[U-Boot] [PATCH v2 1/2] gpio: Add GPIO driver framework for Marvell SoCs

[Ajay Bhargav]

----- "Lei Wen" <adrian.wenl at gmail.com> wrote:

> On Thu, Aug 4, 2011 at 4:51 PM, Albert ARIBAUD
> <albert.u.boot at aribaud.net> wrote:
> > Hi Simon,
> >
> > On 04/08/2011 02:04, Simon Guinot wrote:
> >> Hi Ajay,
> >>
> >> On Wed, Aug 03, 2011 at 10:10:00AM +0530, Ajay Bhargav wrote:
> >>> ----- "Simon Guinot"<simon at sequanux.org>  wrote:
> >>>
> >>>> AFAIK, Orion and Kirkwood SoCs don't provide bitwise set/clear
> for
> >>>> GPIO output/direction registers. Instead, a register must be
> read
> >>>> first to leave other bits unchanged (see __set_direction in
> >>>> kw_gpio.c).
> >>>>
> >>>> Is it possible to handle Armada SoCs GPIOs in a same way ? maybe
> >>>> using
> >>>> the pin registers (gpxx in the Armada struct gpio_reg array) ?
> >>>>
> >>>> If not, this code is not Marvell generic but rather specific for
> >>>> Armada
> >>>> SoCs and then maybe armada_gpio is a better name...
> >>>>
> >>>> Regards,
> >>>>
> >>>> Simon
> >>>
> >>> Hi Simon,
> >>>
> >>> Yes its possible to implement code that way, Armada SoC does have
> GPIO
> >>> registers for set/clear. what about register naming?? I think they
> are
> >>> different for Kirkwood and Orion.
> >>
> >> I think that the register names could be OK. But here is a most
> >> important problem: On Orion/Kirkwood SoCs, a single GPIO output
> register
> >> is available (no set/clear variants as for Armada). I missed that
> point
> >> at my first look. It is quite problematic because only two
> registers are
> >> shared between the different Marvell SoCs: level and direction. In
> fact,
> >> this registers are probably relevant on every machines providing
> GPIOs...
> >>
> >> Maybe that having two common registers is not enough to add
> >> Orion/Kirkwood support to the mvgpio driver ?
> >  >
> >>> One more thing which can be done to make this code generic is to
> have
> >>> some macros which can be defined by individual arch for specific
> registers
> >>> which are going to be in use e.g.
> >>>
> >>> #define GPIO_PIN_LEVEL_REG
> >>> #define GPIO_DIR_REG
> >>> #define GPIO_PIN_SET_REG
> >>> #define GPIO_PIN_CLR_REG
> >>
> >> Yes, but how to handle both a single GPI0 output register and some
> GPIO
> >> {set,clear} output registers (in a nice way) ?
> >
> > Two distinct gipo drivers for the two marvell variants?
> 
> If let I choose, I'd prefer two, since the register set is different.
> 
> Best regards,
> Lei
> 

Hi Simon,

For Armada minimum 3 registers are required and available for armada
1. Direction (read/write)
2. Pin level set (write only)
3. Pin level clear (write only)

@lei
How bout if we check for architecture and use specific code or defines?
i.e.
#ifdef CONFIG_KIRKWOOD
//KW code
#elif CONFIG_ARMADA100
//Armada code
#else
//orion or other?
#endif

Regards,
Ajay Bhargav