[PATCH V7 1/2] mtd: spi-nor: Bindings for Cadence Quad SPI Flash Controller driver.

[Vikas MANOCHA]

Ho Marek,



> On Aug 17, 2015, at 9:48 PM, Marek Vasut <marex at denx.de> wrote:
> 
>> On Tuesday, August 18, 2015 at 04:35:55 AM, vikas wrote:
>> Hi Marek,
>> 
>>> On 08/13/2015 08:28 PM, Marek Vasut wrote:
>>> From: Graham Moore <grmoore at opensource.altera.com>
>>> 
>>> Add binding document for the Cadence QSPI controller.
>>> 
>>> Signed-off-by: Graham Moore <grmoore at opensource.altera.com>
>>> Signed-off-by: Marek Vasut <marex at denx.de>
>>> Cc: Alan Tull <atull at opensource.altera.com>
>>> Cc: Brian Norris <computersforpeace at gmail.com>
>>> Cc: David Woodhouse <dwmw2 at infradead.org>
>>> Cc: Dinh Nguyen <dinguyen at opensource.altera.com>
>>> Cc: Graham Moore <grmoore at opensource.altera.com>
>>> Cc: Vikas MANOCHA <vikas.manocha at st.com>
>>> Cc: Yves Vandervennet <yvanderv at opensource.altera.com>
>>> Cc: devicetree at vger.kernel.org
>>> ---
>>> 
>>> .../devicetree/bindings/mtd/cadence_quadspi.txt    | 50
>>> ++++++++++++++++++++++ 1 file changed, 50 insertions(+)
>>> create mode 100644
>>> Documentation/devicetree/bindings/mtd/cadence_quadspi.txt
>>> 
>>> V2: Add cdns prefix to driver-specific bindings.
>>> V3: Use existing property "is-decoded-cs" instead of creating a
>>> 
>>>    duplicate, "ext-decoder". Timing parameters are in nanoseconds,
>>>    not master reference clocks. Remove bus-num completely.
>>> 
>>> V4: Add new properties fifo-width and trigger-address
>>> V7: - Prefix all of the Cadence-specific properties with cdns prefix,
>>> 
>>>      those are in particular "cdns,is-decoded-cs", "cdns,fifo-depth",
>>>      "cdns,fifo-width", "cdns,trigger-address".
>>> 
>>>    - Drop bogus properties which were not used and were incorrect.
>>> 
>>> diff --git a/Documentation/devicetree/bindings/mtd/cadence_quadspi.txt
>>> b/Documentation/devicetree/bindings/mtd/cadence_quadspi.txt new file
>>> mode 100644
>>> index 0000000..ebaf1fd
>>> --- /dev/null
>>> +++ b/Documentation/devicetree/bindings/mtd/cadence_quadspi.txt
>>> @@ -0,0 +1,50 @@
>>> +* Cadence Quad SPI controller
>>> +
>>> +Required properties:
>>> +- compatible : Should be "cdns,qspi-nor".
>>> +- reg : Contains two entries, each of which is a tuple consisting of a
>>> +    physical address and length.  The first entry is the address and
>>> +    length of the controller register set.  The second entry is the
>>> +    address and length of the QSPI Controller data area.
>> 
>> "Controller data area", i think it means mapped NOR Flash address ?
> 
> Probably ; Graham ?
> 
>> If yes, it would be more clear with "Physical base address & size of NOR
>> Flash".
> 
> This is the Direct mode thing, correct ? We don't support this, so I think
> we should drop this bit altogether and keep only one single address in this
> field.

No it's not.

> 
>>> +- interrupts : Unit interrupt specifier for the controller interrupt.
>>> +- clocks : phandle to the Quad SPI clock.
>>> +- cdns,fifo-depth : Size of the data FIFO in words.
>> 
>> It actually is sram-depth, better would be "sram-depth" to avoid confusion.
> 
> Is there any documentation for this piece to which you can point me ?

It's on the controller data sheet , should also be part of socfpga doc, let me know the document you have access to, I will point to the relevant part.

> 
>>> +- cdns,fifo-width: Bus width of the data FIFO in bytes.
>>> +- cdns,trigger-address : 32-bit indirect AHB trigger address.
>> 
>> we might make trigger-address also part of property "reg".
> 
> No, we cannot, it's not part of the controller's base address, is it ?

Ok.

> 
>>> +
>>> +Optional properties:
>>> +- cdns,is-decoded-cs : Flag to indicate whether decoder is used or not.
>> 
>> Not clear about the usage of decoder, if it does not make sense we might
>> remove it from driver.
> 
> Graham ? SoCFPGA uses this decoded-cs thing, so we absolutely can not remove
> it from the driver.
> 
>>> +Optional subnodes:
>> I think flash subnode is mandatory.
> 
> You can have a controller with no SPI NORs on it.

Without spi nor this controller/driver can't be used for anything.

Rgds,
Vikas