Messages in this thread | | | Date | Thu, 7 Jul 2011 12:37:34 -0600 | From | Grant Likely <> | Subject | Re: [RFC/RFT 1/2] gpio/basic_mmio: add support for enable register |
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On Thu, Jul 07, 2011 at 10:15:31PM +0530, Nori, Sekhar wrote: > Hi Grant, > > On Thu, Jul 07, 2011 at 02:40:54, Grant Likely wrote: > > On Tue, Jul 05, 2011 at 04:15:44PM +1000, Ryan Mallon wrote: > > > On 05/07/11 15:10, Sekhar Nori wrote: > > > >Some GPIO controllers have an enable register > > > >which needs to be written to before a GPIO > > > >can be used. > > > > > > > >Add support for enabling the GPIO. At this > > > >time inverted logic for enabling the GPIO > > > >is not supported. This can be done by adding > > > >a disable register as and when a controller > > > >with this comes along. > > > > > > > >Signed-off-by: Sekhar Nori<nsekhar@ti.com> > > > >--- > > > > > > > <snip> > > > > > > >static int bgpio_setup_io(struct bgpio_chip *bgc, > > > > void __iomem *dat, > > > >@@ -369,6 +401,7 @@ int __devinit bgpio_init(struct bgpio_chip *bgc, > > > > void __iomem *clr, > > > > void __iomem *dirout, > > > > void __iomem *dirin, > > > >+ void __iomem *en, > > > > bool big_endian) > > > > > > The arguments to this function are getting a bit unwieldy :-). Maybe > > > we need to introduce something like: > > > > > > struct bgpio_chip_info { > > > struct device *dev; > > > unsigned long sz; > > > void __iomem *dat; > > > void __iomem *set; > > > void __iomem *clr; > > > void __iomem *dirout; > > > void __iomem *dirin; > > > void __iomem *en; > > > bool big_endian; > > > }; > > > > > > and pass that to bgpio_init instead. It would have the added > > > benefits of making the drivers more readable and that > > > bgpio_chip_info structs in the drivers can probably be marked > > > __initdata also. > > > > Or, what may be better is to make callers directly update the > > bgpio_chip structure. > > I started implementing it this way, but felt that the bgpio_chip > structure also has many internal members (like the spinlock) and > this method will require users to spend quite a bit of time figuring > out which structure members they should initialize and which to leave > for bgpio_init() to do for them. > > There is also the case of direction register which is set from > either dirout or dirin depending upon whether the logic is inverted > or not. The bgpio_chip however needs to deal with a single direction > register offset.
We *absolutely* still need the helper function for the complex settings, but for the non-complex ones, I'd rather just directly access the structure. The kerneldoc documentation of the structure can and should be explicit about what the caller is allowed to do.
g.
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