ELOG: Add support for a monotonic boot counter in CMOS

This maintains a 32bit monotonically increasing boot counter
that is stored in CMOS and logged on every non-S3 boot when
the event log is initialized.

In CMOS the count is prefixed with a 16bit signature and
appended with a 16bit checksum.

This counter is incremented in sandybridge early_init which is
called by romstage.  It is incremented early in order notice
when reboots happen after memory init.

The counter is then logged when ELOG is initialized and will
store the boot count as part of a 'System boot; event.

Reboot a few times and look for 'System boot' events in the
event log and check that they are increasing.  Also verify
that the counter does NOT increase when resuming from S3.

171 | 2012-06-23 16:02:55 | System boot | 285
176 | 2012-06-23 16:26:00 | System boot | 286
182 | 2012-06-23 16:27:04 | System boot | 287
189 | 2012-06-23 16:31:10 | System boot | 288

Change-Id: I23faeafcf155edfd10aa6882598b3883575f8a33
Signed-off-by: Duncan Laurie <dlaurie@chromium.org>
Reviewed-on: http://review.coreboot.org/1315
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>

4 files changed, 148 insertions, 0 deletions

diff --git a/src/drivers/elog/Kconfig b/src/drivers/elog/Kconfig
index d61dd10857..867416cc77 100644
--- a/src/drivers/elog/Kconfig
+++ b/src/drivers/elog/Kconfig
@@ -67,3 +67,20 @@ config ELOG_SHRINK_SIZE
 	  Default is 1K.
 
 endif
+
+config ELOG_BOOT_COUNT
+	depends on ELOG
+	bool "Maintain a monotonic boot number in CMOS"
+	default n
+	help
+	  Store a monotonic boot number in CMOS and provide an interface
+	  to read the current value and increment the counter.  This boot
+	  counter will be logged as part of the System Boot event.
+
+config ELOG_BOOT_COUNT_CMOS_OFFSET
+	depends on ELOG && ELOG_BOOT_COUNT && !USE_OPTION_TABLE
+	int "Offset in CMOS to store the boot count"
+	default 0
+	help
+	  This value must be greater than 16 bytes so as not to interfere
+	  with the standard RTC region.  Requires 8 bytes.
diff --git a/src/drivers/elog/Makefile.inc b/src/drivers/elog/Makefile.inc
index a01841db96..32509c8ce0 100644
--- a/src/drivers/elog/Makefile.inc
+++ b/src/drivers/elog/Makefile.inc
@@ -1 +1,4 @@
 ramstage-$(CONFIG_ELOG) += elog.c
+
+romstage-$(CONFIG_ELOG_BOOT_COUNT) += boot_count.c
+ramstage-$(CONFIG_ELOG_BOOT_COUNT) += boot_count.c
diff --git a/src/drivers/elog/boot_count.c b/src/drivers/elog/boot_count.c
new file mode 100644
index 0000000000..9ea828d04d
--- /dev/null
+++ b/src/drivers/elog/boot_count.c
@@ -0,0 +1,122 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright (C) 2012 The ChromiumOS Authors.  All rights reserved.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA, 02110-1301 USA
+ */
+
+#include <console/console.h>
+#include <ip_checksum.h>
+#include <pc80/mc146818rtc.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <elog.h>
+
+/*
+ * We need a region in CMOS to store the boot counter.
+ *
+ * This can either be declared as part of the option
+ * table or statically defined in the board config.
+ */
+#if CONFIG_USE_OPTION_TABLE
+# include "option_table.h"
+# define BOOT_COUNT_CMOS_OFFSET (CMOS_VSTART_boot_count_offset >> 3)
+#else
+# if defined(CONFIG_ELOG_BOOT_COUNT_CMOS_OFFSET)
+#  define BOOT_COUNT_CMOS_OFFSET CONFIG_ELOG_BOOT_COUNT_CMOS_OFFSET
+# else
+#  error "Must define CONFIG_ELOG_BOOT_COUNT_CMOS_OFFSET"
+# endif
+#endif
+
+#define BOOT_COUNT_SIGNATURE 0x4342 /* 'BC' */
+
+struct boot_count {
+	u16 signature;
+	u32 count;
+	u16 checksum;
+} __attribute__ ((packed));
+
+/* Read and validate boot count structure from CMOS */
+static int boot_count_cmos_read(struct boot_count *bc)
+{
+	u8 i, *p;
+	u16 csum;
+
+	for (p = (u8*)bc, i = 0; i < sizeof(*bc); i++, p++)
+		*p = cmos_read(BOOT_COUNT_CMOS_OFFSET + i);
+
+	/* Verify signature */
+	if (bc->signature != BOOT_COUNT_SIGNATURE) {
+		printk(BIOS_DEBUG, "Boot Count invalid signature\n");
+		return -1;
+	}
+
+	/* Verify checksum over signature and counter only */
+	csum = compute_ip_checksum(bc, offsetof(struct boot_count, checksum));
+
+	if (csum != bc->checksum) {
+		printk(BIOS_DEBUG, "Boot Count checksum mismatch\n");
+		return -1;
+	}
+
+	return 0;
+}
+
+/* Write boot count structure to CMOS */
+static void boot_count_cmos_write(struct boot_count *bc)
+{
+	u8 i, *p;
+
+	/* Checksum over signature and counter only */
+	bc->checksum = compute_ip_checksum(
+		bc, offsetof(struct boot_count, checksum));
+
+	for (p = (u8*)bc, i = 0; i < sizeof(*bc); i++, p++)
+		cmos_write(*p, BOOT_COUNT_CMOS_OFFSET + i);
+}
+
+/* Increment boot count and return the new value */
+u32 boot_count_increment(void)
+{
+	struct boot_count bc;
+
+	/* Read and increment boot count */
+	if (boot_count_cmos_read(&bc) < 0) {
+		/* Structure invalid, re-initialize */
+		bc.signature = BOOT_COUNT_SIGNATURE;
+		bc.count = 0;
+	}
+
+	/* Increment boot counter */
+	bc.count++;
+
+	/* Write the new count to CMOS */
+	boot_count_cmos_write(&bc);
+
+	printk(BIOS_DEBUG, "Boot Count incremented to %u\n", bc.count);
+	return bc.count;
+}
+
+/* Return the current boot count */
+u32 boot_count_read(void)
+{
+	struct boot_count bc;
+
+	if (boot_count_cmos_read(&bc) < 0)
+		return 0;
+
+	return bc.count;
+}
diff --git a/src/drivers/elog/elog.c b/src/drivers/elog/elog.c
index 9c0fa930ad..1219883907 100644
--- a/src/drivers/elog/elog.c
+++ b/src/drivers/elog/elog.c
@@ -780,6 +780,12 @@ int elog_init(void)
 		elog_add_event_word(ELOG_TYPE_LOG_CLEAR,
 				    elog_get_flash()->total_size);
 
+#if CONFIG_ELOG_BOOT_COUNT && !defined(__SMM__)
+	/* Log boot count event except in S3 resume */
+	if (acpi_slp_type != 3)
+		elog_add_event_dword(ELOG_TYPE_BOOT, boot_count_read());
+#endif
+
 	return 0;
 }