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>

8 files changed, 256 insertions, 3 deletions

diff --git a/Makefile.inc b/Makefile.inc
index 1e65228841..99110ed538 100644
--- a/Makefile.inc
+++ b/Makefile.inc
@@ -790,9 +790,19 @@ FMAP_BIOS_SIZE := $(shell echo $(CONFIG_CBFS_SIZE) | tr A-F a-f)
 # position and size of flashmap, relative to BIOS_BASE
 FMAP_FMAP_BASE := 0
 FMAP_FMAP_SIZE := 0x100
+# position, size and entry line of CONSOLE relative to BIOS_BASE, if enabled
+ifeq ($(CONFIG_CONSOLE_SPI_FLASH),y)
+FMAP_CONSOLE_BASE := $(call int-add, $(FMAP_FMAP_BASE) $(FMAP_FMAP_SIZE))
+FMAP_CONSOLE_SIZE := $(CONFIG_CONSOLE_SPI_FLASH_BUFFER_SIZE)
+FMAP_CONSOLE_ENTRY := CONSOLE@$(FMAP_CONSOLE_BASE) $(FMAP_CONSOLE_SIZE)
+else # ifeq ($(CONFIG_CONSOLE_SPI_FLASH),y)
+FMAP_CONSOLE_BASE := 0
+FMAP_CONSOLE_SIZE := 0
+FMAP_CONSOLE_ENTRY :=
+endif # ifeq ($(CONFIG_CONSOLE_SPI_FLASH),y)
 # position and size of CBFS, relative to BIOS_BASE
-FMAP_CBFS_BASE := $(FMAP_FMAP_SIZE)
-FMAP_CBFS_SIZE := $(call int-subtract, $(FMAP_BIOS_SIZE) $(FMAP_FMAP_SIZE))
+FMAP_CBFS_BASE := $(call int-add, $(FMAP_CONSOLE_SIZE) $(FMAP_FMAP_SIZE))
+FMAP_CBFS_SIZE := $(call int-subtract, $(FMAP_BIOS_SIZE) $(FMAP_CBFS_BASE))
 else # ifeq ($(CONFIG_ARCH_X86),y)
 DEFAULT_FLASHMAP:=$(top)/util/cbfstool/default.fmd
 # entire flash
@@ -805,8 +815,18 @@ FMAP_BIOS_SIZE := $(CONFIG_CBFS_SIZE)
 # position and size of flashmap, relative to BIOS_BASE
 FMAP_FMAP_BASE := 0x20000
 FMAP_FMAP_SIZE := 0x100
+# position, size and entry line of CONSOLE relative to BIOS_BASE, if enabled
+ifeq ($(CONFIG_CONSOLE_SPI_FLASH),y)
+FMAP_CONSOLE_BASE := $(call int-add, $(FMAP_FMAP_BASE) $(FMAP_FMAP_SIZE))
+FMAP_CONSOLE_SIZE := $(CONFIG_CONSOLE_SPI_FLASH_BUFFER_SIZE)
+FMAP_CONSOLE_ENTRY := CONSOLE@$(FMAP_CONSOLE_BASE) $(FMAP_CONSOLE_SIZE)
+else # ifeq ($(CONFIG_CONSOLE_SPI_FLASH),y)
+FMAP_CONSOLE_BASE := 0
+FMAP_CONSOLE_SIZE := 0
+FMAP_CONSOLE_ENTRY :=
+endif # ifeq ($(CONFIG_CONSOLE_SPI_FLASH),y)
 # position and size of CBFS, relative to BIOS_BASE
-FMAP_CBFS_BASE := $(call int-add,$(FMAP_FMAP_BASE) $(FMAP_FMAP_SIZE))
+FMAP_CBFS_BASE := $(call int-add,$(FMAP_FMAP_BASE) $(FMAP_FMAP_SIZE) $(FMAP_CONSOLE_SIZE))
 FMAP_CBFS_SIZE := $(call int-subtract,$(FMAP_BIOS_SIZE) $(FMAP_CBFS_BASE))
 endif # ifeq ($(CONFIG_ARCH_X86),y)
 
@@ -817,6 +837,7 @@ $(obj)/fmap.fmd: $(top)/Makefile.inc $(DEFAULT_FLASHMAP) $(obj)/config.h
 	    -e "s,##BIOS_SIZE##,$(FMAP_BIOS_SIZE)," \
 	    -e "s,##FMAP_BASE##,$(FMAP_FMAP_BASE)," \
 	    -e "s,##FMAP_SIZE##,$(FMAP_FMAP_SIZE)," \
+	    -e "s,##CONSOLE_ENTRY##,$(FMAP_CONSOLE_ENTRY)," \
 	    -e "s,##CBFS_BASE##,$(FMAP_CBFS_BASE)," \
 	    -e "s,##CBFS_SIZE##,$(FMAP_CBFS_SIZE)," \
 		$(DEFAULT_FLASHMAP) > $@.tmp
diff --git a/src/console/Kconfig b/src/console/Kconfig
index caf91ab252..c0e4a8c8b0 100644
--- a/src/console/Kconfig
+++ b/src/console/Kconfig
@@ -233,6 +233,37 @@ config CONSOLE_CBMEM_DUMP_TO_UART
 
