| Message ID | 1465859076-4868-7-git-send-email-dianders@chromium.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Am Montag, 13. Juni 2016, 16:04:30 schrieb Douglas Anderson: > Some SD/eMMC PHYs (like the PHY from Arasan that is designed to work > with arasan,sdhci-5.1) need to know the card clock frequency in order to > function properly. Physically in a SoC this clock is exported from the > SDHCI IP block to the PHY IP block and the PHY needs to know the speed. > Let's export the SDHCI card clock using a standard device tree mechanism > so that the PHY can get access to it and query the card clock frequency. > > Signed-off-by: Douglas Anderson <dianders@chromium.org> > Acked-by: Rob Herring <robh@kernel.org> Doug and me talked about how to solve this beforehand, so obviously I'm in favour of doing it like this :-) Reviewed-by: Heiko Stuebner <heiko@sntech.de> -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/Documentation/devicetree/bindings/mmc/arasan,sdhci.txt b/Documentation/devicetree/bindings/mmc/arasan,sdhci.txt index 476604e6ce2a..3404afa9b938 100644 --- a/Documentation/devicetree/bindings/mmc/arasan,sdhci.txt +++ b/Documentation/devicetree/bindings/mmc/arasan,sdhci.txt @@ -30,6 +30,12 @@ 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. + - clock-output-names: If specified, this will be the name of the card clock + which will be exposed by this device. Required if #clock-cells is + specified. + - #clock-cells: If specified this should be the value <0>. With this property + in place we will export a clock representing the Card Clock. This clock + is expected to be consumed by our PHY. You must also specify Example: sdhci@e0100000 { @@ -61,7 +67,9 @@ Example: arasan,soc-ctl-syscon = <&grf>; assigned-clocks = <&cru SCLK_EMMC>; assigned-clock-rates = <200000000>; + clock-output-names = "emmc_cardclock"; phys = <&emmc_phy>; phy-names = "phy_arasan"; + #clock-cells = <0>; status = "disabled"; };