Hi Alexander,
On 8/21/25 18:21, Sverdlin, Alexander wrote:
Dear Daniel, TI team,
On Fri, 2025-08-15 at 09:02 -0700, Daniel Schultz wrote:
The watchdog requires to have the MCU ESM error source enabled to
trigger a system reboot. When booting HS-SE (security enforced)
devices, the MMR registers are locked again and all write commands
are simply ignored.
Unlock the MMR registers again to successfully enable the MCU ESM
source.
I'm just curious, could you please elaborate a bit, where the registers
are being locked again if they are being unlocked by ctrl_mmr_unlock()
in board_init_f() before enable_mcu_esm_reset()?
Is it TIFS firmware?
What else could be affected?
Do we expect to leave General Purpose Control Registers unlocked
when we return from board_init_f()?
Does it mean that the whole ctrl_mmr_unlock() has to be re-done
after k3_sysfw_loader() call?
I really can't tell why those registers are locked again. I figured out
they're only locked again after loading the TIFS firmware on HS-SE
devices. So, I also assume the firmware itself locks those registers
again as part of a secure/security feature.
The A53 SPL will unlock those registers again, which will be permanent.
Only the watchdog is problematic because enable_mcu_esm_reset is
currently only called in the R5 SPL (config only enabled in the R5 SPL
defconfig).
BTW: We have seen the same behavior with the AM68A/J721S2.
- Daniel
Signed-off-by: Daniel Schultz <[email protected]>
---
arch/arm/mach-k3/am62x/am625_init.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/arch/arm/mach-k3/am62x/am625_init.c
b/arch/arm/mach-k3/am62x/am625_init.c
index a422919fab1..498bbe45b38 100644
--- a/arch/arm/mach-k3/am62x/am625_init.c
+++ b/arch/arm/mach-k3/am62x/am625_init.c
@@ -84,6 +84,9 @@ static void ctrl_mmr_unlock(void)
static __maybe_unused void enable_mcu_esm_reset(void)
{
+ /* CTRLMMR_MCU_RST registers are locked again on HS-SE devices */
+ mmr_unlock(MCU_CTRL_MMR0_BASE, 6);
+
/* Set CTRLMMR_MCU_RST_CTRL:MCU_ESM_ERROR_RST_EN_Z to '0' (low active)
*/
u32 stat = readl(CTRLMMR_MCU_RST_CTRL);
