Add basic functionality of Renesas SD/MMC driver. It can be used
for both gen3 and gen4 R-car boards, but tested only with H3ULCB,
Salvator XS M3 and Spider boards. This driver working with SDHC
subsystem.
The driver supports regularal reading/writing throught SD/MMC
controller buffer, DMA mode w/o interrupts and timing tuning.
Add gpio5 and sd0 nodes to h3ulcb and salvator xs which are needed
for working with SD cards. The GPIO node is needed for switching
voltage on SD card through gpio regulator driver.
Notes:
* the driver doesn't support SPI mode;
* SCC tuning and DMA mode based on IRQs are enabled by default;
* an address of a data buffer has to be aligned to 128 bytes if it
is not, driver will use non-DMA mode automatically;
* Renesas MMC DMAC doesn't support 64-bit DMA addresses, so for
case when we have 64-bit xref data address we use non-DMA mode;
* SD/MMC controller supports block size between 512 and 1 with
a lot of restrictions, more details you can find in code;
* support of HS400 mode isn't implemented inside driver.
Signed-off-by: Mykola Kvach <mykola_kvach@epam.com>
Mykola Kvach