* Exynos DWC_mobile_storage
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The Exynos provides DWC_mobile_storage interface which supports
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. Embedded Multimedia Cards (EMMC-version 4.5)
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. Secure Digital memory (SD mem-version 2.0)
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. Secure Digital I/O (SDIO-version 3.0)
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. Consumer Electronics Advanced Transport Architecture (CE-ATA-version 1.1)
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The Exynos DWC_mobile_storage provides four channels.
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SOC specific and Board specific properties are channel specific.
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Required SoC Specific Properties:
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- compatible: should be
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- samsung,exynos-dwmmc: for exynos platforms
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- reg: physical base address of the controller and length of memory mapped
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region.
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- interrupts: The interrupt number to the cpu.
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Required Board Specific Properties:
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- #address-cells: should be 1.
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- #size-cells: should be 0.
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- samsung,bus-width: The width of the bus used to interface the devices
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supported by DWC_mobile_storage (SD-MMC/EMMC/SDIO).
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. Typically the bus width is 4 or 8.
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- samsung,timing: The timing values to be written into the
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Drv/sample clock selection register of corresponding channel.
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. It is comprised of 3 values corresponding to the 3 fileds
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'SelClk_sample', 'SelClk_drv' and 'DIVRATIO' of CLKSEL register.
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. SelClk_sample: Select sample clock among 8 shifted clocks.
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. SelClk_drv: Select drv clock among 8 shifted clocks.
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. DIVRATIO: Clock Divide ratio select.
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. The above 3 values are used by the clock phase shifter.
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Example:
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mmc@12200000 {
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samsung,bus-width = <8>;
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samsung,timing = <1 3 3>;
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samsung,removable = <1>;
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}
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In the above example,
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. The bus width is 8
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. Timing is comprised of 3 values as explained below
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1 - SelClk_sample
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3 - SelClk_drv
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3 - DIVRATIO
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. The 'removable' flag indicates whether the the particilar device
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cannot be removed (always present) or it is a removable device.
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1 - Indicates that the device is removable.
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0 - Indicates that the device cannot be removed.
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