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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. Signed-off-by: Heiko Stübner <heiko@sntech.de> Signed-off-by: Doug Anderson <dianders@chromium.org> Reviewed-by: Santosh Shilimkar <santosh.shilimkar@ti.com> [khilman: fix compiler warnings] Signed-off-by: Kevin Hilman <khilman@linaro.org>
21 lines
836 B
Plaintext
21 lines
836 B
Plaintext
menuconfig POWER_AVS
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bool "Adaptive Voltage Scaling class support"
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help
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AVS is a power management technique which finely controls the
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operating voltage of a device in order to optimize (i.e. reduce)
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its power consumption.
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At a given operating point the voltage is adapted depending on
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static factors (chip manufacturing process) and dynamic factors
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(temperature depending performance).
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AVS is also called SmartReflex on OMAP devices.
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Say Y here to enable Adaptive Voltage Scaling class support.
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config ROCKCHIP_IODOMAIN
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tristate "Rockchip IO domain support"
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depends on ARCH_ROCKCHIP && OF
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help
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Say y here to enable support io domains on Rockchip SoCs. It is
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necessary for the io domain setting of the SoC to match the
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voltage supplied by the regulators.
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