Add default crash console code to hook up to new console API

This patch expands the weak stubs for the plat_crash_console_xxx
functions in common platform code to use the new console API for crash
output. This should make crash console output "just work" for most cases
without the need for the platform to explicitly set up a crash console.
For cases where the normal console framework doesn't work (e.g. very
early crashes, before the platform can register any consoles), platforms
are still able to override the functions just like before.

This feature requires the MULTI_CONSOLE_API compile-time flag to work.
For builds which don't have it set, this patch has no practical effect.

Change-Id: I80dd161cb43f9db59a0bad2dae33c6560cfac584
Signed-off-by: Julius Werner <jwerner@chromium.org>

1 files changed, 53 insertions, 7 deletions

diff --git a/plat/common/aarch64/platform_helpers.S b/plat/common/aarch64/platform_helpers.S
index 797a93639..852675277 100644
--- a/plat/common/aarch64/platform_helpers.S
+++ b/plat/common/aarch64/platform_helpers.S
@@ -6,6 +6,7 @@
 
 #include <arch.h>
 #include <asm_macros.S>
+#include <console.h>
 #include <platform_def.h>
 
 	.weak	plat_report_exception
@@ -56,33 +57,78 @@ func plat_report_exception
 	ret
 endfunc plat_report_exception
 
+#if MULTI_CONSOLE_API
 	/* -----------------------------------------------------
-	 * Placeholder function which should be redefined by
-	 * each platform.
+	 * int plat_crash_console_init(void)
+	 * Use normal console by default. Switch it to crash
+	 * mode so serial consoles become active again.
+	 * NOTE: This default implementation will only work for
+	 * crashes that occur after a normal console (marked
+	 * valid for the crash state) has been registered with
+	 * the console framework. To debug crashes that occur
+	 * earlier, the platform has to override these functions
+	 * with an implementation that initializes a console
+	 * driver with hardcoded parameters. See
+	 * docs/porting-guide.rst for more information.
 	 * -----------------------------------------------------
 	 */
 func plat_crash_console_init
+#if defined(IMAGE_BL1)
+	/*
+	 * BL1 code can possibly crash so early that the data segment is not yet
+	 * accessible. Don't risk undefined behavior by trying to run the normal
+	 * console framework. Platforms that want to debug BL1 will need to
+	 * override this with custom functions that can run from registers only.
+	 */
 	mov	x0, #0
 	ret
+#else	/* IMAGE_BL1 */
+	mov	x3, x30
+	mov	x0, #CONSOLE_FLAG_CRASH
+	bl	console_switch_state
+	mov	x0, #1
+	ret	x3
+#endif
 endfunc plat_crash_console_init
 
 	/* -----------------------------------------------------
-	 * Placeholder function which should be redefined by
-	 * each platform.
+	 * void plat_crash_console_putc(int character)
+	 * Output through the normal console by default.
 	 * -----------------------------------------------------
 	 */
 func plat_crash_console_putc
-	ret
+	b	console_putc
 endfunc plat_crash_console_putc
 
 	/* -----------------------------------------------------
-	 * Placeholder function which should be redefined by
-	 * each platform.
+	 * void plat_crash_console_flush(void)
+	 * Flush normal console by default.
+	 * -----------------------------------------------------
+	 */
+func plat_crash_console_flush
+	b	console_flush
+endfunc plat_crash_console_flush
+
+#else	/* MULTI_CONSOLE_API */
+
+	/* -----------------------------------------------------
+	 * In the old API these are all no-op stubs that need to
+	 * be overridden by the platform to be useful.
 	 * -----------------------------------------------------
 	 */
+func plat_crash_console_init
+	mov	x0, #0
+	ret
+endfunc plat_crash_console_init
+
+func plat_crash_console_putc
+	ret
+endfunc plat_crash_console_putc
+
 func plat_crash_console_flush
 	ret
 endfunc plat_crash_console_flush
+#endif
 
 	/* -----------------------------------------------------
 	 * Placeholder function which should be redefined by