[PATCH v3] GPIO: Add support for GPIO on CLPS711X-target platform

[linux@arm.linux.org.uk (Russell King - ARM Linux)]

On Sun, Oct 07, 2012 at 01:53:34PM +0400, Alexander Shiyan wrote:
> On Fri, 5 Oct 2012 10:02:04 +0100
> Russell King - ARM Linux <linux@arm.linux.org.uk> wrote:
> 
> > On Mon, Oct 01, 2012 at 07:42:33PM +0400, Alexander Shiyan wrote:
> > > The CLPS711X CPUs provide some GPIOs for use in the system. This
> > > driver provides support for these via gpiolib. Due to platform
> > > limitations, driver does not support interrupts, only inputs and
> > > outputs.
> ...
> > > +++ b/arch/arm/mach-clps711x/include/mach/gpio.h
> > > @@ -0,0 +1,27 @@
> > > +/*
> > > + *  This file contains the CLPS711X GPIO definitions.
> > > + *
> > > + *  Copyright (C) 2012 Alexander Shiyan <shc_work@mail.ru>
> > > + *
> > > + * This program is free software; you can redistribute it and/or modify
> > > + * it under the terms of the GNU General Public License as published by
> > > + * the Free Software Foundation; either version 2 of the License, or
> > > + * (at your option) any later version.
> > > + */
> > > +
> > > +/* Simple helper for convert port & pin to GPIO number */
> > > +#define CLPS711X_GPIO(port, bit)	((port) * 8 + (bit))
> > > +
> > > +/* Temporaty definitions for GPIO-ports */
> > > +/* Will be removed after remove clps_read(write) macros */
> > > +#include <mach/hardware.h>
> > > +#define _PADR	(CLPS711X_VIRT_BASE + PADR)
> > > +#define _PBDR	(CLPS711X_VIRT_BASE + PBDR)
> > > +#define _PCDR	(CLPS711X_VIRT_BASE + PCDR)
> > > +#define _PDDR	(CLPS711X_VIRT_BASE + PDDR)
> > > +#define _PADDR	(CLPS711X_VIRT_BASE + PADDR)
> > > +#define _PBDDR	(CLPS711X_VIRT_BASE + PBDDR)
> > > +#define _PCDDR	(CLPS711X_VIRT_BASE + PCDDR)
> > > +#define _PDDDR	(CLPS711X_VIRT_BASE + PDDDR)
> > > +#define _PEDR	(CLPS711X_VIRT_BASE + PEDR)
> > > +#define _PEDDR	(CLPS711X_VIRT_BASE + PEDDR)
> > 
> > Why can't this file (or the bulk of it) live in drivers/gpio ?
> We should have access for macros in gpio.h from board support files
> and other drivers. From drivers/gpio it not possible.
> If you ask about port definitions, as I say before, it will be
> removed later after rework on platform hardware definitions.

No other drivers should be directly accessing the GPIO registers -
doing so is likely a bug because of the inherent lack of locking,
which will cause race conditions.

All accesses to GPIOs should be done via gpiolib, even from board
support files.