Re: [PATCH 5/10] dt: bindings: Add bindings for Marvell Xenon SD Host Controller

[Rob Herring]

On Mon, Oct 31, 2016 at 12:09:54PM +0100, Gregory CLEMENT wrote:
> From: Ziji Hu <huziji@xxxxxxxxxxx>
> 
> Marvell Xenon SDHC can support eMMC/SD/SDIO.
> Add Xenon-specific properties.
> Also add properties for Xenon PHY setting.
> 
> Signed-off-by: Hu Ziji <huziji@xxxxxxxxxxx>
> Signed-off-by: Gregory CLEMENT <gregory.clement@xxxxxxxxxxxxxxxxxx>
> ---
>  Documentation/devicetree/bindings/mmc/marvell,xenon-sdhci.txt | 161 +++++++-
>  MAINTAINERS                                                   |   1 +-
>  2 files changed, 162 insertions(+), 0 deletions(-)
>  create mode 100644 Documentation/devicetree/bindings/mmc/marvell,xenon-sdhci.txt
> 
> diff --git a/Documentation/devicetree/bindings/mmc/marvell,xenon-sdhci.txt b/Documentation/devicetree/bindings/mmc/marvell,xenon-sdhci.txt
> new file mode 100644
> index 000000000000..0d2d139494d3
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/mmc/marvell,xenon-sdhci.txt
> @@ -0,0 +1,161 @@
> +Marvell's Xenon SDHCI Controller device tree bindings
> +This file documents differences between the core mmc properties
> +described by mmc.txt and the properties used by the Xenon implementation.
> +
> +A single Xenon IP can support multiple slots.
> +Each slot acts as an independent SDHC. It owns independent resources, such
> +as register sets clock and PHY.
> +Each slot should have an independent device tree node.
> +
> +Required Properties:
> +- compatible: should be one of the following
> +  - "marvell,armada-3700-sdhci": For controllers on Armada-3700 SOC.
> +  Must provide a second register area and marvell,pad-type.
> +  - "marvell,xenon-sdhci": For controllers on all the SOCs, other than
> +  Armada-3700.

Need SoC specific compatible strings.

> +
> +- clocks:
> +  Array of clocks required for SDHCI.
> +  Requires at least one for Xenon IP core.
> +  Some SOCs require additional clock for AXI bus.
> +
> +- clock-names:
> +  Array of names corresponding to clocks property.
> +  The input clock for Xenon IP core should be named as "core".
> +  The optional AXI clock should be named as "axi".

When is AXI clock optional? This should be required for ?? compatible 
strings.

> +
> +- reg:
> +  * For "marvell,xenon-sdhci", one register area for Xenon IP.
> +
> +  * For "marvell,armada-3700-sdhci", two register areas.
> +    The first one for Xenon IP register. The second one for the Armada 3700 SOC
> +    PHY PAD Voltage Control register.
> +    Please follow the examples with compatible "marvell,armada-3700-sdhci"
> +    in below.
> +    Please also check property marvell,pad-type in below.
> +
> +Optional Properties:
> +- marvell,xenon-slotno:

Multiple slots should be represented as child nodes IMO. I think some 
other bindings already do this.

> +  Indicate the corresponding bit index of current Xenon SDHC slot in
> +  SDHC System Operation Control Register Bit[7:0].
> +  Set/clear the corresponding bit to enable/disable current Xenon SDHC
> +  slot.
> +  If this property is not provided, Xenon IP should contain only one
> +  slot.
> +
> +- marvell,xenon-phy-type:
> +  Xenon support mutilple types of PHYs.
> +  To select eMMC 5.1 PHY, set:
> +  marvell,xenon-phy-type = "emmc 5.1 phy"
> +  eMMC 5.1 PHY is the default choice if this property is not provided.
> +  To select eMMC 5.0 PHY, set:
> +  marvell,xenon-phy-type = "emmc 5.0 phy"
> +  To select SDH PHY, set:
> +  marvell,xenon-phy-type = "sdh phy"
> +  Please note that eMMC PHY is a general PHY for eMMC/SD/SDIO, other than for
> +  eMMC only.

Does this vary per instance on a single SoC? If not, then an SoC 
specific compatible should determine this.

Also, the " phy" part is redundant.

