linux_dsm_epyc7002/Documentation/devicetree/bindings/mmc/mmc-pwrseq-simple.txt
Ulf Hansson c477ebe21f mmc: dt: pwrseq-simple: Invent power-off-delay-us
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>
2017-05-23 14:17:10 +02:00

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* The simple MMC power sequence provider
The purpose of the simple MMC power sequence provider is to supports a set of
common properties between various SOC designs. It thus enables us to use the
same provider for several SOC designs.
Required properties:
- compatible : contains "mmc-pwrseq-simple".
Optional properties:
- reset-gpios : contains a list of GPIO specifiers. The reset GPIOs are asserted
at initialization and prior we start the power up procedure of the card.
They will be de-asserted right after the power has been provided to the
card.
- clocks : Must contain an entry for the entry in clock-names.
See ../clocks/clock-bindings.txt for details.
- clock-names : Must include the following entry:
"ext_clock" (External clock provided to the card).
- post-power-on-delay-ms : Delay in ms after powering the card and
de-asserting the reset-gpios (if any)
- power-off-delay-us : Delay in us after asserting the reset-gpios (if any)
during power off of the card.
Example:
sdhci0_pwrseq {
compatible = "mmc-pwrseq-simple";
reset-gpios = <&gpio1 12 GPIO_ACTIVE_LOW>;
clocks = <&clk_32768_ck>;
clock-names = "ext_clock";
}