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Message-ID: <CAD6G_RQEBy_-eY_ZnF44J3iemq+ZVazziiPmdRHqqxaieEyAKA@mail.gmail.com> Date: Wed, 10 Aug 2016 01:02:09 +0530 From: Jagan Teki <jagannadh.teki@...il.com> To: Mika Westerberg <mika.westerberg@...ux.intel.com> Cc: "linux-mtd@...ts.infradead.org" <linux-mtd@...ts.infradead.org>, Brian Norris <computersforpeace@...il.com>, David Woodhouse <dwmw2@...radead.org>, Lee Jones <lee.jones@...aro.org>, Peter Tyser <ptyser@...-inc.com>, key.seong.lim@...el.com, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org> Subject: Re: [PATCH v2 1/3] spi-nor: Add support for Intel SPI serial flash controller On 22 June 2016 at 21:02, Mika Westerberg <mika.westerberg@...ux.intel.com> wrote: > Add support for the SPI serial flash host controller found on many Intel > CPUs including Baytrail and Braswell. The SPI serial flash controller is > used to access BIOS and other platform specific information. By default the > driver exposes a single read-only MTD device but with a module parameter > "writeable=1" the MTD device can be made read-write which makes it possible > to upgrade BIOS directly from Linux. > > Signed-off-by: Mika Westerberg <mika.westerberg@...ux.intel.com> > --- > Documentation/mtd/intel-spi.txt | 88 ++++ > drivers/mtd/spi-nor/Kconfig | 20 + > drivers/mtd/spi-nor/Makefile | 2 + > drivers/mtd/spi-nor/intel-spi-platform.c | 57 +++ > drivers/mtd/spi-nor/intel-spi.c | 773 +++++++++++++++++++++++++++++++ > drivers/mtd/spi-nor/intel-spi.h | 24 + > include/linux/platform_data/intel-spi.h | 31 ++ > 7 files changed, 995 insertions(+) > create mode 100644 Documentation/mtd/intel-spi.txt > create mode 100644 drivers/mtd/spi-nor/intel-spi-platform.c > create mode 100644 drivers/mtd/spi-nor/intel-spi.c > create mode 100644 drivers/mtd/spi-nor/intel-spi.h > create mode 100644 include/linux/platform_data/intel-spi.h > > diff --git a/Documentation/mtd/intel-spi.txt b/Documentation/mtd/intel-spi.txt > new file mode 100644 > index 000000000000..bc357729c2cb > --- /dev/null > +++ b/Documentation/mtd/intel-spi.txt > @@ -0,0 +1,88 @@ > +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.MAX_.X64.92.R01.zip > +[2] http://www.linux-mtd.infradead.org/ > diff --git a/drivers/mtd/spi-nor/Kconfig b/drivers/mtd/spi-nor/Kconfig > index d42c98e1f581..119712b6ae3b 100644 > --- a/drivers/mtd/spi-nor/Kconfig > +++ b/drivers/mtd/spi-nor/Kconfig > @@ -49,4 +49,24 @@ config SPI_NXP_SPIFI > Flash. Enable this option if you have a device with a SPIFI > controller and want to access the Flash as a mtd device. > > +config SPI_INTEL_SPI > + tristate > + > +config SPI_INTEL_SPI_PLATFORM > + tristate "Intel PCH/PCU SPI flash platform driver" if EXPERT > + depends on X86 > + select SPI_INTEL_SPI > + help > + This enables platform support for the Intel PCH/PCU SPI > + controller in master mode. This controller is present in modern > + Intel hardware and is used to hold BIOS and other persistent > + settings. Using this driver it is possible to upgrade BIOS > + directly from Linux. > + > + Say N here unless you know what you are doing. Overwriting the > + SPI flash may render the system unbootable. > + > + To compile this driver as a module, choose M here: the module > + will be called intel-spi-platform. > + > endif # MTD_SPI_NOR > diff --git a/drivers/mtd/spi-nor/Makefile b/drivers/mtd/spi-nor/Makefile > index 0bf3a7f81675..60c0b1bb8264 100644 > --- a/drivers/mtd/spi-nor/Makefile > +++ b/drivers/mtd/spi-nor/Makefile > @@ -2,3 +2,5 @@ obj-$(CONFIG_MTD_SPI_NOR) += spi-nor.o > obj-$(CONFIG_SPI_FSL_QUADSPI) += fsl-quadspi.o > obj-$(CONFIG_MTD_MT81xx_NOR) += mtk-quadspi.o > obj-$(CONFIG_SPI_NXP_SPIFI) += nxp-spifi.o > +obj-$(CONFIG_SPI_INTEL_SPI) += intel-spi.o > +obj-$(CONFIG_SPI_INTEL_SPI_PLATFORM) += intel-spi-platform.o Why is this separate platform driver, can't we combine with single spi-nor controller driver, any specific reason? -- Jagan Teki Free Software Engineer | www.openedev.com U-Boot, Linux | Upstream contributor/maintainer Hyderabad, India.
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