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During power off, after the GPIO pin has been asserted, some devices like the Wifi chip from TI, Wl18xx, needs a delay before the host continues with clock gating and turning off regulators as to follow a graceful shutdown sequence. Therefore invent an optional power-off-delay-us DT binding for mmc-pwrseq-simple, to allow us to support this constraint. Cc: devicetree@vger.kernel.org Cc: Rob Herring <robh+dt@kernel.org> Cc: linux-mmc@vger.kernel.org Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org> Acked-by: Arnd Bergmann <arnd@arndb.de>
32 lines
1.1 KiB
Plaintext
32 lines
1.1 KiB
Plaintext
* The simple MMC power sequence provider
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The purpose of the simple MMC power sequence provider is to supports a set of
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common properties between various SOC designs. It thus enables us to use the
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same provider for several SOC designs.
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Required properties:
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- compatible : contains "mmc-pwrseq-simple".
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Optional properties:
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- reset-gpios : contains a list of GPIO specifiers. The reset GPIOs are asserted
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at initialization and prior we start the power up procedure of the card.
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They will be de-asserted right after the power has been provided to the
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card.
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- clocks : Must contain an entry for the entry in clock-names.
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See ../clocks/clock-bindings.txt for details.
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- clock-names : Must include the following entry:
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"ext_clock" (External clock provided to the card).
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- post-power-on-delay-ms : Delay in ms after powering the card and
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de-asserting the reset-gpios (if any)
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- power-off-delay-us : Delay in us after asserting the reset-gpios (if any)
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during power off of the card.
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Example:
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sdhci0_pwrseq {
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compatible = "mmc-pwrseq-simple";
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reset-gpios = <&gpio1 12 GPIO_ACTIVE_LOW>;
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clocks = <&clk_32768_ck>;
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clock-names = "ext_clock";
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}
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