Messages in this thread | | | Date | Wed, 10 Sep 2014 15:20:19 +0200 | From | Boris BREZILLON <> | Subject | Re: [PATCH 5/5] rtc: at91sam9: add DT bindings documentation |
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On Wed, 10 Sep 2014 14:14:24 +0200 Johan Hovold <johan@kernel.org> wrote:
> On Wed, Sep 03, 2014 at 10:45:34AM +0200, Boris BREZILLON wrote: > > Signed-off-by: Boris BREZILLON <boris.brezillon@free-electrons.com> > > --- > > .../devicetree/bindings/rtc/atmel,at91sam9-rtc.txt | 20 ++++++++++++++++++++ > > 1 file changed, 20 insertions(+) > > create mode 100644 Documentation/devicetree/bindings/rtc/atmel,at91sam9-rtc.txt > > > > diff --git a/Documentation/devicetree/bindings/rtc/atmel,at91sam9-rtc.txt b/Documentation/devicetree/bindings/rtc/atmel,at91sam9-rtc.txt > > new file mode 100644 > > index 0000000..9ca455f > > --- /dev/null > > +++ b/Documentation/devicetree/bindings/rtc/atmel,at91sam9-rtc.txt > > @@ -0,0 +1,20 @@ > > +Atmel AT91SAM9260 Real Time Timer > > + > > +Required properties: > > +- compatible: should be: "atmel,at91sam9260-rtt" > > +- reg: should contain 2 memory regions > > + * the first one encodes the memory region of the RTT controller > > + * the second one encodes the GPBR (General Purpose Backup Resgisters) > > + memory region used to store the current time > > +- interrupts: rtc alarm/event interrupt > > +- clocks: should contain one clock pointing the the slow clk > > + > > +Example: > > + > > +rtc@fffffe00 { > > + compatible = "atmel,at91sam9260-rtt"; > > + reg = <0xfffffd20 0x10 > > + 0xfffffd50 0x4>; > > + interrupts = <1 4 7>; > > + clocks = <&clk32k>; > > +}; > > This does not describe the hardware, but rather a specific software > configuration. > > The RTT is first of all not an RTC (although it can be used as one in a > specific software configuration). And the second register resource above > is not an RTT register, but a general-purpose backup register could be > used for other purposes (which register to use is currently configurable > for legacy booting using CONFIG_RTC_DRV_AT91SAM9_GPBR).
We could use a syscon device (which exposes a regmap) for the GPBR block.
rtc@ffffff20 { compatible = "atmel,at91sam9260-rtt"; reg = <0xfffffd20 0x10>; interrupts = <1 4 7>; clocks = <&clk32k>; atmel,time-reg = <&gpbr 0x0>; };
gpbr: syscon@fffffd50 { compatible = "atmel,at91sam9260-gpbr", "syscon"; reg = <0xfffffd50 0x10>; };
> > This was discussed in the thread where I posted an RFC for this last > year (which you linked to in your original submission thread), but no > conclusion was reached: > > http://www.spinics.net/lists/arm-kernel/msg236292.html > > Johan
-- Boris Brezillon, Free Electrons Embedded Linux and Kernel engineering http://free-electrons.com
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