Re: [PATCH v1 2/2] DT: eFuse: Add binding document for IMG Pistachio eFuse Controller

Re: [PATCH v1 2/2] DT: eFuse: Add binding document for IMG Pistachio eFuse Controller

[Andrew Bresticker]

On Mon, Nov 17, 2014 at 7:19 AM,  <arul.ramasamy-1AXoQHu6uovQT0dZR+AlfA@public.gmane.org> wrote:
> From: Arul Ramasamy <Arul.Ramasamy-1AXoQHu6uovQT0dZR+AlfA@public.gmane.org>
>
> Add binding document for IMG eFuse Controller present on Pistachio SOC.
>
> Signed-off-by: Arul Ramasamy <Arul.Ramasamy-1AXoQHu6uovQT0dZR+AlfA@public.gmane.org>
> Signed-off-by: Jude Abraham <Jude.Abraham-1AXoQHu6uovQT0dZR+AlfA@public.gmane.org>
> Signed-off-by: Naidu Tellapati <Naidu.Tellapati-1AXoQHu6uovQT0dZR+AlfA@public.gmane.org>
> ---
>  .../devicetree/bindings/soc/pistachio/img-efuse.txt    | 18 ++++++++++++++++++
>  1 file changed, 18 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/soc/pistachio/img-efuse.txt
>
> diff --git a/Documentation/devicetree/bindings/soc/pistachio/img-efuse.txt b/Documentation/devicetree/bindings/soc/pistachio/img-efuse.txt
> new file mode 100644
> index 0000000..8643a21
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/soc/pistachio/img-efuse.txt
> @@ -0,0 +1,18 @@
> +* IMG Pistachio eFuse controller
> +
> +Required properties:
> +- compatible: Must be "img,pistachio-efuse".
> +- reg: Must contain the base address and length of the eFuse registers.
> +- clocks: Must contain an entry for each entry in clock-names.
> +  See ../clock/clock-bindings.txt for details.
> +- clock-names: Must include the following entries:
> +  - efuse: External oscillator clock

How is the external oscillator related to efuse?  Also, perhaps it
should be called "osc" since it's not an efuse-specific clock.

> +  - sys: eFuse system interface clock

I don't see a system interface gate clock for efuse in the TRM...
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RE: [PATCH v1 2/2] DT: eFuse: Add binding document for IMG Pistachio eFuse Controller

[Naidu Tellapati]

Hi Andrew,

Many thanks for the review.

>> +++ b/Documentation/devicetree/bindings/soc/pistachio/img-efuse.txt
>> @@ -0,0 +1,18 @@
>> +* IMG Pistachio eFuse controller
>> +
>> +Required properties:
>> +- compatible: Must be "img,pistachio-efuse".
>> +- reg: Must contain the base address and length of the eFuse registers.
>> +- clocks: Must contain an entry for each entry in clock-names.
>> +  See ../clock/clock-bindings.txt for details.
>> +- clock-names: Must include the following entries:
>> +  - efuse: External oscillator clock

> How is the external oscillator related to efuse?  Also, perhaps it
> should be called "osc" since it's not an efuse-specific clock.

This is what I read from the eFuse Controller TRM
(Generic eFuse Controller.Technical Reference Manual.pdf) with respect to this clock.

"Free-running oscillator clock – used to clock the fuse-unload state machine. < 50Mhz"

Please comment.

>> +  - sys: eFuse system interface clock

> I don't see a system interface gate clock for efuse in the TRM ...

This is what I read from the above document about the sys_clk.

"System bus clock, synchronous to the IMGBus1 input. < 400 MHz."

I think this clock enables access to shadow RAM where the eFuses status is stored.

Please comment.

regards,
Naidu.





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Re: [PATCH v1 2/2] DT: eFuse: Add binding document for IMG Pistachio eFuse Controller

[Andrew Bresticker]

