Hi John:

On 2016?01?16? 04:27, John Stultz wrote:

On Tue, Jan 12, 2016 at 3:31 AM, Andy Yan [off-list ref] wrote:

quoted

This driver parse the reboot commands like "reboot loader"
and "reboot recovery" to get a boot mode described in the
device tree , then call the write interfae to store the boot
mode in some persistent storage  like special register or ram,
which can be read by the bootloader after system reboot, then
the bootloader can take different action according to the mode
stored.

This is commonly used on Android based devices, which in order
to reboot the device into fastboot or recovery mode.

Signed-off-by: Andy Yan <andy.yan@rock-chips.com>

Hey Andy!
   Thanks for keeping this work going! I've just successfully reworked
my Nexus7 tree to use your implementation (using the syscon version,
setting up a syscon for IMEM as Bjorn had requested earlier).

All is working well so far!

The one thing I was working on supporting with my own version that
seems to be missing here are for devices that use string based codes,
rather then magic numbers.

This was mostly a theoretical issue. I think the Galaxy Nexus used it,
and when I was looking at some of the HTC devices, they support a text
based reason along with the magic code, but at least in some
implementations the text mode isn't used, so I suspect there its just
for extra debugging.  So this may not be critical to solve until
someone tries to add support for such a device.

Anyway, I'm going to look at porting this to the HiKey board next
(which just uses reserved ram, not syscon), so I'll try to do a an
SRAM driver implementaiton to see how that goes.

thanks!
-john

  Very glad to hear news from you. And welcome your SRAM based driver 
implementation.