Question about the Broadcom Always On register panic handling

From: Guilherme G. Piccoli
Date: Mon Mar 21 2022 - 12:16:55 EST


Hi Brian and Florian, I'm studying the panic notifiers and found one
added by you in the commit 0b741b8234c ("soc: bcm: brcmstb: Add support
for S2/S3/S5 suspend states (ARM)". Basically, the handler is very
simple and the only thing it does is:

/* from drivers/soc/bcm/brcmstb/pm/aon_defs.h */
#define AON_REG_PANIC 0x20
#define BRCMSTB_PANIC_MAGIC 0x512E115E

/* from drivers/soc/bcm/brcmstb/pm/pm-arm.c*/
brcmstb_pm_panic_notify() {
writel_relaxed(BRCMSTB_PANIC_MAGIC, ctrl.aon_sram + AON_REG_PANIC);
}

This write happens on panic time, but I couldn't find any
information/documentation about the AON register and what effectively
happens when this write is completed. Does the SoC reboots or anything
like that?

Any information that helps me to document such panic event is very
welcome, and in case you have AON documentation, it'd be also pretty great!

Thanks in advance,


Guilherme