Hi Naidu,

On Mon, Nov 17, 2014 at 3:34 PM, Naidu Tellapati
<Naidu.Tellapati-1AXoQHu6uovQT0dZR+AlfA@public.gmane.org> wrote:
> Hi Andrew,
>
> Many thanks for the review.
>
>>> +++ b/Documentation/devicetree/bindings/soc/pistachio/img-efuse.txt
>>> @@ -0,0 +1,18 @@
>>> +* IMG Pistachio eFuse controller
>>> +
>>> +Required properties:
>>> +- compatible: Must be "img,pistachio-efuse".
>>> +- reg: Must contain the base address and length of the eFuse registers.
>>> +- clocks: Must contain an entry for each entry in clock-names.
>>> +  See ../clock/clock-bindings.txt for details.
>>> +- clock-names: Must include the following entries:
>>> +  - efuse: External oscillator clock
>
>> How is the external oscillator related to efuse?  Also, perhaps it
>> should be called "osc" since it's not an efuse-specific clock.
>
> This is what I read from the eFuse Controller TRM
> (Generic eFuse Controller.Technical Reference Manual.pdf) with respect to this clock.
>
> "Free-running oscillator clock – used to clock the fuse-unload state machine. < 50Mhz"
>
> Please comment.

Hmm.. is this the 52Mhz external oscillator on Pistachio?  Or something else?

>>> +  - sys: eFuse system interface clock
>
>> I don't see a system interface gate clock for efuse in the TRM ...
>
> This is what I read from the above document about the sys_clk.
>
> "System bus clock, synchronous to the IMGBus1 input. < 400 MHz."
>
> I think this clock enables access to shadow RAM where the eFuses status is stored.

I don't see a bit in CR_PERIP_CLKEN that corresponds to this... Is
this clock derived directly from SYSCLKOUT or PERIPHSYSCLKOUT (i.e. no
gate specifically for efuse)?
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Re: [PATCH v1 2/2] DT: eFuse: Add binding document for IMG Pistachio eFuse Controller

[James Hartley]

Hi Arul,

On 11/18/14 12:37, Arul Ramasamy wrote:
>
> Hi James Hartley and Ezequiel,
>
> > On Mon, Nov 17, 2014 at 3:34 PM, Naidu Tellapati 
> <Naidu.Tellapati-1AXoQHu6uovQT0dZR+AlfA@public.gmane.org <mailto:Naidu.Tellapati-1AXoQHu6uovQT0dZR+AlfA@public.gmane.org>> wrote:
>
> >> Hi Andrew,
>
> >>
>
> >> Many thanks for the review.
>
> >>
>
> >>> +++ b/Documentation/devicetree/bindings/soc/pistachio/img-efuse.txt
>
> >>> @@ -0,0 +1,18 @@
>
> >>> +* IMG Pistachio eFuse controller
>
> >>> +
>
> >>> +Required properties:
>
> >>> +- compatible: Must be "img,pistachio-efuse".
>
> >>> +- reg: Must contain the base address and length of the eFuse 
> registers.
>
> >>> +- clocks: Must contain an entry for each entry in clock-names.
>
> >>> + See ../clock/clock-bindings.txt for details.
>
> >>> +- clock-names: Must include the following entries:
>
> >>> + - efuse: External oscillator clock
>
> >>
>
> >> How is the external oscillator related to efuse? Also, perhaps it
>
> >> should be called "osc" since it's not an efuse-specific clock.
>
> >>
>
> > This is what I read from the eFuse Controller TRM (Generic eFuse
>
> > Controller.Technical Reference Manual.pdf) with respect to this clock.
>
> >>
>
> > > "Free-running oscillator clock – used to clock the fuse-unload 
> state machine. < 50Mhz"
>
> >>
>
> >> Please comment.
>
> > Hmm.. is this the 52Mhz external oscillator on Pistachio? Or something else?
>
> Could you please help us might be with a help of our Hardware team.
>
The state machine is clocked at XTAL freq (which is 52MHz normally). The 
register interface is driven by the sys_clk (typically 400MHz)

> >>> + - sys: eFuse system interface clock
>
> >>
>
> >> I don't see a system interface gate clock for efuse in the TRM ...
>
> >
>
> >> This is what I read from the above document about the sys_clk.
>
> >
>
> >> "System bus clock, synchronous to the IMGBus1 input. < 400 MHz."
>
> >>
>
> >> I think this clock enables access to shadow RAM where the eFuses 
> status is stored.
>
> > I don't see a bit in CR_PERIP_CLKEN that corresponds to this... Is this clock 
> derived directly from SYSCLKOUT or PERIPHSYSCLKOUT (i.e. no gate 
> specifically for efuse)?
>
> Could you please help us might be with a help of our Hardware team.
>
It is not clock gated, it's fed directly from the PERIPH_SYS_CLK_OUT.

> Thanks and Regards,
>
> R.Arul Raj
>
Thanks,
James
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