> +
> +- marvell,xenon-phy-znr:
> +  Set PHY ZNR value.
> +  Only available for eMMC PHY 5.1 and eMMC PHY 5.0.
> +  valid range = [0:0x1F].
> +  ZNR is set as 0xF by default if this property is not provided.
> +
> +- marvell,xenon-phy-zpr:
> +  Set PHY ZPR value.
> +  Only available for eMMC PHY 5.1 and eMMC PHY 5.0.
> +  valid range = [0:0x1F].
> +  ZPR is set as 0xF by default if this property is not provided.
> +
> +- marvell,xenon-phy-nr-success-tun:
> +  Set the number of required consecutive successful sampling points used to
> +  identify a valid sampling window, in tuning process.
> +  Valid range = [1:7]. Set as 0x4 by default if this property is not provided.
> +
> +- marvell,xenon-phy-tun-step-divider:
> +  Set the divider for calculating TUN_STEP.
> +  Set as 64 by default if this property is not provided.
> +
> +- marvell,xenon-phy-slow-mode:
> +  Force PHY into slow mode.
> +  Only available when bus frequency lower than 50MHz in SDR mde.
> +  Disabled by default. Please do not enable it unless it is necessary.
> +
> +- marvell,xenon-mask-conflict-err:
> +  Mask Conflict Error alert on some SOC. Disabled by default.
> +
> +- marvell,xenon-tun-count:
> +  Xenon SDHC SOC usually doesn't provide re-tuning counter in
> +  Capabilities Register 3 Bit[11:8].
> +  This property provides the re-tuning counter.
> +  If this property is not set, default re-tuning counter will
> +  be set as 0x9 in driver.
> +
> +- marvell,pad-type:
> +  Type of Armada 3700 SOC PHY PAD Voltiage Controller register.
> +  Only valid when "marvell,armada-3700-sdhci" is selected.
> +  Two types: "sd" and "fixed-1-8v".
> +  If "sd" is slected, SOC PHY PAD is set as 3.3V at the beginning and is
> +  switched to 1.8V when SD in UHS-I.
> +  If "fixed-1-8v" is slected, SOC PHY PAD is fixed 1.8V, such as for eMMC.
> +  Please follow the examples with compatible "marvell,armada-3700-sdhci"
> +  in below.
> +
> +Example:
> +- For eMMC slot:
> +
> +	sdhci@aa0000 {
> +		compatible = "marvell,xenon-sdhci";
> +		reg = <0xaa0000 0x1000>;
> +		interrupts = <GIC_SPI 13 IRQ_TYPE_LEVEL_HIGH>
> +		clocks = <&emmc_clk>, <&axi_clock>;
> +		clock-names = "core", "axi";
> +		bus-width = <8>;
> +		marvell,xenon-emmc;

Not documented. If we need to specify the type of slot/card, then we 
need to come up with a standard property. This was either already done 
or attempted IIRC.

> +		marvell,xenon-slotno = <0>;
> +		marvell,xenon-phy-type = "emmc 5.1 phy";
> +		marvell,xenon-tun-count = <11>;
> +	};
> +
> +- For SD/SDIO slot:
> +
> +	sdhci@ab0000 {
> +		compatible = "marvell,xenon-sdhci";
> +		reg = <0xab0000 0x1000>;
> +		interrupts = <GIC_SPI 55 IRQ_TYPE_LEVEL_HIGH>
> +		vqmmc-supply = <&sd_regulator>;
> +		clocks = <&sdclk>;
> +		clock-names = "core";
> +		bus-width = <4>;
> +		marvell,xenon-tun-count = <9>;
> +	};
> +
> +- For eMMC slot with compatible "marvell,armada-3700-sdhci":
> +
> +	sdhci@aa0000 {
> +		compatible = "marvell,armada-3700-sdhci";
> +		reg = <0xaa0000 0x1000>,
> +		      <phy_addr 0x4>;
> +		interrupts = <GIC_SPI 13 IRQ_TYPE_LEVEL_HIGH>
> +		clocks = <&emmcclk>;
> +		clock-names = "core";
> +		bus-width = <8>;
> +		marvell,xenon-emmc;
> +
> +		marvell,pad-type = "fixed-1-8v";
> +	};
> +
> +- For SD/SDIO slot with compatible "marvell,armada-3700-sdhci":
> +
> +	sdhci@ab0000 {
> +		compatible = "marvell,armada-3700-sdhci";
> +		reg = <0xab0000 0x1000>,
> +		      <phy_addr 0x4>;
> +		interrupts = <GIC_SPI 55 IRQ_TYPE_LEVEL_HIGH>
> +		vqmmc-supply = <&sd_regulator>;
> +		clocks = <&sdclk>;
> +		clock-names = "core";
> +		bus-width = <4>;
> +
> +		marvell,pad-type = "sd";
> +	};
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 1a5c4c30ea24..850a0afb0c8d 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -7608,6 +7608,7 @@ MARVELL XENON MMC/SD/SDIO HOST CONTROLLER DRIVER
>  M:	Ziji Hu <huziji@xxxxxxxxxxx>
>  L:	linux-mmc@xxxxxxxxxxxxxxx
>  S:	Supported
> +F:	Documentation/devicetree/bindings/mmc/marvell,xenon-sdhci.txt
>  
>  MATROX FRAMEBUFFER DRIVER
>  L:	linux-fbdev@xxxxxxxxxxxxxxx
> -- 
> git-series 0.8.10