docs: mtd: move it to the driver-api book

[linux-2.6-block.git] / Documentation / mtd / intel-spi.rst

diff --git a/Documentation/mtd/intel-spi.rst b/Documentation/mtd/intel-spi.rst
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-==============================
-Upgrading BIOS using intel-spi
-==============================
-
-Many Intel CPUs like Baytrail and Braswell include SPI serial flash host
-controller which is used to hold BIOS and other platform specific data.
-Since contents of the SPI serial flash is crucial for machine to function,
-it is typically protected by different hardware protection mechanisms to
-avoid accidental (or on purpose) overwrite of the content.
-
-Not all manufacturers protect the SPI serial flash, mainly because it
-allows upgrading the BIOS image directly from an OS.
-
-The intel-spi driver makes it possible to read and write the SPI serial
-flash, if certain protection bits are not set and locked. If it finds
-any of them set, the whole MTD device is made read-only to prevent
-partial overwrites. By default the driver exposes SPI serial flash
-contents as read-only but it can be changed from kernel command line,
-passing "intel-spi.writeable=1".
-
-Please keep in mind that overwriting the BIOS image on SPI serial flash
-might render the machine unbootable and requires special equipment like
-Dediprog to revive. You have been warned!
-
-Below are the steps how to upgrade MinnowBoard MAX BIOS directly from
-Linux.
-
- 1) Download and extract the latest Minnowboard MAX BIOS SPI image
-    [1]. At the time writing this the latest image is v92.
-
- 2) Install mtd-utils package [2]. We need this in order to erase the SPI
-    serial flash. Distros like Debian and Fedora have this prepackaged with
-    name "mtd-utils".
-
- 3) Add "intel-spi.writeable=1" to the kernel command line and reboot
-    the board (you can also reload the driver passing "writeable=1" as
-    module parameter to modprobe).
-
- 4) Once the board is up and running again, find the right MTD partition
-    (it is named as "BIOS")::
-
-       # cat /proc/mtd
-       dev:    size   erasesize  name
-       mtd0: 00800000 00001000 "BIOS"
-
-    So here it will be /dev/mtd0 but it may vary.
-
- 5) Make backup of the existing image first::
-
-       # dd if=/dev/mtd0ro of=bios.bak
-       16384+0 records in
-       16384+0 records out
-       8388608 bytes (8.4 MB) copied, 10.0269 s, 837 kB/s
-
- 6) Verify the backup:
-
-       # sha1sum /dev/mtd0ro bios.bak
-       fdbb011920572ca6c991377c4b418a0502668b73  /dev/mtd0ro
-       fdbb011920572ca6c991377c4b418a0502668b73  bios.bak
-
-    The SHA1 sums must match. Otherwise do not continue any further!
-
- 7) Erase the SPI serial flash. After this step, do not reboot the
-    board! Otherwise it will not start anymore::
-
-       # flash_erase /dev/mtd0 0 0
-       Erasing 4 Kibyte @ 7ff000 -- 100 % complete
-
- 8) Once completed without errors you can write the new BIOS image:
-
-    # dd if=MNW2MAX1.X64.0092.R01.1605221712.bin of=/dev/mtd0
-
- 9) Verify that the new content of the SPI serial flash matches the new
-    BIOS image::
-
-       # sha1sum /dev/mtd0ro MNW2MAX1.X64.0092.R01.1605221712.bin
-       9b4df9e4be2057fceec3a5529ec3d950836c87a2  /dev/mtd0ro
-       9b4df9e4be2057fceec3a5529ec3d950836c87a2 MNW2MAX1.X64.0092.R01.1605221712.bin
-
-    The SHA1 sums should match.
-
- 10) Now you can reboot your board and observe the new BIOS starting up
-     properly.
-
-References
-----------
-
-[1] https://firmware.intel.com/sites/default/files/MinnowBoard%2EMAX_%2EX64%2E92%2ER01%2Ezip
-
-[2] http://www.linux-mtd.infradead.org/