rockchip: Implement a panic handler that will reboot the system

The current Rockchip platform code retains the "common" default panic
handler which simply hangs the system (until the watchdog kicks in, if
enabled). This is usually not a great user experience.

This patch implements a Rockchip-specific panic handler that calls the
platform's reboot implementation to reset the system.

Change-Id: I4cbe09c48f1b3f86ebdfc0108c186565f9ffc119
Signed-off-by: Julius Werner <jwerner@chromium.org>

plat/rockchip/common/aarch64/plat_helpers.S

@@ -23,6 +23,7 @@
 	.globl	plat_crash_console_putc
 	.globl	plat_my_core_pos
 	.globl	plat_reset_handler
+	.globl	plat_panic_handler
 
 	/*
 	 * void plat_reset_handler(void);
@@ -107,6 +108,19 @@ func plat_crash_console_putc
 	b	console_core_putc
 endfunc plat_crash_console_putc
 
+	/* --------------------------------------------------------------------
+	 * void plat_panic_handler(void)
+	 * Call system reset function on panic. Set up an emergency stack so we
+	 * can run C functions (it only needs to last for a few calls until we
+	 * reboot anyway).
+	 * --------------------------------------------------------------------
+	 */
+func plat_panic_handler
+	msr	spsel, #0
+	bl	plat_set_my_stack
+	b	rockchip_soc_soft_reset
+endfunc plat_panic_handler
+
 	/* --------------------------------------------------------------------
 	 * void platform_cpu_warmboot (void);
 	 * cpus online or resume enterpoint