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