On Tue, Feb 26, 2019 at 3:14 AM Fabrice Gasnier <fabrice.gasn...@st.com> wrote:
>
> On 2/25/19 5:53 PM, Rob Herring wrote:
> > On Wed, Jan 30, 2019 at 05:38:53PM +0100, Fabrice Gasnier wrote:
> >> Add documentation for STMicroelectronics STM32 Factory-programmed
> >> read only memory area.
> >>
> >> Signed-off-by: Fabrice Gasnier <fabrice.gasn...@st.com>
> >> ---
> >>  .../devicetree/bindings/nvmem/st,stm32-romem.txt   | 31 
> >> ++++++++++++++++++++++
> >>  1 file changed, 31 insertions(+)
> >>  create mode 100644 
> >> Documentation/devicetree/bindings/nvmem/st,stm32-romem.txt
> >>
> >> diff --git a/Documentation/devicetree/bindings/nvmem/st,stm32-romem.txt 
> >> b/Documentation/devicetree/bindings/nvmem/st,stm32-romem.txt
> >> new file mode 100644
> >> index 0000000..fbff52e
> >> --- /dev/null
> >> +++ b/Documentation/devicetree/bindings/nvmem/st,stm32-romem.txt
> >> @@ -0,0 +1,31 @@
> >> +STMicroelectronics STM32 Factory-programmed data device tree bindings
> >> +
> >> +This represents STM32 Factory-programmed read only non-volatile area: 
> >> locked
> >> +flash, OTP, read-only HW regs... This contains various information such 
> >> as:
> >
> > Several distinct types here. Does s/w need to know the difference
> > rather than just one generic-ish compatible? Access size restrictions
> > maybe? Ability to unlock and program?
>
> Hi Rob,
>
> The reading part is represented here as "st,stm32-romem" compatible, to
> simply handle read only access. I agree this could be a generic-ish.
>
> BUT the specifics are regarding the ability to unlock/lock and program.
> Access size can vary from one part to another (e.g. on stm32f4,
> reference manual sates: OTP area is divided into 16 OTP data blocks of
> 32 bytes. on stm32f7, OTP area is divided into 16 OTP data blocks of 64
> bytes.)
>
> In STM32MP15, both the read & write access through the BSEC are
> specific, represented by dedicated compatible.
>
> Do you wish I update the compatible to something like:
> "st,stm32f4-otp"
> "st,stm32mp15-bsec"
> ?

Yes, I think given the above that makes sense. We can always map
specific bindings to generic drivers, but not the reverse.

Rob

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