Subject: Re: [PATCH 1/3] ARM: dts: Bindings for Altera Quadspi Controller
 Version 2
To: matthew.gerlach@linux.intel.com, vndao@altera.com, dwmw2@infradead.org,
        computersforpeace@gmail.com, boris.brezillon@free-electrons.com,
        richard@nod.at, cyrille.pitchen@wedev4u.fr, robh+dt@kernel.org,
        mark.rutland@arm.com, linux-mtd@lists.infradead.org,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
        gregkh@linuxfoundation.org, davem@davemloft.net, mchehab@kernel.org
References: <1498493619-4633-1-git-send-email-matthew.gerlach@linux.intel.com>
 <1498493619-4633-2-git-send-email-matthew.gerlach@linux.intel.com>
From: Marek Vasut <marek.vasut@gmail.com>
Message-ID: <0bfc282d-2aec-8f36-1528-312f7ded8d9c@gmail.com>
Date: Tue, 27 Jun 2017 11:37:35 +0200
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On 06/26/2017 06:13 PM, matthew.gerlach@linux.intel.com wrote:
> From: Matthew Gerlach <matthew.gerlach@linux.intel.com>
> 
> Device Tree bindings for Version 2 of the Altera Quadspi Controller
> that can be optionally paired with a windowed bridge.
> 
> Signed-off-by: Matthew Gerlach <matthew.gerlach@linux.intel.com>
> ---
>  .../devicetree/bindings/mtd/altera-quadspi-v2.txt  | 37 ++++++++++++++++++++++
>  1 file changed, 37 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/mtd/altera-quadspi-v2.txt
> 
> diff --git a/Documentation/devicetree/bindings/mtd/altera-quadspi-v2.txt b/Documentation/devicetree/bindings/mtd/altera-quadspi-v2.txt
> new file mode 100644
> index 0000000..8ba63d7
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/mtd/altera-quadspi-v2.txt
> @@ -0,0 +1,37 @@
> +* Altera Quad SPI Controller Version 2
> +
> +Required properties:
> +- compatible : Should be "altr,quadspi-v2".
> +- reg : Contains at least two entries, and possibly three entries, each of
> +	which is a tuple consisting of a physical address and length.
> +- reg-names : Should contain the names "avl_csr" and "avl_mem" corresponding
> +	      to the control and status registers and qspi memory, respectively.
> +
> +
> +The Altera Quad SPI Controller Version 2 can be paired with a windowed bridge
> +in order to reduce the footprint of the memory interface.  When a windowed
> +bridge is used, reads and writes of data must be 32 bits wide.
> +
> +Optional properties:
> +- reg-names : Should contain the name "avl_window", if the windowed bridge
> +	      is used.  This name corresponds to the register space that
> +	      controls the window.
> +- window-size : The size of the window which must be an even power of 2.
> +- read-bit-reverse : A boolean indicating the data read from the flash should
> +		     be bit reversed on a byte by byte basis before being
> +		     delivered to the MTD layer.
> +- write-bit-reverse : A boolean indicating the data written to the flash should
> +		      be bit reversed on a byte by byte basis.

Is there ever a usecase where you need to set just one of these props ?
Also, they're altera specific, so altr, prefix should be added.

> +Example:
> +
> +qspi: spi@a0001000 {
> +	compatible = "altr,quadspi-v2";
> +	reg = <0xa0001000 0x40>, <0xb0000000 0x4000000>;
> +	reg-names = "avl_csr", "avl_mem";
> +
> +	flash@0 {
> +		reg = <0>;
> +		label = "FPGA Image";
> +	};
> +};
> 


-- 
Best regards,
Marek Vasut