[U-Boot] [PATCH v2 1/5] bootcount: store bootcount var in environment

[Heiko Schocher <hs@denx.de>]

If no softreset save registers are found on the hardware
"bootcount" is stored in the environment. To prevent a
saveenv on all reboots, the environment variable
"upgrade_available" is introduced. If "upgrade_available" is
0, "bootcount" is always 0 therefore no need to save the
environment on u-boot boot, if "upgrade_available" is 1 "bootcount"
is incremented in the environment and environment gets written
on u-boot start.
So the Userspace Applikation must set the "upgrade_available"
and "bootcount" variable to 0 (for example with fw_setenv),
if a boot was successfully.

Signed-off-by: Heiko Schocher <hs@denx.de>
---
- no changes for v2

 README                            | 16 ++++++++++++++++
 drivers/bootcount/Makefile        |  1 +
 drivers/bootcount/bootcount_env.c | 29 +++++++++++++++++++++++++++++
 3 files changed, 46 insertions(+)
 create mode 100644 drivers/bootcount/bootcount_env.c

diff --git a/README b/README
index 232c96a..2558e42 100644
--- a/README
+++ b/README
@@ -784,6 +784,22 @@ The following options need to be configured:
 		as a convenience, when switching between booting from
 		RAM and NFS.
 
+- Bootcount:
+		CONFIG_BOOTCOUNT_LIMIT
+		Implements a mechanism for detecting a repeating reboot
+		cycle, see:
+		http://www.denx.de/wiki/view/DULG/UBootBootCountLimit
+
+		CONFIG_BOOTCOUNT_ENV
+		If no softreset save registers are found on the hardware
+		"bootcount" is stored in the environment. To prevent a
+		saveenv on all reboots, the environment variable
+		"upgrade_available" is used. If "upgrade_available" is
+		0, "bootcount" is always 0, if "upgrade_available" is
+		1 "bootcount" is incremented in the environment.
+		So the Userspace Applikation must set the "upgrade_available"
+		and "bootcount" variable to 0, if a boot was successfully.
+
 - Pre-Boot Commands:
 		CONFIG_PREBOOT
 
diff --git a/drivers/bootcount/Makefile b/drivers/bootcount/Makefile
index 2b517b6..8ec0423 100644
--- a/drivers/bootcount/Makefile
+++ b/drivers/bootcount/Makefile
@@ -11,6 +11,7 @@ COBJS-$(CONFIG_AT91SAM9XE)	+= bootcount_at91.o
 COBJS-$(CONFIG_BLACKFIN)	+= bootcount_blackfin.o
 COBJS-$(CONFIG_SOC_DA8XX)	+= bootcount_davinci.o
 COBJS-$(CONFIG_BOOTCOUNT_RAM)	+= bootcount_ram.o
+COBJS-$(CONFIG_BOOTCOUNT_ENV)	+= bootcount_env.o
 
 COBJS	:= $(COBJS-y)
 SRCS 	:= $(COBJS:.o=.c)
diff --git a/drivers/bootcount/bootcount_env.c b/drivers/bootcount/bootcount_env.c
new file mode 100644
index 0000000..2d6e8db
--- /dev/null
+++ b/drivers/bootcount/bootcount_env.c
@@ -0,0 +1,29 @@
+/*
+ * (C) Copyright 2013
+ * Heiko Schocher, DENX Software Engineering, hs at denx.de.
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+
+void bootcount_store(ulong a)
+{
+	int upgrade_available = getenv_ulong("upgrade_available", 10, 0);
+
+	if (upgrade_available) {
+		setenv_ulong("bootcount", a);
+		saveenv();
+	}
+}
+
+ulong bootcount_load(void)
+{
+	int upgrade_available = getenv_ulong("upgrade_available", 10, 0);
+	ulong val = 0;
+
+	if (upgrade_available)
+		val = getenv_ulong("bootcount", 10, 0);
+
+	return val;
+}
-- 
1.8.3.1