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