bootcount_ext: Add flag to enable/disable bootcount

After a successful upgrade, multiple problem during boot sequence may
trigger the altbootcmd process.
This patch adds a version and an upgrade_available entries to the
bootcount file to enable/disable the bootcount check.
When failing to read the bootcount file it will consider that bootcount is
enabled, acting as previously, and update the file accordingly.

The bootcount file is only saved when `upgrade_available` is true, this
allows to save writes to the filesystem.

Signed-off-by: Frédéric Danis <frederic.danis@collabora.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

1 files changed, 34 insertions, 12 deletions

diff --git a/drivers/bootcount/bootcount_ext.c b/drivers/bootcount/bootcount_ext.c
index 075e590896..9639e638e9 100644
--- a/drivers/bootcount/bootcount_ext.c
+++ b/drivers/bootcount/bootcount_ext.c
@@ -7,11 +7,21 @@
 #include <fs.h>
 #include <mapmem.h>
 
-#define BC_MAGIC	0xbc
+#define BC_MAGIC	0xbd
+#define BC_VERSION	1
+
+typedef struct {
+	u8 magic;
+	u8 version;
+	u8 bootcount;
+	u8 upgrade_available;
+} bootcount_ext_t;
+
+static u8 upgrade_available = 1;
 
 void bootcount_store(ulong a)
 {
-	u8 *buf;
+	bootcount_ext_t *buf;
 	loff_t len;
 	int ret;
 
@@ -21,20 +31,27 @@ void bootcount_store(ulong a)
 		return;
 	}
 
-	buf = map_sysmem(CONFIG_SYS_BOOTCOUNT_ADDR, 2);
-	buf[0] = BC_MAGIC;
-	buf[1] = (a & 0xff);
+	/* Only update bootcount during upgrade process */
+	if (!upgrade_available)
+		return;
+
+	buf = map_sysmem(CONFIG_SYS_BOOTCOUNT_ADDR, sizeof(bootcount_ext_t));
+	buf->magic = BC_MAGIC;
+	buf->version = BC_VERSION;
+	buf->bootcount = (a & 0xff);
+	buf->upgrade_available = upgrade_available;
 	unmap_sysmem(buf);
 
 	ret = fs_write(CONFIG_SYS_BOOTCOUNT_EXT_NAME,
-		       CONFIG_SYS_BOOTCOUNT_ADDR, 0, 2, &len);
+		       CONFIG_SYS_BOOTCOUNT_ADDR, 0, sizeof(bootcount_ext_t),
+		       &len);
 	if (ret != 0)
 		puts("Error storing bootcount\n");
 }
 
 ulong bootcount_load(void)
 {
-	u8 *buf;
+	bootcount_ext_t *buf;
 	loff_t len_read;
 	int ret;
 
@@ -45,15 +62,20 @@ ulong bootcount_load(void)
 	}
 
 	ret = fs_read(CONFIG_SYS_BOOTCOUNT_EXT_NAME, CONFIG_SYS_BOOTCOUNT_ADDR,
-		      0, 2, &len_read);
-	if (ret != 0 || len_read != 2) {
+		      0, sizeof(bootcount_ext_t), &len_read);
+	if (ret != 0 || len_read != sizeof(bootcount_ext_t)) {
 		puts("Error loading bootcount\n");
 		return 0;
 	}
 
-	buf = map_sysmem(CONFIG_SYS_BOOTCOUNT_ADDR, 2);
-	if (buf[0] == BC_MAGIC)
-		ret = buf[1];
+	buf = map_sysmem(CONFIG_SYS_BOOTCOUNT_ADDR, sizeof(bootcount_ext_t));
+	if (buf->magic == BC_MAGIC && buf->version == BC_VERSION) {
+		upgrade_available = buf->upgrade_available;
+		if (upgrade_available)
+			ret = buf->bootcount;
+	} else {
+		puts("Incorrect bootcount file\n");
+	}
 
 	unmap_sysmem(buf);