 endif
 
+config CONSOLE_SPI_FLASH
+	bool "SPI Flash console output"
+	default n
+	select BOOT_DEVICE_SPI_FLASH_RW_NOMMAP_EARLY if !COMMON_CBFS_SPI_WRAPPER
+	help
+	  Send coreboot debug output to the SPI Flash in the FMAP CONSOLE area
+
+	  This option can cause premature wear on the SPI flash and should not
+	  be used as a normal means of debugging. It is only to be enabled and
+	  used when porting a new motherboard which has no other console
+	  available (no UART, no POST, no cbmem access(non bootable)). Since
+	  a non bootable machine will require the use of an external SPI Flash
+	  programmer, the developer can grab the console log at the same time.
+
+	  The flash console will not be erased on reboot, so once it is full,
+	  the flashconsole driver will stop writing to it. This is to avoid
+	  wear on the flash, and to avoid erasing sectors (which may freeze
+	  the SPI controller on skylake).
+
+	  The 'CONSOLE' area can be extracted from the FMAP with :
+	  cbfstool rom.bin read -r CONSOLE -f console.log
+
+config CONSOLE_SPI_FLASH_BUFFER_SIZE
+	hex "Room allocated for console output in FMAP"
+	default 0x20000
+	depends on CONSOLE_SPI_FLASH
+	help
+	  Space allocated for console output storage in FMAP. The default
+	  value (128K or 0x20000 bytes) is large enough to accommodate
+	  even the BIOS_SPEW level.
+
 config CONSOLE_QEMU_DEBUGCON
 	bool "QEMU debug console output"
 	depends on BOARD_EMULATION_QEMU_X86
diff --git a/src/console/console.c b/src/console/console.c
index 7b0dfc2fb1..877c8dc960 100644
--- a/src/console/console.c
+++ b/src/console/console.c
@@ -21,6 +21,7 @@
 #include <console/uart.h>
 #include <console/usb.h>
 #include <console/spi.h>
+#include <console/flash.h>
 #include <rules.h>
 
 void console_hw_init(void)
@@ -33,6 +34,7 @@ void console_hw_init(void)
 	__ne2k_init();
 	__usbdebug_init();
 	__spiconsole_init();
+	__flashconsole_init();
 }
 
 void console_tx_byte(unsigned char byte)
@@ -53,6 +55,7 @@ void console_tx_byte(unsigned char byte)
 	__ne2k_tx_byte(byte);
 	__usb_tx_byte(byte);
 	__spiconsole_tx_byte(byte);
+	__flashconsole_tx_byte(byte);
 }
 
 void console_tx_flush(void)
@@ -60,6 +63,7 @@ void console_tx_flush(void)
 	__uart_tx_flush();
 	__ne2k_tx_flush();
 	__usb_tx_flush();
+	__flashconsole_tx_flush();
 }
 
 void console_write_line(uint8_t *buffer, size_t number_of_bytes)
diff --git a/src/drivers/spi/Makefile.inc b/src/drivers/spi/Makefile.inc
index c1bf307cc5..c594d4e74c 100644
--- a/src/drivers/spi/Makefile.inc
+++ b/src/drivers/spi/Makefile.inc
@@ -7,6 +7,14 @@ ramstage-y += spiconsole.c
 smm-$(CONFIG_DEBUG_SMI) += spiconsole.c
 endif
 
