[PATCH linux dev-4.7 v2 0/1] Enable pinctrl to modify SPI1 strap bits

[Joel Stanley]

On Fri, Nov 4, 2016 at 4:13 AM, Kun Yi <kunyi at google.com> wrote:
> Hi,
>
> Context: re. Andrew's suggestion to a previous RFC proposal[1].
>
> To modify SPI1 mode at runtime, pinctrl subsystem will need to add exception to
> the read-only HWSTRAP rule. This patch does precisely that.
>
> Sending this out as a standalone patch since it seems to me this change could
> also make boot time SPI1 mode configuration easier. Instead of configuring
> the strap bits in mach-aspeed/aspeed.c AND make sure device tree pinctrl
> settings match what was configured, with this change device tree entry
> should dictate default SPI1 mode regardless of what's set previously. E.g.
> following node will be able to configure spi1 in master mode.
>
> &spi1 {
>         status = "okay";
>
>         pinctrl-names = "default";
>         pinctrl-0 = <&pinctrl_spi1_default>;
> };
>
> I saw Joel sent out a patch that configures SPI1 to master for every AST2500
> machine, do we not have any uses currently for other modes?
>
> [1] https://lists.ozlabs.org/pipermail/openbmc/2016-October/005194.html

Not presently. All of the other systems have the BMC as the owner of
the flash, and any operations go through the software on the BMC.

For instance, booting will be done by copying the relevant parts of
flash into SDRAM and pointing the LPC mapping at this location. We
call that 'memboot'.

I like your patches; it's much cleaner to put the desired
configuration in the device tree and have the software do the right
thing than to have hacks in the board file. If Andrew and yourself can
agree on an implmeentaiton, I will remove the setting of the mux from
the board file and go with your patch instead.

Cheers,

Joel
>
> Thanks,
> Kun
>
> Changes since v1:
>
> - Allowed modifying partial bits of SPI1 strap bitmask instead of strictly
>   allowing only bitmask == BIT[13:12] to go through
> - Rename HW_STRAP_RESET to HW_STRAP_CLEAR and removed (to be obsoleted) macro
>
> Kun Yi (1):
>   pinctrl: aspeed: Enable ASPEED pinctrl driver to modify SPI1 strap
>     bits
>
>  drivers/pinctrl/aspeed/pinctrl-aspeed.c | 22 ++++++++++++++++++++--
>  drivers/pinctrl/aspeed/pinctrl-aspeed.h |  2 +-
>  2 files changed, 21 insertions(+), 3 deletions(-)
>
> --
> 2.8.0.rc3.226.g39d4020
>