// Check if GSP lockdown has been released after FSP Chain of Trust
> + fn gsp_lockdown_released(
> + dev: &device::Device,
> + gsp_falcon: &Falcon<Gsp>,
> + bar: &Bar0,
> + fmc_boot_params_addr: u64,
> + mbox0: &mut u32,
> + ) -> bool {
> + // Read GSP falcon mailbox0
> + *mbox0 = gsp_falcon.read_mailbox0(bar);
> +
> + // Check 1: If mbox0 has 0xbadf4100 pattern, GSP is still locked down
> + if *mbox0 != 0 && (*mbox0 & 0xffffff00) == 0xbadf4100 {
> + return false;
> + }
Hm...we could create a tiny type wrapper around this value, and do the check
with a method, such as Mbox::is_locked_down(&self).
> + // Check 2: If mbox0 has a value, check if it's an error
> + if *mbox0 != 0 {
> + let mbox1 = gsp_falcon.read_mailbox1(bar);
> +
> + let combined_addr = (u64::from(mbox1) << 32) | u64::from(*mbox0);
This could also be part of the type.
> + if combined_addr != fmc_boot_params_addr {
> + // Address doesn't match - GSP wrote an error code
> + // Return TRUE (lockdown released) with error
> + dev_dbg!(
> + dev,
> + "GSP lockdown error: mbox0={:#x}, combined_addr={:#x},
> expected={:#x}\n",
> + *mbox0,
> + combined_addr,
> + fmc_boot_params_addr
> + );
> + return true;
> + }
> + }
> +
> + // Check 3: Verify HWCFG2 RISCV_BR_PRIV_LOCKDOWN bit is clear
> + let hwcfg2 = regs::NV_PFALCON_FALCON_HWCFG2::read(bar,
> &crate::falcon::gsp::Gsp::ID);
> + !hwcfg2.riscv_br_priv_lockdown()
> + }
