soc/intel/common: Add low battery shutdown function

This commit adds a `do_low_battery_poweroff()` function to handle
platform power off due to critically low battery levels.

This provides a standardized way to handle low battery shutdowns across
platforms.

Additionally, the delay to the `do_low_battery_poweroff()` function,
allowing time for the low battery indicator to be displayed before
powering off. The delay is configurable through the
`PLATFORM_LOW_BATTERY_SHUTDOWN_DELAY_SEC` Kconfig option.

Finally, a low battery indicator event is logged using `elog`
before the delay.

This functionality (elog and delay) is enabled when the
`PLATFORM_HAS_LOW_BATTERY_INDICATOR` Kconfig option is selected.

BUG=b:339673254
TEST=Able to build and boot google/brox.

Change-Id: I92e9003c70c2608770972f1a302f954ebdf17bc4
Signed-off-by: Subrata Banik <subratabanik@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/86361
Reviewed-by: Karthik Ramasubramanian <kramasub@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/soc/intel/common/reset.c

@@ -3,6 +3,8 @@
 #include <arch/cache.h>
 #include <cf9_reset.h>
 #include <console/console.h>
+#include <delay.h>
+#include <elog.h>
 #include <halt.h>
 #include <reset.h>
 
@@ -21,3 +23,13 @@ void do_board_reset(void)
 {
 	full_reset();
 }
+
+void do_low_battery_poweroff(void)
+{
+	if (CONFIG(PLATFORM_HAS_LOW_BATTERY_INDICATOR)) {
+		elog_add_event_byte(ELOG_TYPE_LOW_BATTERY_INDICATOR, ELOG_FW_ISSUE_SHUTDOWN);
+		delay(CONFIG_PLATFORM_LOW_BATTERY_SHUTDOWN_DELAY_SEC);
+	}
+
+	poweroff();
+}

src/soc/intel/common/reset.h

@@ -25,4 +25,11 @@ __noreturn void global_reset(void);
  */
 efi_return_status_t fsp_get_pch_reset_status(void);
 
+/*
+ * Issue power off due to low battery
+ *
+ * Call this function to power off the platform if the battery level is critically low.
+ */
+void do_low_battery_poweroff(void);
+
 #endif	/* _INTEL_COMMON_RESET_H_ */