AST2600: Linux driver support for SPI controller
Milton Miller II
miltonm at us.ibm.com
Tue Jul 20 02:32:10 AEST 2021
On July 19, 2021, VINOTHKUMAR RK wrote:
>This is regarding SPI controller driver support in OpenBMC.
>Here is the scenario: Three devices connected over same SPI
>controller as mentioned below:
>Firmware SPI Memory Controller (BSPI): (0x1E620000):
> - Flash 0 (CS0)
> - Flash 1 (CS1)
> - MCU/CPLD (CS2)
>When I look at the OpenBMC Linux repository, I could find
>'aspeed-smc.c' driver under the MTD subsystem, so this seems to work
>only for flash devices.
>Do we've any other driver support or a solution to handle all the
>three devices? Any help/suggestions would be appreciated.
I was involved with the driver you found before Cedric took it
I am not aware of anyone writing a generic SPI acccess driver.
The hardwaredoes have a user mode that does not auto-sequence, but
as I remember its limited in that it can not read and write data
at the same time and is limited to transfers that are multiples of
If your MCU/CPLD can live with these limitations then you or
someone can integrate a spi layer driver into the current
Note on the 2600 the hardware for the host is the same as the
hardware for the BMC. It may be easier to develop spi mode on
that port because it could be developed while running with the
BMC from existing driver. Alternatively it could be developed
on a system that runs on eMMC.
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