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Diffstat (limited to 'Documentation/devicetree/bindings/power/rockchip-io-domain.txt')
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diff --git a/Documentation/devicetree/bindings/power/rockchip-io-domain.txt b/Documentation/devicetree/bindings/power/rockchip-io-domain.txt new file mode 100644 index 000000000000..6fbf6e7ecde6 --- /dev/null +++ b/Documentation/devicetree/bindings/power/rockchip-io-domain.txt @@ -0,0 +1,83 @@ +Rockchip SRAM for IO Voltage Domains: +------------------------------------- + +IO domain voltages on some Rockchip SoCs are variable but need to be +kept in sync between the regulators and the SoC using a special +register. + +A specific example using rk3288: +- If the regulator hooked up to a pin like SDMMC0_VDD is 3.3V then + bit 7 of GRF_IO_VSEL needs to be 0. If the regulator hooked up to + that same pin is 1.8V then bit 7 of GRF_IO_VSEL needs to be 1. + +Said another way, this driver simply handles keeping bits in the SoC's +general register file (GRF) in sync with the actual value of a voltage +hooked up to the pins. + +Note that this driver specifically doesn't include: +- any logic for deciding what voltage we should set regulators to +- any logic for deciding whether regulators (or internal SoC blocks) + should have power or not have power + +If there were some other software that had the smarts of making +decisions about regulators, it would work in conjunction with this +driver. When that other software adjusted a regulator's voltage then +this driver would handle telling the SoC about it. A good example is +vqmmc for SD. In that case the dw_mmc driver simply is told about a +regulator. It changes the regulator between 3.3V and 1.8V at the +right time. This driver notices the change and makes sure that the +SoC is on the same page. + + +Required properties: +- compatible: should be one of: + - "rockchip,rk3188-io-voltage-domain" for rk3188 + - "rockchip,rk3288-io-voltage-domain" for rk3288 +- rockchip,grf: phandle to the syscon managing the "general register files" + + +You specify supplies using the standard regulator bindings by including +a phandle the the relevant regulator. All specified supplies must be able +to report their voltage. The IO Voltage Domain for any non-specified +supplies will be not be touched. + +Possible supplies for rk3188: +- ap0-supply: The supply connected to AP0_VCC. +- ap1-supply: The supply connected to AP1_VCC. +- cif-supply: The supply connected to CIF_VCC. +- flash-supply: The supply connected to FLASH_VCC. +- lcdc0-supply: The supply connected to LCD0_VCC. +- lcdc1-supply: The supply connected to LCD1_VCC. +- vccio0-supply: The supply connected to VCCIO0. +- vccio1-supply: The supply connected to VCCIO1. + Sometimes also labeled VCCIO1 and VCCIO2. + +Possible supplies for rk3288: +- audio-supply: The supply connected to APIO4_VDD. +- bb-supply: The supply connected to APIO5_VDD. +- dvp-supply: The supply connected to DVPIO_VDD. +- flash0-supply: The supply connected to FLASH0_VDD. Typically for eMMC +- flash1-supply: The supply connected to FLASH1_VDD. Also known as SDIO1. +- gpio30-supply: The supply connected to APIO1_VDD. +- gpio1830 The supply connected to APIO2_VDD. +- lcdc-supply: The supply connected to LCDC_VDD. +- sdcard-supply: The supply connected to SDMMC0_VDD. +- wifi-supply: The supply connected to APIO3_VDD. Also known as SDIO0. + + +Example: + + io-domains { + compatible = "rockchip,rk3288-io-voltage-domain"; + rockchip,grf = <&grf>; + + audio-supply = <&vcc18_codec>; + bb-supply = <&vcc33_io>; + dvp-supply = <&vcc_18>; + flash0-supply = <&vcc18_flashio>; + gpio1830-supply = <&vcc33_io>; + gpio30-supply = <&vcc33_pmuio>; + lcdc-supply = <&vcc33_lcd>; + sdcard-supply = <&vccio_sd>; + wifi-supply = <&vcc18_wl>; + }; |