Re: [RFC 1/5] ARM: at91: add general purpose backup register (GPBR) support

[Jean-Christophe PLAGNIOL-VILLARD <plagnioj-sclMFOaUSTBWk0Htik3J/w@public.gmane.org>]

On 10:46 Mon 08 Apr     , Johan Hovold wrote:
> On Mon, Apr 08, 2013 at 09:33:29AM +0200, Jean-Christophe PLAGNIOL-VILLARD wrote:
> > On 17:12 Sun 07 Apr     , Johan Hovold wrote:
> > > 
> > > Add General Purpose Backup Register (GPBR) support.
> > > 
> > > Most at91 SoCs have at least four 32-bit General Purpose Backup
> > > Registers (GPBR) powered by backup-power (VDDBU). One such register is
> > > currently used by rtc-at91sam9 driver to store the RTC time base.
> > > 
> > > Make sure the registers are mapped by arch setup code and add generic
> > > accessors for in-kernel use.
> > > 
> > > This is a step in adding device-tree support to the rtc-at91sam9 driver.
> > > 
> > This is a regression
> > 
> > we loose the tracking of what request and use the GPBR
> 
> Implementing the GPBR accessors using a simple global resource was one
> quick way forward to decouple and generalise the GPBR. Of course, this
> could be turned into a more elaborate framework or driver where
> registers are requested and released by other drivers and possibly also
> by user-space.
yes must as we used on SAMA5 to pass the boot source from the firstage of the boot
loader to the other software