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Add support for the MSTAR I2C ISP protocol

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Basically, among other chips, MSTAR manufactures SoCs that equip TV sets
and computer screens, and it seems that all of their products use the
same in-system programming protocol. Basically, they use the DDC channel
of VGA or DVI connectors, which is actually an I2C bus, to encapsulate
SPI frames (the flash chip is connected to the SoC through an SPI bus).

I wrote this patch since the screen I bought had a software bug, and the
manufacturer only released a new firmware binary, but no tool or
instructions on flashing it.

More details can be found here:
http://boeglin.org/blog/index.php?entry=Flashing-a-BenQ-Z-series-for-free(dom)

I only read code from Linux kernel archives published by Acer to figure
out the protocol (for a touchscreen controller and an NFC chip, both by
MSTAR, that share the same ISP protocol), so I don't think there are
any legal problems with it.

Compilation is currently disabled by default in the Makefile.
If in doubt, additional Makefile bugs were added by Stefan.

Corresponding to flashrom svn r1860.

Signed-off-by: Alexandre Boeglin <alex@boeglin.org>
Signed-off-by: Stefan Tauner <stefan.tauner@alumni.tuwien.ac.at>
Acked-by: Stefan Tauner <stefan.tauner@alumni.tuwien.ac.at>
This commit is contained in:
Alexandre Boeglin
2014-12-20 20:25:19 +00:00
committed by Stefan Tauner
parent 5859ced80f
commit 80e6471588
5 changed files with 339 additions and 0 deletions
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47
flashrom.8.tmpl
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@ -227,6 +227,8 @@ bitbanging adapter)
.sp
.BR "* nicintel_eeprom" " (for SPI EEPROMs on Intel Gigabit network cards)"
.sp
.BR "* mstarddc_spi" " (for SPI flash ROMs accessible through DDC in MSTAR-equipped displays)"
.sp
Some programmers have optional or mandatory parameters which are described
in detail in the
.B PROGRAMMER-SPECIFIC INFORMATION
@ -889,6 +891,51 @@ Example that sets the frequency to 8 MHz:
.B " flashrom \-p linux_spi:dev=/dev/spidevX.Y,spispeed=8000"
.sp
Please note that the linux_spi driver only works on Linux.
.SS
.BR "mstarddc_spi " programmer
The Display Data Channel (DDC) is an I2C bus present on VGA and DVI connectors, that allows exchanging
informations between a computer and attached displays. Its most common uses are getting display capabilities
through EDID (at I2C address 0x50) and sending commands to the display using the DDC/CI protocol (at address
0x37). On displays driven by MSTAR SoCs, it is also possible to access the SoC firmware flash (connected to
the Soc through another SPI bus) using an In-System Programming (ISP) port, usually at address 0x49.
This flashrom module allows the latter via Linux's I2C driver.
.sp
.B IMPORTANT:
Before using this programmer, the display
.B MUST
be in standby mode, and only connected to the computer that will run flashrom using a VGA cable, to an
inactive VGA output. It absolutely
.B MUST NOT
be used as a display during the procedure!
.sp
You have to specify the DDC/I2C controller and I2C address to use with the
.sp
.B " flashrom \-p mstarddc_spi:dev=/dev/i2c-X:YY"
.sp
syntax where
.B /dev/i2c-X
is the Linux device node for your I2C controller connected to the display's DDC channel, and
.B YY
is the (hexadecimal) address of the MSTAR ISP port (address 0x49 is usually used).
Example that uses I2C controller /dev/i2c-1 and address 0x49:
.sp
.B " flashrom \-p mstarddc_spi:dev=/dev/i2c-1:49
.sp
It is also possible to inhibit the reset command that is normally sent to the display once the flashrom
operation is completed using the optional
.B noreset
parameter. A value of 1 prevents flashrom from sending the reset command.
Example that does not reset the display at the end of the operation:
.sp
.B " flashrom \-p mstarddc_spi:dev=/dev/i2c-1:49,noreset=1
.sp
Please note that sending the reset command is also inhibited in the event an error occured during the operation.
To send the reset command afterwards, you can simply run flashrom once more, in chip probe mode (not specifying
an operation), without the
.B noreset
parameter, once the flash read/write operation you intended to perform has completed successfully.
.sp
Please also note that the mstarddc_spi driver only works on Linux.
.SH EXAMPLES
To back up and update your BIOS, run
.sp