+ifeq ($(CONFIG_CONSOLE_SPI_FLASH),y)
+bootblock-y += flashconsole.c
+romstage-y += flashconsole.c
+ramstage-y += flashconsole.c
+smm-$(CONFIG_DEBUG_SMI) += flashconsole.c
+
+endif
+
 bootblock-y += spi-generic.c
 bootblock-$(CONFIG_COMMON_CBFS_SPI_WRAPPER) += cbfs_spi.c
 bootblock-$(CONFIG_SPI_FLASH) += spi_flash.c
diff --git a/src/drivers/spi/flashconsole.c b/src/drivers/spi/flashconsole.c
new file mode 100644
index 0000000000..e73af22951
--- /dev/null
+++ b/src/drivers/spi/flashconsole.c
@@ -0,0 +1,142 @@
+/*
+ * 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.
+ */
+
+#include <arch/early_variables.h>
+#include <region.h>
+#include <boot_device.h>
+#include <fmap.h>
+#include <console/console.h>
+#include <console/flash.h>
+#include <string.h>
+
+#define LINE_BUFFER_SIZE 128
+#define READ_BUFFER_SIZE 0x100
+
+static const struct region_device *g_rdev_ptr CAR_GLOBAL;
+static struct region_device g_rdev CAR_GLOBAL;
+static uint8_t g_line_buffer[LINE_BUFFER_SIZE] CAR_GLOBAL;
+static size_t g_offset CAR_GLOBAL;
+static size_t g_line_offset CAR_GLOBAL;
+
+void flashconsole_init(void)
+{
+	struct region_device *rdev = car_get_var_ptr(&g_rdev);
+	uint8_t buffer[READ_BUFFER_SIZE];
+	size_t size;
+	size_t offset = 0;
+	size_t len = READ_BUFFER_SIZE;
+	size_t i;
+
+	if (fmap_locate_area_as_rdev_rw("CONSOLE", rdev)) {
+		printk(BIOS_INFO, "Can't find 'CONSOLE' area in FMAP\n");
+		return;
+	}
+	size = region_device_sz(rdev);
+
+	/*
+	 * We need to check the region until we find a 0xff indicating
+	 * the end of a previous log write.
+	 * We can't erase the region because one stage would erase the
+	 * data from the previous stage. Also, it looks like doing an
+	 * erase could completely freeze the SPI controller and then
+	 * we can't write anything anymore (apparently might happen if
+	 * the sector is already erased, so we would need to read
+	 * anyways to check if it's all 0xff).
+	 */
+	for (i = 0; i < len && offset < size; ) {
+		// Fill the buffer on first iteration
+		if (i == 0) {
+			len = min(READ_BUFFER_SIZE, size - offset);
+			if (rdev_readat(rdev, buffer, offset, len) != len)
+				return;
+		}
+		if (buffer[i] == 0xff) {
+			offset += i;
+			break;
+		}
+		// If we're done, repeat the process for the next sector
+		if (++i == READ_BUFFER_SIZE) {
+			offset += len;
+			i = 0;
+		}
+	}
+	// Make sure there is still space left on the console
+	if (offset >= size) {
+		printk(BIOS_INFO, "No space left on 'console' region in SPI flash\n");
+		return;
+	}
+
+	car_set_var(g_offset, offset);
+	/* Set g_rdev_ptr last so tx_byte doesn't get executed early */
+	car_set_var(g_rdev_ptr, rdev);
+}
+
+void flashconsole_tx_byte(unsigned char c)
+{
+	const struct region_device *rdev = car_get_var(g_rdev_ptr);
+	uint8_t *line_buffer;
+	size_t offset;
+	size_t len;
+	size_t region_size;
+
+	if (!rdev)
+		return;
+
+	line_buffer = car_get_var_ptr(g_line_buffer);
+	offset = car_get_var(g_offset);
+	len = car_get_var(g_line_offset);
+	region_size = region_device_sz(rdev);
+
+	line_buffer[len++] = c;
+	car_set_var(g_line_offset, len);
+
+	if (len >= LINE_BUFFER_SIZE ||
+		offset + len >= region_size || c == '\n') {
+		flashconsole_tx_flush();
+	}
+}
+
+void flashconsole_tx_flush(void)
+{
+	const struct region_device *rdev = car_get_var(g_rdev_ptr);
+	uint8_t *line_buffer = car_get_var_ptr(g_line_buffer);
+	size_t offset = car_get_var(g_offset);
+	size_t len = car_get_var(g_line_offset);
+	size_t region_size;
+
+	if (!rdev)
+		return;
+
+	/* Prevent any recursive loops in case the spi flash driver
+	 * calls printk (in case of transaction timeout or
+	 * any other error while writing) */
+	car_set_var(g_rdev_ptr, NULL);
+
+	region_size = region_device_sz(rdev);
+	if (offset + len >= region_size)
+		len = region_size - offset;
+
+	if (rdev_writeat(rdev, line_buffer, offset, len) != len)
+		rdev = NULL;
+
+	// If the region is full, stop future write attempts
+	if (offset + len >= region_size)
+		rdev = NULL;
+
+	car_set_var(g_offset, offset + len);
+	car_set_var(g_line_offset, 0);
+
+	car_set_var(g_rdev_ptr, rdev);
+}
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 */
diff --git a/util/cbfstool/default-x86.fmd b/util/cbfstool/default-x86.fmd
index f344ab2086..1b6cfc8ba6 100644
--- a/util/cbfstool/default-x86.fmd
+++ b/util/cbfstool/default-x86.fmd
@@ -10,6 +10,7 @@
 FLASH@##ROM_BASE## ##ROM_SIZE## {
 	BIOS@##BIOS_BASE## ##BIOS_SIZE## {
 		FMAP@##FMAP_BASE## ##FMAP_SIZE##
+		##CONSOLE_ENTRY##
 		COREBOOT(CBFS)@##CBFS_BASE## ##CBFS_SIZE##
 	}
 }
diff --git a/util/cbfstool/default.fmd b/util/cbfstool/default.fmd
index 32ddfa4074..50b9bf0bd1 100644
--- a/util/cbfstool/default.fmd
+++ b/util/cbfstool/default.fmd
@@ -13,6 +13,7 @@ FLASH@##ROM_BASE## ##ROM_SIZE## {
 	BIOS@##BIOS_BASE## ##BIOS_SIZE## {
 		BOOTBLOCK 128K
 		FMAP@##FMAP_BASE## ##FMAP_SIZE##
+		##CONSOLE_ENTRY##
 		COREBOOT(CBFS)@##CBFS_BASE## ##CBFS_SIZE##
 	}
 }