As can be seen in Arasan's datasheet [1] there are several "corecfg" settings in their SDHCI IP Block that are supposed to be controlled by software. Although the datasheet referenced is a bit vague about how to access corecfg, in Figure 5 you can see that for Arasan's PHY (a separate component than their SDHCI component) they describe the "phyctrl" registers as being "FROM SOC CTL REG", implying that it's up to the licensee of the Arasan IP block to implement these registers. It seems sane to assume that the "corecfg" registers in their SDHCI IP block works in a similar way for all licensees of the IP Block.
Device tree has a model that allows a device to get a reference to random registers located elsewhere in the SoC: sysctl. Let's leverage this model and allow adding a sysctl reference to access the control registers for the Arasan SDHCI PHYs. Having a reference to the control registers doesn't do much for us on its own since the Arasan spec doesn't specify how these corecfg values are laid out in memory. In the SDHCI driver we'll need a map detailing where each corecfg can be found in each implementation. This map can be found using the primary compatible string of the SDHCI device. In that spirit, document that existing rk3399 device trees already have a specific compatible string, though up to now they've always been relying on the driver supporting the generic. Note that since existing devices seem to work fairly well as-is, we'll list the syscon reference as "optional", but it's likely that we'll run into much fewer problems if we can actually set the proper values in the syscon, so it is strongly suggested that any SoCs where we have a map to set the corecfg also include a reference to the syscon. [1]: https://arasan.com/wp-content/media/eMMC-5-1-Total-Solution_Rev-1-3.pdf Signed-off-by: Douglas Anderson <diand...@chromium.org> --- .../devicetree/bindings/mmc/arasan,sdhci.txt | 27 ++++++++++++++++++++-- 1 file changed, 25 insertions(+), 2 deletions(-) diff --git a/Documentation/devicetree/bindings/mmc/arasan,sdhci.txt b/Documentation/devicetree/bindings/mmc/arasan,sdhci.txt index 31b35c3a5e47..b67e623ca1ff 100644 --- a/Documentation/devicetree/bindings/mmc/arasan,sdhci.txt +++ b/Documentation/devicetree/bindings/mmc/arasan,sdhci.txt @@ -9,8 +9,12 @@ Device Tree Bindings for the Arasan SDHCI Controller [4] Documentation/devicetree/bindings/phy/phy-bindings.txt Required Properties: - - compatible: Compatibility string. Must be 'arasan,sdhci-8.9a' or - 'arasan,sdhci-4.9a' or 'arasan,sdhci-5.1' + - compatible: Compatibility string. One of: + - "arasan,sdhci-8.9a" + - "arasan,sdhci-4.9a" + - "arasan,sdhci-5.1" + - "rockchip,rk3399-sdhci-5.1", "arasan,sdhci-5.1": The PHY in rk3399. + For this device it is strongly suggested to include arasan,soc-ctl-syscon. - reg: From mmc bindings: Register location and length. - clocks: From clock bindings: Handles to clock inputs. - clock-names: From clock bindings: Tuple including "clk_xin" and "clk_ahb" @@ -22,6 +26,11 @@ Required Properties for "arasan,sdhci-5.1": - phys: From PHY bindings: Phandle for the Generic PHY for arasan. - phy-names: MUST be "phy_arasan". +Optional Properties: + - arasan,soc-ctl-syscon: A phandle to a syscon device (see ../mfd/syscon.txt) + used to access core corecfg registers. Offsets of registers in this + syscon are determined based on the main compatible string for the device. + Example: sdhci@e0100000 { compatible = "arasan,sdhci-8.9a"; @@ -42,3 +51,17 @@ Example: phys = <&emmc_phy>; phy-names = "phy_arasan"; } ; + + sdhci: sdhci@fe330000 { + compatible = "rockchip,rk3399-sdhci-5.1", "arasan,sdhci-5.1"; + reg = <0x0 0xfe330000 0x0 0x10000>; + interrupts = <GIC_SPI 11 IRQ_TYPE_LEVEL_HIGH>; + clocks = <&cru SCLK_EMMC>, <&cru ACLK_EMMC>; + clock-names = "clk_xin", "clk_ahb"; + arasan,soc-ctl-syscon = <&grf>; + assigned-clocks = <&cru SCLK_EMMC>; + assigned-clock-rates = <200000000>; + phys = <&emmc_phy>; + phy-names = "phy_arasan"; + status = "disabled"; + }; -- 2.8.0.rc3.226.g39d4020
