On Monday 29 September 2014 14:17:38 Pankaj Dubey 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 where is can be probed and such non-DT based drivers can use > syscon_regmap_lookup_by_pdev API and get access to 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> > --- > Patch v5 and related discussions can be found here [1]. > > 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]. > > > Reviewed-by: Arnd Bergmann <arnd@xxxxxxxx> Looks good to me, thanks a lot! Arnd -- 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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