(+Mark, Grant) On 09/10/17 18:16, Chris Metcalf wrote: > The Mellanox BlueField SoC firmware supports a safe upgrade mode as > part of the flow where users put new firmware on the secondary eMMC > boot partition (the one not currently in use), tell the eMMC to make > the secondary boot partition primary, and reset. This driver is > used to request that the firmware start the ARM watchdog after the > next reset, and also request that the firmware swap the eMMC boot > partition back again on the reset after that (the second reset). > This means that if anything goes wrong, the watchdog will fire, the > system will reset, and the firmware will switch back to the original > boot partition. If the boot is successful, the user will use this > driver to put the firmware back into the state where it doesn't touch > the eMMC boot partition at reset, and turn off the ARM watchdog. > > The firmware allows for more configurability than that, as can > be seen in the code, but the use case above is what the driver > primarily supports. > > It is structured as a simple sysfs driver that is loaded based on > an ACPI table entry, and allows reading/writing text strings to > various /sys/bus/platform/drivers/mlx-bootctl/* files. > > Signed-off-by: Chris Metcalf <cmetc...@mellanox.com> > --- > Ingo, since there isn't an overall maintainer for drivers/firmware, > does it make sense for this to go through your tree? Thanks! > > drivers/firmware/Kconfig | 12 +++ > drivers/firmware/Makefile | 1 + > drivers/firmware/mlx-bootctl.c | 222 > +++++++++++++++++++++++++++++++++++++++++ > drivers/firmware/mlx-bootctl.h | 103 +++++++++++++++++++ > 4 files changed, 338 insertions(+) > create mode 100644 drivers/firmware/mlx-bootctl.c > create mode 100644 drivers/firmware/mlx-bootctl.h > > diff --git a/drivers/firmware/Kconfig b/drivers/firmware/Kconfig > index 6e4ed5a9c6fd..1f2adbcc5acc 100644 > --- a/drivers/firmware/Kconfig > +++ b/drivers/firmware/Kconfig > @@ -230,6 +230,18 @@ config TI_SCI_PROTOCOL > This protocol library is used by client drivers to use the features > provided by the system controller. > > +config MLX_BOOTCTL > + tristate "Mellanox BlueField Firmware Boot Control" > + depends on ARM64 > + help > + The Mellanox BlueField firmware implements functionality to > + request swapping the primary and alternate eMMC boot > + partition, and to set up a watchdog that can undo that swap > + if the system does not boot up correctly. This driver > + provides sysfs access to the firmware, to be used in > + conjunction with the eMMC device driver to do any necessary > + initial swap of the boot partition. > + For me, this looks like any other distro upgrade use-case which requires to set some variable that must persist across reset (i.e. in non volatile memory)
ARM is proposing Embedded Base Boot Requirements (EBBR)[1] and it covers this IIUC. I am not sure if we need to achieve that using SMCCC as proposed in the patch. I may be wrong, but just wanted to check. -- [1] https://developer.arm.com/products/architecture/system-architecture/embedded-system-architecture -- Regards, Sudeep
