path: root/Documentation/mmc
diff options
authorAndrei Warkentin <andreiw@motorola.com>2011-04-11 18:10:25 -0500
committerChris Ball <cjb@laptop.org>2011-05-24 21:01:21 -0400
commit371a689f64b0da140c3bcd3f55305ffa1c3a58ef (patch)
treec0dff82d668378d395cb22ce33cd93e6dafef9eb /Documentation/mmc
parent1a258db6f396e26c2c00b19c0107a891895d4584 (diff)
mmc: MMC boot partitions support.
Allows device MMC boot partitions to be accessed. MMC partitions are treated effectively as separate block devices on the same MMC card. Signed-off-by: Andrei Warkentin <andreiw@motorola.com> Acked-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Chris Ball <cjb@laptop.org>
Diffstat (limited to 'Documentation/mmc')
3 files changed, 39 insertions, 0 deletions
diff --git a/Documentation/mmc/00-INDEX b/Documentation/mmc/00-INDEX
index fca586f5b853..93dd7a714075 100644
--- a/Documentation/mmc/00-INDEX
+++ b/Documentation/mmc/00-INDEX
@@ -2,3 +2,5 @@
- this file
- info on SD and MMC device attributes
+ - info on SD and MMC device partitions
diff --git a/Documentation/mmc/mmc-dev-attrs.txt b/Documentation/mmc/mmc-dev-attrs.txt
index ff2bd685bced..8898a95b41e5 100644
--- a/Documentation/mmc/mmc-dev-attrs.txt
+++ b/Documentation/mmc/mmc-dev-attrs.txt
@@ -1,3 +1,13 @@
+SD and MMC Block Device Attributes
+These attributes are defined for the block devices associated with the
+SD or MMC device.
+The following attributes are read/write.
+ force_ro Enforce read-only access even if write protect switch is off.
SD and MMC Device Attributes
diff --git a/Documentation/mmc/mmc-dev-parts.txt b/Documentation/mmc/mmc-dev-parts.txt
new file mode 100644
index 000000000000..2db28b8e662f
--- /dev/null
+++ b/Documentation/mmc/mmc-dev-parts.txt
@@ -0,0 +1,27 @@
+SD and MMC Device Partitions
+Device partitions are additional logical block devices present on the
+SD/MMC device.
+As of this writing, MMC boot partitions as supported and exposed as
+/dev/mmcblkXboot0 and /dev/mmcblkXboot1, where X is the index of the
+parent /dev/mmcblkX.
+MMC Boot Partitions
+Read and write access is provided to the two MMC boot partitions. Due to
+the sensitive nature of the boot partition contents, which often store
+a bootloader or bootloader configuration tables crucial to booting the
+platform, write access is disabled by default to reduce the chance of
+accidental bricking.
+To enable write access to /dev/mmcblkXbootY, disable the forced read-only
+access with:
+echo 0 > /sys/block/mmcblkXbootY/force_ro
+To re-enable read-only access:
+echo 1 > /sys/block/mmcblkXbootY/force_ro

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