console/flashsconsole: Add spi flash console for debugging

If CONSOLE_SPI_FLASH config is enabled, we write the cbmem
messages to the 'CONSOLE' area in FMAP which allows us to grab the
log when we read the flash.

This is useful when you don't have usb debugging, and
UART lines are hard to find. Since a failure to boot would
require a hardware flasher anyways, we can get the log
at the same time.

This feature should only be used when no alternative is
found and only when we can't boot the system, because
excessive writes to the flash is not recommended.

This has been tested on purism/librem13 v2 and librem 15 v3 which
run Intel Skylake hardware. It has not been tested on other archs
or with a driver other than the fast_spi.

Change-Id: I74a297b94f6881d8c27cbe5168f161d8331c3df3
Signed-off-by: Youness Alaoui <youness.alaoui@puri.sm>
Reviewed-on: https://review.coreboot.org/19849
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>
Reviewed-by: Philippe Mathieu-Daudé <philippe.mathieu.daude@gmail.com>

1 files changed, 45 insertions, 0 deletions

diff --git a/src/include/console/flash.h b/src/include/console/flash.h
new file mode 100644
index 0000000000..07bc724b19
--- /dev/null
+++ b/src/include/console/flash.h
@@ -0,0 +1,45 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright 2015 Google Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#ifndef CONSOLE_FLASH_H
+#define CONSOLE_FLASH_H 1
+
+#include <rules.h>
+#include <stdint.h>
+
+void flashconsole_init(void);
+void flashconsole_tx_byte(unsigned char c);
+void flashconsole_tx_flush(void);
+
+#define __CONSOLE_FLASH_ENABLE__	IS_ENABLED(CONFIG_CONSOLE_SPI_FLASH)
+
+#if __CONSOLE_FLASH_ENABLE__
+static inline void __flashconsole_init(void)	{ flashconsole_init(); }
+static inline void __flashconsole_tx_byte(u8 data)
+{
+	flashconsole_tx_byte(data);
+}
+static inline void __flashconsole_tx_flush(void)
+{
+	flashconsole_tx_flush();
+}
+#else
+static inline void __flashconsole_init(void)	{}
+static inline void __flashconsole_tx_byte(u8 data)	{}
+static inline void __flashconsole_tx_flush(void)	{}
+#endif /* __CONSOLE_FLASH_ENABLE__ */
+
+
+#endif /* CONSOLE_FLASH_H */