8ed765aac3
The OLPC XO-1.75 laptop includes a SDHCI controller which is 1.8v capable, and it truthfully reports so in its capabilities. This alternate voltage is used for driving new "UHS-I" SD cards at their full speed. However, what the controller doesn't know is that the motherboard physically doesn't have a 1.8v supply available, so attempting to switch to the 1.8v level will result in a situation that cannot be recovered from without physically replugging the SD card. Add a device tree flag that can be used on systems like these, and hook it up to the equivalent SDHCI quirk. Signed-off-by: Daniel Drake <dsd@laptop.org> Reviewed-by: Philip Rakity <prakity@nvidia.com> Signed-off-by: Chris Ball <cjb@laptop.org>
44 lines
1.5 KiB
Text
44 lines
1.5 KiB
Text
These properties are common to multiple MMC host controllers. Any host
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that requires the respective functionality should implement them using
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these definitions.
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Interpreted by the OF core:
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- reg: Registers location and length.
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- interrupts: Interrupts used by the MMC controller.
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Required properties:
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- bus-width: Number of data lines, can be <1>, <4>, or <8>
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Card detection:
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If no property below is supplied, standard SDHCI card detect is used.
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Only one of the properties in this section should be supplied:
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- broken-cd: There is no card detection available; polling must be used.
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- cd-gpios: Specify GPIOs for card detection, see gpio binding
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- non-removable: non-removable slot (like eMMC); assume always present.
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Optional properties:
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- wp-gpios: Specify GPIOs for write protection, see gpio binding
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- cd-inverted: when present, polarity on the cd gpio line is inverted
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- wp-inverted: when present, polarity on the wp gpio line is inverted
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- max-frequency: maximum operating clock frequency
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- no-1-8-v: when present, denotes that 1.8v card voltage is not supported on
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this system, even if the controller claims it is.
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Optional SDIO properties:
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- keep-power-in-suspend: Preserves card power during a suspend/resume cycle
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- enable-sdio-wakeup: Enables wake up of host system on SDIO IRQ assertion
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Example:
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sdhci@ab000000 {
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compatible = "sdhci";
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reg = <0xab000000 0x200>;
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interrupts = <23>;
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bus-width = <4>;
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cd-gpios = <&gpio 69 0>;
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cd-inverted;
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wp-gpios = <&gpio 70 0>;
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max-frequency = <50000000>;
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keep-power-in-suspend;
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enable-sdio-wakeup;
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}
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