linux-kernel - Re: [[LINUX PATCH v10] 1/4] Devicetree: Add pl353 smc controller devicetree binding information

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Message-ID: <20180624224014.125cf0bc@bbrezillon>
Date:   Sun, 24 Jun 2018 22:40:14 +0200
From:   Boris Brezillon <boris.brezillon@...tlin.com>
To:     Naga Sureshkumar Relli <naga.sureshkumar.relli@...inx.com>
Cc:     <richard@....at>, <dwmw2@...radead.org>,
        <computersforpeace@...il.com>, <marek.vasut@...il.com>,
        <f.fainelli@...il.com>, <mmayer@...adcom.com>, <rogerq@...com>,
        <ladis@...ux-mips.org>, <ada@...rsis.com>,
        <honghui.zhang@...iatek.com>, <miquel.raynal@...tlin.com>,
        nagasureshkumarrelli@...il.com, michals@...inx.com,
        linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [[LINUX PATCH v10] 1/4] Devicetree: Add pl353 smc controller
 devicetree binding information

Hi Naga,

Subject prefix should be "dt-bindings: memory: " not "Devicetree: ".

On Thu, 21 Jun 2018 12:12:28 +0530
Naga Sureshkumar Relli <naga.sureshkumar.relli@...inx.com> wrote:

> Add pl353 static memory controller devicetree binding information.
> 
> Signed-off-by: Naga Sureshkumar Relli <naga.sureshkumar.relli@...inx.com>
> ---
> Changes in v10:
>  - Corrected the typos like "should be" to "Must be" and nand to NAND etc..
>  - Removed padding to describe size-cells and address-cells
>  - Removed timing parameters from DT, and added ->setup_data_interface() hook
>    to the driver to read the SDR timings
>  - Modified label name from "pl353smcc_0: pl353smcc@...0e000" to
>    "smcc: memory-controller@...0e000" as suggested by Miquel
> Changes in v9:
>  - Addressed below comments given by Randy Dunlap and Miquel Raynal
>  - Typos
>  - Added extra documentation that explains the HW ECC limitation with SMC
>    (Comments given to v8: https://lkml.org/lkml/2018/3/22/23)
> Changes in v8:
>  - None
> Changes in v7:
>  - Corrected clocks description
>  - prefixed '#' for address and size cells
> Changes in v6:
>  - None
> Changes in v5:
>  - Removed timing properties
> Changes in v4:
>  - none
> Changes in v3:
>  - none
> Changes in v2:
>  - modified timing binding info as per onfi timing parameters
>  - add suffix nano second as timing unit
>  - modified the clock names as per the IP spec
> ---
>  .../bindings/memory-controllers/pl353-smc.txt      | 41 ++++++++++++++++++++++
>  1 file changed, 41 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/memory-controllers/pl353-smc.txt
> 
> diff --git a/Documentation/devicetree/bindings/memory-controllers/pl353-smc.txt b/Documentation/devicetree/bindings/memory-controllers/pl353-smc.txt
> new file mode 100644
> index 0000000..8b4c65e
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/memory-controllers/pl353-smc.txt
> @@ -0,0 +1,41 @@
> +Device tree bindings for ARM PL353 static memory controller
> +
> +PL353 static memory controller supports two kinds of memory
> +interfaces.i.e NAND and SRAM/NOR interfaces.
> +The actual devices are instantiated from the child nodes of pl353 smc node.
> +
> +Required properties:
> +- compatible		: Must be "arm,pl353-smc-r2p1"
> +- reg			: Controller registers map and length.
> +- clock-names		: List of input clock names - "ref_clk", "aper_clk"
> +			  (See clock bindings for details).
> +- clocks		: Clock phandles (see clock bindings for details).
> +- address-cells		: Must be 1.
> +- size-cells		: Must be 1.
> +
> +Child nodes:
> + For NAND the "arm,pl353-nand-r2p1" and for NOR the "cfi-flash" drivers are
> +supported as child nodes.
> +
> +for NAND partition information please refer the below file
> +Documentation/devicetree/bindings/mtd/partition.txt
> +
> +Example:
> +	smcc: memory-controller@...0e000
> +			compatible = "arm,pl353-smc-r2p1"
> +			clock-names = "memclk", "aclk";
> +			clocks = <&clkc 11>, <&clkc 44>;
> +			reg = <0xe000e000 0x1000>;
> +			#address-cells = <1>;
> +			#size-cells = <1>;
> +			ranges;
> +			nand_0: flash@...00000 {
> +				compatible = "arm,pl353-nand-r2p1"
> +				reg = <0xe1000000 0x1000000>;
> +				(...)
> +			};
> +			nor0: flash@...00000 {
> +				compatible = "cfi-flash";
> +				reg = <0xe2000000 0x2000000>;
> +			};
> +	};

I had a look at the PL353 TRM, and the block diagram looks very similar
to the atmel EBI/SMC one. AHB/AXI memory ranges that are used to
interact with the memories are assigned CS ids, which can then be used
to configure the timings (and other kind of stuff). I think you should
have #address-cells = <2>, the first cell encoding the CS id, and the
second one, the memory offset within the reserved range for this CS id.
See the atmel,ebi binding [1].

Regards,

Boris

[1]https://elixir.bootlin.com/linux/v4.18-rc2/source/Documentation/devicetree/bindings/memory-controllers/atmel,ebi.txt