[PATCH V4 0/4] mmc: core: Add support for MMC power sequences

[Ulf Hansson]

On 19 January 2015 at 10:13, Ulf Hansson <ulf.hansson at linaro.org> wrote:
> Changes in v4:
>         - Fixed call to kfree() in patch3 and patch4.
>
> Changes in v3:
>         Fixed comments from Mark Rutland:
>         - Document binding in one patch to get the big picture.
>         - Keep code and DT document consistent around how many GPIO resets we
>           support. I decided to go for one GPIO, we can extend that if needed
>           later on.
>         - Change compatible string for simple MMC power sequence and renamed the
>           file for its documentation.
>         - Updated commit messages according to above changes.
>
> Changes in v2:
>         Fixed comments from Russell King:
>         - Renamed pwrseq callbacks and corresponding interface functions.
>         - Move the call to the previous namned ->power_on() callback, to the
>           end of mmc_power_up() to get consistent behavior.
>
>
> This is yet another try to solve the issues of dealing with power sequences for
> the MMC subsystem. The latest attempt, see link below, took a generic approach
> by adding a new top level driver layer. That's was rejected by several reasons.
> http://lwn.net/Articles/602855/
>
> This time the approach is focused to fix the issues for MMC only.
>
> To give a short background, SOCs may specify a specific MMC power sequence. To
> successfully detect an (e)MMC/SD/SDIO card, that power sequence must be followed
> while initializing the card.
>
> To be able to handle these SOC specific power sequences, we add a MMC power
> sequence interface, which helps the mmc core to deal with such.
>
> A MMC power sequence provider then implements a set of callbacks from the above
> mentioned interface. The provider has a corresponding DT compatibility string
> and relies on CONFIG_OF to be set to find it's various resourses, like for
> example a GPIO reset.
>
> The mmc core will from mmc_of_parse() try find a "mmc-pwrseq" DT node and then
> call the corresponding MMC power sequence provider's initialization function.
>
>
> Ulf Hansson (4):
>   mmc: core: Initial support for MMC power sequences
>   mmc: pwrseq: Document DT bindings for the simple MMC power sequence
>   mmc: pwrseq: Initial support for the simple MMC power sequence
>     provider
>   mmc: pwrseq_simple: Add support for a reset GPIO pin
>
>  .../devicetree/bindings/mmc/mmc-pwrseq-simple.txt  |  20 ++++
>  Documentation/devicetree/bindings/mmc/mmc.txt      |  14 +++
>  drivers/mmc/core/Makefile                          |   2 +-
>  drivers/mmc/core/core.c                            |   7 ++
>  drivers/mmc/core/host.c                            |   4 +-
>  drivers/mmc/core/pwrseq.c                          | 109 +++++++++++++++++++++
>  drivers/mmc/core/pwrseq.h                          |  42 ++++++++
>  drivers/mmc/core/pwrseq_simple.c                   |  86 ++++++++++++++++
>  include/linux/mmc/host.h                           |   2 +
>  9 files changed, 284 insertions(+), 2 deletions(-)
>  create mode 100644 Documentation/devicetree/bindings/mmc/mmc-pwrseq-simple.txt
>  create mode 100644 drivers/mmc/core/pwrseq.c
>  create mode 100644 drivers/mmc/core/pwrseq.h
>  create mode 100644 drivers/mmc/core/pwrseq_simple.c
>
> --
> 1.9.1
>

To get some more testing of this code, I have now applied this v4 of
this patchset for my next branch.

Kind regards
Uffe