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Message-ID: <20141006162732.GB3848@lee--X1> Date: Mon, 6 Oct 2014 17:27:32 +0100 From: Lee Jones <lee.jones@...aro.org> To: Pankaj Dubey <pankaj.dubey@...sung.com> Cc: linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, 'linux-samsung-soc' <linux-samsung-soc@...r.kernel.org>, 'Arnd Bergmann' <arnd@...db.de>, b29396@...escale.com, boris.brezillon@...e-electrons.com, 'Tomasz Figa' <tomasz.figa@...il.com>, 'Russell King' <linux@....linux.org.uk>, 'VIKAS SAJJAN C' <vikas.sajjan@...sung.com>, naushad@...sung.com, 'Thomas P Abraham' <thomas.ab@...sung.com>, 'Kukjin Kim' <kgene.kim@...sung.com>, Li.Xiubo@...escale.com, geert+renesas@...der.be, 'Stephen Warren' <swarren@...dia.com>, 'Doug Anderson' <dianders@...omium.org> Subject: Re: [PATCH v7] mfd: syscon: Decouple syscon interface from platform devices On Mon, 06 Oct 2014, Pankaj Dubey wrote: > Hi Lee, > > On Tuesday, September 30, 2014 9:39 PM Doug Anderson wrote, > > Subject: Re: [PATCH v7] mfd: syscon: Decouple syscon interface from platform > > devices > > > > Pankaj, > > > > On Tue, Sep 30, 2014 at 1:35 AM, Pankaj Dubey <pankaj.dubey@...sung.com> > > 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@...db.de> > > > Suggested-by: Tomasz Figa <tomasz.figa@...il.com> > > > Tested-by: Vivek Gautam <gautam.vivek@...sung.com> > > > Tested-by: Javier Martinez Canillas <javier.martinez@...labora.co.uk> > > > Signed-off-by: Pankaj Dubey <pankaj.dubey@...sung.com> > > > Reviewed-by: Arnd Bergmann <arnd@...db.de> > > > Tested-by: Heiko Stuebner <heiko@...ech.de> > > > Reviewed-by: Heiko Stuebner <heiko@...ech.de> > > > --- > > > 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@...omium.org> > > I think now we can take have this patch in. So will you please take this patch. I plan to take this when the merge window has closed. -- Lee Jones Linaro STMicroelectronics Landing Team Lead Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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