Pankaj, On Tue, Sep 30, 2014 at 1:35 AM, Pankaj Dubey <pankaj.dubey@xxxxxxxxxxx> wrote: > Currently a syscon entity can be only registered directly through a > platform device that binds to a dedicated syscon driver. However in > certain use cases it is desirable to make a device used with another > driver a syscon interface provider. > > For example, certain SoCs (e.g. Exynos) contain system controller > blocks which perform various functions such as power domain control, > CPU power management, low power mode control, but in addition contain > certain IP integration glue, such as various signal masks, > coprocessor power control, etc. In such case, there is a need to have > a dedicated driver for such system controller but also share registers > with other drivers. The latter is where the syscon interface is helpful. > > In case of DT based platforms, this patch decouples syscon object from > syscon platform driver, and allows to create syscon objects first time > when it is required by calling of syscon_regmap_lookup_by APIs and keep > a list of such syscon objects along with syscon provider device_nodes > and regmap handles. > > For non-DT based platforms, this patch keeps syscon platform driver > structure so that syscon can be probed and such non-DT based drivers > can use syscon_regmap_lookup_by_pdev API and access regmap handles. > Once all users of "syscon_regmap_lookup_by_pdev" migrated to DT based, > we can completely remove platform driver of syscon, and keep only helper > functions to get regmap handles. > > Suggested-by: Arnd Bergmann <arnd@xxxxxxxx> > Suggested-by: Tomasz Figa <tomasz.figa@xxxxxxxxx> > Tested-by: Vivek Gautam <gautam.vivek@xxxxxxxxxxx> > Tested-by: Javier Martinez Canillas <javier.martinez@xxxxxxxxxxxxxxx> > Signed-off-by: Pankaj Dubey <pankaj.dubey@xxxxxxxxxxx> > Reviewed-by: Arnd Bergmann <arnd@xxxxxxxx> > Tested-by: Heiko Stuebner <heiko@xxxxxxxxx> > Reviewed-by: Heiko Stuebner <heiko@xxxxxxxxx> > --- > Patch v6 and related discussions can be found here [1]. > > Change since v5: > - Addressed review comments from "Heiko Stuebner". > - Updated commit description. > - Including Arnd's and Heiko's Reviewed-by. > > Change since v5: > - Dropping creation of dummy platform device in of_syscon_register. > - As we are changing syscon to decouple from platform_device, creation of > dummy platform_device does not look good option, and as suggested by Arnd, > I made another attempt so that regmap_mmio_init API should work with NULL > dev pointer itself. Since regmap needs to know about Syscon device node > properties so let's parse device node of syscon in syscon itself for any > such properties and using regmap_config parameter pass all such information > to regmap. Other concern of crashes due to NULL dev pointer in regmap already > addressed in separate patches of regmap. Please see [2] and [3]. > > Changes since v4: > - Addressed Tomasz Figa's comments for v4. > - Added error handing in of_syscon_register function. > - Using devm_regmap_init_mmio instead of regmap_init_mmio. > > Changes since v3: > - Addressed Arnd's comment for v2. > - Updated of_syscon_register for adding dev pointer in regmap_init_mmio. > - For early users created dummy platform device. > > Changes since v2: > - Added back platform device support from syscon, with one change that > syscon will not be probed for DT based platform. > - Added back syscon_regmap_lookup_by_pdevname API so that non-DT base > users of syscon will not be broken. > - Removed unwanted change in syscon.h. > - Modified Signed-off-by list, added Suggested-by of Tomasz Figa and > Arnd Bergmann. > - Added Tested-by of Vivek Gautam for testing on Exynos platform. > > Changes since v1: > - Removed of_syscon_unregister function. > - Modified of_syscon_register function and it will be used by syscon.c > to create syscon objects whenever required. > - Removed platform device support from syscon. > - Removed syscon_regmap_lookup_by_pdevname API support. > - As there are significant changes w.r.t patchset v1, I am taking over > author for this patchset from Tomasz Figa. > > [1]: https://lkml.org/lkml/2014/9/29/99 > [2]: https://lkml.org/lkml/2014/9/18/130 > [3]: https://lkml.org/lkml/2014/9/27/2 > drivers/mfd/syscon.c | 96 ++++++++++++++++++++++++++++++++++++++------------ > 1 file changed, 74 insertions(+), 22 deletions(-) You probably already have enough tags, but just in case. ;) On an rk3288-based system (this patch backported to 3.14): Tested-by: Doug Anderson <dianders@xxxxxxxxxxxx> -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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